1.- Describe how the radius an

The Ulna

Anatomically, the ulna is located medially to the radius,placing it near the little finger. The ulna is slightly larger thanthe radius.

Proximally, there are five key regions of the ulna:

The olecranon is a projection of bone that extends proximallyfrom the ulna.

The triceps brachii muscle attaches to the ulna superiorly.

The cornoid process, together with the olecranon, forms thetrochlear notch where it articulates with the trochlea of thehumerus.

Laterally to the trochlear notch lies the radial notch, whicharticulates with the head of the radius to form the proximalradioulnar joint.

Immediately distal to the coronoid process is the tuberosity ofulna, to which the brachialis muscle attaches.

The shaft of the ulna is triangular and numerus muscles involvedin pronation and flexion of the forearm attach to its surface.

Distally, the ulna is much smaller and terminates with a roundedhead that articulates with the ulnar notch of the radius to formthe distal radioulnar joint. The styloid process of the ulnaextends distally and is the site of attachment for ligaments foundin the wrist.

The Radius

Anatomically, the radius is located laterally to the ulnaplacing it near the thumb. The radius is slightly smaller than theulna and pivots around the ulna to produce movement at the proximaland distal radioulnar joints.

Proximally, the radius terminates with a disk-shaped head thatarticulates with the capitulum of the humerus and the radial notchof the ulna. Immediately below the head lies the radial tuberosityto which the biceps brachii attaches. As with the ulna, the shaftof the radius is triangular in shape and numerous muscles,including the protonator teres, attach to it.

Distally the radius expands, medially the ulnar notcharticulates with the head of the ulnar. Immediately adjacent to theulnar notch, the radius articulates with the scaphoid and lunatecarpal bones to form part of the wrist.