Skeletal System Anatomy & Physiology Unit VI PDF

ANA 1 ANATOMY AND PHYSIOLOGY A Mark Joseph V. Liwanag, MSN, RN Course facilitator  MODULE 6 SKELETAL SYSTEM  INTRODUCTION ▪ Human skeleton is the internal framework of the human ▪ is constructed of two of the most supportive tissues found in the human body— cartilage an...

ANA 1 ANATOMY AND PHYSIOLOGY A Mark Joseph V. Liwanag, MSN, RN Course facilitator  MODULE 6 SKELETAL SYSTEM  INTRODUCTION ▪ Human skeleton is the internal framework of the human ▪ is constructed of two of the most supportive tissues found in the human body— cartilage and bone. ▪ Ligaments - fibrous cords that bind the bones together at joints ▪ Joints - give flexibility and allow movement to occur. The skeleton is DIVIDED INTO TWO PARTS: 1. AXIAL SKELETON - the bones that form the longitudinal axis of the body 2. APPENDICULAR SKELETON - the bones of the limbs and girdles that attach them to the axial skeleton.  FUNCTIONS OF THE SKELETAL SYSTEM 1. SUPPORT ▪ Rigid, strong bone is well suited for bearing weight and is the major supporting tissue of the body. ▪ Cartilage provides a firm yet flexible support within certain structures ▪ Ligaments are strong bands of fibrous connective tissue that attach to bones and hold them together.  FUNCTIONS OF THE SKELETAL SYSTEM 2. PROTECTION. ▪ Bone is hard and protects the organs it surrounds. ▪ For example, the skull encloses and protects the brain, and the vertebrae surround the spinal cord. ▪ rib cage protects the heart, lungs, and other organs of the thorax. FUNCTIONS OF THE SKELETAL SYSTEM 3. MOVEMENT ▪ Skeletal muscles attach to bones by tendons, which are strong bands of connective tissue. ▪ Contraction of the skeletal muscles moves the bones, producing body movements. ▪ Joints, which are formed where two or more bones come together, allow movement between bones. FUNCTIONS OF THE SKELETAL SYSTEM 3. MOVEMENT ▪ Smooth cartilage covers the ends of bones within some joints, allowing the bones to move freely. ▪ Ligaments allow some movement between bones but prevent excessive movements.  FUNCTIONS OF THE SKELETAL SYSTEM 4. STORAGE. ▪ Some minerals in the blood are taken into bone and stored. ▪ are calcium and phosphorus. ▪ If blood levels of these minerals decrease, the minerals are released from bone into the blood. ▪ Fat (adipose tissue) is also stored within bone cavities: as a source of energy.  FUNCTIONS OF THE SKELETAL SYSTEM 5. BLOOD CELL PRODUCTION ▪ Many bones contain cavities filled with red bone marrow ▪ gives rise to blood cells and platelets BONE MATRIX ▪ bone, cartilage, tendons, and ligaments of the skeletal system are all connective tissues. ▪ mature bone - 35% organic and 65% inorganic material. ▪ organic material - collagen and proteoglycans. ▪ inorganic material - calcium phosphate  EXTRACELLULAR MATRIX ▪ COLLAGEN: is a tough, ropelike protein. ▪ PROTEOGLYCANS: are large molecules consisting of polysaccharides attached to core proteins ▪ similar to the way needles of a pine tree are attached to the tree’s branches. ▪ attract and retain large amounts of water between their polysaccharide “needles.” ▪ TENDONS and LIGAMENTS: contains large amounts of collagen fibers, EXTRACELLULAR MATRIX making these structures very tough, like ropes or cables. ▪ CARTILAGE: contains collagen and proteoglycans. ▪ Collagen makes cartilage tough, whereas the water-filled proteoglycans make it smooth and resilient. ▪ As a result: rigid, but it springs back to its original shape after being bent or slightly compressed ▪ Excellent shock absorber EXTRACELLULAR ▪ BONE: contains collagen and minerals, including calcium and MATRIX phosphate. ▪ ropelike collagen fibers, like the reinforcing steel bars in concrete, lend flexible strength to the bone. ▪ mineral component, like the concrete itself, gives the bone compression (weight-bearing) strength. ▪ mineral in bone is in the form of calcium phosphate crystals called HYDROXYAPATITE  GENERAL FEATURES OF BONE FOUR CATEGORIES OF BONE, based on their shape: 1. LONG BONES: are longer than they are wide. ▪ Most of the bones of the upper and lower limbs are long bones. 2. SHORT BONES: are approximately as wide as they are long ▪ examples are the bones of the wrist and ankle. GENERAL FEATURES OF BONE FOUR CATEGORIES OF BONE, based on their shape: 3. FLAT BONES: have a relatively thin, flattened shape. ▪ Examples of flat bones are certain skull bones, the ribs, the scapulae (shoulder blades), and the sternum. 4. IRREGULAR BONES: include the vertebrae and facial bones ▪ which have shapes that do not fit readily into the other three categories STRUCTURE OF A LONG BONE ▪ DIAPHYSIS: (growing between) central shaft of long bone ▪ EPIPHYSIS: (growing upon) the two end ▪ ARTICULAR CARTILAGE: A thin layer of cartilage, covers the ends of the epiphyses where the bone articulates (joins) with other bones. STRUCTURE OF A LONG BONE ▪ EPIPHYSEAL PLATE: composed of cartilage, between each epiphysis and the diaphysis ▪ is where the bone grows in length. ▪ EPIPHYSEAL LINE: When bone growth stops, the cartilage of each epiphyseal plate is replaced by bone STRUCTURE OF A LONG BONE ▪ MEDULLARY CAVITY: cavities in the bone, such as the large cavity in the diaphysis, as well as smaller cavities in the epiphyses of long bones. ▪ MARROW: soft tissue in the medullary cavities of the bone MARROW 1. YELLOW MARROW: ▪ consists mostly of adipose tissue. 