Upper Limb Peripheral Nerve Examination
Peripheral nerve examination requires knowledge of individual nerve motor and sensory territories. Examiners expect you to differentiate between median, ulnar, and radial nerve lesions based on examination findings, and to localize the level of injury (high vs low lesion).
Quick Reference One-Pager
Median Nerve
- Motor: LOAF (Lumbricals 1-2, Opponens, APB, FPB superficial)
- High lesion adds: FDS, FDP (IF), FCR, PT, PQ
- Sensory: Palmar lateral 3.5 digits
- Test: OK sign, opposition, pulp of index
Ulnar Nerve
- Motor: All intrinsics EXCEPT LOAF
- High lesion adds: FCU, FDP (RF, SF)
- Sensory: 1.5 digits ulnar (palmar + dorsal)
- Test: Finger abduction, Froment's, little finger pulp
Radial Nerve
- Motor: All extensors (wrist, fingers, thumb)
- High lesion adds: Triceps
- Sensory: First dorsal web space
- Test: Wrist drop, finger extension, thumb retropulsion
Injury Levels
- High: Above elbow
- Low: At wrist/hand
- Pattern differs based on level
Median Nerve
Muscles Supplied:
At/Below Wrist (LOAF):
- Lumbricals 1 and 2
- Opponens pollicis
- Abductor pollicis brevis (APB)
- Flexor pollicis brevis (superficial head)
Above Wrist (Anterior Interosseous - AIN):
- Flexor pollicis longus (FPL)
- Flexor digitorum profundus (index and middle)
- Pronator quadratus
In Forearm (High Lesion):
- Pronator teres
- Flexor carpi radialis
- Palmaris longus
- Flexor digitorum superficialis
- Above plus AIN muscles
Special test
Median Motor Testing - Opposition
Test APB and opponens pollicis
Technique
- 1Ask patient to touch thumb tip to little finger tip
- 2Thumb should rotate (not just adduct)
- 3Resist patient trying to maintain position
Positive Sign
Weak or absent opposition
Indicates
Median nerve motor deficit (LOAF muscles)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
OK Sign Test
Test anterior interosseous nerve function
Technique
- 1Ask patient to make 'OK' sign
- 2Index and thumb should form a circle with flexed DIP/IPJ
Positive Sign
Triangle sign (flat index DIP, flat thumb IPJ) instead of circle
Indicates
Anterior interosseous syndrome - FPL and index FDP weakness
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Ulnar Nerve
Muscles Supplied (All Intrinsics Except LOAF):
Hand Muscles:
- Interossei (all 4 dorsal, all 3 palmar)
- Lumbricals 3 and 4
- Adductor pollicis
- Flexor pollicis brevis (deep head)
- Hypothenar muscles (ADM, ODM, FDM)
Forearm (High Lesion Only):
- Flexor carpi ulnaris (FCU)
- Flexor digitorum profundus (ring and little fingers)
Special test
Froment's Sign
Test adductor pollicis (ulnar nerve)
Technique
- 1Patient grips paper between thumb and side of index finger
- 2Pull paper away
- 3Observe thumb position
Positive Sign
Flexion of thumb IPJ (using FPL instead of weak adductor pollicis)
Indicates
Ulnar nerve palsy with adductor pollicis weakness
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Finger Abduction Test
Test dorsal interossei (ulnar nerve)
Technique
- 1Patient spreads fingers apart (abduction)
- 2Examiner attempts to push fingers together
Positive Sign
Weakness of finger abduction compared to other side
Indicates
Ulnar nerve palsy - dorsal interosseous weakness
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Wartenberg Sign
Test ulnar nerve function
Technique
- 1Patient extends fingers straight
- 2Observe position of little finger
Positive Sign
Little finger abducted, cannot be held adducted
Indicates
Ulnar nerve palsy - weak third palmar interosseous
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Radial Nerve
Muscles Supplied:
In Arm (High Lesion):
- Triceps
- Brachioradialis
