Learn / Level 1
Dermatomes
Map each spinal level to the skin it supplies. Start in Reference to look, then switch to Find it and Name it to drill. Narrow the drill to one limb while you're learning it.
Hover a region for its landmark. Click one to pin it in the table. The map is schematic — real dermatomes overlap and vary between references.
Landmarks worth memorizing
| Level | Landmark | Cutaneous nerve(s) | Notes |
|---|---|---|---|
| C2 | Posterior scalp / occiput | Greater occipital n. (C2 dorsal ramus); lesser occipital n. (cervical plexus) | Greater occipital nerve territory. C1 has no dermatome. |
| C3 | Neck (front and back) | Transverse cervical n. & lesser occipital n. (cervical plexus); C3 dorsal ramus posteriorly | Also the skin over the angle of the jaw region below V3. |
| C4 | Shoulder tops — the 'cape' | Supraclavicular nn. (cervical plexus, C3–C4) | Supraclavicular nerves. Shoulder-tip pain from diaphragmatic irritation is referred here (phrenic C3–C5). |
| C5 | Lateral upper arm over the deltoid | Superior lateral cutaneous n. of arm (axillary n.) | Axillary nerve (superior lateral cutaneous) territory — 'regimental badge'. |
| C6 | Thumb and lateral forearm | Lateral antebrachial cutaneous n. (musculocutaneous n.); superficial branch of radial n. (dorsal thumb) | Mnemonic: make a '6' with thumb and index finger. |
| C7 | Middle finger | Median n. digital branches (palmar); superficial radial n. (dorsal) | The 'middle' of the hand. |
| C8 | Little finger and medial hand | Ulnar n. — palmar & dorsal digital branches | Ulnar nerve territory overlaps here. |
| T1 | Medial forearm | Medial antebrachial cutaneous n. (medial cord) | Medial antebrachial cutaneous nerve. |
| T2 | Medial upper arm and axilla | Intercostobrachial n. (T2 intercostal) medially; T2 anterior cutaneous branch on the chest | Intercostobrachial nerve. Also the band just below the clavicle on the chest. |
| T3 | Chest band below T2 | T3 intercostal n. (anterior & lateral cutaneous branches) | |
| T4 | Nipple line | T4 intercostal n. | 'T4 at the teat pore'. |
| T5 | Band between nipple and xiphoid | T5 intercostal n. | |
| T6 | Xiphoid process | T6 intercostal n. | |
| T7 | Band below xiphoid | T7 intercostal n. | |
| T8 | Costal margin band | T8 intercostal n. | |
| T9 | Band above umbilicus | T9 intercostal n. | |
| T10 | Umbilicus | T10 intercostal n. | 'T10 at the belly butt-ten'. Appendix pain refers here early. |
| T11 | Band below umbilicus | T11 intercostal n. | |
| T12 | Just above the inguinal ligament / pubic region | Subcostal n. (T12) | |
| L1 | Inguinal ligament | Iliohypogastric & ilioinguinal nn. (lumbar plexus) | 'L1 is IL (Inguinal Ligament)'. Ilioinguinal & iliohypogastric. |
| L2 | Anterior upper thigh | Lateral femoral cutaneous n. (lateral); anterior cutaneous branches of femoral n.; genitofemoral n. (upper medial) | |
| L3 | Anterior lower thigh and medial knee | Anterior cutaneous branches of femoral n.; obturator n. (medial thigh) | 'L3 — knee'. |
| L4 | Medial leg, medial malleolus, great toe | Saphenous n. (femoral n.) — medial leg & malleolus; deep fibular n. (1st web space) | 'Down on all fours (L4)' — kneel: the medial leg/knee touches the floor. |
| L5 | Lateral leg and dorsum of the foot | Superficial fibular n. (dorsum); lateral sural cutaneous n. (lateral leg) | Foot-drop territory: dorsum of the foot and toes 1–3 dorsally. |
| S1 | Lateral foot, little toe, heel, posterior calf | Sural n. (lateral foot & heel); tibial n. calcaneal branches; lateral plantar n. | 'S1 — the small one (little toe)'. Achilles reflex. |
| S2 | Posterior thigh and popliteal fossa, medial calf strip | Posterior femoral cutaneous n. (posterior thigh); sural n. (medial calf strip) | |
| S3–S5 | Perianal / perineal 'saddle' | Pudendal n. (S2–S4) & perforating cutaneous / anococcygeal nn. | Saddle anesthesia = cauda equina red flag. |