Neuroanatomy Flashcards
Define Rostral
Towards the face
Define Caudal
Towards the back
What are the 2 parts of the cerebrum
Telencephalon (outer brain)
Diencephalon (inner brain)
What are the 3 parts of the brain stem
Mid brain, pons, medulla
What are the 3 vesicles that develop from the embryonic neural tube?
The Forebrain
The midbrain
The hindbrain
What is the name of the forebrain?
Prosencephalon
What is the name of the midbrain?
Mesencephalon
What is the name of the hindbrain?
Rhombencephalon
What does the forebrain split into?
The prosencephalon divides telencephalon and diencephalon
What does the hindbrain split into?
It splits into the metencephalon and myelencephalon
What does the mesencephalon develop into in the mature brain?
The midbrain
What does the metencephalon develop into in the mature brain?
The pons and the Cerebellum
What does the myelencephalon develop into in the mature brain?
Medulla oblongata
What is white matter?
substance composed from the axons of neurones (due to the myelin being composed of white fat)
What is grey matter?
Cell bodies of neurones
What is the longitudinal fissure and what is its other name?
divides the left and right hemispheres of the brain and is also called the superior sagittal fissure
What is the Corpus Callosum?
A ‘thick body’ which connects the two hemispheres
At what part of the Spine does the spinal cord stop? (extended by nerve functions)
The start of the lumbar section of the spine
what is the name for the nerves extending past the end point of the spinal cord down the spine?
Cauda Equina (horse’s tail)
What are the two structures extending from the pons which transmit efferent motor fibres
the cerebral peduncles
Name (and preferably label) the two bulbous structures on the medulla
the olives and pyramids
What is a colliculi?
Pairs of bumps on the posterior surface of the midbrain
Name the 4 sections of the diencephalon
Thalamus, Hypothalamus, Epithalamus and Subthalamus
What is the function of the Thalamus?
‘The receptionist of the brain’, it works to relay and distribute information to the rest of the CNS
What is the function of the hypothalamus?
Functions in the Autonomic and nueroendocrine systems
What is the function of the epithalamus?
Includes the pineal gland, which releases melatonin and so is needed in regulating sleep
What is the function of the Subthalamus?
Involved in motor control
Name the sensory primary projection areas.
General Sensory - Postcentral gyrus
Visual - around calcarine sulcus
Auditory - Heschl’s gyrus
Name the area of the primary motor cortex
Precentral gyrus
Go label the areas of the brain
:)
Which hemisphere is dominant in most people?
the Left (opposite to the hand you write with)
What is Broca’s aphasia?
damage to the area of the brain surrounding language. intelligence and understanding is fully intact, motor damaged so inability to speak fluently, can’t form full sentences.
What is Wernicke’s aphaisa?
damage to the posterior language centre. can speak fluently but gibberish, cannot understand and answer questions
How much of all our oxygen consumption does the brain use?
around 20%
Name the two pairs of arteries that supply blood to the brain
Vertebral arteries and internal carotid arteries
Describe the path of the vertebral arteries
branch off of the subclavian arteries and travel up the spinal column, pass through the foramen magnum and fuse to become the basilar artery.
Describe the location and function of the anterior spinal artery
Caused by the fusing of two arteries (coming off of the left and right ventral arteries) in the rough midline of the medulla, goes down to supply the anterior aspect of the spinal cord
Describe the location and function of the Posterior Spinal artery
Two arteries than run down from the ventral to supply the posterior surface of the spinal cord
Aside from anterior/posterior, what is another difference between the two spinal arteries?
There is one anterior and 2 posterior
What is the PICA?
Posterior Inferior Cerebellum Artery
What is the AICA?
The Anterior Inferior Cerebellum Artery, it branches off of the inferior portion of the basilar artery (the level where the pons meets medulla)
What are the pontine arteries?
The large amount of tiny arteries given off by the basilar artery to supply the pons
What is the SCA?
Superior Cerebellar artery, branches off of the basilar artery to supply superior aspect of cerebellum
What is the PCA?
Posterior Cerebral arteries, supplies the posterior cerebrum (NOT cerebellum), last of the arteries supplied by basilar and therefore vertebral
What is the MCA?
Middle Cerebral artery, goes laterally from internal carotid
What are the ACA?