2. RED MARROW: ▪ consists of blood-forming cells and is the only site of blood formation in adults ▪ Children’s bones have proportionately more red marrow than do adult bones STRUCTURE OF A LONG BONE ▪ PERIOSTEUM: outer surface of bone is covered by dense connective tissue; consists of two layers and contains blood vessels and nerves ▪ ENDOSTEUM: surface of the medullary cavity is lined with a thinner connective tissue membrane  1. OSTEOBLASTS: ▪ (bone-forming cells), which function in the formation of bone, as well as in the repair and remodeling of bone. ▪ produce collagen and proteoglycans, which are packaged into vesicles by the Golgi apparatus ▪ released from the cell by exocytosis. ▪ Ossification or osteogenesis is the formation of bone by osteoblasts. ▪ OSTEOCHONDRAL PROGENITOR CELLS: are stem cells that can become osteoblasts ▪ are located in the inner layer of the periosteum, and the endosteum. BONE CELLS BONE CELLS 2. OSTEOCYTES ▪ osteoblasts become surrounded by matrix (bone cells). ▪ it is a mature bone cell ▪ spaces occupied by the osteocyte cell bodies are called LACUNAE ▪ spaces occupied by the osteocyte cell processes are called CANALICULI 3. OSTEOCLAST: ▪ (bone-eating cells) are also present and contribute to bone repair and remodeling by removing existing bone. Bone tissue found throughout the skeleton is divided into two major types: ▪ COMPACT BONE: is mostly solid matrix and cells. ▪ SPONGY BONE: or cancellous bone, consists of a lacy network of bone with many small, marrow-filled spaces.  HISTOLOGY OF BONE: COMPACT BONE 1. COMPACT BONE or Cortical Bone ▪ Forms the perimeter of the diaphysis of a long bone ▪ Thinner surface of all other bone ▪ More matrix and is denser, with fewer pores ▪ Compose of predictable pattern of repeating units called OSTEONS ▪ osteon consists of concentric rings of LAMELLAE  HISTOLOGY OF BONE: COMPACT BONE ▪ HARVESIAN or CANTRAL CANAL – running parallel to the surface of the bone; small canals containing blood vessels (capillaries/arterioles/venules) ▪ LACUNAE – tiny cavities between two lamellae ▪ CANALUCULI – give osteon the appearance of having tiny cracks within the lamellae ▪ VOLKMANN’S or Perforating canals – canals running horizontally to harvesian canal, and also contain blood vessels  HISTOLOGY OF BONE: COMPACT BONE ▪ Nutrients leave the blood vessels of the central canals and diffuse to the osteocytes through the canaliculi. ▪ Waste products diffuse in the opposite direction. ▪ blood vessels in the central canals, in turn, are connected to blood vessels in the periosteum and endosteum.  2. SPONGY BONE ▪ Spongy bone, so called because of its appearance ▪ Very porous ▪ Located in the epiphyses of the long bone ▪ Less bone matrix ▪ More open space ▪ It forms the interior of all other bones.  2. SPONGY BONE: TRABECULA ▪ TRABECULAE - delicate interconnecting rods or plates of bone ▪ which resemble the beams or scaffolding of a building ▪ Add strength to the bone (scaffolding) ▪ Spaces filled with marrow. ▪ no blood vessels - no central canals. ▪ Nutrients exit vessels in the marrow and pass by diffusion (canaliculi to the osteocytes of the trabeculae)  BONE OSSIFICATION ▪ OSSIFICATION: is the formation of bone by osteoblasts. ▪ After an osteoblast becomes completely surrounded by bone matrix, it becomes a mature bone cell, or osteocyte. ▪ fetus begins at 3rd month of fetal age ▪ INTRAMEMBRANOUS OSSIFICATION: bone formation that occurs within connective tissue membranes ▪ ENDOCHONDRAL OSSIFICATION: bone formation that occurs inside cartilage ▪ Both types of bone formation result in compact and spongy bone.  ▪ occurs when osteoblasts begin to INTRAMEMBRANOUS produce bone in connective tissue OSSIFICATION membranes. ▪ primarily in the bones of the skull. ▪ Osteoblasts line up on the surface of connective tissue fibers and begin depositing bone matrix to form trabeculae. ▪ process begins in areas called ossification centers, and the trabeculae radiate out from the centers. ▪ trabeculae are constantly remodeled after their initial formation > compact bone ENDOCHONDRAL OSSIFICATION ▪ bones at the base of the skull and most of the remaining skeletal system develop through the process of endochondral ossification from cartilage models. ▪ cartilage models have the general shape of the mature bone ▪ chondrocytes, increase in number, enlarge, and die ▪ Then the cartilage matrix becomes calcified  ENDOCHONDRAL OSSIFICATION ▪ cartilage matrix becomes calcified ▪ occurring in the center of the cartilage model, blood vessels accumulate in the perichondrium. ▪ presence of blood vessels in the outer surface of future bone causes some of the unspecified connective tissue cells on the surface to become osteoblasts. ▪ osteoblasts then produce a collar of bone around part of the outer surface of the diaphysis, and the perichondrium becomes periosteum in that area. ENDOCHONDRAL OSSIFICATION ▪ Blood vessels also grow into the center of the diaphyses, bringing in osteoblasts and stimulating ossification. ▪ center