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Root value: L2, L3, L4 (posterior divisions of ventral rami).
Origin and course:
Arises in the abdomen within psoas major and emerges at its lateral border.
Descends between psoas major and iliacus, passes under the inguinal ligament into the thigh, lateral to the femoral artery.
Branches in the abdomen: to psoas major and iliacus.
Branches in the thigh:
Anterior cutaneous branches (medial and intermediate cutaneous nerves of thigh).
Muscular branches → sartorius, pectineus, quadriceps femoris.
Articular branches → hip and knee joints.
Saphenous nerve — the terminal sensory branch supplying the medial leg and foot.
Root value: L2, L3, L4 (ventral divisions).
Course:
Emerges from the medial border of psoas major, crosses the pelvic brim, and runs along the lateral wall of the pelvis to reach the obturator foramen.
Divides into anterior and posterior divisions separated by adductor brevis.
Branches:
Anterior division → pectineus, adductor longus, adductor brevis, gracilis, hip joint.
Posterior division → obturator externus, adductor magnus (adductor part), knee joint.
Cutaneous branch to the medial thigh.
Present in ≈ 30 % of people.
Root value: L3 and L4 (ventral divisions).
Course and branches:
Runs along the medial border of psoas major, crosses the superior ramus of pubis, passes behind pectineus.
Supplies pectineus, hip joint, and gives a communicating branch to the anterior division of the obturator nerve.
Root value: L4, L5, S1 (dorsal divisions).
Course: Leaves the pelvis through the greater sciatic foramen above piriformis, running between gluteus medius and gluteus minimus to end in tensor fasciae latae.
Branches: to gluteus medius, gluteus minimus, and tensor fasciae latae.
Clinical note: Injury → Trendelenburg gait due to loss of hip abductors.
Root value: L5, S1, S2 (dorsal divisions).
Course: Enters the gluteal region via the greater sciatic foramen below piriformis.
Branches: to gluteus maximus only — the main antigravity extensor of the hip.
Clinical note: Injury → difficulty in climbing stairs or rising from sitting.
Root value: L4, L5, S1 (ventral divisions).
Branches: to quadratus femoris, inferior gemellus, and the hip joint.
Root value: L5, S1, S2 (ventral divisions).
Course and branches: Leaves the pelvis through the greater sciatic foramen below piriformis, enters the lesser sciatic foramen, and supplies obturator internus and superior gemellus.
Largest nerve in the body.
Root value: L4, L5, S1, S2, S3 (mixed dorsal and ventral divisions).
Parts:
Tibial part — ventral divisions (L4–S3).
Common peroneal part — dorsal divisions (L4–S2).
Course:
Leaves the pelvis through the greater sciatic foramen below piriformis.
Descends deep to gluteus maximus, crosses gemelli, obturator internus, and quadratus femoris to enter the posterior thigh.
Lies between the ischial tuberosity and greater trochanter, then beneath the long head of biceps femoris.
Termination: At the upper angle of the popliteal fossa, divides into tibial and common peroneal nerves.
Clinical note: Injury causes foot drop and posterior-thigh sensory loss.
Root value: L4–S3 (ventral divisions).
Course:
Larger terminal branch of the sciatic nerve.
Passes through popliteal fossa, deep to soleus, along the posterior leg, and deep to flexor retinaculum.
Ends by dividing into medial and lateral plantar nerves.
Branches:
Muscular: To gastrocnemius, soleus, plantaris, popliteus, tibialis posterior, flexor digitorum longus, flexor hallucis longus.
Cutaneous: Medial calcaneal branches to heel.
Articular: Knee, ankle, and superior tibiofibular joints.
Terminal: Medial and lateral plantar nerves.
Clinical note:
Injury → paralysis of plantar flexors and intrinsic sole muscles → inability to stand on toes and loss of plantar sensation.
Leads to trophic ulcers on sole due to sensory loss
Volume 2, BD Chaurasia’s Human …
.Root value: L4–S2 (dorsal divisions).
Course:
Smaller terminal branch of the sciatic nerve.
Passes laterally along biceps femoris tendon, winds around neck of fibula, then divides into superficial and deep peroneal nerves.
Branches:
Muscular: To short head of biceps femoris.
Cutaneous: Lateral cutaneous nerve of calf.
Articular: Superior and inferior lateral genicular nerves; recurrent genicular.
