Bones and joints of the upper limb

2. The clavicle is the only [blank_start]horizontal[blank_end] long bone and develops from [blank_start]membrane[blank_end]. The lateral end of the clavicle is called the [blank_start]acromion[blank_end] of the scapula and is flattened in shape. The medial end of the clavicle is called the [blank_start]sternal end[blank_end], articulates with the manubrium of the sternum and is [blank_start]rounded[blank_end] in shape. The clavicle is an [blank_start]S-shaped[blank_end] curve with the medial 2/3rds bulging outwards and the lateral 1/3rd bulging inwards, the point in which the clavicle changes shape is vulnerable to [blank_start]fracture[blank_end]. The superior clavicle surface is [blank_start]smooth[blank_end] whilst the inferior clavicle surface is [blank_start]rough[blank_end].

3. The scapula is a [blank_start]triangular[blank_end] shaped bone which is on the posterior surface of the thoracic cage. It has 3 borders: the medial, lateral and superior border. The [blank_start]lateral[blank_end] border is closest to the upper limb, the [blank_start]medial[blank_end] border is closest to the vertebrae. The posterior surface has a [blank_start]spine[blank_end] separating the supraspinous fossa and infraspinous fossa. The anterior scapular surface has the [blank_start]subscapular[blank_end] fossa. The lateral end of the scapular spine is called the [blank_start]acromion[blank_end]. The [blank_start]glenoid fossa[blank_end] is the shallow depression which receives the head of the humerus. The [blank_start]glenoid labrum[blank_end] is the fibrocartilaginous rim that works to deepen the socket for the glenohumeral joint.

4. The humerus is the long bone of the arm. It has a superior articulation with the [blank_start]scapula[blank_end] at the shoulder and inferior articulation at the [blank_start]elbow[blank_end] with the [blank_start]radius[blank_end] and [blank_start]ulna[blank_end]. At the proximal end of the scapula, there is a greater tubercle, a lesser tubercle and an [blank_start]inter-tubercular[blank_end] groove between them. The [blank_start]anatomical[blank_end] neck of the humerus is where the epiphyseal growth plate is located whilst the [blank_start]surgical[blank_end] neck is the region that the humerus changes in diameter, predisposing this region to fracture. The head of the humerus articulates with the [blank_start]glenoid fossa[blank_end] of the scapula and is lined by [blank_start]hyaline cartilage[blank_end]. The humerus is a long bone, thus it has a shaft (diaphysis). The distal humerus has medial and lateral [blank_start]epicondyles[blank_end]. The [blank_start]medial[blank_end] epicondyle is more close to the skin. The [blank_start]trochlear[blank_end] is adjacent to the medial epicondyle and articulates with the trochlear notch of the ulna and the [blank_start]capitulum[blank_end] is adjacent to the lateral epicondyle and articulates with the radius head.

6. The radius lies [blank_start]laterally[blank_end] in the forearm and articulates with the [blank_start]capitulum[blank_end] of the humerus. At the proximal end, the radius has a flat, discoid [blank_start]head[blank_end] at the elbow, a neck and a radial tuberosity that is the region of insertion of the [blank_start]biceps brachii[blank_end] muscle. Inferiorly, at the wrist, the radius has a [blank_start]styloid process[blank_end].

7. The [blank_start]interosseous membrane[blank_end] is the fibrous membrane between the radius and ulna, forms a [blank_start]pivot[blank_end] joint which allows supination and pronation of the arm and provides a large surface area as a site of muscle attachment.

8. The hand has 29 bones. There are [blank_start]8[blank_end] carpal bones, 5 metacarpals and [blank_start]14[blank_end] phalanges. The proper name for knuckles is the [blank_start]metacarpophalangeal[blank_end] joint. A sesamoid bone is formed in the [blank_start]tendon[blank_end] of a muscle and is found in the thumb.

9. Joints can be classified based on the type of interlinking substance. Fibrous joint examples are the [blank_start]sutures[blank_end] of the skull and the [blank_start]interosseous membrane[blank_end] between the radius and ulna. These allow for relatively limited movement. Cartilaginous joint examples include the [blank_start]costal cartilages[blank_end] of the thoracic cage and the [blank_start]intervertebral discs[blank_end] of the spine. Synovial joints allow for the most movement and examples include the ball and socket joints of the hip and shoulder.

10. Select the true statement about synovial joints:

13. The 3 joints of the [blank_start]pectoral[blank_end] girdle include the sternoclavicular, acromioclavicular and glenohumoral joint.

The ulna lies medially in the forearm and articulates with the [blank_start]trochlear[blank_end] of the humerus. The head of the ulna is inferior and at the wrist, whilst the head of the [blank_start]radius[blank_end] is [blank_start]superior[blank_end] and at the elbow. The trochlear notch of the ulna has a lower lip called the [blank_start]coronoid process[blank_end] and an upper lip called the [blank_start]olecranon[blank_end]. The trochlear tuberosity is under the trochlear notch and is for the insertion of the [blank_start]brachioradialis[blank_end] muscle.

11. Joints can be classified based on how many planes they allow movement in. Examples of uniaxial joints includes the [blank_start]hinge[blank_end] joint of the elbow (allows flexion and extension) and the [blank_start]pivot[blank_end] joint of the interosseous membrane (allows supination and pronation), examples of biaxial joints include the [blank_start]condyloid[blank_end] joints of the wrist (allowing adduction, abduction, flexion and extension). Examples of multi-axial joints include ball and socket joints and the saddle joint of the thumb which is between the [blank_start]trapezius[blank_end] and [blank_start]1st[blank_end] metacarpal bones.