AnaphysioLEC Midterm 2 - Skeletal System - Anatomy and Physiology - PDF

INTRODUCTION TO SKELETAL Long bones (humerus) Typically longer than they are wide SYSTEM Shaft with enlarged end...

INTRODUCTION TO SKELETAL Long bones (humerus) Typically longer than they are wide SYSTEM Shaft with enlarged ends Contain mostly compact bone; spongy bone at ends ANATOMY AND PHYSIOLOGY All of the bones of the limbs (except wrist, ankle, and kneecap bones) are long bones Examples: Femur Humerus THE SKELETAL SYSTEM Parts of the skeletal system Flat bones (sternum) Thin, flattened, and usually curved Bones (skeleton) Two thin layers of compact bone sandwich a layer of spongy bone between them Joints Examples: Most bones of the skull Ribs Sternum Cartilages Short Bones (talus) Generally cube-shaped Ligaments Contain mostly spongy bone with an outer layer of compact bone Sesamoid bones are a type of short bone that form within tendons Two subdivisions of the skeleton (patella) Examples: Carpals (wrist bones) Tarsals (ankle bones) 1. Axial skeleton Irregular bones (vertebra), right lateral view 2. Appendicular skeleton Irregular shape Do not fit into other bone classification categories Examples: Vertebrae Hip bones FUNCTION OF BONES Support the body Protect soft organs - Skull and vertebrae protect brain and spinal cord STRUCTURE OF BONES - Rib cage protects thoracic cavity organs Attached skeletal muscles allow movement Long bone anatomy Store minerals and fats Diaphysis (shaft) - Calcium and phosphorus - Fat in the internal marrow cavity - Makes up most of bone’s length Blood cell formation (hematopoiesis) -Composed of compact bone Periosteum CLASSIFICATION OF BONES - Outside covering of the diaphysis The adult skeleton has 206 bones - Fibrous connective tissue membrane Two basic types of osseous (bone) tissue - Perforating (Sharpey’s) fibers secure periosteum to 1. Compact bone underlying bone - Dense, smooth, and homogeneous 2. Spongy bone - Small needlelike pieces of bone - Many open spaces Bones are classified on the basis of shape into four groups Long Flat Short Irregular  - Terms often begin with “F” Long bone anatomy (continued) Epiphysis (ends) - Composed mostly of spongy bone enclosed by thin layer of compact bone Articular cartilage - Covers the external surface of the epiphyses - Made of hyaline cartilage - Decreases friction at joint surfaces Long bone anatomy (continued) Epiphyseal line - Remnant of the epiphyseal plate - Seen in adult bones Epiphyseal plate - Flat plate of hyaline cartilage seen in young, growing bone Structure of Bone - Causes lengthwise growth of a long bone Microscopic anatomy of spongy bone - Composed of small, needlelike pieces of bone Long bone anatomy (continued) called Trabeculae and open spaces Endosteum - Open spaces are filled by marrow, blood vessels, - Lines the inner surface of the shaft and nerves - Made of connective tissue Medullary cavity Microscopic anatomy of compact bone - Cavity inside the shaft Osteocytes - Contains yellow marrow (mostly fat) in adults - Mature bone cells situated in bone matrix - Contains red marrow for blood cell formation in Lacunae infants until age 6 or 7 - Cavities in bone matrix that house osteocytes Bone markings Lamellae - Sites of attachments for muscles, tendons, and - Concentric circles of lacunae situated around the ligaments central (Haversian) canal - Passages for nerves and blood vessels Categories of bone markings Microscopic anatomy of compact bone (continued) - Projections or processes-grow out from the Central (Haversian) canal bone surface - Opening in the center of an osteon (Haversian - Terms often begin with “T” system) Depressions or cavities-indentations - Runs lengthwise through bone - Carries blood vessels and nerves Osteon (Haversian system) By birth, most cartilage is converted to bone except for - A unit of bone containing central canal and matrix two regions in a long bone rings Structural and functional unit of compact 1. Articular cartilages bone 2. Epiphyseal plates New cartilage is formed continuously on external face Microscopic anatomy of compact bone (continued) of these two cartilages Canaliculi Old cartilage is broken down and replaced by bony - Tiny canals matrix - Radiate from the central canal to lacunae - Form a transport system connecting all bone cells Appositional growth to a nutrient supply - Bones grow in width Perforating (Volkmann’s) canal - Osteoblasts in the periosteum add bone matrix to - Canal perpendicular to the central canal the outside of the diaphysis - Carries blood vessels and nerves - Osteoclasts in the endosteum remove bone from the inner surface of the diaphysis Bone growth is controlled by hormones, such as growth hormone and sex hormones Bone is relatively lightweight and resists tension and other forces Bones are remodeled throughout life in response to two Organic parts (collagen fibers) of the