Commonest injury is in the radial groove secondary to humeral fractures
Below this it enters the radial tunnel, between brachialis and brachioradialis,
The tunnel begins proximally at the level of the capitellum and extends for approximately 5cm to reach the supinator.
Impingement by fibrous bands, tendon margins and prominent vessels, a fibrous arch from the lateral head of the triceps muscle, fibrous bands around the radiocapitellar joint or the tendinous edge of the extensor carpi radialis brevis.
The radial nerve shares this location with multiple vessels and the vascular arcade of the recurrent radial artery, known as the leash of Henry
Compression of the radial nerve or its branches can also result from trauma, space-occupying lesions, or inflammatory disease.
POSTERIOR INTEROSSEUS NERVE
The nerve divides into superficial and deep branches at the proximal border of the supinator muscle.
The deep branch or posterior interosseous nerve (PIN) is a motor nerve, innervating the supinator and most of the wrist and finger extensors.
It passes through the two heads of supinator to emerge in the posterior compartment of the forearm.
the PIN may be impinged by the ligament of Frohse a fibrous arch which lies at the leading edge the superficial head of the supinator.
Fibrous bands occurring within the distal supinator close to the point where the nerve emerges may also compress
Entrapment in all these locations may be more prominent after strenuous muscular effort. Athletes, particularly those in sports dependent on upper limb development, may find that these natural areas of impingement can be further compromised by muscle hypertrophy.
Best for muscle denervation, earliest changes not visible on US
Better at tracking the nerve than MRI
Willdetect small changes in calibre
May get clue from Tinels signs
