Lower Limb Dermatomes: Page 24

The obturator nerve solely innervates the adductor longus and brevis muscles, without contributing to the innervation of adductor magnus.

The common peroneal part of the sciatic nerve innervates the long head of the biceps femoris.

The inferior gluteal nerve innervates gluteus medius and minimus, while the superior gluteal nerve supplies gluteus maximus.

The tibial nerve is the principal nerve of the anterior compartment of the leg, responsible for innervating the dorsiflexor muscles.

The superficial peroneal nerve innervates the anterior compartment of the leg, facilitating dorsiflexion and toe extension.

Preganglionic sympathetic fibers originating from spinal cord segments T1-L2 provide exclusive innervation to the sweat glands and arrectores pilorum muscles of the lower limb, bypassing vascular smooth muscle.

The lateral cutaneous nerve of the calf is a direct branch of the femoral nerve, providing sensory innervation to the lateral aspect of the lower leg.

The saphenous nerve, a terminal cutaneous branch of the obturator nerve, provides sensory innervation to the medial aspect of the leg and foot.

A lesion exclusively affecting the superficial peroneal nerve would result in a complete loss of sensation over the dorsum of the foot and impaired eversion, without affecting ankle dorsiflexion.

Severing the grey ramus communicans at the L4 level would exclusively impair voluntary motor function of muscles innervated by the L4 spinal nerve root, while sparing autonomic functions such as sweating and piloerection.

The dermatomal representation of the buttocks is exclusively constituted by posterior rami originating from the L4-S5 spinal segments, thereby excluding contributions from the ventral rami of the lumbar plexus.

The posterior femoral cutaneous nerve demonstrates a consistent and singular distribution, uniformly terminating its cutaneous sensory field precisely at the superior margin of the popliteal fossa in all individuals, without proximal or distal variations.

In the posterior compartment of the thigh, the cutaneous territories of the lateral and medial femoral cutaneous nerves are arranged such that the medial femoral cutaneous nerve is positioned lateral to the posterior femoral cutaneous nerve, and the lateral femoral cutaneous nerve is medial to it, creating a reversed topographical organization.

The obturator nerve's cutaneous contribution to the lower limb exhibits a predictable and extensive distribution, consistently encompassing the entirety of the medial aspect of the thigh and extending distally to the medial malleolus in the majority of subjects.

The anterior thigh dermatome is exclusively innervated by terminal branches of the femoral nerve, with no discernible contribution from the ilioinguinal, subcostal, or genitofemoral nerves, thereby representing a solely femoral nerve derived cutaneous field.

Cutaneous innervation of the anterior knee is solely and uniformly provided by branches originating from the femoral nerve, specifically the medial femoral cutaneous and saphenous nerves, thus excluding contributions from the common peroneal nerve or its branches.

The lateral cutaneous nerve of the calf consistently terminates its sensory distribution at the level of the mid-calf, with no ramifications extending distally towards the ankle or foot regions in typical anatomical presentations.

The saphenous nerve, a purely sensory branch of the femoral nerve, maintains a consistent cutaneous distribution terminating precisely at the distal interphalangeal joint of the hallux in all individuals, exhibiting minimal anatomical variability.

The superficial and deep peroneal nerves exhibit a strictly demarcated and mutually exclusive cutaneous territory distribution, with the superficial peroneal nerve exclusively innervating the dorsal interdigital clefts and the deep peroneal nerve solely supplying the dorsum of the foot proper.

The medial plantar nerve, analogous to the median nerve in the hand in terms of digital innervation, invariably provides sensory innervation to precisely four and a half digits on the plantar aspect of the foot, consistently including the entire hallux and extending to the radial half of the fourth digit.

Subcostal and Iliohypogastric Nerves

Posterior Rami (L1-L3, S1-S3)

Perforating Cutaneous Nerve

Posterior Femoral Cutaneous Nerve

Ilioinguinal Nerve

Intermediate Femoral Cutaneous Nerve

Obturator Nerve

Lateral Cutaneous Nerve of the Calf

Saphenous Nerve

Superficial Peroneal Nerve

Tibial Nerve

Inferior Gluteal Nerve

Superior Gluteal Nerve

Adductor Magnus Innervation

Tibial Nerve (Leg)

Common Peroneal Nerve

Deep Peroneal Nerve

Grey Ramus Communicans