Midbrain

Midbrain Anatomy

This picture is a very common transverse section A cut or slice of the body or an organ for study. of the midbrainThe upper portion of the brainstem involved in visual and auditory processing.. This little star shaped or + shaped hole is the cerebral aqueduct. This is that very very small canal connecting the 3rd and 4th ventricles. Sometimes in growing children, this very narrow cerebral aqueduct becomes pinched. This restricts the flow of CSF from the choroid plexuses to the spinal cordThe central nervous system structure that relays signals between the brain and body..  In this case, CSF will build up in the brain.  A neural shunt is an artificial support that can hold open the cerebral aqueduct.  These shunts are similar to the stents used to hold open arteriesBlood vessels that carry oxygenated blood away from the heart (except pulmonary arteries, which carr.

Superior and Inferior Colliculi

These two bulges come off the dorsalRelating to the back side of the body. side of the midbrain. They are only two of the four bulges. These are called the colliculi. The top 2 bulges are the superiorAbove or toward the upper part of the body. colliculus and the bottom 2 as the inferiorBelow or toward the lower part of the body. colliculus.

The superior colliculus Is involved in tracking eye movements and objects in relation to your position. It coordinates reflexive headRounded proximal end that fits into the acetabulum of the hip bone. movements in response to what you see.  These superior colliculi are hardwired to the optic nerve, cranial nerve II and receive tons of visual information to process.. The inferior colliculus consolidates auditory input to determine where a sound was made in relationship to your position.

Sports like baseball and past-times like listening to music can stimulate these areas in a growing child.  This is why sports such as T-ball and soccer can help develop these areas. 

Midbrain’s Motor Control

The red nucleusA midbrain structure involved in motor coordination. is grey matter kind of on either side of the crotch of the midbrain here. The red nucleusThe control center of the cell that contains DNA and directs cellular activities. is highly involved with fine motor control of the hands. The red nucleus collaborates with the cerebellumThe brain region responsible for balance, coordination, and fine motor control. but also with the basal nucleiClusters of neurons in the brain that help regulate movement and coordination..

The substantia nigraA midbrain structure involved in movement and dopamine production. are these swaths of black that you see on this picture. The substantia nigra’s function is to make dopamineA catecholamine neurotransmitter involved in motor control, motivation, and reward.. When it makes dopamine though it produces melaninA brown-black pigment made by melanocytes in the stratum basal and given to keratinocytes as melanos as a byproduct. The substantial nigra on someone should be nice and dark with that neuromelanin. On the other side of the midbrain is an example. It shows how the substantia nigra looks in someone with Parkinson’s disease.

They would have a very lightly colored substantial nigra. This is because the root cause of Parkinson’s disease is the inability to make dopamine. Now when everything’s functioning correctly, dopamine made in your substantia nigra is used by the red nucleus. It is also used by your basal nucleiClusters of neurons in the CNS responsible for processing information. and your thalamusThe brain’s relay center, sending sensory information to the cerebral cortex. to inhibit unnecessary movements. One such unnecessary movementA fundamental property of life involving motion of the body or its parts. is a tremor. If you don’t have tremors, then your substantia nigra is likely making enough dopamine. This amount is sufficient for your basal nuclei and other parts of your brain to use. With Parkinson’s, the reduced ability to create dopamine for the basal nuclei causes a tremor. This tremor usually appears in the hands first because that’s where fine motor control exists.

Midbrain White/Gray Matter

There are two tabs coming off of the ventralRelating to the front or belly side of the body. side of the midbrain. There’s a lot of anatomyThe study of the structure of the human body. concerned with these tabs. In general, they are called the cerebral peduncles.  Cerebral peduncles should not be confused with cerebellar peduncles that came off the ponsA part of the brainstem that connects the cerebrum to the cerebellum and helps regulate breathing.. Cerebral peduncles physically support the big brain hat.  The peduncles are made up of myelinated axons of more than a few tractsBundles of nerve fibers in the CNS that carry signals between brain regions..

These are mostly myelinated axons that are the upper motor neuronsNeurons that originate in the brain and control lower motor neurons. of descending motor pathways. Axons of the corticospinal tractA descending motor pathway controlling voluntary movements. carry information from the primary motor cortex. They transmit it to the appropriate level of the spinal cord. Axons of the reticulospinal tract also facilitate this output. Those axons pass through these cerebral peduncles.