The forearm consists of two parallel bones, the Radius, and the Ulna. They are connected along their entire length by an Interosseous Membrane, and articulate with each other at small radioulnar joints.

Ulna

The Ulna runs along the ‘little finger’ side of the forearm and it’s main responsibility is in forming the elbow joint with the Humerus. The ‘elbow end’ resembles a spanner and its with this that it articulates with the upper arm. The Olecranon is the bony point of the elbow. The other end of the Ulna (head) articulates with the Radius. It is separated from the wrist by fibrocartilage and has basically no role in hand movement.

Radius

The Styloid Process serves as an attachment site for ligaments that run to the wrist.

B. Radius

The bone of the forearm that runs along the thumb side.

C. Radial Tuberosity

Attachment site for the Biceps Brachii muscle of the upper arm.

D. Neck of Radius

Situated between the Head and the Radial Tuberosity

E. Head of Radius

Shaped like the head of a nail, it articulates with the Humerus, and the Radial Notch of the Ulna

F. Olecranon Process (Elbow)

The prominent projection at the elbow end of the Ulna.

G. Trochlear Notch

The Trochlea Notch attaches to the Trochlea of the Humerus to form the elbow joint

H. Coronoid Process

Together with the Olecranon Process, grips the Humerus to form the hinge joint of the elbow

I. Proximal Radio-Ulnar Joint

A synovial, pivot joint between the Radius and the Ulna. Located at the elbow end of the forearm

J. Ulna

The bone of the forearm that runs along the 'little finger' side.

K. Interosseous Membrane

A flexible membrane connecting the Radius and Ulna along their length

L. Head of Ulna

Is seperated from the wrist by a disc of fibrocartilage and plays no role in hand movement

M. Styloid Process of Ulna

The Styloid Process serves as an attachment site for ligaments that run to the wrist.

N. Distal Radio-Ulna Joint

A synovial, pivot joint between the Radius and the Ulna. Located at the wrist end of the forearm