This region primarily consists of nerve fibers that form conduction tracts between the higher brain centers and spinal cord. The pons is the bulging middle portion of the brain stem. The midbrain is the most superior portion of the brain stem. It consists of three parts: midbrain, pons, and medulla oblongata. The brain stem is the region between the diencephalons and the spinal cord. This small gland is involved with the onset of puberty and rhythmic cycles in the body. The epithalamus is the most dorsal portion of the diencephalons. The hypothalamus is a small region below the thalamus, which plays a key role in maintaining homeostasis because it regulates many visceral activities. The sense of smell, going to the cerebral cortex. The thalamus, about 80 percent of the diencephalons, consists of two oval masses of gray matter that serve as relay stations for sensory impulses, except for It includes the thalamus, hypothalamus, and epithalamus. The diencephalons is centrally located and is nearly surrounded by the cerebral hemispheres. A fifth lobe, the insula or Island of Reil, lies deep within the lateral sulcus. The two hemispheres are two separate entities but are connected by an arching band of white fibers, called the corpus callosum that provides a communication pathway between the two halves.Įach cerebral hemisphere is divided into five lobes, four of which have the same name as the bone over them: the fontal lobe, the parietal lobe, the occipital lobe, and the temporal lobe. The largest and most obvious portion of the brain is the cerebrum, which is divided by a deep longitudinal fissure into two cerebral hemispheres. The brain is divided into the cerebrum, diencephalons, brain stem, and cerebellum. Although meningiomas are usually not likely to spread, physicians often treat them as though they were malignant to treat symptoms that may develop when a tumor applies pressure to the brain. Meningiomas are tumors of the nerve tissue covering the brain and spinal cord. This thin, delicate membrane is tightly bound to the surface of the brain and spinal cord and cannot be dissected away without damaging the surface. The pia mater is the innermost layer of meninges. The space under the arachnoid, the subarachnoid space, is filled with cerebrospinal fluid and contains blood vessels. The middle layer of meninges is arachnoid, which resembles a cobweb in appearance, is a thin layer with numerous threadlike strands that attach it to the innermost layer. The outer layer, the dura mater, is tough white fibrous connective tissue. There are three layers of meninges around the brain and spinal cord. In addition to bone, the CNS is surrounded by connective tissue membranes, called meninges, and by cerebrospinal fluid. The brain is continuous with the spinal cord at the foramen magnum. The brain is surrounded by the cranium, and the spinal cord is protected by the vertebrae. The CNS consists of the brain and spinal cord, which are located in the dorsal body cavity. The following activity addresses the nuclei, tracts, and functions of the brainstem.Ĭopyright © 2023, StatPearls Publishing LLC.Acknowledgements The Central Nervous System Clinicians can localize lesions of the brainstem with a thorough knowledge of brainstem anatomy and functions. Ten of the twelve cranial nerves arise from their cranial nerve nuclei in the brainstem. These tracts travel both to the brain (afferent) and from the brain (efferent), such as the somatosensory pathways and the corticospinal tracts, respectively. Some of the white matter tract cell bodies are located within the brainstem as well. The white matter tracts of the brainstem include axons of nerves traversing their course to different structures the axons originate from cell bodies located elsewhere within the central nervous system (CNS). The grey matter within the brainstem consists of nerve cell bodies and forms many important brainstem nuclei. The brainstem contains many critical collections of white and grey matter. It is responsible for many vital functions of life, such as breathing, consciousness, blood pressure, heart rate, and sleep. It is composed of three sections in descending order: the midbrain, pons, and medulla oblongata. The brainstem is the structure that connects the cerebrum of the brain to the spinal cord and cerebellum.
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