Human Anatomy - Lecture Notes - Savchuk O.I. 2017

Skeleton of the upper limb

Lecture outline

1. BONES OF THE shoulder girdle.

2. JOINTS OF THE shoulder girdle

3. Structure OF THE humerus.

4. Anatomy of the forearm bones.

5. Joints of the forearm bones

6. Bones of the hand.

The Skeleton OF THE Upper Limb consists of the girdle and the free limb. The girdle consists of two bones: the clavicle and the scapula. The free limb is divided into the following segments: the arm (humerus), the elbow (cubital region), the forearm (radius and ulna), and the hand. The hand is divided into: the wrist (carpus, consisting of 8 bones), the metacarpus, and the Phalanges of the digits.

Bones of the shoulder girdle

The clavicle is an S-shaped curved bone located between the clavicular notch of the Sternum and the acromion of the scapula. It consists of a shaft (body) and two ends: a thickened sternal end and a flattened acromial end. It facilitates Movements of the upper limb by keeping the shoulder joint at an optimal distance from The thoracic cage.

The scapula is a flat, triangular bone. It has superior, inferior, and lateral angles, anterior and posterior surfaces, and medial, lateral, and superior borders. The lateral angle features the glenoid cavity for articulation with the HEAD of the humerus. On the upper part of the posterior surface, There is a spine that projects laterally to end as the acromion. Near the glenoid cavity, along the superior border of the scapula, is the coracoid process. Above the spine lies the supraspinous fossa, and below it is the infraspinous fossa.

Joints of the shoulder girdle

The sternal end of the clavicle articulates with the sternum to form the saddle-shaped sternoclavicular joint. Inside the joint, there is an articular disc, which allows it to function as a ball-and-socket joint. It permits movements of the clavicle around the sagittal axis (elevation and depression), vertical axis (protraction and retraction), and rotation around its own longitudinal axis. The lateral end of the clavicle connects to the acromion of the scapula via a flat, slightly movable joint. Between the coracoid and acromion processes of the scapula, the strong coracoacromial ligament is stretched, which forms an arch over the shoulder joint, preventing the upper limb from being raised above the horizontal line.

Bones of the free upper limb

The humerus is a long bone. It has a shaft and two ends: proximal and distal. The proximal end features the anatomical neck, and below it, the surgical neck (the most common site of fractures). Along the shaft, the radial groove (groove for the radial nerve) runs spirally. The distal end features a condyle for articulation with the forearm bones and two epicondyles: lateral and medial. Above the condyle is the coronoid fossa, and posteriorly is the olecranon fossa. Other features include the trochlea, the capitulum of the humerus, the medial border, the lateral border, the deltoid tuberosity, the crest of the lesser tubercle, the crest of the greater tubercle, the intertubercular sulcus, the lesser tubercle, the greater tubercle, and the groove for the ulnar nerve.

The ulna is located on the medial side of the forearm, on the side of the fifth digit (little finger). It is a long bone that features two processes at its upper (proximal) end: the olecranon and the coronoid process, with the trochlear notch located between them. The lower (distal) end features the head and the styloid process.

Ulnar tuberosity, anterior border of the ulna, interosseous border, articular circumference of the ulna.

The radius is located on the lateral side of the forearm (on the thumb side). It is also a long tubular bone; its upper (proximal) end is represented by the head, below which lies the neck. The lower distal end features the carpal articular surface, the ulnar notch, and the styloid process. The shafts of both forearm bones are triangular, and their sharp borders facing each other are called the interosseous borders. Other features include the lateral surface, anterior surface, posterior surface, radial tuberosity, articular circumference, articular facet of the head, and ulnar notch.

The Carpal Bones are arranged in two rows. The proximal row, starting from the thumb side, consists of the scaphoid, lunate, triquetrum, and pisiform bones. The distal row consists of the trapezium, trapezoid, capitate, and hamate bones. The palmar surface of the wrist is concave and forms a groove, and the ligament stretched over this groove converts it into the carpal tunnel, through which Muscle tendons, vessels, and nerves pass from the forearm to the hand.

The metacarpals are represented by five short bones, each consisting of a base, a shaft, and a head.

The phalanges of the digits are short bones that also consist of a base, a shaft, and a head. The head features a trochlear surface. The phalanges are designated as I, II, and III, or as proximal, middle, and distal. Each digit, except for the thumb, consists of three phalanges, whereas the thumb has only proximal and distal phalanges.

The bones of the upper limb articulate with each other through joints: the shoulder, elbow, and joints of the hand.

The shoulder joint is formed by the head of the humerus and the glenoid cavity of the scapula, which is deepened by the fibrocartilaginous glenoid labrum. It is a ball-and-socket joint that permits movements such as flexion and extension, abduction and adduction, medial and lateral rotation, as well as circumduction. The Joint Capsule is relatively loose and reinforced by a single ligament, the coracohumeral ligament. The tendon of the long head of the biceps brachii muscle passes through the joint cavity.

The elbow joint is formed by three bones: the humerus, ulna, and radius. Structurally, it is a compound joint. It consists of three articulations: the humeroulnar, humeroradial, and proximal radioulnar joints. These three joints share a common capsule reinforced by collateral ligaments.

In terms of shape, the elbow joint is a hinge joint, permitting movements such as flexion and extension around the frontal axis.

The bones of the forearm are connected to each other by two TYPES OF JOINTS: 1) a syndesmosis (via the interosseous membrane); and 2) the proximal and distal radioulnar joints, which function together as a single combined pivot joint. This allows the Rotation of the radius along with the hand outward (supination) and inward (pronation) around a vertical axis, while the ulna remains stationary.

The radiocarpal (wrist) joint is formed by the Articulation of the distal end of the radius with three bones of the proximal row of the carpus. Structurally, this joint is compound, and ellipsoid in shape. It allows movements such as flexion and extension, abduction and adduction, and circumduction. The joint capsule is reinforced by collateral ligaments.

Joints of the hand. The midcarpal joint is located between the First and Second rows of carpal bones, while plane intercarpal joints are formed between individual carpal bones. Together with the plane, slightly mobile carpometacarpal joints (II to V), they form the rigid Base of the hand.

The carpometacarpal joint of the thumb is saddle-shaped, allowing movements such as abduction and adduction, flexion and extension, as well as opposition of the thumb to the little finger and the reverse movement (reposition), which is unique to humans.

The metacarpophalangeal joints are condyloid in shape, while the interphalangeal joints are typical hinge joints. The capsules of all these joints are reinforced by collateral ligaments.

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