Radial & Ulnar Nerves

At the end of the lecture, students should be able to: At the end of the lecture, students should be able to: Describe the anatomy of the radial & ulnar nerves regarding: origin, course & distribution. List the branches of the nerves. Describe the causes and manifestations of nerve injury. At the end of the lecture, students should be able to: At the end of the lecture, students should be able to: Describe the anatomy of the radial & ulnar nerves regarding: origin, course & distribution. List the branches of the nerves. Describe the causes and manifestations of nerve injury. Objectives

Origin: Posterior cord of the brachial plexus in the axilla (the largest branch) Supplies: All Muscles of the posterior compartment of the arm & fore arm Origin: Posterior cord of the brachial plexus in the axilla (the largest branch) Supplies: All Muscles of the posterior compartment of the arm & fore arm Radial Nerve

Course In the Arm

It pierces the Lateral Intermuscular septum Descends in front of the Lateral Epicondyle runs forward into the Cubital Fossa Divides into Superficial & Deep branches. It pierces the Lateral Intermuscular septum Descends in front of the Lateral Epicondyle runs forward into the Cubital Fossa Divides into Superficial & Deep branches. Course In the Forearm

Branches: Branches: Arising In The Axilla Cutaneous: Posterior cutaneous nerve of arm. Muscular to: Long & Medial Heads of Triceps. Cutaneous: Posterior cutaneous nerve of arm. Muscular to: Long & Medial Heads of Triceps.

Cutaneous: 1.Lower lateral cutaneous nerve of arm. 2.Posterior cutaneous nerve of forearm. Muscular to: 1.Lateral & Medial heads of triceps. 2.Anconeus. Cutaneous: 1.Lower lateral cutaneous nerve of arm. 2.Posterior cutaneous nerve of forearm. Muscular to: 1.Lateral & Medial heads of triceps. 2.Anconeus. Branches: Branches: Arising In The Spiral Groove

Muscular to: 1.Brachioradialis. 2.Extensor carpi radialis longus. 3.Brachialis. Articular to: Elbow joint Muscular to: 1.Brachioradialis. 2.Extensor carpi radialis longus. 3.Brachialis. Articular to: Elbow joint Branches: Branches: Arising Close to Lateral Epicondyle

SUPERFICIAL BRANCH OF RADIAL NERVE Superficial Branch

Distribution of Superficial Branch The area of skin supplied by the nerve on the dorsum of the hand is variable.

Deep Branch It winds around the neck of the radius, within the supinator muscle, and enters the posterior compartment of the forearm. It is PURELY MOTOR nerve and supplies the extensor muscles in the posterior compartment of the forearm. Extensor carpi radialis brevis. Extensor carpi ulnaris. Supinator. Abductor pollicis longus. Extensor pollicis brevis. Extensor pollicis longus. Extensor indicis. It winds around the neck of the radius, within the supinator muscle, and enters the posterior compartment of the forearm. It is PURELY MOTOR nerve and supplies the extensor muscles in the posterior compartment of the forearm. Extensor carpi radialis brevis. Extensor carpi ulnaris. Supinator. Abductor pollicis longus. Extensor pollicis brevis. Extensor pollicis longus. Extensor indicis.

Summary of Branches of Radial Nerve

In the Axilla: The nerve can be injured by a drunkard falling asleep with one arm over the back of a chair, also by fractures and dislocations of the proximal end of the humerus. The triceps, the anconeus, and the long extensors of the wrist are paralyzed. The patient is unable to extend the elbow & the wrist joints, and the fingers (Wrist Drop) In the Axilla: The nerve can be injured by a drunkard falling asleep with one arm over the back of a chair, also by fractures and dislocations of the proximal end of the humerus. The triceps, the anconeus, and the long extensors of the wrist are paralyzed. The patient is unable to extend the elbow & the wrist joints, and the fingers (Wrist Drop) Radial Nerve Injuries In the Spiral Groove: Injury or fracture of the spiral groove of the humerus, the patient is unable to extend the wrist and the fingers (Wrist Drop). In the Spiral Groove: Injury or fracture of the spiral groove of the humerus, the patient is unable to extend the wrist and the fingers (Wrist Drop).

