TERMINAL BRANCHES. 



1339 



66. The internal terminal branch (n. cutaneus dorsalis medialis) (Fig. 1117), larger than the 

 external, passes obliquely inward in front of the ankle and then forward over the dorsum of the 

 foot. Cutaneous twigs are distributed 



FIG. 1117. 



From internal 

 -cutaneous 



to the anterior aspect of the lower third 

 of the leg and the dorsum of the foot. 

 Just below the anterior annular ligament 

 the nerve breaks up into an inner, a 

 middle and an outer branch. 



The inner branch inosculates with 

 the internal saphenous nerve, from which 

 it receives an accession of fibres, and 

 passes forward to supply the integument 

 of the mesial aspect of the foot and great 

 toe. The middle branch follows the first 

 metatarsal space and inosculates with the 

 inner branch of the anterior tibial nerve. 

 The outer branch courses down the 

 second metatarsal space and divides into 

 the two dorsal digital nerves (nn. digitales 

 dorsales pedis) which supply the contig- 

 uous sides of the second and third toes. 

 This branch is sometimes derived from 

 the external terminal part of the musculo- 

 cutaneous. 



cc. The external terminal branch 

 (n. cutaneus dorsalis intermedius) (Fig. 

 1117) courses down the leg anterior to the 

 ankle and lateral to the inner branch, 

 giving off twigs to the antero-lateral por- 

 tion of the integument of the lower part 

 of the leg and dorsum of the foot. Having 

 reached the foot it breaks up into inner 

 and outer branches. 



The inner branch divides into 

 dorsal digital branches for the supply of 

 the adjacent sides of the third and fourth 

 toes, and the outer branch, after receiving 

 an accession of fibres through inoscula- 

 tion with the external saphenous, divides 

 similarly into twigs for the contiguous 

 sides of the fourth and fifth toes. The 

 dorso-lateral aspects of the terminal 

 phalanges and the nails receive addi- 

 tional filaments from the plantar nerves. 



Variations. Deficiencies in the in- 

 ternal branch are usually supplied by 

 the anterior tibial nerve and in the ex- 

 ternal by the short saphenous. In case 

 the external branch ends at the dorsum 

 of the foot, the external saphenous, which 

 would fill the vacancy at the digits, has 

 its root from the external popliteal more 

 strongly developed than usual, and thus 

 the toes are supplied in an unusual 

 manner but still by fibres from the ex- 

 ternal popliteal nerve. 



From middle 

 cutaneous 

 nerve 



From . 

 peroneal nerve 



Sural br 

 peroneal nerve 



Musculo-cuta- . 

 neons nerve 



Ext. sapl 



Ext. terminal 



br. musculo- 



cutaneous 



nerve 



From internal 



cutaneous 



nerve 



Cutaneous 

 patellar br. int. 

 saphenous 

 nerve 



Int. saphenous 

 nerve 



Crest of tibia 



Int. saphenous 

 nerve 



Int. saphenous 

 veiii 



Int. terminal 

 br. musculo- 

 cutaneous 

 nerve 



Int. terminal 

 br. ant. tibial 

 nerve 



6. THE INTERNAL POPLITEAL 

 NERVE. 



The internal popliteal or tib- 

 ial nerve (n. tibialis) (Fig. 1115) 

 is of greater size than the external 

 and corresponds in its distribution 



to the combined median and ulnar nerves of the arm. Arising from the anterior 

 portion of the sacral plexus, it includes fibres derived from the fourth and fifth lumbar 



Superficial dissection of right leg and foot, showing cutaneous 

 nerves of anterior surface. 



