The midbrain acts as a relay system, transmitting information needed for vision and hearing. It also plays an important role in motor movements, pain and the sleep-wake cycle.
The midbrain, also known as the midbrain, is part of the central nervous system. It is located below the cerebral cortex and at the top of the brainstem.
The midbrain is the upper region of the brainstem.
Your brainstem connects your brain to your cervical spinal cord (neck) and consists of three main parts:
- elongated medulla
(Sometimes themidbrainalso considered part of the brainstem.)
Together, these three parts regulate various involuntary functions such as breathing, heart rate and blood pressure. Your brainstem also plays a crucial role in sleep and consciousness.
Your midbrain can then be divided into two main parts:
- The roof: This anterior surface of the midbrain contains numerous structures, including the reticular formation, the periaqueductal gray matter (PAG), certain cranial nerve nuclei, sensory and motor nerve pathways (the corticospinal and spinothalamic tracts), the red nucleus, the substantia nigra, and the ventral tegmental area (VTA).
- The roof: The posterior surface of the midbrain contains the quadrigeminal bodies, which contain clusters of nerve cells called the superior and inferior colliculus.
The midbrain is about 1.5 centimeters long and lies between the diencephalon (which includes the thalamus and thalamus).hypothalamus) and the bridge.
The midbrain is supplied with blood by the basilar artery and its branches, including the posterior and superior cerebellar arteries.
There are also twobrain nervesno midbrain present:
- ON. oculomotorius (Hirnnerv III)
- OTrochlear nerve (cranial nerve IV).
The midbrain is a complex region of the brainstem that performs many functions.
Structures within the tegment perform these specific functions:
- net-like structure: This highly diverse and integrative area contains a network of nuclei responsible for many vital functions, including arousal, awareness, sleep-wake cycles, coordination of certain movements, and cardiovascular control.
- Periaqueductal gray matter (PAG).: This area plays a key role in processing pain signals, autonomic functioning, and behavioral responses to fear and anxiety. Recently, this structure has been implicated in the control of defense responses associated withPost Traumatic Stress Disorder (PTSD).
- The Brain's Friends: The oculomotor nerve nuclei are responsible for controlling the pupil and most eye movements. Trochlear nerve nuclei innervate the superior oblique muscle of the eye, which abducts, depresses, and inwardly rotates the eye.
- spinothalamic treatment: this main nerve pathway carries information about pain and temperature sensations from the body to the brain's thalamus.
- Corticospinal Treatment: this main nerve pathway carries movement-related information from the brain to the spinal cord.
- red core: This region is involved in motor coordination. It is called the "red" core because of its pink color, which is due to the presence of iron.
- black substance: This area contains nerve cells that make up the neurotransmitter (brain chemical)dopamine. It serves as a relay station for nerve signals responsible for controlling movement.
- Ventral Tegmental Area (VTA): O contains dopamine-producing cell bodies and plays a key role in the reward system.
nerve cells in itthe superior colliculiVisual signal processingretina of the eyebefore being directed to the occipital lobe at the back of the head. The superior colliculi of the midbrain are also responsible for generating eye movements and neck muscle activity.
Othe lower part of the neckit is responsible for processing auditory signals (hearing) before they pass through the thalamus and finally to the primary auditory cortex in the temporal lobe. In addition to sound localization, the inferior colliculus is responsible for:
- Creating the startle response
- Alignment of the body to specific stimuli
- Distinction between pitch and rhythm
The midbrain can be affected by a number of different pathological processes, includingAVCB. a tumor, a demyelinating process, an infection, or a neurodegenerative disease.
Examples of specific conditions are:
Oculomotor (third) nerve palsy
Any injury to the midbrain (stroke, tumor, inflammation, infection) can damage the oculomotor nerve, resulting in an eye that looks down and out.
Other symptoms of eye paralysis include:
- a dilated pupil
- drooping eyelid
- Diplopia (double vision)
- inability to adapt
Study palsy of the (fourth) nerve
As with oculomotor nerve palsy, a midbrain injury can cause trochlear nerve palsy. Symptoms of trochlear nerve palsy include:
- upward deviation of the eye
- blurry vision
- Tilting the head to the unaffected side to compensate for visual changes
There are five classic midbrain syndromes:
- Parinaud's syndrome: Also known as dorsal midbrain syndrome, this condition usually results from the mass effect of an adjacent brain.Pineal glandTumor. Symptoms may include looking down at rest, pupils that respond poorly to light, eyelid retraction, and convergence retractionNystagmus(if you have uncontrollable, jerky eye movements)
- Weber's syndrome: This condition, also known as midbrain stroke syndrome and alternating superior hemiplegia, is caused by a stroke in a branch of the basilar or posterior cerebral artery. This results in ipsilateral third nerve palsy (same side) and contralateral weakness (opposite side).
