Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Innervation of the Lower Limb Lecture PPT
NERVES OF THE LOWER LIMB
? Derived from the ventral (anterior primary) rami of
the lumbar and sacral nerves forming the lumbar
plexus (L1?L4) and the sacral plexus (L4?S4).
? Main nerves of the lower limb are
1. Femoral nerve.
2. Obturator nerve.
3. Sciatic nerve.
4. Tibial nerve.
5. Common peroneal nerve.
6. Superficial peroneal nerve.
7. Deep peroneal nerve.
FEMORAL NERVE
? Nerve of anterior compartment of the thigh
? It arises within the psoas major muscle from the
posterior divisions of the L2?L4 ventral rami in
the abdomen.
? It enters the thigh posterior to the inguinal
ligament just lateral to the femoral sheath.
? About 2 cm below the inguinal ligament it divides
into anterior and posterior divisions which are
separated by the lateral circumflex femoral artery.
? Motor branches supply iliacus in the abdomen
and all the muscles of anterior compartment
of the thigh.
? Cutaneous branches supply the large area on
the anterior and medial aspect of the thigh,
medial side of leg, and foot.
? Articular branches to the hip and knee joints.
? Injury of the femoral nerve:
? It is rare but may be injured by a stab, gunshot
wounds, or a pelvic fracture.
? The characteristic clinical features are :
(a) Motor loss
? Weak flexion of the thigh, due to paralysis of the
iliacus and sartorius muscles.
? Inability to extend the knee, due to paralysis of the
quadriceps femoris.
(b) Sensory loss
? Sensory loss over the anterior and medial aspects
of the thigh, due to involvement of the
intermediate and lateral cutaneous nerves of the
thigh.
? Sensory loss on the medial side of the leg and foot
up to the ball of the great toe (first
metatarsophalangeal joint), due to involvement of
the saphenous nerve.
? Femoral nerve neuropathy:
? Femoral nerve may be compressed by the
retroperitoneal tumors.
? A localized neuropathy of the femoral nerve may
occur in diabetes mellitus.
? The characteristic clinical features are :
(a) Wasting and weakness of quadriceps leading to
considerable difficulty in walking.
(b) Pain and paraesthesia on the anterior and medial
aspects of the thigh extending down along the
medial aspect of the leg and foot along the
distribution of the saphenous nerve.
OBTURATOR NERVE
? Chief nerve of the adductor compartment of the
thigh.
? It arises from the lumbar plexus in the abdomen.
? Formed by the ventral division of the anterior
primary rami of L2, L3, L4 spinal nerves.
? It enters the thigh by passing through the obturator
canal.
? Near the obturator foramen it divides into anterior
and posterior divisions.
? Motor branches supply all the muscles of the
adductor compartment of the thigh.
? Sensory branches supply cutaneous area on the
lower-half of the medial aspect of the thigh.
? Articular branches to the hip and knee joints.
? Injury of the obturator nerve:
? Due to anterior dislocation of the hip joint, or
during radical retropubic prostatectomy.
? The characteristic clinical features are :
(a)Motor loss: Loss of adduction of the thigh, due to
paralysis of adductor muscles of the thigh.
(b) Sensory loss: Sensory loss on the medial aspect of
thigh, due to involvement of the cutaneous branch
of the anterior division of the obturator nerve.
SCIATIC NERVE
? Thickest nerve in the body.
? Nerve of posterior compartment of the thigh.
? It arises in the pelvis from ventral rami of L4?S3
spinal nerves.
? It leaves the pelvis through greater sciatic
foramen below piriformis to enter the gluteal
region.
? Just above the popliteal fossa it divides into
terminal tibial and common peroneal nerves.
? Injury of the sciatic nerve:
? Cause
? Misplaced injection in the gluteal region (mc)
? Injured by penetrating wounds
? Posterior dislocation of the hip
? Fracture of the pelvis
? Total hip replacement surgery
? The characteristic clinical features are :
(a) Motor loss
? Inability to extend the thigh and flex the knee,
due to paralysis of the hamstring muscles.
