Radial Nerve Deep Branch

Several synovial bursae around the elbow joint lessen friction between bones and the overlying skin and soft-tissue structures. The most important are the olecranon bursa and the bidpitoradial bursa. The olecranon bursa is a large subcutaneous bursa which intervenes between the skin and the olecranon process over the posterior aspect of the elbow. The bidpitoradial bursa (cubital bursa) lies deep in the anterior compartment of the elbow, between the distal biceps tendon and the radial tuberosity, to reduce friction between, especially during pronation of the forearm (Skaf et al. 1999). In fact, the radial tuberosity rotates posteriorly during pronation and wraps the tendon around the radial cortex. During this movement, the bursa is tracked between the tendon and the bone (Fig. 8.8). When distended by fluid, the bicipitoradial bursa may surround the biceps tendon completely and may cause a mass effect on the adjacent branches of the radial nerve. 

The lateral aspect of the elbow is best examined with both elbows in extension, thumbs up, palms of the hands together (Barr and Babcock 1991). When examining the radial collateral ligament and the capsule, the elbow should be extended, keeping the hand pronated. Along the lateral elbow, high-resolution US can demonstrate the common extensor tendon, the lateral ulnar collateral ligament, the radial nerve with its superficial and deep (posterior interosseous nerve) branches, and the radio-capitellar joint. 

Fig. 8.46a,b. Posterior interosseous nerve syndrome, a Transverse 12-5 MHz US image obtained over the supinator area in patient with a previous radial head fracture and radial nerve deficit demonstrates the posterior interosseous nerve (arrowheads) entrapped within a hypoechoic scar (arrows) in the area of the supinator muscle (s). b Gross operative view shows the main trunk of the radial nerve (asterisks) as it splits into the superficial cutaneous sensory branch (arrowheads) and the deep posterior interosseous nerve (narrow arrows). This latter nerve is irregularly swollen as it passes over the bone (large arrows) as a result of the scar encasement visible in a... 

The adductor pollicis muscle is a fan-shaped muscle supplied by the deep branch of the ulnar nerve with two heads (oblique and transverse) of origin between which the radial artery passes. The oblique head arises from the second and third metacarpals... 

The thenar muscles are innervated by the recurrent branch of the median nerve and are basically responsible for the complex movement of the thumb. They include the superficial abductor pollicis brevis, the flexor pollicis brevis and the deep opponens pollicis muscles. The abductor pollicis brevis is a broad flat muscle located on the more lateral side of the thenar eminence. It arises from the radial side of the transverse carpal ligament and the tubercle of the trapezium and inserts into the base of the proximal phalanx. The flexor pollicis brevis is located medial to the abductor pollicis and has two muscular bellies the superficial head arises from the transverse carpal ligament and the tubercle of the trapezium, the deep head (first palmar interosseous muscle) from the trapezoid and the capitate. Both heads insert through the radial sesamoid over the metacar-... 

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