Brain Stem Flashcards
Cranial nerves
I. Olfactory II. Optic III. Oculomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial VIII. Vestibulocochlear IX. Glossopharyngeal X. Vagus XI. Accessory XII. Hypoglossal.
What makes up the brain stem?
Medulla oblongata
Pons
Midbrain
Olfactory nerve
CN I.
Sensory
Involved in smelling
Doesn’t go through thalamus
Optic nerve
CN II
Sensory
Vision
Oculomotor nerve
CN III
Motor
In midbrain.
Eye movement (incl. pupil dilation)
Trochlear nerve
CN IV
Motor
In midbrain
External muscles of eye.
Trigeminal nerve
CN V
Motor and sensory
Muscles of mastication, tongue, cheeks. Texture of taste.
In pons.
Abducens nerve
CN VI
Motor
Eye movements (abduction).
In pons
Facial nerve
CN VII
Motor and sensory
Saliva, tears, facial expression
In pons
Vestibulocochlear Nerve
CN VIII
Sensory
Ear, balance and hearing
In pons and medulla oblongata
Glossopharyngeal nerve
CN IX
Sensory and motor
Taste, swallowing salivating.
In medulla oblongata
Vagus nerve
CN X
Motor and sensory
Pharynx, larynx, parasympathetic response, increase digestion
In medulla oblongata.
Accessory nerve
CN XI
Accessory to vagus
Motor
Swallowing, taste in throat, SCM and traps.
In medulla oblongata
Hypoglossal nerve
CN XII
Motor
Tongue movement (speech and swallowing)
In medulla oblongata
Medulla Oblongata
Inferior part of brain stem
Foramen magnum –> pons
White matter contains all sensory and motor tracts between spinal cord and brain
Also contains nuclei that control vital brain function
And nuclei associated with CN VIII-XII
Pyramids
Protrusions of white matter on the anterior aspect of the medulla oblongata
Formed by corticospinal tracts that control voluntary moments of limbs and trunk
Decussation of pyramids
In medulla oblongata, just superior to junction with spinal cord, where 90% of axons cross over
Nuclei
Collection of neuronal cell bodies in CNS (= ganglion in PNS)
Cardiovascular centre
In medulla oblongata.
Regulates rate and force of heartbeat and diameter of blood vessels.
Medullary Respiratory Centre
In medulla oblongata
Adjusts the basic rhythm of breathing (with pontine respiratory group)
Vomiting Centre
In medulla oblongata.
Barfing.
Deglutition Centre
In medulla oblongata
Causes swallowing
Olive
In medulla oblongata.
Oval-shaped swelling that contains inferior olivary nucleus
Inferior olivary nucleus
In medulla oblongata
Receives input from cerebral cortex, red nucleus of midbrain, and spinal cord.
Neurons reach into cerebellum; allows inferior olivary nucleus to influence the cerebellum regarding muscle activity and learning new motor skills
Nuclei associated with what are located in the posterior medulla oblongata?
Sensations of discriminative touch, pressure, vibration, conscious proprioception (nuclei of the posterior column)
Gracile nuclei
In posterior medulla oblongata
Paired.
Nucleus of the gracile fasciculus (posterior column)
With Cuneate nucleus, involved with discriminative touch, pressure, vibration, conscious proprioception
Cuneate nuclei
Paired.
In posterior medulla oblongata
Nucleus of the cuneate fasciculus (posterior column)
With gracile nucleus, involved with discriminative touch, pressure, vibration, conscious proprioception
Medial lemniscus
Band of white matter connecting posterior column fasciluli (cuneate and gracile) to thalamus.
Extends through medulla, pons and midbrain.
Gustatory nucleus
In medulla oblongata
Part of gustatory pathway from tongue to brain.
Receives input from tastebuds.
Cochlear nuclei
In medulla oblongata
Part of auditory pathway from inner ear to brain.
Receive input from cochlea
The nuclei of what cranial nerves are found in the medulla oblongata?
VIII Vestibulocochlear IX Glossopharyngeal X Vagus XI Accessory nerves 9cranial poriton) XII Hypoglossal
Pons
Part of brain stem
Directly superior to medulla oblongata and anterior to cerebelllum.
“Bridge” between parts of the brains
Contains tracts and nuclei
Contains nuclei of CN V-VIII
Two main structural components of the pons
Ventral region (basilar pons) Dorsal region (pontine tegmentum)
Ventral region of pons
Forms large synaptic relay station consisting of scattered gray areas called pontine nuclei
Vestibular nuclei
In medulla oblongata
Equilibrium pathway from inner ear to brain
Pontine nuclei
Grey nuclei in ventral pons involved in conveying information in the motor cortex to the contra cerebellum.
Involved in learning new skills
Pontine respiratory group
Apneuristic area (in/exhalation; slows breathing) Pneumotaxic area (rhythm; stops firing of apneustic area)
Works with medullary respiratory group
Cranial nerves with nuclei in the pons:
V. Trigeminal
VI. Abducens
VII. Facial
VIII. Vestibulococchlear
Midbrain
AKA mesencephalon
Extends from pons to diencephalon
Associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation
Cerebral peduncles
In anterior midbrain
Consists of axons of the corticospinal, corticobulbar, and corticopontine tracts.
Conducts nerve impulses from motor area in cerebral cortex to spinal cord, medulla and pons.
Tectum
In posterior midbrain
Contains four rounded elevations: two superior colliculi and two inferior coliculi
Superior colliculi
Paired. In tectum (midbrain)
Reflex centres. Coordinates movements of the head, eyes, and trunk in response to visual stimuli.
ex. tracking a moving object, reading,
Inferior colliculi
Paired. In tectum (midbrain)
Part of auditory pathway.
Coordinates movements of head, eyes and trunk in response to auditory stimuli.
Involved with startle reflex
Substantia Nigra
Paired. In midbrain.
Nuclei involved in dopamine production
Also involved in subconscious muscle activities
Red nuclei
Paired. In midbrain.
Look reddish because of iron-containing pigment
Axons from cerebellum and cerebral cortex synapse in red nuclei. Help control involuntary movements of skeletal muscle.
Part of the indirect pathway (motor tract)
The nuclei of what cranial nerves are associated with the Midbrain?
III. Oculomotor
IV. Trochlear
Reticular formation
A diffuse network of interconnected nuclei located throughout the brainstem.
Connects the spinal cord, cerebrum, and cerebellum, and mediates the overall level of consciousness.
Reticular Activating System (RAS)
Ascending portion of reticular formation
Sensory axons that project to cerebral cortex
Involved in consciousness, arousal, filtering out of unimportant sensory input before it reaches consciousness (prevents sensory overload).
Affected by melatonin, anesthetics
From where does the RAS receive its input?
All senses except olfactory
Inactivation of RAS causes:
Damage to RAS causes:
Sleep
Coma
Descending portion of Reticular Formation
Connects cerebellum and spinal cord
Regulates muscle tone, heart rate, blood pressure, and respiratory rate