? Loss of all movements below the knee with foot
drop, due to paralysis of all the muscles of the leg
and foot.
? The motor loss leads to flail foot which leads to
great difficulty in walking.
? The patient walks with high stepping gait.
(b) Sensory loss:
? The sensory loss on the back of the thigh and whole
of the leg and foot (except the area innervated by
the saphenous nerve)
? Due to involvement of the cutaneous nerves
derived from the tibial and common peroneal
nerves.
? SCIATICA
? It is a term applied to a clinical condition
? characterized by shooting pain felt along the course
of distribution of the sciatic nerve (e.g., buttock,
posterior aspect of thigh, lateral aspect of leg, and
dorsum of the foot).
? It occurs due to compression and irritation of L4?S3
spinal nerve roots by herniated intervertebral disc
of the lumbar vertebrae.
TIBIAL NERVE
? Larger terminal branch of the sciatic nerve.
? It arises above the popliteal fossa
? Passes downward successively through the middle
of popliteal fossa and posterior compartment of
the leg, and then enters the sole of the foot by
passing deep to the flexor retinaculum.
? It divides into the medial and lateral plantar
nerves.
? Effects of injury of the tibial nerve:
? Injured by a lacerated wound in the popliteal fossa
? posterior dislocation of the knee joint.
? The characteristic clinical features are :
(a) Motor loss:
? Foot is held dorsiflexed and everted, due to paralysis of
the muscles of posterior compartment of the leg.
? Loss of prominence of calf and tendocalcaneus, due to
paralysis of the triceps surae muscle (gastrocnemius
and soleus).
? Loss of plantar flexion of foot, due to paralysis of the
flexors of ankle.
? Inability to stand on the toes, due to loss of plantar
flexion of foot
(b) Sensory loss:
? The loss of sensation in the sole and plantar aspects
of the toes including the dorsal aspects of their
distal phalanges, due to involvement of the
cutaneous branches.
? Tarsal tunnel syndrome:
? It occurs due to compression of the tibial nerve in
the osseofibrous tunnel under the flexor
retinaculum of the ankle.
? It clinically presents as pain and paresthesia in the
sole of the foot, which often becomes worse at
night.
Morton's metatarsalgia (plantar digital neuroma)
? It occurs due to the formation of a
neuroma following pressure on
one of the plantar digital nerves
just prior to its bifurcation at one
of the toe clefts.
? It most commonly affects the
plantar digital nerve running
between the 3rd and 4th
metatarsal heads to the third web
-space
? it presents as intermittent pain on
the plantar aspect of the forefoot
usually between the 3rd and 4th
metatarsals.
COMMON PERONEAL NERVE
? Smaller terminal branch of the sciatic nerve.
? It arises just above the popliteal fossa.
? it divides into two terminal branches --deep and
superficial peroneal nerves.
? Effects of injury to the common peroneal nerve:
? The common peroneal nerve is extremely
vulnerable to injury as it winds around the
posterolateral aspect of the neck of the fibula.
? At this site it may be injured by the direct trauma,
fracture neck of fibula, or tightly applied plaster cast.
? The characteristic clinical features:
(a) Motor loss:
? Foot drop, due to the paralysis of
muscles of the anterior compartment
of the leg.
? Loss of extension of toes, due to the
paralysis of extensor digitorum longus
and extensor hallucis longus.
? Loss of eversion of foot, due to the
paralysis of peroneus longus and
peroneus brevis.
(b) Sensory loss:
-Due to involvement of the cutaneous
branches, on the anterolateral aspect
of the leg, and whole of dorsum foot
(except the areas supplied by the
saphenous and sural nerves).
CUTANEOUS INNERVATION OF THE LOWER LIMB
SEGMENTAL INNERVATION OF THE SKIN (DERMATOMES)
Area of the skin supplied by a spinal nerve is termed dermatome
This post was last modified on 30 November 2021