268 



POSTERIOR TIBIAL REGION. DEEP LAYER. 



Fig. 108.* 



and nerve. By its deep surface with the tibia and tibialis posticus. 

 In the sole of the foot its tendon is in 

 relation with the abductor pollicis and 

 flexor brevis digitorum, which lie super- 

 ficially to it, and it crosses the tendon 

 of the flexor longus pollicis. At the 

 point of crossing it receives the ten- 

 dinous slip of communication from the 

 latter. 



The flexor longus pollicis must now 

 be removed from its origin, and the 

 flexor longus digitorum drawn aside, 

 to bring into view the entire extent of 

 the tibialis posticus. 



The TIBIALIS POSTICUS (extensor 

 tarsi tibialis) lies upon the interosseous 

 membrane, between the two bones of 

 the leg. It arises by two heads from 

 the adjacent sides of the tibia and 

 fibula their whole length, and from the 

 interosseous membrane. Its tendon 

 passes inwards beneath the tendon of 

 the flexor longus digitorum, and runs 

 in the same sheath ; it then passes 

 through a proper sheath over the del- 

 toid ligament, and beneath the calcaneo- 

 scaphoid articulation, to be inserted into 

 the tuberosity of the scaphoid and in- 

 ternal cuneiform bone. While in the 

 common sheath behind the internal 

 malleolus, the tendon of the tibialis 

 posticus lies internally to that of the 

 flexor longus digitorum, from which it 

 is separated by a thin fibrous partition. 

 A sesamoid bone is usually met with 

 in the tendon close to its insertion. 



Relations. By its superficial surface 

 with the intermuscular septum, the 



* The deep layer of muscles of the posterior tibial region. 1. The lower 

 extremity of the femur. 2. The ligamentum posticum Winslowii. 3. The 

 tendon of the semi-membranosus muscle dividing into its three slips. 4. The 

 internal lateral ligament of the knee-joint. 5. The external lateral ligament. 

 6. The popliteus muscle. 7. The flexor longus digitorum. 8. The tibialis pos- 

 ticus. Q. The flexor longus pollicis. 10. The peroneus longus muscle. 11. 

 The peroneus brevis. 12. The tendo Achillis divided near its insertion into the 

 os calcis. 13. The tendons of the tibialis posticus and flexor longus digitorum 

 muscles, just as they are about to pass beneath the internal annular ligament 

 of the ankle ; the interval between the latter tendon and the tendon of the 

 flexor longus pollicis is occupied by the posterior tibial vessels and nerve. 



