Upper Limb, Nerve Injury - NEET PG Orthopedics

Upper limb injuries are common, and orthopedic surgeons frequently treat these injuries. Knowledge of upper limb anatomy and orthopedics is essential to diagnose and manage such injuries.

In this blog we’ll cover sensory distribution of upper limb, seddon classification for nerve injuries, brachial plexus palsy, and compression neuropathy. 

SENSORY DISTRIBUTION OF UPPER LIMB

Tip of index finger - Median nerve

• Tip of little finger - Ulnar nerve
• Over dorsum of hand, 1st web space -Radial nerve

SEDDON CLASSIFICATION FOR NERVE INJURIES

Neuropraxia

• Physiological block in nerve conduction
• 100% recovery
• One moment
• Tinel sign negative

Axonotmesis

• Damage to axon sheath
• Recovery - Motor march (proximal to distal)
• Tinel sign positive & progressive - marks recovery of nerve at the rate of 1 mm/day

Neurotmesis

• Complete nerve transection
• Tinel sign positive & static
• Does not recover without surgical intervention

AXILLARY NERVE

• Damaged by
  • Shoulder dislocation
  • Fracture of upper end of humerus
  • Injection into deltoid muscle

Clinical Features

• Regimental badge area (area at upper end of humerus) - sensations are impaired

ULNAR NERVE

Interosseous muscles of hand

• Palmar interossei – Adduction (PAD)
• Dorsal interossei – Abduction (DAB)
• They are supplied by Ulnar nerve

Tests for Ulnar Nerve Injury

Card Test

For Palmar Interossei

• Holding card between the fingers (adduction) & trying to pull the card
• If they are able to hold it, means palmar interossei is functioning 
• If not, it means ulnar nerve palsy 

Book Test/Froment Sign

Ask the patient to hold book between his thumb & index finger

• Adductor pollicis is supplied by ulnar nerve
• If they hold the book by flexing thumb (Froment sign)
• Flexion is due to flexor pollicis longus- supplied by AIN, branch of Median nerve (spared in ulnar nerve injury)

Wartenberg sign

Abducted 5^th finger

Igawa test

• Middle finger has only dorsal interossei, can move middle finger to either side (abduction)

MEDIAN NERVE

Tests for median nerve

Pointing index

If you ask the patient to make a fist, the first two fingers do not flex in median nerve palsy.

• Index finger is not flexed at PIP & DIP
• This is called as pointing index
• Also known as Benediction test, Oschner clasp test

Benediction test or Pope's attitude

Oschner clasp test

Pen test

If you keep the pen above the palm and as the patient to touch the pen, it is called as pen test

• To check abductor pollicis brevis

Ape thumb deformity

• Loss of thenar eminence
• Thumb in same plane as palm (Ideally it is anteriorly)

Kiloh-Nevin sign

• Check for anterior interosseous nerve (AIN), branch of median nerve 
• Sign of Appreciation - WOW sign (created by flexion of index finger and thumb)

CLAW HAND

• Lumbricals - 4 in no.
• Makes a ‘L’ in hand
• Medial 2 lumbricals - supplied by Ulnar nerve
• Lateral 2 lumbricals - supplied by Median nerve

Action of lumbricals

• Flexion of metacarpophalangeal joint
• Extension of interphalangeal joint

Paralysis of lumbricals

• Causes Claw Hand
• Hyperextension of metacarpophalangeal joint
• Flexion of interphalangeal joint

Management

• Knuckle bender splint used for Ulnar nerve > Median nerve 

Also Read: Hamstring Injury: Causes, Symptoms, Risk Factors, Diagnosis, Treatment, Prevention and Complications

RADIAL NERVE

Relation with Humerus

• Travels along spiral groove
• At lower 1/3^rd level, it pierces lateral intermuscular septum & comes anteriorly (most common area of involvement)

