20 



the large A. digitalis communis and both artery and nerve are in close 

 relation with the flexor tendons. Note that near the middle of the meta- 

 carpus the nerve gives off a large branch which crosses very obliquely the 

 posterior face of the flexor tendons and joins the N. volaris lateralis a little 

 above the distal extremity of the rudimentary metacarpal (PI. Ill, 28). 

 At the level of the sesamoid bones of the fetlock, the nerve divides into 

 two, sometimes three, branches, viz., an anterior, a middle, if present, and a 

 posterior branch (PL III, 30, 31, 32). These branches are of very unequal 

 size, the posterior being much the largest and the most important. This 

 branch is the one that is cut in the operation of low neurectomy. The anter- 

 ior branch descends in front of the vein and is distributed to the skin on the 

 anterior face of the digit and to the coronary band or matrix. The middle 

 branch is small and irregular; it descends between the artery and vein and 

 is generally formed by the union of several small branches which cross over 

 the artery before uniting. This branch terminates in the coronary band 

 or matrix and the sensitive laminae. The posterior branch lies close behind 

 the artery, except at the fetlock, where the nerve is more superficial than the 

 artery. This posterior branch accompanies the digital artery and will be 

 traced with it. It is distributed to the sensitive laminae, sole and frog. 



A. digitalis lateralis and A. digitalis medialis are formed by the bifur- 

 cation of the digitalis communis near the distal third of the metacarpus. 

 Each artery passes over the outer surface of the corresponding sesamoid 

 bone at the fetlock, and descends parallel to the borders of the deep flexor 

 tendon to the volar foramina of the third phalanx; in the semilunar canal 

 of this bone the two arteries anastomose with each other. Expose the 

 artery of one side, as follows : ■ remove the lateral cartilage and the anterior 

 or apical two-thirds of the plantar cushion; remove also, the portion of 

 the deep flexor tendon that is exposed by the removal of the anterior part 

 of the plantar cushion, i.e. the portion of tendon in relation to the navicular 

 bone and the semilunar crest of the third phalanx. Each digital artery is 

 accompanied by a vein and the two or three branches of the volar nerves. 

 Proximal to the fetlock the artery lies deeply- and is covered by the vein 

 and nerve; at the fetlock the three structures lie at the same level, the vein 

 being anterior and the large posterior branch of the nerve back of the artery. 

 The anterior branch of the volar nerve crosses obliquely the digital 

 artery and vein at, or a little below, the fetlock (PI. Ill, 30). The vessels 

 and nerves are crossed obliquely by a small ligamentous band extending 

 from the ergot to the fascia at the side of the first interphalangal or pastern 

 joint (PI. Ill, 13). 



