Declive

At a glance

English

Declive

Latin (TA2)

Declive

System

Brain and spinal cord

Region

Head

Side

Single, on the midline

About the declive

The declive is a subdivision of the vermis, the narrow midline strip that joins the two cerebellar hemispheres. Its name means a slope: on the upper surface of the cerebellum the vermis rises to a peak at the culmen and then falls away towards the back, and the declive forms this downward slope. In the numbered scheme of Larsell it is vermal lobule VI.

Its front boundary is the primary fissure, the deep cleft that divides the anterior lobe of the cerebellum from the posterior lobe, so the declive is the first vermal lobule of the posterior lobe. Behind, the posterior superior fissure separates it from the folium of the vermis. On each side it is continuous with the simple lobule of the hemisphere, the part sometimes called the posterior quadrangular lobule, and together these form a band of cortex just behind the primary fissure.

Like the rest of the cerebellar cortex it has three layers, molecular, Purkinje cell and granular, folded into thin parallel folia. Purkinje cells of the vermis send their output mainly to the fastigial nucleus, which connects with the vestibular nuclei and the reticular formation of the brainstem. The vermis as a whole is concerned with posture, balance and the movements of the trunk and the eyes, and the region formed by lobules VI and VII of the vermis is known as the oculomotor vermis because it helps to keep saccadic eye movements accurate.

Damage to the vermis tends to cause unsteadiness of stance and gait rather than clumsiness of the limbs. Lesions involving the oculomotor vermis can make saccades overshoot or undershoot their target.

Function and supply

Function

Part of the posterior lobe vermis: helps control posture and balance and, with the folium and tuber, keeps rapid eye movements accurate.

Blood supply

Superior vermian branches of the superior cerebellar artery.