C21 - Plexus lumbalis

Question 1

Define plexus lumbalis

Answer 1

• Plexus lumbalis + plexus sacralis = plexus lumbosacralis
• Supplies:
  • Cranial and medial muscles of the thigh
  • Skin of medial aspect of the thigh
  • Tarsus
  • Metatarsus

Question 2

Which spinal nerves gives rise to the lumbar plexus?

Answer 2

• The number of lumbar neves corresponds with the number of lumbar vertebrae:
  
  • Eq, su, ru: 6
  • Car: 7
• Divide into dorsal and ventral branches after their passage through for. intervertebrale
  
  • ​Dorsal branches divides into:
    
    • R. medialis
    • R. lateralis
  • Ventral branches of the lumbar spinal nerves forms the lumbar plexus

Question 3

Which nerves arise from the lumbar plexus?

Answer 3

Species with 7 lumbar vertebrae (car):

1. N. iliohypogasticus cranialis (L1)
2. N. iliohypogasticus caudalis (L2)
3. ​N. ilioinguinalis (L2)
4. N. genitofemoralis (L3, L4)
5. N. cutaneous femoris lateralis (L4)
6. N. femoralis (L4, L5, L6)
   
   • N. saphena (N. femoralis)
7. N. obturatorius (L4, L5, L6)

Species with 6 lumbar vertebrae (eq, ru, su):

1. N. iliohypogasticus
2. ​N. ilioinguinalis (L2)
3. N. genitofemoralis (L3, L4)
4. N. cutaneous femoris lateralis (L4)
5. N. femoralis (L4, L5, L6)
   
   • N. saphena (N. femoralis)
6. N. obturatorius (L4, L5, L6)

Question 4

List the:

1. Name of the nerve
2. Origin
3. Innervation

Answer 4

Question 5

Draw plexus lumbosacralis

Answer 5

Question 6

N. iliohypogastricus

Answer 6

• Emerges from for. intervertebrale and divides into (?):
  
  • R. lateralis
  • R. medialis
• In car with 7 lumbar vertebrae:
  
  • N. iliohypogastricus cranialis
  • N. iliohypogastricus caudalis

Question 7

N. ilioinguinalis

Answer 7

Same distribution as n. iliohypogastricus

Question 8

N. genitofemoralis

Answer 8

• Divides into:
  
  • R. genitalis
    
    • ​Runs thorugh canalis inguinalis
    • Innervates in female:
      
      • Mammary complex
      • Vulva
    • ​Innervates in males:
      
      • Scrotum/testis
      • Fascia spermatica
      • M. cremaster
      • Prepuce
  • R. femoralis

Question 9

N. femoralis

Answer 9

• Ramus ventralis of L3-L6
• Thickest nerve of plexus lumbalis

Divides into:

• Rr. musculares
  
  • ​Innervates:
    
    • Mm. iliopsoas
    • M. posas minor
    • M. quadriceps femoris
    • M. sartorius
    • M. pectineus
• N. saphenus
  
  • ​Rr. musculares
    
    • ​Innervates:
      
      • M. sartorius
      • M. quadriceps femoris
  • Rr. cutanei
    
    • ​Innervates: skin of medial aspect of crus, tarsu and metatarsus

Question 10

N. obturatorius

Answer 10

• Ramus ventralis of L4-L6
• Only motor fibers

Divides into:

• R. cranialis
  
  • ​Innervates adductors of the tight:
    
    • M. gracilis
    • M. pectineus
    • M. adductor
• R. caudalis
  
  • ​Innervates:
    
    • Adductor muscles
    • M. obturatorius externus
    • Ru, su: m. obturatorius internus