162 PRACTICAL ANATOMY. 



and palmar fascia, and is inserted into the skin of the hypothenar eminence. It 

 is a corrugator of the integument. 



The anterior annular ligament (Fig. 1 1 1) has passing under it the follow- 

 ing structures : 



1. The median nerve and its nutrient artery arteria comes nervi mediani. 



2. The flexor sublimis digitorum musculus perforatus. 



3. The flexor profundus digitorum musculus perforans. 



4. 1\i& flexor longus pollicis between the heads of the flexor brevis. 



To the inner side of the anterior annular ligament, and intimately related 

 thereto, you will find the flexor carpi ulnaris ; to the outer side, the flexor 

 carpi radialis. Inserted into the anterior annular ligament, and passing in 

 front of the same, is the palmaris longus muscle. (Fig. no.) To the ulnar 

 side is the ulnar, and to the radial side is the radial, artery. (Fig. 117.) 

 This anterior annular ligament is a specialized part of the deep fascia. It is 

 attached internally to the pisiform bone and unciform process of the unciform 

 bone; externally, to the scaphoid tuberosity and os trapezium. (Fig. 109.) 

 Cut through the annular ligament ; pull the sides forcibly apart as far as pos- 

 sible. There are two portions of the palmar bursa : (i) The radial, correspond- 

 ing to the flexor longus hallucis ; (2) the ulnar, corresponding to the flexor 

 sublimis digitorum and flexor profundus digitorum. (Fig. 107.) 



To Dissect the Median Nerve in the Hand (Fig. 1 1 1). You will now see the 

 median nerve, as large as a lead-pencil, lying on the flexor sublimis digitorum. 

 This nerve is involved in the synovial membrane, and it will require the aid of 

 the forceps to liberate the same. Place your left index finger under the nerve, 

 carefully lifting the same upward ; now begin to trace out the following branches 

 (Fig. in): (i) To the thumb ; (2) to the index finger, the middle finger, and 

 radial side of the ring finger ; (3) a communicating branch to the ulnar nerve. 

 You will see these branches given off from an enlargement. Trace the branches 

 downward and observe them passing behind the superficial palmar arch. (Figs. 

 1 1 1 and 1 13.) 



The branches of the median nerve, after passing behind the superficial palmar 

 arch, accompany arterial branches of the superficial and deep palmar arches to 

 the fingers. (Fig. 111.) These arteries and nerves are called digital branches. 

 Note that at the superficial palmar arch the nerves lie behind, but in the fingers 

 the nerves lie in front of, the arteries. Trace these digital arteries and nerves 

 to the ends of the finger, and see the distal digital anastomotic arterial arch. 



( Fi g- "3-) 



The Ulnar Nerve in the Hand. Find the ulnar nerve crossing the annular 

 ligament (not under it). It lies to the ulnar side of the ulnar artery, and some- 

 what deeper. Trace it down and find it dividing into two branches: (i) The 

 superficial palmar ; (2) the deep pa/mar. The former gives off branches to the 

 skin, to the palmaris brevis muscle, and digital branches which accompany 

 arteries to the little finger and one-half of the ring finger. Trace these branches 

 to 'the finger end and observe the distal digital anastomotic nerve loop. (Fig. 

 Hi.) The deep palmar branch of the ulnar nerve accompanies the deep arch, 

 and will be described in its proper place on page 164. 



The musculi lumbricales (Fig. 112) are four in number. Cut the tendons 

 of the flexor sublimis as shown in figure 112. These muscles arise from the 

 tendons of the flexor profundus digitorum muscle. Trace them on the thumb 

 side, to the extensor communis digitorum, where they are inserted. The ulnar 

 two interossei muscles are supplied by the ulnar, the radial two by the median, 

 nerve. 



The thenar muscles, or muscles of the thumb (Figs. 109 and 114): 



I. The abductor pollicis, abducts first phalanx. 



