Midbrain tectum
Encyclopedia
The tectum is a region of the brain
, specifically the dorsal part of the mesencephalon
(midbrain). This is contrasted with the tegmentum
, which refers to the region ventral to the ventricular system
. It is responsible for auditory and visual reflexes.
It is derived in embryonic development from the alar plate
of the neural tube
.
and the superior colliculi
.
Both colliculi also have descending projections to the paramedian pontine reticular formation
and spinal cord
, and thus can be involved in responses to stimuli faster than cortical processing would allow. Collectively the colliculi are referred to as the corpora quadrigemina
.
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
, specifically the dorsal part of the mesencephalon
Mesencephalon
The midbrain or mesencephalon is a portion of the central nervous system associated with vision, hearing, motor control, sleep/wake, arousal , and temperature regulation....
(midbrain). This is contrasted with the tegmentum
Tegmentum
The tegmentum is a general area within the brainstem. It is located between the ventricular system and distinctive basal or ventral structures at each level...
, which refers to the region ventral to the ventricular system
Ventricular system
The ventricular system is a set of structures containing cerebrospinal fluid in the brain. It is continuous with the central canal of the spinal cord.-Components:The system comprises four ventricles:* right and left lateral ventricles* third ventricle...
. It is responsible for auditory and visual reflexes.
It is derived in embryonic development from the alar plate
Alar plate
The alar plate is a neural structure in the embryonic nervous system, part of the dorsal side of neural tube, that involves the communication of general somatic and general visceral sensory impulses. The caudal part later becomes sensory axon part of the spinal cord.-External links:* *...
of the neural tube
Neural tube
In the developing vertebrate, the neural tube is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord...
.
Colliculi
In adult humans it is present only in the mesencephalon as the inferiorInferior colliculus
The inferior colliculus is the principal midbrain nucleus of the auditory pathway and receives input from several more peripheral brainstem nuclei in the auditory pathway, as well as inputs from the auditory cortex...
and the superior colliculi
Superior colliculus
The optic tectum or simply tectum is a paired structure that forms a major component of the vertebrate midbrain. In mammals this structure is more commonly called the superior colliculus , but, even in mammals, the adjective tectal is commonly used. The tectum is a layered structure, with a...
.
- The superior colliculus is involved in preliminary visual processingVisual perceptionVisual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
and control of eye movements. In non-mammalian vertebrates it serves as the main visual area of the brain, functionally analogous to the visual areas of the cerebral cortexCerebral cortexThe cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
in mammals.
- The inferior colliculus is involved in auditory processingAuditory systemThe auditory system is the sensory system for the sense of hearing.- Outer ear :The folds of cartilage surrounding the ear canal are called the pinna...
. It receives input from various brain stem nuclei and projects to the medial geniculate nucleusMedial geniculate nucleusThe Medial Geniculate Nucleus or Medial Geniculate Body is part of the auditory thalamus and represents the thalamic relay between the inferior colliculus and the auditory cortex...
of the thalamusThalamusThe thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
, which relays auditory information to the primary auditory cortexPrimary auditory cortexThe primary auditory cortex is the region of the brain that is responsible for the processing of auditory information. Corresponding roughly with Brodmann areas 41 and 42, it is located on the temporal lobe, and performs the basics of hearing—pitch and volume...
.
Both colliculi also have descending projections to the paramedian pontine reticular formation
Paramedian pontine reticular formation
The paramedian pontine reticular formation, or PPRF, is part of the pontine reticular formation, a brain region without clearly defined borders in the center of the pons. It is involved in the coordination of eye movements, particularly horizontal gaze and saccades.- Input, Output, and Function...
and spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
, and thus can be involved in responses to stimuli faster than cortical processing would allow. Collectively the colliculi are referred to as the corpora quadrigemina
Corpora quadrigemina
In the brain, the corpora quadrigemina are the four colliculi—two inferior, two superior—located on the tectum of the dorsal aspect of the midbrain.They are respectively named the inferior and superior colliculus....
.
