Sensory Examination of The Spine – Key Sensory Points In ASIA Score

ASIA Score -Distribution of Sensory Dermatomes

A dermatome is a patch of skin that is innervated by a given spinal cord level. While each spinl nerve has a specific dermatomal point for testing that nerve. The image above is from American Spinal Injury  Association and outlines the distribution of different spinal nerves which can be used for testing them and conducting a spinal examination

it must be noted that the outline is supposed to be rough guide and there may be overlaps of different dermatones especially in the transitional areas. Moreover,  the dermatomes can expand or contract following an injury, depending on plasticity of the spinal cord.

Key Sensory Points

ASIA names key sensory points which are easy to measure.

C2 to C4

• C2 dermatome covers the occiput and the top part of the neck.
• C3 covers the lower part of the neck to the clavicle bone.
• C4 covers the area just below the clavicle.

C5 to T1

These dermatomes are all situated in the arms.

• C5 covers the lateral arm at and above the elbow.
• C6 covers the forearm and the radial  side of the hand.
• C7 is the middle finger,
• C8 is the lateral aspects of the hand
• T1 covers the medial side of the forearm.

T2 to T12

• T2 covers the axillary and chest region and upper medial aspect of arm.
• T3 to T12 covers the chest and back to the hip girdle.
  • The nipples are situated in the middle of T4.
  • T10 is situated at the umbilicus.
  • T12 ends just above the hip girdle.

L1 to L5

• L1 innervates hip girdle and groin area
• L2 and 3 cover the front part of the thighs.
• L4 and L5 cover medial and lateral aspects of the lower leg.

S1 to S5

• S1 covers the heel and the middle back of the leg.
• S2 covers the back of the thighs.
• S3 cover the medial side of the buttocks and S4-5 covers the perineal region.
• S5 forms  the lowest dermatome and represents the skin immediately at and adjacent to the anus.