THE ABDOMINAL WALLS. 119 



digitorum and abductor minimi digiti. The external plantar artery and nerve lie for a short portion of 

 their course in the interval between these muscles. Approaching the prominent base of the fifth meta- 

 tarsal bone, the artery disappears from view by turning inward under cover of the flexor tendon. At 

 the same point the external plantar nerve divides into its superficial and deep divisions. The deep 

 division of the external plantar nerve cannot be dissected at present, as it accompanies the external 

 plantar artery. The superficial division, however, should be traced to its distribution." (Cunningham.) 



Flexor brevis digitorum or flexor perforatus, 401-2 ; Fig. 293. (399) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 

 Abductor hallucis, 401 ; Fig. 293. (398-9) 



Origin: Outer head ; Inner head. Insertion. Structure. 



Nerve-supply. Action. Relations. Variations. 

 Abductor minimi digiti, 402-3 ; Fig. 293. (399-400) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Divide the muscles of the superficial group near their origin from the os calcis and turn them forward ; 

 note the arterial and nerve branches to each, expose the superficial portion of the plantar arteries and the 

 plantar nerves. 



Internal plantar artery, 631-2 ; Fig. 378. (619-20) 



Relations. Branches : Muscular branches. Cutaneous branches. 



Articular. Anastomotic. Superficial digital. 



External plantar artery (superficial portion), 628-9 ; Fig. 378. (616-17) 

 Relations in the first part of its course, 629-30. (617) 

 Branches of the external plantar artery : 



Muscular branches. Calcanean. Cutaneous. Anastomotic. 

 The veins of the foot and leg, 685. (671) 

 Internal plantar nerve; cutaneous branches, 863 ; Fig. 469. (843) 



First digital branch. Second branch. Third branch. Fourth branch. 

 External plantar nerve, 863 ; Fig. 469. (843) 

 Superficial division : 

 Internal branch. 

 External branch. 



Expose the tendon of the flexor longus digitorum, and trace forward each division to its terminal inser- 

 tion. 



Flexor longus digitorum, 396 ; Fig. 294. (393-4-5) 



Insertion. Structure. Action. 

 Flexor accessorius digitorum pedis, 404 ; Fig. 294. (400-1) 



Origin : Inner head ; Outer head. Insertion. Structure. 

 Xerve-supply. Action. Relations. Variations. 

 The four lumbricales, 404-5 ; Fig. 294. (401-2) 



Origin. Insertion. Structure. Xerve-supply. Action. Relations. 

 Flexor longus hallucis, 398 ; Fig. 294. (395) 

 Insertion. Structure. Action. 



To expose the next layer of muscles, divide the flexor accessorius at its origin, cut the tendons of the 

 flexor longus digitorum and the flexor longus hallucis in front of the annular ligament and turn forward 

 to the toes. Leave the plantar vessels and nerves in place. 



Flexor brevis hallucis, 405-6 ; Figs. 294-5. (402-3) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 

 Adductor hallucis, 406-7 ; Fig. 295. (403-4) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 

 Transversus pedis, 407 ; Fig. 295. (404) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 

 Flexor brevis minimi digiti, 4078; Fig. 295. (4045) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Divide the flexor brevis and the adductor hallucis at their origin, and throw them forward to expose the 

 plantar arch and the deep branch of the external plantar nerve. 



Plantar artery ; second part of its course, 630-1 ; Fig. 379. (618-19) 

 Branches : Articular. 



Digital or plantar digital : 

 Collateral digital arteries. 



