Anatomy Notes Fall 2024 PDF

Anatomy Notes, Fall 2024© Dr. Kent Nofsinger, MD Dr. Hannah C Anchordoquy, PhD  Body Organization and Anatomic Terminology Some definitions: Anatomy is defined as: (Greek) “to cut up, to dissect”; it is the science concerned with the physical structure of the organism, i...

Anatomy Notes, Fall 2024© Dr. Kent Nofsinger, MD Dr. Hannah C Anchordoquy, PhD  Body Organization and Anatomic Terminology Some definitions: Anatomy is defined as: (Greek) “to cut up, to dissect”; it is the science concerned with the physical structure of the organism, in this case the human Histology: the study of (normal) tissues Pathology: the study of the disease state and abnormal tissues I. Taxonomic Classification of the human Domain Eukarya Eukaryotic cells o Kingdom Animalia No cell walls, plastids, or photosynthetic pigments ▪ Phylum Chordata Dorsal hollow nerve cord, spinal cord Class Mammalia Mammary glands, hair o Order Primates Well developed brain, prehensile hands ▪ Family Hominidae Large cerebrum, bipedal locomotion Genus Homo Flattened face, prominent chin and nose, with inferiorly positioned nostrils o Species sapiens Largest cerebrum II. Anatomical characteristics 1. Brain weighs about 1350-1400 grams (~3 lbs) Emotion, thought, reasoning, memory, precise, coordinated movement 2. Bipedal locomotion 3. Sigmoid curvature of the spine, anatomy of hips and thighs, arched feet 4. Opposable thumb –true of all primates 5. Well-developed vocal structures, have articulated speech 6. Stereoscopic vision: gives us depth perception III. Levels of organization of the human body A. Cellular Level: basic structural and functional component of life. We have 60-100 trillion cells. 1. Cytosol – jelly-like fluid within the cell membrane, in which the organelles are suspended 2. Organelles – each carries out a specific function within the cell. You should know these and their functions from pre-requisite courses. Ribosomes Endoplasmic reticulum Golgi apparatus Lysosomes  Mitochondria Peroxisomes Cytoskeleton Centrosome and Centrioles Nucleus B. Tissue Level: an aggregation of similar cells that perform a common function. Four principal kinds of tissues: 1. Epithelial: covers body surfaces, lines body cavities, and forms glands and ducts 2. Connective tissues: bind, support, and protect body parts; includes the blood. Has 2 components: a) Matrix: nonliving intercellular material (liquid, semisolid, solid) secreted by tissue cells b) Cells – the resident cells that produce and maintain the matrix 3. Muscle tissue: contracts to produce movement 4. Nervous Tissue: initiates and transmits nerve impulses from one body part to another C. Organ Level: an aggregate of tissue types that perform a specific function. Usually there is a primary tissue and secondary tissue. However, an organ will have all four tissues. D. System Level: a body system consists of various organs that have similar or related functions. Examples – circulatory, respiratory, digestive, nervous, endocrine. The systems of the body are interrelated and make up the organism IV. Anatomical Position Learning anatomy will be very much like learning another language. We need a starting point. A. All anatomical terms are in relationship to what is known as the anatomical position. 1. The body is erect, the feet parallel, the eyes directed forward, the arms to the sides, and the palms directed forward, with the fingers straight down. 2. It is imperative to learn this position, and remember that all anatomical terms come from this position. V. Terms A. Positions 1. Superior: directional reference meaning above 2. Inferior: directional reference meaning below 3. Anterior: pertaining to the front of the body 4. Posterior: pertaining to the back of the body 5. Ventral: towards the chest or belly 6. Dorsal: towards the back 7. Medial: toward the midline of the body 8. Lateral: away from the midline of the body 9. Proximal: toward the trunk of the body 10. Distal: away from the trunk of the body a) Frequently, in the digestive system, proximal means closer to the mouth and distal is closer to the anus b) Sometimes in the circulatory system, proximal means closer to the arterial side, and distal will mean closer to the venous side 11. Ipsilateral: on the same side  12. Contralateral: on the opposite side 13. Rostral (lit.: “towards the beak”) in neuroanatomy, towards the forehead 14. Caudal: in neuroanatomy, away from the forehead, towards the spinal cord B. Movements (typically used to describe the movement at a joint) 1. Flexion: movement that decreases the angle of the parts of the joint 2. Extension: movement that increases the angle of the parts of the joint 3. Hyperextension: extension of the joint past anatomic position- the neck, shoulder, hip 4. Adduction: movement towards the axis or midline of the body 5. Abduction movement away from the midline of the body 6. Supine/supination: placement of a body part so that the anterior surface is superior 7. Pronate/pronation: placement of a body part so that the posterior surface is superior 8. Circumduction: the distal end of the body part describes a circle, but the bone does not rotate C. Special movements (these motions occur at only one or a few of the joints in the body) 1. Inversion: a turning inward, as the ankle 2. Eversion: a turning outward, as the ankle 3. Dorsiflexion, with the ankle, the superior surface of the foot approaches the shin 4. Plantar flexion with the ankle extension of the foot – pointing the toes 5. Retraction: A body part moves posteriorly in a horizontal plane 6. Protraction: A body part moves anteriorly in horizontal plane 7. Elevation: moves a body part superiorly 8. Depression: moves a body part inferiorly 9. Lateral flexion: moves the vertebral column in a lateral direction (to the side) VI. Body Regions There are other ways of describing locations within the human body. Anatomists will talk about regions and quadrants of the abdominopelvic regions as well as the cavities located in the body. In addition, things can be described with respect to various imaginary planes that bisect the body. A. Major Regions of the Body – see text for more complete list and figures 1. Cephalic head 9. Inguinal groin 2. Cervical neck 10. Lumbar lower back 3. Thoracic chest 11. Gluteus buttocks 4. Brachium shoulder to the elbow 12. Femur thigh 5. Antebrachium the forearm 13. Patella kneecap 6. Antecubital the front of the elbow 14. Crus knee to the ankle 7. Carpus wrist 15. Talus the ankle 8. Pubis the anterior pelvis 16. Plantar sole of foot B. Abdominal quadrant system – frequently used clinically; marked by a mid-sagittal and transverse plane through the umbilicus 1. Left upper quadrant 2. Right upper quadrant 3. Left lower quadrant 4. Right lower quadrant C. Abdominal subdivision System  1. Left and Right Hypochondriac regions – a) Left and right upper one-third regions of abdomen 2. Left and Right Lumbar (or Lateral) Regions a) Left and right middle lateral regions of abdomen 3. Left and Right Iliac (or inguinal) regions a) Left and right lower one-third regions of abdomen 4. Epigastric Region a) Upper, central one third of abdomen 5. Umbilical region a) Center of abdomen 6. Hypogastric a) Lower, central one-third of abdomen VII. Body Planes A. Sagittal and Midsagittal Planes: 1. Sagittal plane: a vertical plane that divides the body into left and right portions 2. Midsagittal plane: the plane that passes through the mid-plane of the body, dividing it equally into right and left halves B. Transverse or horizontal 1. Divide the body into superior and inferior portions C. Frontal or coronal 1. A vertical plane that divides the body into anterior and posterior portions VIII. Body Cavities A. Dorsal Body cavity 1. Cranial cavity: contains the brain 2. Vertebral cavity: contains the spinal cord B. Ventral Body Cavity: divided by diaphragm 1. Thoracic cavity: upper or chest cavity a) Pleural two pleural cavities surround the right and left lungs b) Mediastinum: the area between the two lungs c) Pericardial: the cavity that surrounds the heart 2. Abdominopelvic Cavity: lower ventral cavity a) Abdomen: upper contains stomach, small intestine, liver, gall bladder, pancreas, and spleen b) Pelvis: contains the terminal portion of the large intestine, the urinary bladder, certain reproductive organs C. Linings 1. The ventral body cavities are lined with epithelial membranes (please refer to tissues, below) 2. The closed ventral cavities are lined with serous membrane, which comes in 2 layers – a visceral layer which lies on the outer surface of the organ, and a parietal layer, which lines the inner surface of the cavity wall. 3. Each LINING has a different name, depending on which cavity it lines a) Abdominopelvic cavity is lined with peritoneum (so there is a visceral and a parietal peritoneum) b) Pleural cavities are lined with pleura (thus there are visceral and parietal pleura) c) Pericardial cavity is lined with serous pericardium (there is a visceral and a parietal pericardium) IX. Body Membranes A. Mucous membranes (noun – mucus) 1. Produce thick, sticky fluid. Line various cavities and tubes that enter or exit the body: oral, nasal cavities, respiratory, reproductive, digestive systems = OPEN body cavities B. Serous Membranes – line the ventral body cavities = CLOSED body cavities 1. Line the thoracic and abdominopelvic cavities and cover visceral organs, producing a watery lubricant called serous fluid or a transudate. 