Terminal: Deep and superficial peroneal nerves
Volume 2, BD Chaurasia’s Human …
.Clinical note:
Commonly injured at neck of fibula.
Leads to foot drop due to paralysis of dorsiflexors and evertors.
Root value: L4–S1.
Course:
Begins at the bifurcation of the common peroneal nerve.
Enters the anterior compartment of the leg with the anterior tibial artery.
Passes beneath extensor retinacula to end on the dorsum of the foot between the first and second toes.
Branches:
Muscular: To tibialis anterior, extensor digitorum longus, extensor hallucis longus, peroneus tertius, and extensor digitorum brevis.
Articular: To ankle and tarsal joints.
Cutaneous: First interdigital cleft.
Clinical note:
Injury → sensory loss in first web space and weakness of dorsiflexion.
Root value: L4–S1.
Course:
Arises in the lateral compartment of the leg; descends between peroneus longus and brevis; pierces fascia in the lower third of leg.
Branches:
Muscular: Peroneus longus and peroneus brevis.
Cutaneous: Skin of lower anterolateral leg and most of the dorsum of foot except first web space.
Clinical note:
Injury → sensory loss over dorsum of foot with weak eversion
Volume 2, BD Chaurasia’s Human …
.Both arise from the tibial nerve beneath the flexor retinaculum
Volume 2, BD Chaurasia’s Human …
.
Larger terminal branch — analogous to the median nerve of the hand.
Course: Between abductor hallucis and flexor digitorum brevis.
Branches:
Muscular: Abductor hallucis, flexor digitorum brevis, first lumbrical, flexor hallucis brevis.
Cutaneous: Medial 3½ toes and adjacent nail beds.
Articular: Joints of medial 2/3 of foot.
Smaller terminal branch — corresponds to the ulnar nerve of the hand.
Course: Runs obliquely between the first and second layers of the sole to the base of 5th metatarsal, dividing into superficial and deep branches.
Branches:
Superficial branch: Supplies 4th dorsal interosseous, flexor digiti minimi brevis, digital nerves to 4th web space.
Deep branch: Supplies 2nd–4th lumbricals, adductor hallucis, and all interossei.
Cutaneous area: Lateral 1½ toes and lateral third of sole
Volume 2, BD Chaurasia’s Human …
.Main arteries and their features
Volume 2, BD Chaurasia’s Human …
:
| Artery | Course / Branches | Area Supplied |
|---|---|---|
| Femoral artery | Continuation of external iliac artery; passes through femoral triangle → adductor canal → becomes popliteal artery. | Thigh muscles and skin. |
| Popliteal artery | Continuation of femoral artery through adductor hiatus; ends at lower border of popliteus → divides into anterior and posterior tibial arteries. | Knee joint, leg muscles. |
| Anterior tibial artery | Passes through interosseous membrane → dorsalis pedis artery at ankle. | Anterior leg and dorsum of foot. |
| Posterior tibial artery | Larger branch; runs with tibial nerve → divides into medial and lateral plantar arteries. | Posterior leg and sole. |
| Peroneal (fibular) artery | Branch of posterior tibial artery; runs along fibula. | Lateral and posterior compartments of leg. |
| Medial and Lateral plantar arteries | Terminal branches of posterior tibial artery; form plantar arch. | Sole and toes. |
Causes: Pelvic or inguinal trauma, retroperitoneal hematoma, diabetic neuropathy.
Motor loss: Paralysis of quadriceps femoris → loss of knee extension and weakened hip flexion.
Sensory loss: Over anterior thigh and medial side of leg and foot (via saphenous nerve).
Clinical sign: Knee-jerk reflex absent.
Causes: Pelvic surgery, obturator hernia, childbirth.
Motor loss: Paralysis of adductor muscles → weakness of thigh adduction.
Sensory loss: Small patch on medial thigh.
Gait disturbance: Patient widens stance while walking.
Cause: Faulty gluteal intramuscular injection, pelvic fracture.
Effect: Paralysis of gluteus medius and minimus.
Sign: Positive Trendelenburg sign — pelvis falls on unsupported side when standing on one leg.
Gait: Compensatory lurch toward the affected side.
Effect: Paralysis of gluteus maximus → loss of power in hip extension.
Clinical feature: Difficulty in climbing stairs, running, or rising from sitting.
Common causes: Hip dislocation, posterior intramuscular injection, pelvic tumors.
