PLATE XXXV. 

 THE SECOND LAYER OF MUSCLES IN THE SOLE. 



In this dissection the flexor brevis digitoruin has been cut away close to its origin 

 from the os calcis, and the tendons severed from the belly of the muscle and turned 

 forwards ; the abductor minimi digiti has been turned outwards after being cut away 

 from its origin ; and the origin of the abductor hallucis partially severed, to show more 

 completely the structures which enter the sole of the foot under cover of its origin from 

 the internal annular ligament. 



The large origin of the abductor minimi digiti from both tubercles of the os calcis 

 and the space of bone between them, compared with the small pointed origin of the 

 flexor brevis digitorum from the inner tubercle, is well shown. 



The fibrous band marked S is called the ligament of the fifth metatarsal, and 

 occupies the position of Wood's muscle, of which it is a fibrous retrogression. 

 The second layer of muscles in the sole comprises 



1. Flexor accessorius. 



2. Tendon of flexor longus digitorum and lumbricalea. 



3. Tendon of flexor longus hallucis. 



The tendon of the flexor longus hallucis is connected with the upper surface of the 

 flexor longus digitorum, as they cross the sole, by a strong fibrous slip, which is chiefly 

 traceable into the tendons of the second and third toes. In dealing with the back of the 

 leg it was pointed out that the flexor fibularis (flexor longus hallucis) is very constant in 

 mammals, and in most is of far greater importance as a flexor of the digits than the flexor 

 tibialis (flexor longus digitorum). In a great number of instances it sends slips to all 

 the toes, especially those which are functionally the most powerful ; while, with the 

 exception of the bat tribe, the tibialis is a much weaker muscle. In other cases both 

 tendons join, and conjointly form the perforating tendons of the toes. Hence the slip 

 which connects the flexor longus hallucis with the flexor longus digitorum is really the 

 remains of its insertion into the other toes. Conversely the flexor digitorum sometimes 

 sends a slip to the hallucis, but it is very rare to find the two tendons entirely separate : 

 this last arrangement is one which belongs chiefly to the lower mammalian orders. 



The flexor accessorius is nothing more than a tarsal slip of the long flexors ; it is 

 extremely useful in correcting the otherwise oblique pull of the long flexor, the resultant 

 of the two being a nearly direct pull backwards upon the digits. 



The nerve supply to the lumbricales is given in most textbooks as the two inner 

 from the internal plantar, the two external from the external plantar, but more usually 

 the three external are supplied by the external plantar, and only the inner by the 

 internal, showing that possibly on account of pressure the nerve supply is removing to 

 the deep surface of the muscle. (St. John Brooks.) 



