Neuroanatomy - Corticospinal Tract (USMLE) скачать в хорошем качестве

Neuroanatomy - Corticospinal Tract (USMLE)

Neuroanatomy of the descending Corticospinal Tract for the USMLE. Including the pyramidal tracts CORTICOSPINAL TRACT Primarily deals with fine skilled movements. It can also help in skill and agility, very precise movements. First draw the lobes of the brain, the midbrain, pons and medulla oblangata and finally the spinal cord. It begins with the pyramidal cells in particular the 5th layers of the cerebral cortex. One third comes from primary motor cortex, one third from the secondary cortex, and one third from post-central gyrus. Legs are found in the middle and face is found more laterally. The thalamus is one both sides of the 4th ventricle. All the fibers converge on the posterior limb of the internal capsule which forms the corona radiata that converges on the posterior limb of the internal capsule. From there is goes to the midbrain. IN the back there are two superior colliculi the cerebral aquedact and substantia nigra. It is divided into the tectum, tegmuntum and crus cereberi. They pass through the middle three-fifths of the crus cereberi, which is also konwn as the basis pedunculis of midbrain. The pons have lots of gray matter and many fibers going through to the cerebellum. These fibers are known as pontocerebellar fibers. In order for the cerebrospinal tract to go through it must split up. It goes to the medulla, in particular the pyramids. Afterwards 90% of them will cross to the contrlateral side. 10% stay uncrossed. The 90% that cross form the lateral corticospinal tract and the 10% that do not cross form the anterior corticospinal tract. The motor neurons leave from the anterior horns as they arise as the secondary neurons. The anterior corticospinal tract crosses at the spinal level. There is some branching that occurs. Initially it branches to adjacent cells and inhibits nearby cells. Second branch to the basal ganglia. In the midbrain is the red nucleus for background cells. The reticular formation also receives fibers which maintains alertness while you are moving. The vestibular nucleus also recieves fibers for balance. The olivary nucleus sends information to the cerebellum about what you are trying to do.