CHAP. IV] THE GENERAL ANATOMY OF THE LEMUROIDEA 81 



of this muscle. The M. plantaris is large and distinct. Its tendon 

 is remarkable for extending beneath and beyond the os calcis, 

 where it widens out as the plantar fascia. The latter structure 

 and the adjacent muscles of the foot are so important as illustra- 

 tions of the arrangements in the prehensile form of that organ, 

 that a somewhat detailed description seems admissible (Fig. 43). 



(i) The plantar fascia, directly continuous as already stated 

 with the tendon of the M. plantaris, becomes wider as it is traced 

 distally, and then gives off the distinct aponeurotic band to the 

 hallux (as described by Loth, Korrespondenzblatt der Deutschen 

 Anthropologischen Gesellschaft, xxxvui. 1907), and finally con- 

 tributes feebler offshoots to the remaining digits. The M. 

 abductor hallucis receives some muscle fibres from its tibial 

 margin and " deep " aspect. The M. abductor minimi digiti, 

 arising from the os calcis, contributes a muscular fasciculus to 

 the same " deep " aspect of the plantar fascia. The narrowness 

 of the fascia and its strong offshoot to the hallux are considered to 

 stand in direct relation to the predominantly prehensile function of 

 the foot (Loth). 



(ii) The M. flexor brevis digitorum pedis arises in two ways, 

 viz. 



(a) From the deep aspect of the fascia plantaris : this portion 

 sends a " perforated " tendon to the second digit. 



(b) The second and chief origin is taken from the tendon 

 of the M. flexor digitorum longus (or flexor tibialis). This part 

 contributes the perforated tendons to the third, fourth and fifth 

 digits. Nerve fibres come from the medial plantar nerve-trunk, 

 though in some instances the lateral plantar nerve sends fibres 

 to the slip to the fifth digit 1 . 



(The hallux or first digit has thus no perforated tendon : 

 nevertheless a superficial though not a perforated tendon runs 

 to it from the tendon of the M. flexor digitorum longus.) 



(iii) The M. flexor digitorum longus has a tendon more slender 

 than that of the M. flexor hallucis longus (but stouter than the 

 tendon of the M. tibialis posticus). This tendon gives offshoots 

 to all five digits, and these offshoots (with the exception of that to 

 the hallux) perforate the tendons provided by the M. flexor brevis 

 1 Sawalischin, Morph. Jahrbuch, Band xlii. 



D. M. 6 



