Anatomy: Brain And Cranial Nerves Flashcards
What are the two components that make up the central nervous system?
Brain and spinal cord
The ridges on the surface of the brain are known as?
Gyrus’
The crevices in the brain are known as?
Sulci
What structures make up the midbrain?
- cerebellum
- medulla oblongata
- pons
What are the four lobes of the brain?
-frontal
-temporal
-occipital
-parietal
What lobe of the brain does the visual cortex sit within?
Occipital
What part of the midbrain controls fine motor movements?
Cerebellum
What does the medulla oblongata regulate?
- breathing
- heart and blood vessel function
- digestion
- sneezing
- swallowing
What does the pons control?
-breathing
- communications between different parts of the brain
- sensations like hearing, taste and balance
What part of the brain controls motor movement (particularly in the eyes and associated with hearing, taste and balance)
Midbrain
What is the relationship between the pons and the trigeminal nerve?
CN V is the only cranial nerve that arises directly from the pons
how many pairs of cranial nerves are there?
12
How are cranial nerves numbered?
From anterior to posterior and from lateral to medial
Name CN I
Olfactory nerve
Name CN II
Optic nerve
Name CN III
Occulomotor nerve
Name CN IV
Trochlear nerve
Name CN V
Trigeminal nerve
Name CN VI
Abducens nerve
Name CN VII
Facial nerve
Name CN VIII
Vestibulocochlear nerve
Name CN IX
Glossopharyngeal nerve
Name CN X
Vagus nerve
Name CN XI
Spinal accessory nerve
Name CN XII
Hypoglossal nerve
What is the protective covering of the brain and spinal cord known as?
The meninges
How many layers comprise the meninges?
Three
What is the most superficial layer of the meninges called?
Dura mater
How many layers of dura mater are there?
Two
What are the two layers of dura mater called?
- periosteal
-meningeal
What does the periosteal layer of dura mater attach to?
The skull
What does the meningeal layer of dura mater attach to?
Contacts middle membrane layer ( arachnoid mater)
There is a point in the cranial cavity where the periosteal and meningeal layers of the dura mater split off, forming what channel?
Dural venous sinuses
What is the middle layer of the meninges called?
Arachnoid mater
What is the purpose of the arachnoid mater?
Contains arachnoid granules which reabsorb cerebral spinal fluid
what is the cerebral spinal fluid filled space between the arachnoid mater and pia mater called?
Subarachnoid space
What is the deepest layer of the meninges called?
Pia mater
What is the purpose of the pia mater?
It coats the brain and blood vessels/nerves that enter/ leave the brain
What layer of the meninges follows the contours of the brain?
Pia mater
What artery sits between the periosteal and meningeal layers of the dura mater?
Middle meningeal artery
What are the two important features of the meningeal layer of dura mater?
- falx cerebri
- tentorium cerebelli
The layer of dura between the cerebral hemispheres is known as?
Falx cerebri
The layer of dura found between the cerebral hemispheres (above) and the cerebellum (below) is known as?
Tentorium cerebelli
What artery do the right and left vertebral arteries join together to form?
Basilar artery
What is beneficial about the circle of Willis system?
Contains lots of arteries that supply the brain. If there is a blockage in one of these arteries, the rest of the arterial supply may be able to account for that blockage.
What is the pneumonic used to remember the arteries within the circle of Willis?
Very
Big
Plants
Create
Important
Mindful
Atmospheres
Always
What are the arteries contained within the circle of Willis?
Vertebral arteries
Basilar artery
Posterior cerebral arteries
Communicating arteries
Internal carotid artery (right)
Middle cerebral artery (left)
Anterior cerebral artery
Anterior communicating artery
What structure does the pituitary gland sit within?
Cavernous sinus
What vein do dural venous sinuses aim to drain blood back to?
Right internal jugular vein
What are the three main sinuses of the falx cerebri region?
Inferior sagittal sinus
Superior sagittal sinus
Straight sinus
Where do the falx cerebri sinuses drain into?
The confluence of sinuses
What landmark of the skull is the confluence of sinuses located at?
Internal occipital protuberance
What are the two sinuses called that make up the confluence of sinuses?
- right transverse sinus
- right sigmoid sinus
Which sinus is prior to and drains into the right internal jugular vein?
Right sigmoid sinus
What sinus extends from the cavernous sinus and drains into the sigmoid sinus?
Superior petrosal sinus
What veins are responsible for returning blood back to cerebral sinuses?
Cerebral veins
What fluid occupies the ventricular system of the brain?
Cerebro-spinal fluid (CSF)
How many ventricles are there in the ventricular system of the brain?
Four
What are ventricles 1 and 2 referred to as?
Lateral ventricles
Where do the lateral ventricles drain?
3rd ventricle
Where does the 3rd ventricle sit?
Inferior to ventricles 1 and 2
What is the 4th ventricle continuous with?