part of the diaphysis, where bone first begins to appear, is called the primary ossification center ▪ Osteoblasts invade spaces in the center of the bone left by the dying cartilage cells. ENDOCHONDRAL OSSIFICATION ▪ calcified cartilage matrix is removed by osteoclasts, and the osteoblasts line up on the remaining calcified matrix and begin to form bone trabeculae. ▪ medullary cavity forms in the center of the diaphysis as osteoclasts remove bone ▪ calcified cartilage – replace by bone marrow. ▪ secondary ossification centers form in the epiphyses ENDOCHONDRAL OSSIFICATION  ▪ osteoblasts deposit new bone matrix on the surface of bones between the BONE GROWTH periosteum and the existing bone matrix, the bone increases in width, or diameter. ▪ process is called appositional growth. ▪ Growth in the length of a bone, which is the major source of increased height in an individual, occurs in the epiphyseal plate - occurs through endochondral ossification ▪ Bone elongation occurs at the epiphyseal plate as chondrocytes proliferate, enlarge, die, and are replaced by bone. Factors Affecting Bone NUTRITION Growth ▪ VITAMIN D - necessary for the normal absorption of calcium from the intestines ▪ The body can either synthesize or ingest vitamin D ▪ Insufficient vitamin D in children causes rickets ▪ RICKETS - a disease resulting from reduced mineralization of the bone matrix. ▪ Low vitamin D levels can be one cause of “adult rickets,” ▪ OSTEOMALACIA - a softening of the bones due to calcium depletion.  FACTORS AFFECTING BONE GROWTH ▪ VITAMIN C is necessary for osteoblasts to synthesize collagen. ▪ old collagen breaks down, new collagen is synthesized to replace it. ▪ deficiency results in bones and cartilage with fewer collagen fibers - collagen synthesis is impaired. ▪ In children, deficiency can retard growth. ▪ In both children and adults, deficiency can result in SCURVY, which is marked by ulceration and hemorrhage in almost any area of the body Factors Affecting Bone Growth: Hormones ▪ GROWTH HORMONE - from the anterior pituitary increases general tissue growth, including overall bone growth ▪ Excessive growth hormone secretion – GIGANTISM ▪ Insufficient growth hormone secretion results in - DWARFISM  FACTORS AFFECTING BONE GROWTH: HORMONES ▪ THYROID HORMONE - required for normal growth of all tissues, including cartilage ▪ a decrease in this hormone can result in a smaller individual ▪ ESTROGEN AND TESTOSTERONE cause increased bone growth and closure of the epiphyseal plate. ▪ During puberty, the levels of these hormones increase dramatically  BONE REMODELING ▪ Bone Remodeling: involves the removal of existing bone by osteoclasts and the deposition of new bone by osteoblasts. ▪ Bones are remodeled continually in response to changes in two factors: ▪ calcium ion level in the blood ▪ pull of gravity and muscles on the skeleton. ▪ Bone remodeling is essential, to retain normal proportions and strength during long-bone growth as the body increases in size and weight. ▪ bones become thicker and form large projections to increase their strength in areas where bulky muscles are attached  1. RESORPTION BONE REMODELLING ▪ Osteoclast remove bone mineral and matrix, creating erosion cavity (3-4 weeks) 2. REVERSAL ▪ Mononuclear cells prepare bone surface for new osteoblasts to begin building bone 3. FORMATION ▪ Osteoblasts synthesize a matrix to replace resorbed bone with new bone ( 3 – 4 months) 4. RESTING ▪ A prolonged resting period follows until a new remodelling begins  BONE REPAIR ▪ Sometimes a bone is broken and needs to be repaired. ▪ When this occurs, blood vessels in the bone are also damaged ▪ vessels bleed, and a clot (hematoma) forms in the damaged area  BONE REPAIR ▪ 2 - 3 days after the injury, blood vessels and cells from surrounding tissues begin to invade the clot. ▪ Some of these cells produce a fibrous network of connective tissue between the broken bones, which holds the bone fragments together and fills the gap between them. ▪ Other cells produce islets of cartilage in the fibrous network. ▪ network of fibers and islets of cartilage between the two bone fragments is called a callus BONE REPAIR ▪ Osteoblasts enter the callus and begin forming spongy bone ▪ Spongy bone formation in the callus is usually complete 4–6 weeks after the injury. ▪ Immobilization of the bone is critical up to this time ▪ Spongy bone is slowly remodeled to form compact and spongy bone, and the repair is complete BONE REPAIR  BONE FRACTURE ▪ five main categories of bone fractures CLASSIFICATION 1. mechanism of fracture 2. soft-tissue damage 3. displacement vs. non – displacement 4. fracture pattern 5. number of fragments in the fractured bone  MECHANISM OF FRACTURE The first criterion for bone fracture type falls under the category of the mechanism by which the fracture occurred. 1. through a trauma to the bone (TRAUMATIC) 2. through a pathology (disease) of the bone (PATHOLOGIC)  SOFT TISSUE DAMAGE The next criterion by which bone fractures are classified is by the amount of soft-tissue damage. 