Forearm bones- Radius & Ulna

In this lecture will see the bones of the forearm-

ulna

Ulna

-It is located on the medial aspect of the forearm and is longer than the radius.

-At the proximal end of the ulna is the olecranon, which forms the prominence of the elbow.

-With the olecranon, an anterior projection of the coronoid process articulates with the trochlea of the humerus.

– The trochlear notch is a large curved area between the olecranon and coronoid process that forms part of the elbow joint.

-Lateral and inferior to the trochlear notch is a depression, the radial notch, which articulates with the head of the radius.

-Inferior to the coronoid process is the ulnar tuberosity, the biceps brachii muscle attaches with it.

-The distal end of the ulna consists of a head that is separated from the wrist by a disc of fibrocartilage.

-A styloid process is located on the posterior side of the ulna’s distal end.

radius

Radius

-It is the smaller bone of the forearm and is located on the lateral aspect of the forearm.

-It is narrow at its proximal end and widens at its distal end.

-At the proximal end, there is a disc-shaped head that articulates with the capitulum of the humerus and the radial notch of the ulna.

-Inferior to the head is the constricted neck & just below to that is radial tuberosity, a point of attachment for the tendons of the biceps brachii muscle.

-The shaft of the radius becomes widen distally & form a styloid process on the lateral side.

-The distal end of the radius contains the ulnar notch, which articulates with the head of the ulna.

-The ulna and radius articulate with the humerus at the elbow joint at 2 areas, the head of the radius articulate with the capitulum of the humerus, and the trochlear notch of the ulna articulates with the trochlea of the humerus.

-The ulna and the radius connect with one another at three sites. A fibrous connective tissue, the interosseous membrane joins the shafts of the two bones, and at the proximal, the head of the radius articulates with the ulna’s radial notch, it is the proximal radioulnar joint, Distally, the head of the ulna articulates with the ulnar notch of the radius, is the distal radioulnar joint.

-The distal end of the radius articulates with three bones of the wrist the lunate, the scaphoid, and the triquetrum and forms the radiocarpal (wrist) joint.

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