Splenius Capitis: Origin, Insertion, Nerve, Action & The "Bandage" Muscle

The Splenius Capitis is a broad, strap-like muscle in the back of the neck. Its name is derived from the Greek word splenion, meaning "bandage," because it looks like a bandage wrapped around the deeper neck muscles. It acts as a primary mover for head extension and rotation.

[Image of Longissimus Capitis anatomy]

Quick Anatomy Snapshot

Layer	Superficial layer of intrinsic back muscles (Spinotransversales).
Origin (Proximal)	Lower half of the Nuchal Ligament and Spinous Processes of C7 to T3 (or T4).
Insertion (Distal)	Mastoid Process (Temporal bone) and the lateral third of the Superior Nuchal Line (Occipital bone).
Nerve Supply	Lateral branches of the Posterior Rami of middle cervical spinal nerves (C3-C4).
Primary Actions	Bilateral: Extension of the head and neck. Unilateral: Lateral flexion and Rotation of the head to the same side (Ipsilateral).

Deep Dive: The Anatomical "V"

The Splenius Capitis works in conjunction with the Splenius Cervicis. Together, the two Splenius Capitis muscles (left and right) form a "V" shape on the back of the neck.

1. The Muscular Sandwich

The Splenius Capitis is located in the "middle" of the neck layers:
• Deep to: Trapezius and Sternocleidomastoid (SCM).
• Superficial to: Semispinalis Capitis and Longissimus Capitis.
It holds the deep extensors in place, acting literally like a bandage.

2. The Rotation Mechanism

Unlike the Trapezius or SCM (which rotate the head to the opposite side), the Splenius Capitis pulls the mastoid process posteriorly and medially. This turns the face toward the same side as the contracting muscle.

Physio Corner: Clinical Relevance

💪 Functional Fact: The Splenius Capitis is your "Blind Spot" muscle. When driving, checking your blind spot requires extension, lateral flexion, and rotation to the same side—the exact combined action of this muscle.

Palpation

1. Locate the upper fibers of the Trapezius and the Sternocleidomastoid (SCM).
2. Find the triangular space between them (the floor of the posterior triangle).
3. The Splenius Capitis forms the floor of this triangle.
4. Ask the patient to rotate their head toward you against resistance. You will feel the muscle strap tighten just inferior to the mastoid process.

⚠️ Clinical Pathology: Tension Headaches
Trigger points in the Splenius Capitis are a major cause of vertex headaches. The pain is typically referred to the top of the head (vertex) or sometimes behind the eye, mimicking a migraine. This is common in people with "Forward Head Posture" (Text Neck).

Manual Muscle Testing (MMT)

We test the combined action of extension and rotation.

Testing Tip: To differentiate from the Trapezius (which extends), add the rotation component. To differentiate from the SCM (which rotates), add the extension component.

Step-by-Step Procedure (Oxford Scale)

Grade	Patient Action & Resistance
Grade 3, 4, 5 (Against Gravity)	Position: Prone (face down), head off the table. Action: Patient looks up (extension) and turns the head to the Right (to test the Right muscle). Resistance: Applied to the posterolateral occiput (right side), pushing down and to the left (into flexion and opposite rotation). Grade 3: Holds position against gravity. Grade 4/5: Holds against resistance.
Grade 0, 1 (Palpation)	Action: Palpate the muscular floor between the upper Trapezius and SCM. Cue: "Try to turn your head and look up." Grade 1: Contraction felt. Grade 0: No activity.

Frequently Asked Questions

How is it different from Splenius Cervicis?

Capitis: Inserts on the Skull (Mastoid/Occiput). Moves the head.
Cervicis: Inserts on the Transverse Processes of C1-C3. Moves the neck. It is located inferior and lateral to the Capitis.

Is it superficial or deep?

It is considered a Superficial Intrinsic back muscle. It is deep to the Trapezius (extrinsic), but superficial to the Erector Spinae and Semispinalis (deep intrinsic).

Does it help with posture?

Yes. Bilateral contraction prevents the head from dropping forward (resists flexion). In forward head posture, these muscles are "locked long" (eccentrically loaded) and often become painful.

Test Your Knowledge: Splenius Capitis Quiz

1. What does "Splenius" mean?

2. Where does the Splenius Capitis insert?

3. What is the unilateral action of this muscle?

4. Which muscle covers the lower portion of the Splenius Capitis?

5. Where does the Splenius Capitis originate?

6. Which nerve supplies the Splenius Capitis?

7. The Splenius Capitis forms the floor of which anatomical triangle?

8. Trigger points in this muscle refer pain to the:

9. Which muscle lies immediately deep to the Splenius Capitis?

10. True or False: Splenius Capitis helps with forced inspiration.

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.