Myelencephalon

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Myelencephalon
Afterbrain
EmbryonicBrain.svg
Diagram depicting the main subdivisions of the embryonic vertebrate brain. These regions will later differentiate into forebrain, midbrain and hindbrain structures
Details
Identifiers
Latin myelencephalon
MeSH D054024
NeuroNames 698
TA98 A14.1.03.003
TA2 5983
Anatomical terms of neuroanatomy

The myelencephalon or afterbrain[ citation needed ] is the most posterior region of the embryonic hindbrain, from which the medulla oblongata develops. [1]

Contents

Myelencephalon is from myel- (bone marrow or spinal cord) and encephalon (the vertebrate brain). [2] [3] [4]

Development

Neural tube to myelencephalon

During fetal development, divisions of the neural tube that give rise to the hindbrain (rhombencephalon) and the other primary vesicles (forebrain and midbrain) occur at 28 days after conception. With the exception of the midbrain, these primary vesicles undergo further differentiation at 5 weeks after conception to form the myelencephalon and the other secondary vesicles. [5]

Myelencephalon to medulla

Final shape differentiation of the myelencephalon into the medulla oblongata can be observed at 20 weeks gestation. [5]

Neural TubePrimary VesiclesSecondary VesiclesAdult Structures
Brain Forebrain TelencephalonRhinencephalon, Amygdala, Hippocampus, Cerebrum(Cortex), Basal Ganglia,Lateral ventricles
Diencephalon Epithalamus, Thalamus, Hypothalamus, Subthalamus, Pituitary, Pineal, Third ventricle
Midbrain MesencephalonTectum, Cerebral peduncle, Pretectum, Cerebral aqueduct
Hindbrain MetencephalonPons, Cerebellum
MyelencephalonMedulla Oblongata
Spinal cord

[6]

Primary and secondary vesicle stages of development 1302 Brain Vesicle DevN.jpg
Primary and secondary vesicle stages of development

Medulla oblongata

The medulla oblongata is part of the brain stem that serves as the connection of the spinal cord to the brain. It is situated between the pons and the spinal cord.

Medulla oblongata- animation Medulla oblongata small.gif
Medulla oblongata- animation

Function

The medulla oblongata is responsible for several functions of the autonomic nervous system. These functions include: [8]

1) Respiration: monitors the acidity of the blood and sends electrical signals to intercostal muscle tissue to increase their contraction rate in order to oxygenate the blood as needed.

2) Cardiac & Vasomotor Center: [9] monitors and regulates cardiovascular activities by:

3) Reflexes

Damage/trauma

Because of its location in the brainstem and its many important roles in the autonomic nervous system, damage to the medulla oblongata is usually fatal.

Related Research Articles

<span class="mw-page-title-main">Brain</span> Organ central to the nervous system

The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for special senses such as vision, hearing and olfaction. Being the most specialized organ, it is responsible for receiving information from the sensory nervous system, processing those information and the coordination of motor control.

<span class="mw-page-title-main">Central nervous system</span> Brain and spinal cord

The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts. It is a structure composed of nervous tissue positioned along the rostral to caudal axis of the body and may have an enlarged section at the rostral end which is a brain. Only arthropods, cephalopods and vertebrates have a true brain, though precursor structures exist in onychophorans, gastropods and lancelets.

<span class="mw-page-title-main">Autonomic nervous system</span> Division of the nervous system supplying internal organs, smooth muscle and glands

The autonomic nervous system (ANS), sometimes called the visceral nervous system and formerly the vegetative nervous system, is a division of the nervous system that operates internal organs, smooth muscle and glands. The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, its force of contraction, digestion, respiratory rate, pupillary response, urination, and sexual arousal. This system is the primary mechanism in control of the fight-or-flight response.

<span class="mw-page-title-main">Sympathetic nervous system</span> Part of the autonomic nervous system which stimulates fight-or-flight responses

The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.

<span class="mw-page-title-main">Medulla oblongata</span> Structure of the brain stem

The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions, ranging from vomiting to sneezing. 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. "Medulla" is from Latin, ‘pith or marrow’. And "oblongata" is from Latin, ‘lengthened or longish or elongated'.

<span class="mw-page-title-main">Neural tube</span> Developmental precursor to the central nervous system

In the developing chordate, the neural tube is the embryonic precursor to the central nervous system, which is made up of the brain and spinal cord. The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into the closed neural tube. In humans, neural tube closure usually occurs by the fourth week of pregnancy.

<span class="mw-page-title-main">Brainstem</span> Posterior part of the brain, adjoining and structurally continuous

The brainstem is the stalk-like part of the brain that connects the forebrain with the spinal cord. In the human brain, the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch.

<span class="mw-page-title-main">Ventricular system</span> Structures containing cerebrospinal fluid

In neuroanatomy, the ventricular system is a set of four interconnected cavities known as cerebral ventricles in the brain. Within each ventricle is a region of choroid plexus which produces the circulating cerebrospinal fluid (CSF). The ventricular system is continuous with the central canal of the spinal cord from the fourth ventricle, allowing for the flow of CSF to circulate.

