Myotomes

A myotome is the group of muscles that a single spinal nerve innervates. Most muscles are innervated by more than one spinal nerve root, and therefore consist of multiple myotomes. Understanding the myotomes is integral for performing an accurate motor system examination. 
==Simplified Examination==
 Simplified myotomesThe Noted Anatomist. Myotomes. Feb 29, 2020. Available on youtube 
Spinal Level	Movement
Upper Limb 	Upper Limb
C5 	Shoulder abduction
C6 	Elbow flexion
C7 	Elbow extension
C8 	Finger flexion
T1 	Finger abduction
Lower Limb 	Lower Limb
L2 	Hip flexion
L3 	Hip adduction
L4 	Knee extension
L5 	Ankle dorsiflexion
S1 	Ankle plantarflexion
==Commonly Tested Movements==
 Commonly tested movements. UMN column are movements that are preferentially weak in UMN lesionsBrain. Aids to the Examination of the Peripheral Nervous System, 4th edition. 2000
Movement 	UMN 	Root 	Reflex 	Nerve 	Muscle
Upper Limb 	Upper Limb	Upper Limb	Upper Limb	Upper Limb 	Upper Limb
Shoulder abduction 	++ 	C5 	 	Axillary 	Deltoid
Elbow flexion 	 	C5/6C6 	++ 	MusculocutaneousRadial 	BicepsBrachioradialis
Elbow extension 	+ 	C7 	+ 	Radial 	Triceps
Radial wrist extension	+ 	C6 	 	Radial 	Extensor carpi radialis longus
Finger extension 	+ 	C7 	 	Posterior interosseous nerve 	Extensor digitorum communis
Finger flexion 	 	C8  	+  	Anterior interosseous nerveUlnar	Flexor pollicis longus and flexor digitorum profundus (index)Flexor digitorum profundus (ring and little)
Finger abduction 	++  	T1T1 	 	UlnarMedian 	First dorsal interosseousAbductor pollicis brevis
Lower Limb 	Lower Limb	Lower Limb	Lower Limb	Lower Limb 	Lower Limb
Hip flexion 	++ 	L1/2 	 	 	Iliopsoas
Hip adduction 	 	L2/3 	+ 	Obturator 	Adductors
Hip extension 	 	L5/S1 	 	Sciatic 	Gluteus Maximus
Knee flexion 	+ 	S1 	 	Sciatic 	Hamstrings
Knee extension 	 	L3/4 	+ 	Femoral 	Quadriceps
Ankle dorsiflexion 	++ 	L4 	 	Deep peroneal 	Tibialis anterior
Ankle eversion 	 	L5/S1 	 	Superficial peroneal 	Peronei
Ankle plantarflexion 	 	S1/S2 	+ 	Tibial 	Gastrocnemius, soleus
Big toe extension 	 	L5 	 	Deep peroneal 	Extensor hallucis longus
==Complete Myotome Chart==
 Complete Myotome Chart
Muscle 	Nerve 	Spinal Roots 	Spinal Roots 	Spinal Roots 	Spinal Roots 	Spinal Roots 	Spinal Roots 	Spinal Roots
Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.	Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.	Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.	Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.	Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.	Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.	Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.	Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.	Upper Limb McGee, Steven R. Evidence-based physical diagnosis. Philadelphia, PA: Elsevier, 2018.
 	 	C3 	C4 	C5 	C6 	C7 	C8 	T1
Trapezius 	Spinal accessory nerve 	🔲 	🔲 	 	 	 	 	
Supraspinatus, infraspinatus 	Suprascapular nerve 	 	 	🔳 	🔲 	 	 	
Pectoralis major 	Lateral and medial pectoral nerves 	 	 	🔲 	🔲 	🔲 	🔲 	
Latissimus dorsi 	Thoracodorsal nerve 	 	 	 	🔲 	🔳 	🔲 	
Teres major 	Lower subscapular nerve 	 	 	🔲 	🔲 	🔲 	 	
Serratus anterior 	Long thoracic nerve 	 	 	🔲 	🔲 	🔲 	 	
Rhomboids 	Dorsal scapular nerve 	 	🔲 	🔲 	 	 	 	
Deltoid 	Axillary nerve 	 	 	🔲 	🔲 	 	 	
Biceps and brachialis 	Musculocutaneous nerve 	 	 	🔲 	🔲 	 	 	
Triceps 	Radial nerve 	 	 	 	🔲 	🔳 	🔲 	
Brachioradialis 	Radial nerve 	 	 	🔲 	🔳 	 	 	
ECRL 	Radial nerve 	 	 	🔲 	🔳 	🔲 	 	
ECU 	Radial nerve 	 	 	 	 	🔳 	🔲 	
Finger extensors 	Radial nerve 	 	 	 	 	🔲 	🔲 	
FCR, pronator teres 	Median nerve 	 	 	 	🔲 	🔲 	 	
FDS 	Median nerve 	 	 	 	 	 	🔲 	🔳
APB 	Median nerve 	 	 	 	 	 	🔲 	🔲
