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Mesencephalon
The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum. It is functionally associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation.Breedlove, Watson, & Rosenzweig. Biological Psychology, 6th Edition, 2010, pp. 45-46 The name ''mesencephalon'' comes from the Greek ''mesos'', "middle", and ''enkephalos'', "brain". Structure The midbrain is the shortest segment of the brainstem, measuring less than 2cm in length. It is situated mostly in the posterior cranial fossa, with its superior part extending above the tentorial notch. The principal regions of the midbrain are the tectum, the cerebral aqueduct, tegmentum, and the cerebral peduncles. Rostral and caudal, Rostrally the midbrain adjoins the diencephalon (thalamus, hypothalamus, etc.), while Rostral and caudal, cau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diencephalon
In the human brain, the diencephalon (or interbrain) is a division of the forebrain (embryonic ''prosencephalon''). It is situated between the telencephalon and the midbrain (embryonic ''mesencephalon''). 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 diencephalon is one of the main brain vesicle, vesicles of the brain formed during human embryonic development, embryonic development. During the third week of development a neural tube is created from the ectoderm, one of the three primary germ layers, and forms three main vesicles: the prosencephalon, the Midbrain, mesencephalon and the Hindbrain, rhombencephalon. The prosencephalon gradually divides into the telencephalon (the cerebrum) and the diencephalon. Structure The diencephalon consists of the following structures: * Thalamus * Hypothalamus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebral Aqueduct
The cerebral aqueduct (aqueduct of the midbrain, aqueduct of Sylvius, Sylvian aqueduct, mesencephalic duct) is a small, narrow tube connecting the third and fourth ventricles of the brain. The cerebral aqueduct is a midline structure that passes through the midbrain. It extends rostrocaudally through the entirety of the more posterior part of the midbrain. It is surrounded by the periaqueductal gray (central gray), a layer of gray matter. Congenital stenosis of the cerebral aqueduct is a cause of congenital hydrocephalus. It is named for Franciscus Sylvius. Anatomy The cerebral aqueduct is roughly circular in transverse section, and measures 1-2 mm in diameter. It is 15 mm long and is commonly subdivided into a pars anterior antrum, and pars posterior. Relations Rostrally, it is continuous with the third ventricle, commencing just inferior to the posterior commissure. Caudally, it is continuous with the fourth ventricle at the junction of the mesencephalon and pons. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tegmentum
The tegmentum (from Latin for "covering") is a general area within the brainstem. The tegmentum is the ventral part of the midbrain and the tectum is the dorsal part of the midbrain. It is located between the ventricular system and distinctive basal or ventral structures at each level. It forms the floor of the midbrain (mesencephalon) whereas the tectum forms the ceiling. It is a multisynaptic network of neurons that is involved in many subconscious homeostatic and reflexive pathways. It is a motor center that relays inhibitory signals to the thalamus and basal nuclei preventing unwanted body movement. The tegmentum area includes various different structures, such as the rostral end of the reticular formation, several nuclei controlling eye movements, the periaqueductal gray matter, the red nucleus, the substantia nigra, and the ventral tegmental area. The tegmentum is the location of several cranial nerve nuclei. The nuclei of CN III and IV are located in the tegmentum port ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brainstem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum 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, and sometimes the diencephalon is included in the brainstem. The brainstem is very small, making up around only 2.6 percent of the brain's total weight. It has the critical roles of regulating heart and respiratory system, respiratory function, helping to control heart rate and breathing rate. It also provides the main motor and sensory nerve supply to the face and neck via the cranial nerves. Ten pairs of cranial nerves come from the brainstem. Other roles include the regulation of the central nervous system and the body's sleep cycle. It is also of prime importance in the conveyance of motor and sensory pathways from the rest of the brain to the body, and from the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Colliculus
