Splenius Capitis Muscle, Lateral View

Description

Running obliquely from the spinous processes of the upper thoracic vertebrae toward the mastoid region, the splenius capitis forms a broad posterior triangle of muscle on the lateral neck. It lies deep and posterior to the sternocleidomastoideus, with its superior fibers approaching the mastoid process of the temporal bone and the lateral third of the superior nuchal line of the occipital bone. Anteriorly, the mandible and the contours of the temporal region sit superficial to the deeper lateral skull base, while the upper cervical vertebrae provide the posterior midline attachment points for the overlying cervical musculature. Facial muscles such as orbicularis oculi and the cheek and perioral musculature frame the lateral profile. Clinically, this lateral relationship between sternocleidomastoideus and splenius capitis matters when differentiating anterior neck pain and torticollis patterns from posterior cervical strain. Palpation and trigger point referral from splenius capitis often produces occipital and retro-orbital headache patterns, and it can mimic cervicogenic headache when cervical facet irritation coexists. The fiber direction also clarifies its action: unilateral contraction contributes to ipsilateral rotation and lateral flexion, while bilateral activation extends the head and upper cervical spine. A key landmark. Use this artwork in head and neck anatomy teaching blocks, chiropractic and physiotherapy materials on posterior cervical myofascial pain, and surgical or procedural education that needs clean surface and deep muscle layering around the mastoid and upper cervical region (for example, planning safe injection planes in cervicogenic headache management). Anatomical accuracy verified by SciePro's Medical Advisory Board.