MUSCLES OF THE PELVIC LIMBS. 215 



The interossei of the third and fourth digits are ahke. 



Origin from the ventral surface of the base of the metatar- 

 sal. The muscles cover the ventral surface of the shaft. At 

 the head eacli divides and passes onto the sides of the 

 metatarsal. 



Insertion. — Each half of the muscle shows a tendency to 

 divide into two parts. One of these, the more superficial and 

 ventral, ends In a tendon which joins the extensor tendon near 

 the distal end of the first phalanx. The other part is inserted 

 by short tendon- and muscle-fibres into the side of the base of 

 the first phalanx ; one of the parts is therefore a middle, and the 

 other a long, adductor or abductor, the adductores and abduc- 

 tores digiti tertii and quarti. 



The fifth digit has five short muscles. 



M. abductor medius digiti quinti. 



Origin from the ventral surface of the calcaneus and from 

 the fifth metatarsal. 



Insertion by a slender tendon into the lateral side of the 

 base of the first phalanx of the fifth digit. 



M. adductor medius digiti quinti. 



Origin with the adductor medius digiti secundi. 



Insertion on the inner side of the base of the phalanx of the 

 fifth digit. 



M. opponens digiti quinti. 



Origin by a flat tendon from the middle of the ligament 

 which covers the peroneal canal. It passes obliquely outward 

 parallel to the last. 



Insertion on the inner side of the shaft of the fifth metatar- 

 sal. 



The two remaining muscles of the fifth digit take origin 

 from the outer part of the ligament covering the peroneal canal. 

 They cover the ventral surface of the shaft. 



Insertion. — The lateral one is inserted into the lateral sesa- 

 moid and is therefore an abductor brevis. The medial one is 

 inserted into the extensor tendon and is therefore an adductor 

 longus. 



C. Muscles of the Tarsus. — M. calcaneometatarsalis 

 (part of M. adductor minimi digiti .''). — A weak muscle made up 



