Brainstem Organization Flashcards
The brainstem extends from
the mamillary bodies to the pyramidal decussation
The pyramidal decussation marks
the decussation of the motor pathways
What are the ‘bumps’ of the dorsal membrane?
Superior and inferior colliculi
Along the floor of the 4th ventricle lie
facial colliculi formed by abducens nucleus and VII fibres
The medula conists of
dorsal columns and nuclei (gracile and cuneate tubercles)
What comprises the ventral aspect of the midbrain?
Cerebral peduncles
What are the cerebral peduncles made of?
White matter tracts coming down from the motor cortex
What comprises the ventral pons?
Cerebellar peduncles (white matter tracts attaching to the cerebellum)
What comprises the ventral medulla?
olives (more lateral) and pyramids (more medial)
What is the tectum?
Roof of the 3rd and 4th ventricles - comprises the dorsal aspect of the midbrain (superior and inferior colliculi)
What is the tegmentum?
Continuous with the spinal cord; lies between the cerebral aqueduct (dorsally) and the pons (ventrally)
The tegmentum contains
cranial nerve nuclei, nerve fibres connected to the cranial nerve nuclei including the reticular formation
What is the importance of the basilar region of the brainstem?
Descending motor control - corticospinal tracts; range of nuclei, some of which control these descending fibres via attachments to the cerebellum
General somatic nerves innervate
skeletal muscle and skin
General visceral nerves innerate
viscera - smooth muscle, glands, blood vessels
Spinal nerves end at
C2 (there is no C1 dermatome)
Which cranial nerves are exclusively motor?
III, IV, VI, XI, XII
Which cranial nerves are exclusively sensory?
I, II, VIII
Which cranial nerves are mixed?
V, VII, IX, X
Sensory nuclei develop from which plate?
Alar
Motor nuclei develop from which plate?
Basal
The general function of the reticular activating system is
regulating function of cranial nerves
The rostral reticular activating system is important in
controlling alertness and conscious state
The caudal reticular activating system is important in
regulation of survival reflexes, motor reflexes, autonomic functions, breathing, heart rate
How does the rostral reticular activating system function?
long projection systems ascending into the forebrain (cortex) defined by neurotransmitters
Noradrenergic ARAS projections start from which nucleus?
locus ceruleus
Dopaminergic ARAS projections start from
substantia nigra (important in movement)
Serotonergic ARAS projections originate from
dorsal raphae nucleus (important in mood and addiction)
The ventrolateral medullary reticular formation is responsible for
caudal - reflexes; regulates visceral functions of vagus X such as swallowing, vomiting, respiration (rhythm, coughing, hiccuping, sneezing), and cardiovascular responses
Locked-in syndrome generally affects
the ventral pons
The substantia nigra is found
in the ventral midbrain (basis)
The red nuclei are found
in the ventral midbrain (basis)
The cerebellar nuclei are found
in the ventral pons (basis)
