LAB 8: Brain and Cranial Nerves Flashcards
What are the 3 layers of meninges?
Dura, arachnoid, and pia mater
What does dura mater do?
Covers and protects the brain
What is the pia mater connected to?
Attached to the surface of the cortex
What are arachnoid granulations?
Visible granules adhering to the pia mater.
What is the surface of the cerebrum called?
Cortex
What is the surface of the cerebrum called?
Cortex
What does convoluted mean?
Folded
What are the different folds called within the surface of the cerebrum?
Gyri, fissures and sulci
What are raised parts of folds called?
Gyri
What are deep depressions called?
Fissures
What are shallow depressions called?
Sulci
What is the corpus callosum?
A bridge of nerve axons connecting the left and right sides of the cerebrum.
What is the tectum?
Dorsal surface of the midbrain, roof of midbrain
What are the 4 bumps of the tectum?
2 superior colliculi
2 inferior colliculi
What does the superior colliculi receive?
Visual information and sends motor information to muscles of the head and neck.
What does the inferior colliculi receive?
Auditory information and sends motor information to muscles of the head and neck.
Where are smells received?
By neurons in the olfactory bulb
Axons from within neurons of the olfactory bulbs travel through the perforations of the ethmoid bone and end up where?
In the mucosa of the dorsal nasal cavity.
Olfactory signals travel in the olfactory tracts to the olfactory cortex, located where?
On the ventromedial surface of the cortex
How come vivid memory can be elicited by certain smalls?
The olfactory cortex overlaps with the cortices that process memories.
Where is the optic nerve located?
Just posterior to the olfactory tracts
Anterior to the chiasma are the __________; posterior to it are the _________.
Optic nerves, optic tracts
What is dorsal to the chiasma?
Midbrain
What is connected to the main body of the brain by the pituitary stalk?
Pituitary gland
What does the pituitary gland produce?
Many of the body’s hormones
What are pons?
Round bulb in the brain stem, posterior to the pituitary
The pons is a bridge that connects what?
Cerebrum and cerebellum
What information passes through the pons?
Most sensory information from the body to the cortex, and all the motor information from the cortex to the body.
What does the medulla carry?
All the information between the body and the brain.
What do the vital centers of the medulla regulate?
Heart rate and respiratory rate
What can damage to the medulla result in?
Immediate death
Where is the entry point for the oculomotor (CN III) nerve?
Between the pons and midbrain, near midline
Where is the entry point for the trigeminal (CN V) nerve?
Lateral pons; a large, thick nerve
Where is the entry point for the abducens (CN VI) nerve?
Between the pons and medulla, near midline
Where is the entry point for the facial (CN VII) nerve?
Between the pons and medulla, lateral to the abducens
Where is the entry point for the oculomotor (CN VIII) nerve?
Between the pons and medulla, lateral to facial
Where is the entry point for the glossopharyngeal (CN IX) nerve?
Anterior, lateral medulla
Where is the entry point for the vagus (CN X) nerve?
Lateral medulla, posterior to CN IX
Where is the entry point for the accessory (CN XI) nerve?
Lateral medulla, posterior to CN X
Where is the entry point for the hypoglossal (CN XII) nerve?
Medial medulla
What separated the two lateral ventricles?
Septum pellucidum
What are the 3 locations where cerebrospinal fluid is produced?
Subarachnoid space (40%) General Ependymal lining of brain ventricle (30%) Choroid plexus (30%)
Explain the path of CSF circulation.
- Two lateral ventricles empty into medially located 3rd ventricle.
- Travels via cerebral aqueduct from 3rd to 4th ventricle (between cerebellum and pons)
- Then flows out though 1 of 3 pores on the 4th ventricle to circulate around external surface of brain.
- Then absorbed via arachnoid villi into the space (sinus) between the periosteal and meningeal dura mater.
- The sinus collects venous blood and ultimately drains into the internal jugular vein
What is the space between the periosteal and meningeal dura mater called?
A sinus
What is the cerebellum essential for?
Motor coordination, balance, and posture
The cerebellum is divided into white and gray matter that gives a tree-like appearance called what?