Anterior Cerebral Arteries, branch from internal carotid
What are the names of the arteries that form the circle of willis?
The posterior and anterior communicating arteries
What is the advantage of the circle of Willis?
Creates a ‘collateral circulation’ where if something gets blocked, blood has a way of bypassing it
What is an aneurysm?
when the walls of a blood vessel get weak and so start to bulge out and start to accumulate blood and can burst and haemorrhage
Where will all venous blood eventually drain into?
The internal jugular vein
Name the three meinges
The Dura mater, Arachnoid mater and pia mater (in order outside inwards)
Describe the dura mater
‘Hard mother’ it is fibrous, tough, role in protection of the brain
Describe the Arachnoid mater
called arachnoid because it looks like a spiders web, it is thin, delicate and many blood vessels run under it
Describe the pia mater
‘gentle mother’ microscopically thin, impossible to separate from the cortex of the brain
What is the flax cerebri?
The infolding of the dura mater that creates the superior sagittal sinus and separates the hemispheres
What is the tentori cerebi?
dura infoldings between the occipital lobes and cerebellum
What is different in the spinal cord meninges?
The dura mater is no longer in contact with bone, instead there is an epidural space (filled with fat). [subarachnoid still contains CSF]
Where is CSF produced?
in groups of specialised cells called the choroid plexus, located in the ventricles (exist in each ventricle)
Where does newly formed CSF leave the ventricles?
At the fourth ventricle through the Median aperture (foramen of Magendie) and Lateral apertures (foramina of Luschka)
How does the CSF transfer from the subarachnoid space into venous circulation
through arachnoid granulations/villi
What are the two pathways that transmit the sensations of pain and temperature?
Spinothalamic and Trigeminothalamic
Name a few modalities in the spinothalamic pathway and how they are carried
Pain, Temp, Simple touch and simple pressure, carried slowly by thin un/poorly myelinated nerve fibres
Define dermatome.
A specific region of skin of the body innervated by the sensory fibres of a single segmental spinal nerve (spinal cord segment)
How many neurones are there in the sensory pathway chain
3
What does Pseudounipolar mean?
A type of neurone that has one axon that quickly splits into 2 branches, making it look like it has 2 axon projections when it has 1
Describe the location of the spinothalamic pathway in the spinal cord
Mostly in the ventral white column, but it can reach around a little to be slightly in the lateral white column
Where does the first synapse occur in the spinothalamic pathway?
in dorsal grey horn or may ascends 1-2 segments then synapse -so 2nd neurone (2’) is what ascends spinothalamic tract
Where does the 2’ neurone cross over?
Ventral white commissure
Describe the Somatotopic organization of ascending fibres (Spinothalamic pathway)
Sensation from the arm will be the most medial, the trunk will be in the middle of the tract and the legs laterally
What happens to the spinothalamic tract after it reaches the medulla?
It changes names to become the spinal lemniscus
Where is the second synapse in the spinothalamic pathway?
In the thalamus to transit info to the 3’ neurone
Describe the location and subdivision of the trigeminal sensory nuclei
Runs through the length of the pons into the medulla. it has (superior to inferior) the Mesencephalic nucleus, the pontine nucleus and the spinal nucleus
At what part of the trigeminal nucleus are pain and temperature transmitted?
the Caudal part of the spinal nucleus
What anatomical part of the eye leads to a ‘blind spot’?
The optic disk
Where is the area of the eye that gives the highest level of visual acuity?
The Macula (leuta)
which layer of the eye is vascular?
The choroid
What is the purpose of the ciliary muscle?
To control the shape of the lens
True or False: the structures that make up the retina are not part of the Central Nervous System
False
Describe the visual pathway from the eye to the thalamus
light -> photoreceptors -> bipolar cells -> ganglion cells -> down the optic nerve to the thalamus
What area of the thalamus is involved in the visual pathway?
The Lateral geniculate nucleus
Does the optic nerve has meninges?
Yes as it is a part of the diencephalon and the CNS
What is papilloedema?
An increase in CDF pressure swells the subarachnoid space in the optic nerve causing a swelling of the optic disk. Causes blurred vision, headaches, vomiting
What is Meyer’s loop?
The inferior trajectory of the optic radiation transmitting the upper visual field to the lower bank of the calcarine sulcus
Where will the information for the macula get sent to?
