Quick Facts
Origin: Superior articular processes of C4-C7 vertebrae; transverse processes of T1-T6 vertebrae.
Insertion: Area located between superior and inferior nuchal lines of occipital bone.
Action: Extends and rotates the head.
Innervation: Greater occipital (C2) and third cervical nerves.
Arterial Supply: Occipital, deep cervical, and vertebral arteries, dorsal branches of upper posterior intercostal arteries.
Related parts of the anatomy
Origin
The semispinalis capitis muscle originates from the:
- superior articular processes of the fourth to seventh cervical vertebrae;
- transverse processes of the first to sixth thoracic vertebrae.
There can be variations between individuals regarding the origin sites for the semispinalis muscles (Tubbs, Shoja and Loukas, 2016).
Insertion
The fibers of the semispinalis capitis muscle travel superiorly along the upper back and posterior neck regions and insert onto the area of the occipital bone that is located between the superior and inferior nuchal lines. There can be variations between individuals regarding the insertion sites for the semispinalis muscles (Tubbs, Shoja and Loukas, 2016).
Key Features & Anatomical Relations
Overall, the semispinalis muscles are the more superficial of the three muscles of the transversospinal muscles. They are intrinsic muscles of the back and are found along the upper back and posterior neck regions. They are long, flat skeletal muscles that are composed of three parts:
- semispinalis capitis, which is the superior portion;
- semispinalis colli, which is the middle portion;
- semispinalis thoracis, which is the large, inferior portion.
The semispinalis muscles are located:
- superficial to the suboccipital and multifidus muscles;
- deep to the trapezius, splenius capitis, splenius colli, and erector spinae muscles;
- medial to the levatores costarum breves and longi muscles;
- lateral to the interspinales muscles.
Actions
The semispinalis capitis muscle is involved in multiple actions:
- during unilateral contraction, it rotates the head to the opposite side at the atlantoaxial joints;
- during bilateral contraction, it extends the head at the atlantooccipital joints (Netter, 2011).
List of Clinical Correlates
- Occipital neuralgia
References
Netter, F. H. (2011) Atlas of Human Anatomy. Netter Basic Science Series: Saunders/Elsevier.
Tubbs, R. S., Shoja, M. M. and Loukas, M. (2016) Bergman's Comprehensive Encyclopedia of Human Anatomic Variation. Wiley.
