In addition, the reticular formation contains neuronal circuits responsible for regulation of respiration, for cardiovascular responses to blood pressure and oxygen level modulations, as well as for coordination of swallowing and other oromotor functions. Thus the cerebral cortex requires input from the brainstem to maintain awareness and arousal. Damage to these ascending brainstem fibers, collectively called the ascending reticular activating system, results in loss of consciousness and coma, even in the absence of any damage to the cerebral hemispheres. A subset of the reticular formation neurons sends fibers to the intralaminar thalamic nuclei, which in turn project widely throughout the cerebral cortex. It plays a fundamental role in arousal and consciousness, control of movement and sensation, and in regulation of visceral functions. The brainstem reticular formation is not a separate anatomic structure but is instead distributed throughout the core of the brainstem from the medulla into the midbrain. Clark, in Pediatric Critical Care (Fourth Edition), 2011 Reticular Formation Overall, the brainstem performs highly critical functions for maintaining proper bodily function and survival. It regulates the processes of sleeping and dreaming as it is the location in the brain where rapid eye movement (REM) sleep associated with dreaming occurs. It relays messages between the cerebrum and the cerebellum to ensure proper brain activity. While the pons region of the brainstem is relatively small, its function is critical in several ways. Injuries to this specific region of the brainstem are often critical and life threatening as mentioned previously, an inability to breathe can lead to death. Thus, it is critical to have a functioning medulla oblongata for survival. It also controls the autonomic activity of the heart and lungs, including involuntary activity. Accordingly, it forms the lowest region of the brainstem. The medulla oblongata, a cone-shaped region of the brainstem, serves as the continuation of the spinal cord into the skull. These nerves are known as cranial nerves because they exit the skull. The nerves responsible for sensing and movement in the face branch out from the brainstem, enabling us to respond to stimuli. In addition to controlling these major bodily functions, the major nerve conduction pathways (often referred to as tracts) that regulate our ability to sense start in the brain, then move through the brainstem and into the spinal cord before branching out all over the body. Injuries to the brainstem can be life threatening, as they can result in an inability to breathe involuntary, which often will lead to death. Additionally, it plays an important role in controlling consciousness and the process of sleeping. The brainstem regulates and maintains the cardiac and respiratory systems. This structure plays several significant roles in maintaining proper function of the nervous system and its control over our bodies. The brainstem serves as the physical structure that connects the brain to the spinal cord, containing portions of the mid and hindbrain regions. Stephanie Willerth, in Engineering Neural Tissue from Stem Cells, 2017 2.1.3 Brainstem The vagus provides a parasympathetic supply to thoracic and abdominal viscera, the latter supplemented by the sacral parasympathetic. Visceral components of cranial nerves are represented in the medulla by vagal and glossopharyngeal nuclei. Other fibers emerge dorsally from the lateral surface of the cord to form the spinal accessory (XI) nerve, ascending through the foramen magnum to supply branchial arch musculature. The ventral nerve roots supply myotomal muscles. Motor nerve roots emerge from the upper cervical cord in two separate rows for the muscles of dissimilar developmental origin. The spinal pattern of grey matter is altered in the medulla. Two tracts in the spinal ventral funiculus are displaced dorsally in the medulla by the pyramid and medial lemniscus these are the tectospinal tract and the medial longitudinal fasciculus. On each side of the medulla, corticospinal fibers are located ventrally in the pyramids. The study of the brainstem helps to examine the way grey and white matter of the cervical spinal cord are rearranged in the medulla. Wilkinson OBE, MD, FRCS, in Neuroanatomy for Medical Students (Second Edition), 1992 Publisher Summary
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