Dermatomes and Myotomes Dermatomes are areas on the surface of the skin that are control by specific nerve roots from the spinal cord Myotomes correspond to muscles that are controlled by specific nerve roots from the spinal cord Cranial Nerves branch out off the brain (12) Nerve Roots branch out off the spinal cord (31) info.med.yale.edu/ caim/cnerves/ www.informeddecision.com/options/ lowback/dclmlama.htm These nerve roots branch out to form a plexus which is a network of intersecting nerves which travel to different parts of the body, they are both motor and sensory Cervical Plexus1 C1-C4 nerve roots innervate the diaphragm, shoulder and neck. Brachial Plexus2 C5-T1 nerve roots innervate the upper limbs Lumbosacral Plexus3 L1- L5, S2 nerve roots innervate the lower extremity 1. http://instruct.westvalley.edu/granieri/cervical%20plexus.jpg 2. www.medical-look.com/.../Brachial_Plexus.jpg 3. "LifeART (and/or) MediClip image copyright (2005) Lippincott Williams & Wilkins. All rights reserv Skin (sensation) is innervated by a single nerve roots called the dermatomes Muscles (movement) are innervated by singe nerve roots called myotomes Nerves and nerve roots are typically injured by compression or stretching forces When a nerve root is damaged a deficit may occur in the corresponding limb The evaluation of nerve root damage can be done by testing dermatomes and myotomes Nerve root trauma should always be inspected by a physician Dermatomes Test for abnormalities in sensitivity by using a pinwheel, paper clip or finger nail The athlete should close his/her eyes and give the therapist feedback with regards to various stimuli All tests should be compared bilaterally Nerve Root Dermatome Patterns Upper Extremity C1 C2 C3 C4 C5 C6 C7 C8 T1 Top of head Temporal & occipital regions of head Neck and posterior cheek Superior shoulder and clavicle Deltoid patch & lateral arm Lateral forearm, thumb and index finger Posterior lateral forearm & middle finger Medial forearm, ulna border & ring/little fingers Medial side of forearm & upper arm Lower Extremity L1 L2 L3 L4 L5 S1 S2 Back, hip and groin Anterior superior thigh, medial thigh above knee Back, anterior thigh and medial knee Lateral thigh/knee, anterior medial lower leg to medial aspect of big toe Lateral knee and lateral lower leg and top of foot Buttocks, posterior lateral thigh and lateral plantar surface of foot Buttocks, posterior medial thigh and medial plantar surface of foot Figure 24-4 Dermatome distribution of the spinal nerves.From Thibodeau GA, Patton KT: Anatomy and Physiology,ed 6, St. Louis, 2006, Mosby. (Cameron, Michelle H.. Physical Rehabilitation: Evidence-Based Examination, Evaluation, and Intervention. W.B. Saunders Company, 032007.). <vbk:978-0-7216-0361-2#B9780721603612500272_f4> Myotomes Test with resistive exercises The clinician will check for weakness in strength All tests should be compared bilaterally Upper Extremity Nerve Root C4 C5 C6 C7 C8 T1 Muscle Upper traps Deltoids, Biceps Biceps, Wrist Ext Wrist Flexors, Elbow Ext Thumb Ext, Flexors Hand Intrinsics Test tested with resisted shoulder shrugs/elevation tested with resisted shoulder abduction tested with resisted elbow flexion, wrist extension tested with resisted wrist flexion, elbow extension tested with resisted thumb extension fingers abduction & adduction Lower Extremity Nerve Routes L1-L2 L3 L4 L5 S1/S2 Muscle Test Iliopsoas, hip adductors tested with resisted hip flexion Quadriceps tested with resisted knee extension Anterior Tibialis, tested with resisted foot dorsiflexion Extensor Hallucis, Glut Medius tested with resisted great toe extension Gastrocnenius tested with plantar flexion