2. There are two layers: a) Parietal – the outermost layer, surrounds the cavity b) Visceral – the innermost layer, surrounds the organ(s) 3. The subdivisions a) Visceral/parietal pleura; pleural cavity b) Visceral/parietal pericardium; pericardial cavity c) Visceral /parietal peritoneum; peritoneal cavity 4. Greater and lesser omentum are folds of peritoneum that extend from the stomach 5. Mesenteries are double folds of peritoneum that connect the parietal peritoneum with the visceral peritoneum. C. Synovial membranes – produce synovial fluid – fluid within certain joints 1. Composed entirely of connective tissue – the exception to the rule that body cavities are lined by epithelium D. Cutaneous membrane – the skin X. Intercellular junctions: found on lateral sides of epithelial cells A. Zonula occludens or tight junctions: protein molecules in adjacent cell membranes fuse together like a zipper, forming an impermeable barrier, which keeps molecules from passing between cells; e.g., the digestive tract B. Adherens (or adhesive) belt junctions (also called zonula adherens): an anchoring junction which binds to the cytoskeletons of adjacent cells. Reinforces tight junctions. Found around the upper, lateral borders of epithelial tissues where limiting passage between cells is important. C. Desmosomes: Are anchoring junctions, mechanical couplings like rivets scattered along the sides of adjacent cells. More significant than adhesive belt junctions. Found in tissues under mechanical stress, like the heart, skin, uterus. D. Gap junctions: allows chemical to pass between adjacent cells. Gap junctions exist in electrically excitable tissues like the heart and smooth muscle, where passage of ions from one cell to another helps to synchronize the cells together. Vocabulary (be able to define, use, or give examples of) Anatomy Anterior Distal: Inversion Cell Posterior Ipsilateral Eversion Tissue Ventral Contralateral Dorsiflexion Organ Dorsal Flexion Plantar flexion Organ system Medial Extension Supination Superior Lateral: Adduction Pronation Inferior: Proximal Abduction Circumduction Retraction Carpus Iliac Mediastinum Protraction Pubis Epigastric Epi- Elevation Inguinal Umbilical Hypo- Depression Lumbar Hypogastric Gastro- Lateral flexion Gluteus Parietal Osteo- Cephalic Femur Visceral Chondro- Cervical Patella Peritoneum Hyper- Thoracic Crus Pleura Peri- Brachium Talus Pericardium Histology Antebrachium Plantar Perineum Pathology Antecubital Hypochondriac Umbilicus Matrix Study Suggestions 1. Use Flash Cards! Include terms with their definitions, movements, cavities, etc. To help you learn directional terms, put the names of specific body parts – the right eye, left little finger, spleen, etc. on small pieces of paper, and then put the papers into a hat, bucket, the Grand Canyon, or something. Draw 2 pieces of paper out, and describe how they are related to each other: “The right eye is contralateral to the left ear, or the great right toe is medial to the 5th right toe, etc. 2. Be able to describe and define the various the various levels of organization of the human body, and how they relate to one another. 3. Be able to use any of the directional terms listed. 4. Be able to use any of the movement terms listed. 5. Be able to identify major body regions anatomically: cephalic, crus, etc. 6. Know the different planes of the body. 7. Describe the anatomical position. 8. Identify the principal organ systems of the human body. 9. Identify and locate the main body cavities; what is an organ found in each cavity? 10. Name the nine abdominopelvic regions. 11. Identify the quadrants of the abdomen. 12. What are the four membrane types of the body, their characteristics, and location? 13. Which body cavity is associated with serous membranes? Which body cavity has no serous membranes? 14. What are the 2 layers of serous membranes; list 3 areas where serous membranes are located; what are the names of the membranes? 15. What are the 3 types of intercellular junctions and the characteristics and functions of each?  Introduction to Epithelial Tissues XI. General A. Epithelium covers and lines: 1. The skin 2. The coverings of the cardiovascular, digestive, respiratory, urinary, and reproductive system. It covers the walls and organs of the ventral body cavity 3. Names a) Epithelium: skin b) Mesothelium: covers visceral organs and lines body cavities c) Endothelium: lines inner walls of blood and lymphatic vessels B. Glandular: epithelium makes up the majority of the glands of the body 1. Exocrine glands: secretions pass through ducts 2. Endocrine glands: ductless glands that secrete hormones directly into the blood or lymphatic fluid C. Functions: 1. Protect 2. Absorb 3. Filter 4. Excrete/Secrete 5. Sensory reception XII. Characteristics of Epithelium Covering and lining epithelia can be classified by a number of different morphologic characteristics. These include the presence of a basement membrane, the number of cell layers of the tissue, and the shape of the cell. A. Composed of closely packed cells, with little extracellular material (or matrix) B. Polarity: have an apical surface (exposed to external environment) and basal surface (exposed to internal environment – next to a basement membrane) 1. Apical specializations a) Microvilli: fingerlike extensions of the cell that increases the ability to absorb or secrete – kidney tubules, intestinal tract b) Cilia: propel substances along their free surface, like the trachea C. Basement membrane: underlying supportive material 1. Basal lamina: a thin, supportive sheet of noncellular glycoproteins that lies adjacent to the basal surface of the epithelium 2. Reticular lamina: deep to the basal lamina and is a network of collagen protein fibers that are part of the underlying connective tissue D. Innervated – have nerve fibers E. Avascular – have no blood vessels F. Regenerate rapidly XIII. Specific Types of Epithelium A. Classification is based on two factors:  1. Based in part on number of cell layers a) Simple: a single cell layer. (1) Since it is thin, it is concerned with absorption, secretion, and filtration, but not protection. b) Stratified: consists of two or more cell layers stacked on each other (1) Found where protection is important. (2) They regenerate from the basal layer and push apically as they mature c) Pseudostratified: the cells are only a single layer thick, but the cells vary in height and have nuclei located at different levels from the basement membrane, giving the appearance that it is several layers thick. 2. Based in part on cell shape a) Squamous: flattened laterally with sparse cytoplasm. The close fitting, scale-like cells resemble a tiled floor. b) Columnar: are tall and column shaped c) Cuboidal: are boxlike, about as tall as wide B. Simple epithelia – every cell touches the basement membrane 1. Simple squamous epithelia: found where filtration or exchange is a priority, e.g. the filtration capsules of the kidneys, air sacs in the lungs a) Endothelium lines the lymphatic vessels as well as the cardiovascular system. b) Mesothelium is the epithelium found in serous membranes lining the ventral body cavity 2. Simple cuboidal epithelia: are found where secretion and absorption are important: glands, kidney tubules 3. Simple columnar epithelia: are found where absorption and secretion are important: lines the stomach and intestinal tract 4. Pseudostratified columnar: secrete or absorb substances; found along most of the respiratory tract C. Stratified epithelia 1. Stratified squamous epithelia a) Several layers of cells that become progressively flattened as they mature apically b) Forms the epidermis; the outer layer of the skin, where it is keratinized, that is the surface contains keratin, a tough protein. It is also found in the mouth, tongue, pharynx, esophagus, rectum and vagina. 2. Stratified cuboidal a) Uncommon, found in larger ducts of some glands: mammary, sweat, and salivary glands 3. Stratified columnar epithelia: uncommon, found in male urethra 4. Transitional epithelia: cells of its basal layer are cuboidal or columnar, while the apical cells vary in appearance from rounded to flattened depending on the distention of the organ; urinary bladder D. Epithelium - Summary 1. Simple  a) Squamous – lines vascular and lymphatic system (endothelium), air sacs (alveoli), filtration of kidneys b) Cuboidal – kidney tubules, glandular epithlium c) Columnar – stomach, small and large intestine lining d) Pseudostratified – lines the trachea and bronchi 2. Stratified a) Squamous – skin, mouth and esophagus, vagina b) Cuboidal – Uncommon, ducts of mammary, sweat, and salivary glands c) Columnar – uncommon, male urethra d) Transitional – urinary bladder, ureters, urethra XIV. Glandular Epithelia As with membranous epithelia, glandular epithelia can be characterized depending on several morphologic characteristics as well. These include number of cells, branching patterns, shape, and secretion. A. Number of cells 1. Unicellular: single celled glands, like goblet cells found in the epithelial linings of the respiratory and digestive tracts. 2. Multicellular: composed of both secretory and cells that form the walls of the ducts. B. Branching Patterns 1. Simple: ducts do not branch (only 1 generation of ducts) 2. Compound: branching ducts C. Gland shape 1. Tubular: the gland resembles a tube 2. Alveolar or acinar: the gland resembles a flask D. Secretion Types 1. Mucoid: secrete glycoproteins (a larger protein attached to a carbohydrate) called mucin that absorb water to form a slippery mucus 2. Serous: secrete a watery solution that usually contains enzymes, such as the enzyme amylase found in saliva 3. Mixed exocrine glands contain more than one type of gland cell and may produce two different exocrine secretions, one serous and one mucous. The submandibular gland is an example. E. Mechanisms of Release of Secretion 1. Merocrine: secretory vesicles are discharged – goblet cells 2. Apocrine secretion: some of the cytoplasm of the cell becomes the secretory product – milk production by the lactiferous glands. 3. Holocrine secretion: the entire cell becomes packed with secretory products, and the cell dies as the secretion is released – sebaceous hair glands 10  Introduction to Connective Tissues XV. Functions A. Establish a structural framework for the body B. Transport fluids and dissolved materials from one region of the body to another C. Provide protection for delicate organs D. Supporting, surrounding, and interconnecting other tissue types E. Storing energy reserves, especially as lipids F. Defending the body from invasion by microorganisms XVI. Characteristics A. CT is the most abundant tissue in the body, but is never exposed to the environment outside the body B. CT includes fat, bone, cartilage, and blood – tissues quite varied in appearance and function C. Most CT have multiple functions, but no single tissue performs all of these functions D. Basic components: 1. Specialized cells 2. Extracellular protein fibers 3. A fluid known as the ground substance – the matrix that surrounds cells a) Most of the volume of CT is matrix XVII. General Histology of Connective Tissue A. Fibers 1. Collagenous fibers – contain collagen which is flexible but with tremendous strength. It is long, straight and un-branched. Each fiber contains 3 fibrous protein subunits that are wound together like a rope. a) Tendons are almost entirely collagen, and connect muscle to bone b) Ligaments resemble tendons, but connect one bone to another. c) The parallel alignment of collagen fibers allows them to withstand tremendous forces. 