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Myotomes: Difference between revisions

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|+ Complete Myotome Chart
|+ Complete Myotome Chart
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! Muscle !! Nerve !!Spinal Roots
! Muscle !! Nerve !! colspan="7" |Spinal Roots
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!colspan="3" style="text-align: center;" class="tableSubHeading"|Upper Limb <ref>{{#pmid:26409623}}</ref><ref name="brain"></ref>
! colspan="9" style="text-align: center;" class="tableSubHeading" |Upper Limb <ref>{{#pmid:26409623}}</ref><ref name="brain"></ref>
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|Trapezius|| Spinal accessory nerve ||C3, C4
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!C3
!C4
!C5
!C6
!C7
!C8
!T1
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|Supraspinatus, infraspinatus || rowspan="6"|Brachial plexus||'''C5''', C6
|Trapezius|| Spinal accessory nerve ||🔲
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|Pectoralis major || C5, C6, C7, C8
|Supraspinatus, infraspinatus ||Suprascapular nerve||
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|Latissimus dorsi || C6, '''C7''', C8
|Pectoralis major
|Lateral and medial pectoral nerves||
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|Teres major, serratus anterior || C5, C6, C7
|Latissimus dorsi
|Thoracodorsal nerve||
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|Serratus anterior || C5, C6, C7
|Teres major
|Lower subscapular nerve||
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|Rhomboids||C4, C5
|Serratus anterior
|Long thoracic nerve||
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|Deltoid || Axillary nerve ||C5, C6
|Rhomboids
|Dorsal scapular nerve||
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|Biceps and brachialis || Musculocutaneous nerve || C5, C6
|Deltoid || Axillary nerve ||
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|Triceps || rowspan="3"|Radial nerve || C6, '''C7''', C8
|Biceps and brachialis || Musculocutaneous nerve ||
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|Brachioradialis|| C5, '''C6'''
|Triceps || rowspan="3" |Radial nerve ||
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|Wrist extensors (radial) || '''C6''', C7
|Brachioradialis||  
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|FCR, pronator teres || rowspan="2"|Median nerve|| C6, C7
|Wrist extensors (radial) ||  
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|FDS, Thenar || C8, '''T1'''
|FCR, pronator teres || rowspan="2" |Median nerve||
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|FPL, FDP, PQ || Anterior interosseous nerve|| C7, '''C8''', T1
|FDS, Thenar ||
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|EDC, EPL || Posterior interosseous nerve|| '''C7''', C8, T1
|FPL, FDP, PQ || Anterior interosseous nerve||  
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|FCU || rowspan="4"|Ulnar nerve|| C7, '''C8''', T1
|EDC, EPL || Posterior interosseous nerve||
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|FDP radial digits || '''C8''', T1
|FCU || rowspan="4" |Ulnar nerve||
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|FDP ulnar digits || C7, '''C8''', T1
|FDP radial digits ||  
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|Interossei || C7, C8, '''T1'''
|FDP ulnar digits ||  
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!colspan="3"  style="text-align: center;" class="tableSubHeading"|Lower Limb <ref name="brain"></ref>
|Interossei ||
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|Iliopsoas ||rowspan="2"|Femoral nerve|| '''L1''', '''L2''', L3
! colspan="9" style="text-align: center;" class="tableSubHeading" |Lower Limb <ref name="brain"></ref>
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|Quadriceps femoris || L2, '''L3''', '''L4'''
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!L1
!L2
!L3
!L4
!L5
!S1
!S2
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|Adductor longus and magnus ||Obturator nerve|| '''L2''', '''L3''', L4
|Iliopsoas || rowspan="2" |Femoral nerve|| 🟦
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|Gluteus medius, minimis, tensor fascia lata||Superior gluteal nerve ||'''L4''', '''L5''', S1
|Quadriceps femoris ||  
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|Gluteus maximus||Inferior gluteal nerve||'''L5''', '''S1''', S2
|Adductor longus and magnus ||Obturator nerve||  
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|Semitendinosus, biceps femoris, semimembranosus|| rowspan="5"|Sciatic and tibial nerves||L5, '''S1''', S2
|Gluteus medius, minimis, tensor fascia lata||Superior gluteal nerve ||
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|Gastrocnemius and soleus||S1, S2
|Gluteus maximus||Inferior gluteal nerve||
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|Tibialis posterior||L4, L5
|Semitendinosus, biceps femoris, semimembranosus|| rowspan="5" |Sciatic and tibial nerves||
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|Flexor digitorum longus||L5, '''S1''', '''S2'''
|Gastrocnemius and soleus||
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|Abductor hallucis, abductor digiti minimi, interossei || S1, S2
|Tibialis posterior||
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|Tibialis anterior|| rowspan="3"|Sciatic and common peroneal nerves||'''L4''', L5
|Flexor digitorum longus||
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|Extensor digitorum longus, extensor hallucis longus||'''L5''', S1
|Abductor hallucis, abductor digiti minimi, interossei ||
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|Extensor digitorum brevis, peroneus longus, peroneus brevis||L5, S1
|Tibialis anterior|| rowspan="3" |Sciatic and common peroneal nerves||
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|Extensor digitorum longus, extensor hallucis longus||
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|Extensor digitorum brevis, peroneus longus, peroneus brevis||
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Revision as of 20:09, 12 September 2021

