The Skeletal System: The Appendicular Skeleton

I. Introduction A. The appendicular skeleton includes the bones of the upper and lower extremities and the shoulder and hip girdles.

I. Introduction B. The appendicular skeleton functions primarily to facilitate movement.

II. Pectoral (Shoulder) Girdle A.

The pectoral girdle attaches the bones of the upper limbs to the axial skeleton.

II. Pectoral (Shoulder) Girdle 1. The clavicle or collar bone lies horizontally in the superior and anterior part of the thorax and articulates with the sternum and the scapula.

II. Pectoral Girdle Continue The clavicle, one of the most frequently broken bones in the body

II. Pectoral Girdle Continue 2. The scapula or shoulder blade articulates with the clavicle and the humerus.

II. Pectoral Girdle Continue The scapulae is held in place posteriorly only by complex shoulder and back musculature.

III. Upper Limb A.

Each upper limb consists of 30 bones including the humerus, ulna, radius, carpals, metacarpals, and phalanges.

III. Upper Limb 1. The humerus is the longest and largest bone of the upper limb.

III. Upper Limb It articulates proximally with the scapula at the

glenohumeral joint

distally at the elbow with both the radius and ulna.

, and

III. Upper Limb Continue 2. The ulna is located on the

medial

aspect of the foramen.

III. Upper Limb Continue 3. The radius is located on the lateral aspect

(thumb side)

of the foramen.

III. Upper Limb Continue  Falling on an outstretched arm may create a Colle’s fracture, a fracture near the distal end.

Upper Limb Continue The radius and ulna articulate with the humerus at the elbow joint, with each other, and with three carpal bones.

Upper Limb Continue 4. Carpals, Metacarpal, Phalanges

Upper Limb Continue The eight carpal bones, bound together by ligaments, comprise the wrist.

Upper Limb Continue  Because of the scant blood supply to the

scaphoid

, scaphoid fractures may be very slow to heal.

III. Upper Limb Continue Five metacarpal bones are contained in the palm of each hand.

III. Upper Limb Continue Each hand contains 14 phalnges, three in each finger and two in in each thumb.

IV. Pelvic Girdle A.

The pelvic (hip) girdle consists of two hipbones (coxal bones) on which the weight of the body is carried.

IV. Pelvic Girdle  1.

2.

3.

Each hipbone is composed of three separate bones at birth: Ilium pubis ischium.

IV. Pelvic Girdle  These bones eventually fuse at a depression called the

acetabulum

, which forms the socket for the hip joint.

IV. Pelvic Girdle  The ilium is the largest and articulates (fuses) with the ischium and pubis.

IV. Pelvic Girdle  The ischium is the inferior, posterior portion of the hip bone.

IV. Pelvic Girdle  The pubis is the anterior and inferior part of the hip bone.

IV. Pelvic Girdle Continue B. True or False Pelves 1. Together with the sacrum and coccyx, the two hipbones form the pelvis.

IV. Pelvic Girdle Continue 2. The greater (false) and lesser (true) pelvis are anatomicaly separated by a plane at the pelvic brim.

V. Comparison of Male and Female  Female and male pelvic girdles differences are primarily related to the need for a larger outlet in females to facilitate childbirth.

V. Comparison of Female and Male Pelves  Male bones are larger and heavier than those of the female

V. Comparison of Female and Male Pelves  Male’s joint surfaces also tend to be larger.

V. Comparison of Female and Male Pelves  Muscle attachment points are more well defined in the bones of a male than of a female due to the larger size of the muscles in males.

V. Comparison of Female and Male Pelves  Iliac bones of male more vertical

V. Comparison of Female and Male Pelves  Pelvic brim in male is heart shaped due to prominence of the sacral promontary

V. Comparison of Female and Male Pelves  Pelvic brim more oval in female

V. Comparison of Female and Male Pelves  Pubic arch in male is under 90 degrees

V. Comparison of Female and Male Pelves  Pubic arch in females over 90 degrees

VI. Comparison of Pectoral and Pelvic Girdles 1.

The pectoral girdle does not directly articulate with the vertebral column; the pelvic girdle does.

VI. Comparison of Pectoral and Pelvic Girdles 2. The pectoral girdle sockets are shallow and maximize movement

VI. Comparison of Pectoral and Pelvic Girdles 3. Sockets of the pelvic girdle are deeper and allow less movement.

VI. Comparison of Pectoral and Pelvic Girdles 4. The structure of the pectoral girdle offers more movement than strength

VI. Comparison of Pectoral and Pelvic Girdles 5. The pelvic girdle, more strength than movement.

VII. Lower Limb A.

Each lower extremity is composed of 30 bones, including the femur, tibia, fibula, tarsals, metatarsals, and phalanges.

Femur • The femur or thighbone is the largest, heaviest, and strongest bone of the body.

Femur • It articulates with the hip bone and the tibia.

Patella  The patella or kneecap is a sesamoid bone located anterior to the knee joint

Patella • Protects the knee joint

Patellofemoral stress syndrome • Common knee problem in runners

Patellofemoral stress syndrome • During normal flexion and extension of the knee, the patella tracks up and down in the patellar groove of the femur

Patellofemoral stress syndrome  In this syndrome the patella also tracks laterally, increasing the pressure on the cartilage coating the underside of the patella.

Tibia  The tibia or shinbone is the larger, medial, weight-bearing bone of the leg.

Fibula  The fibula is parallel and lateral to the tibia.

Tarsals  Seven tarsal bones constitute the ankle

Metatarsals  Five metatarsal bones are contained in the foot.

Phalanges  Fourteen bones in each foot.

Arches of the foot • The bones of the foot are arranged in two nonrigid arches that enable the foot to support the weight of the body

Arches of the foot  Provide an ideal distribution of body weight over the hard and soft tissues

Arches of the foot  Provide leverage while walking.

Arches of the foot  The longitudinal arch has a medial and lateral component.

Arches of the foot  The transverse arch is perpendicular to these arches.

VII. Lower Limb Continue 2. As a person ages, they tend to get flattening of the longitudinal arches, causing the foot to elongate.

Hip Fractures  A break in the bones associated with the hip joint.

Hip Fractures  Often require surgical treatment

Hallux  Called a bunion

Hallux  The proximal phalanx of the great toe deviates laterally

Hallux  The first metatarsal deviates medially.