Brainstem Flashcards
Where is the brainstem located?
Between the cerebrum and spinal cord
What are the three components of the brainstem?
Midbrain
Pons
Medulla oblongata
What does the brainstem consist of in terms of grey/white matter?
Deep grey matter surrounded by white matter fibre tracts
What is the function of the brainstem?
Produces automatic behaviours necessary for survival e.g., breathing
Which embryonic structure does the midbrain develop from?
Mesencephalon
Which embryonic structure does the pons develop from?
Metencephalon
Which embryonic structure does the medulla oblongata develop from?
Myelencephalon
How many cranial nerves are there?
12 pairs
What is the first cranial nerve?
Olfactory
What is the second cranial nerve?
Optic
What is the third cranial nerve?
Occulomotor
What is the fourth cranial nerve?
Trochlear
What is the fifth cranial nerve?
Trigeminal
What is the sixth cranial nerve?
Abducens
What is the seventh cranial nerve?
Facial
What is the eighth cranial nerve?
Vestibulocochlear
What is the ninth cranial nerve?
Glossopharyngeal
What is the tenth cranial nerve?
Vagus
What is the eleventh cranial nerve?
Accessory
What is the twelfth cranial nerve?
Hypoglossal
Which cranial nerve is the only one to emerge from the posterior aspect of the brain stem?
Trochlear
Which cranial nerves are purely sensory?
CN1 - Olfactory
CN2 - Optic
CN8 - Vestibulocochlear
Which cranial nerves are purely motor?
CN3 - oculomotor
CN4 - trochlear
CN6 - abducens
CN11 - accessory
CN12 - hypoglossal
Which cranial nerves are both sensory and motor?
CN5 - trigeminal
CN7 - facial
CN9 - glossopharyngeal
CN10 - vagus
What are the nuclei in the medulla associated with?
Autonomic control
Cranial nerves
Motor/sensory relays
What autonomic nuclei centres are found in the medulla?
Cardiovascular centers
Respiratory rhythmicity centers
Emesis
Coughing
Sneezing
Which cranial nerves have nuclei in the medulla?
CN8 - vestibulocochlear
CN9 - glossopharyngeal
CN10 - vagus
CN11 - accessory
CN12 - hypoglossal
Which three relay nuclei are present in the medulla?
Nucleus gracilis
Nucleus cuneatus
Olivary nuclei
What does the nucleus gracilis and nucleus cuneatus do in the medulla?
Relay somatic sensory information to the thalamus
What does the olivary nuclei in the medulla do?
Relays information from spinal cord, cerebral cortex, and brainstem to cerebellar cortex
What two ridges are visible on the ventral side of the medulla?
Medullary pyramids
What are the medullary pyramids formed by?
Large motor corticospinal tracts
Where do most fibres decussate?
Medulla-spinal cord junction
What features are seen on a Weigert stain of a caudal medulla section?
Ventral horn is smaller
Dorsal horn is replaced by trigeminal sensory nucleus
Clear decussation of pyramids ventrally
What features are seen on a Weigert stain of a mid medulla section?
Dorsal column terminates
Prominent gracile and cuneate nuclei
What features are seen on a Weiger stain of a rostral medulla section?
Clear medial lemniscus at ventral midline
Inferior olivary nucleus
Hypoglossal nucleus
The pons contains nuclei for which four cranial nerves?
CN5 - trigeminal
CN6 - abducens
CN7 - facial
CN8 - vestibulocochlear
Which centres in the pons work with the medulla to maintain respiratory rhythm?
Apneustic and pneumotaxic
Which part of the brainstem is the raphe nuclei and reticular activating system found?
Pons
What is the tegmentum in the pons?
Dorsal portion of the pons, posterior to medial lemniscus
Are sensory fibres located posterior or anterior to motor fibres in the pons?
Posterior
What features are observed in a caudal section of the pons?
Trapezoid body between medial lemniscus and pontocerebellar fibers
What features are observed in a rostral section of the pons?
Superior cerebellar peduncles are prominent
Which nuclei are present in the midbrain?
Red nuclei
Cranial nerve nuclei
CN3 - occulomotor
CN4 - trochlear
Substantia nigra
Why is the red nucleus called ‘red’?
Highly vascularised nucleus
What information does the red nucleus receive and what information does it transmit?
Receives from cerebrum and cerebellum
Transmits information on subconscious motor commands concerned with muscle tone and posture
Where is the substantia nigra located in the midbrain?
Lateral to red nucleus
What naturally occurring pigment does the substantia nigra contain?
Melanin
What causes the substantia nigra to be darker in colour?
Melanin
Which brain stem nucleus contains melanin?
Substantia nigra in the midbrain
Which neurotransmitter does the substantia nigra release?
Dopamine
What effect does the substantia nigra have on the basal nuclei?
Inhibits the excitatory neurons of the basal nuclei
Which three tracts are present in the midbrain?
Motor tracts - pyramidal system
Sensory axons - spinothalamic
Cerebral peduncles
What are the two segments of the midbrain and what separates them?
Anterior (tegmentum)
Posterior (tectum)
Separated by the cerebral aqueduct
Where is the corpora quadrigemina located in the midbrain?
Dorsal surface of midbrain
What is the function of the corpora quadrigemina in the midbrain?
Relay center for vision and hearing
What two structures make up the corpora quadrigemina?
2 superior colliculi
2 inferior colliculi
What sensory process are the two superior colliculi in the corpora quadrigemina of the midbrain involved in?
Vision
What sensory process are the two inferior colliculi in the corpora quadrigemina of the midbrain involved in?
Hearing
What structures are visible on the caudal section of the midbrain?
Inferior colliculus
Periaqueductal grey matter
Medial longitudinal fasciculus
What structures on the rostral section of the midbrain?
Superior colliculus
Red nucleus
Substantia nigra
Crus cerebri