The occipital pole (another layer of organization)
What is the name for a localised patch of blindness?
Scotoma
Define Anopia.
refers to the loss of one or more quadrants of the visual field (therefore hemianopia is loss of half of the visual field)
Define homonymous
Visual field losses are similar for both sides
What is the purpose of the middle ear?
To turn sound waves into mechanical waves
What is the purpose of the inner ear?
To turn mechanical waves into electrical impulses
What amount of the external ear is bony?
lateral 1/3 cartilage, medial 2/3 bony
What is the correct name for the eardrum
The tympanic membrane
How is the ear connected to the nasopharynx?
The middle ear is an air filled space connected by the Eustachian tube
Why is the middle ear such a high risk space?
Connected to nasopharynx – prone to infection
Connected to mastoid air cells – infection may spread to middle cranial fossa
Internal jugular vein lies inferior – thrombosis risk
Internal carotid artery lies anterior – link to pulsatile tinnitus
Traversed by chorda tympani and facial canal – infection risk
Which cranial nerve is involved in the cochlear?
The VIII, the vestibulocochlear nerve
The information from the cochlear is transmitted bilaterally. What does this mean?
Each half of the brain is sent information for both ears
Where does auditory information first synapse in the brain stem?
In the dorsal and ventral cochlear nuclei in the medulla
The more anterior in Heschl’s gyrus will detect ____ frequency sound
Lower, so the more posterior you go the higher the frequency
Define anxiety
A feeling or worry or nervousness, typically about an imminent event or something with an uncertain outcome (also has physical symptons)
between which vertebrae does the lateral grey horn with visceral fibres exist for the autonomic system?
(aside from the cranial nerves) T1-L2, S2-S4
how long is the neurone chain for the efferent visceral autonomic fibres?
- It has a preganglionic neurone in the CNS, a PNS autonomic ganglion and then a postganglionic neurone
which section of the autonomic nervous system has organised ganglia in a trunk close to the spinal column?
The sympathetic
The parasympathetic autonomic division has ganglia ____ to the target organ
Near
Which division of the autonomic system has a widespread effect and why?
The sympathetic because impulses can travel up and down the ganglion chain to interact with out organs
What neurotransmitter is used in the parasympathetic nervous system?
Acetylcholine
Which is the main parasympathetic nerve of the viscera of the trunk?
The Vagus nerve
What neurotransmitter is used in the sympathetic nervous system?
It uses acetylcholine in the preganglionic neurone interaction with the autonmic ganglion and noradrenaline in the target organ
What is the purpose of the meisner corpuscle?
For detecting light touch
What are nociceptors?
The simple free nerve endings in the peripheral that respond to tissue damage
Give three examples of chemicals released at the site of tissue damage and their function.
Prostaglandins, bradykinin and histamine, used to sensitise the nociceptor (irritants) to increase stimulus to increase likelihood of a response
What is a polymodial nociceptor?
A nociceptor that can respond to multiple types of stimuli and care more about the intensity of the stimulus rather than the type
What are the differences between the C and Adelta fibres nociceptors?
C are small, unmyelinated and focus on sharp pain and warm, Adelta are myelinated and focus on burning pain and cold
What is the purpose for ipsilateral mechanoreceptors in a pain response?
For a reflex arc
Describe the components of first pain
with fast Adelta fibres, easily localised, sharp, short duration (the immediate response)
Describe the components of second pain
with slower C fibres, burning/dull ache, slow onset, poorly localised, persistent
True or false: the spinal cord is laminated
True
What is the substania gelatinosa?
lamina I and II of the spinal cord where the afferent nociceptor fibres are
Where is pain relayed to in the brain?
The thalamus and somatasensory cortex
Describe the pain pathway from the head and neck
Afferent descend down the spinal trigeminal tract to the brain stem. Synapse in the pars caudalis. Axons ascend contralaterally in trigeminothalamic tract, projects to coretx.
How does the trigeminothalamic tract axons project to the cortex?
Via the Ventral posteromedial nucleus
True or false: the same type of pain is always the same regardless of context
False
What can the brain do to reduce pain
Release endogenous opiate-like chemicals
Give examples of conditions cannaboids are used to treat
Epilepsy, anxiety, cancer pain, MS