FPL, FDP, PQ 	Anterior interosseous nerve 	 	 	 	 	🔲 	🔳 	🔲
EDC, EPL 	Posterior interosseous nerve 	 	 	 	 	🔳 	🔲 	🔲
FCU 	Ulnar nerve 	 	 	 	 	🔲 	🔳 	🔲
FDP radial digits 	Ulnar nerve 	 	 	 	 	 	🔳 	🔲
FDP ulnar digits 	Ulnar nerve 	 	 	 	 	🔲 	🔳 	🔲
Interossei 	Ulnar nerve 	 	 	 	 	🔲 	🔲 	🔳
Lower Limb 	Lower Limb 	Lower Limb 	Lower Limb 	Lower Limb 	Lower Limb 	Lower Limb 	Lower Limb 	Lower Limb
 	 	L1 	L2 	L3 	L4 	L5 	S1 	S2
Iliopsoas 	Femoral nerve 	🔳 	🔳 	🔲 	 	 	 	
Quadriceps femoris 	Femoral nerve 	 	🔲 	🔳 	🔳 	 	 	
Adductor longus and magnus 	Obturator nerve 	 	🔳 	🔳 	🔲 	 	 	
Gluteus medius, minimis, tensor fascia lata 	Superior gluteal nerve 	 	 	 	🔳 	🔳 	🔲 	
Gluteus maximus 	Inferior gluteal nerve 	 	 	 	 	🔳 	🔳 	🔲
Semitendinosus, biceps femoris, semimembranosus 	Sciatic nerve trunk† 	 	 	 	 	🔲 	🔳 	🔲
Tibialis posterior 	Tibial nerve† 	 	 	 	🔲 	🔲 	 	
Gastrocnemius and soleus 	Tibial nerve† 	 	 	 	 	 	🔲 	🔲
Flexor digitorum longus 	Tibial nerve† 	 	 	 	 	🔲 	🔳 	🔳
Tibialis anterior 	Peroneal nerve† 	 	 	 	🔳 	🔲 	 	
Extensor digitorum longus, extensor hallucis longus 	Peroneal nerve† 	 	 	 	 	🔳 	🔲 	
Abductor hallucis, abductor digiti minimi, interossei 	Peroneal nerve† 	 	 	 	 	 	🔲 	🔲
Extensor digitorum brevis, peroneus longus, peroneus brevis 	Peroneal nerve† 	 	 	 	 	🔲 	🔲 	
🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.	🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.	🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.	🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.	🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.	🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.	🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.	🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.	🔲 segmental contribution, 🔳 significant segmental contribution.
† The sciatic nerve trunk divides above the knee into the peroneal and tibial nerves, therefore lesions of the sciatic nerve trunk affect the muscles of all three branches.
==Myotome Dance==
<youtube>9oiEofZCJQo</youtube>
 Myotome Dance
Spinal Levels	Memory Aid 	Action
Upper Limb 	Upper Limb 	Upper Limb
C1, 2 	I nod to you 	Neck flexion/extension
C3 	Don’t tickle me 	Neck lateral flexion
C4 	I’m not sure 	Shoulder elevation
C5 	Feel alive 	Shoulder flexion, abduction, & lateral rotation
C6, 7, 8 	Close the gate 	Shoulder extension, adduction & medial rotation
C5, 6 	Pick up sticks 	Elbow flexion
C7, 8 	Lay them straight 	Elbow extension
C5, 6 	Flick my wrists 	Forearm supination
C7, 8 	The time is late 	Forearm pronation
C6, 7 	Fly up to heaven 	Wrist flexion & extension
C7 	Paper 	Finger extension
C8 	Rock 	Finger flexion (though some sources say C7, 8 does both finger extension and flexion)
T1 	Scissors 	Finger abduction & adduction
Lower Limb 	Lower Limb 	Lower Limb
L2, 3 	Lift my knee 	Hip flexion
L3, 4 	Kick the door 	Knee extension (& knee-jerk reaction)
L4, 5 	Foot points to the sky 	Ankle dorsiflexion
L4, 5 	Extend my thigh 	Hip extension
L5, S1, (S2) 	Kick my bum (Run to poo) 	Knee flexion
S1, 2 	Stand on my shoes 	Ankle plantarflexion (& ankle jerk)
L2, 3, 4 	Modestly close the door 	Hip adduction & internal/medial rotation
L4 - S2 	The opposite is true 	Hip abduction & external/lateral rotation
C3, 4, 5 	Keeps the diaphragm alive	Innervates the diaphragm
S2, 3, 4 	Keeps poo off the floor 	Innervates bowel, bladder, sex organs, anal sphincter, pelvic muscles. (& anal wink reflex)
Note
*T1-12 Supplies chest wall and abdominal muscles
*L1 Contributes to hip flexion & adduction
*L5, S1, S2 Babinski plantar reflex/extensor response in UMN lesion
==Other Videos==
<youtube>I5ehobv9A3Q</youtube>
==References==
Category:Examination
Category:Partially complete articles
Category:Spine Anatomy