bone make bone factors flexible and have great tensile strength 1. Calcium ion level in the blood determines when bone Calcium salts deposited in the bone make bone hard to matrix is to be broken down or formed resist compression 2. Pull of gravity and muscles on the skeleton determines where bone matrix is to be broken down or formed Bone Formation, Growth, and Remodeling Calcium ion regulation Bone formation and growth Parathyroid hormone (PTH) - Ossification is the process of bone formation - Released when calcium ion levels in blood are low Occurs on hyaline cartilage models or fibrous - Activates osteoclasts (bone-destroying cells) membranes - Osteoclasts break down bone and release calcium - Long bone growth involves two major phases ions into the blood Hypercalcemia (high blood calcium levels) prompt Two major phases of ossification in long bones calcium storage to bones by osteoblasts 1. Osteoblasts (bone-forming cells) cover hyaline cartilage model with bone matrix BONE FRACTURES 2. In a fetus, the enclosed cartilage is digested away, Fracture: break in a bone opening up a medullary cavity Types of bone fractures Closed (simple) fracture is a break that does not penetrate the skin Open (compound) fracture is a broken bone that penetrates through the skin Bone fractures are treated by reduction and immobilization - Closed reduction: bones are manually coaxed into position by physician’s hands - Open reduction: bones are secured with pins or wires during surgery Healing time is 6-8 weeks  SKULL Repair of bone fractures involves four major events Two sets of bones form the skull Hematoma (blood-filled swelling, or bruise) is formed 1. Cranium bones enclose the brain Fibrocartilage callus forms 2. Facial bones - Cartilage matrix, bony matrix, collagen fibers - Hold eyes in anterior position splint the broken bone - Allow facial muscles to express feelings Bony callus replaces the fibrocartilage callus Bones are joined by sutures - Osteoblasts and osteoclasts migrate in Bone Only the mandible is attached by a freely movable remodeling occurs in response to mechanical joint stresses 8 cranial bones protect the brain 1 Frontal bone 2 Occipital bone 3 Ethmoid bone 4 Sphenoid bone 5, 6 Parietal bones (pair) 7, 8 Temporal bones (pair) 14 facial bones 1, 2 Maxillae (pair) 3, 4 Palatine bones (pair) 5, 6 Lacrimal bones (pair) Axial Skeleton 7, 8 Zygomatic bones (pair) Forms the longitudinal axis of the body Divided into 9, 10 Nasal bones (pair) three parts 11 Vomer bone 1. Skull 12, 13 Inferior nasal conchae (pair) 2. Vertebral column 14 Mandible 3. Bony thorax Paranasal sinuses - Hollow portions of bones surrounding the nasal cavity Functions of paranasal sinuses - Lighten the skull - Amplify sounds made as we speak  Vertebral Column (Spine) Primary curvatures - Spinal curvatures of the thoracic and sacral regions - Present from birth - Form a C-shaped curvature in newborns Hyoid bone Secondary curvatures - Closely related to mandible and temporal bones - Spinal curvatures of the cervical and lumbar - The only bone that does not articulate with regions another bone - Develop after birth - Serves as a movable base for the tongue - Form an S-shaped curvature in adults - Aids in swallowing and speech Parts of a typical vertebra - Body (centrum) - Vertebral arch Pedicle Lamina Vertebral foramen Transverse processes Spinous process Superior and inferior articular processes Vertebral Column (Spine) Vertebral column provides axial support THORACIC CAGE - Extends from skull to the pelvis 26 vertebral bones are separated by intervertebral Bony thorax, or thoracic cage, protects organs of the thoracic cavity discs Consists of three parts - 7 cervical vertebrae are in the neck 1. Sternum - 12 thoracic vertebrae are in the chest region 2. Ribs - 5 lumbar vertebrae are associated with the lower - True ribs (pairs 1-7) back Sacrum (formed by fusion of 5 vertebrae) - False ribs (pairs 8-12) - Coccyx (formed by fusion of 3-5 vertebrae) - Floating ribs (pairs 11-12) 3.Thoracic vertebrae APPENDICULAR SKELETON Appendicular Skeleton Composed of 126 bones Limbs (appendages) Pectoral girdle Pelvic girdle Bones of the Shoulder Girdle Also called pectoral girdle Composed of two bones that attach the upper limb to the axial skeletal 1. Clavicle 2. Scapula  Light, poorly reinforced girdle Sacrum is shorter and less curved Ischial spines are shorter and farther apart; thus, the outlet is larger Allows the upper limb a exceptional flexibility Pubic arch is more rounded because the angle of the pubic arch is greater BONES OF UPPER LIMBS Humerus - Forms the arm BONE OF THE LOWER LIMB - Single bone - Proximal end articulation Femur-thigh bone Head articulates with the glenoid cavity of the scapula - The heaviest, strongest bone in the body - Proximal end articulation Distal end articulation - Head articulates with the acetabulum of the coxal (hip) bone - Trochlea and capitulum articulate with the bones Distal end articulation - Lateral and medial condyles articulate with the tibia in the of the forearm lower leg The forearm has two bones The lower leg has two bones 1. Tibia-shinbone; larger and medially oriented 1. Ulna-medial bone in anatomical position Proximal end articulation - Proximal end articulation - Medial and lateral condyles articulate with the femur to form - Coronoid process and olecranon articulate with the knee joint Distal end articulation the humerus - Medial malleolus forms the inner part of the ankle 2. Radius-lateral bone in anatomical position - Proximal end articulation 2. Fibula-thin and sticklike; lateral to the tibia - Has no role in forming the knee joint - Head articulates with the capitulum of the - Distal end articulation humerus Lateral malleolus forms the outer part of the ankle Foot Hand Tarsals-7 bones Carpals-wrist bones Two largest tarsals are the: - 8 bones arranged in two rows of 4 bones in each - Calcaneus (heel bone) - Talus hand Metatarsals-5 bones form the sole of the foot Metacarpals-palm bones Phalanges-14 bones form the toes - 5 per hand Arches of the feet Phalanges-fingers and thumb - Bones of the foot are arranged to form three strong arches - 14 phalanges in each hand - Two longitudinal - One transverse - In each finger, there are 3 bones - In the thumb, there are only 2 bones Joints Joints are articulations - Occur where two or more bones meet BONES OF THE PELVIC GIRDLE Functions of joints - Hold bones together securely Formed by two coxal (ossa coxae) bones - Allow for mobility Composed of three pairs of fused bones Two ways joints are classified 1. Ilium -Functionally 2. Ischium - Structurally 3. Pubis Pelvic girdle = two coxal bones, sacrum Functional joint classifications Pelvis = two coxal bones, sacrum, coccyx Synarthroses - Immovable joints The total weight of the upper body rests on the pelvis Amphiarthroses Pelvis protects several organs - Slightly movable joints - Reproductive organs Diarthroses - Urinary bladder - Freely movable joints - Part of the large intestine Structural joint classifications Fibrous joints The female’s pelvis - Generally immovable Inlet is larger and more circular Cartilaginous joints Shallower, on the whole, and the bones are lighter and thinner - Immovable or slightly movable Ilia flare more laterally Synovial joints  - Freely movable Earliest “flat bones” of the fetal skull are fibrous Fibrous joints membranes - Bones are united by fibrous tissue As fetus grows, all bone models are converted to bone Types Sutures - Immobile Syndesmoses - Allow more movement than sutures but still immobile - Found on the distal ends of tibia and fibula Gomphoses - Immobile - Found where the teeth meet the facial bones Cartilaginous joints - Bones are connected by fibrocartilage Types Synchrondrosis - Immobile Fetal skull - Found in epiphyseal plates of growing long bones Fontanels are fibrous membranes connecting the Symphysis - Slightly movable cranial bones - Found in the pubic symphysis, intervertebral joints - Known as “soft spots” - Allow skull compression during birth Synovial joints - Articulating bones are separated by a joint cavity - Allow the brain to grow during later pregnancy - Synovial fluid is found in the joint cavity and infancy Four distinguishing features of synovial joints - Usually ossify by 2 years of age 1. Articular cartilage 2. Articular capsule 3. Joint cavity 4. Reinforcing ligaments Synovial joints (continued) Bursae-flattened fibrous sacs - Lines with synovial membranes - Filled with synovial fluid - Not actually part of the joint Tendon sheath - Elongated bursa that wraps around a tendon Types of synovial joints based on shape Plane joint Hinge joint Pivot joint Condylar joint Saddle joint Ball-and-socket joint Growth of cranium after birth is related to brain growth - Increase in size of the facial skeleton follows tooth development and enlargement of the respiratory passageways Size of cranium in relationship to body - 2 years old-skull is three-fourths the size of adult DEVELOPMENT ASPECTS OF THE SKELETON skull Birth to adulthood - 8 or 9 years old-skull is near adult in size and First “long bones” of a fetus are hyaline cartilage proportion  - Between ages 6 and 11, the face grows out from the skull Skeletal changes At birth, the head and trunk are proportionately much longer than the lower limbs During puberty: - Female pelvis broadens - Entire male skeleton becomes more robust By the end of adolescence: - Epiphyseal plates become fully ossified Older adults Osteoporosis - Bone-thinning disease afflicting: - 50 percent of women over age 65 - 20 percent of men over age 70 Disease makes bones fragile, and bones can easily fracture Vertebral collapse results in kyphosis (also known as “dowager’s hump”) Estrogen aids in health and normal density of a female skeleton