Dermatomes and Myotomal Maps

Author: Michelle Lin, MD
Updated: 5/26/2013

Dermatomes and Myotomal Maps

Dermatome map diagram

Testing Motor Function by Level

| Nerve Level | Motor Function | | --- | --- | | C1-C4 | Spontaneous breathing | | C5 | Shoulder abduction (deltoid) | | C6 | Wrist extension (carpi radialis longus and brevis) | | C7 | Elbow extension (triceps) | | C8 | Finger flexion (flexor digitorum superficialis/profundis, lumbricals) | | T1 | Finger adduction & abduction (dorsal/palmar interossei, abductor digiti quinti) | | T1-T12 | Intercostal and abdominal muscles | | T12-L3 | Hip flexion (iliopsoas) | | L2-L4 | Hip flexion, knee extension (quadriceps), hip adduction | L4 | Ankle dorsiflexion and inversion (anterior tibialis) | | L5 | Big toe extension (ext hallucis longus), heel walk (ext digitorum), hip abduction (gluteus medius) | | S1 | Ankle plantarflexion and eversion (peroneus longus), toe walk (peroneus brevis), hip extension (gluteus maximus) | | S2-S4 | Rectal sphincter tone |

References

  1. "Dermatomes Anatomy: Overview, Gross Anatomy, Natural Variants". Emedicine.medscape.com. N.p., 2017. Web. 24 Mar. 2017. [Source]