Neuro: Neuroanatomy 1 Flashcards
What is white matter?
Nerve cell axons; appears white due to myelin sheaths.
What is grey matter?
Primarily nerve cell bodies (but also consists of other nervous system cells and unmyelinated axons).
Are the deeper parts of the cerebrum mostly white or grey matter?
White matter (grey matter is mostly on the outer surface of the cerebrum).
What is the cortex? Is it mainly white or grey matter?
Outer part of the cerebrum and cerebellum, mainly grey matter.
Which lobe of the cerebrum contains the primary motor cortex and the prefrontal cortex (behaviour, personality, and decision making)?
Frontal lobe
Which lobe of the cerebrum contains the primary auditory cortex and the hippocampus (formation of memories)?
Temporal lobe
Which lobe of the cerebrum contains the primary somatosensory cortex (processing sensory information)?
Parietal lobe
Which lobe of the cerebrum contains the primary visual cortex?
Occipital lobe
Which part of the brain contains the hypothalamus and thalamus?
Diencephalon
Which part of the brain helps maintain posture and balance, and corrects fine movements?
Cerebellum
What separates the frontal and parietal lobes?
The central sulcus
What separates the temporal lobe below from the frontal and parietal lobes above?
The lateral sulcus (AKA the Sylvian fissure)
If the lateral sulcus is gently teased apart, what would you be able to see?
Part of the cerebral cortex called the insula.
What is the term for the parts of the frontal, parietal, and temporal lobes that cover the insula like lips around a mouth?
Opercula
What large groove separates the two hemispheres?
The longitudinal fissure.
What large bundle of white matter (axons) that connects the two hemispheres can be found on gently separating the longitudinal fissure?
The corpus callosum
When the brain is upside down, what two sets of nerve fibres are identifiable?
Olfactory tracts
Optic nerves
What structure, visible when the brain is upside down, allows for binocular vision by providing a point for some optic nerve fibres to cross over to opposite hemispheres?
The optic chiasm
The mammillary bodies, part of the diencephalon, are rounded structures visible just behind the optic chiasm and pituitary gland.
What functions are the mammillary bodies thought to provide?
Contributes to memory and learning, and spatial navigation.
What pair of fibre bundles in the midbrain connect the brainstem to the cerebrum?
The cerebral peduncles
What part of the cerebral peduncles are visible when the brain is upside down?
Crus cerebri
Which area of the frontal lobe, found on the dominant hemisphere (normally the left), is important for spoken language production?
Broca’s area
What area of the temporal lobe has a role in the perception of fear?
The amygdala
What area of the dominant hemisphere temporal lobe is important in understanding and coordinating spoken language?
Wernicke’s area
The limbic system is a group of structures in the medial margins of the hemispheres, including the hippocampus, amygdala, and various parts of the cortex and diencephalon.
Name five functions the limbic system is involved in.
- Emotion
- Memory
- Behaviour
- Endocrine
- Sensations of fear/pleasure
List the cranial meninges from innermost to outermost.
Pia
Arachnoid
Dura
(“PAD out”)
Which meninges is fibrous, thick, and does not stretch?
Dura
Which meninges is thin, flexible, made mostly of collagen fibres, and resembles a spider’s web?
Arachnoid
Which meninges lines sulci and is so thin it can’t be seen with the naked eye?
Pia
What do dural venous sinuses lie in between?
The endosteal and meningeal layers of the dura.
What is the term for the double layer of dura that lies in between the two cerebellum hemispheres?
Falx cerebelli
What is the term for the double layer of dura that goes down into the longitudinal fissure?
Falx cerebri
What is the term for the double layer of dura that lies in between the cerebellum and occipital lobes?
Tentorium cerebelli
What are arachnoid granulations?
Calcified bumps that protrude into venous sinuses and help reabsorb CSF.
Which dural venous sinuses connect the transverse sinuses to the internal jugular veins outside the skull to drain venous blood from the brain?
Sigmoid sinuses
What leaves an impression in the internal aspect of the posterior skull and is the site where the straight sinus meets the transverse sinuses and the superior sagittal sinus?
Confluence of sinuses
Which dural venous sinuses does the internal carotid artery pass through, along with some important nerves?
Cavernous sinuses
What is the blood-brain barrier formed of?
Layer of pia fused to endothelial cells of capillaries.
What two pairs of arteries supply the circle of Willis?
Internal carotid arteries (80%)
Vertebral arteries (20%)
Following an ischaemic stroke, a patient has changes to their vision.
What major artery of the circle of Willis is likely to be affected? Why?
