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THE SKELETAL SYSTEM

THE SKELETAL SYSTEM. CHAPTER 5B. I. Axial Skeleton. A. Forms longitudinal axis of body B. Can be ÷ i /t 3 parts: 1. skull 2. vertebral column 3. bony thorax C. Cranium 1. composed of 8 lg. flat bones *frontal – form forehead *parietal bones – paired bones that meet in

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THE SKELETAL SYSTEM

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  1. THE SKELETAL SYSTEM CHAPTER 5B

  2. I. Axial Skeleton A. Forms longitudinal axis of body B. Can be ÷ i/t 3 parts: 1. skull 2. vertebral column 3. bony thorax C. Cranium 1. composed of 8 lg. flat bones *frontal – form forehead *parietal bones – paired bones that meet in midline of skull @ sagittal suture *temporal bones – inferior to parietal; contain mastoid process wh/ is a rough projection that provides neck muscle attachment

  3. *occipital bone – joins parietal bones @ the lambdoid suture; has lg. opening in base called the foramen magnum *sphenoid bone – butterfly shaped in floor of cranial cavity *ethmoid bone – irregularly shaped; forms roof of nasal cavity; has holey areas called the cribriform plates that allow nerve fibers from olfactory receptors (nose) to reach the brain

  4. 2. facial bones a. maxillae- *also called maxillary bones *2 fuse t/g to form upper jaw b. zygomatic bones *referred to as the cheekbones c. vomer bone *forms most of nasal septum 3. hyoid bone a. the only bone that does not articulate directly w/ any other bone b. suspended above the larynx c. anchored by ligaments

  5. 4. fetal skull a. has fibrous regions that aren’t yet converted to bone b. these fibrous membranes that connect the cranial bones fontanels ”soft spots” c. fontanels allow skull to be compressed during birth d. fontanels allow infant’s brain to grow

  6. D. Vertebral Column (spine) page 149 1. consists of separate bones vertebrae 2. types of vertebrae: (pg.149) a. cervical vertebrae *7 vertebrae of the neck *1st 2 vertebrae (atlas, axis) are different from others due to functions b. thoracic vertebrae *12 vertebrae of upper back region c. lumbar vertebrae *5 vertebrae of the lower back region *where most stress on vert. col. Occurs *sturdiest of the vertebrae (NOTE: Remember common meal times for #s of vertebrae)

  7. d. sacrum (pg. 152) *fusion of 5 vertebrae e. coccyx *fusion of 3-5 tiny, irregularly shaped vertebrae *”tailbone”

  8. 3. curvatures of the spine a. spine has an S-shaped structure that helps prevent shock to the head when we walk/run b. primary curvatures *curves in the thoracic & sacral regions *present @ birth c. secondary curvatures *curves in the cervical & lumbar regions *develops when walking begins d. several types of abnormal curvatures *illus. pg. 150 *may be congenital, due to disease, injury, poor posture, etc.

  9. E. bony thorax 1. sternum (breastbone) *fusion of 3 bones: manubrium body xiphoid process *attached to 1st 7 pr. Ribs 2. ribs (pg. 153) *12 pair *true ribs – 1st 7 pr.; attach directly to sternum by costal cartilage *false ribs – next 5 pr.; attach to sternum indirectly or not at all *floating ribs – last 2 pr. of false ribs; no sternal attachment

  10. II. Appendicular skeleton A. 126 bones of limbs, pectoral and pelvic girdles B. Pectoral Girdle 1. shoulder girdle 2. consists of 2 bones: clavicle, scapula 3. clavicle a. also called the collarbone b. connects sternum to scapula c. helps form shoulder joint; acts as brace to hold arm a/w from thorax; helps prevent shoulder dislocation

  11. 4. scapulae a. also called the shoulder blades b. triangular shaped c. connects to clavicle; anchors some of arm muscles C. upper limb 1. humerus a. upper arm bone b. proximal end rounded head  fits i/t glenoid cavity of scapula c. distal end  2 bony projections  > and < tubercles (Pg. 156) (sites of muscle attachments)

  12. 2. forearm a. formed by 2 bones b. radius *lateral bone *on thumb side of forearm *able to rotate and cross over ulna & ends up medial to ulna when palm faces back c. ulna *medial bone *on little finger side of forearm 3. hand a. carpal bones – 8 bones arranged in two irregular rows of 4 (wrist) b. metacarpals – 5 bones in the palm of the hand; the heads form the knuckles c. phalanges – 14 bones in ea. hand; 3 in ea. finger, 2 in ea. thumb

  13. D. Pelvic Girdle 1. formed by 2 coxal bones (hip bones) 2. coxal bones ea. is a fusion of 3 bones: a. ilium – lg. flaring bone that forms most of the hip bone; connects posteriorly w/ sacrum b. ischium – forms the most inferior part; the “sit-down” bone c. pubis (pubic bone) – most anterior part; pubis bones fuse t/g pubic symphysis 3. female vs. male differences (illus.pg.158, listed pg.159) a. ischial spines are shorter & farther apart outlet larger b. pubic arch is > rounded due to > angle of pubic arch

  14. E. lower limb 1. femur a. only bone in the thigh b. heaviest, strongest bone in the body c. proximal end *has a ball-like head wh/ articulates w/ the acetabulum *neck is a common fracture, esp. w/ older persons d. distal end *articulates w/ tibia *anteriorly has the patellar surface  forms a joint w/ patella (knee cap) e. slants medially as it joins w/ leg bones knees in line w/ body’s center of gravity

  15. 2. lower leg a. made up of 2 bones: tibia, fibula b. 2 bones are connected by an interosseous membrane c. tibia *”shinbone” *larger, more medial *proximal end articulates w/ femur  knee joint *distally forms the inner bulge of the ankle d. fibula *thin, sticklike *no part in forming knee joint; does form the outer part of the ankle

  16. 3. foot a. 2 functions: *supports body weight *serves as a lever that allows us to propel us forward when we walk/run b. tarsus *forms posterior half of foot *composed of 7 tarsal bones *2 largest: -calcaneus: heelbone -talus: b/t tibia & calcaneus c. metatarsals: 5 form the sole d. phalanges: 14 form the toes

  17. III. joints A. also called articulations B. where 2 or > bones meet C. 2 functions: 1. hold bones t/g (ligaments) 2. gives rigid skeleton mobility D. classified 2 ways: 1. functionally 2. structurally E. functional classifications 1. synarthroses – immovable joints 2. amphiarthroses – slightly movable joints 3. diarthroses – freely movable joints

  18. F. structural classifications (pg. 164) 1. fibrous joints bones are united by fibrous tissue 2. cartilaginous joints bone ends are connected by cartilage 3. synovial joints (pg. 165) *articulating bone ends are separated by a joint cavity containing synovial fluid (all joints of the limbs) *types are based on shape

  19. G. shapes of synovial joints 1. plane joints *short slipping or gliding mmt. *no rotation *ex: intercarpal joints 2. hinge joint *cylindrical end fits i/t a trough-shaped surface *angular mmt. in 1 plane *ex: elbow joint, ankle joint 3. pivot joints *rounded end fits i/t a sleeve/ring *rotating mmt. in 1 direction *proximal radioulnar joint, joint b/t atlas & axis

  20. 4. condyloid joint *egg-shaped surface fits i/t oval concavity *mmt. is side to side & back and forth *no rotation *ex: knuckles 5. saddle joint *ea. articular surface has both convex & concave areas *same mmt. As condyloid joints *ex: carpometacarpal joints 6. ball-and-socket joint *spherical head fits i/t rounded socket *mmt. occurs in all axes *ex: shoulder & hip

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