TOPIC 9 - nerves

Describe the sural nerve and its distribution

a sensory nerve in the posterior leg. It is made up of branches of the tibial nerve and common fibular nerve, the medial cutaneous branch from the tibial nerve, and the lateral cutaneous branch from the common fibular nerve. Sensory: skin of the lateral and posterior leg, heel and skin of the lateral side of the sole

Describe the tibial nerve and its distribution

A branch of the sciatic nerve descending posteriorly from the popliteal fossa to the medial malleolus Motor: gastroc, soleus, plantaris, tib post, FHL, FDL Sensory: knee and ankle joints

Describe the common peroneal nerve and its distribution

A branch of the sciatic nerve that runs laterally to the tibial nerve and wraps underneath head of fibula. Sensory: knee joint, skin of anterior posterior and lateral upper leg

Describe the superficial peroneal nerve and its distribution

A division of the common peroneal that runs laterally down the anterior of the leg alongside the fibula. Motor: peroneus longus and brevis Sensory: skin of lateral leg, dorsum of foot except skin between digits 1 and 2

Describe the deep peroneal nerve and its distribution

A division of the common peroneal that runs medially down the anterior of the leg between tibialis anterior and EHL. Motor: tib ant, EHL, EDL, peroneus tertius, extensor digitorum brevis Sensory: skin between digits 1 and 2

What is a plexus

All ventral rami split and merge repeatedly to form a 'plexus'.

What does the dorsal ramus supply

Dorsal ramus is distributed to the muscles of the back, and the skin covering those muscles. It is a lot smaller.

Describe the superior gluteal nerve and its distribution

Exits above piriformis Motor: glute med + min, TFL Sensory: hip joint

Describe the sciatic nerve and its distribution

Exits either below/through piriformis and branches off to supply posterior thigh. Motor: hamstrings, 1/2 adductor magnus

innervation of the hip joint

Femoral nerve Superior gluteal 2. Obturator n. 3. Sciatic n. 4. Superior gluteal n.5. Nerve to the quadratus femoris

Describe the posterior femoral cutaneous nerve and its distribution

Goes underneath piriformis, runs medially to sciatic nerve. Sensory: skin of posterior thigh and leg to mid calf

Describe the femoral nerve and its distribution

Input from L2, L3, L4, comes underneath the inguinal ligament before beginning to branch out. Motor distribution: iliacus, pectineus, sartorius, quadriceps group sensory distribution: skin of anterior thigh, knee and hip joints

Define ventral and dorsal rami

Sensory neurons entering the spinal cord are called 'the ventral root' and motor neurons exiting the spinal cord are called the 'ventral root'. Both roots merge shortly to form the 'spinal nerve' which exits through the intervertebral foramen. After this, it splits into dorsal and ventral rami.

Which nerve roots combine to form the lumbar plexus

L1, L2, L3, L4

state the root value of the femoral nerve

L2, L3, L4

state the root value of the obturator nerve

L2, L3, L4

Which nerve roots combine to form the lumbosacral plexus

L4, L5, S1, S2, S3

state the root value of the sciatic nerve

L4, L5, S1, S2, S3

Describe the saphenous nerve and its distribution

Longest branch of the femoral nerve which is purely sensory. It descends through the quadriceps and the medial side of the tibia before reaching the medial malleolus. Sensory: skin of the medial leg to base of great toe

Sensory nerves

Nerves that carry information from the sense receptors to the spinal cord and brain.

Describe the genitofemoral nerve and its distribution

Sensory: skin of medial thigh and the external genitalia

Describe the lateral femoral cutaneous nerve and its distribution

Sits across iliacus, goes underneath inguinal ligament and pops the side to supply lateral thigh. Sensory: skin of lateral thigh

Describe the lateral plantar nerve and its distribution

Terminal branch of the tibial nerve that supplies the lateral plantar surface of the foot. Motor: flexor digiti minimi, adductor hallucis, 2nd to 4th lumbricals, interossei, abductor digiti minimi, quadratus plantae Sensory: skin of lateral 1 and 1/2 digits and corresponding sole

Describe the medial plantar nerve and its distribution

Terminal branch of the tibial nerve that supplies the medial plantar surface of the foot. Motor: abductor hallucis, Flexor digitorum brevis, flexor hallucis brevis, 1st lumbrical Sensory: skin of the medial 2 and 1/2 digits and corresponding sole

Define spinal cord

The spinal cord is a major column of nerve tissue comprised of nerves and neuroglia that lies within the vertebral canal. It extends from the foramen magnum to the lumbar vertebral column, ending level with the L1-L2 disc.

What does the ventral ramus supply

Ventral ramus is distributed to the muscles of the anterior and lateral trunk, and the corresponding skin. Ventral rami are also distributed into the upper and lower limbs to supply the muscles and skin there.

Describe the inferior gluteal nerve and its distribution

comes out below piriformis Motor: glute max

define mixed nerves

contain both sensory and motor fibres, and thus conduct both incoming sensory information and outgoing muscle commands in the same bundle

define root value

from what levels the fibres originate to form the nerve

list the nerves in the lumbar plexus

genitofemoral nerve lateral femoral cutaneous nerve femoral nerve obturator nerve

motor nerves

nerves that conduct motor impulses from the brain to muscles and glands; also called efferent nerves

Describe the obturator nerve and its distribution

pops out through obturator foramen to supply medial thigh. Motor: pectineus, adductor brevis, adductor longus, 1/2 adductor magnus, obturator externus, gracilis Sensory: skin of medial thigh

list the nerves in the lumbosacral plexus

superior gluteal nerve inferior gluteal nerve posterior femoral cutaneous nerve sciatic nerve

general rule for nerve supply of joints

where a nerve supplies a muscle that moves a particular joint, the nerve will also supply that joint