Cranial Nerves and the Brainstem Flashcards
How can the brain be divided into different parts?
The diencephalon is composed of the thalamus and hypothalamus
What does is the brainstem composed of, what does it contain and what does it control?
Midbrain, pons and medulla
Contains many of the CNs’ nuclei
Contains centres that control heart rate, breathing rate etc.
What passes through the brainstem?
All ascending and descending pathways - many of these pathways synapse in brainstem nuclei before going off up to the brain / down to the rest of the body, or some pathways start within the nuclei in the brainstem
How is the cerebellum connected to the pons (in the brainstem)?
By 3 white fibre tracts called the 3 cerebellar peduncles
How many of the cranial nerves (CNs) have their cell bodies in the brainstem?
Why not CN XI?
What is the role of the Accessory nerve (AKA CN XI)?
9 of them - CN III TO CN XII (except CN XI)
Is called the Accessory Nerve - many say there isn’t a cranial part of the Accessory Nerve, as the nerve comes from the spinal cord, to the brain and exits via the vagus nerve (CN X), so it is really a spinal accessory nerve, found in the spinal cord and not the brainstem
Supplies motor fibres to 2 muscles: the sternocleidomastoid (neck) and the trapezius
Through which part of the brainstem is this a section of (the black line)?
What is this type of section / plane?
Through the midbrain:
Sagittal
Label this diagram (taken from a cross section of the midbrain, as shown in the previous card) and describe the 4 parts of this internal structure:
[4 parts relate to the entirety of the brainstem - midbrain, pons and medulla]
Tectum roof - back of the brainstem, behind the ventricular system e.g. the cerebral aquiduct etc.
Tegmentum - large part of the brainstem
Base - towards the front
What is this an image of?
What is the single cranial nerve that comes out of the dorsal aspect?
The back of the brainstem - posterior view, cerebellum has been removed
CN IV - trochlear nerve
What is the diamond shaped part of the brainstem that rests under the cut away cerebellum?
The diamond is the base of the 4th ventricle, CSF would be there (in the oval shape)
The roof of the 4th ventricle would be towards the right of the diamond, where the other structure sticks out
What are the 4 structures that are ascending / occupying the posterior aspect of the medulla?
What is the slight enlargements towards the top of the dorsal columns?
Dorsal columns - gracile and cuneate pathways
The point at which the cuneate and gracile pathways are synapsing onto their nuclei, which contain the cell bodies of the 2nd order sensory neurons
These 2nd order neurons are crossing over to the other side before going up to the brain
This image is the anterior aspect of the brain stem
What would be seen if the top part of the image had continued to be drawn?
The cerebral hemisphere
What are those structures?
The olfactory bulbs, the left olfactory bulb is on the right side of the image, and vice versa
What is the structure beneath the olfactory bulbs?
Optic tract
What structure hangs from that region?
Pituitary gland
What are these structures and which system are they a part of?
Mammillary bodies - part of the limbic system
Label all the CNs you can see on this diagram:
What is that large area on the diagram?
Cerebral peduncle - white fibre tract bringing information down from the cerebral hemispheres to the spinal cord
What occurs in that area (at the bottom) and what is it called?
And the enlarged / bulging area above?
Where 85 - 90% of the motor neurones cross from one side to the another to innervate the limbs - this point is called the decussation of the pyramids
Pyramids / pyramidal tract - contain corticospinal axons
Fill in the labels in this diagram (this is the posterior aspect of the brainstem):
Pineal gland - important for melatonin, circadian rhythms i.e. sleep-wake cycles
Superior and inferior colliculi - small bumps seen on the back of the midbrain, involved in visual and auditory pathways respectively
What is the pineal gland and why is it important?
Sleep-wake cycle / circadian rhythms
Controls the release of melatonin
What is meant by colliculi?
What are they responsible for?
Little hills
Superior colliculus = Visual pathways
Inferior colliculus = Auditory pathway
Fill in the labels and describe the diagram (the anterior aspect of the brainstem):