Fig. 95. Palm of Hand (Left); Superficial Layer. 



The Palmar Fascia has been removed almost completely, the Annular Ligament 

 partly, and all the veins have been cut away. 



Arteries. At the wrist the Ulnar Arter}' lies between the Annular 

 Ligament and the Transverse Carpal Ligament ; it may, at this point — in contiguity 

 with the Pisiform Bone — give off the branch which joins the deep palmar arch, 

 passing to the deeper layers in association with the deep branch of the Ulnar 

 Nerve (Fig. 96). 



In the palm of the hand, covered onty by the palmar fascia, lies the 

 Superficial Palmar Arch. This arch is formed by the continuation of the trunk 

 of the Ulnar Artery, and is often completed by an anastomosing branch from 

 the Radial Artery. (Cf. text, Fig. 92.) 



Nerves. In the lower part of the forearm the Median Nerve lies on 

 the outer aspect of the Palmaris Longus Muscle, or in the case of absence of 

 this muscle on the outer side of the Flexor Sublimis Digitorum Muscle. In the 

 palm of the hand the nerve is more superficial than the tendons. (Cf. Figs. 103, 104.) 

 The Median Nerve supplies the palmar (flexor) aspect of the three outer fingers 

 and the outer border of the fourth finger whereas the Ulnar Nerve supplies the 

 palmar aspect of the fifth finger and the inner border of the fourth finger. 



The Median Nerve supplies 



a) all the short muscles of the thumb except the Adductor Transversus 

 Muscle and the Adductor Obliquus Muscle; 



b) the two Outer Lumbricalis Muscles, and a part of the third (which also 

 derives a supply from the Ulnar Nerve — Bardeleben and Frohse). 



The Ulnar Nerve supplies 



a) a part of the third Lumbricalis Muscle as well as the fourth; 



b) all the muscles of the little finger; 



c) all the interosseous muscles; 



d) the Adductor Transversus Muscle and the x\dductor Obliquus Muscle 

 of the Thumb. 



When the hand is slightly dorsiflexed (cf. text, Fig. 89) the Ulnar Artery 

 and a part of the Ulnar Nerve are shewn above the Annular Ligament. The 

 Tendons of the Flexor Sublimis Digitorum Muscle are arranged in two layers — 

 those to the 3rd and 4th fingers are situated more superficial (cf. Fig. 91), those 

 to the 2nd and 5th fingers at a deeper plane. The Median Nerve is contiguous 

 to the tendon of the 3rd finger. 



The sheath of the Flexor Carpi Radialis Tendon is laid open at its 

 proximal end ; the Extensor Ossis Metacarpi Pollicis sends a slip to the Abductor 

 Pollicis Muscle. The Thenar Eminence is chiefly composed of muscles whereas 

 upon the Hypothenar Eminence is a thick layer of fat containing a cutaneous 

 muscle — the Palmaris Brevis Muscle. 



The Palmar Fascia is of great practical importance, — it is very tense 

 and strong, bridging over the space between the Thenar and Hypothenar Eminences ; 

 its intimate connection with the skin explains why the latter cannot be picked 

 up and why celluhtis of the hand is dangerous. This dense fascia prevents the 

 infective process from spreading towards the surface while the delicate tendon- 

 sheaths and the loose tissue which surrounds them affords a favourable means of 

 extension. Injury is well known to produce very free haemorrhage due to the 

 abundant anastomosis in this region. 



The nerve supply is most complete, numerous Pacinian Corpuscles are 

 observed (cf. Fig. 93). 



