occipital

Occipital is an anatomical term derived from Latin occiput, meaning the back of the head. In medical usage it describes structures related to the posterior portion of the skull or to the posterior part of the cerebral cortex known as the occipital lobe. The term can apply to bones, regions, nerves, and vessels associated with this area.

Occipital bone: The occipital bone forms the posterior skull and contributes to the posterior cranial fossa. It surrounds the foramen magnum, through which the brainstem and first spinal cord segments pass. Its main parts are the squamous part at the back, the basilar part at the skull base, and the two occipital condyles that articulate with the atlas. External features include the external occipital protuberance and the superior and inferior nuchal lines; internally there are grooves for the transverse and sigmoid sinuses and the internal occipital crest.

Occipital lobe: In the cerebrum, the occipital lobe sits at the posterior cerebral cortex and is primarily involved in visual processing. The primary visual cortex lies along the calcarine fissure, with surrounding areas analyzing color, motion, and form.

Clinical relevance: Damage to the occipital lobe can cause visual field defects and visual agnosia. Trauma to the occipital region of the skull may indicate basilar skull injury. The greater occipital nerve supplies sensation to the posterior scalp and can be a source of occipital neuralgia and headaches. The occipital arteries and veins vascularize the posterior scalp.

Development and variation: The occipital bone ossifies from several centers in early life, with sutures allowing growth; variations in size and shape occur but are typically benign.