Bones and joints The bones of the forearm are the
radius (located on the lateral side) and the
ulna (located on the medial side)
Radius Proximally, the head of the radius articulates with the
capitulum of the humerus and the radial notch of the ulna at the
elbow. The
articulation between the radius and the ulna at the elbow is known as the
proximal radioulnar joint. Distally, it articulates with the ulna again at the
distal radioulnar joint. It forms part of the
wrist joint by articulating with the
scaphoid at its lateral aspect and with the
lunate at its medial aspect.
Ulna Proximally, the
trochlear notch of the ulna articulates with the
trochlea of the humerus and the
radial notch articulates with the head of the radius at the
elbow. Distally it forms part of the
distal radioulnar joint and also articulates with the
wrist.
Muscles • "E/I" refers to "extrinsic" or "intrinsic". The intrinsic muscles of the forearm act on the forearm, meaning, across the elbow joint and the
proximal and
distal radioulnar joints (resulting in
pronation or
supination), whereas the extrinsic muscles act upon the hand and wrist. In most cases, the extrinsic anterior muscles are
flexors, while the extrinsic posterior muscles are
extensors. • The brachioradialis, flexor of the forearm, is unusual in that it is located in the
posterior compartment, but it is actually in the anterior portion of the forearm. • The
anconeus is considered by some as a part of the
posterior compartment of the arm.
Nerves :
See separate nerve articles for details on divisions proximal to the elbow and distal to the wrist; see Brachial plexus for the origins of the median, radial and ulnar nerves. •
Median nerve – interior nerve of the anterior compartment (
PT,
FCR,
PL,
FDS). •
anterior interosseous nerve (supplies
FPL, lat. 1/2 of
FDP,
PQ). •
Radial nerve – supplies muscles of the posterior compartment (
ECRL,
ECRB). •
Superficial branch of radial nerve •
Deep branch of radial nerve, becomes
Posterior interosseus nerve and supplies muscles of the posterior compartment (
ED,
EDM,
ECU,
APL,
EPB,
EPL,
EI). •
Ulnar nerve – supplies some medial muscles (
FCU, med. 1/2 of
FDP).
Vessels •
Brachial artery •
Radial artery •
Radial recurrent artery •
dorsal metacarpal artery •
Princeps pollicis artery •
Ulnar artery •
Anterior ulnar recurrent artery and
posterior ulnar recurrent artery •
Common interosseous artery •
Posterior interosseous artery •
Anterior interosseous artery Other structures •
Interosseous membrane of forearm •
Annular ligament of ulna == Function ==