This is a very clear depiction of the dermatomes and peripheral nerves supplying sensation to the body.
- Testing sensation:
- Vibration (128Hz tuning fork): dorsal column
- Touch: dorsal column, diffuse ascending fibres, anterolateral tract
- Pain and temperature: anterolateral / spinothalamic tract
- Cortical sensation
- Sensation to pain, vibration intact
- Loss of two-point discrimination: 3mm at the pump of each finger
- Agraphia: inability to recognize numbers / letters drawn on pal with eyes closed
- Stereognosis: inability to identify common objects (e.g. key) using touch only (i.e., by feeling the objects, one hand at a time, with eyes closed)
- Spinal cord: ends at L1. Nerve roots hence take an increasingly long course to reach their respective exit foramina. Spinal cord levels relative to vertebral bodies are:
- Upper cervical: same level
- Lower cervical: one level higher
- Upper thoracic: two levels higher
- Lower thoracic: two to three levels higher
- Lumbar: T10 – T12
- Sacral: T12 – L1
- Dermatomes
- C4: regimental patch
- C5: lateral aspect of arm
- C6: thumb, lateral aspect of forearm
- C7: middle finger
- C8: little finger
- T1: medial aspect of arm
- L1: anterior aspect of inguinal ligament
- L2: mid-thigh, especially lateral aspect
- L3: just proximal to the knee, anterior aspect
- L4: medial calf
- L5: lateral calf, dorsal aspect of proximal foot
- S1: plantar aspect of foot, dorsal aspect of toes
- S2: posterior aspect of thigh, in the midline
- Peripheral nerve distribution
- Axillary nerve: lateral aspect of arm, over deltoid
- Median cutaneous nerve: median aspect of arm
- Lateral cutaneous nerve of forearm: lateral aspect of forearm
- Median cutaneous nerve of forearm: median aspect of forearm
- Median nerve: lateral three-and-a-half digits, palmar aspect
- Ulnar nerve: median one-and-a-half digits, palmar aspect
- Radial nerve: anatomical snuffbox / first dorsal web space
- Lateral femoral cutaneous nerve: lateral aspect of thigh
- Anterior femoral cutaneous nerve: anterior aspect of thigh (midline)
- Obturator nerve: medial aspect of upper thigh
- Posterior femoral cutaneous nerve: posterior aspect of thigh
- Lateral sural cutaneous nerve: lateral aspect of leg
- Saphenous nerve: medial aspect of leg
- Superficial peroneal nerve: dorsal aspect of medial foot, except first web space
- Deep peroneal nerve: first dorsal web space of foot
- Sural nerve: dorsal aspect of 5th toe, posterior aspect of leg (midline)