midbrain


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Related to midbrain: Midbrain tegmentum

mesencephalon

 [mes″en-sef´ah-lon]
1. the short part of the brainstem just above the pons; it contains the nerve pathways between the cerebral hemispheres and the medulla oblongata, as well as nuclei (relay stations or centers) of the third and fourth cranial nerves. The center for visual reflexes, such as moving the head and eyes, is located here.
The mesencephalon (midbrain). From Applegate, 2000.
2. the middle of the three primary brain vesicles of the embryo; called also midbrain. adj., adj mesencephal´ic.

mes·en·ceph·a·lon

(mes-en-sef'ă-lon), [TA]
That part of the brainstem developing from the middle of the three primary cerebral vesicles of the embryo (the caudal of these being the rhombencephalon or hindbrain, the rostral the prosencephalon or forebrain). In the adult, the mesencephalon is characterized by the unique conformation of its roof plate, the lamina tecti (tectal plate [TA] or quadrigeminal plate [TAalt]). composed of the bilaterally paired superior and inferior colliculus, and by the massive paired prominence of the crus cerebri at its anterolateral (ventrolateral) surface. On transverse section, its patent central canal, the cerebral aqueduct, is surrounded by a prominent ring of gray matter poor in myelinated fibers; the periaqueductal gray is adjoined by the myelin-rich mesencephalic tegmentum, and covered posteriorly (dorsally) by the mesencephalic tectal plate. Prominent cell groups of the mesencephalon include the motor nuclei of the trochlear and oculomotor nerves, the red nucleus, and the substantia nigra.
Synonym(s): midbrain vesicle ☆ , midbrain
[mes- + G. enkephalos, brain]

midbrain

/mid·brain/ (mid´brān) mesencephalon.

midbrain

midbrain

The part of the brain stem located below the cerebral cortex (joining the diencephalon (thalamus and hypothalamus)) and above the hindbrain (arising from the pons/metencephalon).

Components
Tectum/corpora quadrigemina, tegmentum, cerebral aqueduct, cerebral peduncles, substantia nigra, various nuclei and fasciculi.

Functions
Associated with motor pathways via the basal ganglia; motivation and habituation via dopaminergic pathways via substantia nigra; helps relay information for vision and hearing.

mes·en·ceph·a·lon

(mes'en-sef'ă-lon) [TA]
That part of the brainstem developing from the middle of the three primary cerebral vesicles of the embryo. In an adult, the mesencephalon is characterized by the unique conformation of its roof plate, the lamina of the mesencephalic tectum, composed of the bilaterally paired superior and inferior colliculi, and by the massive paired prominence of the crus cerebri at its ventral surface. Prominent cell groups of the mesencephalon include the motor nuclei of the trochlear and oculomotor nerves, the red nucleus, and the substantia nigra.
Synonym(s): midbrain.
[G. mes- middle + G. enkephalos, brain]

midbrain

or

mesencephalon

that part of the brain lying between the forebrain and hindbrain. It contains the optic lobe and is particularly concerned with hearing and sight. see FOREBRAIN, HINDBRAIN.

mesencephalon

; midbrain part of brainstem containing the substantia nigra

mes·en·ceph·a·lon

(mes'en-sef'ă-lon) [TA]
That part of the brainstem developing from the middle of the three primary cerebral vesicles of the embryo. In an adult, the mesencephalon is characterized by the unique conformation of its roof plate, the lamina of the mesencephalic tectum, composed of the bilaterally paired superior and inferior colliculi, and by the massive paired prominence of the crus cerebri at its ventral surface.
Synonym(s): midbrain.
[G. mes- middle + G. enkephalos, brain]

midbrain (mid´brān),

n the portion of the brain located superior to the pons and medulla and containing the motor nuclei of the ocular motor and trochlear nerves. It also contains the major pathways and decussations of fibers from the cerebrum and cerebellum.

midbrain

the short part of the brainstem just rostral to the pons. It contains the nerve pathways between the cerebral hemispheres and the medulla oblongata, and also contains nuclei of the third and fourth cranial nerves. The centers for visual and auditory reflexes, such as moving the head and eyes, are located in the midbrain. Called also mesencephalon.

midbrain lesion
causes spastic paresis or paralysis, tremor, nystagmus, opisthotonos and depression or coma.
midbrain syndrome
mental depression, ipsilateral oculomotor nerve deficits, and spastic weakness or paralysis of all four limbs or those on the contralateral side of the body. May be caused by cranial trauma, thiamin deficiency, brain tumors, and degenerative or inflammatory disorders of the mesencephalon.
References in periodicals archive ?
Cluster breathing occurs with midbrain and pontine damage--respirations are irregular and rapid, grouped between periods of apnoea.
Pathogenesis is due to lymphocytic infiltration of perivascular neuronal tissue with a predilection for gray matter, including thalamus, midbrain, and cerebellum (11).
The changes in the expression of auditory-related genes in the midbrain of repeated blast-exposed mice are shown in Table 4.
In summary, CLIPPERS is a newly described condition that should be considered by pathologists when a prominent lymphocytic inflammatory infiltrate is encountered in specimens of the brainstem, spinal cord, midbrain, or cerebellum.
While we can not prove its causality, the relationship between ventricular and peduncular expansion indicates that ventricular expansion coincides with the size of the corticospinal tract in the midbrain.
During days 37-61, the dorsal midbrain and nape pigment increased, leaving an unpigmented area along the midline (Fig.
These drugs have multiple mechanisms of benefit, including acting on the midbrain to reduce the sensation of shortness of breath, decreasing oxygen consumption by reducing muscle activity, suppressing cough, reducing chemoreceptor sensitivity to carbon dioxide, and decreasing cardiac preload and sympathetic tone.
Activin A, a glycoprotein produced in the central nervous system (5), enhances the survival of midbrain and hippocampal neurons (4-7), decreases ischemic brain injury in infant rats (4, 8), and shields striatal and midbrain neurons against neurotoxic damage (4, 9).
Ventral tegmental area (see graphic): The midbrain region containing dopamine cell bodies that project to various parts of the forebrain, including the nucleus accumbens.
A region in the midbrain responds to new information and this stimulates our brain's reward, motivation and memory systems.
Specific topics include active uptake system of L-DOPA in the central nervous system, physiological release of DOPA, the possible existence of DOPA recognition sites, blood pressure regulation in lower brainstem and responses to levodopa and glutamate, neuroprotective and neurotoxic effects of L-DOPA in rat midbrain dopaminergic neurons in culture, and effect of neonatal treatment with monosodium glutamate on dopamine and DOPA neurons in the medial basal hypothalamus of rats.