The midbrain or mesencephalon, there is a part of the brainstem connecting the upper brain and forebrains. Many nerves run through the midbrains that connect the brain to the cerebellum and other posterior brain structures. The midbrain function is to support the movement, as well as visual and auditory processing. Damage to some areas of the midbrain is associated with the development of Parkinson’s disease.
The midbrain function includes:
Controlling the view response
Regulate muscle movement
midbrain function is the most rostral part of the brainstem. It is located between the forebrain and hindbrain.
Many structures are located in the midbrain including the tegmentum, cerebral stalk, black matter, crus cerebri and cranial nerves (holomorphic and pale-faced). Tectum consists of rounded convexities called colliculi, which are involved in visual and hearing processes.
The cerebral skeleton is a bundle of nerve fibers that connect the forebrains and hindbrain. The cerebral skeleton contains tegmentum (forms the basis of the midbrain) and crus cerebri (nerve lines that connect the brain with the cerebellum). The substantia nigra has neural connections to the frontal lobes and other areas of the brain involved in the midbrain function. Cells in the substantia nigra also produce dopamine, a chemical messenger that helps to coordinate muscle movements.
Neurodegeneration of nerve cells in the substantia nigra reduces dopamine production. Significant loss of dopamine levels (60-80%) can cause the development of Parkinson’s disease. Parkinson’s disease is a disorder of the nervous system that causes loss of control and motor coordination. Symptoms include tremors, slowness of movement, muscle stiffness, and balance problems.
The midbrains form three main structures: the cerebral stalk (pedicel denoting the “foot” or “base” of the brain), the corpora Quadri Gemina (which means “all fours” because it has four mounds or hill-like structures), and the cerebral aqueduct, which is the dividing canal both structures. Now that we know the structures, let us take a moment to look at them individually so that we can better understand their unique roles.
The main function of the cerebral stalk is the transmission of motor signals from the brain to the brainstem. It consists of a thick bundle of nerve fibers, called corticospinal tracts, that carry motor signals from the brain to the muscles. Do not be fooled; the cerebral stalk is not just a “truck driver”, carrying its “load” of motor signals from one place to another; it also communicates with the cerebellum and thus helps to fine tune motor motions.
It is important to remember that the cerebellum, not being part of the midbrain, communicates with the cerebral stalks through something called the red nucleus. Proprioception is a sense of your own body in the environment, which means that even with blindfolded eyes, you can feel things like your hands, and feet that are against each other or when you’re upside down or on the right.
This is a pretty cool feature and in its absence. We would be really helpless and completely devoid of grace in our environment. If the motor signals come straight from our brains, without going through the “cleansing” mid-brains, one would say goodbye to dance competitions, because we would all be really horrible!