Colliculi | Brain Parts

Colliculi

Ashley Davidoff MD

Introduction

The corpora quadrigemina ( Latin for for “quadruplet bodies”) consist of 4 bodies called colliculi The four colliculi are named supewrior and inferior colliculi and are located on the roof or tectum on the the dorsal aspect of the midbrain. The corpora quadrigemina are reflex centers involving vision and hearing.

Superior Colliculi

Located beneath the thalamus, and adjacent to the inferior colluculi. It is eresponsible for eye movements and eye-head coordination as well as some oculomotor movements.

Inferior Colliculi

Parallel to the superior colliculi in the midbrain, the inferior colliculi processes vertical and horizontal information in the auditory pathway. The interior colliculi integrate and filter information.

Colliculi (purple)

The anterior border of the midbrain incorporates the cerbral peduncles(green), and the substantia nigra (black – just posterior to the peduncles. Between the substantia nigra and the aqueduct is an area of the midbrain called the tegmentum (floor of the midbrain) The posterior end of the midbrain is bordered by the colliculi (purple) in the tectum (roof) of the midbrain.

Colliculi Axial Projection

The midbrain in transverse plane illustrates the component structures, with the image reminiscent of the face of a baby pig.. Anteriorly the cerebral peduncles are followed by the substantia nigra, and the collilculi The anterior border of the midbrain incorporates the cerebral peduncles, and the substantia nigra (black – just posterior to the peduncles). Between the substantia nigra and the aqueduct is an area of the midbrain called the tegmentum (floor of the midbrain) Within the tegmentum other structures include red nuclii, oculomotor nuclii, periaquaductal gray, and the aqueduct of Sylvius which is border forming between the tegmentum anteriorly and the tectum (roof) posteriorly. The posterior end of the midbrain is bordered by the colliculi in the tectum.

Axial Anatomic Specimen through the Midbrain

Region of the Superior Colliculus

The anatomic section is an axial slice through the brain showing the structures of the midbrain. The most anterior structures of the midbrain are the cerebral peduncles followed by the substantia nigra, red nucleus, periaquaductal gray (PAG or central gray), aqueduct of Sylvius and finally the superior colliculus. Structures that are related to the midbrain anteriorly are the mamillary bodies and the optic tract. The hippocampus is positioned posterolaterally and the superior aspect of the cerebellum is seen posteriorly.

Courtesy Department of Anatomy and Neurobiology at Boston University School of Medicine Dr. Jennifer Luebke , and Dr. Douglas Rosene 97140b03c.9

Whole Mount of the Midbrain in Axial Projection

The mounted and stained midbrain in transverse plane illustrates the component structures. The anterior border of the midbrain incorporates the cerebral peduncles (CP), and the substantia nigra (SN). Between the substantia nigra and the aqueduct (teal arrow) is an area of the midbrain called the tegmentum (floor of the midbrain) Within the tegmentum other structures include red nuclii (RNu), oculomotor nucleus (Nu3), periaquaductal gray (PAG), and the aqueduct of Sylvius which is border forming between the tegmentum anteriorly and the tectum (roof) posteriorly. The posterior end of the midbrain is bordered by the colliculi in the tectum. Note also the paired mamillary bodies anteriorly (MB) and the medial geniculate body (MG) posterolaterally

Courtesy Department of Anatomy and Neurobiology at Boston University School of Medicine Dr. Jennifer Luebke , and Dr. Douglas Rosene 98483L.8

The Cerebral arteries Characteristically Surround the Midbrain

The MRI T2 weighted series now focuses on another very characteristic feature of the midbrain in that it is surrounded by the anterior and posterior cerebral circulations, and in this case portions of the arteries are seen with parts of the middle cerebral seen anteriorly and parts of the posterior cerebral seen posteriorly

Sagittal Plane

Basic Divisions of the Midbrain

Tegmentum and Tectum

Cerebral Peduncles, Cerebral Crura and Colliculli

The midbrain consists of a larger anterior portion consisting of the cerebral peduncles, (green) the substantia nigra (black) and the tegmentum (light orange) that extends to the aqueduct (thin gray line) The posterior portion called tectum (orange) contains the colliculi (purple) which are the most posterior portions of the midbrain. brain anatomy neuroanatomy midbrain tegmentum colliculi tectum cerebral peduncle aqueduct of Sylvius conceptual diagram MRI principles

Image provided by Philips Medical Systems Enhanced by Davidoff art Courtesy Ashley Davidoff MD 92141.3kb01ba02b02.8s

The Colliculi in Coronal Section

The T2 weighted MRI in the coronal plane reveals the colliculi of the midbrain (aka quadrigeminal plate) which are part of the midbrain