What is included in the midbrain?
Midbrain, also called mesencephalon, region of the developing vertebrate brain that is composed of the tectum and tegmentum. The midbrain serves important functions in motor movement, particularly movements of the eye, and in auditory and visual processing.
The midbrain serves many roles, including motor function. Damage to the midbrain can result in a wide variety of movement disorders, difficulty with vision and hearing, and trouble with memory. Because the midbrain houses the hypothalamus, it also plays a major role in automatic body functions.
- The brain stem controls the flow of messages between the brain and the rest of the body, and it also controls basic body functions such as breathing, swallowing, heart rate, blood pressure, consciousness, and whether one is awake or sleepy. The brain stem consists of the midbrain, pons, and medulla oblongata.
- Caudally (posteriorly) the mesencephalon adjoins the pons (metencephalon), and rostrally it adjoins the diencephalon (eg., thalamus, hypothalamus). The midbrain is located below the cerebral cortex and above the hindbrain placing it near the center of the brain.
- Another nucleus of the basal ganglia is the substantia nigra ("black substance"). Located in the upper portions of the midbrain, below the thalamus, it gets its color from neuromelanin, a close relative of the skin pigment. One part (the pars compacta) uses dopamine neurons to send signals up to the striatum.
Structure. The midbrain comprises the tectum, tegmentum, the cerebral aqueduct, and the cerebral peduncles, as well as several nuclei and fasciculi. Caudally the midbrain adjoins the metencephalon (afterbrain) (pons and cerebellum). Rostrally it adjoins the diencephalon (thalamus, hypothalamus, etc.).
- The midbrain (see Fig. 2-17), located immediately below the thalamus and hypothalamus, is also called the mesencephalon. The midbrain is the narrowest part of the brainstem and contains the tectum, or roof, one of the three longitudinal divisions of the brainstem.
- Hindbrain, also called rhombencephalon, region of the developing vertebrate brain that is composed of the medulla oblongata, the pons, and the cerebellum.
- The cerebrum is divided into four regions called lobes that control senses, thoughts, and movements. The four lobes are the occipital, temporal, frontal, and parietal lobes. Although each lobe has a different task to perform, they all must work together.
(The midbrain and hindbrain are similar with other animals, hence the term Brain Stem.) The forebrain is composed of the limbic system, the thalamus, the hypothalamus, the basal ganglia, and the cerebral cortex. The limbic system is made up of the amygdala and the hippocampus.
- The cerebral cortex (the largest part of the brain) is responsible for higher thought processes. The two symmetrical hemispheres of the cerebrum are divided into four lobes (frontal, parietal, occipital and temporal), with each lobe being responsible for various functions.
- The cerebellum (back of brain) is located at the back of the head. Its function is to coordinate voluntary muscle movements and to maintain posture, balance, and equilibrium.
- The pons contains nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.
Updated: 21st October 2019