Motor loss: Hamstrings and all muscles below knee → foot drop and flail limb.
Sensory loss: Posterior thigh, leg, and most of the foot.
Special note: Pain radiating down leg is sciatica, due to L4–S3 root irritation by herniated disc.
Vulnerable site: Around neck of fibula (superficial course).
Motor loss: Dorsiflexors and evertors of foot → foot drop with steppage gait.
Sensory loss: Lateral and anterior leg and most of dorsum of foot.
Ankle jerk: Remains intact (tibial nerve spared).
Cause: Tight footwear, anterior-compartment syndrome.
Motor loss: Weak dorsiflexion of ankle and extension of toes.
Sensory loss: Small area between first and second toes (first web space).
Result: “Ski-boot neuropathy.”
Cause: Lateral leg trauma, fibular fracture.
Motor loss: Weakness of eversion of foot.
Sensory loss: Over anterolateral leg and dorsum of foot except first web space.
Causes: Popliteal fossa trauma, posterior dislocation of knee, tarsal-tunnel compression.
Motor loss: Paralysis of plantar flexors and intrinsic muscles of sole → loss of toe flexion, inability to stand on toes.
Sensory loss: Entire sole and plantar aspects of toes.
Chronic complication: Trophic ulcers on sole due to anesthesia.
Medial plantar nerve:
Pain or burning in medial sole and toes (“Jogger’s foot”).
Loss of sensation over medial 3½ toes.
Lateral plantar nerve:
Affects small intrinsic muscles; loss of sensation on lateral 1½ toes.
May mimic ulnar-nerve lesion of the hand.
Cause: Atherosclerosis at the ankle.
Sign: Absent posterior tibial pulse posterior to the medial malleolus.
Effect: Ischemic pain and ulceration of toes and sole.
Site: Lateral to tendon of extensor hallucis longus on dorsum of foot.
Clinical relevance: Absence of pulse indicates peripheral arterial occlusive disease (PAOD).
Clinical test: Distinct pulsatile swelling below the inguinal ligament.
Complication: Femoral hernia may compress the artery or vein.
Femoral-pulse site: Mid-inguinal point — crucial for arterial cannulation or pressure control in hemorrhage.
Clinical sign: Pulsatile mass in popliteal fossa with bruit.
Complication: May compress tibial nerve → calf pain and sensory deficit.
Palpation: Flex the knee and feel deeply in the mid-fossa.
Cause: Increased intracompartmental pressure after trauma or tight cast.
Result: Compression of deep peroneal nerve and anterior tibial vessels.
Sign: Severe pain, weakness of dorsiflexion, sensory loss in first web space.
Management: Emergency fasciotomy.
Common sites: Femoral bifurcation, popliteal artery, posterior tibial artery.
Clinical triad: Claudication pain → loss of pulse → ischemic ulcer/gangrene.
Diagnosis: Doppler or angiography.
Cause: Valve incompetence in great or small saphenous veins.
Clinical feature: Dilated, tortuous superficial veins and pitting edema.
Complication: Chronic ulceration over the medial malleolus.
Cause: Prolonged immobilization or hypercoagulability.
Sign: Swelling, tenderness, increased local temperature of calf.
Risk: Pulmonary embolism if thrombus dislodges.
Arterial ulcer: Painful, distal, with pale necrotic edges and absent pulses.
Venous ulcer: Shallow, over medial malleolus, with pigmentation and edema.
| Structure Involved | Key Deficit / Sign | Classic Presentation |
|---|---|---|
| Femoral nerve | Weak knee extension | Loss of patellar reflex |
| Sciatic nerve | Foot drop & sensory loss | Posterior thigh pain |
| Common peroneal | Painless foot drop | Steppage gait |
| Tibial nerve | Loss of plantar flexion | Cannot stand on toes |
| Posterior tibial artery | Absent pulse | Claudication & ulcer |
| Dorsalis pedis artery | Absent pulse | Ischemic foot |
| Great saphenous vein | Dilatation | Varicose veins |
| Deep peroneal nerve | Loss between toes | Ski-boot neuropathy |
Rhythmic involuntary contractions of calf muscles following sudden dorsiflexion of the foot; a sign of upper motor-neuron lesion.
Raised pressure in the anterior compartment of the leg compresses the deep peroneal nerve and anterior tibial artery, producing severe pain and foot-drop.
