basilar

Basilar is an adjective meaning related to the base or foundation of something. In anatomy it is used to describe several structures located at or near the base of the skull or along the ventral surface of the brainstem, and in broader medical usage it can denote base-related features of other organs.

The basilar artery is a major vessel of the posterior circulation of the brain. It is formed by the fusion of the two vertebral arteries and runs along the ventral surface of the brainstem. Along its course it gives off several branches, including the anterior inferior cerebellar arteries (AICA) and the superior cerebellar arteries (SCA), and it ultimately divides into the posterior cerebral arteries (PCA). The basilar artery supplies the brainstem, cerebellum, and portions of the thalamus and occipital lobes. Occlusion or thrombosis of the basilar artery is a serious condition that can cause brainstem stroke and life-threatening neurological deficits.

The basilar membrane is a critical structure within the cochlea of the inner ear. It extends along the length of the cochlear duct and forms the boundary between the scala tympani and the scala media. Its stiffness and width vary from base to apex, enabling frequency discrimination as part of the organ of Corti. Sounds induce vibrations of the basilar membrane, which stimulate hair cells and convert mechanical energy into neural signals. In general, higher frequencies peak basally and lower frequencies peak apically.

The term basilar skull refers to the base of the skull, formed by several bones including the occipital, sphenoid, temporal, and ethmoid bones. Basilar skull fractures result from significant trauma and can involve leakage of cerebrospinal fluid, cranial nerve injury, or intracranial complications. Signs may include raccoon eyes or Battle’s sign, and prompt evaluation is important.

Etymology: basilar derives from Latin basilaris, meaning pertaining to the base.