1. CLOSED (STABLE OR SIMPLE) - no visible damage to the skin at the injury site 2. OPEN (COMPOUND) - there is visible damage to the skin at the trauma site, possibly including a fragment of the fracture bone protruding from the skin. DISPLACED VS. NON - DISPLACED Two possibilities exist for the position of the fractured bone ends after the fracture has occurred: 1. DISPLACED - where the ends of the bones are offset from each other and are not aligned anatomically 2. NON – DISPLACED - where the ends of the bone remain in anatomical alignment.  This classification is based on the pattern of the fracture on the bone. These include: 1. Linear Fracture - runs parallel to the length of the bone FRACTURE PATTERN 2. Spiral Fracture - results from twisting of one part of the bone 3. Avulsion Fracture - separation of a bone fragment from the rest of the bone  FRACTURE PATTERN This classification is based on the pattern of the fracture on the bone. These include: 4. Stress (hairline) Fracture - incomplete fracture resulting from overuse of the bone 5. Compression Fracture - the bone collapses; common in spongy bone, often due to weakening of the bone such as in osteoporosis Number and Arrangement of Bone Fragments COMMINUTED Fractures are categorized by the completeness of the break 1. INCOMPLETE Fracture - a fracture that only traverses part of the bone 2. COMPLETE Fracture - a fracture that completely separates the bone into at least two fragments 3. COMMINUTED Fracture - a fracture where the bone breaks INCOMPLETE COMPLETE into multiple fragments  CALCIUM HOMEOSTASIS ▪ Bone is the major storage site for calcium in the body ▪ movement of calcium into and out of bone helps determine blood calcium levels ▪ Calcium (Ca2+) moves into bone as OSTEOBLASTS BUILD new bone and out of bone as OSTEOCLASTS BREAK down bone ▪ When osteoblast and osteoclast activity is balanced, the movements of calcium into and out of a bone are equal. CALCIUM HOMEOSTASIS 1. Decreased blood Ca2+ stimulates PTH secretion from parathyroid glands. 2. PTH stimulates osteoclasts to break down bone and release Ca2+ into the blood. 3. In the kidneys, PTH increases Ca2+ reabsorption from the urine. 4. PTH also stimulates active Vitamin D formation. Vitamin D promotes Ca2+ absorption from the small intestine into the blood. CALCIUM HOMEOSTASIS ▪ Increased blood Ca2+ stimulates calcitonin secretion from the thyroid gland. (5) ▪ Calcitonin inhibits osteoclasts, which allows for enhanced osteoblast uptake of Ca2+ from the blood to deposit into bone.(6)  CARTILAGES OF THE SKELETON Three cartilage tissue type: hyaline, elastic, and fibrocartilage. ▪ HYALINE CARTILAGE provides sturdy support with some flexibility. ▪ Most skeletal cartilages are composed of hyaline cartilage  CARTILAGES OF THE SKELETON ▪ ELASTIC CARTILAGE is much more flexible than hyaline cartilage, and it tolerates repeated bending. ▪ external ear and the epiglottis (which flops over and covers the larynx when we swallow) ▪ FIBROCARTILAGE has great tensile strength and can withstand heavy compression ▪ intervertebral discs and knee joint  The most important of the adult skeletal cartilages 1. ARTICULAR CARTILAGES, which cover the bone ends at movable joints 2. COSTAL CARTILAGES, which connect the ribs to the sternum (breastbone) 3. NASAL CARTILAGES, which support the external nose 4. INTERVERTEBRAL DISCS, which separate and cushion the vertebrae  GENERAL CONSIDERATIONS OF BONE ANATOMY ▪ Newborn human has 350 bones ▪ Adult human has 206 bones BONE MARKINGS Projections That Help Form Joints BONE MARKINGS BONE MARKINGS  AXIAL SKELETON AXIAL SKELETON can be divided into three parts: the SKULL, the VERTEBRAL COLUMN, and the THORACIC CAGE. This division of the skeleton forms the longitudinal axis of the body and PROTECTS: the brain, spinal cord, heart, and lungs.  SKULL ▪ Sits on top of the vertebral column ▪ Two sets of bones ▪ Cranium (8 bones) ▪ Facial bones (14 bones) ▪ Bones are joined by sutures ▪ Only the mandible is attached by a freely movable joint  CRANIUM DIVIDED INTO TWO MAJOR AREAS 1. CRANIAL VAULT, OR CALVARIA - forming the superior, lateral, and posterior walls of the skull 2. CRANIAL BASE - forming the skull bottom. FRONTAL BONE (1) - Forms the forehead, superior part of the orbit, and the floor of the anterior cranial fossa  PARIETAL BONE (2) Form the superior and lateral aspects of the skull. TEMPORAL BONES (2) ▪ Form the inferolateral aspects of the skull ▪ sides of the head, close to ears. ▪ Commonly called the temples ▪ Includes the external auditory meatus ▪ Opening for the ear ▪ Includes the zygomatic process ▪ Part of the cheekbone OCCIPITAL BONE ▪ Forms the posterior aspect and most of the base of the skull. ▪ back and base of the cranium ▪ FORAMEN MAGNUM - Large opening in the base of the bone, which allows the spinal cord to join with the brain stem. SPHENOID BONE (1) ▪ Bat-shaped bone that is described as the keystone bone of the cranium because it articulates with all other cranial bones. ▪ parts of orbits of the eyes ▪ Includes Sella Turcica - here pituitary gland sits ▪ OPTIC CANALS - cranial nerve II (optic nerve) passes through to serve the eye. ▪ FORAMEN ROTUNDUM - a branch of cranial nerve V (maxillary division) passes through. ▪ FORAMEN OVALE - a branch of cranial nerve V (mandibular division) passes through. ▪ FORAMEN SPINOSUM - provides passageway for the middle meningeal artery  ETHMOID (1) ▪ Contributes to the anterior cranial fossa ▪ forms part of the nasal septum and the nasal cavity ▪ contributes to the medial wall of the orbit. MAJOR SUTURES (4) ▪ SAGITTAL SUTURE: Occurs where the left and right parietal bones meet superiorly in the midline of the cranium ▪ LAMBDOID SUTURE: Occurs where the parietal bones meet the occipital bone posteriorly  MAJOR SUTURES (4) ▪ SQUAMOUS SUTURE: Occurs where each parietal bone meets the temporal bone, on each lateral aspect of the skull ▪ CORONAL SUTURE: Running in the frontal plane, occurs anteriorly where the parietal bones meet the frontal bone ▪ CRANIAL BASE has three distinct depressions: the ANTERIOR, MIDDLE, AND POSTERIOR cranial fossae ▪ The BRAIN sits in these fossae, completely enclosed by the cranial vault. FACIAL BONES ▪ NASAL (2) - Small rectangular bones forming the bridge of the nose. ▪ LACRIMAL (2) - Each forms part of the medial orbit in between the maxilla and ethmoid bone. ▪ ZYGOMATIC (2) - Commonly called the cheekbones; each forms part of the lateral orbit FACIAL BONES INFERIOR NASAL CONCHA (2) ▪ each forms part of the lateral walls of the nasal cavities ▪ improves the airflow through the nasal cavity MAXILLA (2) ▪ Keystone facial bones because they articulate with all other facial bones except the mandible ▪ form the upper jaw and parts of the hard palate, orbits, and nasal cavity. Inferior view of the skull, mandible removed PALATINE (2) ▪ Forms the posterior hard palate, a small part of the nasal cavity, and part of the orbit. VOMER (1) ▪ Thin, blade-shaped bone that forms the inferior nasal septum. FACIAL BONES MANDIBLE (1) ▪ lower jawbone, which articulates with the temporal bone ▪ carries the lower teeth ▪ anterior portion forms the chin ▪ Only freely movable joint in the skull  Failure of the palatine and/or maxillary bones to fuse causes a CLEFT PALATE. PARANASAL SINUSES ▪ the sinuses found in the frontal bone, the ethmoid bone, the sphenoid bone, and the maxilla bone ▪ sinuses are openings within particular bones that open into the nasal cavity. sinuses have two major functions: ▪ they decrease the weight of the skull ▪ they act as a resonating chamber when speaking.  HYOID BONE ▪ U shaped ▪ Found in the upper neck ▪ The only bone that does not articulate with another bone ▪ It serves as a point of attachment for many tongue and neck muscles.  THE FETAL SKULL ▪ Fontanelles –are the spaces or opening where the skull bones join ▪ ANTERIOR FONTANELLE – located at the junction of two parietal bones. It is a diamond in shape ▪ POSTERIOR FONTANEL –located at the junction of parietal bones and occipital bone. It is a triangular in shape  FETAL SKULL ▪ Allow the brain to grow ▪ Convert to bone within 24 months after birth ▪ ANTERIOR FONTANELLE – normally closes at 12 to 18th months of age ▪ POSTERIOR FONTANELLE - Closes by the end of the second month  ▪ 3 Tiny bones - transmit vibrations ▪ All derived from Latin words MIDDLE EAR ▪ Malleus (hammer), Incus (anvil) and Stapes (stirrup) ▪ Smallest bone in the body THE VERTEBRAL COLUMN VERTEBRAL COLUMN ▪ extending from the skull to the pelvis ▪ forms the body’s major axial support. ▪ it surrounds and protects the delicate spinal cord ▪ column consists of 24 single bones called VERTEBRAE and two composite, or fused, bones (the sacrum and coccyx) THE VERTEBRAL COLUMN ▪ 7 bones of the neck are called cervical vertebrae ▪ the next 12 are thoracic vertebrae a ▪ 5 supporting the lower back are lumbar vertebrae. Remembering common mealtimes for breakfast, lunch, and dinner (7 a.m., 12 noon, and 5 p.m.)  VERTEBRAL COLUMN INTERVERTEBRAL DISC ▪ separate the vertebrae ▪ pads of fibrocartilage that cushion the vertebrae and absorb shocks. 2 MAJOR REGIONS 1. NUCLEUS PULPOSUS - a central gelatinous that behaves like a rubber ball 2. ANULUS FIBROSUS - an outer ring of encircling collagen fibers that stabilizes the disc STRUCTURE OF A TYPICAL VERTEBRA Although they differ in size and specific features, all vertebrae have some features in common ▪ BODY (OR CENTRUM): Rounded central portion of the vertebra, which faces anteriorly in the human vertebral column. ▪ VERTEBRAL ARCH: Composed of pedicles, laminae, and a spinous process, it represents the junction of all posterior extensions from the vertebral body. ▪ VERTEBRAL (SPINAL) FORAMEN: Opening enclosed by the body and vertebral arch; a passageway for the spinal cord. STRUCTURE OF A TYPICAL VERTEBRA ▪ TRANSVERSE PROCESSES: Two lateral projections from the vertebral arch. ▪ SPINOUS PROCESS: Single medial and posterior projection from the vertebral arch. ▪ SUPERIOR AND INFERIOR ARTICULAR PROCESSES: Paired projections lateral to the vertebral foramen that enable articulation with adjacent vertebrae. ▪ INTERVERTEBRAL FORAMINA: openings, for spinal nerves to leave the spinal cord between adjacent vertebrae. CERVICAL VERTEBRAE ▪ seven cervical vertebrae (referred to as C1 through C7) form the neck portion of the vertebral column. ▪ first two cervical vertebrae (atlas and axis) are highly modified to perform special functions ATLAS (C1) ▪ lacks a body ▪ its lateral processes contain large concave depressions on their superior surfaces that receive the occipital condyles of the skull. ▪ this joint enables you to nod ▪ OCCIPITAL CONDYLES –rests on the first vertebra of the vertebral column  CERVICAL VERTEBRAE AXIS (C2) ▪ acts as a pivot for the rotation of the atlas (and skull) above. ▪ It bears a large vertical process, the dens, that serves as the pivot point. ▪ articulation between C1 and C2 allows you to rotate your head from side to side  CERVICAL VERTEBRAE The more typical cervical vertebrae (C3 through C7) are distinguished from the thoracic and lumbar vertebrae by several features ▪ are the smallest, lightest vertebrae ▪ vertebral foramen is triangular. ▪ spinous process is short and often bifurcated (divided into two branches).  