240 FIBULAE REGION. 



longus digitorum, tibialis posticus, flexor longus pollicis. At the 

 inner malleolus, the relation of the tendons is tibialis posticus, 

 flexor longus digitorum, both in the same sheath ; then a broad 

 groove, which lodges the posterior tibial artery, venae comites, and 

 nerve ; and lastly, the flexor longus pollicis. 



Actions. The popliteus is a flexor of the tibia upon the thigh, 

 carrying it at the same time inwards so as to invert the leg. The 

 flexor longus pollicis, and flexor longus digitorum are the long 

 flexors of the toes ; their tendons are connected in the foot by a 

 short tendinous band, hence they necessarily act together. The 

 tibialis posticus is an extensor of the tarsus upon the leg, and an 

 antagonist to the tibialis anticus. It combines with the tibalis anticus 

 in adduction of the foot. 



Fibular Region. 



Peroneus longus, 

 Peroneus brevis. 



Dissection. These muscles are exposed by continuing the dissec- 

 tion of the anterior tibial region outwards beyond the fibula, to the 

 border of the posterior tibial region. 



The Peroneus longus (irego'vr), fibula, extensor tarsi fibularis longior) 

 muscle arises from the upper third of the outer side of the fibula, 

 and terminates in a long tendon, which passes behind the external 

 malleolus, and obliquely across the sole of the foot, through the 

 groove in the cuboid bone, to be inserted into the base of the meta- 

 tarsal bone of the great toe. Its tendon is thickened when it glides 

 behind the external malleolus, and a sesamoid bone is developed in 

 that part which plays upon the cuboid bone. 



Relations. By its superficial surface with the fascia of the leg 

 and foot. By its deep surface with me fibula, peroneus brevis, os 

 calcis, and cuboid bone, and near the head of the fibula with the 

 fibular nerve. By its anterior border it is separated from the extensor 

 longus digitorum by thfe attachment of the fascia of the leg to the 

 fibula ; and by the posterior border by the same medium from the 

 soleus and flexor longus pollicis. The peroneus longus is furnished 

 with three tendinous sheaths and as many synovial membranes ; the 

 first is situated behind the external malleolus, and is common to this 

 muscle and the peroneus brevis, the second on the outer side of the 

 os calcis, and the third on the cuboid bone. 



The Peroneus brevis (extensor tarsi fibularis brevior) lies beneath 

 the peroneus longus ; it arises from the lower two-thirds of the fibula, 

 and terminates in a tendon which passes behind the external mal- 

 leolus and through a groove in the os calcis, to be inserted into the 

 base of the metatarsal bone of the little toe. 



Relations. By its superficial surface with the peroneus longus 

 and fascia of the leg and foot. By its deep surface with the fibula, 

 the os calcis, and cuboid bone. The lateral relations are the same 

 as those of the peroneus longus. The tendon of the peroneus brevis 