2. Reticular fibers – form a delicate latticework or reticulum by branching. Common in lymphatic glands 3. Elastic fibers – contain elastin, which is thinner, wavy, branching, and more elastic than collagen. a) After stretching up to 150% of their original length, they can recoil to their original length B. Intercellular matrices or ground substances 1. Ground substance is usually clear, colorless, and has a consistency similar to maple syrup. 2. It contains a glycosaminoglycan (a protein polysaccharide): hyaluronan. A glycoaminoglycan contains polymers of amino sugars connected to protein. C. Cells 1. General Types a) –blasts: immature or active cells b) –cytes: mature or cells in a quiescent state c) –clasts: cells that remodel or break down connective tissue, such as osteoclasts in bone 2. Specific types 11  a) Fibroblasts: most abundant fixed cell in connective tissue proper. Elongate or stellate (star- shaped) are responsible for production and maintenance of CT fibers. Each fibroblast manufactures and secretes protein subunits that interact to form large extracellular fibers. In addition, secrete hyaluronan. b) Macrophages: are large amoeboid cells that are scattered among the fibers. They engulf and destroy damaged cells or pathogens that enter the tissue. When stimulated, they release chemicals that initiate the inflammatory response, and attract large numbers of wandering cells. c) White blood cells d) Adipocytes: fat cells or adipose cells. A typical cell contains a single enormous lipid droplet, squeezing the nucleus and other organelles to one side. The number of fat cells will vary from region to region and individual to individual e) Mast cells: are small CT cells often clustered around blood vessels. They have secretory histamine granules. Also produce heparin, an anticoagulant that prevents blood from clotting within blood vessels. f) Mesenchymal cells are stem cells that can produce daughter cells that are fibroblasts, macrophages, or other CT cells. g) Tissue specific: osteocytes (bone), chondrocytes (cartilage) D. Classification of Connective Tissue 1. Types a) Connective tissue proper: contains CT cells, extracellular protein fibers, and an abundant ground substance b) Supporting connective tissue: cartilage and bone c) Fluid connective tissue: blood and lymph Connective Tissue Classification Common origin: mesenchyme C.T. Proper Supporting C.T. Fluid C.T. Loose CT Dense CT Cartilage Blood (fewer fibers, (more fibers, Bone (semisolid (solid matrix) Lymph more ground less ground matrix) substance substance Adipose Regular Hyaline Compact Reticular Elastic Elastic Spongy Areolar Irregular Fibrocartilage 12 XVIII. Connective Tissue Proper A. Loose Connective Tissue: much of the space is occupied by ground substance 1. Adipose Tissue: a) Fat is not only an energy source, but supports and protects, as well as insulates. b) Concentrated around the kidneys, in the hypodermis of the skin, surface of the heart, surrounding joints, under side of groin, buttocks, around eyes, and in breasts of sexually mature females. c) For the most part are formed prenatally and during the first year of life. d) Adipocytes are incapable of dividing, but mesenchymal cells can differentiate into additional adipocytes. Adipocytes are not killed by weight reduction. 2. Reticular: a) Characterized by a network of reticular fibers woven through a jelly-like ground substance. b) Contains fibroblasts and macrophages; the latter are phagocytic and ingest foreign materials or deteriorating cells (like RBC’s in the spleen). c) Liver, spleen, lymph nodes, and bone marrow contain reticular CT. 3. Areolar: a) Least specialized of CT b) Separates skin from deeper structures c) Open framework, with ground substance accounting for most of the volume d) Cushions shocks, and can be distorted without damage, and with elastic fibers it is resilient, returning to its normal shape when pressure is relieved. e) Fibers – collagen fibers predominate with some elastic and reticular fibers Mast cells are also present. f) Cells: fibroblasts predominate. g) Intercellular matrices: major feature of the Connective Tissue Proper. Also called interstitial fluid; when it accumulates, as in inflammation or disease, called edema. B. Dense or Collagenous 1. Regular (Dense Regular Connective Tissue): large amounts of densely packed, parallel collagen fibers that run parallel to the direction of force placed on the tissue. Silvery white in appearance, and sometimes called white fibrous CT. a) Tendons – muscles to bones, and transfer force of contraction b) Ligaments – connect bone to bone across articulations (joints) c) Aponeurosis: collagen sheets or ribbons that resemble broad flat tendons 2. Elastic Connective (Yellow Elastic) Tissue: a) Composed primarily of elastic fibers, most fibers run parallel, but there is branching, and have yellow color. b) Found in the walls of large arteries, portions of the trachea and bronchial tubes, and underlies transitional epithelium 3. Irregular (Dense Irregular Connective Tissue): large amounts of densely packed, interwoven collagen fibers that provide tensile strength in any direction. Found in dermis of skin, submucosa of the gastrointestinal tract, and fibrous capsules of joints and organs. XIX. Supporting Connective Tissues A. Cartilage: 13  1. Consists of cartilage cells or chondrocytes in a firm gel that contains complex polysaccharides called chondroitin sulfates associated with proteins. Chondrocytes are the only cells within cartilage, and live in little pockets known as lacunae. Collagen fibers provide the tensile strength. Cartilage produces a chemical that discourages blood vessel formation, and it is avascular. 2. Cartilage grows in 2 ways: a) Appositional – the perichondrium adds additional chondroblasts to the outside edges of the cartilage to widen it. b) Interstitial growth – chondrocytes within the cartilage divide and secrete new matrix – this thickens the cartilage c) Cartilage mostly stops growing in the late teens, however, some slow growth is still possible throughout life, though lack of vascularity means that deposition of new cartilage (such as with injury) is slow. 3. Types of cartilage a) Hyaline: most common. Closely packed but very fine collagen fibers; it is somewhat flexible, so it is the weakest. Examples in the adult: connections between ribs and sternum, supporting cartilage along respiratory tract, covering articular surfaces within synovial joints like the elbow or knee. b) Fibrocartilage: the matrix is reinforced by numerous interwoven, collagen fibers. Found between vertebrae, and in the menisci of the knees. c) Elastic cartilage: similar to hyaline, except that it has abundant elastic fibers that make it very flexible without compromising its strength. This tissue is found in the outer ear, portions of the larynx, and in the auditory canal. B. Bone 1. Most rigid of all CT. 2. Has a rich vascular supply and is active metabolically. 3. About 1/3 of matrix is collagen fibers - flexibility 4. Rest of matrix is formed of calcium salts – mostly calcium phosphate and calcium carbonate – contributes hardness 5. Bone compares favorably to best steel-reinforced concrete on a weight basis Approximate tensile strength of bone and other materials Material Tons/Inch Cast Iron 5-10 Copper 10 BONE 10 Wood 7 Tendon 7 XX. Fluid Connective Tissue A. Blood: 1. Cells or formed elements suspended in a liquid matrix called plasma. 2. Cells include erythrocytes-red blood cells, leukocytes-white blood cells, and platelets 14  a) Leukocytes: white blood cells b) Erythrocytes: red blood cells c) Platelets – cellular fragments that assist in blood clotting B. Lymph 1. Matrix is interstitial fluid – mainly fluid that has left the vascular system and needs to be returned to it 2. Cells are mainly lymphocytes – a type of WBC Vocabulary (be able to define, use, or give examples of) Histology Merocrine Macrophages Cytology Holocrine Mast cells Basement membrane Acinar (alveolar) Tendons Matrix Microvilli Ligaments Epithelium Simple glands Adipose Stratified Compound glands Chondrocytes Simple (tissue) -blast Regular fibers Pseudostratified -cyte Irregular fibers Squamous -clast Loose connective tissue Transitional epithelium Mesenchyme Dense regular and irregular Mesothelium Fibroblast connective tissue Endothelium Fascia Elastic connective tissue Cilia Collagen Hyaline cartilage Apical Reticular Fibrocartilage Serous Elastic fibers Elastic cartilage Mucoid Erythrocytes Apocrine Leukocytes 15 Study Suggestions 1. What are the functions of epithelial tissue? 2. What are the major divisions of epithelial tissue and their functions? 3. What are the morphological characteristics of epithelial tissue? 4. How do we characterize epithelial tissue by cell shape? By cell layer? 5. Be able to histologically identify the major types of epithelium: stratified squamous, pseudostratified, etc., and where each is found. 6. What are the 3 types of epithelial intercellular junctions and the characteristics and functions of each? 7. Be able to classify a gland by the number of cells, branching patterns, and gland shape. 8. What are the 3 secretion types of glands; be able to give examples of where each is found. 9. What are the functions and characteristics of connective tissue (CT)? 10. What are the 3 basic histologic components of CT? 11. What are the 3 basic fibers of CT and their characteristics? 12. Be able to describe general and specific types of CT cells 13. What are mesenchymal cells? 14. What are 2 types of CT Proper? 15. Name and describe 3 types of loose CT. 16. Name and describe 4 types of dense regular CT 17. What are the characteristics of dense irregular CT, and where would it be found? 18. What are 3 types of cartilage? Where is each found? 