CERVICAL VERTEBRAE ▪ spinous process of C7 is not branched ▪ substantially longer than that of the other cervical vertebrae. ▪ spinous process of C7 is visible through the skin at the base of the neck ▪ it is called the VERTEBRA PROMINENS and is used as a landmark for counting the vertebrae. ▪ Transverse processes of the cervical vertebrae are wide ▪ contain foramina through which the vertebral arteries pass superiorly on their way to the brain. THORACIC VERTEBRAE ▪ 12 thoracic vertebrae (referred to as T1 through T12) ▪ have a larger body than the cervical vertebrae ▪ body is somewhat heart shaped ▪ vertebral foramen is oval or round, and the spinous process is long, with a sharp downward hook. ▪ forming the thoracic part of the spine  ▪ form the posterior aspect of the thoracic cage THORACIC ▪ only vertebrae that articulate with the ribs. VERTEBRAE ▪ Articular facets on the transverse processes articulate with the tubercles of the ribs.  LUMBAR VERTEBRAE ▪ five lumbar vertebrae (L1 through L5) ▪ support the majority of the body’s weight ▪ they have massive bodies and heavy, rectangular transverse and spinous processes. ▪ superior articular facets face posteromedially; the inferior ones are directed anterolaterally. ▪ adds strength to the inferior portion of the vertebral column and limits rotation of the lumbar vertebrae.  THE SACRUM ▪ is a composite bone formed from the fusion of five vertebrae ▪ Superiorly - articulates with L5 ▪ Inferiorly - connects with the coccyx. ▪ located between the two hip bones ▪ It articulates with each hip bone by way of the auricular surfaces, forming the sacroiliac joint ▪ As part of the pelvic girdle, it provides stable support for our lower limbs. THE COCCYX ▪ is formed from the fusion of three to five small irregularly shaped vertebrae. ▪ literally the human tailbone ▪ coccyx is attached to the sacrum by ligaments.  THE THORACIC CAGE ▪ consists of the bony thorax, which is composed of the sternum, ribs, and thoracic vertebrae, plus the costal cartilages ▪ Its cone-shaped, cagelike structure protects the organs of the thoracic cavity, including the critically important heart and lungs.  THORACIC CAGE STERNUM (BREASTBONE), a typical flat bone ▪ is a result of the fusion of three bones—the manubrium, body, and xiphoid process. ▪ It is attached to the first seven pairs of ribs. 1. MANUBRIUM – superior most; looks like the knot of a tie; it articulates with the clavicle (collarbone) laterally. 2. BODY - forms the bulk of the sternum. 3. XIPHOID PROCESS - constructs the inferior end of the sternum and lies at the level of the fifth (1) The manubrium (handle) is the intercostal space. “sword handle”; (2) the body, or gladiolus (sword), is the ▪ made of hyaline cartilage in children, it is “blade” usually ossified in adults over the age of 40. (3) (3) the xiphoid process is the “sword tip.”  THE RIBS ▪ 12 pairs of ribs form the walls of the thoracic cage ▪ articulate posteriorly with the vertebral column via their heads and tubercles ▪ First seven pairs, called the true, or VERTEBROSTERNAL, ribs, attach directly to the sternum by their “own” costal cartilages. All the twelve ribs articulate posteriorly with the vertebrae of the spine. Each rib forms two joints: ▪ Costotransverse joint – Between the tubercle of the rib, and the transverse costal facet of the corresponding vertebrae. ▪ Costovertebral joint – Between the head of the rib, superior costal facet of the corresponding vertebrae, and the inferior costal facet of the vertebrae above.  THE RIBS ▪ next five pairs are called FALSE RIBS; they attach indirectly to the sternum or entirely lack a sternal attachment. ▪ 8–10, which are also called VERTEBROCHONDRAL ribs, have indirect cartilage attachments to the sternum via the costal cartilage of rib 7. ▪ 11 - 12, called floating, or vertebral, ribs, have no sternal attachment.  APPENDICULAR SKELETON ▪ composed of the 126 BONES ▪ appendages and the pectoral and pelvic girdles, which attach the limbs to the axial skeleton.  PECTORAL GIRDLE ▪ Also called the shoulder girdle ▪ consists of two pairs of bones 4 bones; 2 scapulae + 2 clavicles ▪ attach the upper limbs to the axial skeleton and provide attachment points for many trunk and neck muscles. ▪ is exceptionally light and allows the upper limb a degree of mobility  PECTORAL GIRDLE: SCAPULA ▪ SCAPULA - commonly known as the shoulder blade ▪ is a flat, triangular bone that can easily be seen and felt in a living person ▪ ACROMION PROCESS - form the point of the shoulder; attachment points for some of the shoulder muscles. ▪ GLENOID CAVITY - located in the superior lateral portion of the bone, articulates with the head of the humerus.  