University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2021
Views:

187

Pages:

27
Author:

hacedoras1kxy

Lumbar and Sacral Plexuses Structure of Spinal Nerves: Somatic Pathways dorsal ramus dorsal root spinal nerve somatic sensory nerve CNS interneuron ventral ramus ventral root Mixed Spinal Nerve somatic motor nerve Structure of Spinal Nerves: Dorsal & Ventral Rami dorsal ramus spinal nerve Territory of Dorsal Rami (everything else, but head, innervated by ventral rami) somatic sensory nerve ventral ramus somatic motor nerve Nerves of the lower limb The lumbar plexus L1-L4 Is formed by the ventral rami of the upper four lumbar nerves in the substance of psoas major muscle It also receives a contribution from T12 (subcostal) nerve 2 main nerves Femoral nerve Obturator nerve L1 L2 L3 L4 4 small nerves Ilio-hypogastric nerve Ilio-inguinal nerve Genitofemoral nerve Lateral cutaneous nerve of the thigh Ilio-hypogastric nerve Ilio-inguinal nerve L1 L2 L3 Lateral cutaneous nerve of the thigh L4 Genitofemoral nerve L5 Femoral nerve Obturator nerve Each nerve of the lumber plexus emerges (exits) from the substance of the psoas major muscle as follows: Ilio-hypogastric nerve L1 L2 Ilio-inguinal nerve Lateral cutaneous nerve of the thigh L3 L4 Genitofemoral nerve L5 Femoral nerve Obturator nerve Ilio-hypogastric nerve The ilio-hypogastric and ilio-inguinal nerves arise as a single trunk from the ventral ramus of L1 Either before or soon after emerging from the lateral border of the psoas major muscle, this single trunk divides into: The ilio-hypogastric nerve And The ilio-inguinal nerve Ilio-inguinal nerve L1 L1 L2 L3 L4 L5 Ilio-hypogastric nerve Ilio-inguinal nerve Genitofemoral Nerve L1 L2 L3 L4 L5 Genital branch of genitofemoral nerve Femoral branch of genitofemoral nerve Genitofemoral Nerve The genital branch The femoral branch: Distributed to the skin of the upper and intermediate part of the thigh (femoral branch runs with femoral artery) Ilio-inguinal nerve Distributed to the skin of the upper and medial part of the thigh Lateral cutaneous nerve of the thigh Distributed to the skin of the lateral aspect of the thigh Lateral Medial L1 L2 Obturator nerve Anterior divisions of L2 L3 L4 Supplies medial compartment of thigh L3 L4 L5 Femoral nerve Femoral nerve Posterior divisions of L2 L3 L4 Supplies anterior compartment of thigh Obturator nerve Anterior Anterior compartment Femoral nerve Extensor Femur Medial Lateral Medial compartment Obturator nerve Adductor Posterior compartment Sciatic nerve Flexor Posterior Lumbosacral trunk L4 L5 L1 L2 L3 L4 L5 The lumbosacral trunk is a thick nerve formed by the union of lower part of ventral ramus of L4 with the ventral ramus of L5 What is the key to memorize the lumbar plexus? Ilio-hypogastric nerve Ilio-inguinal nerve L1 L2 L3 Lateral cutaneous nerve of the thigh L4 L5 Femoral nerve L1 gives 1-Ilio-hypogastric nerve 2-Ilio-inguinal nerve 3-The first root of the genito-femoral L2 gives (four branches) 1-The second root of the genito-femoral 2-The first root of the lateral cutaneous nerve of the thigh 3-The first root of the femoral nerve 4-The first root of the obturator nerve L3 gives 1-The second root of the lateral cutaneous nerve of the thigh 2-The second root of the femoral nerve 3-The second root of the obturator nerve Obturator nerve Lumbo-sacral trunk L4 gives 1-The third root of the femoral nerve 2-The third root of the obturator nerve 3-The upper root of the lumbo-sacral trunk The Sacral plexus L1 L2 L3 L4 L5 S1 S2 S3 S4 S5 L4-S4  Located on the posterior wall of pelvis on the anterior surface of piriformis muscle  Formed by the lumbosacral trunk and ventral rami of S1 -S4  Branches supply: lower limb, pelvic floor and wall, and perineum  Most branches leave the pelvis through greater sciatic foramina Branches of the Sacral plexus Gluteal region Superior gluteal nerve (L4, L5, S1) Inferior gluteal nerve (L5, S1, S2) Posterior cutaneous nerve of the thigh (S1,S2 ,S3 S4) Sciatic nerve (L4,L5, S1, S2, S3) (All roots except S4) Tibial nerve (L4,L5, S1, S2, S3) (The same as sciatic) Common peroneal nerve (L4, L5, S1, S2) (The same root value as the tibial except S3) Nerve to obturator internus & superior gemellus Nerve to quadratus femoris & inferior gemellus Perforating cutaneous nerve Nerve to piriformis Sciatic nerve L4 L5 S1 S2 S3 L4 L5 S1 S2 S3 Tibial nerve anterior divisions of L4 L5 S1 S2 S3 L4 L5 S1 S2 S3 Common fibular nerve posterior divisions of L4 L5 S1 S2 L4 L5 S1 S2 S3 Superior gluteal nerve posterior divisions of L4 L5 S1 L4 L5 S1 S2 S3 Inferior gluteal nerve posterior divisions of L5 S1 S2 L4 L5 S1 S2 S3 Posterior cutaneous nerve of the thigh (S1,S2 ,S3) L4 L5 S1 S2 S3 Major nerves of the lumbar and sacral plexuses are: Anterior divisions Posterior divisions Obturator nerve anterior divisions of L2 L3 L4 Femoral nerve posterior divisions of L2 L3 L4 Tibial nerve anterior divisions of L4 L5 S1 S2 S3 Common fibular nerve posterior divisions of L4 L5 S1 S2 Superior gluteal nerve posterior divisions of L4 L5 S1 Inferior gluteal nerve posterior divisions of L5 S1 S2

Lumbar and Sacral Plexuses

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