Cramping pain in the calf on walking, relieved by rest, caused by femoral or popliteal arterial insufficiency.
Formation of thrombus in deep veins of the leg (especially in the calf). Presents with pain, swelling, and warmth; dangerous because of risk of pulmonary embolism.
Paralysis of dorsiflexors due to lesion of common or deep peroneal nerve; foot hangs in plantar flexion, producing steppage gait.
Loss of medial longitudinal arch from weakening of ligaments or plantar aponeurosis; may be congenital or acquired in long-standing cases.
Hyperextension of metatarsophalangeal joint with flexion of interphalangeal joints, often due to ill-fitting footwear or muscle imbalance.
Pain during exercise (walking or running) due to ischemia from arteriosclerosis obliterans of femoral or popliteal arteries.
Necrosis and fibrosis of flexor muscles of leg following ischemia from compartment syndrome; produces claw-like deformity of toes.
Exaggerated medial longitudinal arch of the foot, usually from imbalance between flexor and extensor muscles or upper motor-neuron disease.
Localized dilatation of the popliteal artery causing pulsatile swelling in the fossa and possible compression of the tibial nerve.
Pain radiating along the course of the sciatic nerve, usually from herniation of the lower lumbar intervertebral disc compressing L4–S3 roots.
Compression of the tibial nerve beneath the flexor retinaculum behind the medial malleolus; produces burning pain and paresthesia in the sole.
Dropping of the pelvis on the unsupported side due to paralysis of gluteus medius and minimus (superior gluteal nerve injury).
Dilated, tortuous superficial veins (usually great saphenous) caused by valve incompetence and chronic venous stasis; may lead to venous ulcers.
Pain along the tibia from repetitive traction injury to tibialis anterior origin during overuse (running, marching).
Failure of venous valves leading to reflux of blood, venous dilatation, edema, and chronic ulceration.
Surgical decompression of a tight fascial compartment to relieve ischemia and prevent muscle necrosis, especially in anterior compartment syndrome.
Palpated with the knee flexed; its absence may indicate popliteal artery occlusion or embolism.
Felt behind the medial malleolus; absent in peripheral arterial occlusive disease.
The femoral nerve arises from which spinal segments?
A. L2–L4 B. L1–L3 C. L3–L5 D. L4–S1
→ Correct Answer: A
The obturator nerve supplies all of the following except:
A. Gracilis B. Pectineus C. Adductor longus D. Adductor brevis
→ Correct Answer: B
The superior gluteal nerve supplies:
A. Gluteus maximus B. Gluteus medius C. Piriformis D. Quadratus femoris
→ Correct Answer: B
Injury to the inferior gluteal nerve results in:
A. Foot drop B. Inability to abduct thigh C. Inability to extend hip D. Loss of knee jerk
→ Correct Answer: C
Trendelenburg gait occurs due to paralysis of:
A. Gluteus maximus B. Gluteus medius C. Tensor fasciae latae D. Iliopsoas
→ Correct Answer: B
The nerve commonly injured at the neck of the fibula is:
A. Tibial B. Common peroneal C. Deep peroneal D. Sural
→ Correct Answer: B
Foot drop results from lesion of:
A. Deep peroneal nerve B. Tibial nerve C. Femoral nerve D. Saphenous nerve
→ Correct Answer: A
The posterior compartment of the leg is supplied by:
A. Superficial peroneal nerve B. Tibial nerve C. Deep peroneal nerve D. Sural nerve
→ Correct Answer: B
Medial plantar nerve is analogous to which nerve of the hand?
A. Median B. Ulnar C. Radial D. Axillary
→ Correct Answer: A
Lateral plantar nerve corresponds to which nerve of the hand?