- ECRL (may be spared as branch early)
In Forearm:
- ECRB
- Supinator
- Extensor digitorum communis
- Extensor digiti minimi
- Extensor carpi ulnaris
- Abductor pollicis longus
- Extensor pollicis brevis
- Extensor pollicis longus
- Extensor indicis
Posterior Interosseous Nerve (PIN):
- Pure motor branch
- All extensors below supinator
Special test
Wrist Drop Test
Test radial nerve function
Technique
- 1Ask patient to extend wrist against gravity
- 2Arms out, palms facing floor
- 3Compare sides
Positive Sign
Wrist drops, cannot extend against gravity
Indicates
High radial nerve palsy
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Finger Extension Test
Test PIN or radial nerve
Technique
- 1Hold wrist in neutral (supported)
- 2Ask patient to extend MCP joints of fingers
Positive Sign
Cannot extend fingers at MCP joints
Indicates
Radial nerve (high) or PIN (low) lesion
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
EPL Test (Retropulsion)
Test extensor pollicis longus
Technique
- 1Place palm flat on table
- 2Ask patient to lift thumb straight up off surface
Positive Sign
Cannot lift thumb off table
Indicates
EPL rupture or radial nerve/PIN lesion
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Musculocutaneous Nerve
Anatomy and Function
Motor:
- Biceps brachii (main elbow flexor and supinator)
- Brachialis
- Coracobrachialis
Sensory:
- Lateral cutaneous nerve of forearm
- Lateral forearm sensation
Clinical Features of Lesion:
- Weak elbow flexion (biceps and brachialis)
- Weak supination
- Numbness lateral forearm
- Absent biceps reflex
Distinguishing Lesion Levels
- highLesion
- Hand of Benediction, no FPL/index FDP
- lowLesion
- Thenar wasting, weak opposition only
- highLesion
- Less claw, no FCU/ulnar FDP
- lowLesion
- Worse claw, dorsal sensation may be spared
- highLesion
- Wrist drop + finger drop
- lowLesion
- Finger drop only (PIN), or sensory only (superficial)
Quick Differentiation:
- Can't make fist (IF, MF) = Median (high)
- Can't spread fingers = Ulnar
- Can't extend wrist/fingers = Radial
- Can't flex elbow = Musculocutaneous
Sensory Key Points:
- Index pulp = Median
- Little finger pulp = Ulnar
- First web space dorsum = Radial
Combined Lesions
Brachial Plexus Patterns
Upper Trunk (Erb's C5-6):
- Weak shoulder abduction, external rotation
- Weak elbow flexion
- Waiter's tip posture
Lower Trunk (Klumpke's C8-T1):
- Intrinsic hand weakness
- Ulnar sensory loss
- May have Horner's syndrome
Posterior Cord:
- Radial + axillary nerves
- Wrist drop + weak shoulder abduction
Summary Presentation
“35-year-old man presents 3 months after humeral shaft fracture with inability to extend wrist.”
Examination Sequence
Systematic Approach
- Inspection: Wasting, deformity, trophic changes
- Median motor: Opposition, APB, OK sign
- Ulnar motor: Finger abduction, Froment's, Wartenberg
- Radial motor: Wrist extension, finger extension, EPL
- Median sensory: Index finger pulp
- Ulnar sensory: Little finger pulp, dorsal (check level)
- Radial sensory: First dorsal web space
- Reflexes: Biceps, triceps
- Compare sides: Every finding
- Localize level: High vs low based on pattern
Examiner Tips
Do
- Know key muscles for each nerve (LOAF for median)
- Test sensory at key points (index, little, 1st web)
- Distinguish high from low lesions
- Know Froment's sign technique and meaning
- Compare systematically with other side
Don't
- Confuse dermatomal with peripheral nerve pattern
- Miss the ulnar paradox concept
- Forget to test triceps in radial nerve (localizes level)
- Miss the dorsal cutaneous branch sparing in wrist-level ulnar
- Overlook PIN syndrome (motor only, no sensory loss)