Semispinalis Capitis: Origin, Insertion, Nerve & Tension Headaches

The Semispinalis Capitis is a massive, thick muscle located in the upper back and neck. It is the largest muscle of the posterior neck and is the primary extensor of the head. It acts as a "roof" over the suboccipital triangle and is notoriously involved in chronic tension headaches.

[Image of Longissimus Capitis anatomy]

Quick Anatomy Snapshot

Group	Transversospinalis (Deep Back Muscles).
Origin (Proximal)	Transverse processes of T1-T6 (Upper Thoracic) and Articular processes of C4-C7.
Insertion (Distal)	Between the Superior and Inferior Nuchal Lines of the Occipital Bone.
Nerve Supply	Greater Occipital Nerve and branches of posterior rami of cervical spinal nerves.
Primary Actions	Bilateral: Powerful extension of the head. Unilateral: Mild Contralateral Rotation (turns head to opposite side).

Deep Dive: The Headache Trigger

The Semispinalis Capitis sits deep to the Splenius and Trapezius but superficial to the suboccipital muscles.

1. The "Pierced" Muscle

This muscle has a critical relationship with the Greater Occipital Nerve (C2). This nerve pierces directly through the muscle belly of the Semispinalis Capitis to reach the scalp. Consequently, if the muscle is tight or in spasm, it strangles the nerve, causing "Occipital Neuralgia"—a headache that shoots up the back of the skull to the eye.

2. The Anti-Gravity Role

Due to the weight of the head being anterior to the spine, the head naturally wants to drop forward (flex). The Semispinalis Capitis is the primary "anti-gravity" muscle that maintains an upright head position throughout the day. This constant workload makes it highly prone to fatigue and trigger points.

Physio Corner: Clinical Relevance

💪 Functional Fact: In "Forward Head Posture" (Text Neck), the Semispinalis Capitis is locked in a shortened, tense state to stop the head from falling further forward. This chronic isometric contraction is the root cause of many tension headaches.

Palpation

Have the patient lie prone. Locate the spinous processes of the cervical spine. Move laterally about 1 inch into the thick paravertebral muscle mass. The Semispinalis Capitis feels like two thick, vertical "pythons" running up the back of the neck to the skull. It is best felt when the patient extends their head slightly against resistance.

⚠️ Clinical Pathology: Occipital Neuralgia
Entrapment of the Greater Occipital Nerve within the Semispinalis Capitis causes piercing, electric-shock-like pain in the upper neck, back of the head, and behind the ears. Treatment often involves releasing this specific muscle.

Manual Muscle Testing (MMT)

We test Capital Extension (Head on Neck).

Testing Tip: Ensure the motion occurs at the skull base (chin lift), not just the lower neck.

Step-by-Step Procedure (Oxford Scale)

Grade	Patient Action & Resistance
Grade 3, 4, 5 (Against Gravity)	Position: Prone (face down), head hanging off the edge of the table. Action: Patient extends the head (looks up at the wall), lifting the chin. Resistance: Applied to the Occiput (back of head), pushing down. Grade 3: Full range against gravity. Grade 4/5: Holds against moderate/strong resistance.
Grade 0, 1 (Palpation)	Action: Palpate the thick muscle belly lateral to the midline just below the skull base. Cue: "Try to look up." Grade 1: Strong contraction felt. Grade 0: No activity.

Frequently Asked Questions

Does it rotate the head?

Yes, but weakly. It assists in Contralateral Rotation (turning the head to the opposite side), unlike the Splenius Capitis which rotates to the same side.

Is it part of the Erector Spinae?

No. It belongs to the Transversospinalis group (along with Multifidus and Rotatores), which lies deeper than the Erector Spinae.

What muscles cover it?

The Splenius Capitis and the Trapezius cover the Semispinalis Capitis.

Test Your Knowledge: Semispinalis Capitis Quiz

1. Which nerve pierces the Semispinalis Capitis?

2. What is the primary action of this muscle?

3. Which group does Semispinalis belong to?

4. Where does the Semispinalis Capitis insert?

5. Which muscle lies superficial to Semispinalis Capitis?

6. Where does the Semispinalis Capitis originate?

7. The unilateral rotation of this muscle is:

8. This muscle is the roof of which anatomical triangle?

9. Chronic tension in Semispinalis Capitis is strongly linked to:

10. True or False: Semispinalis Capitis is the largest muscle in the posterior neck.

References

• Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2018). Clinically Oriented Anatomy. 8th ed. Philadelphia: Wolters Kluwer.
• Standring, S. (2016). Gray's Anatomy: The Anatomical Basis of Clinical Practice. 41st ed. Elsevier.
• Travell, J. G., & Simons, D. G. (1999). Myofascial Pain and Dysfunction: The Trigger Point Manual. 2nd ed. Williams & Wilkins.