614 DISSECTION OF THE FOOT. 



Whilst beneath the annular ligament, or somewhat higher than it, the 

 nerve divides into the internal and external plantar branches of the foot. 



Its connections with surrounding parts are the same as those of the 

 artery ; but its position to the vessel changes, for it lies on the inner side 

 above the origin of the peroneal offset, but thence to the termination, on 

 the outer side. Its branches are muscular and cutaneous. 



Muscular brandies enter the deep flexors, and arise either separately 

 along the trunk, or together from the upper part of the nerve. There is 

 an offset for each of the muscles except the popliteus ; but the branch for 

 the tibialis is the largest, and that for the flexor pollicis lies on the pero- 

 neal artery. 



A cutaneous nerve of the sole of the foot (fig. 209, 4 ) begins above the 

 os calcis, and piercing the internal annular ligament as two or more 

 pieces, ends in the integuments of the inner and under parts of the heel ; 

 this nerve will be followed to its termination in the dissection of the foot 

 (fig. 210). 



The internal annular ligament stretches between the heel and the inner 

 ankle, and serves to confine the tendons of the deep layer of muscles of the 

 foot and toes. Attached by a pointed piece to the internal malleolus, the 

 fibres diverge, and are inserted into the os calcis. One border (upper) is 

 continuous with the fascia of the leg ; and the opposite gives attachment 

 to the abductor pollicis muscle of the foot. 



Beneath it are sheaths for the tendons. The innermost incloses the 

 tibialis posticus, lodged in a groove in the malleolus. Immediately be- 

 hind this is another space for the flexor digitorum. And about three- 

 quarters of an inch nearer the os calcis is the interval in which the flexor 

 pollicis lies, resting in a groove in the astragalus. Each sheath is lined 

 by a synovial membrane. 



Between the tendons of the two flexors of the digits are placed the 

 tibial vessels and nerve. 



SECTION V. 



SOLE OF THE FOOT. 



Position. The foot is to be placed over a block of moderate thickness 

 with the sole towards the dissector ; and the part is to be made tense by 

 fixing the heel with hooks, and by separating, and by fastening apart the 

 toes. 



Dissection, The skin is to be raised as two flaps, inner and outer, by 

 means of one incision along the centre of the sole from the heel to the 

 front ; and by another across the foot at the root of the toes. Afterwards 

 the skin is to be removed from each toe, and the digital vessels and nerves 

 on the sides are to be dissected out at the same time. 



In the fat near the heel the student should follow the cutaneous nerve 

 of the sole (supra) ; and he may trace out, at a little distance from each 

 border of the foot, some small branches of the plantar nerves and arteries. 



The subcutaneous fat is very abun ant. and forms a thick cushion over 

 the parts that press most on the ground in standing, viz., over the os 

 calcis, and the metatarso-phalangeal articulations. 



