OSTEOLOGY. 71 



fourth phalanx, and has four muscular attachments for ad- 

 ductor poilicis, third and fourth dorsal, and second plantar 

 interossei. 



The fifth has marked tubercle on outer side. It articulates 

 with cuboid, fourth metatarsal, and fifth phalanx, and has five 

 muscular attachments for flexor brevis minimi digiti, peroneus 

 brevis and tertius, fourth dorsal, and third plantar interosseus. 



THE PHALANGES have same general characteristics as in 

 hand, but are compressed from side to side instead of from before 

 backward. The muscular insertions to first row are to great 

 toe, transversus pedis, extensor brevis digitorum, adductor, ab- 

 ductor, and flexor brevis poilicis ; to second, first and second dor- 

 sal interosseus; to third, third dorsal and first plantar inter- 

 osseus; to fourth, fourth dorsal and second plantar interosseus; 

 to fifth, abductor and flexor brevis minimi digiti and third 

 plantar interosseus. To second row to great toe, flexor and 

 extensor longus poilicis; to remaining toes, extensor longus and 

 brevis digitorum, flexor brevis digitorum, and lumbricales. To 

 third row, or ungual phalanges flexor longus. and extensor 

 longus and brevis digitorum. 



The ossific centres are one each for the tarsus, excepting the 

 os calcis, which has an epiphysis for posterior part, and two each 

 for metatarsals and phalanges. These latter are arranged in 

 phalanges, one each for shaft and base, and in metatarsals, one 

 each for shaft and head, excepting great one, which has one each 

 for shaft and base. 



SESAMOID BONES are small, osseous masses, cartilaginous in 

 early life, developed in the tendons to relieve pressure. They are 

 of two kinds those over articular surfaces of joints, as patella; 

 and those applied to the surfaces of bones, as in tendon of pero- 

 neus longus in the groove of cuboid bone. 



