![]() ![]() The ventral tegmental area (VTA) is composed of paired cerebral peduncles. Several nuclei, tracts, and the reticular formation are contained here. The tegmentum which forms the floor of the midbrain, is ventral to the cerebral aqueduct. It is involved in the special sense of vision and sends its superior brachium to the lateral geniculate body of the diencephalon. The superior colliculus is positioned above the inferior colliculus, and marks the rostral midbrain. Its inferior brachium (arm-like process) reaches to the medial geniculate nucleus of the diencephalon. The inferior colliculus is the principal midbrain nucleus of the auditory pathway and receives input from several peripheral brainstem nuclei, as well as inputs from the auditory cortex. The tectum comprises the paired structure of the superior and inferior colliculi and is the dorsal covering of the cerebral aqueduct. The midbrain is further subdivided into three parts: tectum, tegmentum, and the ventral tegmental area. View of the midbrain showing covering tectum and tegmental floor Superior shown in green and inferior in orange. Main article: Midbrain Diagram showing the position of the colliculi. The brainstem extends from just above the tentorial notch superiorly to the first cervical vertebra below the foramen magnum inferiorly. The parts of the brainstem are the midbrain, the pons, and the medulla oblongata the diencephalon is sometimes considered part of the brainstem. These pathways include the corticospinal tract (motor function), the dorsal column-medial lemniscus pathway ( fine touch, vibration sensation, and proprioception), and the spinothalamic tract ( pain, temperature, itch, and crude touch). 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 body back to the brain. Other roles include the regulation of the central nervous system and the body's sleep cycle. Ten pairs of cranial nerves come from the brainstem. It also provides the main motor and sensory nerve supply to the face and neck via the cranial nerves. : 195 It has the critical roles of regulating cardiac, and respiratory function, helping to control heart rate and breathing rate. The brainstem is very small, making up around only 2.6 percent of the brain's total weight. : 152 The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The brainstem (or brain stem) is the stalk-like : 152 part of the brain that interconnects the cerebrum and diencephalon with the spinal cord. Therefore, they won't affect the diagnosis of brain death.A 3D medical animation still shot showing different parts of the midbrain. These spinal reflex movements are generated by the spinal cord and don't involve the brain at all. Occasionally, a person’s limbs or torso (the upper part of the body) may move, even after brain stem death has been diagnosed. The person is disconnected from the ventilator for a short period of time to see if they make any attempt to breathe on their own.īrain death will be diagnosed if a person fails to respond to all of these tests.A thin, plastic tube is placed down the trachea (windpipe) to see if it provokes gagging or coughing.Ice-cold water is inserted into each ear, which would usually cause the eyes to move.Pressure is applied to the forehead and the nose is pinched to see if there's any movement in response.The cornea (transparent outer layer of the eye), which is usually very sensitive, is stroked with a tissue or piece of cotton wool to see if the eye reacts.A torch is shone into both eyes to see if they react to the light.The tests used to determine whether brain stem death has occurred are outlined below: The tests are carried out twice to minimise any chance of error. Both doctors have to agree on the results for a diagnosis of brain death to be confirmed. The doctors will explain the tests to you and they'll keep you informed about your loved one's condition at all times. Neither of them can be involved with the hospital's transplant team. ![]() The diagnosis of brain death has to be made by two senior doctors. ![]() Once these factors have been ruled out, tests are carried out to confirm brain death. ![]()
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