03. The brainstem
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- Category: 2- Anatomy
- Published on 15 April 2012
- Written by Ben Brahim Mohammed
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The brainstem[ 32 , 38 ] is the brain anatomical structure that links different parts of the central nervous system: the forebrain, the cerebellum and the spinal cord.
The brainstem plays a vital role [ 32 , 41 , 46 ] in the many essential functions that its nuclei regulate [ 1 ], such as breathing and heart rate and even consciousness.
It is also a passageway to sensory and motor pathways, and a pain control center [ 47 , 48 ].
The brainstem represents the emergence area [ 41 ] of most cranial nerves [ 64 ].
We distinguish three parts of the brainstem [ 36 ] the midbrain [ 49 ], the pons [ 181 ] and the medulla oblongata [ 72 ].
1. Midbrain:
The midbrain "or mesencephalon" [ 38 ] is the area of the brainstem that is directly connected to the forebrain through the cerebral peduncles [ 38 ]. Behind these two peduncles, we find the tegmentum [ 49 , 50 , 51 ] with a hole in back side : the cerebral aqueduct. Also known as the aqueduct of Sylvius [ 41 , 43 , 72 ], it connects the 3rd to the 4th ventricle.
On the back of The midbrain is the tectum [ 39 ], with four colliculi (Also named corpora quadrigemina ) [ 226 ] where lie the reflex centers involving hearing and vision.
2. Pons:
The Pons "AKA the pons Varolii" [ 38 ] is the middle part of the brainstem.
It plays an important role in motor functions with its relay position between the forebrain and the cerebellum [ 52 ], it also contributes to autonomous functions and facial sensitivity (it containes the core and the emergence of the trigeminal nerve) [ 116 ]).
The Pons is connected to the cerebellum by the middle cerebellar peduncle [ 64 ]. It delimits the front face of the 4th ventricle [ 64 ].
3. Medulla oblongata:
The medulla oblongata [ 38 ] is the portion of the brainstem between the pons and the spinal cord [ 32 ]. The medulla contains the olivary and a pair of pyramids [ 119 ] that contain the corticospinal fibers of the pyramidal tract [ 39 ] of the pyramidal tract [ 179 , 227 ].
The medulla contains vital autonomic control centers for functions such as breathing, heart rate and Many reflex functions (vomiting, coughing, sneezing, and swallowing) [ 119 ].
It ends at the bottom by the pyramidal decussation [ 5 , 40 ]: a crossing region of the corticospinal fibers