Arbor Vitae
The cerebellum has a huge surface area for its size and contains more than half of what?
All the neurons of the entire brain
What is the pineal body?
A small mass of tissue attached to the posterior margin of the thalamus
What does the pineal body produce and what is it involved in?
The hormone melatonin and is involved in setting circadian rhythms
What do projection tracts carry information where?
Information into or out of the cortex
What do commissural tracts carry information where?
Information from one side of the brain to the other
What do association tracts carry information where?
Information from different regions of the same hemisphere
What is arachnoid mater?
Loose tissue that is not attached to the cerebrum
How thick in the pia mater?
Only a few cells thick
Pia mater is firmly attached the other outer most layer of ___________.
The cerebrum
What is the outer most layer of the cerebrum called?
The cortex
What does the cortex contain?
Primarily large neuronal cell bodies and is a lighter pink than the white matter.
How many layers is the cerebrum divided into?
6
What makes the outermost layer of the cerebrum different than all the rest?
It contains a small amount of neurons; lighter in color, and contains primarily the dendrites of the neurons in lower layer.
What is the primary content of white mater?
Axons
What does white mater look like on a slide (4X)?
Darkest pink colour on a slide, had many while ‘holes’ or vertical lines that indicate the presence of myelin.
What are stellate cells?
Rounded neuron with many dendrites.
What is another name for stellate cells?
Thinking cells
Where do stellate cells do?
Receive input from many different areas of the brain,
Integrate this info,
and sand their decision to the pyramidal cells.
What input does stellate cells receive?
What you see, how you feel emotionally, how you feel physically (tired or hungry), memories, and ability to judge probable outcomes.
What are pyramidal cells?
They come in different sizes and their cell bodies are somewhat triangular. There is a large apical dendrite pointing towards the surface.
What do pyramidal cells do?
Carry out decision that was made by stellate cells.
Where do pyramidal cells send their output?
To other cortical regions.
Some of the pyramidal cells output goes to motor regions of the brain to do what?
Coordinate your muscles to perform the desired action
What is a synapse?
Connections between the many cells of the cortex
What do oligodendrocytes make?
Myelin to cover axons
What are astrocytes?
Small dark nuclei that are typically found close to blood vessels, where they help to form the blood-brain barrier
Although cranial nerve originate from the brain, they are primarily part of what NS?
Peripheral NS
The cranial nerves serve the head neck with an exception to which nerve? What does it supply?
The vagus nerve – runs down to thoracic and abdominal cavities.
All except for which 2 CN arise from the brain stem and pass through the foramina of the skull to travel to their destinations?
Olfactory and optic
The inability to follow a stimulus with the eyes could indicate dysfunction to what cranial nerves?
Oculomotor III, IV, or abducens VI.
The inability to smoothly tract the finger with both eyes indicates impairment of function of extrinsic eye muscles or of which cranial nerves?
Oculomotor III, IV, or abducens VI.
Oculomotor CN III contains parasympathetic fibres that control what?
Pupil constriction
What may result from the swelling in the cranium that compresses CN III?
Cerebral hemorrhage
Lack of sensation within the mandibular, maxillary, or ophthalmic regions indicates loos of function of what CN?
Trigeminal nerve V
Weakness or asymmetries may indicate loss of function of what CN?
Facial nerve VII
What are fibers called that cross from one side of the brain to the other?
Decussation (e.g. Optic CN)
Where are superior and inferior colliculi found?
In the midbrain
What is the function of the thalamus?
Key role in motor control by replying signals providing feedback loop
What is the function of the hypothalamus?
Forms floor and part of walls of 3rd ventricle,
major control center of endocrine and autonomic NS
What is the function of the epithalamus?
Forms covering and lining of many organs
What are the 3 structures of the diencephalon?
Thalamus, hypothalamus, epithalamus
What are the 4 glial cells in the CNS?
Oligodendrocytes – speed up signal conduction in the nerve fiber
Ependymal cells – produce CSF
Microglia – checkup on brain tissues several times a day
Astrocytes – contract the blood capillaries and stimulate them to form blood-brain barriers.
