Lower Limb Neurological Examination
Lower limb neurological examination is essential for evaluating lumbar spine pathology. Examiners expect systematic testing of key myotomes (L2-S1), dermatomes, reflexes, and identification of red flags for cauda equina syndrome. Always include gait assessment.
Quick Reference One-Pager
Key Myotomes
- L2: Hip flexion
- L3: Knee extension
- L4: Ankle dorsiflexion
- L5: Great toe extension (EHL)
- S1: Ankle plantarflexion, eversion
Key Dermatomes
- L2: Anterior thigh
- L3: Medial knee
- L4: Medial calf
- L5: Dorsum of foot, first web space
- S1: Lateral foot, sole
Key Reflexes
- L3-4: Knee jerk (patellar)
- S1: Ankle jerk (Achilles)
- Note: L5 has no reliable reflex
Red Flags (Cauda Equina)
- Bilateral leg symptoms
- Saddle anesthesia (S2-4)
- Bladder/bowel dysfunction
- Progressive weakness
Systematic Approach
Examination Framework
Components:
- Gait: Essential first step
- Motor: Tone, power, bulk
- Sensory: Light touch, pinprick
- Reflexes: Knee jerk, ankle jerk, Babinski
- Straight leg raise: Nerve root tension
Key Principle: The lower limb examination must include cauda equina screening in any patient with lumbar symptoms.
Gait Assessment
Gait Patterns
Normal Gait Phases:
- Heel strike → Stance → Toe-off → Swing
Abnormal Patterns:
Foot Drop Gait (L5/Peroneal):
- High-stepping gait
- Slapping foot on ground
- Cannot heel walk
Trendelenburg Gait (L5/Hip Abductors):
- Pelvis drops on swing side
- Trunk lurches to stance side
Antalgic Gait:
- Short stance phase on painful side
- Non-neurological but important
Spastic Gait (UMN):
- Stiff, circumduction
- Scissors gait
Special test
Heel Walking
Test L4-L5 (ankle dorsiflexors)
Technique
- 1Ask patient to walk on heels for 5-10 steps
- 2Observe for foot drop or difficulty
Positive Sign
Inability to maintain heel walking
Indicates
L4-L5 weakness (tibialis anterior, EHL)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Toe Walking
Test S1-S2 (ankle plantarflexors)
Technique
- 1Ask patient to walk on tiptoes for 5-10 steps
- 2Observe for difficulty or asymmetry
Positive Sign
Inability to maintain toe walking or asymmetry
Indicates
S1-S2 weakness (gastrocnemius, soleus)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Motor Examination
Inspection
Look For:
- Muscle wasting (compare sides)
- Fasciculations
- Trophic changes
- Foot drop posture
Key Areas:
- Quadriceps bulk (L3-4)
- Tibialis anterior (L4-5)
- Calf muscles (S1-2)
- Small muscles of foot
Myotomal Testing
- movement
- Hip flexion
- muscle
- Iliopsoas
- position
- Sitting
- instruction
- Lift thigh off bed against my hand
- movement
- Knee extension
- muscle
- Quadriceps
- position
- Sitting
- instruction
- Straighten knee against my resistance
- movement
- Ankle dorsiflexion
- muscle
- Tibialis anterior
- position
- Supine
- instruction
- Pull foot up toward you
- movement
- Great toe extension
- muscle
- EHL
- position
- Supine
- instruction
- Pull big toe up against my finger
- movement
- Ankle plantarflexion
- muscle
- Gastrocnemius
- position
- Supine/standing
- instruction
- Push foot down (or single heel raise)
- movement
- Ankle eversion
- muscle
- Peronei
- position
- Supine
- instruction
- Turn foot outward against resistance
Key Root Level Tests:
- L4: Ankle dorsiflexion + knee jerk
- L5: EHL extension (big toe up) + NO reliable reflex
- S1: Ankle plantarflexion + ankle jerk
Common Disc Levels:
- L4-5 disc → L5 root compression
- L5-S1 disc → S1 root compression
Sensory Examination
Dermatomes
Key Testing Points:
- L2: Anterior thigh (mid-thigh)
- L3: Medial knee
- L4: Medial calf/malleolus
- L5: First web space (dorsum)
- S1: Lateral foot/little toe
Testing Technique:
- Light touch first
- Pinprick if abnormality suspected
- Work from abnormal to normal area
- Compare sides systematically
Saddle Sensation (S2-S4)
Critical for Cauda Equina:
- Perianal region
- Posterior thigh
- Genitalia
Testing:
- "Is the feeling in your bottom area normal?"
- Pinprick perianal if concern
- Document anal tone if indicated
Red Flag: Reduced perianal sensation = suspected cauda equina until proven otherwise.
Reflexes
Special test
Knee Jerk (Patellar Reflex)
Test L3-L4 nerve roots
Technique
- 1Patient sitting with legs hanging or supine with knee supported in flexion
- 2Tap patellar tendon directly
- 3Observe quadriceps contraction and knee extension
Positive Sign
Absent or diminished = L3-4 radiculopathy; Increased = UMN lesion
Indicates
L3-L4 reflex arc integrity
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Ankle Jerk (Achilles Reflex)
Test S1-S2 nerve roots
Technique
- 1Dorsiflex ankle slightly to stretch Achilles
- 2Tap Achilles tendon
- 3Observe plantarflexion of foot
Positive Sign
Absent or diminished = S1 radiculopathy; Increased = UMN lesion
Indicates
S1-S2 reflex arc integrity
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Babinski Sign (Plantar Response)
Test for upper motor neuron lesion
Technique
- 1Stroke lateral plantar surface from heel to toes
- 2Continue across ball of foot medially
- 3Observe great toe response
Positive Sign
Extension (dorsiflexion) of great toe ± fanning of other toes
Indicates
Upper motor neuron lesion (corticospinal tract dysfunction)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Reinforcement (Jendrassik Maneuver)
When Reflex Appears Absent:
- Patient interlocks fingers and pulls apart
- Or clenches teeth
- Repeat reflex testing during maneuver
Interpretation:
- Present with reinforcement = diminished but present
- Absent even with reinforcement = truly absent
Nerve Root Tension Signs
Special test
Straight Leg Raise (SLR)
Detect L5-S1 root irritation
Technique
- 1Patient supine, relaxed
- 2Lift leg by heel with knee extended
- 3Note angle at which radicular pain occurs
Positive Sign
Radicular pain (below knee) at less than 70°
Indicates
L4, L5, or S1 nerve root irritation (usually disc herniation)
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Crossed SLR (Well Leg Raise)
Detect large disc herniation
Technique
- 1Perform SLR on unaffected leg
- 2Observe for pain in affected leg
Positive Sign
Pain in affected leg when raising unaffected leg
Indicates
Large, axillary disc herniation with significant nerve root compression
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Special test
Femoral Stretch Test
Detect L2-L4 root irritation
Technique
- 1Patient prone or lateral
- 2Flex knee to 90°
- 3Extend hip while knee remains flexed
Positive Sign
Pain in anterior thigh (femoral nerve distribution)
Indicates
Upper lumbar (L2, L3, L4) nerve root irritation
Diagnostic Accuracy
Ability to detect true positives
Ability to exclude false positives
Cauda Equina Screening
Cauda Equina Red Flags - MUST ASK:
- Bladder dysfunction: Retention, incontinence, reduced awareness
- Bowel dysfunction: Incontinence, constipation
- Saddle anesthesia: Numbness around perineum
- Sexual dysfunction: Impotence, reduced sensation
- Bilateral leg symptoms: Weakness or numbness both legs
- Progressive weakness: Getting worse rapidly
If ANY present: URGENT MRI and surgical assessment
Cauda Equina Examination
Sensory:
- Test perianal sensation (S2-4)
- Compare both sides
- Test genital sensation if appropriate
Motor:
- Anal tone (digital rectal exam if indicated)
- Bilateral lower limb power
Reflexes:
- Bulbocavernosus reflex
- Anal wink
Post-void Residual:
- Bladder scan if retention suspected
- Greater than 200mL concerning
Pattern Recognition
L4 Radiculopathy:
- Motor: Weak ankle dorsiflexion, knee extension
- Sensory: Medial calf/malleolus
- Reflex: Reduced knee jerk
Common Cause: L3-4 disc herniation
- slr
- May be positive
- femoralStretch
- Positive
- kneeJerk
- Reduced
- ankleJerk
- Normal
- motor
- Ankle DF, knee extension
- slr
- Positive
- femoralStretch
- Negative
- kneeJerk
- Normal
- ankleJerk
- Normal
- motor
- EHL, ankle DF, hip abduction
- slr
- Positive
- femoralStretch
- Negative
- kneeJerk
- Normal
- ankleJerk
- Reduced
- motor
- Ankle PF, eversion
Upper vs Lower Motor Neuron
- lmn
- Reduced (flaccid)
- umn
- Increased (spastic)
- lmn
- Weakness in specific myotome
- umn
- Pyramidal pattern weakness
- lmn
- Reduced or absent
- umn
- Increased (hyperreflexia)
- lmn
- Absent
- umn
- May be present
- lmn
- Flexor (normal)
- umn
- Extensor (upgoing)
- lmn
- Present
- umn
- Late/minimal
- lmn
- May be present
- umn
- Absent
Summary Presentation
“45-year-old man with right leg pain radiating from buttock to foot, worse on coughing.”
Examination Sequence
Systematic Approach
- Gait: Walking, heel walking, toe walking
- Standing: Romberg, single leg stance
- Supine inspection: Wasting, fasciculations
- Tone: Hip, knee, ankle bilaterally
- Power: L2-S1 myotomes bilaterally
- Sensation: L2-S1 dermatomes, saddle area
- Reflexes: Knee jerk, ankle jerk, Babinski
- SLR: Both legs, note angle and symptoms
- Femoral stretch: If upper lumbar suspected
- Cauda equina screen: Ask about bladder/bowel/saddle
Examiner Tips
Do
- Start with gait assessment (heel and toe walking)
- Know key myotomes (L4 ankle DF, L5 EHL, S1 ankle PF)
- Always check for cauda equina red flags
- Use reinforcement before calling reflex absent
- Present as a root level pattern
Don't
- Miss saddle anesthesia testing
- Confuse dermatomal and peripheral nerve patterns
- Forget that L5 has no reliable reflex
- Skip SLR in lumbar radiculopathy
- Forget that L4-5 disc compresses L5 root (not L4)