Posterior cerebral artery (PCA).
PCA mostly supplies the occipital lobe which contains the visual cortex.
Which major artery of the circle of Willis supplies the vast majority of the lateral aspects and deep parts of the hemispheres, including parts of the motor and somatosensory cortices responsible for the face, arms, and trunk?
Middle cerebral artery (MCA).
Which major artery of the circle of Willis supplies the medial aspects of the frontal and parietal lobes, including parts of the motor and somatosensory cortex responsible for the lower limbs?
Anterior cerebral artery (ACA).
Disruption of which major artery of the circle of Willis can potentially threaten the function of all ascending and descending fibres, including motor control and sensation from the neck down? Why?
Basilar artery.
Basilar artery gives off small branches to supply the pons, which forms part of the pathway between the brain and spinal cord.
What three major arteries of the circle of Willis mainly supply the cerebellum and also parts of the brainstem?
Anterior inferior, posterior inferior, and superior cerebellar arteries (AICA, PICA, SCA).
In four steps, explain how venous blood drains from the brain.
- Cerebral venous blood drains into internal cerebral veins.
- These drain into larger external cerebral veins (can be seen on the surface of the brain).
- These drain into the dural venous sinuses.
- These drain into extracranial veins.
What veins cross the endosteal layer of dura to drain venous blood into the bones of the skull?
Emissary veins.
Where is CSF primarily produced?
In the lateral ventricles by specialised cells called choroid plexus.
What connects the lateral ventricles to the third ventricles to allow the flow of CSF from the lateral ventricles?
Interventricular foramen (foramen of Monro!)
What connects the third ventricle to the fourth ventricle to allow the flow of CSF from the third ventricle?
Cerebral aqueduct
Through what structure does CSF leave the ventricular system inferiorly to fill the subarachnoid space around the spinal cord?
Central canal
Through what two structures does CSF leave the ventricular system posteriorly and laterally to enter the subarachnoid space that surrounds the brain?
Median aperture of Magendie
Lateral apertures of Luschka
What separates the parietal and occipital lobes?
Parietal-occipital fissure
Name four parts of the limbic system.
Thalamus.
Hypothalamus.
Amygdala.
Hippocampus.
What fibrous joints join the bones of the skull together?
Sutures
What three distinct depressions that are seen when looking at the base of the skull from above?
The cranial fossae (anterior, middle, and posterior).
What function do the cranial foramina provide?
Allow nerves, arteries, and veins to pass in and out of the skull.
The frontal lobes rest in the anterior cranial fossa. What three bones make up the anterior cranial fossa?
Frontal bones, ethmoid bone, sphenoid bone.
Which parts of the ethmoid bone form part of the anterior cranial fossa?
Cribriform plate and crista galli.
Which part of the frontal bones form part of the anterior cranial fossa?
Orbital part.
Which part of the sphenoid bone forms part of the anterior cranial fossa?
Lesser wings.
What multiple foramina located in the anterior cranial fossa transmits olfactory fibres?
Cribriform plate foramina.
(smell a PLATE of food / olfactory nerve is CNI; 1st bed is a CRIB)
The middle cranial fossa is formed by parts of the temporal and sphenoid bones.
What lobes rest in the middle cranial fossa?
Temporal lobes.
The greater wing and body of the sphenoid bone help form the middle cranial fossa.
What small rounded cavity in the body of the sphenoid bone is where the pituitary gland is located?
Pituitary fossa (AKA sella turcica meaning “Turkish saddle”).
Which six foramina are located on each side of the middle cranial fossa?
“Ortho Consultants . Seriously Omit First . Rulling Out Syphilis . Claiming Competence”
Optic Canal
Superior Orbital Fissure
foramen Rotundum
foramen Ovale
foramen Spinosum
Carotid Canal
The superior orbital fissure transmits nerves for what function?
Movement and sensation of orbital region.
What nerve passes through the foramen rotundum?
Maxillary branch of trigeminal nerve (CNV).
“ROT in MAX for 5 years”
What nerve passes through the foramen ovale?
Mandibular branch of the trigeminal nerve (CNV).
“a real MAN drinks OVALtine 5 times a day”
What vessels and nerves pass through the foramen lacerum?
None! It is covered by cartilage.
What vessel passes through the foramen spinosum?
Middle meningeal artery.
(“Syphilis can cause meningitis”)
Which three parts of the brain rest in the posterior cranial fossa?
Occipital lobes, cerebellum, and brainstem.
What two bones form the posterior cranial fossa?
Mostly occipital bone, some of the temporal bone.
