Brainstem Flashcards
Obex
apex of fourth ventricle where it narrows it the central canal opens to spinal cord (Medulla)
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Pyramidal decussation
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interrupts anterior median fissure, at junction of brainstem and spinal cord. Contains corticospinal tract, motor fibers form cerebral cortex on their way to the spinal cord. Note pyramid bounded by anterolateral sulcus. (anterior surface)
�Caudal Medulla
CN XII
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Hypoglossal nerve (cranial nerve XII) rootlet exit via anterolateral or preolivary sulcus �Rostral MEDULLA
Olive
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Bulge created by inferior olivary nucleus (MEDULLA)
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CN IX and CNX
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Rootlets of glossopharyngeal (IX) and vagus (X) nerves emerge from the post olivary sulcus, lateral to the olive.
�(MEDULLA)
cuneate tubercle
Fasciculus cuneatus extends to cuneate tubercle, marking site of the nucleus cuneatus. Fibers leave these nuclei and travel in an arch across the midline to form the medial lemniscus.
�(MEDULLA)
gracile tubercle
Fasciculus gracilus extends to the gracile tubercle which is at the site of nucleus gracilus. Fibers leave these nuclei and travel in an arch across the midline to form the medial lemniscus.
(Medulla)
Sulcus limitans
Sulcus limitans: Embryonic dividing line between sensory (now lateral) and motor (now medial) nuclei.
extends down spinal cord
sensory component swins out laterally during development
Hypoglossal trigone
triangular swelling in floor of 4th ventricle made by underlying hypoglossal nerve nucleus.
MEDULLA
Vagal trigone
triangular swelling in floor of 4th ventricle made by underlying dorsal motor nucleus of the vagus nerve. Vagus nerve is longest nerve
MEDULLA
Facial colliculus
Facial colliculus: Actually in pons, but since we are in the floor of the fourth ventricle now we can see it. This little hill is not due to the facial nerve motor nucleus, instead this is the site where the facial nerve loops over the abducens nerve nucleus as it goes on its way out of the brainstem.
Basal pons
Large bulge on anterior surface of brainstem. Site of many neurons that receive axons from cerebral cortex, the pontine neurons then send an axon across the midline of the pons (so-called crossing fibers) that collect laterally forming the middle cerebellar peduncle. )This is part of the cerebropontocerebellar pathway; more to come).
Middle cerebellar peduncle (MCP)
Major cerebellar input pathway. CAUDAL pons is attached to the cerebellum by the middle cerebellar peduncle
Trigeminal nerve (V):
Enters at midpontine level thru middle cerebellar peduncle.
lateral to pons but at midline
Abducens nerve (VI)
Exits brainstem at the pontomedullary junction near midline, near edge of pyramid as it emerges from the pons. Motor and sensory component.. Motor is rostral
Facial nerve (VII)
Exists lateral the abducens at the pontomedullary junction. Has two parts: motor root that is larger and more medial than the sensory root. Sometime the sensory root is known as the intermediate nerve. Cerebellar pontine angle