Myotomes Of The Upper Limb

Upper limb myotomes refer to muscles innervated by cervical (C1-C8) and first thoracic (T1) spinal nerve roots. Key functions include: C1-C2 for neck flexion; C3 for neck side flexion; C4 for shoulder elevation; C5 for shoulder abduction; C6 for elbow flexion/wrist extension; C7 for elbow extension/wrist flexion; C8 for thumb extension; and T1 for hand intrinsic muscle movements. These myotomes are used clinically to assess nerve root function and localize neurological injuries.

Myotomes of the Upper Limb include the muscles that is innervated by the cervical spine roots C1 to C1 including the first thoracic root T1.

Cervical Myotomes

Neck flexion: C1–C2
Neck side flexion: C3 and cranial nerve XI
Shoulder elevation: C4 and cranial nerve XI
Shoulder abduction/shoulder lateral rotation: C5
Elbow flexion and/or wrist extension: C6
Elbow extension and/or wrist flexion: C7
Thumb extension and/or ulnar deviation: C8
Abduction and/or adduction of hand intrinsics: T1

See Also: Cervical Spine Range of Motion

Detailed Myotomes of the Upper Limb

Nerve Root	Action	Muscles
C1-C2	Neck flexion	Rectus lateralis, rectus capitis anterior, longus capitis, longus coli, longus cervicis, sternocleidomastoid
C3	Neck side flexion	Longus capitis, longus cervicis, trapezius, scalenus medius
C4	Shoulder elevation	Diaphragm, trapezius, levator scapulae, scalenus anterior, scalenus medius
C5	Shoulder abduction	Rhomboid major and minor, deltoid, supraspinatus, infraspinatus, teres minor, biceps, scalenus anterior and medius
C6	Elbow flexion and wrist extension	Serratus anterior, latissimus dorsi, subscapularis, teres major, pectoralis major (clavicular head), biceps, coracobrachialis, brachialis, brachioradialis, supinator, extensor carpi radialis longus, scalenus anterior, medius and posterior
C7	Elbow extension and wrist flexion	Serratus anterior, latissimus dorsi, pectoralis major (sternal head), pectoralis minor, triceps, pronator teres, flexor carpi radialis, flexor digitorum superficialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, scalenus medius and posterior
C8	Thumb extension and ulnar deviation	Pectoralis major (sternal head), pectoralis minor, triceps, flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus, pronator quadratus, flexor carpi ulnaris, abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis, extensor indicis, abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, scalenus medius and posterior
T1	Hand intrinsics	Flexor digitorum profundus, intrinsic muscles of the hand (except extensor pollicis brevis), flexor pollicis brevis, opponens pollicis

Muscles listed may be supplied by additional nerve roots; only primary nerve root sources are listed

See Also: Dermatome Distribution

Upper Limb Myotomes — Myotomes of the Upper Limb

References & More

Orthopedic Physical Assessment by David J. Magee, 7th Edition.
Javed O, Maldonado KA, Ashmyan R. Anatomy, Shoulder and Upper Limb, Muscles. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482410/
Bell SW, Brown MJ, Hems TJ. Refinement of myotome values in the upper limb: Evidence from brachial plexus injuries. Surgeon. 2017 Feb;15(1):1-6. doi: 10.1016/j.surge.2015.08.004. Epub 2015 Sep 26. PMID: 26409623. Pubmed