19. How is cartilage different from bone? 20. What are 2 types of fluid CT. What are the cell types of each? 16  Integumentary System This will be the first system we will discuss this semester, and it will be a discussion of the largest organ in the body as well, the skin. There are numerous part to this system that including skin, hair, nails and skin glands. XXI. General Features of Skin Determines initial impression: consider the time devoted to acne commercials on TV compared to blood pressure medication Mirrors general health of other body systems Largest organ of the body – accounting for ~7% body weight It covers about 21 sq feet in the average adult Averages 1.5 mm thick, depending on location, varying from 6 mm on palms and soles to 0.5mm on tympanic membrane. Coordinates immune response to pathogens and cancers in skin A. Embryology 1. The 2 week embryo: a) Develops the epidermis from the ectoderm b) Develops the dermis from the mesoderm (p.143 of text). B. Layers of Integument 1. Epidermis and dermis 2. Some references include the hypodermis XXII. Functions of the Skin A. Protection 1. Physical barrier to microorganisms, water, excessive UV light 2. Oily secretions – form an acidic film that retards growth of microorganisms, and waterproofs skin B. Temperature Regulation 1. Normal body temperature is maintained by: a) Radiant heat loss from dilated blood vessels b) Evaporation or perspiration – sweat about 100-150 ml/day for every 1-degree increase in body temp. c) Retention of heat from constricted blood vessels: arrectores pilorum, smooth muscle attached to hair follicles contract and cause goose bumps C. Excretion 1. Excretes water, electrolytes, drugs, and urea D. Metabolism 1. Small amounts of UV light are necessary for the synthesis of Vitamin D 3 – which helps to regulate calcium and phosphorus metabolism 2. In more detail: UV radiation from the sun converts 7-dehydrocholesterol to Vit D3. This vitamin travels through the blood to the liver, where a hydroxyl is added to the molecule. From there, it travels to the kidneys for another hydroxyl (=1,25 (OH)2 D = calcitriol which is the active form of 17  the vitamin). From there it travels through the blood to the gut where it increases Ca++ absorption. E. Sensory Reception 1. Cutaneous receptors sensory nerve cells that respond to heat, cold, pressure, touch, vibration 2. Vary in distribution F. Communication 1. Emotions are expressed in skin color 2. Contraction of facial muscles express a variety of emotions 3. Secretions from integumentary glands have odors which may stimulate subconscious responds from others XXIII. Epidermis A. General Features 1. Most superficial protective layer 2. Varies in thickness from 0.007-0.12 mm thick 3. Only the deepest layers are living cells 4. The palms and soles have 5 layers, the rest of the body has 4 layers B. The Five Layers of the Epidermis – deep to superficial 1. Stratum Basale or stratum germinativum a) A single layer of cells along the dermis b) Attached to the basal lamina c) 4 cell types (1) Keratinocytes – specialized keratin-producing cells. Keratin toughens and waterproofs the skin. As the cells are pushed superficially the nuclei degenerate, and the keratin completely dominates the cell. (a) These are the ONLY cells found apical (superficial) to the stratum spinosum (2) Melanocytes – synthesize the pigment melanin, which provides a protective barrier to UV radiation for the basal cells. Melanin is transferred from melanocytes to keratinocytes. In light- skinned people, some of the melanin is digested by lysosomes above the basal layer. (a) Expressions of melanocytic variations (i) Tanning - Gradual exposure to UV results in increased production of melanin within melanocytes (ii) Racial variation - Individual and racial differences in skin color result from different levels of melanocyte activity, not different numbers of melanocytes. (iii) Albinism - Even albinos have normal numbers of melanocytes. Albinism is due to the inability to convert tyrosine to melanin (iv) Freckles – aggregations patches of melanin (v) Vitiligo – localized whitening of skin due to lack of melanocytes (vi) Seborrheic keratosis – “liver spots”: after ~50, brown, plaque-like growths on exposed skin (3) Tactile (Merkel) cells – sensory cells aiding in touch reception (4) Langerhans cells – protective macrophages 2. Stratum Spinosum (“spiny layer”) a) Each time a stem cell in the stratum basale divides, a daughter cell is pushed into the next layer, where it begins to differentiate into a keratinocyte 18  b) Several layers thick c) Keratinocytes are bound together by desmosomes (1) Shrinkage of the cells during fixation, which are bound together by desmosomes, give layer its appearance d) Cell division can continue in this layer – therefore the stratum basale and stratum spinosum are collectively called the stratum germinativum e) Friction at the surface results in additional mitotic activity resulting in a callus 3. Stratum Granulosum a) Cells are now manufacturing large amounts of keratohyalin and keratin b) The cells become flatter and thinner, and cell membranes become thicker c) The nuclei and other organelles disintegrate 4. Stratum Lucidum a) Present only in soles and palms b) Appears glassy, and doesn’t stain well with standard stains 5. Stratum Corneum a) Consists of 15-30 layers of flattened, dead, interlocking cells b) Connections from the stratum spinosum remain intact, adding strength c) Cell are usually shed in large groups or sheets, rather than individually d) Containing large amounts of keratin, it is keratinized or cornified (1) Occurs everywhere except on anterior surface of eyes e) Relatively dry, therefore unsuitable for many microorganisms f) Water resistant, but not waterproof, and we lose about 500 ml (~1 pt) of water a day through the skin g) It takes about 14 days for a cell to move from the stratum basale to the stratum corneum, and about another 14 days before the cells are shed XXIV. The Dermis A. General Features 1. Deep to epidermis, and much thicker 2. Integumentary effectors: muscles or glands that respond to motor impulses from the nervous system 3. Vascular supply – helps regulate body temperature and BP 4. Lines of tension – elastic and collagen fibers are arranged in patterns. a) Decreasing elastic fibers is associated with aging b) Vascular – to support epidermis c) Contains many sweat glands, oil-secreting glands, nerve endings, and hair follicles B. Layers 1. Papillary layer a) Areolar CT b) Superficial layer in contact with the epidermis c) Numerous projections – papillae – extend from the dermis into the epidermis 2. Reticular layer (stratum reticularosum) a) Dense irregular CT, that surrounds blood vessels, hair follicles, nerves, and glands b) Deeper and thicker than the papillary layer 19  c) Can be “torn” during pregnancy or obese individuals (1) Repair leaves a white mark called a linea albicans XXV. Hypodermis or subcutaneous tissue A. Characteristics 1. Not part of the skin, but binds the dermis to underlying organs 2. Composed of areolar CT, adipose, and blood vessels 3. Females typically have an 8% thicker hypodermis than males 4. Stores lipids, insulates, and cushions, regulates temperature 5. Subcutaneous fat is stored a) Men – neck, upper arms, along lower back, over buttocks b) Women – breasts, buttocks, hips, and thighs XXVI. Glands of the integument We spent some time earlier talking about the various types of glands in the body based on cell structure, branching patterns, and secretion patterns. Skin glands are EXOCINE glands, and are formed of epithelial tissue that dips down into the CT of the dermis. There are 2 types: sudoriferous and sebaceous skin glands A. Sweat glands (sudoriferous glands) - distributed over the entire skin surface 1. Eccrine (“secreting”) sweat glands - most numerous, particularly abundant on the palms, soles of feet, and forehead. They are found everywhere in the skin, except the nipples and some parts of the external genitalia a) They are simple, coiled, tubular exocrine glands b) Their secretion method is merocrine c) They secrete sweat (1) 99% H2O, + salts, vit. C, antibodies, traces of metabolic wastes, lactic acid - pH is acidic 2. Apocrine sweat glands - largely confined to the axillary and anogenital areas. a) Apocrine glands larger than eccrine glands b) Their ducts empty into hair follicles c) They generate the same basic secretion as sweat, but also produce fatty substances and proteins. Apocrine sweat is odorless, but with bacterial decomposition, a musky, unpleasant odor may result. d) Secretion method is merocrine, though used to be classified as apocrine (thus their name). Maintenance of “apocrine” name signifies the functional and histologic differences between them and eccrine glands. e) They begin to function at puberty under the influence of hormones. 3. Ceruminous glands are modified apocrine glands in the lining of the external ear canal. a) They secrete sticky, bitter cerumen (= earwax) b) Cerumen is thought to deter insects and block entry of foreign material. c) Water and insect repellant d) Keeps tympanic membrane (ear drum) pliable 4. Mammary glands are specialized sweat glands that secrete milk. B. Sebaceous (“greasy”) glands - simple alveolar glands, found everywhere except palms and soles. 1. Secrete sebum which softens and lubricates the hair and skin 2. Secretion method is holocrine secretion 20  3. Sebum functions: a) slows water loss from the skin b) functions as a bactericide 4. Sebaceous secretion is stimulated by hormones and overactive sebaceous glands may result in the development of acne XXVII. Hair A. Functions – 1. Body hair enables sensing of insects on the skin before they sting us. 2. Scalp hair reduces heat loss, prevents physical trauma, and protects from sunlight. 3. Eyelashes shield the eyes and nose hairs filter particulates and insects from inhaled air. B. Structure - flexible strands of dead, keratinized (with hard keratin, rather than the soft keratin typical of epidermis) cells produced by hair follicles. 1. Shaft projects from the skin = dead cells that make up what we think of as a “hair”. a) Cuticle = outer, single layer of cells with lots of keratin for strength b) Cortex = many layers of flat cells c) Medulla = large cells, loosely packed 2. Root is imbedded in the skin C. Hair texture 1. Coarse vs Fine ➔ dependent on diameter of hair 2. Straight vs Curly ➔ dependent on shape of shaft in x-section: a) Straight b) Wavy c) Kinky D. Follicles - extend from epidermis into the dermis and occasionally into the hypodermis = a pocket in the skin that hair grows out of 1. The bulb is the deep, expanded end. It is wrapped in a knot of sensory nerve endings called a root hair plexus which are stimulated by movement of the hair. 2. Bulb consists of epithelial cells growing/adding new cells to hair: also produce melanin which pigments the hair. 3. An arrector pili muscle attached to the follicle. When contracted, it draws the follicle and hair erect, causing a “bump” to form on the skin. Arrector pili contraction results in “goose bumps” a) Arrector pili muscle is smooth muscle, under involuntary control from the sympathetic nervous system b) Arrector pili stimulation functions in body temperature regulation Tb and “fight or flight” response 4. Follicle activity a) Follicles are typically active for 4 years = active phase. b) A resting phase follows in which the hair remains but does not lengthen. c) Then the hair falls out (LOTS of variation!) (gets pushed out!) when a new active phase begins. d) Male pattern baldness – at adulthood, the follicles response to androgen changes such that the active and resting phases are so short that many hairs never emerge from the follicle before they fall out. e) Treatments either inhibit androgens or increase blood flow to the skin and hair follicles. E. Types of hair: 1. Vellus = body hair of children and women. 