Anatomy of the Humerus Bone Quiz

Bones of the Upper Limb

• The upper limb consists of the clavicle and scapula, which form the pectoral/shoulder girdle, followed by the humerus, radius, and ulna in the forearm, and the carpals, metacarpals, and phalanges in the hand.

Clavicle

• The clavicle is a long bone that lies horizontally and is palpable throughout its length.
• It is the first bone to ossify through intramembranous ossification.
• The clavicle has no medullary cavity and is sometimes pierced by cutaneous (supraclavicular) nerves.

Scapula

• The scapula has a costal surface, dorsal surface, and borders (superior, lateral, and medial).
• The scapula has angles (superior, inferior, and lateral) and a glenoid cavity that articulates with the head of the humerus.
• To determine the side of the scapula, the glenoid cavity should face laterally, the dorsal surface bearing the spine should face backwards, and the coracoid process should point forwards and laterally.

Humerus

• The humerus has a greater tubercle, head, anatomical neck, surgical neck, and shaft.
• The greater tubercle is a large projection that gives insertion to the supraspinatus, infraspinatus, and teres minor muscles.
• The head of the humerus articulates with the glenoid cavity of the scapula to form the shoulder joint.
• The anatomical neck is the constricted region of the head, while the surgical neck is the junction between the upper end and shaft.
• The shaft of the humerus has a deltoid tuberosity and radial groove.

Forearm Bones (Radius and Ulna)

• The radius and ulna are situated in the forearm, with the ulna on the medial side and the radius on the lateral side.
• The ulna has an olecranon process, coronoid process, trochlear notch, shaft, and radial notch for articulation with the head of the radius.
• The radius has a head, neck, radial tuberosity, shaft, and styloid process.

Carpal Bones

• The carpals are eight in number, arranged in two rows (proximal and distal).
• The proximal row consists of the scaphoid, lunate, triquetrium, and pisiform bones.
• The distal row consists of the trapezium, trapezoid, capitate, and hamate bones.

Joints of the Upper Limb

• The shoulder joint is a synovial ball-and-socket joint between the head of the humerus and the glenoid cavity of the scapula.
• The elbow joint is a synovial hinge joint between the distal humerus and the proximal radius and ulna.
• The proximal radioulnar joint is a synovial pivot joint between the head of the radius and the radial notch of the ulna.
• The distal radioulnar joint is a synovial pivot joint between the head of the ulna and the ulnar notch of the radius.

Movements of the Forearm

• Supination is the movement where the palm faces anteriorly, aided by the supinator muscles and biceps.
• Pronation is the movement where the dorsum of the hand faces anteriorly, aided by the pronator teres and pronator quadratus muscles.

Wrist Joint

• The radiocarpal joint (wrist joint) is a synovial ellipsoid joint between the distal end of the radius and the proximal row of carpal bones.

Fractures and Injuries

• The clavicle is susceptible to fracture due to falls on the shoulder or outstretched hand.
• The scapula can be fractured, but it is rare.
• The humerus can fracture at the surgical neck, which can injure the axillary nerve and posterior circumflex humeral vessels.
• The radius and ulna can fracture, causing damage to the radial nerve and profunda brachii vessels.