Nerves of Lower Limb Dr Fadel Naim Orthopedic

Nerves of Lower Limb Dr. Fadel Naim Orthopedic Surgeon Faculty of Medicine IUG

Nerves Of The Lower Limb l l The nerves entering the lower limb provide the following important functions: – Sensory innervation to the skin and deep structures such as the joints – Motor innervation to the muscles – Sympathetic vasomotor nerves that influence the diameters of the blood vessels – Sympathetic secretomotor supply to the sweat glands. Originate from: – The lumbar plexus, situated in the abdomen – The sacral plexus, situated in the pelvis

l The lumbar plexus is formed by the anterior rami of spinal nerves L 1 to L 3 and part of L 4. l The rest of the anterior ramus of L 4 and the anterior ramus of L 5 combine to form the lumbosacral trunk, l The lumbosacral trunk joins with the anterior rami of S 1 to S 3 and part of S 4 to form the sacral plexus.

Lumbosacral Plexus (Lumbar and Sacral Plexuses) l The major branches: Femoral (Lumbar) – Obturator (Lumbar) – Sciatic (Sacral) – l Tibial l Common – peroneal The posterior cutaneous nerve of the thigh (Sacral)

Lumbar Plexus l Formed in psoas major: From ventral rami of L 1 - L 4. – Branches emerge from both lateral and medial sides of psoas major –

Lumbar Plexus

Lumbar Plexus l L 1 variably connected to T 12 (subcostal) and L 2. – Two branches emerge from lateral side of psoas major: l Iliohypogastric: to side of buttock and pubis. l Ilioinguinal: to anterior thigh, scrotum labia majora.

Lumbar Plexus l Genitofemoral nerve: Emerges on anterior surface of psoas major. – Genital branch: Sensory motor – l l l – Enters inguinal canal. Supplies scrotum and labia majora Supplies cremaster muscle Femoral branch: purely sensory l l Enters femoral sheath. Supplies skin over femoral triangle.

Femoral Nerve The largest branch of the lumbar plexus (L 2, 3, and 4). l Emerges from lateral side of psoas major. l Supplies all the muscles of the anterior compartment of the thigh l – iliopsoas, pectineus, sartorius, and quadriceps femoris

Branches of Femoral Nerve l Anterior division – Two cutaneous l l – Two muscular branches. l l Medial cutaneous nerve of the thigh Intermediate cutaneous nerves of the thigh To the sartorius and the pectineus. Posterior division – – – The saphenous nerve to medial leg and foot. The muscular branch Quadriceps muscle DR FADEL NAIM IUG supplies the hip joint

DR FADEL NAIM IUG

Obturator Nerve l The obturator nerve arises from the lumbar plexus (L 2, 3, and 4) l Emerges on the medial border of the psoas muscle within the abdomen l It divides into anterior and posterior divisions

Branches of Obturator Nerve l The anterior division: – It gives muscular branches to: l The gracilis l Adductor brevis l Adductor longus l Occasionally to the pectineus. – – – It gives articular branches to the hip joint Terminates as a small nerve that supplies the femoral artery. Supplies the skin on the medial side of the thigh

Branches of Obturator Nerve l The posterior division – Supply the knee joint – It gives muscular branches to: l. The obturator externus l. The adductor part of the adductor magnus l. Occasionally to the adductor brevis.

Obturator Nerve The anterior division passes downward in front of the obturator externus. The posterior division pierces the obturator externus and passes downward behind the adductor brevis and in front of the adductor magnus 19

Sacral Plexus • The sacral plexus is formed by: • the lumbosacral trunk • the anterior devision of the 1 st sacral nerve • portions of the anterior divisions of the 2 nd and 3 rd sacral nerves

Sacral Plexus • provides motor and sensory nerves for • the posterior thigh • most of the lower leg • the entire foot • part of the pelvis

Sacral plexus

Branches of the Sacral Plexus 1. Nerve to quadratus femoris and gemellus inferior: L 4 -S 1 2. Nerve to obturator internus and gemellus superior: L 5 -S 2 3. Nerve to piriformis: S 1, S 2 4. Superior gluteal nerve: L 4 -S 1 5. Inferior gluteal nerve: L 5 -S 2 6. Posterior femoral cutaneous nerve: S 1 -S 3 7. Tibial nerve: L 4 -S 3 8. Common fibular (peroneal): L 4 -S 2

Posterior Cutaneous Nerve of the Thigh l l l A branch of the sacral plexus, enters the gluteal region through the lower part of the greater sciatic foramen below the piriformis muscle It passes downward on the posterior surface of the sciatic nerve and runs down the back of the thigh beneath the deep fascia. In the popliteal fossa it supplies the skin.