- Claude's syndrome: This condition results from a stroke in the dorsal (upper) tegmentum of the midbrain. This leads to ipsilateral oculomotor palsy with contralateral cerebellumAtaxia(uncoordinated movements).
- benedict syndrome: Like Claude's syndrome, this condition results from a stroke in the tegmentum of the midbrain. In addition to oculomotor nerve palsy and ataxia, there is damage to the corticospinal tract, resulting in contralateral weakness.
- Nothnagel's syndrome: this condition usually results from a midbrain tumor, such as aGlioma. Symptoms include unilateral or bilateral oculomotor nerve palsy and ipsilateral cerebellar ataxia.
Multiple Sclerosis (MS)occurs when a person's own immune system attacks the insulating covering (myelin) of nerve fibers in the brain, spinal cord, and/or eyes.
When the brainstem is affected, the patient may experience the following symptoms:
- Visual disturbances, including diplopia
- Difficulty swallowing (dysphagia)
- Difficulty speaking (dysarthria)
- Altered sensation or weakness of the face
- hearing difficulties
- Headaches that resemble a migraine
- Rarely, problems affecting vital signs (for example, breathing or heart rate)
MS brain lesions and their implications
Parkinson diseaseit is a progressive neurological condition (meaning the symptoms are subtle at first and slowly get worse). It is caused by the death of dopamine-producing nerve cells in the substantia nigra.
As a result of this dopamine depletion, severalsymptomscan develop, including:
- resting tremors
- slowness of movement
- Stiffness and shuffling gait
- small handwriting
- sleep disorders
In rare cases, a person's midbrain does not form properly during fetal development. Midbrain dysplasia is one such genetic malformation that results in microcephaly, spasticity, intellectual disability, and seizures.
Treatment depends on the specific pathology affecting the midbrain.
For example, patients withTumor cerebralaffecting the midbrain may require surgery, radiation and/or chemotherapy.
in the same way aischemic stroke(caused by a blood clot) in the midbrain may warrant treatment with a drug called a "clot-dissolving" drugTissue-type plasminogen activator. Also, a patient needs a comprehensive evaluation to clarify the cause of the stroke (eg, heart disease, atrial fibrillation, etc.).
From there, several therapies can be indicated, including medication, such asanticoagulantsand rehabilitation therapy (eg, physiotherapy and occupational therapy).
MS-related inflammationof the midbrain usually requires short-term treatment with corticosteroids and long-term treatment with adisease modifying therapy.rehabilitation therapyTreating the symptoms is often warranted.
The treatment ofParkinson diseaserequires participation in physical and occupational therapy and use of medications designed to replace dopamine or optimize the effects of dopamine in the brain (eg, levodopa).
How brain tumors are treated
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VonColleen Doherty, MD
Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.
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What is midbrain anatomy and physiology? ›
midbrain, also called mesencephalon, region of the developing vertebrate brain that is composed of the tectum and tegmentum. The midbrain serves important functions in motor movement, particularly movements of the eye, and in auditory and visual processing.What are the 3 functions of the midbrain? ›
The midbrain functions as a relay system, transmitting information necessary for vision and hearing. It also plays an important role in motor movement, pain, and the sleep/wake cycle. The midbrain, also called the mesencephalon, is a part of the central nervous system.What important structure is located in the midbrain? ›
On the posterior surface of the midbrain, there is a structure called the corpora quadrigemina. It is composed of superior and inferior colliculi. Superior colliculi are two multilayers structures located below the thalamus and around the pineal gland and involved in processing visual information.