2. Terminal hair = hair of scalp, eyebrows, axilla, pubic regions, arms, legs, face, and chest of men. XXVIII. Nails A. Finger and toe nails are scalelike modifications of the epidermis that form a clear protective covering on the dorsal surface of the distal part of a finger or toe. 21  B. They are composed of hard keratin C. Structures: 1. The “nail” corresponds to the superficial keratinized layers of the epidermis. 2. The free edge is the part that needs trimming or filing, that extends over the tip of the finger. 3. The body is the portion of the nail that is visible and attached. 4. The root of the nail is not visible, and is embedded proximally under the skin. 5. The nail bed = the deeper layers of the epidermis extending beneath the nail. 6. Nail matrix = thickened proximal portion of the nail bed responsible for nail growth (visible through the nail as the lighter “crescent moon”. 7. Nail folds = skin folds over the proximal and lateral borders of the nail – also called the eponychium 8. Cuticle = projection of proximal nail fold onto the nail body XXIX. FYI A. Skin cancer: 1. Melanoma a) Arises from melanocytes in skin. b) Ultraviolet radiation causes epidermal cells to mutate and become cancerous. 2. Squamous cell a) Arise from epidermal cells in skin b) Associated with sites of skin damage: including UV light exposure 3. Basal cell a) Accounts for 75% of skin cancers b) Resemble the normal basal layer of the epidermis c) Usually associated with skin damage from UV light Vocabulary Integument Keratinocytes Follicle Epidermis Merkel cells Hair shaft Dermis Langerhans cells Matrix Hypodermis (subcutaneous) Albinism Cuticle Stratum basale Vitiligo Cortex Stratum spinosum Sudoriferous Medulla Stratum granulosum Sebaceous Arrector pili muscle Stratum lucidum Ceruminous Innervate Stratum corneum Apocrine Sebum Cerumen 22 Study Suggestions 1. Name the various parts of the integument. 2. What are the functions of the skin? 3. How does the skin regulate temperature? 4. Why is a small amount of ultraviolet light necessary? 5. What are the layers of the epidermis and where are they located? 6. What are the cell types of the stratum basale? 7. What is a Merkel cell? 8. What are lines of tension? 9. Contrast the vascular supply to the epidermis and the dermis. 10. What are the layers of the dermis? Of what kind of tissue are they composed? 11. What is a linea albicans? 12. Describe the hypodermis. What are its functions? 13. What are the glands of the integument? What does each produce? 23  The Skeletal System The human skeleton has two divisions o the axial skeleton, which includes the skull, bones of the thorax, and the vertebral column, including the sacrum and coccyx o the appendicular skeleton which includes the extremities and their supporting elements: the shoulder and pelvis girdle. o You will be covering the gross anatomy of both of these divisions in the lab. In lecture, we will be covering the histology and general anatomy of bone. XXX. Functions of the Skeletal System At birth the skeleton consists of about 270 bones, which decreases to about 206 bones by adulthood. A. Support 1. Rigid structure to which softer tissues and organs are attached 2. The skeleton can support a weight of up to 5 times the weight of the bones themselves B. Protection 1. The skull protects the brain 2. The vertebral column the spinal cord 3. The rib cage, the heart, lungs, liver, and spleen 4. The pelvic girdle cradles the digestive and reproductive organs C. Hematopoiesis (Hemopoiesis) 1. RBC”S, WBC’s, and platelets are produced from stem cells within the red marrow. An average of 2.5 million RBC’s are produced every second D. Storage 1. The calcium salts of the bone act as a reservoir for valuable minerals like calcium and phosphate. a) 95% of calcium is stored in the bones and teeth b) Calcium is the most abundant mineral in the body; it is necessary for blood clotting, movement of ions across cell membranes, and muscle contraction E. 90% of phosphorus is stored in the skeleton; it is necessary for the activities of the nucleic acids. 1. Magnesium, sodium, fluorine, and heavy metals like strontium are stored in bone tissue 2. Fat stored in the yellow marrow acts as an energy reserve XXXI. Skeletal Cartilage A. Basic structure – consists primarily of water, avascular, no nervous innervation. 1. Surrounded by perichondrium = girdle to resist outward expansion during compression, also carries blood vessels to supply nutrients 2. Composed of cells (chondrocytes) encased in cavities (lacunae) embedded within extracellular matrix (= ground substance + fibers) B. Types and locations 1. Hyaline – most abundant, have only fine collagen fibers a) Articular cartilages b) Costal cartilages c) Respiratory cartilages 24  d) Nasal cartilages 2. Elastic – contains elastin fibers in addition to collagen – better able to withstand repeated bending. Forms external ear and epiglottis 3. Fibrocartilages – highly compressible, has great tensile strength. Perfect intermediate between hyaline and elastic with thick collagen fibers. Found where there’s heavy pressure – menisci of the knee and intervertebral discs C. Growth 1. Appositional – cells in the perichondrium secrete new matrix which is laid down against the external face of the existing cartilage = growth from without. 2. Interstitial - = growth from within. The lacunae bound chondrocytes divide and secrete new matrix, expanding cartilage from within 3. Under some conditions, calcium salts are deposited in the matrix of cartilage. But calcified cartilage is NOT bone – they are always distinct tissues. XXXII. Types of bone A. Long bones 1. Longer than they are wide 2. Function as levers 3. Most of the bones of the upper and lower extremities: a) Humerus b) Radius c) Ulna d) Metacarpal bones e) Femur f) Tibia g) Metatarsal bones h) Phalanges B. Short bones 1. Somewhat cube-shaped 2. Found in wrist and ankle 3. Transfer forces of movement C. Flat bones 1. Broad surface for muscle attachment or protection of underlying organs a) Cranial bones b) Ribs c) Bones of shoulder girdle D. Irregular bones 1. Varied shapes 2. Many surface attachments for muscles or articulation a) Bones of skull, face, vertebrae E. Sesamoid bones 1. Additional bones that develop in tendons in response to stress across a joint a) Patella F. Accessory bones 1. Bones that are supernumerary or not usually present 25  2. Usually short or flat and occur in hands and feet G. Sutural bones 1. Extra bones within the sutures of the skull XXXIII. Gross Anatomy of the “Typical” Long Bone A typical long bone is composed of several different parts that are the same regardless of the bone. These include: A. Layers – 1. Compact bone forms the hard, solid outer layer of the typical long bone. a) Also called “dense bone” b) It is composed of lamellar bone, organized into osteons, discussed below in microscopic anatomy. c) It is present everywhere on the outer surface of all bones, even at their articulating ends. d) In the diaphysis of mature long bones, the collar of bone around the medullary cavity is made of compact bone 2. Spongy bone forms the inner layer of bones. a) Also called cancellous bone b) It is porous, composed of a “honeycomb” of small needle-like projections called trabeculae. It is found predominantly at the epiphyses of long bones, but is also present within membrane bones, such as the flat bones of the skull, where it is called diploe. c) Open spaces within spongy bone are filled with red or yellow marrow (1) Often, the red marrow within spongy bone is the site of hematopoiesis = red blood cell formation. Throughout life the principle sites of hematopoiesis changes, though in the adult major sites include the red marrow within the spongy bone of the ribs, sternum, pelvis, vertebrae, and the proximal ends of the long bones of the lower extremity B. Diaphysis 1. The shaft of a long bone 2. It is a cylinder of compact bone surrounding a central cavity, called the medullary cavity. 3. The shaft normally applies forces from one epiphysis to the other, and is very strong when stressed along that axis. 4. However when stressed tangentially, it is more likely to fracture. C. Epiphysis 1. The ends of a long bone, consists of spongy bone surrounded by compact bone D. Metaphysis or Epiphyseal End plate (also called the epiphyseal line) 1. A relatively narrow zone where the diaphysis joins the epiphysis E. Medullary cavity containing red or yellow marrow 1. Central cavity found in long bones, usually surrounded by spongy bone with an out layer or collar of compact bone. 2. Lined with endosteum 3. Typically filled with yellow marrow – contains large amounts of fat. However, in some bones, and at some developmental points, some medullary cavities may contain red marrow. F. Membranes: 1. Endosteum a) Lining of the medullary cavity and the spaces within spongy bone by a thin layer of connective tissue (1) Covers trabeculae of spongy bone 26  (2) Lines the canals of compact bone (3) Both osteoclasts and osteoblasts are found at the surface where the endosteum and the bone tissue meet. 2. Periosteum a) The outer surface covering of a bone except over articular cartilage. (1) It consists of a layer of dense irregular CT with an inner cellular layer. (2) The inner cellular layer contains osteoblasts and osteoclasts. (3) It is richly innervated and vascular G. Articular cartilage 1. Thin layer of hyaline cartilage that caps long bone epiphyses, and facilitates joint movement. XXXIV. Histology of Compact Bone: the Osteon Compact bone is composed of a histological