External occipital crest

External Occipital Crest

The external occipital crest is a prominent ridge located on the external surface of the occipital bone, which is situated at the back of the skull. It serves as an important anatomical landmark and plays a crucial role in providing attachment sites for various muscles and ligaments.

Anatomy

The external occipital crest is a midline ridge that extends vertically from the external occipital protuberance to the foramen magnum. It is a bony prominence that can be palpated on the posterior aspect of the skull. The crest is formed by the convergence of the nuchal lines, which are horizontal ridges that run laterally from the external occipital protuberance.

Function

The primary function of the external occipital crest is to provide attachment points for several muscles and ligaments involved in head and neck movement. Some of the important structures that attach to this crest include:

• Ligamentum nuchae: This elastic ligament extends from the external occipital protuberance to the spinous processes of the cervical vertebrae. It helps to support the weight of the head and maintain an upright posture.

• Occipitalis muscle: This muscle is part of the occipitofrontalis muscle, which covers the top of the skull. It originates from the superior nuchal line and inserts into the galea aponeurotica, a broad tendon that covers the frontal bone.

• Trapezius muscle: The trapezius muscle is a large muscle that extends from the occipital bone to the thoracic vertebrae and the clavicle. It helps to move and stabilize the scapula and the shoulder joint.

• Semispinalis capitis muscle: This muscle is located deep in the back of the neck and extends from the cervical and thoracic vertebrae to the occipital bone. It helps to extend and rotate the head.

Clinical Significance

The external occipital crest is an important landmark for various medical procedures and surgical interventions. It can be used as a reference point for determining the midline of the skull during surgeries involving the posterior cranial fossa. Additionally, abnormalities or variations in the size or shape of the crest may be indicative of certain congenital or acquired conditions.

See Also

• Occipital bone
• Foramen magnum
• Nuchal lines
• Ligamentum nuchae
• Occipitofrontalis muscle
• Trapezius muscle
• Semispinalis capitis muscle