Nerve injuries are important short cases for clinical examinations and OSCE for medical students
Radial Nerve
Branches from Posterior Cord of Brachial plexus( Infront of subscapularis)
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Anterior to lattismus dorsi
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Through triangular space with profundus brachii artery
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Enters upper arm between long head of triceps and medial head of triceps
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Spiral groove
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Courses laterally and pierces the lateral intermuscular septum
(122mm above lateral epicondyle)
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Passes into the anterior compartment
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At the level of the lateral epicondyle, it gives 2 branches
- Deep Posterior Interosseous Nerve (Purely Motor) which enters extensor compartment between 2 heads of supinator (Arcade of fortse) and supplied radial side and dorsal side of the forearm which supplies to
- Superficial group: ECU, ED, EDM
- Deep group: A(bd)PL, EPL, EPB, EI
- The superficial branch of the radial nerve goes deep to the brachioradialis and emerges 5 cm above the wrist between the brachioradialis and ECR which goes towards the anatomical snuffbox to supply the dorsum of the hand
Median Nerve(C6-T1)
The medial and lateral cord of the brachial plexus
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The medial side of the arm between biceps brachii and brachialis
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The close relation to the brachial artery
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NO BRANCHES IN THE UPPER ARM
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Cubital fossa (B-A-N)
(Bicep tendon- Artery- Nerve) Lateral to medial
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Passes between 2 heads of pronator teres
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Gives Anterior Interosseous Nerve (AIN)
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In forearm continues (FDS and FDP)
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Emerges just proximal to wrist between FCR and PL
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Passes through the Carpal tunnel
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Divide in hand as recurrent motor branches and sensory branches
- Palmer cutaneous nerve
- Thenar Group
- APB
- FPB
- OP
- 1st and 2nd lumbricals
Ulnar nerve (C8 – T1)
The median cord of the brachial plexus
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Inferior medial to the axillary artery to continue behind the brachial artery over tricep muscle
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Passes straight to the posterior aspect of medial epicondyle in ”ulnar groove” between medial epicondyle and olecranon
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NO BRANCHES IN THE UPPER ARM AND AXILLA
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Passes to the 2 heads of FCU
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Remains deep to FCU overlying FDP muscle accompanied with the ulnar artery
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Passes superficial; emerging beneath FCU and reaches Guyon’s canal at the wrist
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- Deep branches:
- Three hypothenar
- Medial 2 lumbricals
- 7 Interossei
- Adductor pollices
- Deep head of FPB
- Superficial branches:
- Palmer cutaneous branches of the ulnar nerve ( sensation over palm of hand, medial dorsal aspect of hand, and one and a half finger)
- Palmaris brevis muscle
Approach to the short case
While approaching a nerve injury patient certain questions should be answered which is expected from examiner,
Which?
Dominant or Non-dominant
When?
Time elapsed since injury
How?
Mechanism of injury
- Tractional
- Contusion
- Compression
- Laceration
What?
Treatment that patient got
At End the student should answer:
- Nerve Involved
- High/ Low
- Complete/ Incomplete
- Neuropraxia/ Axonotemesis/ Neurotomesis
- Recovering/ Non- recovering
- Management
Eg:
High radial nerve palsy, complete, neurotomesis as per Seddon, no sign of recovery of the non-dominant hand
Look
Site of scar
Ulcers
Smooth/ dryness
Circulatory changes
Temperature
Characteristics of posture in nerve injury
- Radial Nerve- Wrist drop
- Ulnar Nerve- Claw Hand
- Median Nerve – Ape thump
- Combined Median and Ulnar Nerve- Simian thump
Alteration of contour
Loss of muscle bulk
The prominence of bones normally masked by muscle
Muscle and its supply in the forearm and wrist
Median Nerve
Look for PT: Flex the elbow to 30 degrees and ask to pronate the forearm
Look for PQ: Completely flex the elbow and ask to pronate the forearm
APB: Pen test
FCR: Resistance against flexion of the wrist against resistance
Look for FDS, FDP
Bennet ‘O’ Sign: Not able to make O due to paralysis of FPL and FDP
Oschner’s Pointing Index
Ulnar nerve
Card Test: To test Interossei (Palmer ADduction, Dorsal ABduction)
Resistance flexion of the wrist against ulnar deviation: FCU
By abduction of individual muscles: 1st dorsal interossei
Unable to cross the index and middle finger
Pitres-stut test: Abduct the middle finger on either side
Pitres-stut sign 2: Try to make a cone with extended fingers (Not able to do it)
Unable to abduct little finger: ADM
Wartenberg sign: Due to paralyzed ADM there will be the unopposed pull of extensors==> little finger goes into abduction and extension
Jeanes Sign: Paralysis of FPB and A(dd)P-> Loss of key pinch
Smith Sign: Loss of lateral movement in extension due to paralysis of interossei
Forment book Test: Paralysis of A(dd)P= compensated by flexion of the thumb
Duchenne’s Sign: Loss of MCP flexion, Clawing
Bouvier’s maneuver: MCP stabilized in slight flexion: PIP joint extended by extensor tendons