This article is still missing information.

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.

Simplified Examination

Simplified myotomes[1]
Spinal Level Movement
Upper Limb
C5 Shoulder abduction
C6 Elbow flexion
C7 Elbow extension
C8 Finger flexion
T1 Finger abduction
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 lesions[2]
Movement UMN Root Reflex Nerve Muscle
Upper Limb
Shoulder abduction ++ C5 Axillary Deltoid
Elbow flexion C5/6
C6		 +
+		 Musculocutaneous
Radial		 Biceps
Brachioradialis
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 nerve
Ulnar		 Flexor pollicis longus and flexor digitorum profundus (index)
Flexor digitorum profundus (ring and little)
Finger abduction ++
 		 T1
T1		 Ulnar
Median		 First dorsal interosseous
Abductor pollicis brevis
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
Upper Limb [3][2]
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 🔲 🟦
Wrist extensors (radial) 🟦 🔲
FCR, pronator teres Median nerve 🔲 🔲
FDS, Thenar 🔲 🟦
FPL, FDP, PQ Anterior interosseous nerve 🔲 🟦 🔲
EDC, EPL Posterior interosseous nerve 🟦 🔲 🔲
FCU Ulnar nerve 🔲 🟦 🔲
FDP radial digits 🟦 🔲
FDP ulnar digits 🔲 🟦 🔲
Interossei 🔲 🔲 🟦
Lower Limb [2]
L1 L2 L3 L4 L5 S1 S2
Iliopsoas Femoral nerve 🟦 🟦 🔲
Quadriceps femoris 🔲 🟦 🟦
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 and tibial nerves 🔲 🟦 🔲
Gastrocnemius and soleus 🔲 🔲
Tibialis posterior 🔲 🔲
Flexor digitorum longus 🔲 🟦 🟦
Abductor hallucis, abductor digiti minimi, interossei 🔲 🔲
Tibialis anterior Sciatic and common peroneal nerves 🟦 🔲
Extensor digitorum longus, extensor hallucis longus 🟦 🔲
Extensor digitorum brevis, peroneus longus, peroneus brevis 🔲 🔲

Myotome Dance

Myotome Dance
Spinal Levels Memory Aid Action
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
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


References

  1. ↑ The Noted Anatomist. Myotomes. Feb 29, 2020. Available on youtube
  2. ↑ 2.0 2.1 2.2 Brain. Aids to the Examination of the Peripheral Nervous System, 4th edition. 2000
  3. ↑ Bell et al.. Refinement of myotome values in the upper limb: Evidence from brachial plexus injuries. The surgeon : journal of the Royal Colleges of Surgeons of Edinburgh and Ireland 2017. 15:1-6. PMID: 26409623. DOI.
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