What cervical nerve roots supply the scapula?

Cervical Nerve Roots Supplying the Scapula

The scapula is primarily innervated by cervical nerve roots C5 and C6, with variable contributions from C4, C7, and C8 depending on the specific scapular muscle. 1, 2

Specific Nerve Supply to Scapular Muscles

Suprascapular Nerve

• Originates from the upper trunk of the brachial plexus (C5-C6, occasionally C4)
• Supplies the supraspinatus and infraspinatus muscles 2, 3
• C5 is consistently the largest contributor of nerve fibers to this nerve 3
• Studies show C5 and C6 innervation in 76% of cases, C4-C5-C6 in 18%, and C5 alone in 6% 3

Subscapular Nerves

• Superior subscapular nerve:

  • Innervates the upper and middle (thoracic) portions of the subscapularis muscle
  • Derived from C5 and C6 nerve roots 2

• Lower subscapular nerve:

  • Innervates the lower (axillary) portion of the subscapularis and teres major muscles
  • Composed of C5-C6-C7 roots in 76.9% of cases and C6-C7 roots in 23.1% of cases 4
  • Often shares fascicular pathways with the axillary nerve 4

Axillary Nerve

• Supplies the teres minor muscle and deltoid (which overlies the scapula)
• Primarily derived from C5 and C6 nerve roots, with occasional C7 contribution 2

Thoracodorsal Nerve

• Supplies the latissimus dorsi muscle (which attaches to the scapula)
• Derived from C6, C7, and C8 nerve roots 2

Segmental Innervation Pattern

The segmental innervation of scapular muscles follows this pattern:

• C5 (and occasionally C6): Supraspinatus muscle 2, 3
• C5 and C6: Infraspinatus, thoracic portion of subscapularis, and teres minor 2
• C5, C6, (and occasionally C7): Deltoid 2
• C5, C6, and C7: Axillary portion of subscapularis and teres major 2, 4
• C6, C7, and C8: Latissimus dorsi 2

Clinical Significance

• Injuries to the upper trunk of the brachial plexus (C5-C6) significantly impact scapular function, particularly affecting shoulder abduction and external rotation 5
• In brachial plexus reconstruction, transfer of the accessory nerve to the suprascapular nerve can help restore shoulder function, especially when combined with other nerve transfers 5
• The suprascapular nerve has a unique characteristic of receiving fibers from both anterior and posterior divisions of the brachial plexus 6
• Understanding the segmental innervation is crucial for accurate diagnosis and management of cervical radiculopathies affecting scapular function 1

Diagnostic Considerations

• MRI of the brachial plexus is the preferred imaging modality for evaluating suspected plexopathies affecting scapular function 1
• Electrodiagnostic studies help confirm clinical diagnosis of plexopathy affecting scapular muscles 1
• When evaluating scapular weakness, it's important to differentiate between preganglionic (nerve root) and postganglionic (plexus) injuries as treatment approaches differ 1