C1 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: Path of the Hypoglossal nerve¹

Figure 2: Nerve roots extending from the spinal cord¹

Anatoy

C1 lacks a dorsal root²

Innervation

This root supplies muscles that provide multiple functions:

• Support the head
• Fix the neck
• Assist in neck flexion
• Assist in extension
• Tilt the head to one side

Specific Muscle innervations

infrahyoid muscles.

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

Lesion

Due to the lack of motor root, C1 lesions are characterized purely by motor symptoms².

Clinically, C1 lesions usually result in minor motor difficulties.

“Because there is no dorsal root from C1, lesions of this root result in purely motor symptoms. This root supplies muscles that support the head, fix the neck, assist in neck flexion and extension, and tilt the head to one side. These, include the longus capitis, rectus capitis, obliquus capitis, longissimus capitis and cervicis, multifidi, intertransversarii, rotatores, semispinalis, and infrahyoid muscles. C1 lesions usually result in minor motor difficulties.”²

Case Study

Greathouse DG, Joshi A. Radiculopathy of the eighth cervical nerve. J Orthop Sports Phys Ther. 2010;40(12):811-817. doi:10.2519/jospt.2010.3187

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.