Thoracic and Lumbar
MYOTOMES, DERMATOMES AND REFLEXES OF THE LOWER EXTREMITY
Dermatomes
source:web.uni-plovdiv.bg
L1: Lateral Hip
L2: Lateral to inner thigh
L3: Lateral hip to medial knee
L4: Lateral mid hip, over anterior knee, to big toe
L5: Lateral lower leg to middle 3 toes
S1: Lateral foot and lateral malleolus
S2: Bottom of the heel to posterior calf/thigh
L1 & L2: Hip flexion
L3: Knee extension
L4: Dorsiflexion & eversion
L5: Great toe extension & inversion
S1: Plantar flexion & knee flexion
S2: Great toe flexion
Source: www.glowm.com
Myotomes
When testing the dermatomes, you are assessing sensation. Have the subject close their eyes while you use a sharp (pinwheel, pen cap, etc.) and dull object (scissors handle, pencil eraser, etc.). Brush the skin with the object and ask them to decipher between sharp and dull. If they are having issues with discrepancies between limbs, have the subject close their eyes and run an object (fingernails, pens, pen caps, etc.) down the specific dermatome on both limbs. Ask them to describe any differences and where it occured.
When assessing the myotomes, compare bilaterally. Have the subject do both motions at the same time, and feel for strength differences, as well as any trembling that could indicate a neurological condition.
LOWER LEVEL REFLEXES
PATELLAR REFLEX:
This reflex is affected by L2, L3 and L4.
To test this reflex, have the patient sit hook seated in a relaxed state. Locate the patellar tendon, and strike it with a reflex hammer. Look for the leg to kick out slightly. If there is no movement, then try striking the tendon again.
Some patients may have issues staying relaxed, causing the reflex to not fire. A trick to help distract them is to have them clasp their hands together and tell them to focus on pulling them apart as hard as they can. If there is still no movement, then there could be damage to that nerve root.
Another sign to look for is an exaggerated reflex in which the leg kicks out excessively. This could also be the patient being unable to stay relaxed, or could indicate a nerve pathology. If damage is suspected, refer them to a specialist.
MEDIAL HAMSTRING REFLEX:
This reflex is affected by L5.
To test this reflex, have the patient lie prone and totally relaxed. Find the medial hamstring by having the patient resist knee flexion. Once found, place two fingers over the tendon, then strike your fingers with the reflex hammer. Look for a contraction of the hamstrings. If no contraction is seen, then readjust fingers and strike again.
The same rules apply as above with patients being unable to relax causing exaggerrated or dimished results.
ACHILLES TENDON REFLEX:
This reflex is affected by S1 and S2.
To test this reflex, have the patient sit hook seated, in a relaxed state. Put your hand under their foot and slightly dorsi flex until they are in a neutral position. Locate the achilles tendon, then strike it with the reflex hammer. Look and feel for the gastroc to contract and the foot to plantar flex into your hand.
Same as stated above, patients may be unable to relax, affecting results.