THE SACRAL PLEXUS.

The femoral cutaneous branches (descending) are numerous filaments, derived from both sides of the nerves, which are distributed to the back, inner, and outer sides of the thigh, to the skin covering the popliteal space, and to the upper part
of the leg.
The Perforating Cutaneous Nerve usually arises from the second and third sacral
nerves, and is of small size. It is continued backward through the great sacro¬sciatic ligament, and, winding round the lower border of the Gluteus maximus, supplies the integument covering the inner and lower part of that muscle.
The Pudic Nerve is the direct continuation of the lower cord of the sacral plexus, and derives its fibres from the third and fourth sacral nerves,and frequently from the second also. It leaves the pelvis through the great sacro-sciatic foramen, below the Pyriformis. It then crosses the spine of the ischium, and re-enters the pelvis through the lesser sacro-sciatic foramen. It accompanies the pudic vessels upward and forward along the outer wall of the ischio-rectal fossa, being contained in a sheath of the obturator fascia, termed Alcoclc's canal, and divides into two terminal branches. the perineal nerve and the dorsal nerve of the penis or clitoris. Before its division it gi ves off the inferior hemorrhoidal nerve.
The inferior hemorrhoidal nerve is occnsionally derived separately from the sacral plexus. It passes across the iscbio-rectal fossa, with its accompanying vessels, toward the lower end of the rectum, and is distributed to the Sphincter ani externus and to the integument round the anus. Branches of this nerve com¬municate with the inferior pudendal and superficial perineal nerves at the fore part
of the perineum.
The perineal nerve, the inferior and larger of the two terminal branches of the
pudic, is situated below the pudic artery. It accompanies the superficial perineal artery in the perineum, dividing into cutaneous and muscular branches.