ABDUCTOR POLLICIS. 



271 



Plantar Region. 

 First Layer. 



Abductor pollicis, 

 Abductor minimi digiti, 

 Flexor brevis digitorum. 



Dissection. The sole of the foot is best dissected by carrying an 

 incision around the heel, and along the inner and outer borders of the 

 foot, to the great and little toes. This 

 incision should divide the integument Fig. 109.* 



and superficial fascia, and both together 

 should be dissected from the deep fascia, 

 as far forward as the base of the pha- 

 langes, where they may be removed 

 from the foot altogether. The deep 

 fascia should then be removed, and the 

 first layer of muscles will be brought 

 into view. 



The ABDUCTOR POLLICIS lies along 

 the inner border of the foot ; it arises by 

 two heads, between which the tendons 

 of the long flexors, arteries, veins, and 

 nerves enter the sole of the foot. One 

 head arises from the inner tuberosity 

 of the os calcis, the other from the 

 internal annular ligament and plantar 

 fascia. Insertion, into the base of the 

 first phalanx of the great toe, and into 

 the internal sesamoid bone. 



Relations. By its superficial surface 

 with the internal portion of the plantar 

 lascia. By its deep surface with the 

 flexor brevis pollicis, musculus acces- 

 sorius, tendons of the flexor longus di- 

 gitorum and flexor longus pollicis, ten- 

 dons of the tibialis anticus and posti- 

 cus, the plantar vessels and nerves, and 

 the tarsal bones. On its outer border 



with the flexor brevis digitorum, from which it is separated by a 

 vertical septum of the plantar fascia. 



* The first layer of muscles in the sole of the foot ; this layer is exposed by 

 the removal of the plantar fascia. 1. The os calcis. 2. The posterior part of 

 the plantar fascia divided transversely. 3. The abductor pollicis. 4. The 

 abductor minimi digiti. 5. The flexor brevis digitorum. 6. The tendon of 

 the flexor longus pollicis muscle. 7, 7. The lumbricales. On the second and 

 third toes, the tendons of the flexor longus digitorum are seen passing through 

 the bifurcation of the tendons of the flexor brevis digitorum. 



