Anatomy study note · Lower limb

Sciatic nerve

The largest nerve in the body (L4–S3): the tibial and common fibular nerves bound together. It supplies the hamstrings and, through its branches, all the muscles below the knee.

Key points

• L4–S3; largest nerve.
• Below piriformis; no gluteal branches.
• Tibial + common fibular parts; divides above the popliteal fossa.
• Hip dislocation (posterior) → sciatic injury.
• Upper limb nerves: C4–T2 segments; lower limb: L2–S2.
• Ventral root: basal-lamina neurons. Dorsal root: neural-crest ganglion cells.
• Nerve: epineurium → perineurium (blood–nerve barrier) → endoneurium.
• Cut nerve: Wallerian degeneration; regrows 0.5–3 mm/day.

The full note in the atlas also covers

Course · Branches · Histology · Development · Clinical notes

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Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 11, PDF pp. 1284–1287; ch. 8, PDF p. 1041
• Inderbir Singh’s Human Embryology, ch. 17, PDF pp. 318, 321, 323–325; ch. 10, PDF pp. 143–144
• BRS Cell Biology & Histology, 7th ed., ch. 9, PDF pp. 163–166, 171–172

More from the lower limb

• Semimembranosus
• Semitendinosus
• Short lateral rotators of the hip
• Small saphenous vein
• Sole muscles: first layer
• Sole muscles: second layer
• Sole muscles: third layer
• Soleus
• Superficial fibular nerve
• Sural nerve
• Tarsal bones
• Tarsal joints and arches of the foot

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