Brainstem - wikipedia Brainstem This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( January 2013 ) Neuroscience portal Brainstem The three distinct parts of the brainstem are colored in this sagittal section of a human brain. Details Part of Brain Parts Medulla, Pons, Midbrain Identifiers Latin truncus encephali MeSH D001933 NeuroNames 2052, 236 NeuroLex ID birnlex_1565 TA A14. 1.03. 009 FMA 79876 Anatomical terms of neuroanatomy ( edit on Wikidata ) The brainstem ( or brain stem ) is the posterior part of the brain, adjoining and structurally continuous with the spinal cord. In the human brain the brainstem includes the midbrain, and the pons and medulla oblongata of the hindbrain. Sometimes the diencephalon, the caudal part of the forebrain, is included. The brainstem provides the main motor and sensory innervation to the face and neck via the cranial nerves. Of the twelve pairs of cranial nerves, ten pairs come from the brainstem. The brainstem is an extremely important part of the brain as the nerve connections of the motor and sensory systems from the main part of the brain to the rest of the body pass through the brainstem. This includes the corticospinal tract ( motor ), the dorsal column - medial lemniscus pathway ( fine touch, vibration sensation, and proprioception ), and the spinothalamic tract ( pain, temperature, itch, and crude touch ). The brainstem also plays an important role in the regulation of cardiac and respiratory function. It also regulates the central nervous system, and is pivotal in maintaining consciousness and regulating the sleep cycle. The brainstem has many basic functions including heart rate, breathing, sleeping, and eating. Contents 1 Structure 1.1 Midbrain 1.2 Hindbrain 1.2. 1 Pons 1.2. 2 Medulla oblongata 1.3 Ventral view of medulla and pons 1.4 Dorsal view of medulla and pons 2 Development 3 Blood supply 4 Cranial nerves 5 Function 6 Clinical significance 7 Additional images 8 See also 9 References 10 External links Structure Midbrain Structures of the brainstem Cross-section of the midbrain at the level of the superior colliculus. Cross-section of the midbrain at the level of the inferior colliculus. Main article : Midbrain The midbrain is divided into three parts : tectum, tegmentum, and the ventral tegmentum. The tectum ( Latin : roof ), which forms the ceiling. The tectum comprises the paired structure of the superior and inferior colliculi and is the dorsal covering of the cerebral aqueduct. The inferior colliculus, is the principal midbrain nucleus of the auditory pathway and receives input from several peripheral brainstem nuclei, as well as inputs from the auditory cortex. Its inferior brachium ( arm - like process ) reaches to the medial geniculate nucleus of the diencephalon. Superior to the inferior colliculus, the superior colliculus marks the rostral midbrain. It is involved in the special sense of vision and sends its superior brachium to the lateral geniculate body of the diencephalon. The tegmentum which forms the floor of the midbrain, is ventral to the cerebral aqueduct. Several nuclei, tracts, and the reticular formation are contained here. The ventral tegmental area ( VTA ) is composed of paired cerebral peduncles. These transmit axons of upper motor neurons. The midbrain consists of : Periaqueductal gray : The area of gray matter around the cerebral aqueduct, which contains various neurons involved in the pain desensitization pathway. Neurons synapse here and, when stimulated, cause activation of neurons in the nucleus raphe magnus, which then project down into the posterior grey column of the spinal cord and prevent pain sensation transmission. Oculomotor nerve nucleus : This is the third cranial nerve nucleus. Trochlear nerve nucleus : This is the fourth cranial nerve. Red nucleus : This is a motor nucleus that sends a descending tract to the lower motor neurons. Substantia nigra pars compacta : This is a concentration of neurons in the ventral portion of the midbrain that uses dopamine as its neurotransmitter and is involved in both motor function and emotion. Its dysfunction is implicated in Parkinson 's disease. Reticular formation : This is a large area in the midbrain that is involved in various important functions of the midbrain. In particular, it contains lower motor neurons, is involved in the pain desensitization pathway, is involved in the arousal and consciousness systems, and contains