The brainstem is the stalk-like part of the brain that interconnects the cerebrum and diencephalon 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.
The marginal nucleus of spinal cord, or posteromarginal nucleus, Rexed lamina I, is located at the most dorsal aspect of the dorsal horn of the spinal cord. The neurons located here receive input primarily from Lissauer's tract and relay information related to pain and temperature sensation. Pain sensation relayed here cannot be modulated, e.g. pain from burning the skin. The axons of neurons contribute to the lateral spinothalamic tract.
The fourth ventricle is one of the four connected fluid-filled cavities within the human brain. These cavities, known collectively as the ventricular system, consist of the left and right lateral ventricles, the third ventricle, and the fourth ventricle. The fourth ventricle extends from the cerebral aqueduct to the obex, and is filled with cerebrospinal fluid (CSF).
The longitudinal fissure is the deep groove that separates the two cerebral hemispheres of the vertebrate brain. Lying within it is a continuation of the dura mater called the falx cerebri. The inner surfaces of the two hemispheres are convoluted by gyri and sulci just as is the outer surface of the brain.
The epithalamus is a posterior (dorsal) segment of the diencephalon. The epithalamus includes the habenular nuclei, the stria medullaris, the anterior and posterior paraventricular nuclei, the posterior commissure, and the pineal gland.
The facial colliculus is an elevated area located in the pontine tegmentum, within the floor of the fourth ventricle. It is formed by fibres from the facial motor nucleus looping over the abducens nucleus. The facial colliculus is an essential landmark of the rhomboid fossa.
In the spinal cord, the most lateral of the bundles of the ventral nerve roots is generally taken as a dividing line that separates the antero-lateral region into two parts: an anterior funiculus , between the anterior median fissure and the most lateral of the ventral nerve roots; and a lateral funiculus, between the exit of these roots and the posterolateral sulcus.
The most lateral of the bundles of the anterior nerve roots is generally taken as a dividing line that separates the anterolateral system into two parts. These are the anterior funiculus, between the anterior median fissure and the most lateral of the anterior nerve roots, and the lateral funiculus between the exit of these roots and the posterolateral sulcus.
The posterior thoracic nucleus, is a group of interneurons found in the medial part of lamina VII, also known as the intermediate zone, of the spinal cord. It is located from the cervical segment C8 to lumbar segment L3 of the spinal cord and is an important structure for proprioception of the lower limb.
The area postrema, a paired structure in the medulla oblongata of the brainstem, is a circumventricular organ having permeable capillaries and sensory neurons that enable its dual role to detect circulating chemical messengers in the blood and transduce them into neural signals and networks. Its position adjacent to the bilateral nuclei of the solitary tract and role as a sensory transducer allow it to integrate blood-to-brain autonomic functions. Such roles of the area postrema include its detection of circulating hormones involved in vomiting, thirst, hunger, and blood pressure control.
The rhomboid fossa is a rhombus-shaped depression that is the anterior part of the fourth ventricle. Its anterior wall, formed by the back of the pons and the medulla oblongata, constitutes the floor of the fourth ventricle.
The lateral corticospinal tract is the largest part of the corticospinal tract. It extends throughout the entire length of the spinal cord, and on transverse section appears as an oval area in front of the posterior column and medial to the posterior spinocerebellar tract.
The olfactory peduncle is a bilateral bundle of afferent nerve fibers from the mitral and tufted cells of the olfactory bulb that connects to several target regions in the brain, including the piriform cortex, amygdala, and entorhinal cortex. It is a narrow white band, triangular on coronal section, the apex being directed upward.
A nerve fascicle is a bundle of nerve fibers belonging to a nerve in the peripheral nervous system. A nerve fascicle is also called a fasciculus, as is a nerve tract in the central nervous system.
The anterior vagal trunk is one of the two divisions into which the vagus nerve splits as it passes through the esophageal hiatus to enter the abdominal cavity. The anterior and posterior vagal trunks represent the inferior continuation of the esophageal nervous plexus inferior to the diaphragm. The majority of nerve fibres in the anterior vagal trunk are derived from the left vagus nerve.
The posterior vagal trunk is one of the two divisions into which the vagus nerve splits as it passes through the esophageal hiatus to enter the abdominal cavity. The anterior and posterior vagal trunks together represent the inferior continuation of the esophageal nervous plexus inferior to the diaphragm.
In the upper part of the medulla oblongata, the hypoglossal nucleus approaches the rhomboid fossa, where it lies close to the middle line, under an eminence named the hypoglossal trigone. It is a slight elevation in the floor of the inferior recess of the fourth ventricle, beneath which is the nucleus of origin of the twelfth cranial nerve.
The basilar part of pons, also known as basis pontis, is the ventral part of the pons; the dorsal part is known as the pontine tegmentum.
The medial vestibular nucleus is one of the vestibular nuclei. It is located in the medulla oblongata.
The habenular trigone is a small depressed triangular area situated anterior/superior to the superior colliculus. It contains the habenular nuclei.
