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Lumbosacral Plexus

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(Redirected from Lumbar plexus)

Description

Formation of Lumbar Plexus[1]
Anatomy of the lumbar plexus[2]
Illustration of the lumbosacral plexus[3]
Anatomy of the sacral plexus[4]
A) Illustration of the lumbosacral plexus and the peripheral nerves relevant to the pelvic region; B) Sclerotomal distribution in the female; C) Sclerotomal distribution in the male[5]

Names

  • Lumbar Plexus
  • Sacral Plexus
  • Lumbosacral Plexus

Lumbar Plexus

Description

  • Network of nerve fibers supply skin, musculature of the lower body
  • Located in the lumbar region
  • Primarily within the psoas major muscle, anterior to the transverse processes of the lumbar vertebrae
  • Anterior rami of L1, L2, L3, L4, contributions from T12

Spinal Nerves

  • L1-L4 form the basis of the lumbar plexus
  • Each level: paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column
  • Each nerve divides into anterior and posterior nerve fibers
  • Lumbar plexus begins as the anterior fibers of L1-L4

Branches

  • Anterior rami of L1-L4 roots divide into cords
  • Cords combine to form the six major peripheral nerves of the lumbar plexus
  • Nerves descend down the posterior abdominal wall towards the lower limb

Iliohypogastric Nerve

Ilioinguinal Nerve

  • Follows a similar course to the iliohypogastric nerve
    • After innervating muscles of anterior abdominal wall
    • Passes through the inguinal ring to innervate the skin of the genitalia, middle thigh
  • Roots: L1
  • Motor: internal oblique, transversus abdominis
  • Sensory: Innervates the skin of the superior anteromedial thigh
    • Males (root of penis, anterior scrotum)
    • Females (mons pubis, labia majora)

Genitofemoral Nerve

  • After leaving psoas major
    • quickly divides into genital and femoral branches
  • Roots: L1, L2
  • Motor: Cremasteric Muscle
  • Sensory: upper anterior thigh
    • Males (anterior scrotum)
    • Females (mons pubis, labia majora)

Lateral Cutaneous Nerve of the Thigh

  • Purely sensory
  • Enters thigh lateral aspect of inguinal ligament
  • Roots: L2, L3
  • Motor: None
  • Sensory: anterior and lateral thigh down to the level of the knee
  • Clinical Significance

Obturator Nerve

Femoral Nerve

Sacral Plexus

Description

  • Network of nerves that supplies the skin and muscles of the pelvis and lower limb
  • Located on the surface of the posterior pelvic wall, anterior to the piriformis muscle
  • Nerves: anterior rami (divisions) of the sacral spinal nerves S1, S2, S3 and S4; contributions of L4 and L5

Spinal Nerves

  • Spinal Nerves: S1 to S4
  • Each level: paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column
  • Each nerve divides into the anterior and posterior nerve fibers

Lumbosacral Trunk

  • Sacral Plexus: begins as the anterior fibers of the spinal nerves S1, S2, S3, and S4
  • Joined by the 4th, 5th lumbar roots
  • This descends into the pelvis to meet the sacral roots as they emerge from the spinal cord

Branches

  • Anterior rami of S1-S4 roots divide into several cords
    • Along with the lumbosacral trunk
  • These combine to form the five major peripheral nerves of the sacral plexus
  • Descend down the posterior pelvic wall
  • Two main destinations:
    • Leave the greater sciatic foramen, enter the gluteal region of the lower limb
    • Remain in the pelvis and innervate the pelvic muscles, organs and perineum

Superior Gluteal Nerve

  • Leaves the pelvis via the greater sciatic foramen
    • Enters the gluteal region superiorly to the piriformis muscle
    • Accompanied by the gluteal artery, vein
  • Roots: L4, L5, S1
  • Motor: gluteus minimus, gluteus medius. tensor fascia lata
  • Sensory: none

Inferior Gluteal Nerve

  • Leaves via the greater sciatic foramen
    • Enters the gluteal region inferior to the piriformis muscle
  • Roots: L5, S1, S2
  • Motor: gluteus maximus
  • Sensory: none

Sciatic Nerve

Posterior Femoral Cutaneous Nerve

  • Leaves via the greater sciatic foramen
    • Enters the gluteal region inferiorly to the piriformis muscle
    • Descends deep to gluteus maximus, runs down the back of the thigh to the knee
  • Roots: S1, S2, S3
  • Motor: none
  • Sensory: posterior surface of the thigh and leg, skin of the perineum

Pudendal Nerve

  • Leaves via the greater sciatic foramen
    • Re-enters via lesser foramen
    • Moves anterosuperiorly along the lateral wall of the isciorectal fossa
    • Terminates by dividing into several branches
  • Roots: S2, S3, S4
  • Motor: skeletal muscles in the perineum, the external urethral sphincter, the external anal sphincter, levator ani
  • Sensory: penis and the clitoris and most of the skin of the perineum

Nerve to Obturator Internus

Other Branches

See Also

References

  1. ↑ Amudha, G., and Sandeep Diwan. "Anatomy of Lumbar Plexus and Implications to Regional Anesthesiologist." International Journal of Regional Anaesthesia 2.2 (2021): 102-106.
  2. ↑ Murinova, Natalia, Daniel Krashin, and Andrea M. Trescot. "Ilioinguinal nerve entrapment: pelvic." Peripheral Nerve Entrapments: Clinical Diagnosis and Management (2016): 467-477.
  3. ↑ Liyew, Worku Abie. "Clinical presentations of lumbar disc degeneration and lumbosacral nerve lesions." International journal of rheumatology 2020.1 (2020): 2919625.
  4. ↑ Liyew, Worku Abie. "Clinical presentations of lumbar disc degeneration and lumbosacral nerve lesions." International journal of rheumatology 2020.1 (2020): 2919625.
  5. ↑ Hunter, Corey W., et al. "Anatomy, pathophysiology and interventional therapies for chronic pelvic pain: a review." Pain Physician 21.2 (2018): 147.
Created by:
John Kiel on 19 September 2024 15:22:50
Authors:
Last edited:
18 March 2025 21:57:46
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