the locus coeruleus, which is involved in intensive alertness modulation and in autonomic reflexes. Central tegmental tract : Directly anterior to the floor of the fourth ventricle, this is a pathway by which many tracts project up to the cortex and down to the spinal cord. Ventral tegmental area : A dopaminergic nucleus located close to the midline on the floor of the midbrain. Rostromedial tegmental nucleus : A GABAergic nucleus located adjacent to the ventral tegmental area. Hindbrain The pons and medulla oblongata are parts of the hindbrain that form much of the brainstem. Pons Main article : Pons This section needs expansion. You can help by adding to it. ( April 2014 ) The pons lies between the medulla oblongata and the midbrain. It contains tracts that carry signals from the cerebrum to the medulla and to the cerebellum and also tracts that carry sensory signals to the thalamus. The pons is connected to the cerebellum by the cerebellar peduncles. The pons houses the respiratory pneumotaxic center and apneustic center that make up the pontine respiratory group in the respiratory center. The pons co-ordinates activities of the cerebellar hemispheres. Medulla oblongata Main article : Medulla oblongata This section needs expansion. You can help by adding to it. ( April 2014 ) The medulla oblongata often just referred to as the medulla, is the lower half of the brainstem continuous with the spinal cord. Its upper part is continuous with the pons. The medulla contains the cardiac, dorsal and ventral respiratory groups, and vasomotor centres, dealing with heart rate, breathing and blood pressure. Another important medullary structure is the area postrema whose functions include the control of vomiting. Ventral view of medulla and pons Cross-section of the middle pons ( at the level of cranial nerve V ). Cross-section of the inferior pons ( at the level of the facial genu ). Cross-section of the rostral ( superior ) medulla. Cross-section of the middle medulla. Cross-section of the inferior medulla. In the medial part of the medulla is the anterior median fissure. Moving laterally on each side are the medullary pyramids. The pyramids contain the fibers of the corticospinal tract ( also called the pyramidal tract ), or the upper motor neuronal axons as they head inferiorly to synapse on lower motor neuronal cell bodies within the anterior grey column of the spinal cord. The anterolateral sulcus is lateral to the pyramids. Emerging from the anterolateral sulci are the CN XII ( hypoglossal nerve ) rootlets. Lateral to these rootlets and the anterolateral sulci are the olives. The olives are swellings in the medulla containing underlying inferior nucleary nuclei ( containing various nuclei and afferent fibers ). Lateral ( and dorsal ) to the olives are the rootlets for CN IX ( glossopharyngeal ), CN X ( vagus ) and CN XI ( accessory nerve ). The pyramids end at the pontine medulla junction, noted most obviously by the large basal pons. From this junction, CN VI ( abducens nerve ), CN VII ( facial nerve ) and CN VIII ( vestibulocochlear nerve ) emerge. At the level of the midpons, CN V ( the trigeminal nerve ) emerges. Cranial nerve III ( the oculomotor nerve ) emerges ventrally from the midbrain, while the CN IV ( the trochlear nerve ) emerges out from the dorsal aspect of midbrain. Between the two pyramids can be seen a decussation of fibres which marks the transition from the medulla to the spinal cord. The medulla is above the decussation and the spinal cord below. Dorsal view of medulla and pons The most medial part of the medulla is the posterior median sulcus. Moving laterally on each side is the fasciculus gracilis, and lateral to that is the fasciculus cuneatus. Superior to each of these, and directly inferior to the obex, are the gracile and cuneate tubercles, respectively. Underlying these are their respective nuclei. The obex marks the end of the fourth ventricle and the beginning of the central canal. The posterior intermediate sulcus separates the fasciculus gracilis from the fasciculus cuneatus. Lateral to the fasciculus cuneatus is the lateral funiculus. Superior to the obex is the floor of the fourth ventricle. In the floor of the fourth ventricle, various nuclei can be visualized by the small bumps that they make in the overlying tissue. In the midline and directly superior to the obex is the vagal trigone and superior to that it the hypoglossal