Occipital Horns | Brain Parts

Occipital Horns aka Posterior Horns

Author

Definition

The occipital horns are part of the ventricular system and more specifically the posterior extension of the lateral ventricles that lie within the occipital lobes and surrounded by white matter.

Structrally they are chatracterized by their position as they extend laterally from the body of the ventricles and then curve gently medially and transition to the atria. Anteriorly they are relatively broad but as they curve posteriorly they thin and their shape is truly “horn- like”

The vectors of the ventricular System Overlaid on the Brain

The ventricular system is overlaid on a drawing of the brain. Each limb of the horizontal component is situated in a cerebral hemisphere. The angled parts that extend inferiorly represent the temporal horns. The vertical limb includes the third and fourth ventricles

Sagittal View of the Ventricles – Basics

Recesses

The diagram in the sagittal projection reveals the horizontal portion called the lateral ventricle. It is a paired structure that houses the frontal horn, body, and the vertical portion which is composed of the 3rd ventricle, cerebral aqueduct and the 4th ventricle. The lateral ventricle consists of the frontal horn, body, occipital horn, atrium and the temporal horn The foramen of Monro connects the lateral ventricles with the third ventricle. The paired foramina of Luschka are sitiuated anteriorly in the 4th ventricle and they allow CSF to circulate in the subarachnoid spaces. The foramen of Magendie is a single structure and is situated posteriorly and it also enables CSF to enter the subarachnoid space. code brain ventricles lateral ventricles frontal horn body occipital horn atrium temporal horn 3rd ventricle 4th ventricle foramen of Monro formamen of Magendie Foramen of Luschka anatomy normal neuroanatomy diagram conceptual diagram structure principles Davidoff Art Courtesy Ashley Davidoff MD copyright 2010 all rights

Asymmetry of the Occipital Horns – Normal Variant

The MRI shows a FLAIR and a T2 weighted image revealing normal asymmetric development of the lateral ventricles in a 41 year old female.

Applied Biology – Diseases

Encephalomalacia, Ex Vacuo Change and Asymmetric Enlargement of the Posterior Horn

The CT scan of this 94 year old patient reveals asymmetry in the occipital horns caused by volume loss of the posterior right parietal lobe as a result of a chronic right middle cerebral infarction. The posterior horn of the ventricle has expanded to fill the space left by the encephalomalacia as a result of the infarction. This is called ex vacuo change and results in asymmetric enlargement of the ipsilateral ventricle.

Acute Hemorrhagic Stroke of the BAsal Ganglia

Dependant Blood in the Occiptal Horns

The CT is from a 33year old male with an acute left basal ganglial hemorrhagic stroke. The CT shows a hyperdense accumulation of hemorrhage(d) complicated by extension or rupture of the hemorrhage into the ipsilateral choroid plexus (green arrows a,b,c) and hemorrhage into the ventricles with blood lying dependently in the occipital horns (maroon arrows in c) and midline shift with septum pellucidum (white arrow of the eyes (lenses overlaid in d) mass effect on the left frontal horn (d) and midline shift exemplified by the shift of the septum pellucidum (white arrow c).