PUDENDAL PLEXUS. 



735 



and laterally in the sole^ in company with the lateral plantar artery, between 

 the flexor digitorum brevis and the quadratus plantse, towards the base of the 

 fifth metatarsal bone. There it terminates by dividing 

 into superficial and deep branches. 



Collateral Branches. Muscular branches are given off 

 from the undivided nerve to the quadratus plantse and 

 abductor digiti quinti muscles. Cutaneous branches pierce 

 the plantar fascia at intervals along the line of the inter- 

 muscular septum, between the flexor digitorum brevis and 

 abductor digiti quinti. 



Terminal Branches Ramus Superficialis. The super- 

 ficial branch is mainly cutaneous. Passing forwards be- 

 tween the flexor digitorum brevis and abductor digiti 

 quinti, it divides into lateral and medial parts. 



The- lateral branch, after supplying the flexor quinti 

 digiti brevis muscle, and sometimes one or both interossei 

 of the fourth space, becomes superficial behind the ball 

 of the little toe, and supplies cutaneous twigs to the sole of 

 the foot and ball of the toe. It terminates as the proper 

 digital branch for the lateral side of the little toe. 



The medial branch passes forwards to the interval 

 between the fourth and fifth toes, where it becomes 

 cutaneous, and divides into two proper digital branches 

 for the supply of the adjacent sides of these toes. It 

 communicates with the fourth terminal branch of the FlG - 630. SCHEME OF DISTRI- 



j- 1 T BUTION OP THE PLANTAR 



medial plantar nerve. NERVES 



Ramus Profundus. The deep branch of the lateral In brown ^ medial plantar nerve> 

 plantar nerve, passing deeply along with the lateral and its cutaneous and mus- 

 plantar artery, extends medially towards the great toe, 

 under cover of (i.e. dorsal to) the quadratus plantse and 

 oblique head of the adductor hallucis. It gives off 

 articular branches to the tarsal and tarso-metatarsal joints, 

 and muscular branches to the interossei of each space 

 (except in some cases the muscles of the fourth space) : 

 to the adductor hallucis, and the lateral three lumbrical 

 muscles. These nerves enter the deep surface of the 

 muscles, that to the second lumbrical reaching its muscle 

 after passing forwards dorsal to, the transverse head of the adductor hallucis. 



cular branches ; F.B.D, 

 Flexor digitorum brevis; A.H, 

 Abductor hallucis ; F.B.H, 

 Flexor hallucis brevis ; L.I, 

 First lumbrical. In green, 

 lateral plantar nerve, and its 

 cutaneous and muscular 

 branches ; Quad. P, Quadratus 

 plantse ; A.D.Q, Abductor 

 digiti quinti; F.B.D.Q, Flexor 

 brevis digiti quinti. 



, 



PLEXUS PUDENDUS. 



The pudendal plexus constitutes the third and last subdivision of the lumbo- 

 sacral plexus. It is composed, for the most part, of the spinal nerves below 

 those which form the sacral plexus; but, as already stated, there is no distinct 

 point of separation between the two plexuses. On the contrary, there is con- 

 siderable overlapping, so that two and sometimes three of the principal nerves 

 derived from the pudendal plexus have their origin in common with nerves of the 

 sacral plexus. 



The plexus is formed by fibres from the anterior rami of the first three 

 sacral nerves, and by the whole of the anterior rami of the fourth and fifth sacral 

 ( and coccygeal nerves. The size of the nerves diminishes rapidly from the first 

 sacral to the coccygeal, which is extremely slender. 



Position and Constitution. The plexus is formed on the posterior wall of 

 the pelvis. Of the nerves forming it, the upper ones emerge from the anterior 

 sacral foramina ; the fifth sacral nerve appears between the last sacral and first 

 coccygeal vertebra; and the coccygeal nerve appears below the transverse pro- 

 cess of that vertebra. The nerves of distribution derived from the plexus are the 

 following : 



