Nerve supply

  
  • Derived from sacral and coccygeal spinal neres

  • Pelvic part of autonomic nervous system

  • Each of the five sacral nerves divides into a dorsal and ventral ramus within the sacral canal

  • The dorsal rami of the first four sacral nerves pass backward through the dorsal sacral foramina.

  • Those of the fifth sacral and coccygeal  emerge from the sacral canal through the sacral hiatus

  • The ventral rami of the first four sacral nerves emerge from the sacral canal through the pelvic sacral foramina.

  • The third and fourth sacral and occassionaly the second or fifth also, give off the pelvic splanchnic nerves which help form the autonomic plexus within the pelvis.

Sacral plexus

  
  • Formed by the ventral rami of the fourth and fifth lumbar and first four sacral nervers.

  • Ventral ramus of the fourth lumbar divides into upper ad lower parts.

  • The lower division joins the ventral ramus of the fifth lumbar  nerve to form the lumbosacral trunk

  • The lumbosacral trunk descends and joins the ventral ramus of the fourth sacral also has upper and lower divisions.

  • Its upper part joins the third sacral, its lower part the fifth sacral.

  • With the exception of the fourth sacral, each ventral ramus first divides inot ventral and dorsal branches before entering into the formation of the sacral plexus.
Relations  
  • Lies infront of piriformis

  • Separated from the internal iliac vessels and ureters anterioly by the parietal pelvic fascia

  • Superior gluteal vessels pass between the lumbosacral trunk and the ventral branches of the first and second or second and third sacral nerves

  • The internal pudendal vessels run between the sciatic and pudendal nerves.

Distribution

  
  • The sacral plexus had twelve branches.

  • Seven of these supply the buttock and  lower limb, the rest supply structures belonging to the pelvis.
    These are.
Nerve
Root value
Course and Distribution
Buttock and Lower Limb
     
Superior gluteal nerve
L4,5,S1
  • Accompanies superior gluteal vessels into the buttocks where it is distributed
Inferior gluteal nerve
L5, S1, 2
  • Supplies gluteus maximus
Nerve to quadratus femoris
L4,5,S1
  • Supplies inferior gamellus

  • quadratus femoris

  • Hip jointy
Nerve to obturator internus
L5, S1, 2
  • Superior gamellus

  • Obturator internus
Posterior femoral cutaneous
S1,2,3
  • Cutaneous
Perforating cutaneous |
S2, S3
  • Skin

  • Subcutaneous tissue of the lower part of buttock
Sciatic nerve
L4, 5, S1, 2, 3
  • The largest in the body

  • Peroneal and tibial bound together

  • Leaves pelvis through greater sciatic foramen
     
Pelvis    
Nerve to piriformis S1, S2
  • Piriformis muscle
Nerve to levator ani and coccygeus S3, 4
  • Levator ani

  • Coccygeys
Nerve to sphincter ani externus S4
  • sphincter ani externus as well as the surrounding and subcutaneous tissue
Pelvic splanchnic nerves
S2, 3,4,5
  • Contain parasympathetic preganglionic and sensory fibres

  • Supply sigmoid colion
Pudendal nerve s2, 3,4
  • Furnishes most of the perineum.

  • It has motor and sensory fibres post ganglionic sympathetic fibres
 

COCYGEAL PLEXUS

  
  • Formed by  ventral rami of the fifth sacral and the coccygeal nerve which  join the lower division of the ventral ramus of the fourth sacral

  • It supplies  the sacrococcygeal joint, the coccyx, and the skin the coccyx.

PELVIC PART OF AUTONOMIC NERVOUS SYSTEM

The symphathetic part of the autonomic nervous system reaches the pelvis by two different routes.

    • The downward continuation of the sympathetic trunk, and
    • The downward continuation of the aortic plexus