Injury like a stab wound, results in a variable small area of anesthesia over the dorsum of the hand and lateral three and half fingers up to the base of their proximal phalanges. Injury to the Superficial Branch of the Radial Nerve

Injury to the Deep Branch of the Radial Nerve

Origin: Medial cord of Brachial Plexus. Course in the ARM: Descends along the medial side of the axillary/brachial arteries: Pierces the Medial Intermuscular Septum. Passes Behind the Medial Epicondyle of the humerus. Origin: Medial cord of Brachial Plexus. Course in the ARM: Descends along the medial side of the axillary/brachial arteries: Pierces the Medial Intermuscular Septum. Passes Behind the Medial Epicondyle of the humerus. Ulnar Nerve

Course In the Forearm

Course At the Wrist

In the Forearm:  Muscular to 1 & 1/2 muscles: 1.Flexor Carpi Ulnaris. 2.Medial 1l2 of Flexor Digitorum Profundus.  Articular to Elbow joint.  Cutaneous: 1. Dorsal (posterior) cutaneous: Supplies the skin over the back of Medial side of the hand & Medial 1+1/2 fingers 2. Palmar cutaneous: Supplies the skin over the Medial part of the palm. In the Forearm:  Muscular to 1 & 1/2 muscles: 1.Flexor Carpi Ulnaris. 2.Medial 1l2 of Flexor Digitorum Profundus.  Articular to Elbow joint.  Cutaneous: 1. Dorsal (posterior) cutaneous: Supplies the skin over the back of Medial side of the hand & Medial 1+1/2 fingers 2. Palmar cutaneous: Supplies the skin over the Medial part of the palm. Branches It gives No branches in the arm

1. Muscular: Palmaris Brevis. 2. Cutaneous: Skin over the Palmar aspect of the medial 1+ ½ fingers (including nail beds). 1. Muscular: Palmaris Brevis. 2. Cutaneous: Skin over the Palmar aspect of the medial 1+ ½ fingers (including nail beds). Branches of Superficial Terminal Branch

Muscular branches to: 1.Hypothenar Eminence. 2.All Interossei (Palmar & Dorsal). 3.3 rd & 4 th Lumbricals. 4.Adductor pollicis. Articular: To Carpal joints. Muscular branches to: 1.Hypothenar Eminence. 2.All Interossei (Palmar & Dorsal). 3.3 rd & 4 th Lumbricals. 4.Adductor pollicis. Articular: To Carpal joints. Branches of Deep Terminal Branch

Summary of branches of Ulnar Nerve

Ulnar Nerve Injury At the Elbow: Atrophy of Ulnar side of forearm. Flexion of the wrist with Abduction. Claw hand. Wasting of Hypothenar Eminence. At the Elbow: Atrophy of Ulnar side of forearm. Flexion of the wrist with Abduction. Claw hand. Wasting of Hypothenar Eminence. At the wrist: Claw Hand. Wasting of Hypothenar Eminence. At the wrist: Claw Hand. Wasting of Hypothenar Eminence.

Lesion of the ulnar nerve at the wrist: Medial Two Lumbricals: Flexes the MCP (metacarpophalangeal joints) of the little and ring fingers.Extends the IP (interphalangeal joints) of the little and ring fingers Interossei: Abduct and adduct the fingers Hypothenar Muscles: Flex, adduct, and oppose the little finger Adductor Pollicis: Adducts the thumb The key set of muscles that are paralysed are the lumbricals. There is now a loss of flexion at the MCP joint and a loss of extension at the IP joints. This results in the ulnar claw: the MCP joints are hyperextended by unopposed extension from the extensor digitorum, and the IP joints are flexed by unopposed flexion from the flexor digitorum profundus. This only occurs in the little and ring fingers as the lateral two lumbricals are innervated by the median nerve. Lesion of the ulnar nerve at the wrist: Medial Two Lumbricals: Flexes the MCP (metacarpophalangeal joints) of the little and ring fingers.Extends the IP (interphalangeal joints) of the little and ring fingers Interossei: Abduct and adduct the fingers Hypothenar Muscles: Flex, adduct, and oppose the little finger Adductor Pollicis: Adducts the thumb The key set of muscles that are paralysed are the lumbricals. There is now a loss of flexion at the MCP joint and a loss of extension at the IP joints. This results in the ulnar claw: the MCP joints are hyperextended by unopposed extension from the extensor digitorum, and the IP joints are flexed by unopposed flexion from the flexor digitorum profundus. This only occurs in the little and ring fingers as the lateral two lumbricals are innervated by the median nerve. Lesion of the ulnar nerve at the elbow. In addition to the muscles of the hand, these muscles are paralysed: Medial half of Flexor Digitorum Profundus: Flexes the IP joints of the ring and little fingers Flexor Carpi Ulnaris: Flexes and adducts the wrist The ulnar claw will develop as before, but with one key difference. The flexor digitorum profundus is paralysed, and there will not be any flexion of the ring and little fingers. Now the ulnar claw only consists of hyperextension at the MCP joints, giving a less evident claw hand. Lesion of the ulnar nerve at the elbow. In addition to the muscles of the hand, these muscles are paralysed: Medial half of Flexor Digitorum Profundus: Flexes the IP joints of the ring and little fingers Flexor Carpi Ulnaris: Flexes and adducts the wrist The ulnar claw will develop as before, but with one key difference. The flexor digitorum profundus is paralysed, and there will not be any flexion of the ring and little fingers. Now the ulnar claw only consists of hyperextension at the MCP joints, giving a less evident claw hand.

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