Biology 141

1. Biology 141 The Appendicular Skeleton Chapter 8

2. INTRODUCTION • The appendicular skeleton includes • 2 Pectoral girdles • Pelvic girdle • Upper limbs • Lower limbs • The appendicular skeleton functions primarily to facilitate movement.

3. Pectoral Girdle • Pectoral Girdle: scapula + clavical • Clavical – “S” shape, • articulates with manubrium of the sternum medially • Sternoclavicular joint • Articulates with the scapula laterally. • Acromioclavicular joint

4. Clavicle • collar bone • one of the most frequently broken bones in the body • transmits mechanical force from the upper limb to the trunk.

5. Clavicle • Ligaments attached to clavicle stabilize its position.

6. Pectoral Girdle Scapula – triangular, flat bone of the shoulder. • Glenoid cavity – socket for humerus • Scapular spine – ridge on posterior side dividing the superior (supraspinous fossa) from the inferior (infraspinous fossa)

7. Scapula Scapula • Subscapular fossa – anterior concave surface • Scapular notch – on the superior margin, just medial to the coracoid process

8. Pectoral Girdle • 3 margins • medial border: vertebral margin • lateral border: axillary margin • superior border: superior margin • Lateral processes • acromion process: attachment of clavical posteriorly • coracoid process: anterior, smaller process, bent laterally

9. Posterior Surface of Scapula

10. UPPER EXTREMITY • Each upper limb consists of 30 bones • Humerus - arm • Ulna - forearm • Radius - forearm • Carpals - wrist • Metacarpals - palm • Phalanges - fingers

11. Upper Extremity • Joints • shoulder (glenohumeral), • Elbow • Wrist • Metacarpophalangeal • Interphalangeal

12. Humerus • The humerus is the longest and largest bone of the upper limb. • Proximal end: articulates with the scapula • Distal end: articulates with both the radius and ulna. Proximal Humerus • Head & anatomical neck • Greater & lesser tubercles for muscle attachments • Intertubercular sulcus • Body - shaft • Deltoid tuberosity – V-shaped area

13. Humerus Distal humerus • Forms elbow joint with ulna and radius • Capitulum • articulates with head of radius • Trochlea • articulation with ulna • Olecranon fossa • posterior depression for olecranon process of ulna • Medial & lateral epicondyles • attachment of forearm muscles

14. Radius Radius (on thumb side) • Proximal • head articulates with capitulum of humerus • radial notch of ulna • tuberosity for muscle attachment • Distal • forms wrist joint with scaphoid, lunate & triquetrum • Lateral styloid process

15. Ulna Ulna (on little finger side) • Proximal • trochlear notch articulates withhumerus • olecranon process forms point of elbow • Distal • styloid process • Head • separated from wrist joint by fibrocartilage disc

16. Ulna & Radius

17. Ulna and Radius

18. Carpals, Metacarpal, and Phalanges • 8 carpal bones - wrist • 5 metacarpal bones - palm • 14 phalanges (3 in each finger, two in thumb).

19. 8 Carpal Bones (wrist) • Proximal row – • lateral to medial • scaphoid - boat shaped • lunate - moon shaped • triquetrum - 3 corners • pisiform - pea shaped • Distal row - lateral to medial • trapezium - four sided • trapezoid - four sided • capitate - large head • hamate - hooked process

20. Metacarpals • Metacarpals • 5 total • #1 proximal to thumb • Consists of • Base • Shaft • head • knuckles are the metacarpophalangeal joints

21. Phalanges • Phalanges • 14 total: each is called phalanx • Each finger consists of 3 bones • Proximal • Middle • distal on each finger • Thumb only has only proximal and distal bones • Each bone consists of • Base • Shaft • Head

22. Pelvis • Pelvis includes • Os coxae • Sacrum • coccyx • Subdivisions: • The greater (false) pelvis • The lesser (true) pelvis

23. PELVIC GIRDLE • os coxae bones • provides a strong and stable support the weight of the body • Each os coxa bone is composed of three separate bones at birth: • Ilium • Pubis • ischium.

24. Os Coxa • Os coxa; ossification is complete in the adult and the suture lines are not visible. • front arch – os coax join at the symphysis pubis • fuse at a depression (acetabulum), which forms the socket for the hip joint.

25. Pelvic Girdle • Articulate with sacrum and coccyx • Sacroiliac joint – between sacrum and ilium • Acetabulum – circular depression for femur • Iliac crest – from the anterior superior spine to the posterior superior spine

26. Os Coxa • Ischium processes • ischial spine • ischial tuberosity – one sits on this. • lesser sciatic notch – inferior to the ischial spine • greater ischial notch – superior to the ischial spine • obturator foramen – opening surrounded by the ishium and pubis

27. Pelvimetry, the measurement of the size of the inlet and the outlet of the birth canal, is important during pregnancy Pelvic brim separates false from true pelvis false pelvis holds only abdominal organs Inlet – superior Outlet - inferior Pelvic axis - path of babies head Pelvis

28. Female vs. Male • Pelvic outlet is wider in females. • Greater sciatic notch is rounder in females, shifting the coccyx to widen the pelvic outlet.

