The Pectoral Girdle and Upper Limbs

Function of the Upper Extremities

The upper extremities primary function is to facilitate movement for daily activities.

The pectoral girdle (or shoulder girdle) attaches the bones of the upper limb to the axial skeleton.

Each pectoral girdle consists of two bones:

the clavicle

the scapula.

The upper extremity includes the bones of the arm, wrist, and hand.

Bones of the Pectoral Girdle

Clavicle

Also called the “collar bone”. Long slender bone with a double curve. Each clavicle attaches to the:

a. manubrium at the sternal end

b. Flat, anterior projection of the scapula at the acromion end

c. It acts as a brace to hold the arm away from the thorax and it helps to prevent shoulder dislocation.

Scapula

Also called the “shoulder blade”. Large, triangular, flat bone located in the lateral portion of the upper back. Has 3 borders:

1. superior

2. lateral (axillary)

3. medial (vertebral)

The glenoid fossa is the shallow socket that holds the head of the arm bone.

The scapula has two important projections:

1. acromion process – the flat, large end that connects with the clavicle.

2. coracoid process – a smaller, beak-like structure that anchors some of the muscles of the arm.

Bones of the Upper Extremities

There are 30 separate bones that make up the skeleton of the upper limb.

They are composed of:

The arm (1 bone)

The forearm (2 bones)

The hand (27 bones)

Humerus

The longest and largest bone of the upper extremity.

It articulates:

proximally with the scapula (fits into the glenoid fossa)

distally with the radius and ulna.

The head at the proximal end fits into the glenoid fossa

Two epicondyles at the distal end that articulate with the forearm bones:

Medial epicondyle

Lateral epicondyle

Ulna

The medial bone of the forearm.

Located on the little finger side of the elbow. Articulates with humerus to form the elbow.

a. At the proximal end, two projections form an indented area that holds the humerus bone.

b. They are coronoid process and the olecranon process.

Radius

The lateral bone of the forearm. Located on the thumb side of the forearm.

The 2 bones are connected along their entire lengths by an flexible interosseous membrane

The Hand

The skeleton of the hand consists of: carpals, metacarpals, and phalanges.

Carpals

8 small bones that make up “the wrist”.a. Carpals are bound together by ligaments.b. Arranged in two rows of four bones.

Metacarpals

5 bones that make up the palm of the hand.a. They are number “1” through “5” starting with the thumb to the pinky.b. Heads of the metacarpals are commonly called knuckles.

Phalanges

14 bones that make up the fingers in each hand.a. Each phalange has 3 bones each (proximal, medial, and distal) with the exception of the

thumb.b. Thumb has only two phalanges.

Label the bones of the hand: