Dermatome / Myotome / Reflex Reference

Vertex of skull / top of head

Neck flexion (rectus capitis)

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Posterior scalp, upper neck

Neck flexion / extension

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Lateral neck, angle of jaw

Neck lateral flexion (scalenes)

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Shoulder cape / upper trapezius area

Shoulder elevation (trapezius, levator scapulae)

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Lateral upper arm (regimental badge area)

Shoulder abduction (deltoid), elbow flexion (biceps)

Biceps (C5–C6)

Lateral forearm, thumb, index finger

Wrist extension (ECRL/ECRB), elbow flexion

Brachioradialis (C6), Biceps (C5–C6)

Middle finger, posterior forearm

Elbow extension (triceps), wrist flexion

Triceps (C7)

Ring & little finger, medial forearm

Finger flexion (FDP), intrinsics

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Medial forearm, medial elbow

Finger abduction / adduction (interossei)

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Inner upper arm, axilla

Intercostals (T1–T12)

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Upper chest / back (band-like)

Intercostals

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Mid-chest / epigastric region

Intercostals, upper abdominals

Upper abdominal (T7–T9)

Umbilicus level

Abdominals

Mid-abdominal (T10)

Lower abdomen / groin

Lower abdominals

Lower abdominal (T11–T12)

Groin / upper medial thigh

Hip flexion (iliopsoas, partial)

Cremasteric (L1–L2)

Anterior thigh (upper)

Hip flexion (iliopsoas)

Cremasteric (L1–L2)

Anterior thigh (lower), medial knee

Knee extension (quadriceps)

Patellar (L3–L4)

Medial lower leg, medial foot

Ankle dorsiflexion (tibialis anterior)

Patellar (L3–L4)

Lateral lower leg, dorsum of foot, great toe

Great toe extension (EHL), hip abduction

Medial hamstring (L5)

Posterior calf, lateral foot, little toe

Plantarflexion (gastrocnemius/soleus), hip extension

Achilles (S1–S2)

Posterior thigh, perineum

Knee flexion (hamstrings)

Achilles (S1–S2)

Medial thigh, perineum (saddle)

Bladder / bowel sphincters

Bulbocavernosus

Perineum, perianal region

External anal sphincter

Anal wink