CHAPTER 8: Pectoral Girdle and Bones of the Upper Limb

Appendicular Skeleton

Consists of the bones of the limbs and their girdles; includes the pectoral girdle (attaches upper limbs to the trunk) and pelvic girdle (attaches lower limbs to the trunk).

Pectoral Girdle (Shoulder Girdle)

Consists of clavicles (anteriorly) and scapulae (posteriorly); it attaches the upper limbs to the axial skeleton and provides attachment sites for muscles that move the limbs.

Mobility of the Pectoral Girdle

Allows a high degree of movement because the scapulae are not attached to the axial skeleton, and the shoulder joint socket is shallow.

Appendicular Skeleton

Consists of the bones of the limbs and their girdles; it includes the pectoral girdle (attaches the upper limbs to the trunk) and the pelvic girdle (attaches the lower limbs to the trunk).

Pectoral Girdle (Shoulder Girdle)

Consists of clavicles (anteriorly) and scapulae (posteriorly); it attaches the upper limbs to the axial skeleton and provides attachment sites for muscles that move the limbs.

Mobility of Pectoral Girdle

Allows a high degree of movement because the scapulae are not attached to the axial skeleton, and the shoulder joint socket is shallow.

Pelvic Girdle

A structure that attaches the lower limbs to the body trunk.

Clavicle (Collarbone)

S-shaped bone connecting the sternum to the scapula; anchors muscles and acts as a brace to hold the scapulae and arms out laterally.

Sternal End (of Clavicle)

The medial end of the clavicle that articulates with the sternum.

Acromial End (of Clavicle)

The flattened lateral end of the clavicle that articulates with the scapula at the acromion.

Scapula (Shoulder Blade)

A thin, triangular flat bone on the dorsal surface of the rib cage between ribs 2 and 7; it connects the humerus and clavicle.

Superior Border of Scapula:

Shortest and sharpest border

Medial (Vertebral) Border

Runs parallel to the spine.

Lateral (Axillary) Border

Near the armpit; ends superiorly in the glenoid cavity.

Superior Angle

Between the superior and medial borders.

Lateral Angle

Between the superior and lateral borders.

Inferior Angle

Between the medial and lateral borders.

Spine of Scapula

Prominent ridge on the posterior side; actually a crest rather than a true spine.

Acromion

The lateral projection of the scapula that articulates with the clavicle’s acromial end to form the acromioclavicular joint.

Acromioclavicular Joint

The joint formed by articulation between the acromion of the scapula and the acromial end of the clavicle.

Coracoid Process

The anterior projection of the scapula anchors the biceps muscle of the arm.

Suprascapular Notch

An Opening in the superior border of the scapula that allows the passage of nerves.

Glenoid Cavity (Fossa)

Shallow socket on the scapula that articulates with the humerus to form the shoulder joint.

Fossae of the Scapula

Several large depressions named according to location (e.g., subscapular, supraspinous, infraspinous fossae).

How many bones make up each side of the upper limb?

30 bones (60 total for both sides)

Divisions of Upper Limb

Arm, forearm, and hand

Arm Bone

Humerus

Forearm Bones

Radius and ulna.

Hand Bones

8 carpals (wrist), 5 metacarpals (palm), 14 phalanges (fingers).

Humerus

The only bone of the arm, the largest and longest bone of the upper limb.

Humerus Articulations

Superiorly with the glenoid cavity of the scapula; inferiorly with the radius and ulna.

Forearm Skeleton

Formed by two parallel bones — the ulna and radius.

Forearm Articulations

Proximal ends with the humerus and each other; distal ends with each other at the radioulnar joint.

Interosseous Membrane

Connects radius and ulna along their entire length.

Ulna

Medial bone of the forearm; forms the major portion of the elbow joint with the humerus

Olecranon and Coronoid Processes (Ulna)

Grip trochlea of humerus, forming hinge joint

Trochlear Notch (Ulna)

Depression separates the olecranon and coronoid processes.

Radial Notch (Ulna)

Articulates with the head of the radius.

Ulnar Head

Knoblike distal end of the ulna.

Ulnar Styloid Process

Provides attachment for ligaments.

Radius

The lateral bone of the forearm contributes mainly to the wrist joint.

Head (Radius)

Articulates with the capitulum of the humerus and the radial notch of the ulna

Radial Tuberosity

Anchors the biceps muscle.

Ulnar Notch (Radius)

Articulates with the ulna.

Radial Styloid Process

Anchors wrist ligaments.

Colles’ Fracture

A break in the distal end of the radius; common from falling on outstretched hands.

Bones of the Hand

Carpus (wrist), metacarpus (palm), and phalanges (fingers).

Carpus (Wrist)

Made of 8 carpal bones arranged in two rows.

Proximal Row (Carpals, lateral to medial):

Scaphoid, lunate, triquetrum, pisiform.

Distal Row (Carpals, lateral to medial)

Trapezium, trapezoid, capitate, hamate.

Wrist Joint Formation

Formed by the scaphoid, lunate, and triquetrum only.

Carpal Tunnel

A Passageway formed by carpal bones and the flexor retinaculum, where tendons and the median nerve pass into the hand.

Carpal Tunnel Contents

Nine muscle tendons and the median nerve.

Carpal Tunnel Syndrome

A condition caused by inflammation of tendons within the tunnel compressing the median nerve, leading to tingling or numbness.