PECTORAL GIRDLE: CLAVICLE ▪ CLAVICLE - commonly known as the collarbone ▪ is a long bone with a slight sigmoid (S-shaped) curve. ▪ It articulates with the scapula and the sternum. ▪ lateral end it articulates with the acromion process. ▪ medial end it articulates with the manubrium of the sternum. ▪ clavicle holds the upper limb away from the body, it facilitates the limb’s mobility  ARM/BRACHIUM ▪ contains a single bone - HUMERUS. ▪ Proximally its rounded head fits into the shallow glenoid cavity of the scapula. ▪ head is separated from the shaft by the anatomical neck and the more constricted surgical neck - which is a common site of fracture. ▪ Capitulum - rounded lateral condyle that articulates with the radius ▪ Trochlea - flared medial condyle that articulates with the ulna FOREARM/ANTEBRACHIUM The forearm has two bones: ▪ ulna and radius ▪ ULNA - is medial, the same side as the little finger ▪ Radius - is lateral, the same side as the thumb. ▪ ulna and radius articulate with the humerus at the elbow joint. ULNA ▪ TROCHLEAR NOTCH - C-shaped portion of the ulna that articulates with the humerus is the ▪ rotates over the trochlea of the humerus when bending the elbow. RADIUS ▪ HEAD - portion of the radius that articulates with the humerus ▪ rotates over the capitulum of the humerus when bending the elbow.  HAND/ MANUS: WRIST ▪ wrist is a relatively short region between the forearm and the hand ▪ composed of eight carpal bones arranged into two rows of four each ❖ proximal row of carpal bones, lateral to medial 1. SCAPHOID - boat-shaped 2. LUNATE - moon-shaped 3. TRIQUETRUM - three-cornered 4. PISIFORM - pea-shaped  HAND/ MANUS: WRIST ▪ distal row of carpal bones, from medial to lateral 1. HAMATE - has a hooked process on its palmar side 2. CAPITATE - head-shaped 3. TRAPEZOID - named for its resemblance to a four-sided geometric form two parallel sides 4. TRAPEZIUM - named after a four- sided geometric form with no two sides parallel.  HAND: METACARPALS METACARPALS – PALM ▪ 5 metacarpal bones - attached to the carpal bones ▪ central portion of the hand ▪ in the resting position, the palm of the hand is concave. ▪ distal ends of the metacarpal bones help form the knuckles of the hand  HAND: PHALANGES ▪ five digits of each hand include one thumb (pollex) and four fingers. ▪ digit consists of small long bones called PHALANGES ▪ thumb has two phalanges, called proximal and distal. ▪ Each finger has three phalanges, designated proximal, middle, and distal.  PELVIC GIRDLE ▪ formed by the two hip bones and the sacrum. ▪ are heavy and massive, and they attach securely to the axial skeleton. 1. ILIUM – most superior 2. ISCHIUM – inferior and posterior; sit down bone 3. PUBIS – inferior and anterior  PELVIC GIRDLE ▪ PUBIC SYMPHYSIS – where coxal bones join anteriorly ▪ SACROILIAC JOINTS – joins the sacrum posteriorly ▪ ACETABULUM – socket of the hip joint ▪ OBTURATOR FORAMEN – large hole in each coxal bone ▪ Male pelvis: larger and massive; Female pelvis; broader FEMALE PELVIS MALE PELVIS LOWER LIMBS: THIGH ▪ Femur – thigh bone ▪ heaviest, strongest bone in the body. ▪ HEAD OF THE FEMUR – articulates with the acetabulum of the coxal bone ▪ CONDYLES – articulates with the tibia ▪ EPIDONDYLES – points of ligaments attachments  LOWER LIMB: THIGH ▪ PATELLA - knee cap ▪ Triangular bone located within a tendon that passes over the knee.  LOWER LIMB: LEGS ▪ 2 bones, the TIBIA and the FIBULA, form the skeleton of the leg ▪ TIBIA, or shinbone - is the larger, medial, weight-bearing bone of the leg. ▪ MEDIAL CONDYLE - Slightly concave surface that articulates with the medial condyle of the femur ▪ FIBULA – thin and sticklike that forms the lateral ▪ lies parallel to the tibia, takes no part in forming the knee joint. ▪ proximal head articulates with the lateral condyle of the tibia. LOWER LIMB: ANKLE ▪ consists of the distal ends of the tibia and fibula forming a partial socket that articulates with a bone of the foot (the talus) ▪ A prominence can be seen on each side of the ankle ▪ These are the medial malleolus of the distal tibia and the lateral malleolus of the distal fibula. LOWER LIMB: FOOT ❖ Tarsal (7) – ankle ❖ Metatarsals (5) – sole ❖ Phalanges (14) – toes  7 TARSAL BONES include: 1. Talus 2. Calcaneus 3. Navicular 4. Media cuneiforms 5. Intermediate cuneiforms 6. Lateral cuneiforms 7. Cuboid MNEMONIC - Tiger Cub Needs MILC (Talus, Calcaneus, Navicular, Medial cuneiform, Intermediate cuneiform, Lateral cuneiform, and Cuboid).  LOWER LIMB: FOOT ▪ Body weight is concentrated on the two largest tarsals, which form the posterior aspect of the foot. ▪ larger calcaneus (heel bone) and the talus ▪ metatarsals are numbered I through V, medial to lateral. ▪ toe has 3 phalanges except the great toe, which has 2.  LOWER LIMB: FOOT ▪ bones in the foot are arranged to produce three strong arches ▪ two longitudinal arches (medial and lateral) and one transverse arch 2 main functions of the foot: 1. to support the body in its upright position both while standing and in forward movement during walking 2. to push the body forward during walking and to absorb shock when the foot contacts the ground.  ARTICULATIONS/JOINTS 2 FUNCTIONS FOR THE BODY. 1. hold the bones together 2. allow the rigid skeletal system some flexibility so that gross body movements can occur. ▪ Ways joints are classified ▪ By their function ▪ By their structure FUNCTIONAL CLASSIFICATION OF JOINTS ▪ Synarthroses – immovable joints ▪ Amphiarthroses – slightly moveable joints ▪ Diarthroses – freely moveable joints STRUCTURAL CLASSIFICATION OF JOINTS ▪ Fibrous joints - Generally immovable ▪ Cartilaginous joints - Immovable or slightly moveable ▪ Synovial joints - Freely moveable  FIBROUS JOINTS ▪ 2 bones that are united by fibrous tissue ▪ Exhibit little or no movement 1. SUTURES – bet. the bones of the skull; squamous, lambdoid, coronal 2. SYNDESMOSES – bones are separated by some distance and held together by ligaments; radius and ulna 3. GOMPHOSES – consists of pegs fitted into sockets and held in place by ligaments; joint bet. a tooth and its socket  CARTILAGINOUS JOINTS Unites two bones by means of cartilage Slight movement can occur 1. SYNCHONDROSIS (HYALINE CARTILAGE) ▪ costal cartilage of rib 1 and the sternum ▪ epiphyseal plate in growing long bones ▪ Synarthrosis (immovable) 2. SYMPHYSIS (FIBROCARTILAGE) ▪ Intervertebral discs between adjacent vertebrae ▪ anterior connection between the pubic bones ▪ Amphiarthrosis (slightly movable)  SYNOVIAL JOINTS ▪ Freely movable joints ▪ Contains fluid in a cavity surrounding the ends of articulating bones ▪ Reinforced by ligaments  Synovial joints typically have the following structural characteristics ▪ JOINT (ARTICULAR) CAVITY: A space between the articulating bones. The cavity is filled with synovial fluid. ▪ ARTICULAR CARTILAGE: Hyaline cartilage that covers the surfaces of the bones forming the joint. ▪ ARTICULAR CAPSULE: Two layers that enclose the joint cavity. 1. external layer is the fibrous layer composed of dense irregular connective tissue 2. inner layer is the synovial membrane composed of loose connective tissue.  Synovial joints typically have the following structural characteristics ▪ SYNOVIAL FLUID: A viscous fluid, the consistency of egg whites, located in the joint cavity - fluid acts as a lubricant ▪ REINFORCING LIGAMENTS: Synovial joints are reinforced by ligaments outside and inside the articular capsule ▪ NERVES AND BLOOD VESSELS: Sensory nerve fibers detect pain and joint stretching. ▪ Most of the blood vessels supply the synovial membrane.  6 TYPES OF SYNOVIAL JOINTS 1. HINGE JOINT ▪ permit movement in one plane only ▪ elbow and knee joints  6 TYPES OF SYNOVIAL JOINTS 2. BALL AND SOCKET JOINTS ▪ consist of a ball (head) and a socket ▪ Bones can move in many directions ▪ shoulder and hip joints 6 TYPES OF SYNOVIAL JOINTS 3. PIVOT JOINTS ▪ restrict movement to rotation around a single axis ▪ rotation that occurs bet. the axis and atlas ▪ articulation bet. the ulna and radius 6 TYPES OF SYNOVIAL JOINTS 4. PLANE/GLIDING JOINTS ▪ two opposed flat surfaces that glide over each other Limited but complex movement Between tarsal bone 6 TYPES OF SYNOVIAL JOINTS 5. Saddle Joints ▪ two saddle shaped articulating surfaces oriented at right angles ▪ joint bet. the metacarpal bone and the carpal bone of the thumb 6 TYPES OF SYNOVIAL JOINTS 6. Ellipsoid/Condyloid Joints ▪ elongated ball and socket joints ▪ joint bet. the occipital condyles (skull) and the atlas (vertebral column) ▪ joints bet. the metacarpals and phalanges TYPES OF BODY MOVEMENT FLEXION. is a movement, generally in the sagittal plane, that decrease the angle of the joint and brings two bones closer together EXTENSION. the opposite of flexion, so it is a movement that increases the angle, or the distance, between two bones or parts of the body. TYPES OF BODY MOVEMENT Rotation. is movement of a bone around a longitudinal axis; it is a common movement of ball-and-socket joints. TYPES OF BODY MOVEMENT ABDUCTION. is moving the limb away from the midline, or median plane, of the body. ADDUCTION. is the opposite of abduction, so it is the movement of a limb toward the body midline. TYPES OF BODY MOVEMENT Circumduction. is a combination of flexion, extension, abduction, and adduction commonly seen in ball-and-socket joints; the proximal end is stationary, and its distal end moves in a circle.  TYPES OF BODY MOVEMENT ▪ SUPINATION occurs when the forearm rotates laterally so that the palm faces anteriorly and the radius and ulna are parallel ▪ PRONATION occurs when the forearm rotates medially so that the palm faces posteriorly. ▪ OPPOSITION. In the palm of the hand, the saddle joint between metacarpal 1 and the carpals allows opposition of the thumb.  TYPES OF BODY MOVEMENT INVERSION AND EVERSION. To invert the foot, turn the sole medially; to evert the foot, turn the sole laterally. DORSIFLEXION AND PLANTAR FLEXION. Lifting the foot so that its superior surface approaches the shin is called dorsiflexion, whereas depressing the foot is called plantar flexion. REFERENCES: VanPutte C. et.al. (2019). Seeley’s Essentials of Anatomy & Physiology. 10th edition. New York: McGraw Hill Co. Inc.