In neuroanatomy, the superior colliculus () is a structure lying on the tectum, roof of the mammalian midbrain. In non-mammalian vertebrates, the Homology (biology), homologous structure is known as the optic tectum or optic lobe. The adjective form ''tectum, tectal'' is commonly used for both structures. In mammals, the superior colliculus forms a major component of the midbrain. It is a paired structure and together with the paired inferior colliculi forms the corpora quadrigemina. The superior colliculus is a layered structure, with a pattern that is similar in all mammals. The layers can be grouped into the superficial layers (retinal nerve fiber layer, stratum opticum and above) and the deeper remaining layers. Neurons in the superficial layers receive direct input from the retina and respond almost exclusively to visual stimuli. Many neurons in the deeper layers also respond to other modalities, and some respond to stimuli in multiple modalities. The deeper layers also conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inferior Colliculus
The inferior colliculus (IC) (Latin for ''lower hill'') is the principal midbrain nucleus of the Auditory system, auditory pathway and receives input from several peripheral brainstem nuclei in the auditory pathway, as well as inputs from the auditory cortex.Shore, S. E.: ''Auditory/Somatosensory Interactions''. In: Squire (Ed.): ''Encyclopedia of Neuroscience'', Academic Press, 2009, pp. 691–695 The inferior colliculus has three subdivisions: the central nucleus, a dorsal cortex by which it is surrounded, and an external cortex which is located laterally. Its bimodal neurons are implicated in auditory-Somatosensory system, somatosensory interaction, receiving projections from Somatosensory system, somatosensory nuclei. This multisensory integration may underlie a filtering of self-effected sounds from vocalization, chewing, or respiration activities. The inferior colliculi together with the superior colliculi form the eminences of the corpora quadrigemina, and also part of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebrum
The cerebrum (: cerebra), telencephalon or endbrain is the largest part of the brain, containing the cerebral cortex (of the two cerebral hemispheres) as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In the human brain, the cerebrum is the uppermost region of the central nervous system. The cerebrum prenatal development, develops prenatally from the forebrain (prosencephalon). In mammals, the Dorsum (biology), dorsal telencephalon, or Pallium (neuroanatomy), pallium, develops into the cerebral cortex, and the ventral telencephalon, or Pallium (neuroanatomy), subpallium, becomes the basal ganglia. The cerebrum is also divided into approximately symmetric Lateralization of brain function, left and right cerebral hemispheres. With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the human body. Structure The cerebrum is the largest part of the brain. Depending upon the position of the animal, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Cranial Fossa
The posterior cranial fossa is the part of the cranial cavity located between the foramen magnum, and tentorium cerebelli. It is formed by the sphenoid bones, temporal bones, and occipital bone. It lodges the cerebellum, and parts of the brainstem. Anatomy The posterior cranial fossa is formed by the sphenoid bones, temporal bones, and occipital bone. It is the most inferior of the fossae. It houses the cerebellum, medulla oblongata, and pons. Boundaries Anteriorly, the posterior cranial fossa is bounded by the dorsum sellae, posterior aspect of the body of sphenoid bone, and the basilar part of occipital bone/ clivus. Laterally, it is bounded by the petrous parts and mastoid parts of the temporal bones, and the lateral parts of occipital bone. Posteriorly, it is bounded by the squamous part of occipital bone. Features Foramen magnum The foramen magnum is a large opening of the floor of the posterior cranial fossa, its most conspicuous feature. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mosby's Medical, Nursing & Allied Health Dictionary
''Mosby's Dictionary of Medicine, Nursing & Health Professions'' is a dictionary of health-related topics. The 11th edition, published in 2021, contains 2,080 pages and 2,450 illustrations. It includes some encyclopaedic definitions and 12 appendixes containing reference information. Earlier versions are titled ''Mosby's Medical, Nursing & Allied Health Dictionary''. In 2024, it was designated an "Essential Purchase" for small medical libraries by Doody’s Core Titles. References Medical dictionaries {{med-book-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tentorial Notch
The tentorial notch (also known as the tentorial incisure or incisura tentorii) refers to the anterior opening between the free edge of the cerebellar tentorium and the clivus for the passage of the brainstem. The midbrain continues with the thalamus of the diencephalon through the tentorial notch. Structure The tentorial notch is located between the tentorial edges and communicates the supratentorial and infratentorial spaces. This area can be divided into three spaces: ''anterior'', ''middle'' (lateral to), and ''posterior'' to the brainstem. The middle incisural space is close to the midbrain and the upper pons at the level of the pontomesencephalic sulcus. Medial temporal lobe structures such as the uncus, the parahippocampal gyrus and the hippocampal formation, are also intimately related to the incisura. The principal vascular structures coursing along the middle incisural space are the posterior cerebral artery and the superior cerebellar artery which pass around the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