unit called either the osteon or the Haversian System. You will see both in the literature, and will hear both terms used interchangeably. A. Chemical composition (applies to the trabeculae of spongy bone, too) 1. Organic components a) = cells and osteoid (=organic part of matrix). b) Osteoid = 1/3 of matrix, includes ground substance + collagen fibers, secreted by osteoblasts. c) Collagen gives bone it’s elasticity and flexibility 2. Inorganic components – 65% by mass a) = hydroxyapatites = mineral salts, largely calcium phosphates. b) Gives bone its hardness to resist compression B. The Osteon = the structural unit of compact bone 1. Osteons are elongated cylinders orienteded in parallel to the long axis of the bone. They form tiny, weight-bearing pillars 2. There are multiple structures that make up an osteon: a) Concentric lamellae (1) Concentric circular rings around the central canal of the osteon. (2) The collagen fibers in a single lamella are oriented in a single direction, but the fibers run in opposite directions in alternating lamella. This structure helps compact bone to withstand torsion (twisting). b) Central Canal or Haversian Canal (1) The center of the osteon which contains minute blood vessels and a nerve (2) The canal runs parallel to the length of the long bone, and the normal stresses of force c) Perforating Canal or Volkmann’s Canal (1) Extend roughly perpendicular to the surface of the bone and the osteons (2) Connect the osteon vessels and nerves to larger trunks d) Lacunae (1) Small pockets or cavities occupied by osteocytes, regularly arranged between the lamellae e) Canaliculi (1) Little channels which radiate through the matrix of the lacuna (2) Contain the cytoplasmic processes of osteocytes, and allow diffusion of nutrients and waste through ground substance, or intercellular gap junctions C. Interstitial lamellae 27  1. Fill in the spaces between the osteons in compact bone 2. Also have lacunae and canaliculi 3. May have been produced during the growth of the bone, or represent remnants of osteons D. Circumferential lamellae – just deep to the periosteum 1. These lamellae are not incorporated into osteons, but rather extend around the entire circumference of the shaft of the bone 2. Resist twisting of a long bone as a whole XXXV. Types of Cells found in bone A. Osteogenic or osteoprogenitor cells 1. Found in bone along the periosteum and endosteum; in response to a fracture or trauma, they give rise to osteoblasts and osteoclasts B. Osteoblasts 1. Are cuboidal shaped cells that form bone. They secrete the organic materials of the bone matrix that become mineralized by an unknown mechanism. C. Osteocytes 1. Mature bone cells that regulate the protein and mineral content of the surrounding matrix. Can release or deposit calcium to the surrounding matrix. They occupy lacunae D. Osteoclasts 1. Are giant cells with 50 or more nuclei. They secrete acid, which dissolve the bony matrix in a process called osteolysis. 2. Osteoclasts are always removing matrix and releasing minerals, and osteoblasts are always producing matrix that quickly binds minerals XXXVI. Bone development A. Embryonic and fetal development of bone – 1. First 8 weeks of development; skeleton is constructed entirely from fibrous membranes and hyaline cartilage 2. Most long bones begin ossifying by 8 weeks post conception and have obvious primary ossification centers by 12 weeks 3. At birth, most long bones are well ossified except for their epiphysis 4. After birth, secondary ossification centers develop in a predictable sequence 5. Epiphyseal plates persist and provide for long bone growth during childhood and the sex hormone-mediated growth spurt at adolescence. B. Formation of the bony skeleton 1. Intramembranous ossification = when a bone develops from a fibrous membrane = formation of membrane bone a) Most bone of the skull and the clavicles (which are all flat bones) b) Ossification center appears in the fibrous connective tissue membrane – embryonic cells cluster and differentiate into osteoblasts (= bone forming cells) which start secreting osteoid. When they get trapped within the matrix they secrete, they become osteocytes. The osteocytes form woven bone (trabeculae). Periosteum forms from embryonic cells accumulating on the external faces of the trabeculae. A collar of compact bone forms and red marrow appears – trabeculae deep to the periosteum thicken, forming the collar, which is later replaced with mature lamellar bone, while the vascular tissue within the spongy bone becomes red marrow 28  2. Endochondral ossification = bone formation by replacement of hyaline cartilage = formation of cartilage or endochondral bone a) Applies to essentially all bones from the base of the skull down. b) Uses hyaline cartilage models for bone construction c) Center of hyaline cartilage shaft forms primary ossification center where bone formation begins. (1) Perichondrium becomes vascularized, turns into periosteum, which stimulates underlying embryonic cells to differentiate into osteoblasts. These cells secrete osteoid against the hyaline cartilage diaphysis, encasing it in a bone collar. The cartilage in the center of the diaphysis calcifies, killing the chondrocytes. Their matrix dies and deteriorates, which opens up an internal cavity. Elsewhere, the cartilage keeps dividing and growing (2) These cavities are invaded by the periosteal bud (a nutrient artery and vein, nerves, red marrow elements, osteoblasts and osteoclasts). The osteoclasts erode the calcified cartilage and osteoblasts secrete osteoid around the remnants of the hyaline cartilage, forming bone- covered cartilage trabeculae (3) As primary ossification center enlarges proximally and distally, osteoclasts break down the new spongy bone and open up a medullary cavity. The epiphyses are still rapidly dividing cartilage – forms larger hyaline cartilage model. Cartilage continues to divide, calcifies, is eroded, then replaced by bony spicules on the epiphyseal surfaces facing the medullary cavity, so that ossification “chases” cartilage formation along the length of the shaft (4) At birth we have long bones with a bony diaphysis surrounding remnants of spongy bone, a widening medullary cavity, and two cartilagenous epiphyses. d) Then, shortly after birth, secondary ossification centers appear in one or both epiphyses, and the epiphyses gain bony tissue. (1) Just like primary ossification, except that it happens in the epiphyses, and the spongy bone in the interior is retained so no medullary cavity forms. (2) When secondary ossification is complete, hyaline cartilage remains only on the articular surfaces and at the epiphyseal plates for growth. C. Postnatal growth – during infancy and youth, long bones lengthen entirely by interstitial growth of the epiphyseal plates, and all bones grow in width by appositional growth 1. Growth in length of long bones (interstitial) – cartilage at epiphyseal plate facing the shaft exhibits rapid growth – pushes epiphyses away from diaphysis. a) Older cells (closer to shaft) hypertrophy, lacunae erode and enlarge, surrounding cartilage matrix calcifies, and the cells die, leaving long spicules of calcified cartilage at the epiphysis- diaphysis junction. b) These are invaded, osteoclasts erode the spicules, then they’re covered with bone matrix by osteoblasts, forming spongy bone. The tips of the trabeculae are eventually consumed by osteoclasts, allowing medullary cavity to lengthen as well. c) At the end of adolescence, the activity of the chondroblasts in the epiphyseal plates wanes, the plates become thinner and thinner, until they are entirely replaced by bone. 2. Growth in width (appositional) – Oseoblasts beneath the periosteum secrete bone matrix on the external bone surface as osteoclasts on the endosteal surface of the diaphysis remove bone. There is normally slightly less breakdown than building, producing a thicker, stronger bone… (these rates change in adulthood, where bone breakdown outpaces growth). D. Development of bones tissue after adolescence 1. By 25 years, nearly all bones are completely ossified and skeletal growth ceases 29  2. In children and adolescents, bone formation outpaces bone resorption, in young adults these processes balance, in old age, resorption predominates. 3. Despite environmental factors that influence bone density, genetics still plays the major role in determining one’s bone density. E. Population dynamics of bone: 1. skeletal mass is generally greater in males than in females, and in blacks than in whites 2. With age, the rate of bone loss is faster in whites than blacks, and in females than in males F. Effect of aging on bone tissue 1. Beginning in the 40’s bone mass decreases with age – (exception is bones of the skull) 2. Osteoporosis – bone resorption outpaces bone deposition a) Bone composition remains normal but bone mass is reduced b) Bones become lighter and more porous c) Affects the entire skeleton, but spongy bone of the spine is the most vulnerable – compression fractures of the vertebrae are common, also the femur at the neck (broken hip) d) Most common in postmenopausal women e) Both estrogen and testosterone help to maintain the health and normal density of skeleton (1) by restraining osteoclast activity (breaks down bone) (2) and promoting bone deposition f) Post menopause, estrogen deficiency means these positive effects are absent g) Other contributing factors: (1) insufficient exercise to stress bones, (2) diet poor in calcium and protein, (3) abnormal vitamin D receptors, (4) smoking (which reduces estrogen levels) h) Treated with calcium and Vit D supplements, increased weight-bearing exercise, and HRT (for those not on HRT there is Fosamax which suppresses osteoclast activity, or Evista which is an estrogen mimic without targeting reproductive organs) i) Prevention is important – activities and lifestyles that promote bone deposition while it’s still possible: by 35 to 40 for long bones, 25 to 30 for spongy bones XXXVII. Bone homeostasis A. Bone remodeling = bone deposition and resporption occurring at the periosteal and endosteal surfaces – occurs continuously in healthy adults. Ex: the distal femur is fully replaced every five to six months!! 