The subarachnoid space
Where does the 4th ventricle sit within the brain?
Anterior to the cerebellum
What structure lines ventricles and produces cerebro-spinal fluid?
Choroid plexus
What recycles cerebro-spinal fluid into dural venous sinuses?
Arachnoid granulations
What are the different types of nerve modalities?
- somatic sensory
- somatic motor
- special sensory
- parasympathetic
- mixed
- visceral sensory (afferent)
What nerve modality does CN I have and why?
Special sensory ( sense of smell)
What nerve modality does CN II have and why?
Special sensory (sense of sight)
What type of nerve modality does CN III have and why?
Mixed
- somatic motor ( control of eye movement)
- parasympathetic ( control of eye muscle that causes constriction of pupil)
What nerve modality does CN IV have and why?
Somatic motor ( movement of eye muscles)
What type of nerve modality does CN V have and why?
Mixed
-Somatic motor (muscles of mastication)
- somatic sensory ( innervation of face)
What type of nerve modality does CN VI have and why?
Somatic motor (nerve supply to lateral rectus muscle of the eye)
what type of nerve modality does CN VII have and why?
Mixed
- somatic motor (muscles of facial expression)
- somatic sensory (innervates skin over the ear)
- special sensory (tongue)
- parasympathetic (sublingual + submandibular glands)
What type of nerve modality does CN VIII have and why?
Special sensory ( hearing and balance)
What type of nerve modality does CN IX have and why?
Mixed
- somatic motor (movement of pharynx)
- somatic sensory (posterior tongue)
- special sensory (taste)
- parasympathetic (parotid gland)
What nerve modality does CN X have and why?
Mixed
- somatic motor (palate)
- somatic sensory (skin over ear)
- special sensory (taste)
- parasympathetic
What type of nerve modality does CN XI have and why?
Somatic motor ( movement of trapezius and sternocleidomastoid)
What type of nerve modality does CN XII have and why?
Somatic motor ( muscles that control tongue)
Where do olfactory nerves pass through in the cranial cavity?
Cribiform plate
What are the two structures that make up the olfactory nerve?
Olfactory bulb and tract
What canal in the cranial cavity does the optic nerve pass through?
Optic canal
The structure where the two optic nerves cross over one another is known as?
Optic chiasma
Which cranial nerve is the only one to emerge from the posterior aspect of the midbrain?
CN IV (trochlear)
At which junction would CN VI be sat in the brain?
Sits at the junction between the pons and medulla oblongata
How many parts make up the trigeminal nerve?
Three
What are the three parts?
V1/a
V2/b
V3/c
What is V1/a of the trigeminal nerve called?
Ophthalmic nerve
What is V2/b of the trigeminal nerve called?
Maxillary nerve
What is V3/c of the trigeminal nerve called?
Mandibular nerve
What cranial nerve is the only one to emerge directly from the pons?
CN V ( trigeminal )
What parts of the trigeminal nerve are sensory?
V1/a and V2/b
What nerve modality does V3/c have?
Mixed
Sensory to skin of most of lower face
Motor to muscles of mastication etc.
Where does the separate motor root join with sensory part of V3/c?
At foramen ovale
How many divisions make up the cranial fossae and what are their names?
Three- anterior, middle and posterior cranial fossae
What cranial nerve passes through structures in the anterior cranial fossae?
CN I ( olfactory nerve)
What cranial nerves pass through structures in the middle cranial fossae?
CN II ( optic nerve)
CN III ( oculomotor nerve)
CN IV ( trochlear nerve)
CN V (v1,2,3) ( trigeminal nerve)
CN VI ( abducens nerve)
What cranial nerves pass through structures in the posterior cranial fossae?
CN VII ( facial)
CN VIII ( vestibulocochlear)
CN IX ( Glossopharyngeal)
CN X ( vagus)
CN XI ( spinal accessory)
CN XII ( hypoglossal)
Which cranial fossae is most important to know about inn dentistry?
Middle cranial fossae
Where the the sensory fibres from Va,Vb and Vc join together?
Trigeminal sensory ganglion
Where does the V3 motor root lie beneath and where does it pass through?
Beneath the trigeminal sensory ganglion and through the foramen ovale
How does V1/a enter/exit middle cranial fossa?
Through superior orbital fissure
How does V2/b enter/exit middle cranial fossa?
Through foramen rotundum
How does V3/c enter/exit middle cranial fossa?
Through foramen ovale
The middle meningeal artery passes through which foramen?
Foramen spinosum
In which fossa does the cavernous sinus sit?
Middle cranial fossa
What is the sheet of dura mater that forms the roof of the pituitary fossa known as?
Diaphragm sellae
What structure is inferior to the diaphragm sellae?
Pituitary gland
What cranial nerves pass through the cavernous sinus?
CN III ( oculomotor)
CN IV ( trochlear)
CN Va ( ophthalmic)
CN Vb ( maxillary)
