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Chapter 8 - Appendicular Skeleton

Chapter 8 - Appendicular Skeleton - KIN 216 Applied Human...

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Unformatted text preview: KIN 216 Applied Human Anatomy Chapter 8 Appendicular Skeleton Limb bones and girdles girdle: attaches upper limbs to Pectoral trunk Pelvic girdle: attaches lower limbs to trunk Attached to axial skeleton Each limb is composed of 3 basic segments: Hand, forearm, arm: upper limb Foot, leg, thigh: lower limb Pectoral Girdle Clavicle and scapula (pair; shoulders) Attaches upper limb to trunk and provides muscle attachments Allows mobility Only the clavicle attaches (not scapula), allowing scapula to move freely (arm moves) Shallow socket (glenoid cavity) at shoulder joint good for flexibility, bad for stability Clavicle(s) and Scapula(e) Clavicle (collarbone) S-shaped, horizontally oriented, anterior Sternal end attaches to manubrium; acromial end attaches to scapula Provide muscle attachments, act as braces for arms, and transmit force from upper arms to axial skeleton Shoulder blades dorsal side of rib cage, between Triangle-shaped, ribs 2-7 Each has 3 borders: superior, medial, lateral Each has 3 angles: superior, inferior, lateral Acromion = "apex of shoulder" articulates with acromial end of clavicle Upper Limb 30 bones each side (60 total) Arm (brachium) upper limb Humerus Head (largest and longest bone) fits in glenoid cavity 2 condyles at distal end Trochlea (medial articulates with ulna) Capitulum (lateral articulates with radius) Olecranon fossa posterior side, superior to trochlea Upper Limb (2) Forearm Radius and ulna articulate with humerus (proximal) and wrist bones (distal) AND with each other at radioulnar joints (proximal and distal) Interosseous membrane Ulna Slightly longer than radius Main bone forming elbow joint with humerus Olecranon process Head (articulates with radius distally) Upper Limb (3) Forearm Radius Thin (cont'd) at proximal end, wide at distal end Head is round, articulates with humerus Hand Includes carpals (carpus = wrist), metacarpals (palm), and phalanges (fingers) Carpus Proximal region of hand, distal to wrist joint 8 short bones connected by ligaments (2 rows of 4 bones) Proximal row, lateral to medial: scaphoid, lunate, triquetral, pisiform Distal row, lateral to medial: trapezium, trapezoid, capitate, hamate Upper Limb (4) Hand 5 (cont'd) (meta = beyond) Metacarpus radiate from wrist, form palm Numbered 1-5, #1 is thumb side Heads articulate with phalanges, form knuckles Phalanges Digits (fingers) also numbered 1-5, #1 is thumb (pollex) Each digit (EXCEPT thumb) has 3 phalanges (proximal, middle, distal); no middle phalanx for thumb Pelvic Girdle Attaches lower limbs to spine and supports visceral pelvic organs Strongly attached to axial skeleton Acetabulum is deep, allowing less movement in lower limbs than upper Paired hip bones (coxal or os coxa), which unite with each other and sacrum are large, 3 fused bones Ilium, ischium, pubis are separate in childhood Pelvic Girdle (2) Hip bones (cont'd) Ilium Ala = wing Iliac crest = thickened superior margin of ala Anterior superior iliac spine (ASIS) Ischium Ischial tuberosity where you sit Pubis V-shaped, has rami Obturator foramen hole between pubis and ischium Pubic symphysis fibrocartilage cartilage Lower Limb Carry body weight; thicker and stronger than corresponding upper limb bones 3 segments: thigh, leg, foot Thigh Bone = femur Head = ball-like shape with central pit called fovea capitis Greater and lesser trochanters Patella = sesamoid bone enclosed in tendon running from quadriceps muscles to tibia Lower Limb (2) Leg Refers to area between knee and ankle Bones are tibia and fibula Articulate with each other proximally and distally Interosseous membrane Tibia = bigger and medial to fibula, articulates with femur at knee joint and talus at ankle joint Medial and lateral condyles articulate with femur Tibial tuberosity = where patellar ligament attaches Medial malleolus = medial bulge of ankle Lower Limb (3) Leg (cont'd) Fibula = smaller, lateral to tibia, does not contribute to knee and helps stabilize ankle Head = superior end Lateral malleolus = inferior end (forms lateral bulge of ankle), articulates with talus Not weight bearing, but many muscles attach Lower Limb (4) Foot 2 important functions Supports body weight Acts as level to help propel body Includes bones of tarsus, metatarsus, and phalanges Tarsus Posterior half of foot 7 tarsals (bones): talus, calcaneus, cuboid, navicular, and cuneiforms (medial, intermediate, and lateral) Lower Limb (5) Foot (cont'd) Metatarsus Similar to metacarpals, numbered 1-5 beginning on medial side structure to hand, but bones are Phalanges Similar smaller 3 phalanges for each digit except hallux (2) Disorders of Appendicular Skeleton Most disorders are fractures (chpt. 6) Birth defects Hip dysplasia Acetabulum fails to completely form OR ligaments of hip are loose causes head of femur to slip out of socket Clubfoot Soles of feet turn medially and toes point inferiorly Can be genetic or abnormal positioning Development of Appendicular Skeleton Upper-lower age body ratio changes with Lower body = distance from top of pelvic girdle to ground Upper body = difference between lower body height and total height Birth: UL ratio is 1.7:1; after this, lower limbs grow faster than the trunk Age 10: UL ratio is 1:1 Female pelvis broadens during puberty ...
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