What are the four foramina located on each side of the posterior cranial fossa?
“In Jugs Hide Magnums”
Internal auditory meatus
Jugular foramen
Hypoglossal canal
Foramen magnum
Which three cranial nerves pass through the jugular foramen?
Glossopharyngeal (CN IX), Vagus (CN X), Accessory (CN XI).
Jugs XXX (1st three CNs with Xs)
What is the largest foramina in the skull?
Foramen magnum (CNS fibres leave skull and become spinal cord).
Which part of the orbit is thinnest and most likely to fracture?
Medial wall and floor of orbit.
What are adnexal structures? Give three examples.
Accessory structures that surround the eyeball to protect and support the functioning of the eye.
E.g. eyelids/eyelashes, conjunctiva, lacrimal glands/tear film.
The tarsal glands produce an oily secretion to help prevent tears evaporating.
Where are the tarsal glands?
In the lid margins of the eyelids.
What and where is the conjunctiva?
Protective highly vascular mucous membrane covering the anterior surface of the eye and posterior surface of the eyelids.
What direction does the tear film travel across the eye?
Medially; from the lacrimal gland to the lacrimal duct.
What are the three layers of the tear film?
Outer lipid, middle aqueous, and inner mucous layers.
What are the key properties of the three layers of the eye?
Outer = fibrous
Middle = vascular
Inner = photosensitive
What is the tough, fibrous, white part of the eye that plays a protective role in the outer layer?
Sclera
The cornea is continuous with the sclera but is transparent.
Give three functions of the cornea.
Provides a barrier, sensitive to pain (CN V), and has refractive powers.
If a patient has a functional corneal reflex; experiences pain of something in eye and blinks, what two cranial nerves are in tact?
Trigeminal nerve senses pain (CN V)
Facial nerve controls blinking (CN VII)
In the uvea (middle layer of the eye), what are the two sets of muscles in the iris?
Dilator and sphincter pupillae muscles (control pupil size)
What structure in the middle layer (uvea) of the eye produces the aqueous humour and contains the ciliary muscle which alters the shape of the lens?
Ciliary body.
What highly vascular structure in the middle layer (uvea) of the eye supplies blood to the retina and contains dark pigment to absorb stray light?
Choroid.
What is the accommodation reflex?
The ciliary muscle changes the shape of the lens to focus on near/distant objects.
What structure in the middle layer (uvea) of the eye may become opaque/cloudy (cataract)?
The lens.
The lens contains about 1/3 of the refractive power of the eye.
What structure has the majority (2/3) of refractive power?
The cornea.
What is the purpose of light refraction in the eye?
To focus light on the retina.
Is the lens thinner and more stretched when focussing on a near or distant object? Why?
Distant.
Light rays enter at less of an angle further away object is; lens needs to refract light less.
Why do the cornea and lens need to be bathed in aqueous humour?
They are both avascular. Aqueous humour provides nutrition to the cornea and lens.
Aqueous and vitreous humour are both important for maintaining intraocular pressure. Which is more posterior, is more gel-like, and helps maintain the shape of the eyeball?
Vitreous humour
The retina is in the inner layer of the eye and is the organ of phototransduction.
What does this mean?
It converts light into an electrical signal.
The retina dies quickly, leading to vision loss, if hypoperfused. Where does the retina get is blood supply from?
The choroid (outer part of retina) and the central retinal artery - branch of the ophthalmic artery (inner part of retina).
In opthalmoscopy, what is the “physiological blind spot” (called so because there are no photoreceptors here) seen as a reflective light with blood vessels emerging from this point?
The optic disc; where the optic nerve leaves.
What is dark circle in the centre of the retina seen on ophthalmoscopy, which contains many cone cells and is the centre of vision?
The macula
What is the part of the retina with the best visual acuity/detail, seen on ophthalmoscopy as a small pit in the centre of the macula, and contains only cone cells?
Fovea
List the visual pathway from the retina to the primary visual cortex in 7 steps.
“RON Often Chats OTT On Really Private Visual Concepts”
Retina - Optic Nerve
Optic Chiasm
Optic Tract - Thalamus
Optic Radiation
Primary Visual Cortex
What lobes does the optic radiation travel through before reaching the primary visual cortex in the occipital lobe?
Temporal and parietal
Does the left hemisphere receive only information from the right eye?
No, the primary visual cortex in each hemisphere receives information from both eyes about the contralateral visual field.
In the occipital lobe, what does the primary visual cortex lie on either side of?
