C5 Nerve Root

Authors
Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Nerve roots extending from the spinal cord

Contribution

C5 and C6 contribute to the Superior trunk of the brachial plexus.

Motor Innervation

Warning: No 'path' link found for variable 'ref-anterior-deltoid' in YAML data.
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Muscle Origin Insertion Innervation Action
Anterior deltoid Lateral third of clavicle Deltoid tuberosity of humerus Axillary n.
C5 - C6		 GHJ: Flexion, IR, Adduction
Anterior scalene Anterior tubercle of TP of C3-C6 Scalene tubercle of 1st Rib Anterior Rami
C4 - C6		 Mobile ribs: Elevates ribs during forced inspiration
Fixed ribs (unilateral): I/L C/s sidebend (unilateral)
Fixed ribs (bil): C/s flexion, Cervical lateral stabilization
Biceps brachii Long head Supraglenoid tubercle of scapula
Adjacent rim of Glenoid Labrum		 Radial tuberosity
Bicipital aponeurosis		 Musculocutaneous n.
C5 - C6		 Elbow: Flexion, Supination
GHJ: Flexion, Stabilization of humeral head during deltoid contraction, Abduction, IR
Biceps brachii Short head Coracoid process Radial tuberosity
Bicipital aponeurosis		 Musculocutaneous n.
C5 - C6		 Elbow: Flexion, Supination
GHJ: Flexion, Stabilization of humeral head during deltoid contraction, Abduction, IR
Brachialis Distal half of anterior Humerus Ulnar tuberosity Musculocutaneous n.
Radial n.
C5 - C7		 Elbow: Flexion
Brachioradialis Lateral distal humerus
Lateral intermuscular septum		 Styloid process of Radius Radial n.
C5 - C6		 Elbow: Flexion, Semipronation (to 90°)
Coracobrachialis Coracoid process Humerus (in line with crest of lesser tubercle) Musculocutaneous n.
C5 - C7		 GHJ: Flexion, Adduction, IR
Infraspinatus Infraspinous Fossa of Scapula Greater tubercle of Humerus Suprascapular n.
C4 - C6		 GHJ: ER, Stabilization
Lateral deltoid Acromion Deltoid tuberosity of humerus Axillary n.
C5 - C6		 GHJ: Abduction
Longissimus capitis T1-T3 TP
C4-C7 TP & articular process		 Mastoid process Spinal nn.
Posterior rami (lateral br.)
C1 - C5		 Bilateral: Head extension
Unilateral: Ipsilateral head sidebend, Ipsilateral rotation
Longissimus cervicis T1-T6 TP C2-C5 TP Spinal nn. Posterior rami (lateral br.)
C1 - C5		 Bilateral: Extends spine
Unilateral: Ipsilateral spine sidebend
Longissimus thoracis Sacrum
Iliac crest
Lumbar vertebrae SP
Lower thoracic TP		 2-12 Ribs
Thoracic TP
Lumbar TP		 Spinal nn. Posterior rami (lateral br.)
C1 - C5		 Bilateral: Extends spine
Unilateral: Ipsilateral spine sidebend
Middle scalene C1-C2 TP
Posterior tubercle of TP of C3-C7		 1st Rib (posterior to groove for subclavian a.) Anterior Rami
C3 - C8		 Mobile ribs: Elevates ribs during forced inspiration
Fixed ribs (unilateral): I/L C/s sidebend (unilateral)
Fixed ribs (bil): C/s flexion, Cervical lateral stabilization
Pectoralis major Clavicle (medial half)
Sternum
Costal cartilages 1-6
Rectus sheath (anterior layer)		 Humerus (crest of greater tubercle) Lateral pectoral n.
Medial pectoral n.
C5 - T1		 Entire muscle: Adduction, IR
Clavicular & Sternocostal parts: Flexion, Aids in respiration when shoulder is fixed
Posterior deltoid Scapular spine Deltoid tuberosity of humerus Axillary n.
C5 - C6		 GHJ: Extension, ER, Abduction
Rhomboid major T1-T4 SP Medial border of scapula (below scapular spine) Dorsal scapular n.
C4 - C5		 Scapula: Retraction, Downward rotation, Stabilization
Rhomboid minor C6 & C7 SP Medial border of scapula (above scapular spine) Dorsal scapular n.
C4 - C5		 Scapula: Retraction, Downward rotation, Stabilization
Serratus anterior 1-9 Ribs Superior angle of Scapula (costal and dorsal surfaces)
Medial border of scapula (costal surface)
Medial border of scapula (costal surface)
Inferior angle of Scapula (costal & dorsal surfaces)		 Long thoracic n.
C5 - C7		 Superior part: Lowers raised arm
Entire mm.: Protraction, Rib elevation (with fixed shoulder)
Inferior part: Rotates scapula laterally forward
Splenius capitis Nuchal lig.
C7-T4 SP		 Lateral third of nuchal line
Mastoid process		 Spinal nn.
Posterior rami (lateral br.)
C1 - C6		 Bilateral: Head and neck extension
Unilateral: I/L sidebend, I/L rotation
Splenius cervicis T3-T7 SP C1-C4 SP Spinal nn.
Posterior rami (lateral br.)
C1 - C6		 Bilateral: Head and neck extension
Unilateral: I/L sidebend, I/L rotation
Subclavius 1st rib Clavicle (inferior surface) N. to subclavius
C5 - C6		 SCJ: Stabilization
Subscapularis Subscapular fossa Lesser tubercle of Humerus Upper Subscapular n.
Lower Subscapular n.
C5 - C6		 GHJ: IR, Stabilization
Supraspinatus Supraspinous Fossa of scapula Greater tubercle of Humerus Suprascapular n.
C4 - C6		 GHJ: Initiates abduction, Stabilization
Teres major Inferior angle of Scapula Crest of lesser tubercle of humerus Thoracodorsal n.
C5 - C6		 GHJ: IR, Adduction, Extension
Teres minor Greater tubercle of Humerus Axillary n.
C5 - C6		 GHJ: ER, Weak adduction

Dermatome

Figure 2: Dermatomal cutaneous distribution
Figure 3: Dermatomal cutaneous distribution (Posterior)

Lesion

“C5 nerve root involvement results in neck, shoulder, and upper anterior arm pain. Sensory disturbances occur on the lateral arm with these lesions. Paresis occurs predominantly and variably in the following muscles: levator scapulae, rhomboids, serratus anterior, supraspinatus, infraspinatus, deltoid, biceps, and brachioradialis (for methods of examination of each of these muscles, see Chapter 2 ). Diaphragmatic paresis may rarely occur owing to C5 fibers reaching the phrenic nerve. The biceps reflex (subserved by segments C5 C6) and the brachioradialis reflex (C5 C6) may be depressed.”

DDX

Level

C4/C5

Sensation

Deltoid and lateral arm

Motor

  • Deltoid
  • Biceps

Abnormal DTR

Bicep reflex

References

1.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
2.
Brazis PW, Masdeu JC, Biller J. Localization in Clinical Neurology. 8th ed. Wolters Kluwer Health; 2022.
3.
Hong CG, Nam WD. Reliability and Diagnostic Accuracy of Standard Dermatomes and Myotomes for Determining the Pathologic Level in Surgically Verified Patients With Cervical Radiculopathy. Neurospine. 2022;19(4):1006-1012. doi:10.14245/ns.2244194.097

Citation

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