A. Ulnar B. Median C. Radial D. Musculocutaneous
→ Correct Answer: A
The main artery of the gluteal region is:
A. Superior gluteal B. Inferior gluteal C. Femoral D. Profunda femoris
→ Correct Answer: A
The main artery of the anterior compartment of the leg is:
A. Posterior tibial B. Anterior tibial C. Peroneal D. Popliteal
→ Correct Answer: B
The dorsalis pedis artery is a continuation of:
A. Popliteal artery B. Posterior tibial artery C. Anterior tibial artery D. Peroneal artery
→ Correct Answer: C
The pulse of the dorsalis pedis artery is felt:
A. Behind medial malleolus B. Lateral to extensor hallucis longus tendon C. In popliteal fossa D. Over femoral triangle
→ Correct Answer: B
Varicose veins commonly involve:
A. Deep veins B. Perforating veins C. Great saphenous vein D. Popliteal vein
→ Correct Answer: C
Tarsal tunnel syndrome involves compression of:
A. Common peroneal nerve B. Tibial nerve C. Deep peroneal nerve D. Sural nerve
→ Correct Answer: B
Foot drop in anterior compartment syndrome is due to involvement of:
A. Deep peroneal nerve B. Tibial nerve C. Femoral nerve D. Lateral plantar nerve
→ Correct Answer: A
Popliteal artery aneurysm may compress:
A. Tibial nerve B. Common peroneal nerve C. Femoral nerve D. Obturator nerve
→ Correct Answer: A
The posterior tibial pulse is best felt:
A. Over dorsum of foot B. Behind medial malleolus C. In popliteal fossa D. Over adductor canal
→ Correct Answer: B
The artery supplying the lateral compartment of the leg is:
A. Anterior tibial B. Peroneal C. Posterior tibial D. Dorsalis pedis
→ Correct Answer: B
Femoral triangle
Adductor canal
Popliteal fossa
Great saphenous vein (at ankle)
Small saphenous vein (behind lateral malleolus)
Femoral artery (in femoral triangle)
Popliteal artery
Posterior tibial artery (behind medial malleolus)
Dorsalis pedis artery
Medial malleolus
Lateral malleolus
Head of fibula
Tibial tuberosity
Patella
Anterior superior iliac spine (ASIS)
Ischial tuberosity
Greater trochanter
Saphenous opening
Flexor retinaculum (medial ankle)
Superior and inferior extensor retinacula
Gluteal region (site for intramuscular injection)
Posterior superior iliac spine (PSIS)
Sciatic nerve (gluteal region)
Trendelenburg test site
Popliteal pulse site
Posterior tibial pulse site
Femoral pulse site
Adductor tubercle
Tendo calcaneus (Achilles tendon)
Plantar aponeurosis (sole)
Femoral triangle: Upper third of thigh below inguinal ligament, bounded by inguinal ligament, sartorius, and adductor longus.
Adductor canal: Middle third of thigh between vastus medialis and adductor longus.
Popliteal fossa: Posterior knee area bounded by biceps femoris (laterally) and semimembranosus + semitendinosus (medially).
Great saphenous vein: In front of the medial malleolus.
Small saphenous vein: Behind the lateral malleolus, along the tendocalcaneus.
Femoral artery: From midinguinal point to adductor tubercle.
Popliteal artery: Midline of fossa from adductor hiatus to lower border of popliteus.
Posterior tibial artery: Behind medial malleolus between tendocalcaneus and malleolus.
Dorsalis pedis artery: Lateral to tendon of extensor hallucis longus on dorsum of foot.
Medial malleolus: Medial ankle prominence of tibia.
Lateral malleolus: Lateral ankle prominence of fibula.
Head of fibula: Palpable on lateral aspect just below knee joint.
Tibial tuberosity: Below patella, insertion of ligamentum patellae.
Patella: Largest sesamoid bone in front of knee.
ASIS: Anterior end of iliac crest; attachment of inguinal ligament.
Ischial tuberosity: Inferior projection of ischium; weight-bearing while sitting.
Greater trochanter: Lateral prominence below neck of femur.
Saphenous opening: 4 cm below and lateral to pubic tubercle.
Flexor retinaculum: Between medial malleolus and medial side of heel.
Extensor retinacula: Superior—between tibia and fibula; Inferior—Y-shaped on dorsum of foot.
Gluteal injection site: Upper outer quadrant of buttock (safe zone).
PSIS: Dimple on posterior iliac crest level with S2 spine.
Sciatic nerve: Midway between ischial tuberosity and greater trochanter.
Trendelenburg test: Standing on one leg to test superior gluteal nerve integrity.
Popliteal pulse: Deep in popliteal fossa with knee flexed.
Posterior tibial pulse: Behind medial malleolus.
Femoral pulse: At midinguinal point.
Adductor tubercle: Bony projection above medial condyle of femur.
Tendo calcaneus: Thick tendon behind ankle; insertion of gastrocnemius + soleus.
Plantar aponeurosis: Thick central fascia in sole maintaining arches of foot.
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