D5.4_O2.6 Dermatomes and Myotomes_NR.pptx

DERMATOMES & MYOTOMES Objectives: Understand what a dermatome and myotome is and how they are derived. Understand the difference between spinal levels and peripheral nerves. H E AT H E R G A R V I N , P H D , D - A B FA  Embryo Somites  Dermatomes,...

DERMATOMES & MYOTOMES Objectives: Understand what a dermatome and myotome is and how they are derived. Understand the difference between spinal levels and peripheral nerves. H E AT H E R G A R V I N , P H D , D - A B FA  Embryo Somites  Dermatomes, Myotomes, (& Sclerotomes) @ each vertebral level Myotomomes splite: Epimere (Mid-Back = Dorsal Rami), Hypomere (all else = Ventral Rami) Dorsal & Ventral Rami Dermatomes & MyotomesMyotomes- Certain spinal levels responsible for certain actions (muscles masses by Dermatomes-strip of skin spinal nn) innervated by single spinal - Can test for weakness to level determine spinal nerve issue -can test sensation to determine spinal nerve issue  Lower Limb Myotomes Testing Myotomes: Common Tests L3/L4 – Patellar Ligament Reflex (Quadriceps); knee extension Would expect weak L5 – Extensor digitorum longus reflex ; toe knee extension on extension injured side S1 – Calcaneal (Achilles) Tendon Reflex; (compared to other plantarflexion side). Flexion Extensi on Dermatomes  Testing Dermatomes Lower Limb Dermatomes L1 – Prox Med thigh @ groin (iliac crest) L2- Ant mid- thigh L3 – Medial Knee (Med fem condyle) L4 – Medial Malleolus L5 – Dorsum Medial Foot (1st web) S1 – Lateral Malleolus, Toes 4 & 5 S2 – Popliteal Fossa (medial) This S3 –isIschial just an example; you do not need Tuberosity to memorize the lower limb dermatomes at this moment! Spinal Levels vs Peripheral Nerves Peripheral nerves are NAMED nerves (e.g., Sciatic nerve), which are many times made up of MULTIPLE spinal levels. The brachial plexus is a good example of this. Questions? [email protected]