1. Deposition: where bone is injured or additional strength is required (requires adequate dietary intake of proteins, vit. C, D, A + minerals like Ca++, phosphorus, magnesium, etc… a) New bone is laid down by osteocytes – they secrete unmineralized matrix which “matures”, and is then infiltrated with mineral salts to form bone 2. Resorption: Performed by osteoclasts which dissolve pits into the bone by secreting: a) Lysosomal enzymes which digest the organic matrix b) Acids that convert the Ca++ salts into soluble forms that pass easily into solution c) These are absorbed into the osteoclasts (endocytosis) and released to the interstitial fluid and thus the blood. 3. Control: 30  a) Hormone mechanism = negative feedback loop driven by Ca++ levels in the blood. Hormone regulators are calcitonin from the thyroid gland and parathyroid hormone from the parathyroid glands. b) Response to mechanical stress = bones respond to mechanical stress by laying down additional material where it’s needed for structural reinforcement. Mechanism is unknown – maybe electrical current generated when bone is deformed? XXXVIII. Diseases of bone A. Developmental 1. Spina bifida: congenital defect where the vertebral laminae fail to fuse 2. Cleft palate/cleft lip: vary in severity B. Nutritional/hormonal 1. Rickets: Vitamin D deficiency in children 2. Osteomalacia: demineralization due to Vitamin D deficiency in adults 3. Gigantism: hypersecretion of growth hormone prior to ossification of growth plates 4. Acromegaly: hypersecretion of growth hormone after ossification of growth plates, resulting in hypertrophy of the bones of the face, hands, and feet 5. Dwarfism: growth hormone deficiency C. Neoplasms (neo=new and plasm=substance, tissue; hence a tumor) 1. Osteoma – benign tumor of bone, often the skull 2. Osteoid osteomas – painful benign tumors of long bones 3. Osteogenic sarcoma – malignant (cancerous) tumor XXXIX. Bone Trauma and injury A. Fractures 1. Can be pathologic – a disease that weakens the bone 2. Traumatic B. Traumatic Fracture Types 1. Simple or closed: The fractured bone doesn’t break through the skin. 2. Compound or open: the fractured bone is exposed to the surface of the skin. 3. Partial or fissured: the bone is incompletely broken. 4. Complete: The fracture has separated the bone into two pieces. 5. Comminuted: the bone is splintered into several fragments. 6. Spiral: the fracture line is twisted as it is broken. 7. Greenstick: An incomplete break in which one side is broken and the other is bowed. 8. Impacted: One end of a broken bone is driven into another 9. Depressed: the broken portion of the bone is driven inward. 10. Displaced: A fracture in which the bone fragments are not in anatomical alignment 11. Nondisplaced: A fracture in which the bone fragments remain in anatomical alignment. Vocabulary Axial Hematopoiesis Metatarsal Appendicular (hemopoiesis) Phalanges Metacarpal Sesamoid 31  Diaphysis Interstitial lamellae Osteogenic cells Epiphysis Central canal (Haversian Osteoblasts Metaphysis canal) Osteocytes Medullary cavity Perforating canal Osteoclasts Endosteum (Volkmann’s canal Intramembranous Periosteum Lacunae ossification Articular Canalicula (pl: canaliculi) Endochondral Concentric lamellae Osteon ossification Study Suggestions 1. What are the 2 divisions of the skeleton? What bones are in each? 2. What are the functions of the skeletal system? 3. What materials are stored in the bone? 4. What are the types of bone? If given an example, can you identify a bone’s type? (Ex: the humerus is a long bone.) 5. What are the parts or divisions of a long bone? Where are they located, and what does each do? 6. Can you identify the various portions of an osteon, and the function of each? 7. What are the various types of bone cells, and what is the role of each? 8. What are the 2 types of embryonic ossification? What steps are involved in each? 32  Axial Skeleton Much of the gross anatomy of the bone will be covered in the lab. Unfortunately, time constraints limit the amount of time that we can give to this topic in lecture. XL. The Skull A. General Features 1. Cranial bones: enclose the brain and sensory organs - 8 of them 2. Facial bones: frame the face and support the teeth – 14 3. Cavities: a) Cranial – largest with capacity of 1300-1350 cc. Formed by cranial and facial bones b) Nasal – divided into 2 nasal fossae by a nasal septum c) Paranasal sinuses – 4 sets: frontal, ethmoidal, sphenoidal, maxillary sinuses d) Middle and inner ear cavities e) Orbits f) Oral or buccal cavity – only partially lined by bone 4. Fontanels: fetal and infant cranial bones not fused, but covered with connective tissue a) Allow for molding and growing b) Ossification complete by 20-24 months c) Anterior: most prominent, diamond shaped d) Posterior: smaller, diamond shaped e) Anterolateral: small and irregular, paired f) Posterolateral: small and irregular, paired 5. Sutures – a fibrous joint found between bones of the skull - covered in lab a) Sagittal b) Coronal c) Lambdoid d) Squamous 6. Foramina: an opening in an anatomical structure; usually a bone -covered in lab a) Refer to Table 7.1 for list of Major Foramina 7. Associated bones - not part of skull but associated with it: a) Hyoid – unique doesn’t directly attach to any other bone b) Auditory Ossicles: malleus, incus, and stapes XLI. Cranial bones A. Frontal – fuse by age 6 1. Contains frontal sinuses 2. Supraorbital margin 3. Supraorbital foramen: supraorbital n and a B. Parietal C. Temporal 1. Squamous – flat plate at sides of skull a) Includes zygomatic process, and mandibular fossa 2. Tympanic part – a) External acoustic meatus (passageway or canal) 33  b) Styloid process (supports hyoid and some tongue muscles 3. Mastoid – a) Stylomastoid foramen allows passage of the facial nerve 4. Petrous part = rocky – the floor of cranium a) Carotid canal – anterior b) Jugular foramen – more posterior D. Occipital bone 1. Foramen magnum – spinal cord 2. Occipital condyles on each side which articulate with C1 (the atlas) 3. Hypoglossal canal – anterolateral edge of condyles 4. External occipital protuberance 5. Superior nuchal line: a bony ridge extending laterally E. Sphenoid bone 1. Lesser wing a) Optic canal – through lesser wing 2. Greater wing a) Superior orbital fissure between lesser and greater wings 3. Body a) Foramen rotundum – opening just posterior to superior orbital fissure; maxillary n passes through b) Foramen lacerum – between sphenoid and petrous part of the temporal bone; no major nerves or vessels c) Sella turcica – houses pituitary gland 4. Lateral ptergoid plate a) Foramen ovale allows passage of the mandibular nerve b) Foramen spinosum – small opening at posterior angle of sphenoid through which middle meningeal vessels pass F. Ethmoid bone 1. Perpendicular plate inferior projection that divides forms superior nasal septum 2. Cribriform plate – numerous foramina for passage of olfactory nerves 3. Crista galli – attachment for meninges 4. Superior and middle concha – turbinates 34 Bone Foramina* Structures Transmitted Frontal bone Supraorbital foramen Supraorbital nerve, artery, and vein; ophthalmic nerve Parietal bone Parietal foramen Emissary vein of superior sagittal sinus Temporal bone Carotid canal Internal carotid artery External acoustic Sound waves to eardrum meatus Internal acoustic Vestibulocochlear and facial nerves; internal meatus auditory vessels Stylomastoid foramen Facial nerve Mastoid foramen Meningeal artery; vein from sigmoid sinus Temporal-occipital region Jugular foramen Internal jugular vein; glossopharyngeal, vagus, and accessory nerves Temporal-occipital- Foramen lacerum No major nerves or vessels; closed by sphenoid region cartilage Occipital bone Foramen magnum Spinal cord; accessory nerve; vertebral arteries Hypoglossal canal Hypoglossal nerve to muscles of tongue Condylar canal Vein from transverse sinus Sphenoid bone Foramen ovale Mandibular division of trigeminal nerve; accessory meningeal artery Foramen rotundum Maxillary division of trigeminal nerve Foramen spinosum Middle meningeal artery; spinosal nerve; part of trigeminal nerve Optic foramen Optic nerve; ophthalmic artery Superior orbital fissure Oculomotor, trochlear, and abducens nerves; ophthalmic division of trigeminal nerve; ophthalmic veins Ethmoid bone Olfactory foramina Olfactory nerves Maxilla Infraorbital foramen Infraorbital nerve and vessels Incisive foramen Nasopalatine nerves Lacrimal bone Inferior orbital fissure Infraorbital nerve; zygomatic nerve; infraorbital vessels Palatine bone Lacrimal foramen Tear duct leading to nasal cavity Zygomatic bone Greater palatine Palatine nerves foramen Zygomaticofacial Zygomaticofacial nerve foramen Mandible Zygomaticotemporal Zygomaticotemporal nerve foramen Mental foramen Mental nerve and vessels Mandibular foramen Inferior alveolar nerves and vessels to the lower teeth 35 *When two or more bones are listed together (for example, temporal-occipital), it indicates that the foramen passes between them. Memory Trick: Remember the pituitary cowboy that sits in the sella turcica, his name is ROS. He is named ROS for the three foramina on either side; from medial to lateral: Rotundum , Ovale, Spinosum. His Legs go through Lacerum and his arms go through the optic canal. Optic Foramen or canal Foramen Rotondum Foramen Ovale Foramen Spinosum Foramen Lacerum Sella Turcica XLII. Facial bones Except for vomer and mandible, all facial bones are paired A. Maxilla 1. Anchors teeth: incisors, canines, premolars (bicuspids) and molars in dental alveoli 2. Palatine process – greater portion of hard palate 3. Incisive foramen 4. Infraorbital foramen – infraorbital nerve and artery 5. Maxillary sinus B. Palatine 1. Form posterior 1/3 of hard palate C. Zygomatic bone 1. Unites with temporal bone to form zygomatic arch D. Lacrimal bone 1. Smallest of facial bones 2. Groove houses nasolacrimal canal E. Nasal bones F. Inferior nasal concha – G. Vomer 1. Forms lower part of nasal septum 2. With the perpendicular plate, support nasal cartilage H. Mandible 1. Largest and strongest facial bone 2. Body – front and lateral sides 3. Rami – extend vertically from body 4. Condylar process – articulates with temporal bone 5. Coronoid process – attachment of temporalis muscle 6. Mandibular notch 7. Mental foramina – mental n and vessels 8. Mandibular foramen – inferior alveolar n and vessels I. Hyoid 1. Suspended from styloid process by stylohyoid muscles and ligaments 2. Supports tongue 36  3. Frequently fractured in strangulation J.Auditory Ossicles XLIII. Vertebral Column: You are responsible for specifics from text and in lab A. Functions 1. Support head and upper extremities 2. Provide attachment for muscles, ribs, organs 3. Protect the spinal cord B. Usually 33 vertebrae 1. 