Elbow Nerves: MR Findings in 60 Asymptomatic Subjects—Normal Anatomy, Variants, and Pitfalls

Abstract

Increased SI of the ulnar nerve on fluid-sensitive images (60%), an atypical intermuscular course of the median nerve (17%), and an anconeus epitrochlearis muscle (23%) are common MR findings in asymptomatic elbows.

Elbow nerves: normal sonographic anatomy and identification of the structures potentially associated with nerve compression. A short pictorial-video article

“…Median nerve may be compressed by thickened lacertus fibrosus, the bicipital aponeurosis which descends medially, across the brachial artery and median nerve, to fuse with fascia of flexor muscles of the forearm [6] (Fig. 6).…”

Magnetic resonance imaging of the elbow

“…There are a number of anatomic variants around this region which can predispose an individual to developing ulnar neuritis. Thickening of the cubital tunnel retinaculum can result in dynamic compression of the nerve on elbow flexion, and is seen in up to 22% of the normal population (11). The anconeus epitrochlearis is a small accessory muscle that traverses over the cubital tunnel, present in up to 23% of the population (11).…”

“…Thickening of the cubital tunnel retinaculum can result in dynamic compression of the nerve on elbow flexion, and is seen in up to 22% of the normal population (11). The anconeus epitrochlearis is a small accessory muscle that traverses over the cubital tunnel, present in up to 23% of the population (11). In 10% of the population the cubital tunnel retinaculum is completely absent, which allows the ulnar nerve to sublux anteriorly over the medial epicondyle during flexion, which may result in friction neuritis (11).…”

“…The anconeus epitrochlearis is a small accessory muscle that traverses over the cubital tunnel, present in up to 23% of the population (11). In 10% of the population the cubital tunnel retinaculum is completely absent, which allows the ulnar nerve to sublux anteriorly over the medial epicondyle during flexion, which may result in friction neuritis (11). The normal ulnar nerve appears of intermediate T1 signal intensity and slightly increased T2 signal intensity, and is surrounded by a cuff of fat within the cubital tunnel (Fig.…”

“…Although there are a number of locations where the nerve can become entrapped, the nerve is most commonly entrapped within the cubital tunnel, resulting in cubital tunnel syndrome. A number of anatomic variants can result in ulnar neuritis, including thickening or absence of the cubital tunnel retinaculum, or an accessory anconeus epitrochlearis (11,(59)(60)(61). A variety of other conditions can result in compression of the ulnar nerve within the cubital tunnel, including prior fracture, medial collateral ligament injury, posteromedial osteophytes, synovitis, or other space-occupying lesions such as ganglia (62,63).…”