nerves Flashcards
Sciatic nerve roots
ventral rami of L4-S3
Tibial nerve roots
Medial terminal branch of the sciatic nerve.
Formed by anterior divisions of ventral rami of L4-S3
Superficial peroneal nerve roots
It is a continuation of the common peroneal nerve L4-S2
Deep peroneal nerve roots
It is a continuation of the common peroneal nerve L4-S2
Radial nerve roots
posterior cord of brachial plexus C5-T1
Posterior interosseous nerve roots
Continuation of the radial nerve, posterior cord C5-T1
Median nerve roots
lateral cord C5-C7 and medial cord C8-T1 of the brachial plexus
Ulnar nerve roots
medial cord of brachial plexus C7-T1
Sciatic nerve course
Enters the gluteal region through the greater sciatic foramen, beneath the piriformis muscle. It descends over the lateral rotators of the hip. It passes through the posterior compartment of the thigh to reach the superior border of the popliteal fossa, where it divides into 2 branches - the Tibial nerve and the Common Fibular (peroneal) nerve.
Tibial nerve course
It continues the course of the sciatic nerve through the popliteal fossa. It enters the lower leg under the tendinous arch of soleus. It descends between flexor digitorum longus and flexor hallucis longus and passes behind the medial malleolus, deep to the flexor retinaculum. It enters the plantar aspect of the foot and divides into the medial and lateral plantar nerves.
Superficial peroneal (fibular) nerve course
Having passed around the neck of the fibula, it descends vertically between extensor digitorum longus and Fibularis (peroneus) longus, anterior to the fibula. It becomes superficial halfway down the leg and divides into its terminal branches – the medial and intermediate dorsal cutaneous nerves.
Deep peroneal (fibular) nerve course
It passes inferomedially into the anterior compartment of the leg, deep to extensor digitorum longus. It descends on the interosseous membrane, deep to extensor hallucis longus and the superior extensor retinaculum. It enters the dorsum of the foot and lies between the tendons of extensor hallucis longus and extensor digitorum longus and divides into medial and lateral branches.
Radial nerve course
Descends against the posterior axillary wall and passes through the lower triangular space to descend within the spiral radial groove. It pierces the lateral intermuscular septum to enter the anterior arm before reaching the cubital fossa.
Posterior interosseous nerve course
This nerve commences at the front of the lateral epicondyle of the humerus and enters the posterior compartment through the two heads of supinator. It curves around the lateral and posterior surfaces of the radius. It descends between the deep and superficial group of extensor muscles. The nerve lies on the interosseous membrane and ends in a flattened expansion.
median nerve course
The nerve descends under the cover of biceps. In the lower arm it lies on brachialis and crosses the bicipital aponeurosis in the cubital fossa. It enters the forearm by passing between the 2 heads of pronator teres. It descends on flexor digitorum profundus until just above the wrist where it becomes superficial. The median nerve enters the hand deep to the flexor retinaculum (within the carpal tunnel). It then divides into lateral and medial terminal branches.
ulnar nerve course
Descends on the medial side of the brachial artery and pierces medial intermuscular septum to enter the posterior arm. Passes behind the medial epicondyle of the humerus, to descend in the forearm. The nerve enters the palmar aspect of the hand.
sciatic nerve sensory and motor supply
sensory - It has no cutaneous supply
motor - semitendinosus, semimembranosus, biceps femoris and the hamstring part of adductor magnus.
Tibial nerve sensory and motor supply
sensory - The Tibial nerve gives rise to the Sural nerve, a cutaneous branch. This nerve gives a sensory supply to the skin over the posterior and lateral sides of the lower third of the leg, the lateral border of the foot and 5th toe. The Tibial nerve also gives a cutaneous branch to the heel and posterior part of the foot.
motor - gastrocnemius, soleus, plantaris, popliteus, tibialis posterior, flexor digitorum longus and flexor hallucis longus
Superficial peroneal nerve sensory and motor supply
sensory - The nerve has a cutaneous supply to the anterolateral aspect of the leg and around the lateral malleolus. The medial dorsal cutaneous nerve supplies the medial side of the dorsum of the foot, great toes, and 2nd and 3rd toes. The intermediate dorsal cutaneous nerve supplies the dorsum of the foot and the 3rd, 4th and 5th toes.
motor - Fibularis (peroneus) longus and brevis
Deep peroneal nerve sensory and motor supply
sensory - The medial branch has a cutaneous supply to the cleft between the great and second toes
motor - extensor digitorum longus, tibialis anterior, extensor hallucis longus, and Fibularis (peroneus) tertius
Radial nerve sensory and motor supply
sensory - The radial nerve has 3 cutaneous branches which supply the skin on the back of the arm and forearm. These are the: Posterior cutaneous nerve of the arm, Lower cutaneous nerve of arm and the Posterior cutaneous nerve of forearm. The Superficial branch of the radial nerve is entirely cutaneous and supplies the skin on the dorsum of the wrist, the lateral dorsal surface of the hand, the thumb and two and a half fingers as far as the distal interphalangeal joints.
motor - triceps, anconeus, brachioradialis, extensor carpi radialis longus and the lateral part of brachialis
Posterior interosseous nerve sensory and motor supply
sensory - This branch has no cutaneous supply
motor - supinator, extensor carpi radialis brevis, extensor digitorum, extensor carpi ulnaris, extensor digiti minimi, extensor indicis, extensor pollicis longus and brevis, and abductor pollicis longus.
Median nerve sensory and motor supply
sensory - The lateral branch supplies the skin on the adjacent sides of the thumb and index finger. The medial branch supplies the skin on the palmar surface of the adjacent sides of the index, middle and ring fingers. There is also a dorsal branch which supplies the dorsal aspect of the distal phalanx and nail bed of the thumb, index, middle and ring fingers.
motor - The nerve supplies pronator teres, flexor carpi radialis, Palmaris longus, and flexor digitorum superficialis. The lateral branch supplies abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and the first lumbrical. The medial branch supplies the second lumbrical. The anterior interosseous nerve supplies flexor pollicis longus, lateral half of flexor digitorum profundus and pronator quadratus.
Ulnar nerve sensory and motor supply
sensory - The Dorsal branch of the ulnar nerve supplies skin on the dorsum of the hand and dorsal surfaces of the medial one and a half fingers little and ring fingers). The Superficial branch of the ulnar nerve supplies the skin on the medial side of the palm of the hand and the palmar surface of the little and adjacent side of the ring finger.
motor - The ulnar nerve supplies Flexor carpi ulnaris and the medial part of flexor digitorum profundus. The Superficial branch of the ulnar nerve supplies Palmaris brevis. The deep branch of the ulnar nerve supplies abductor digiti minimi, flexor digiti minimi, opponens digiti minimi (hypothenar muscles), medial 2 lumbricals, all the interossei, and adductor pollicis.
