C4 Nerve Root (C4)

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: Hypoglossal nerve, cervical plexus, and their respective branches¹

Figure 2: Nerve roots extending from the spinal cord¹

Motor Innervation

Muscle	Origin	Insertion	Innervation	Action
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
Infraspinatus	Infraspinous Fossa of Scapula	Greater tubercle of Humerus	Suprascapular n. C4 - C6	GHJ: ER, Stabilization
Levator scapulae	C1-C4 TP	Superior angle of Scapula	Dorsal scapular n. Cervical spinal nn. C3 - C4	Scapula: Elevation, Downward rotation Cervical: I/L sidebend
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
Lower trapezius	T5-T12 SP	Scapular spine	Accessory n. (CN XI) C3 - C4	Scapula: Retraction, Depression, Upward rotation, Stabilizes scapula on thorax
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
Middle trapezius	Aponeurosis of T1-T4 SP	Acromion	Accessory n. (CN XI) C3 - C4	Scapula: Retraction
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
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
Sternocleidomastoid	Manubrium Medial third of Clavicle	Mastoid process Superior nuchal line	CN XI Accessory n. Cervical plexus C1 - C4	Unilateral: I/L cervical sidebend, C/L cervical rotation Bilateral: Head extension, Cervical Flexion, Assists in respiration, Prevents posterior translation during mastication SCJ stabilization
Supraspinatus	Supraspinous Fossa of scapula	Greater tubercle of Humerus	Suprascapular n. C4 - C6	GHJ: Initiates abduction, Stabilization
Upper trapezius	Occiput SP C1-C7	lateral 1/3 of Clavicle	Accessory n. (CN XI) C3 - C4	Scapula: Elevation, Upward rotatino Neck: I/L sidebend, C/L Rotation

Dermatome

Figure 3: Dermatomal cutaneous distribution¹

Figure 4: Dermatomal cutaneous distribution (Posterior)¹

Lesion

“Sensory signs and symptoms occur on the lower neck. Paresis occurs in the scalene and levator scapulae muscles (lateral neck flexion and scapular rotation, respectively), rhomboid muscles (scapular elevation and adduction), trapezius muscle (shoulder elevation), and some muscles of the neck. Diaphragmatic paresis may also occur because some fibers reach the phrenic nerve. There is no reflex impairment.”²

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.