254 MUSCLES OF THE LOWER LIMB. 



the under snrfiico of the sustentaculnm tali, being bound down to those 

 bones by fibrous and synovial sheaths. Thence passing forwards and 

 inwards, in the sole of the foot, it gives off" a tendinous slip to the 

 tendon of the flexor longus digitorum, by wliich it is crossed, and 

 proceeds in a fibrous sheath over the first phalanx of the great toe 

 to be inserted into the base of the terminal phalanx. 



Bdaf'wmt. — This nuigcle is concealed for the most jiart hy tlie soleus, a small 

 part only at the outer side of the tendo Achillis being- covered by the fascia of the 

 leg-. Externally it is in contact with the peronei, and internally with the tibialis 

 posticus. It rests upon the fibula and conceals the jieroneal vessels. Below the 

 ankle the tendon of this muscle is separated from that of the flexor longus digi- 

 torum by an interval of more than half an inch, in Avhich are placed the pos- 

 terior tibial vessels and nei-ves. In the sole it is covered by the ijlantar fascia 

 and abductor iDollicis muscle ; it is also crossed by the plantar vessels and nen^es, 

 and the tendon of the long flexor of the toes. It rests upon the flexor brevis 

 pollicis. 



Varh't'ie.<>. — This muscle is liable to very few variations, biit the mode of imion 

 of its tendon with that of the flexor longus digitorum is exceedingly variable. 

 According to Timier, in no two subjects is it exactly similar. In almost every 

 case the slip of union comes from the flexor pollicis. though in about one-sixth of 

 the cases an additional slip proceeds from the flexor digitomm to the flexor pollicis 

 (Tui'ner, ^\'ood). Comiilete separation of the tendons is very rare. This slip from 

 the flexor pollicis most frequently passes to the second and tliii-d toes but it may 

 jiass to the second only, or to all the four outer toes. 



The iwronvo-calcaacux intcrnuH is a small muscle described by Macalister as the 

 probable homotype of the pronator quadi-atus of the arm. It arises below the 

 flexor longus pollicis from an oblique line on the back of the fibula, behind the 

 external malleolus, passes over the sustentaculmn tali in the groove with the 

 flexor pollicis, to be inserted into a tubercle of the os calcis (Muscular Anomalies, 

 p. 125). 



Fig. 197. — Transverse Section of tiik Eight 

 Foot between the Tars'js and Metatarsus. 

 A. T. 4 



«, h, c, articular metatarsal surface of the internal, 

 middle, and external cuneiform bones ; d and e, the 

 surfaces of the cuboid boue for the fourth and fifth 

 metatarsal bones ; between these bones arc seen the 

 strong interosseous and plantar ligaments which 

 bind them together; ], slip of the tendon of the 

 tiljialis anticns, wliich passes on to its insertion on 

 te. ^- a ^ ^^M/ ^'^^ ^^'^^ metatarsal boue ; 2, tendon of the extensor 



^v^^-^_f _ ^:;i=^^^^ longus pollicis ; 3, slip of the extensor brevis digi- 



torum to the great toe ; 3', remainder of the ex- 

 tensor brevis digitorum ; 4, foiu* slips of the ex- 

 tensor communis digitorum longus ; 5, peroneus 

 tertius ; 6, peroneus brevis ; 7, peroneus longus cut obliiiucly where it is emerging from 

 its sheath below the cuboid Ijone ; 8, tendon of tlie flexor longus pollicis ; 9, tendon of 

 the flexor communis digitorum longus, with the sM-p of union from the flexor pollicis ; 

 10, flexor accessorius ; 11, abductor pollicis ; 12, flexor brevis digitorum ; 13, abductor 

 minimi digiti. 



The tibialis posticus muscle, placed between the two long flexor 

 muscles, arises from the whole interosseous membrane except for two 

 inches at the lower end, and from the adjacent surfaces of the tibia and 

 fibula, the tibial attachment extending from the superior tiliio-fibular 

 articulation to a point at a lower level than that of the flexor longus 

 digitorum, and the attachment to the fibula extending along the three 

 middle fifths of that bone ; it also arises from the aponeurosis derived 



