432 



Fig. 



SURGICAL ANATOMY. 



2G4. The Dorsal Interossei. 

 Left Foot. 



f 



Fig. 265. The Plantar Intorossei. 

 Left Foot. 



Nerves. The Flexor Brevis Pollicis is supplied 

 by the internal plantar nerve, and sometimes 

 (according to Meckel) receives a branch from the 

 external plantar. The other three muscles of 

 this layer are supplied by the external plantar 

 nerve. 



Relations. By its under surface, with the ten- 

 dons of the long and short Flexors and Lumbri- 

 cales. By its upper surface, with the Interossei. 



Fourth Layer. 

 The Interossei. 



The Interossei muscles in the foot are similar 

 to those in the hand, with this exception, that 

 they are grouped around the middle line of the 

 second toe, instead of the middle line of the whole 

 member, as in the hand. They are seven in num- 

 ber, and consist of two groups, dorsal and plantar. 



The Dorsal Interossei, four in number, are situ- 

 ated between the metatarsal bones. They are 

 bipenniform muscles, arising by two heads from 

 the adjacent sides of the metatarsal bones between 

 which they are placed; their tendons are inserted 

 into the bases of the first phalanges, and into the 

 aponeurosis of the common extensor tendon. In 

 the angular interval left between each muscle at 

 its posterior extremity, the perforating arteries 

 pass to the dorsum of the foot ; except in the first 

 Interosseous muscle, where the interval allows 

 the passage of the communicating branch of the 

 dorsalis pedis artery. The first Dorsal Interos- 

 seous muscle is inserted into the inner side of the 

 second toe ; the other three are inserted into the 

 outer sides of the second, third, and fourth toes. 

 They are all adductors from the middle line of 

 the second toe. 



The Plantar Interossei, three in number, lie be- 

 neath, rather than between, the metatarsal bones. 

 They are single muscles, and are each connected 

 with but one metatarsal bone. They arise from 

 the base and inner sides of the shaft, of the third, 

 fourth, and fifth metatarsal bones, and are inserted 

 into the inner sides of the bases of the first pha- 

 langes of the same toes, and into the aponeurosis 

 of the common extensor tendon. These muscles 

 are all adductors towards the middle line of the 

 second toe. 



All the Interossei muscles are supplied by the 

 external plantar nerve. 



SURGICAL ANATOMY. 



The student should now consider the. effects produced by the action of the various muscles in 

 fractures of the bones of the lower extremity. The more common forms of fracture are selected 

 for illustration and description. 



