MUSCULAR SYSTEM OF THE RED HOWLING MONKEY 159 



asserts that they do not exist in Brachyteles. Only Glaesmer (1910) 

 attributes an origin to the soleus in Ateles variegatus {=Ateles bel- 

 zebuth) from the upper third of the fibula. In this animal the distri- 

 bution of tendons of the flexor tibialis and peroneus seems to differ 

 from what Straus (1949) has indicated to be a typical platyrrhine 

 pattern and which I have confirmed in the howler. Its flexor fibularis, 

 together ^^'ith the tibiahs, forms the long tendon to toes I, II, and 



IV, and supphes all of that for the third; the tibiahs contributes 

 to the perforating tendons of toes I, II, and IV, and supplies the 

 whole of that to V (Glaesmer, 1910). In Ateles ater {= Ateles paniscus) 

 the tibialis forms the tendon to V and contributes to that of the 

 fourth together ^\-ith the flexor fibularis which also suppUes tendons 

 for toes I, II, and III (Glaesmer, 1910). The flexor tibiahs of Cebus 

 "monachus" provides the tendon to V and Avith the fibularis con- 

 tributes to that of the hallux. The other toes receive their long tendons 

 from the peroneal flexor (Glaesmer, 1910). The flexor fibularis and 

 the tibiahs of the woolly spider monkey (Hill, 1962) also depart 

 from Straus' pattern (see Straus, 1949). In this animal the first 

 supphes the tendon to the hallux together Avith a contribution from 

 the fibularis. In addition, it forms the long tendons to toes IV and 



V. The fibularis, on the other hand, is responsible for those to the 

 II and III. All the authors concerned agree on the presence of a 

 plantaris only in Cebus and of m. quadratus plantae in aU the 

 genera. 



Pedal Group 



SUPERFICIAL SERIES, SUPERFICIAL LAYER 



M. abductor hallucis: This powerful and long muscle arises by 

 fleshy fibers from the medially projecting calcaneal tubercle (there is 

 no lateral tubercle) and from the outer surface of the tibial flexor 

 retinaculum as this passes toward the tibial malleolus (fig. 48). The 

 belly thus formed runs distally along the medial canal of the calcaneus, 

 where it covers the tendons, vessels, and nerves which enter the foot 

 from the dorsum of the leg. The tibial edge of the plantar aponeurosis 

 provides for the origin of more fleshy fibers. An additional group of 

 tendinous elements reaches the peroneal side of the muscle at the 

 level of the naviculocuneiform joint. These fibers have a common 

 origin with those of the flexor hallucis brevis, caput tibialis, from the 

 [)lantar aspect of the second cuneiform. Insertion takes place over a 

 long tendon which begins in the center of the muscle opposite the first 

 cuneiform. The tendon is separated from the first metatarsal by the 

 tibial head of m. flexor hallucis brevis. Final insertion is on the tibial 

 base of the first hallucal phalanx after establishing a firm connection 

 w ith the underlying metatarsophalangeal joint capsule. 



