Ulnar nerve entrapment

 

The ulnar nerve is one of the three main nerves inthe arm. It travels from your neck down into your hand

Where the nerve can be compressed ??

Cubital nerve ( in yellow)

Cubital nerve ( in yellow)

Cubital Tunnel:

  • Roof: formed by FCU fascia and Osborne's ligament (travels from the medial epicondyle to the olecranon)

  • Floor: formed by posterior and transverse bands of MCL and elbow joint capsule

  • Walls: formed by medial epicondyle and olecranon

 

Some factors put you more at risk for developing cubital tunnel syndrome. These include:

  • Prior fracture or dislocations of the elbow

  • Bone spurs/ arthritis of the elbow

  • Swelling of the elbow joint

  • Cysts near the elbow joint

  • Repetitive or prolonged activities that require the elbow to be bent or flexed

ulnar tunnel.jpg
ulnar nerve1.jpg

Symptoms

  • Numbness and tingling in the hand and fingers

  • Interosseous and first web space atrophy 

  • Ring and small finger clawing

  • Observe ulnar nerve subluxation over the medial epicondyle as the elbow moves through a flexion-extension arc

  • Search paralysis of intrinsic muscles (adductor pollicis, deep head FPB, interossei, and lumbricals 4 and 5) which leads to

    • weakened grasp: from loss of MP joint flexion power

    • weak pinch: from loss of thumb adduction (as much as 70% of pinch strength is lost)

    • Froment sign : compensatory thumb IP flexion by FPL (AIN) during key pinch compensates for the loss of MCP flexion by adductor pollicis (ulna n.) adductor pollicis muscle normally acts as a MCP flexor, first metacarpal adductor, and IP extensor

    • Jeanne sign: compensatory thumb MCP hyperextension and thumb adduction by EPL (radial n.) with key pinch compensates for loss of IP extension and thumb adduction by adductor pollicis (ulna n.)

    • Wartenberg sign persistent small finger abduction and extension during attempted adduction secondary to weak 3rd palmar interosseous and small finger lumbrical

    • Masse sign : palmar arch flattening and loss of ulnar hand elevation secondary to weak opponens digiti quinti and decreased small finger MCP flexion

External sources of compression

  • fractures and medial epicondyle nonunions

  • osteophytes

  • heterotopic ossification

  • tumors and ganglion cysts

  • Associated conditions: cubitus varus or valgus deformities, medial epicondylitis, burns,  elbow contracture release.

cubital tunnel.jpg