The obliquus capitis inferior is a small, deep muscle located at the base of the skull in the upper neck. It is part of the suboccipital muscle group, located beneath the occipital bone at the back of the head. This muscle plays a role in head movement and can sometimes be a source of discomfort.
Anatomy of the Obliquus Capitis Inferior
This muscle has specific attachments that define its role in neck movement. It originates from the spinous process of the second cervical vertebra, often called the axis or C2. From there, the muscle extends upwards and laterally to insert onto the transverse process of the first cervical vertebra, known as the atlas or C1.
The obliquus capitis inferior is unique among the suboccipital muscles because it is the only one that does not attach directly to the skull. It also forms the lower boundary of the suboccipital triangle, an anatomical region containing important nerves and blood vessels.
The Function of the Obliquus Capitis Inferior
The primary function of the obliquus capitis inferior is to rotate the head to the same side (ipsilateral rotation) at the atlantoaxial joint. For example, turning your head to the right engages the right obliquus capitis inferior.
Beyond rotation, this muscle also contributes to head extension, which is when you tilt your head backward. It works with other suboccipital muscles to stabilize the atlantoaxial joint, helping to maintain the head’s position during various body movements.
Common Causes of Pain and Tension
The obliquus capitis inferior muscle can become a source of pain and tension due to various factors. Prolonged poor posture, particularly forward head posture from extended computer or smartphone use, can strain these muscles. This sustained forward position, often called “text neck,” causes the neck extensors to work harder, leading to tightness and discomfort.
Whiplash injuries, involving a sudden forceful back-and-forth movement of the neck, can also cause strain and pain in this muscle. Sleeping in an awkward position or clenching the jaw due to stress are additional common culprits that can lead to muscle tightness. Tension in the obliquus capitis inferior and other suboccipital muscles frequently contributes to cervicogenic headaches, which originate from the neck and are often felt at the base of the skull or behind the eyes.
Relief and Stretches
Relieving tension in the obliquus capitis inferior often involves gentle stretching and improving posture. One effective exercise is the chin tuck, which helps lengthen the muscles at the back of the neck. To perform this, sit or stand tall, keeping your head level, and gently draw your chin straight back as if trying to make a double chin. You should feel a gentle stretch at the base of your skull.
After performing a chin tuck, you can add a gentle rotation. While maintaining the chin-tucked position, slowly turn your head to one side, feeling the stretch along the opposite side of your neck. Hold each stretch for 20-30 seconds, breathing deeply, and repeat on both sides. Perform these stretches gently and stop immediately if you experience sharp pain. Always consult with a doctor or physical therapist before attempting new exercises, especially if you have a pre-existing neck condition or injury.