29. Female vs. Male • In females, the false pelvis is wider and more lateral, widening the pelvic inlet. • In females, The pubic arch is greater than 90%.

30. Pelvis • Male skeleton • larger and heavier • larger articular surfaces • larger muscle attachments • Female pelvis • wider & shallower • larger pelvic inlet & outlet • more space in true pelvis • pubic arch >90 degrees

31. COMPARISON OF PECTORAL AND PELVIC GIRDLES • The pectoral girdle does not directly articulate with the vertebral column; the pelvic girdle does. • The pectoral girdle sockets are shallow and maximize movement; those of the pelvic girdle are deeper and allow less movement. • The structure of the pectoral girdle offers more movement than strength; the pelvic girdle, more strength than movement.

32. LOWER LIMB (EXTREMITY) • Each lower extremity is composed of 30 bones • Femur -leg • Tibia-lower leg • Fibula-lower leg • Tarsals-ankle • Metatarsals -arch • phalanges -toes

33. Femur • The femur or thighbone is the largest, heaviest, and strongest bone of the body. • articulates with the pelvis and the tibia. • head articulates with acetabulum (attached by ligament of head of femur) • medial & lateral condyles articulate with tibia

34. Femur • Head of the femur • is the obvious rounded projection. • Neck of the femur • is the well-defined narrow region next to the head of the femur. • Greater trochanter of the femur • is the large, roughened area lateral to the head where a muscle attaches (gluteus medius). • Lesser trochanter of the femur • is a much smaller projection distal to the head on the medial side of the bone.  It is also a point of muscle

35. Femur • Medial condyle of the femur • Head-side of bone • rounded, smooth condyle where the femur articulates with the tibia. • Lateral condyle of the femur - is on the greater trochanter side of the bone.

36. Patella • triangular sesamoid bone • increases leverage of quadriceps femoris tendon to maintain the position of the tendon when the knee is bent.

37. Tibia • The tibia or shinbone is the larger, medial, weight-bearing bone of the leg. • Tibial tuberosity of the tibia • prominent, anterior, roughened bump just distal to the knee joint.  • The Quadriceps femoris muscle attaches here. • Medial malleolus of the tibia • the projection on the distal end of the tibia.  Medial bony projection at the ankle joint.

38. Tibia • Medial condyle of the tibia • slight depressions on the flat proximal surface of the tibia where the femur's condyles articulate. • The medial one is on the same side as the distal projection (medial malleolus). • Lateral condyle of the tibia • the lateral depression on the flat proximal surface of the tibia.

39. Fibula • The fibula is parallel and lateral to the tibia • Head of the fibula • proximal end where the fibula attaches to the lateral surface of the tibia.  Note- this end is not involved in the knee joint • Lateral malleolus • distal end, lateral ankle bump.

40. Tibia and Fibula

41. Tarsals, Metatarsals, and Phalanges • 7 tarsal bones (ankle) • share the weight associated with walking • 5 metatarsal bones (foot arch) • Fractures of the metatarsals are common among dancers, especially ballet dancers. • 14 phalanges (toes) • same as that described for the fingers and thumb.

42. Tarsals • Talus • most proximal, articulates with the tibia.  • Calcaneus • largest, most posterior, forms the heel.  The Achilles tendon attaches to this bone • Navicular • medial, boat-shaped bone • Cuboid • cube shaped, lateral to the navicular. • Cuneiforms first, second and third - 3 small stick-like bones. 

43. Metatarsus • Metatarsus • midregion of the foot • 5 metatarsals • #1 is most medial • Each bone consists of • Base • Shaft • Head

44. Phalanges • Phalanges • distal portion of the foot • similar in number and arrangement to the hand • big toe is hallux

45. Arches of the Foot • Function • distribute body weight over foot • yield & spring back when weight is lifted • Longitudinal arches along each side of foot • Transverse arch across midfoot region • navicular, cuneiforms & bases of metatarsals

46. Clinical Problems • Flatfoot • weakened ligaments allow bones of medial arch to drop • Clawfoot • medial arch is too elevated • Hip fracture • 1/2 million/year in US • osteoporosis • arthroplasty

47. DEVELOPMENTAL ANATOMY OF THE SKELETAL SYSTEM Bone forms from mesoderm. • Week 4: skull begins. • Week 5: extremities develop from limb buds. • Week 6: hand plates and foot plates. • Week 8: developed limbs.