trigone. Underlying each of these are motor nuclei for the respective cranial nerves. Superior to these trigones are fibers running laterally in both directions. These fibers are known collectively as the striae medullares. Continuing in a rostral direction, the large bumps are called the facial colliculi. Each facial colliculus, contrary to their names, do not contain the facial nerve nuclei. Instead, they have facial nerve axons traversing superficial to underlying abducens ( CN VI ) nuclei. Lateral to all these bumps previously discussed is an indented line, or sulcus that runs rostrally, and is known as the sulcus limitans. This separates the medial motor neurons from the lateral sensory neurons. Lateral to the sulcus limitans is the area of the vestibular system, which is involved in special sensation. Moving rostrally, the inferior, middle, and superior cerebellar peduncles are found connecting the midbrain to the cerebellum. Directly rostral to the superior cerebellar peduncle, there is the superior medullary velum and then the two trochlear nerves. This marks the end of the pons as the inferior colliculus is directly rostral and marks the caudal midbrain. Middle cerebellar peduncle is located inferior and lateral to the superior cerebellar peduncle, connecting pons to the cerebellum. Likewise, inferior cerebellar peduncle is found connecting the medulla oblongata to the cerebellum. Development The adult human brainstem emerges from two of the three primary vesicles formed of the neural tube. The mesencephalon is the second of the three primary vesicles, and does not further differentiate into a secondary vesicle. This will become the midbrain. The third primary vesicle, the rhombencephalon ( hindbrain ) will further differentiate into two secondary vesicles, the metencephalon and the myelencephalon. The metencephalon will become the cerebellum and the pons. The more caudal myelencephalon will become the medulla. Blood supply The main supply of blood to the brainstem is provided by the basilar arteries and the vertebral arteries. Cranial nerves This section needs expansion. You can help by adding to it. ( October 2016 ) Main article : cranial nerves Ten of the twelve pairs of cranial nerves either target or are sourced from the brainstem. The nuclei of the oculomotor nerve ( III ) and trochlear nerve ( IV ) are located in the midbrain. The nuclei of the trigeminal nerve ( V ), abducens nerve ( VI ), facial nerve ( VII ) and vestibulocochlear nerve ( VIII ) are located in the pons. The nuclei of the glossopharyngeal nerve ( IX ), vagus nerve ( X ), accessory nerve ( XI ) and hypoglossal nerve ( XII ) are located in the medulla. The fibers of these cranial nerves exit the brainstem from these nuclei. Function There are three main functions of the brainstem : The brainstem plays a role in conduction. That is, all information relayed from the body to the cerebrum and cerebellum and vice versa must traverse the brainstem. The ascending pathways coming from the body to the brain are the sensory pathways and include the spinothalamic tract for pain and temperature sensation and the dorsal column - medial lemniscus pathway ( DCML ) including the gracile fasciculus and the cuneate fasciculus for touch, proprioception, and pressure sensation. The facial sensations have similar pathways, and will travel in the spinothalamic tract and the DCML. Descending tracts are the axons of upper motor neurons destined to synapse on lower motor neurons in the ventral horn and posterior horn. In addition, there are upper motor neurons that originate in the brainstem 's vestibular, red, tectal, and reticular nuclei, which also descend and synapse in the spinal cord. The cranial nerves III - XII emerge from the brainstem. These cranial nerves supply the face, head, and viscera. ( The first two pairs of cranial nerves arise from the cerebrum ). The brainstem has integrative functions being involved in cardiovascular system control, respiratory control, pain sensitivity control, alertness, awareness, and consciousness. Thus, brainstem damage is a very serious and often life - threatening problem. Clinical significance Diseases of the brainstem can result in abnormalities in the function of cranial nerves that may lead to visual disturbances, pupil abnormalities, changes in sensation, muscle weakness, hearing problems, vertigo, swallowing and speech difficulty, voice change, and co-ordination