Nerves of the Lower Limb and Femoral Nerve

Nerves of the Lower Limb

• Focus on compartments of the thigh and leg for understanding.
• The lower limb contains a collection of big nerves.
• Consider the muscles involved in running.

Femoral Nerve

• It supplies the anterior compartment of the thigh.
• The femoral region is the thigh.
• Arteries change names at the inguinal ligament, nerves change with branching
• Originates from the lumbar plexus in the abdomen.
• Courses deep relative to the inguinal ligament to enter the anterior thigh compartment
• Innervates quadriceps femoris and sartorius.
• The anterior thigh compartment facilitates knee extension and hip flexion.
• The saphenous nerve is a cutaneous branch, running through the subsartorial canal.
• The saphenous nerve provides sensory innervation to the medial knee, leg, and ankle

Compartments of the Thigh

• Consists of anterior, medial, and posterior compartments
• Muscles within are surrounded by fascia.
• The anterior compartment contains quadriceps femoris and sartorius, for knee extension and hip flexion.
• The medial compartment facilitates adduction.
• Gluteus medius and minimus facilitate abduction.
• Hamstrings and gluteus maximus facilitate hip extension and knee flexion (posterior compartment).

Obturator Nerve

• It supplies the medial compartment of the thigh.
• Courses around the pelvic brim and exits via the obturator foramen.
• Innervates all adductor muscles except part of adductor magnus.

Sciatic Nerve

• It supplies the posterior compartment of the thigh.
• Courses down the posterior thigh and splits into common fibular and tibial nerves.
• The splitting point is variable.
• The tibial division innervates most of the posterior thigh compartment.
• The short head of biceps femoris is supplied by the common fibular nerve.
• Gluteal muscles are supplied by branches of the sacral plexus, not the sciatic nerve.
• The superior gluteal nerve innervates gluteus medius and minimus.
• The inferior gluteal nerve innervates gluteus maximus.
• Gluteus medius and minimus contract to keep the pelvis level during single-leg stance during walking.
• Damage to gluteal nerves/muscles can cause hip drop on the opposite side, resulting in Trendelenburg gait.

Tibial Nerve

• It supplies the posterior leg.
• Courses down and passes deep to the ankle retinaculum.
• Splits into medial and lateral plantar nerves, which innervate the plantar surface of the foot.

Common Fibular Nerve

• It supplies the lateral and anterior compartments of the leg.
• Courses over the fibular head, splitting into deep and superficial fibular nerves.
• The superficial fibular nerve innervates the lateral leg compartment (fibularis brevis and fibularis longus).
• The deep fibular nerve innervates the anterior leg compartment.
• Superficial fibular nerve branches provide sensory innervation to the dorsum of the foot (medial and lateral dorsal cutaneous nerves).
• The deep fibular nerve provides sensory innervation to the skin between the great and second toes.

Compartments of the Leg

• Similar to the thigh, there are posterior, lateral, and anterior compartments.
• The tibial nerve runs through the posterior compartment.
• The superficial fibular nerve runs through the lateral compartment.
• The deep fibular nerve runs through the anterior compartment.