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The occipitalis muscle (occipital belly) is a muscle which covers parts of the skull. Some sources consider the occipital muscle to be a distinct muscle. However, Terminologia Anatomica currently classifies it as part of the occipitofrontalis muscle along with the frontalis muscle. The occipitalis muscle is thin and quadrilateral in form.
To it is attached, the splenius capitis muscle, the trapezius muscle, [1] and the occipitalis. [2] From the external occipital protuberance a ridge or crest, the external occipital crest also called the median nuchal line, often faintly marked, descends to the foramen magnum, and affords attachment to the nuchal ligament.
The nuchal ligament and trapezius muscle attach to it. The inion (ἰνίον, iníon, Greek for the occipital bone) is used as a landmark in the 10-20 system in electroencephalography (EEG) recording. Extending laterally from it on either side is the superior nuchal line, and above it is the faintly marked highest nuchal line.
The epicranial muscle (also called the epicranius) has two sections: the occipital belly, near the occipital bone, and the frontal belly, near the frontal bone. It is supplied by the supraorbital artery, the supratrochlear artery, and the occipital artery. It is innervated by the facial nerve.
In humans, the epicranial aponeurosis originates from the external occipital protuberance and highest nuchal lines of the occipital bone. [1] It merges with the occipitofrontalis muscle. In front, it forms a short and narrow prolongation between its union with the frontalis muscle (the frontal part of the occipitofrontalis muscle).
The foramina in the base of the skull are exit and entry points for veins, arteries and cranial nerves. The cranial nerves as they exit through various foramina.
The calvaria is made up of the superior portions of the frontal bone, occipital bone, and parietal bones. [1] In the human skull, the sutures between the bones normally remain flexible during the first few years of postnatal development, and fontanelles are palpable. Premature complete ossification of these sutures is called craniosynostosis.
The nuchal ligament extends from the external occipital protuberance on the skull and median nuchal line to the spinous process of the seventh cervical vertebra in the lower part of the neck. [ 1 ] From the anterior border of the nuchal ligament, a fibrous lamina is given off.