problems. Localizing neurological lesions in the brainstem may be very precise, although it relies on a clear understanding on the functions of brainstem anatomical structures and how to test them. Brainstem stroke syndrome can cause a range of impairments including locked - in syndrome. Duret haemorrhages are areas of bleeding in the midbrain and upper pons due to a downward traumatic displacement of the brainstem. Cysts known as syrinxes can affect the brainstem, in a condition called syringobulbia. These fluid - filed cavities can be congenital, acquired or the result of a tumor. Criteria for claiming brainstem death in the UK have developed in order to make the decision of when to stop ventilation of somebody who could not otherwise sustain life. These determining factors are that the patient is irreversibly unconscious and incapable of breathing unaided. All other possible causes must be ruled out that might otherwise indicate a temporary condition. The state of irreversible brain damage has to be unequivocal. There are brainstem reflexes that are checked for by two senior doctors so that imaging technology is unnecessary. The absence of the cough and gag reflexes, of the corneal reflex and the vestibulo - ocular reflex need to be established ; the pupils of the eyes must be fixed and dilated ; there must be an absence of motor response to stimulation and an absence of breathing marked by concentrations of carbon dioxide in the arterial blood. All of these tests must be repeated after a certain time before death can be declared. Additional images The midbrain, pons, and medulla oblongata are labelled on this coronal section of the human brain. Brainstem. Anterior face. Deep dissection Brainstem. Posterior face. Deep dissection Sagittal section of brainstem marking nuclei See also This article uses anatomical terminology ; for an overview, see Anatomical terminology. Triune brain Reptilian brain References Jump up ^ Alberts, Daniel ( 2012 ). Dorland 's illustrated medical dictionary ( 32nd ed. ). Philadelphia, PA : Saunders / Elsevier. p. 248. ISBN 978 - 1 - 4160 - 6257 - 8. Jump up ^ Dorland 's ( 2012 ). Dorland 's Illustrated Medical Dictionary ( 32nd ed. ). Elsevier Saunders. p. 1121. ISBN 978 - 1 - 4160 - 6257 - 8. Jump up ^ Purves, Dale ( 2011 ). Neuroscience ( 5. ed. ). Sunderland, Mass. : Sinauer. p. 740. ISBN 978 - 0 - 87893 - 695 - 3. Jump up ^ Purves, Dale ( 2011 ). Neuroscience ( 5. ed. ). Sunderland, Mass. : Sinauer. p. 725. ISBN 978 - 0 - 87893 - 695 - 3. Jump up ^ Vilensky, Joel ; Robertson, Wendy ; Suarez - Quian, Carlos ( 2015 ). The Clinical Anatomy of the Cranial Nerves : The Nerves of `` On Olympus Towering Top ''. Ames, Iowa : Wiley - Blackwell. ISBN 978 - 1 - 118 - 49201 - 7. Jump up ^ `` Archived copy '' ( PDF ). Archived ( PDF ) from the original on 2013 - 04 - 18. Retrieved 2012 - 11 - 10. CS1 maint : Archived copy as title ( link ) Jump up ^ Dorland 's ( 2012 ). Dorland 's Illustrated Medical Dictionary ( 32nd ed. ). Elsevier. p. 842. ISBN 978 - 1 - 4160 - 6257 - 8. Jump up ^ Black 's Medical Dictionary 39th edition 1999 External links Wikimedia Commons has media related to Brain stem. Comparative Neuroscience at Wikiversity http://www.meddean.luc.edu/lumen/Meded/Neuro/frames/nlBSsL/nl40fr.htm http://biology.about.com/library/organs/brain/blbrainstem.htm http://www.waiting.com/brainanatomy.html http://braininjuryhelp.com/video-tutorial/brain-injury-help-video-tutorial/ http://www.martindalecenter.com/MedicalAnatomy_3_SAD.html NIF Search - Brainstem via the Neuroscience Information Framework Nervous system Central nervous system Meninges Spinal cord Brain Hindbrain Medulla Pons Cerebellum Midbrain Forebrain Diencephalon Retina Optic nerve Cerebrum Limbic system Peripheral nervous system Somatic Sensory nerve Motor nerve Cranial nerve Spinal nerve Autonomic Sympathetic Parasympathetic Enteric Anatomy of the medulla Grey matter Cranial nuclei afferent : Solitary nucleus tract Dorsal respiratory group Gustatory nucleus Vestibular nuclei Lateral Medial Inferior efferent : Hypoglossal nucleus Nucleus ambiguus Dorsal nucleus of vagus nerve Inferior salivatory nucleus Dorsal Gracile nucleus Cuneate nucleus Accessory cuneate nucleus Ventral Ventral respiratory group Arcuate nucleus of medulla Rostral ventromedial medulla Botzinger complex Pre-Bötzinger complex White matter Dorsal Sensory Sensory decussation Medial lemniscus Juxtarestiform