D28 - N. pudendus and n. ischiadicus down to the stifle joint

Question 1

Give the sciatic plexus

Answer 1

• The sciatic plexus is an extension of the lumbosacral plexus, and continues as n. sciaticus
• N. sciaticus leaves the pelvis through greater sciatic foramen
• Proximal at femur, it divides into:
  
  • N. peroneus communis
    
    • Detatches n. cutaneus surae lateralis
    • Divides into:
      
      • ​N. peroneus superficialis
      • N. peroneus profundus
  • N. tibialis
    
    • ​Detatches n. cutaneus surae caudalis
    • Terminal division:
      
      • N. plantaris medialis
      • N. plantaris lateralis

Question 2

Draw n. ischiadicus

Answer 2

Question 3

N. pudendus

Answer 3

• Arises from the S3
• Sends communicating brances to n. femoralis cutaneous caudalis
• Males: continues as n. perinealis dorsalis (to innervate glans penis)
• Females: terminates in the vulva

Innervation

• Motor:
  
  • Copulatory organs
  • Muscles:
    
    • Anal sphincters
    • M. ischiocavernous
    • M. bulbospongiosus
    • M. retractor penis
    • M. urethralis
    • M. constrictor vulvae
    • M. coccygeus
    • M. levator ani
• Sensory: Skin around anus and perineal region
• Parasympathetic: pelvic viscera through pelvic plexus (joined by sympathetic fibers from n. hypogastricus and n. sacralis splanchnicus)

Question 4

Define plexus sacralis

General knowledge

Answer 4

• Plexus lumbalis + plexus sacralis = plexus lumbosacralis
  
  • Ventral branches of the cranial sacral nerves form plexus sacralis, whixh joins the ventral branches of the last three lubar spinal nerves to form plexus lumbosacralis
• Plexus sacralis extends distally in the wall of the pelvic cavity as the sciatic plexus. It gives origin to:
  
  • N. gluteus cranialis
  • N. gluteus caudalis
  • N. cutaneous femoris caudalis
  • N. pudendus
  • N. rectalis caudalis
• The sciatic plexus continues as n. sciaticus after the detachment of these branches
• Supplies:
  
  • Caudal muscles of the thigh
  • Skin

Question 5

Give the sacral part of the lumbosacral plexus

General knowledge

Answer 5

• The sacral part of the lumbosacral plexus extends distally in the wall of the pelvic cavity
• They have 2 main destinations:
  
  • Leaves the pelvis via for. sciaticus major
  • Remain in the pelvis

Question 6

Draw plexus lumbosacralis

Answer 6