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Myotomes
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Commonly Tested Movements
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
Muscle | Nerve | Spinal Roots |
---|---|---|
Upper Limb [2][1] | ||
Trapezius | Spinal accessory nerve | C3, C4 |
Supraspinatus | Brachial plexus | C5, C6 |
Infraspinatus | C5, C6 | |
Pectoralis major | C5, C6, C7, C8 | |
Latissimus dorsi | C6, C7, C8 | |
Teres major | C5, C6, C7 | |
Deltoid | Axillary nerve | C5, C6 |
Biceps and brachialis | Musculocutaneous nerve | C5, C6 |
Triceps | Radial nerve | C6, C7, C8 |
Brachioradialis | C5, C6 | |
Wrist extensors (radial) | C6, C7 | |
EDC | C7, C8, T1 | |
EPL | C7, C8, T1 | |
FCR | C6, C7 | |
FCU | C7, C8, T1 | |
FDP radial digits | C8, T1 | |
FDP ulnar digits | C7, C8, T1 | |
FDS | C8, T1 | |
FPL | C7, C8, T1 | |
Thenar | C8, T1 | |
Interossei | C7, C8, T1 | |
Lower Limb [1] | ||
Iliopsoas | Femoral nerve | L1, L2, L3 |
Quadriceps femoris | L2, L3, L4 | |
Adductor longus and magnus | Obturator nerve | L2, L3, L4 |
Gluteus medius, minimis, tensor fascia lata | Superior gluteal nerve | L4, L5, S1 |
Gluteus maximus | Inferior gluteal nerve | L5, S1, S2 |
Semitendinosus, biceps femoris, semimembranosus | Sciatic and tibial nerves | L5, S1, S2 |
Gastrocnemius and soleus | S1, S2 | |
Tibialis posterior | L4, L5 | |
Flexor digitorum longus | L5, S1, S2 | |
Abductor hallucis, abductor digiti minimi, interossei | S1, S2 | |
Tibialis anterior | Sciatic and common peroneal nerves | L4, L5 |
Extensor digitorum longus, extensor hallucis longus | L5, S1 | |
Extensor digitorum brevis, peroneus longus, peroneus brevis | L5, S1 |
Myotome Dance
- C1, 2 โ I nod to you โ Neck flexion/extension
- C3 โ Donโt tickle me โ Neck lateral flexion
- C4 โ Iโm not sure โ Shoulder elevation
- C5 โ Feel alive โ Shoulder flexion, abduction, & lateral rotation
- C6, 7, 8 โ Close the gate โ Shoulder extension, adduction & medial rotation
- C5, 6 โ Pick up sticks โ Elbow flexion
- C7, 8 โ Lay them straight โ Elbow extension
- C5, 6 โ Flick my wrists โ Forearm supination
- C7, 8 โ The time is late โ Forearm pronation
- C6, 7 โ Fly up to heaven โ Wrist flexion & extension
- C7 โ Paper โ Finger extension
- C8 โ Rock โ Finger flexion (though some sources say C7, 8 does both finger extension and flexion)
- T1 โ Scissors โ Finger abduction & adduction
- (T1-12 โ Supplies chest wall and abdominal muscles)
- (L1 โ Contributes to hip flexion & adduction)
Kicking a ball:
- L2, 3 โ Lift my knee โ Hip flexion
- L3, 4 โ Kick the door โ Knee extension (& knee-jerk reaction)
- L4, 5 โ Foot points to the sky โ Ankle dorsiflexion
Bringing foot back to the floor:
- L4, 5 โ Extend my thigh โ Hip extension
- L5, S1, (S2) โ Kick my bum (Run to poo) โ Knee flexion
- S1, 2 โ Stand on my shoes โ Ankle plantarflexion (& ankle jerk)
- (Babinski plantar reflex/extensor response in UMN lesion is L5, S1, S2)
- L2, 3, 4 โ Modestly close the door โ Hip adduction & internal/medial rotation
- L4 - S2 โ The opposite is true โ Hip abduction & external/lateral rotation
- C3, 4, 5 - Keeps the diaphragm alive โ Innervates the diaphragm
- S2, 3, 4 โ Keeps poo off the floor โ Innervates bowel, bladder, sex organs, anal sphincter, pelvic muscles. (& anal wink reflex)
References
- โ 1.0 1.1 1.2 Brain. Aids to the Examination of the Peripheral Nervous System, 4th edition. 2000
- โ 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.