body Ascending dorsal longitudinal fasciculus Medial longitudinal fasciculus Motor Descending dorsal longitudinal fasciculus Medial longitudinal fasciculus Ventral Descending tracts Olivocerebellar tract Rubro - olivary tract Surface Front Pyramid Anterior median fissure Anterolateral sulcus Olive Inferior olivary nucleus Back Posterior median sulcus Posterolateral sulcus Area postrema Vagal trigone Hypoglossal trigone Medial eminence Inferior cerebellar peduncle Grey Reticular formation Gigantocellular Parvocellular Ventral Lateral Paramedian Raphe nuclei Obscurus Magnus Pallidus Perihypoglossal nuclei Anatomy of the pons Dorsal / ( tegmentum ) Surface Cerebellopontine angle Superior medullary velum Sulcus limitans Medial eminence Facial colliculus White : Sensory Trapezoid body Trigeminal lemniscus Dorsal trigeminal tract Ventral trigeminal tract Medial lemniscus Lateral lemniscus Medial longitudinal fasciculus Vestibulo - oculomotor fibers Anterior trigeminothalamic tract Central tegmental tract White : Motor Inferior cerebellar peduncle Vestibulocerebellar tract Medial longitudinal fasciculus Vestibulospinal tract Medial vestibulospinal tract Lateral vestibulospinal tract Grey : Cranial nuclei afferent : GSA Trigeminal Principal Spinal Cochlear nucleus Dorsal Anterior Vestibular nuclei Superior efferent : SVE : Trigeminal motor nucleus Facial motor nucleus GSE : Abducens nucleus GVE : Superior salivary nucleus Inferior salivary nucleus Other Apneustic center Pneumotaxic center Parabrachial nuclei Subparabrachial nucleus Medial parabrachial nucleus Lateral parabrachial nucleus Superior olivary nucleus Locus coeruleus Ventral / ( base ) Grey Pontine nuclei White : Motor / descending Corticospinal tract Corticobulbar tract Corticopontine fibers MCP Pontocerebellar fibers Surface Basilar sulcus Other grey : Raphe / reticular Reticular formation Caudal Oral Tegmental Paramedian Raphe nuclei Median Anatomy of the midbrain Tectum ( Dorsal ) Surface Corpora quadrigemina : Inferior colliculus Brachium Superior colliculus Brachium Grey matter Pretectal area White : Sensory / ascending Spinotectal tract Central tegmental tract White : Motor / descending Tectospinal tract Peduncle ( Ventral ) Tegmentum White : Sensory / ascending Lemnisci Medial Lateral Ascending MLF Vestibulo - oculomotor fibers Spinothalamic tract Anterior trigeminothalamic tract Dentatothalamic tract White : Motor / descending Rubrospinal tract Rubro - olivary tract Descending MLF Grey : cranial nuclei GSA Mesencephalic - GSE Oculomotor nucleus, Trochlear nucleus - GVE Edinger -- Westphal nucleus Grey : other Periaqueductal gray Raphe nuclei dorsal Ventral tegmental area Rostromedial tegmental nucleus Pedunculopontine nucleus Red nucleus Rostral interstitial nucleus of medial longitudinal fasciculus Parabrachial area Interpeduncular nucleus Midbrain reticular formation Ventricular system Cerebral aqueduct Base White : Motor / descending Cerebral crus : Corticospinal tract Corticobulbar tract Corticopontine tract / Frontopontine fibers / Temporopontine fibers Grey : Substantia nigra Pars compacta Pars reticulata Surface Superior cerebellar peduncle Decussation Interpeduncular fossa GND : 4072520 - 0 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Brainstem&oldid=861141795 '' Categories : Brainstem Neurophysiology Hidden categories : CS1 maint : Archived copy as title Articles needing additional references from January 2013 All articles needing additional references Articles to be expanded from April 2014 All articles to be expanded Articles using small message boxes All articles with unsourced statements Articles with unsourced statements from September 2017 Articles to be expanded from October 2016 Wikipedia articles with GND identifiers Talk Contents About Wikipedia Български Bosanski Brezhoneg Català Čeština Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 Bahasa Indonesia Italiano עברית Basa Jawa Қазақша Kreyòl ayisyen Latviešu Lietuvių Magyar Bahasa Melayu Nederlands 日本 語 Norsk Norsk nynorsk Polski Português Română Русский Simple English Slovenčina Slovenščina کوردی Suomi Svenska தமிழ் ไทย Türkçe Українська ئۇيغۇرچە / Uyghurche Tiếng Việt 粵語 中文 41 more Edit links This page was last edited on 25 September 2018, at 11 : 45 ( UTC ). 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Question: which structure of the brain stem is primarily related to alertness
Answer: Reticular formation