_Origin_ from the ventral surface of the base of the metatarsal. The muscles cover the ventral surface of the shaft. At the head each 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 abductores 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 metatarsal. 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 sesamoid 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 largely of tendon-fibres, some of which pass directly from origin to insertion. It may be regarded as a ligament. _Origin_, the lateral and ventral surface of the calcaneus near the proximal end. It passes distad and slightly laterad outside of the quadratus plantæ. _Insertion_, the lateral side of the base of the fifth metatarsal, and the adjacent surfaces of the cuboid and calcaneus. _Action._--Probably causes slight motion of the cuboid on the head of the calcaneus. =M. scaphocuneiformis.=--A small muscle lying on the sole of the foot in the depression between the lateral cuneiform, medial cuneiform, and the lateral tubercle of the scaphoid. It is hidden by the overlying ligaments. _Origin_, the lateral tubercle of the scaphoid bone. It passes distad and laterad. _Insertion_, the lateral surface of the medial cuneiform. _Action._--Rotates the medial cuneiform on the scaphoid and would thus act as an opponens of the great toe if the great toe were present. THE VISCERA. I. THE BODY CAVITY.