Anterior horn
May refer also to Anterior grey column.
The term anterior horn (also frontal horn, anterior cornu, frontal cornu) may refer to either of two separate anatomical structures within the central nervous system:
anterior horn of lateral ventricle in the brain, which passes forward, laterally, and slightly downward from the interventricular foramen into the frontal lobe anterior horn of spinal cord, the ventral (front) grey matter section of the spinal cord which contains motor neurons that affect the skeletal muscles.
The anterior horn of the lateral ventricle (also anterior cornu of the lateral ventricle, frontal horn of the lateral ventricle or precornu) is a portion of the lateral ventricle that passes forward and laterally, with a slight inclination downward, from the interventricular foramen into the frontal lobe, curving around the anterior end of the caudate nucleus. Its floor is formed by the upper surface of the reflected portion of the corpus callosum, the rostrum. It is bounded medially by the anterior portion of the septum pellucidum, and laterally by the head of the caudate nucleus. Its apex reaches the posterior surface of the genu of the corpus callosum.
The frontal horn is located at the depth of approximately 18 mm (range, 17-20 mm) from the orbital surface of the frontal brain. In a lateral perspective, the tip of the frontal horn is in line with the tip of the temporal pole. Wide opening of the Sylvian fissure, relaxation of the brain and lateral basal frontal exposure can be used effectively to obtain a suitable angulation for conduct of surgery. Avoidance of olfactory tracts and Heubner's perforating artery at the site of medial orbital gyrus cortical incision and appropriately directing the corticectomy that avoids the association fibre tracts, caudate head and internal capsule can lead to a safe exposure of the frontal horn. The approach is suitable for lesions involving or in the vicinity of the inferior aspect of the frontal horn and in the region of the caudate head. Neuronavigation can be of assistance during surgery and avoid critical misdirection 1).
In the non-contrast brain CT image you provided, the ventriculoperitoneal shunt catheter is clearly visible, inserted into the frontal horn of the right lateral ventricle.
Regarding the distance between the catheter tip and the foramen of Monro:
The foramen of Monro (or interventricular foramen) is located approximately at the midline, at the junction between the frontal horn and the body of the lateral ventricle, near the thalamic plane.
In this axial image, the catheter tip is located within the frontal horn, anterior and slightly lateral to the foramen of Monro.
Approximate visual estimation: the catheter tip is at a distance of about 1.5 to 2 cm from the foramen of Monro, following the anteroposterior axis of the lateral ventricle.