The calcarine sulcus
The visual association cortex interprets visual information and gives it meaning. What lobe is the visual association cortex in?
Occipital but extends into parietal and temporal.
What two vessels does the straight sinus receive blood from?
Inferior sagittal sinus and the great cerebral vein.
Which artery provides blood supply to the motor cortex of the right leg?
The left anterior cerebral artery.
Would a stroke affecting the motor cortex result in a greater neurological deficit than the same sized stroke affecting the internal capsule? Why?
No. The internal capsule is where many tracts pass through, so a stroke in this area would result in a larger deficit.
What blood vessels supply the primary motor cortex?
Anterior and middle cerebral arteries.
What cranial nerve provides sensory innervation in the middle ear?
Glossopharyngeal (CN IX).
What type of joint is in between the chain of three auditory ossicles in the middle ear?
Synovial
The stiffness of the ossicular chain can be modified by which two muscles of the middle ear to dampen sound vibrations and reduce perceived volume?
Tensor tympani (acts on tympanic membrane) and stapedius (acts on stapes) muscles.
What two ionic fluids are contained in the cochlear?
Endolymph and perilymph.
What is the weakest part of the skull, prone to fracture if struck, and bleeding as the middle cerebral artery lies behind it?
Pterion (the ‘temple’)
Which six bones form the orbit?
Larger bones: frontal, sphenoid, zygomatic, and maxillary.
Smaller bones: ethmoid and lacrimal.
How many extraocular muscles are there and what do they do?
Seven; six move the eye, one retracts the upper eyelid.
What nerves supply the extraocular muscles?
“Larks Rise at 6, Swallows Out at 4, other at 3”
Lateral Rectus = Abducens CN VI
Superior Oblique = Trochlear CN IV
All other extraocular muscles = Oculomotor CN III
What fills the space between the eye, muscles, and nerves?
Fat
What are conjugate eye movements?
When both eyes do not necessarily perform the same movement at the same time e.g. to look to the left, left eye abducts, right eye adducts.
What eye movement is rotating the eye so the top of the eye rotates laterally?
Extorsion.
What eye movement is rotating the eye so the top of the eye rotates medially?
Intorsion.
What action on the eye does the levator palpebrae superioris muscle, innervated by oculomotor nerve (CN III) have?
Elevate the superior eyelid.
Which five extraocular muscles are innervated by the oculomotor nerve (CN III)?
Levator palpebrae superioris.
Superior, inferior, and medial rectus.
Inferior oblique.
The superior oblique extraocular muscle intorts, depresses, and abducts the eye.
What cranial nerve innervates the superior oblique?
Trochlear nerve (CN IV)
The lateral rectus muscle abducts the eye.
What cranial nerve innervates the lateral rectus?
Abducens nerve (CN VI)
What four extraocular muscles would you find originating on the common tendinous ring (also known as the annular tendon/annulus of Zinn) at the back of the orbit?
The four recti (superior, inferior, medial, lateral rectus).
Why does consensual pupillary response occur when a light is shone in one eye?
There is a connection between the left and right Edinger-Westphal nuclei, which sends instructions to the constrictor pupillae muscle in the iris.
What ossicle (middle ear bone) transmits movement of sound wave into movement of fluid, by tapping on the oval window of the cochlear?
Stapes
What part of the cochlear is important in detecting different frequencies of sound?
Basilar membrane.
What are the three ossicles in the middle ear?
Three small bones: malleus, incus, and stapes.
Using the image of a hammer, anvil, and stirrup, how do the three ossicles in the middle ear transmit sound waves vibrating the tympanic membrane to the cochlear?
When sound waves vibrate the tympanic membrane it moves the hammer (malleus). When the head of the hammer (malleus) strikes the anvil (incus), it passes vibrations to the stirrup (stapes) which hits the oval window in the cochlear.
Which part of the ear does the Eustachian tube join the ear with the nasal cavity?
Middle ear cavity.
What are the two main organs within the bony labyrinth of the inner ear cavity, within the temporal bone?
Cochlear and vestibular system.
What three fluid-filled bony structures make up the vestibular system, and allow perception of movement and acceleration by movement of the fluid?
The semicircular canals, utricle, and saccule.
How are the three semicircular canals positioned in respect to each other?
Perpendicular to each other in three dimensions.
The oculocephalic reflex is being able to maintain a fixed gaze whilst moving the head. How does this connection of vision and movement occur?
The vestibular system in the labyrinth sends signals via the vestibulocochlear nerve to the brainstem where there are connections to extraorbital muscle nerves (occulomotor, trochlear, and abducens).
