Anatomy (PNS) · MU Sofia

193. Ischiatic nerve.

Covers the sciatic nerve, the largest nerve of the body, starting with its origin from the lumbar and sacral segments of the sacral plexus. It then follows the nerve's course from the pelvis through the greater sciatic foramen below the piriformis, down the posterior thigh, to its split into the tibial and common fibular nerves. Branches are described with their segmental levels, motor and sensory territories, and the sural and lateral cutaneous nerves, with three pictures illustrating the origin and course.

Inside: 3 sections · 3 labelled pictures · 10 flashcards · 2 min

Topic 14 of 44 in the MU Sofia syllabus for Anatomy (PNS) (Medicine, Year 2). The free AceMed note covers it in 3 sections, about 223 words (2 min of reading), with 10 flashcards.

In this note

  1. 193 SCIATIC NERVE (nerve of the lower limb)
  2. Course :
  3. Branches :

193 SCIATIC NERVE (nerve of the lower limb)

  • Origin : L4, L5, S1, S2, S3 ( sacral plexus)
  • The sciatic nerve is the largest nerve of the body.
  • The sciatic nerve plays a crucial role in providing motor & sensory innervation to the lower limb.

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Course :

  • Leaves the pelvis through the greater sciatic foramen below the piriformis
  • Course through posterior thigh.
  • Bifurcates into tibial and common fibular (peroneal)
  • * It can also be described as two individual nerves bundled together in the same connective tissue.
  • * In some individuals the sciatic n. can birfucates as soon as it leaves the pelvis
  • * Tibial n. → Medial sural cutaneus
  • common fibular n. → sural communicating br.
  • → Sural nerve S: Skin of the post. surface of the leg.

Branches :

  • Tibial n. (L4-S3) : this branch continues down the post. leg, providing motor innervation to the post. compartment of the leg & foot.
  • ↳ It carries sensory information from the sole of the foot.
  • Common Fibular (Peroneal) nerve (L4-S2): This branch travels laterally around the knee & provides motor innervation to the muscles in the anterior & lateral compartments of the leg.
  • ↳ It carries sensory information from the dorsum (top) of the foot & antolateral leg.
  • superficial: m: Fibularis longus & brevis; S: skin of the dorsum of the foot.
  • Deep: S: foot. m:
  • lateral cutaneus n.

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