nervy nerves Flashcards
Where is the Lumbar Plexus formed?
within the belly of the psoas major muscle
In which directions do the Lumbar plexus branches exit from psoas major?
3 (lateral, anterior, medial)
What spinal nerves form the lumbar plexus?
- ventral rami of L1-L4 spinal nerves
L5 ventral ramus contributes to one of the branches of this plexus, but is not technically included in the formation of the plexus
Which branches of the lumbar plexus exit the psoas major laterally?
Iliohypogastric nerve (L1)
Ilioinguinal nerve (L1)
Lateral Cutaneous nerve of the thigh (L2, 3)
Femoral nerve (L2, 3, 4)
Which branches of the lumbar plexus exit the psoas major anteriorly?
Genitofemoral nerve (L1, 2)
Which branches of the lumbar plexus exit the psoas major medially?
Obturator nerve (L2, 3, 4)
Accessory Obturator nerve (L3, 4) - when present
Lumbosacral Trunk (L4, 5)
What does the Iliohypogastric nerve (L1) supply?
- skin of the suprapubic region
- also gives motor supply to abdominal muscles
What does the Ilioinguinal nerve (L1) supply?
- skin of the inguinal region
- also gives motor supply to abdominal muscles
What does the lateral cutaneous nerve of the thigh (L2, 3) supply?
supplied the skin of lateral thigh
What does the lateral cutaneous nerve of the thigh (L2, 3) pass?
- inferolaterally over iliacus
- posterior to the inguinal ligament
What name is the lateral cutaneous nerve of the thigh (l2, 3) also known by?
lateral femoral cutaneous nerve
What does the femoral nerve (L2, 3, 4) pass?
- passes deep to the inguinal ligament into the anterior thigh
What does the femoral nerve (L2, 3, 4) supply?
- cutaneous supply to anterior thigh, then skin of medial leg via its terminal branch the saphenous nerve
- supplies most of anterior thigh muscles (flexors of hip & extensors of knee)
In what branches does the Genitofemoral nerve (L1/2) divide into?
genital branch
femoral branch
What does the genital branch supply?
- supplies skin of scrotum in males & labia majora in females
What does the femoral branch supply?
- supplies skin over the anterosuperior thigh
What does the Obturator nerve (L2-4) pass?
passes through the pelvis & through obturator foramen to the medial thigh
What does the Obturator nerve (L2-4) supply?
- most of the medial thigh muscles
- cutaneous supply of medial thigh
What does the Accessory Obturator nerve (L3, 4) supply?
supplies the hip joint
What does the Lumbosacral trunk (L4, L5) pass?
over the ala of sacrum to enter pelvis
What is the Sacral Plexus formed by?
ventral rami of L4 - S4 (L4, L5 are via lumbosacral trunk)
When describing the location of the sacral plexus, where is it located/formed?
- located on posterolateral wall of pelvis
- formed anterior to piriformis
How many nerves are formed within the sacral plexus?
11 - only need to learn about 7
Sciatic nerve - spinal levels
L4-S3
Tibial division of sciatic nerve (L4-S3)
Common fibular division of sciatic nerve (L4-S2)
Sciatic nerve - facts
- largest nerve in the body
- exits the pelvis through the greater sciatic foramen, below piriformis
- has two divisions held together in a common sheath (later divides into two separate nerves)
Sciatic nerve supply
Cutaneous - none
Motor - tibial division supplies semimembranosus, semitendinosus, long head of biceps femoris and hamstring part of add magnus; common fibular division supplies short head of biceps femoris
Sacral Plexus Branches
Nerve to piriformis (S1, S2)
Nerve to obturator internus (L5-S2)
Nerve to quadratus femoris (L4-S1)
Superior gluteal nerve (L4-S1)
Inferior gluteal nerve (L5-S2)
Perforating cutaneous nerve (S2/3)
Posterior cutaneous nerve of thigh (S2/3)
Pudenal nerve (S2-S4)
Nerve to levator ani & coccygeus (S3, S4)
Pelvic splanchnic nerves (S2-S4)
What does Nerve to piriformis (S1, S2) supply?
piriformis
What does Nerve to obturator internus (L5-S2) supply?
obturator internus & superior gemellus
What does Nerve to quadratus femoris (L4-S1) supply?
quadratus femoris & inferior gemellus
What does Superior gluteal nerve (L4-S1) supply and pass through?
supplies - glute med, min and TFL
passes through GSF superior to piriformis
What does Inferior gluteal nerve (L5-S2) supply and pass through?
supplies - glute max
passes through GSF inferior to piriformis
What does Perforating cutaneous nerve (S2/3) supply?
skin over medial aspect of buttocks
What does Posterior cutaneous nerve of thigh (S2/3) supply and pass through?
supplies - skin ove rlower buttock, uppermost medial and posterior surfaces of the thigh
passes through GSF inferior to piriformis
Myotomes - L1/L2
hip flexion
Myotomes - L3/L4
knee extension
Myotomes - L4/L5
knee flexion OR ankle dorsiflexion
Myotomes - L5
Hallux extension
Myotomes - S1/S2
Ankle plantarflexion