Posterior Cutaneous Nerve of the Thigh Branches l 1. 2. 3. Gluteal branches to the skin over the lower medial quadrant of the buttock Perineal branch to the skin of the back of the scrotum or labium majus. Cutaneous branches to the back of the thigh and the upper part of the leg

Superior Gluteal Nerve l Abranch of the sacral plexus l Leaves the pelvis through the upper part of the greater sciatic foramen above the piriformis l It runs forward between the gluteus medius and minimus l Supplies gluteus medius and minimus and ends by supplying the tensor fasciae latae.

Inferior Gluteal Nerve l l l A branch of the sacral plexus Leaves the pelvis through the lower part of the greater sciatic foramen below the piriformis It supplies the gluteus maximus muscle.

Nerve to the Quadratus Femoris l l l A branch of the sacral plexus Leaves the pelvis through the lower part of greater sciatic foramen It ends by supplying quadratus femoris and the inferior gemellus.

Pudendal Nerve and the Nerve to the Obturator Internus l l l Branches of the sacral plexus Leave the pelvis through the lower part of the greater sciatic foramen, below the piriformis They cross the ischial spine with the internal pudendal artery and immediately reenter the pelvis through the lesser sciatic foramen They then lie in the ischiorectal fossa The pudendal nerve supplies structures in the perineum. The nerve to the obturator internus supplies the obturator internus muscle

Sciatic Nerve l l A branch of the sacral plexus (L 4 and 5; SI, 2, and 3) Emerges from the pelvis through the lower part of the greater sciatic foramen It is the largest nerve in the body. Gives no branches in the gluteal region.

Intramuscular Injection

Sciatic Nerve l l The sciatic nerve usually consists of the tibial and common peroneal nerves bound together with fascia.

Branches of the sciatic nerve The tibial nerve l The common peroneal nerve l Muscular branches to: l – – the long head of the biceps femoris the semitendinosus the semimembranosus the hamstring part of the adductor magnus.

COMMON PERONEAL NERVE l l The smaller terminal branch of the sciatic nerve arises in the lower third of the thigh It then passes behind the head of the fibula, winds laterally around the neck of the bone it is subcutaneous and can easily be rolled against the bone

COMMON PERONEAL NERVE l Divides into two terminal branches: – – the superficial peroneal nerve the deep peroneal nerve

Deep Peroneal Nerve l l l One of the terminal branches of the common peroneal nerve The nerve enters the anterior compartment of the leg by piercing the anterior fascial septum. Branches – Muscular branches to: l l – The tibialis anterior The extensor digitorum longus The peroneus tertius The extensor hallucis longus. Articular branch to the ankle joint.

Superficial Peroneal Nerve l l l One of the terminal branches of the common peroneal nerve It arises on the lateral side of the neck of the fibula It descends between the peroneus longus and brevis muscles In the lower part of the leg it becomes cutaneous Muscular branches to – – The peroneus longus The peroneus brevis

Superficial Peroneal Nerve l Cutaneous. – – – Medial and lateral branches are distributed to the skin on the lower part of the front of the leg and the dorsum of the foot. Branches supply the dorsal surfaces of the skin of all the toes Except l l The adjacent sides of the first and second toes The lateral side of the little toe

TIBIAL NERVE l l The larger terminal branch of the sciatic nerve The tibial nerve arises in the lower third of the thigh. It runs downward through the popliteal fossa, The nerve enters the posterior compartment of the leg by passing beneath the soleus muscle.

Branches Tibial Nerve l Cutaneous. – l The sural nerve Muscular branches supply – – Both heads of the gastrocnemius The plantaris Soleus Popliteus Lateral and medial plantar nerves l Articular l – Branches supply the knee joint.

The Skin Of The Buttock l The cutaneous nerves are derived from posterior and anterior rami of spinal nerves – The upper medial quadrant – – The upper lateral quadrant – – Branches from the lateral cutaneous nerve of the thigh (L 2 and 3, anterior rami) The lower medial quadrant – – The lateral branches of the iliohypogastric and 12 th thoracic nerves (anterior rami) The lower lateral quadrant – – The posterior rami of the upper 3 lumbar nerves and the upper three sacral nerves. Branches from the posterior cutaneous nerve of the thigh (S 1, 2, and 3, anterior rami). The skin over the coccyx – Small branches of the lower sacral and coccygeal nerves

SKIN OF THE THIGH Cutaneous Nerves l The femoral branch of the genitofemoral nerve – – A branch of the lumbar plexus (L 1 and 2) Supplies a small area of skin

