C2 Nerve Root (C2)

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: Path of the Hypoglossal nerve¹

Figure 3: Nerve roots extending from the spinal cord¹

Motor Innervation

Muscle	Origin	Insertion	Innervation	Action
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
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

Dermatome

Figure 4: Dermatomal cutaneous distribution¹

Figure 5: Dermatomal cutaneous distribution (Posterior)¹

Lesion

“Sensory symptoms and signs due to C2 lesions are localized to the scalp posterior to the interaural line (the C2 dermatome). The motor supply of this segment involves the same muscles responsible for head and neck movements as those innervated by segment C1. In addition, the C2 nerve helps supply the sternocleidomastoid muscle (head rotation and flexion)

which is predominantly innervated by the spinal accessory nerve (cranial nerve XI).”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.