7 cervical 2. 12 thoracic 3. 5 lumbar 4. 5 (3-5) sacral - fused 5. 4 (3-5) coccyx – fused 6. Typically 26 movable parts C. General structure 1. Separated from each other by fibrocartilaginous intervertebral discs 2. Intervertebral foramina – openings between vertebrae through which spinal nerves pass 3. Body – anterior cylindrical portion 4. Vertebral foramen – houses part of spinal cord Vertebral pedicles – lateral wall of foramen } The pedicles and lamina form the vertebral Vertebral lamina – arched; connected to arch pedicles 5. Seven processes – a) The spinous process - bifurcated posterior process: for muscle attachment b) Two transverse processes: for muscle attachment c) Two superior articular processes: limit twisting d) Two inferior articular processes: limit twisting D. Spinal curves 1. Cervical 2. Thoracic 3. Lumbar 4. Sacral 5. Pathology a) Kyphosis exaggeration of normal thoracic curve b) Lordosis – exaggeration of the lumbar curve resulting in prominent abdomen and buttocks c) Scoliosis – abnormal lateral curve, most often seen in adolescent females XLIV. Rib Cage A. Sternum 1. 3 bones: manubrium, body, xiphoid process 2. Manubrium a) Jugular notch b) Clavicular notch c) Articulates with the costal cartilage of the 1st and 2nd ribs 37  3. Body a) Attaches to the 2nd through 10th ribs b) 8th, 9th, and 10th costal cartilages fuse to form the costal margin c) Costal angle where the costal cartilages come together with the xiphoid process 4. Xiphoid process a) Attachment for muscles b) Usually not ossified before age 25 B. Ribs 1. 12 pair 2. 7 pair anchored to sternum by individual costal cartilages: true ribs 3. Remaining 5 pair (8th – 12th) are false ribs 4. 11th and 12th don’t attach to sternum at all and are called floating ribs 5. Head and tubercle articulate with vertebrae 6. Neck constricted area between head and tubercle 7. Body – curved main part of rib 8. Costal groove – depressed inner canal that protects costal v and n 9. Costochondral joint 10. Intercostal spaces 38  Appendicular Skeleton XLV. Pectoral Girdle and Upper Extremity A. General 1. The pectoral girdle is composed of the scapulae and the clavicles. 2. The brachium is the upper arm 3. The antebrachium is the forearm 4. Wrist 5. Hand 6. The pectoral girdle is only attached to the axial skeleton at the sternoclavicular joint a) Allows wide range of movement b) Structurally more delicate B. The Clavicle: the “collar bone” 1. Slender S-shaped bone just deep to the skin 2. Sternal end: towards the sternoclavicular joint 3. Acromial end: towards the acromioclavicular joint: the junction with the scapula 4. Costal tuberosity: towards the sternal end - attachment site for shoulder ligaments 5. Conoid tubercle: towards the acromial end – attachment site for shoulder ligaments 6. Most frequently fractured bone C. The Scapula: the “shoulder blade” 1. Overlies ribs 2-7 2. The clavicular “spine” – strengthens the scapula, diagonal bony ridge on posterior surface 3. Spine broadens towards the shoulder as the acromion 4. Supraspinous fossa 5. Infraspinous fossa 6. Glenoid cavity: below acromion, where the humerus will fit 7. Coracoid process a) Anterior and superior to glenoid cavity b) Serves as the attachment for the biceps brachii 8. Acromion process a) Larger process, posterior b) Attachment site for part of the trapezius muscle c) Articulates with the clavicle – the acromioclavicular joint 9. Borders: superior, medial, and lateral The brachium extends from the shoulder to the elbow; in anatomy the arm strictly refers to the brachium D. Humerus: only bone of the brachium 1. Proximal head 2. Greater tubercle 3. Lesser tubercle 4. Intertubercular groove: biceps brachii muscle tendon passes through 5. Anatomical neck 6. Surgical neck – frequent site of fractures 7. Deltoid tuberosity – where deltoid inserts 39  8. Distally: Medial and lateral epicondyles 9. Capitulum: articulates with radius 10. Trochlea: articulates with ulna 11. Coronoid and olecranon fossae – allow movement of ulna E. Ulna: medial side of forearm 1. Trochlear notch articulates with humerus a) Coronoid process is anterior lip b) Olecranon is posterior lip 2. Radial notch accommodates head of radius 3. Distal end is tapered: the head 4. Styloid process is projection from head F. Radius: lateral side of forearm 1. Head is located proximally 2. Body enlarges distally 3. Tuberosity of radius: where biceps inserts 4. Distally: the styloid process and the ulnar notch Lateral epicondylitis – tennis elbow due to six extensor muscles of hand and wrist that originate here When falling, we naturally extend our hands to break the fall; frequent fractures of the radial head, neck or distal end (Colle’s) fracture can occur. It is less traumatic to pull appendages in, and let a larger body surface his the ground. Radial head dislocation or "pulled elbow": in children less than five, usually associated with forceful pulling of hand. Symptoms: immediate pain, and flexion of the elbow, with the child resisting extension. The treatment is firm supination of the hand with the elbow held at 90 flexion. The hand consists of 27 bones grouped into the carpus, metacarpus, and phalanges G. Carpus: the true wrist - eight carpal bones of wrist 1. Proximal row from lateral to medial a) Scaphoid: accounts for 70% of wrist fractures b) Lunate c) Triquetrum d) Pisiform 2. Distal a) Trapezium b) Trapezoid c) Capitate d) Hamate Mental trick: Scott Likes To Push The Toy Car Hard. Some Lovers Try Positions That They Can’t Handle Scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate 40  70% of wrist fractures occur to the scaphoid H. Metacarpal bones 1. One for each digit 2. Proximal base 3. Body 4. Distal head I. Phalanges (sing: phalanx) 1. 14 bones of the digits on each hand 2. Have a proximal, middle, and distal phalanx, except the thumb which lacks a middle phalanx 3. Digits numbered I-V 4. The thumb can be called the pollex XLVI. The Pelvic girdle and lower extremity The Pelvic girdle consists of two ossa coxae jointed anteriorly at the symphysis pubis and posteriorly to the sacrum The pelvis: divided by imaginary line from the sacral promontory to the upper margin of the symphysis pubis o Greater (false) pelvis: draw a circle from the base of the sacrum (that’s the top of the sacrum), along the arcuate lines of the ileum, to the top of the symphysis pubis. Everything above that is false, o Lesser (true) pelvis The acetabulum receives the head of the femur A. Ilium 1. The upper and largest of the pelvic bones 2. Iliac crest forms hip prominence 3. Anterior superior iliac spine: hip prominence in front, anterior termination of iliac crest 4. Anterior inferior iliac spine 5. Posterior superior iliac spine: posterior termination of iliac crest 6. Posterior inferior iliac spine 7. Just inferior to this is the greater sciatic notch, through which the sciatic nerve passes 8. Iliac tuberosity attachment of the sacroiliac ligament 9. Auricular surface articulates with the sacrum B. Ischium 1. Ischial tuberosity: bony projection that supports weight when we sit 2. Obturator foramen: covered by membrane and acts as site of attachment for muscles and viscera 3. Ramus – portion of the ischium that forms the foramen C. Pubis 1. Anterior bone of the os coxae 2. Superior ramus 3. Inferior ramus 4. Body D. Comparison of Male and Female Pelves Characteristics Male Female General structure Heavier; prominent processes Lighter; processes not so prominent 41  Pelvic inlet Heart shaped Round or oval Pelvic outlet Narrower Wider Ant sup iliac spines Not as wide apart Wider apart Obturator foramen Oval Triangular Acetabulum Faces laterally Faces more anteriorly Symphysis pubis Deeper longer Shallower, shorter Pubic arch Angle less than 90 Angle greater than 90 E. Femur 1. Technically only bone of thigh 2. Longest, heaviest, strongest bone of body 3. Head: articulates with the acetabulum a) Fovea capitis femoris: point of attachment of ligamentum teres 4. Neck: frequent site of fractures 5. Body: slight medial curve – brings knee into line with the center of gravity 6. Greater trochanter 7. Lesser trochanter 8. Medial condyle/ epicondyle 9. Lateral condyle / epicondyle F. Patella 1. Broad base 2. Inferiorly pointed apex 3. Since the patella is confined within the quadriceps tendon, it is more likely to be dislocated (laterally) than fractured The leg is technically only the portion of the lower limb between the knee and the foot G. Tibia 1. The shinbone – weight bearing bone of leg 2. Medial and lateral condyles articulates with condyles of femur 3. Intercondylar eminence 4. Tibial tuberosity: for attachment of the patellar ligament 5. Anterior crest: sharp ridge along anterior border 6. Medial malleolus: helps position the talus H. Fibula 1. Slender; important for muscle support and not weight bearing 2. Fibular head is proximal 3. Distally forms lateral malleolus The foot or pes, consists of 26 bones: grouped as tarsus, metatarsus, and phalanges. I. The Tarsus 1. Talus: articulates with tibia and fibula 2. Calcaneus: largest of tarsal bones and provides skeletal support for heel 3. Navicular bone: anterior to talus, and block shaped 4. Medial, intermediate, lateral cuneiform bones, and cuboid bone J.Metatarsus 42  1. Numbered I-V, medial to lateral 2. Base, body, and distal head K. Phalanges 1. 14 bones 2. Have proximal, middle, and distal phalanx 3. Except great toe (sing. hallucis or pl. hallux) which only has a proximal and distal phalanx L. Arches 1. Longitudinal: runs along length of foot 2. Transverse: width of the foot Polydactyly: extra digits Syndactyly: webbed digits Talipes: clubfoot: the sole of the foot is twisted medially Vocabulary Bone names and their structures: coracoid process, etc. Osteon Epiphysis Osteoblasts Canaliculi Diaphysis Articular cartilage Osteocytes Intramembranous Endosteum Metaphysis Osteoclasts Endochondral Medullary cavity Periosteum Lamellae Osteogenic Lacunae Study Suggestions 1. Be able to identify the bones, their significant features and functions. 2. Be able to identify the cranial cavities and foramina. 3. Be able to identify the fontanels and sutures. 4. Be able to identify the associated bones of the skull and their functions. 43 5. Know the vertebrae, types, and number of each. 6. Know the listed diseases of bone. 7. Know the bones of the pectoral and pelvic girdles. 8. Know the various inflammations and the