It divides into -

1. Posterior interosseous nerve (PIN)
   • Pure motor nerve
   • Supplies finger extensors
   • Injury - only finger drop, no sensory loss

2. Superficial radial nerve
   • Supplies dorsum of 1st web space

Clinical features 

• Wrist drop  
  • Paralysis of ECRL & ECRB
  • Sensory loss over dorsum of 1^st web space

• Finger drop
  • Due to injury to PIN.
  • No sensory loss

Saturday night palsy/Crutch palsy/Honeymoon palsy

Radial nerve is compressed against bone d/t sustained pressure

Radial nerve injury

Management

Cock up splint 

MANAGEMENT IN NERVE INJURY

• Neuropraxia – 100% recovery 
• Radial nerve is the most commonly damaged nerve
• It has the best prognosis for recovery 

Orthopedics Related Articles:

BRACHIAL PLEXUS PALSY

Erb's palsy

• Common
• Better prognosis
• Injury to upper trunk (C5, C6)
• Movements lost
  • Flexion of elbow
  • Abduction of shoulder
  • External rotation of shoulder

Clinical features

• Waiter tip deformity

Klumpke's palsy

• Injury to lower trunk (C8, T1)

Clinical features  

• Claw hand
• Horner syndrome (may/may not be present)
• Poor prognosis

COMPRESSION NEUROPATHY

Carpal tunnel syndrome

• Median nerve is involved at wrist
• MC cause - Idiopathic

Syndrome and nerves involved

• Carpal tunnel syndrome - Median nerve
• Pronator syndrome - Median nerve
• Cubital tunnel syndrome - Ulnar nerve
• Guyon canal syndrome - Ulnar nerve

Also Read: Anterior Cruciate Ligament Injury: Causes, Symptoms, Types, Risk Factors, Diagnosis, Treatment, Prevention and Complication

Tests for Carpel tunnel syndrome

1. Phalen test

2. Reverse Phalen test

Thoracic outlet syndrome

• Involvement of C8 & T1
• T1 is more commonly involved 

Tests for Thoracic outlet syndrome

1. Adson test
   • Abduction and hyperextension of shoulder  

2. Wright test
   • Abduction and hyperextension

3. Roos test
   • Abduction and hyperextension

TEST FOR ARTERIAL BLOOD SUPPLY ON HAND

Allen test

• To check patency of radial & ulnar artery
• 1^st press both arteries → make a fist
• Palm will turn white
• Release radial artery palm will turn red if it is patent
• Repeat the same process
• Now release ulnar artery palm will turn red if it is patent

Also Read: Shin Splits: Causes, Symptoms, Risk Factors, Diagnosis, Treatment and Prevention

Practice Questions

Q. Identify the splint?

1. Cock up splint
2. Knuckle bender splint
3. Dynamic finger splint
4. Sugar tongs

Ans - A

Q. Middle finger extension test is useful for all except?

1. PIN palsy
2. Radial tunnel syndrome
3. Tennis elbow
4. Multifocal motor neuropathic disorder

Ans - D

Q. A patient can't extend his wrist but he has no sensory loss, after he has met with an accident. Level at which the affected nerve got injured is?

1. Spiral groove of humerus
2. Head of radius
3. Near medial epicondyle
4. Surgical neck of humerus

Ans – A

Previous Year Question

Q. The Nerve related to medial epicondyle is? (FMGE -Dec - 2020)

A.  Median Nerve

B.  Ulnar nerve

C.  AIN 

D.  PIN 

Q. Hyperextension at MCP joint and flexion at IP joint occurs due to involvement of which muscle? (NEET - Jan - 2020)

A.  Lumbricals

B. Palmar interossei

C. Dorsal interossei 

D.  Adductor pollicis 

Q. Most specific test for Carpel tunnel syndrome? (AIIMS - June - 2020)

A.  Cozen test

B   Phalen test

C.  Durkan test 

D.  Tourniquet test 

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