chapter 8

Bones of the Appendicular Skeleton

• Pectoral Girdle: Composed of 4 bones total - 2 clavicles and 2 scapulae.

  • Functions to attach upper limbs to the body.

• Pelvic Girdle: Composed of 2 coxal bones (hip bones).

  • Articulates with the sacrum to form a ring.

Distribution of Bones

• Upper and Lower Limbs: Each contains 60 bones.

  • Phalanges (fingers and toes) total 28.

  • Metacarpals (hands) and Metatarsals (feet) total 10 each.

  • Carpals (wrist) total 16; Tarsals (ankle) total 14.

Pectoral Girdle Details

• Clavicle:

  • S-shaped bone.

  • Medial (sternal) end articulates with the sternum (sternoclavicular joint).

  • Lateral (acromial) end articulates with the scapula (acromioclavicular joint).

• Scapula: Flat triangular bone on the posterior thorax.

  • Contains:

    • Acromion: High point of shoulder.

    • Coracoid Process: Muscle attachment site.

    • Glenoid Cavity: Articulates with the head of the humerus (glenohumeral joint).

Upper Limb Anatomy

• Humerus (30 bones total per upper limb):

  • Proximal features: Head, greater and lesser tubercles.

  • Distal features: Capitulum (articulates with the radius) and trochlea (articulates with the ulna).

• Radius and Ulna: Form the forearm; articulate with the humerus and each other to form the elbow joint.

• Wrist:

  • Composed of 8 carpals divided into proximal (scaphoid, lunate, triquetrum, pisiform) and distal groups (trapezium, trapezoid, capitate, hamate).

Pelvic Girdle Details

• Coxal Bones: Articulate with each other and sacrum.

  • Composed of the ilium, pubis, and ischium.

  • Differences between male and female pelvis:

    • Females have a wider angle (100-120 degrees) for childbirth.

    • Males have a narrower angle (less than 90 degrees).

Lower Limb Anatomy

• Femur: Longest bone, articulates with the acetabulum of the coxal bone.

  • Contains features like the greater and lesser trochanters, neck (common fracture site), and linea aspera.

• Tibia and Fibula:

  • Tibia: Medial bone, supports body weight; articulates with the femur and forms the knee joint.

  • Fibula: Lateral bone, slender; supports the ankle but does not bear weight.

• Tarsus: Composed of 7 tarsal bones (talus, calcaneus, navicular, cuboid, and three cuneiforms).

• Metatarsals and Phalanges: Similar structure to hands, with a total of 14 phalanges per foot (two in the big toe, Hallux).

Foot Structure and Disorders

• Foot Arches:

  • Maintained by ligaments and tendons; include longitudinal and transverse arches.

  • Disorders include flat foot (decreased arch), club foot (increased arch), and bunions (deformity of the big toe).

This summary covers key concepts related to the bones of the pectoral and pelvic girdles, their anatomical significance, and the structure of limbs, including common disorders related to foot structure.