RADIAL NERVE
The radial nerve (C5 to C8, T1) is the
largest branch of the brachial plexus and is the main continuation of its posterior
cord. In the axilla, it lies behind the outer end of the axillary artery on
the subscapularis, latissimus dorsi, and teres major muscles. Leaving the
axilla, it enters the arm between the brachial artery and the long head of the
triceps brachii muscle.
Continuing downward and accompanied by
the deep brachial artery, the nerve pursues a spiral course behind the humerus,
lying close to the bone in the shallow radial nerve sulcus. It passes between
the long and medial and medial and lateral heads of the triceps brachii muscle
and then lies deep to the lateral head. On reaching the distal third of the arm
at the lateral margin of the humerus, it pierces the lateral intermuscular
septum to enter the anterior compartment of the arm. Then it descends anterior
to the lateral epicondyle of the humerus and the articular capsule of the elbow
joint, lying deep in the furrow between the brachialis muscle medially and the
brachioradialis and extensor carpi radialis longus muscles laterally. At this
point, it divides into its deep and superficial branches.
In the axilla, the radial nerve gives
off the small pos- terior brachial cutaneous nerve and a muscular branch
to the long head of the triceps brachii muscle.
In the arm, the radial nerve supplies
muscular, cutaneous, vascular, articular, and osseous branches. The first
muscular branch is long and slender, arising as the nerve enters the radial
nerve sulcus; it accompanies the ulnar nerve to the lower arm to supply the
distal part of the medial head of the triceps brachii muscle and to furnish
twigs to the elbow joint. A second, larger branch arises from the nerve as it
lies in the radial nerve sulcus; it soon subdivides into smaller branches that
enter the medial head of the triceps brachii muscle, with some twigs to the
humeral periosteum and bone. A stouter subdivision supplies the lateral head of
the triceps brachii muscle. It descends through the muscle accompanied by the
medial branch of the deep brachial artery.
It then penetrates and supplies the
anconeus muscle and sends branches to the humerus and the elbow joint.
Anterior to the lateral intermuscular
septum, the radial nerve gives muscular branches to the lateral part of the
brachialis, brachioradialis, and extensor carpi radialis longus muscles and,
occasionally, to the extensor carpi radialis brevis. Vascular branches and
twigs are furnished to the elbow joint.
Three cutaneous branches arise from
the radial nerve above the elbow the posterior brachial cutaneous, inferior lateral
brachial cutaneous, and posterior antebrachial cutaneous nerves.
Nerve Supply To The Elbow
Nerves reach the joint anteriorly from the musculocutaneous,
median, and radial nerves and posteriorly from the ulnar nerve and the radial
nerve branch to the anconeus muscle.
