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The Appendicular Skeleton

The Appendicular Skeleton. THE SKELETAL SYSTEM The Appendicular Skeleton. 2 pairs of limbs and 2 girdles Pectoral (shoulder) girdle attaches upper limbs Pelvic (hip) girdle secures lower limbs 3-Segmented limbs Upper = arm Arm Forearm Hand Lower = leg Thigh Leg Foot.

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The Appendicular Skeleton

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  1. The Appendicular Skeleton

  2. THE SKELETAL SYSTEMThe Appendicular Skeleton • 2 pairs of limbs and 2 girdles • Pectoral (shoulder) girdle attaches upper limbs • Pelvic (hip) girdle secures lower limbs • 3-Segmented limbs • Upper = arm • Arm • Forearm • Hand • Lower = leg • Thigh • Leg • Foot

  3. Pectoral Girdle(Shoulder Girdle) • Clavicle – anterior: collar bone • Sternal end attaches to the manubrium medially • Acromial end articulates with the scapula laterally • Scapula – posterior: shoulder blade

  4. Scapulae: triangular, paired, but don’t connect in back (adds thoracic flexibility)

  5. Scapula • Glenoid cavity articulates with the humerus • Acromium articulates with clavicle • Coracoid process projects anteriorly

  6. Upper extremity • Arm or Brachium = upper arm • Between shoulder and elbow (humerus) • Forearm or Antebrachium • Radius & ulna • Hand includes: • Wrist (carpus) • Palm (metacarpus) • Fingers (phalanges)

  7. Arm • Humerus is the only bone • Head of humerus fits into glenoid cavity of scapula • Distal & medially, trochlea articulates with the ulna • Distal & laterally capitulum articulates with the radius • Medial & lateral epicondyles

  8. Right humerus, anterior view

  9. Right humerus, posterior view

  10. Radius is thinner proximally, like a spool of thread, and wide distally; ulna is slightly longer and looks like a monkey wrench (supposedly!) Forearm • 2 bones: articulate with each other proximally and distally • Interosseous membrane between them • Ulna • Olecranon hinges with the humerus forming elbow • Styloid process distally • Radius • Contributes to wrist joint • Styloid process anchors a ligament to wrist (thumb side)

  11. Right forearm bones, anterior view

  12. Right forearm bones, posterior view

  13. Left forearm In the anatomical position, the radius is lateral (thumb side); with pronation the palm faces posteriorly and the bones cross Prone: body lying face down Suppine: body lying face up Anatomical position prone (you can remember prone if you think about how you would fall forward onto your face if you passed out) pronation moves the forearm into the prone position and supination moves it back to the anatomical position

  14. Proximal and distal joints of the forearm proximal ulna

  15. Hand • Proximal is “wrist” – 8 carpal bones • Palm of hand - 5 metacarpals • Fingers (or digits) consist of miniature long bones called phalanges: thumb (“pollex”) has 2; fingers have 3: proximal, middle, distal Right hand, 2 views:

  16. Pelvic Girdle (Hip Girdle) • Strongly attached to axial skeleton (sacrum) • Deep sockets • More stable than pectoral (shoulder) girdle • Less freedom of movement • Made up of the paired hip bones • “Bony pelvis” is basin-like structure: hip bones plus the axial sacrum and coccyx

  17. Hip bone (os coxae): 3 separate bones in childhood which fuse • Ilium • Ischium • Pubis

  18. Ilium ilium • Iliac crest • Anterior superior iliac spine • Greater sciatic notch • Forms part of “acetabulum” (hip socket) which receives ball-shaped head of femur ilium

  19. Ischium • Body • Ramus • Ischial spine • Ischial tuberosity • Part of socket ischium ischium

  20. Pubis • Joins medially in pubic symphysis • Forms “obturator foramen” (large hole) with ischium • Part of socket pubis pubis

  21. Hip bones with labels

  22. False (greater) and true (lesser) pelvis Ligaments

  23. Pelvis and childbearing • Male/female differences • Large & heavy vs light & delicate • Heart shaped pelvic inlet vs oval • Narrow deep true pelvis vs wide & shallow • Narrow outlet vs wide • Less than 90 degree pubic arch vs more than 90 degree • Birth canal changes shape as baby descends: head turns ¼ • Higher: pelvic inlet (brim) - side to side largest • Lower: pelvic outlet - largest in AP direction

  24. Lower limb • Thigh: femur • Leg (lower leg) • Tibia • Fibula • Foot

  25. Thigh • Femur is largest, longest and strongest bone in the body • Head fits in socket (acetabulum) of pelvis • Neck is weakest • Greater trochanter • Distal: lateral & medial condyles and epicondyles • Patella: sesmoid bone

  26. Right femur, anterior view

  27. Right femur, posterior view

  28. Leg • Tibia: shin bone • Medial and lateral condyles • Tibial tuberosity • Distal medial malleolus (medial ankle) • Fibula • Distal lateral malleolus (lateral ankle) • Interosseous membrane

  29. Right lower leg, anterior view

  30. Foot • Tarsus: 7 tarsal bones • Talus: articulates with tibia and fibula anteriorly and calcaneus posteriorly • Calcaneus: heel bone • Smaller cuboid, navicular, and 3 cunieforms (medial, intermediate and lateral) • 5 metatarsals • 14 phalanges • Great toe is hallux

  31. Right foot, superior (dorsal) view and inferior (plantar) view

  32. Right foot, lateral and medial views

  33. Arches

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