Your medulla is the bottom-most part of your brain, connecting to your spinal cord through the foramen magnum, an opening at the bottom of your skull. Just above your medulla is your pons, which is just below the central structures in your brain.What are the 5 parts of the midbrain? ›
The principal regions of the midbrain are the tectum, the cerebral aqueduct, tegmentum, and the cerebral peduncles. Rostrally the midbrain adjoins the diencephalon (thalamus, hypothalamus, etc.), while caudally it adjoins the hindbrain (pons, medulla and cerebellum).What are the four lobes of midbrain? ›
Traditionally, each of the hemispheres has been divided into four lobes: frontal, parietal, temporal and occipital.Which actions are controlled by midbrain? ›
Involuntary actions are under the voluntary control of the medulla oblongata which is generally referred to as the midbrain. The involuntary movements are characterised by relatively slower speed. The best example of this movement is the beating movement of the human heart.What is an interesting fact about the midbrain? ›
Of the activities the midbrain controls one on the most important is the coordination of our eyeballs. Each eye sees the world from an angle different than the other. The midbrain controls eyeball movement so that these two different images can be "fused" into a single image which appears three-dimensional.Is the midbrain responsible for sleep? ›
The basal forebrain, near the front and bottom of the brain, also promotes sleep and wakefulness, while part of the midbrain acts as an arousal system.What cells are in the midbrain? ›
The adult midbrain contains two main anatomically defined populations of dopaminergic neurons, located in the ventral tegmental area (VTA) and in the substantia nigra pars compacta (SNc) (Björklund and Dunnett, 2007).
Is the midbrain involved in memory? ›
The dopaminergic midbrain participates in human episodic memory formation: evidence from genetic imaging. J Neurosci. 2006 Feb 1;26(5):1407-17. doi: 10.1523/JNEUROSCI.What neurons are in the midbrain? ›
Midbrain dopamine regions contain at least three neuronal phenotypes: dopaminergic, GABAergic, and glutamatergic.What are the 3 main centers in the medulla? ›
The medulla contains the cardiac, respiratory, vomiting and vasomotor centers, and therefore deals with the autonomic functions of breathing, heart rate and blood pressure as well as the sleep–wake cycle.Is the medulla in the midbrain? ›
The cone-shaped medulla oblongata sits beneath the midbrain and pons. It contains both white and gray matter.What does pons do in the brain? ›
Your pons is a part of your brainstem, a structure that links your brain to your spinal cord. It handles unconscious processes and jobs, such as your sleep-wake cycle and breathing. It also contains several junction points for nerves that control muscles and carry information from senses in your head and face.What is midbrain psychology definition? ›
n. a relatively small region of the upper brainstem that connects the forebrain and hindbrain. It contains the tectum (and associated inferior and superior colliculi), tegmentum, and substantia nigra. Also called mesencephalon.What is the midbrain quizlet? ›
The midbrain; a region of the brain that surrounds the cerebral aqueduct; includes the tectum and the tegmentum. Tectum. The dorsal part of the midbrain; includes the superior and inferior colliculi.What is the midbrain simply psychology? ›
The second area of the brain is the midbrain, which lies on top of the brainstem. The midbrain is involved in auditory and visual processing (Peters, 2017). It is also responsible for eye movement. There are three parts to the midbrain: the colliculi, the tegmentum, and the cerebral peduncles.
The primary function is to integrate motor, sensory, and cognitive performances between the cerebral cortex on one side of the brain to the same region on the other side.Are emotions in the midbrain? ›
Emotions are therefore regulated by a broad range of subcortical and cortical structures, with a critical role being played by subcortical nuclei in the pontine and midbrain tegmentum (Nauta, 1958; Parvizi and Damasio, 2001), as well as by autonomic and cardiorespiratory nuclei in the medulla (Edlow et al., 2016).
Which are of the midbrain controls emotion? ›
Amygdala. The amygdala helps coordinate responses to things in your environment, especially those that trigger an emotional response.What are the 3 parts of the midbrain? ›
The midbrain is the topmost part of the brainstem, the connection central between the brain and the spinal cord. There are three main parts of the midbrain - the colliculi, the tegmentum, and the cerebral peduncles.What does the midbrain regulate? ›
Midbrain: The top part of the brainstem is crucial for regulating eye movements. Pons: The middle portion of the brainstem coordinates facial movements, hearing and balance. Medulla oblongata: The bottom part of the brainstem helps regulate your breathing, heart rhythms, blood pressure and swallowing.Is the brain stem part of the midbrain? ›
The brainstem is the structure that connects the cerebrum of the brain to the spinal cord and cerebellum. It is composed of three sections in descending order: the midbrain, pons, and medulla oblongata.