SKIN OF THE THIGH Cutaneous Nerves l The ilioinguinal nerve – – a branch of the lumbar plexus (Ll) It is distributed to the skin of the l l l root of the penis and adjacent part of the scrotum root of the clitoris and adjacent part of the labium majus in the female a small skin area below the medial part of the inguinal ligament

SKIN OF THE THIGH Cutaneous Nerves – The posterior cutaneous nerve of the thigh l. A branch of the sacral plexus l It descends on the back of the thigh, and in the popliteal fossa l It gives off numerous branches to the skin on the back of the thigh and the upper part of the leg

SKIN OF THE THIGH Cutaneous Nerves l The lateral cutaneous nerve of the thigh – – A branch of the lumbar plexus (L 2 and 3), enters the thigh behind the lateral end of the inguinal ligament Having divided into anterior and posterior branches It supplies the skin of the lateral aspect of the thigh and knee It also supplies the skin of the lower lateral quadrant of the buttock

Meralgia paresthetica l l l Compression on lateral cutaneous nerve of the thigh common in men than in women Paraesthesiae and often burning pain over the anterolateral aspect of the thigh. Prolonged standing, or sitting may provoke symptoms Whereas flexion of thigh on the pelvis improves symptoms

SKIN OF THE THIGH Cutaneous Nerves l The medial cutaneous nerve of the thigh – – – l A branch of the femoral nerve Supplies the medial aspect of the thigh Joins the patellar plexus The intermediate cutaneous nerve of the thigh – – – A branch of the femoral nerve Divides into two branches that supply the anterior aspect of the thigh Joins the patellar plexus

SKIN OF THE THIGH Cutaneous Nerves l Branches from the anterior division of the obturator nerve – Supply a variable area of skin on the medial aspect of the thigh

SKIN OF THE THIGH Cutaneous Nerves l The patellar plexus – – Lies in front of the knee Formed from the terminal branches of: l The lateral cutaneous nerves of the thigh l Intermediate cutaneous nerves of the thigh l Medial cutaneous nerves of the thigh l The infrapatellar branch of the saphenous nerve

The Back of the Leg Cutaneous Nerves l The posterior cutaneous nerve of the thigh descends on the back of the thigh – l In the popliteal fossa, it supplies the skin over the popliteal fossa and the upper part of the back of the leg The lateral cutaneous nerve of the calf, – a branch of the common peroneal nerve supplies the skin on the upper part of the posterolateral surface of the leg

The Back of the Leg Cutaneous Nerves l The sural nerve, – a branch of the tibial nerve supplies the skin on the lower part of the posterolateral surface of the leg l The saphenous nerve, – a branch of the femoral nerve gives off branches that supply the skin on the posteromedial surface of the leg

The Front of the Leg Cutaneous Nerves l The lateral cutaneous nerve of the calf – – l A branch of the common peroneal nerve Supplies the skin on the upper part of the lateral surface of the leg The superficial peroneal nerve, – – A branch of the common peroneal nerve Supplies the skin of the lower part of the antero- lateral surface of the leg

The Front of the Leg Cutaneous Nerves l The saphenous nerve, – – A branch of the femoral nerve Supplies the skin on the antero-medial surface of the leg

The sensory nerve supply of the foot l l The superficial peroneal nerve The deep peroneal nerve The saphenous nerve The sural nerve

The sensory nerve supply to the skin of the sole l medial side of the heel – l medial two thirds of the sole – l The medial calcaneal branch of the tibial nerve Branches from the medial plantar nerve lateral third of the sole – Branches from the lateral plantar nerve

The sensory nerve supply of the foot

The sensory nerve supply of the foot

The dermatomes of the lower body L 1: the upper, inner thigh L 2: 5 cm above the kneecap L 3: the kneecap L 4: 5 cm below the kneecap L 5: the lateral calf S 1: the little toe

Applied aspects: AFFECTED NERVE SENSORY LOSS FEMORAL NERVE Anterior side of thigh and medial side of leg upto big toe. SCIATIC NERVE Back and lateral side of leg, most of dorsum of foot, sole of foot. COMMON PERONEAL Lateral & anterior side of leg, most of dorsum of foot, most of digits. Skin of sole. Trophic ulcers can develop. TIBIAL Small area on the medial side of thigh. OBTURATOR SUPERIOR GLUTEAL INFERIOR GLUTEAL Skin of perineum PUDENDAL 1 st inter digital cleft DEEP PERONEAL Lateral side of leg, most of dorsum of foot. SUPERFICIAL PERONEAL

INJURED NERVE SENSORY LOSS MEDIAL PLANTAR Medial 2/3 rd of sole and digital nerves to medial 3 ½ toes, including nail beds. LATERAL PLANTAR Lateral 1/3 rd of sole and digital nerves to lateral 1 ½ toes, including nail beds.