<span class="mw-page-title-main">Extrapyramidal system</span> Connection between brain and spinal cord

In anatomy, the extrapyramidal system is a part of the motor system network causing involuntary actions. The system is called extrapyramidal to distinguish it from the tracts of the motor cortex that reach their targets by traveling through the pyramids of the medulla. The pyramidal tracts may directly innervate motor neurons of the spinal cord or brainstem, whereas the extrapyramidal system centers on the modulation and regulation of anterior (ventral) horn cells.

<span class="mw-page-title-main">Diencephalon</span> Division of the forebrain around the third ventricle

In the human brain, the diencephalon is a division of the forebrain. It is situated between the telencephalon and the midbrain. The diencephalon has also been known as the tweenbrain in older literature. It consists of structures that are on either side of the third ventricle, including the thalamus, the hypothalamus, the epithalamus and the subthalamus.

The cardiovascular centre is a part of the human brain which regulates heart rate through the nervous and endocrine systems. It is considered one of the vital centres of the medulla oblongata.

<span class="mw-page-title-main">Hindbrain</span> Part of the embryonic brain

The hindbrain, rhombencephalon or lower brain is a developmental categorization of portions of the central nervous system in vertebrates. It includes the medulla, pons, and cerebellum. Together they support vital bodily processes.

<span class="mw-page-title-main">Metencephalon</span> Part of the embryonic brain

The metencephalon is the embryonic part of the hindbrain that differentiates into the pons and the cerebellum. It contains a portion of the fourth ventricle and the trigeminal nerve, abducens nerve, facial nerve, and a portion of the vestibulocochlear nerve.

<span class="mw-page-title-main">Neural groove</span> Shallow median groove of the neural plate between the neural folds of an embryo

The neural groove is a shallow median groove of the neural plate between the neural folds of an embryo. The neural plate is a thick sheet of ectoderm surrounded on either side by the neural folds, two longitudinal ridges in front of the primitive streak of the developing embryo.

<span class="mw-page-title-main">Lateral grey column</span>

The lateral grey column is one of the three grey columns of the spinal cord ; the others being the anterior and posterior grey columns. The lateral grey column is primarily involved with activity in the sympathetic division of the autonomic motor system. It projects to the side as a triangular field in the thoracic and upper lumbar regions of the postero-lateral part of the anterior grey column.

<span class="mw-page-title-main">Neuroectoderm</span> Ectoderm that goes on to form the neural plate

Neuroectoderm consists of cells derived from the ectoderm. Formation of the neuroectoderm is the first step in the development of the nervous system. The neuroectoderm receives bone morphogenetic protein-inhibiting signals from proteins such as noggin, which leads to the development of the nervous system from this tissue. Histologically, these cells are classified as pseudostratified columnar cells.

Neurocardiology is the study of the neurophysiological, neurological and neuroanatomical aspects of cardiology, including especially the neurological origins of cardiac disorders. The effects of stress on the heart are studied in terms of the heart's interactions with both the peripheral nervous system and the central nervous system.

<span class="mw-page-title-main">Brain vesicle</span>

Brain vesicles are the bulge-like enlargements of the early development of the neural tube in vertebrates, which eventually give rise to the brain.

<span class="mw-page-title-main">Flexure (embryology)</span> Part of the embryonic neural tube

Three flexures form in the part of the embryonic neural tube that develops into the brain. At four weeks gestational age in the human embryo, the neural tube has developed at the cranial end into three swellings – the primary brain vesicles. The space into which the cranial part of the neural tube is developing is limited. This limitation causes the neural tube to bend, or flex, at two ventral flexures – the rostral cephalic flexure, and the caudal cervical flexure. It also bends dorsally into the pontine flexure. These flexures have formed by the time that the primary brain vesicles have developed into five secondary brain vesicles in the fifth week.

References

  1. "Myelencephalon". Segen's Medical Dictionary. 2011. Retrieved 2015-05-05.
  2. https://www.merriam-webster.com/dictionary/myelencephalon [ bare URL ]
  3. https://www.merriam-webster.com/dictionary/myelo- [ bare URL ]
  4. https://www.merriam-webster.com/dictionary/encephalon [ bare URL ]
  5. 1 2 Carlson, Neil R. Foundations of Behavioral Neuroscience.63-65
  6. "Neural - Myelencephalon Development - Embryology". embryology.med.unsw.edu.au. Retrieved 2015-05-05.
  7. "OpenStax CNX". cnx.org. Retrieved 2015-05-05.
  8. Loewy, A. D., & Spyer, K. M. (Eds.). (1990). Central regulation of autonomic functions. Oxford University Press, USA.145-164
  9. "Cardiovascular Regulation" (PDF). www.colorado.edu. Archived from the original (PDF) on 2017-08-30. Retrieved 2015-05-05.