Note: C1 doesn’t have a sensory branch
For the purpose of making learning easier, we divide the remaining dermatomal segments into 4 groups which will be accompanied by analogies and mnemonics.
C2-C4
These supply the “hooded cape” region.
- C2: hood region abutting the trigeminal distribution
- C3: upper neck
- C4: lower neck and shoulders
C5-T1
Dermatome C7 extends to the middle finger and divides dermatomes C5 and C6 (lateral) from C8 through T1 (medial).
- C5: lateral aspect of arm
- C6: lateral aspect of forearm and hand
- C7: middle finger and ray
- C8: medial aspect of hand
- T1: medial aspect of forearm
T2-L1
These are present over the trunk and progresses sequentially from top to bottom. Remembering important landmarks is helpful.
- T4: nipples
- T10: umbilicus (0 looks like umbilicus)
- L1: inguinal area
S2-S5
2, 3, 4, 5, stand on S1, lie on S2, sit on S3, wipe S4/S5
- Slap thigh lateral then medial: L2 then L3
- Slap lower legs medial then lateral: L4 then L5
- Stand on sole of foot: S1
- Lie on back of thigh and calf: S2
- Sit on buttocks: S3
- Wipe perianal area: S4, S5
Also note that: L5 is for Large toe and S1 is for Small toe