Neuro Flashcards
What muscles can change the stiffness of the ossicular chain?
Stapedius and tensor tympani.
Name 4 cerebellar nuclei.
- Dentate.
- Emboliform.
- Globose.
- Fastigial.
where is the primary motor cortex?
pre-central gyrus
Which of the cavities of the cochlea are filled with perilymph?
Scala vestibuli and scala tympani.
where does venous blood exit the cranium?
jugular foramina
other name for primary motor cortex?
Brodmann’s Area 4
what comes before the relative refractory period?
the absolute refractory period
What are the anatomical divisions of the nervous system?
The CNS (brain and spinal cord) and the PNS (cranial nerves and spinal nerves).
- What does Cn2 innervate?
- What are it’s functions?
- Innervates: retina.
- Function: vision.
Define axonal transmission.
Transmitting information from A to B.
Where do sympathetic nerves come from?
T1 -> L2 spinal nerves.
- What does Cn4 innervate?
- What are it’s functions?
- Innervates: superior oblique.
- Functions: movement of eyeball.
What are the vestibular apparatus?
- Otolithic organs: utricle and saccule.
2. 3 Semi-circular canals.
Describe the I’MAuditory pathway.
Inferior colliculi -> inferior brachium -> medial geniculate body.
- Concerned with the reflex of looking towards a loud noise.
What is the cauda equina?
Spinal nerves from the lower spinal cord that hang obliquely downwards.
What are the signs of UMN weakness?
- Increased muscle tone.
- Hyper-reflexia.
- Spasticity.
- Minimal muscle atrophy.
What do the middle cerebellar peduncles convey?
They send information from the primary motor cortex about the motor plan to the cerebellum - corticopontocerebellar tract.
What tracts are known as the dorsomedial system?
DCML.
What is the action(s) of medial rectus on the eyeball?
- Adduction.
Where do the two optic nerves meet?
At the optic chiasm. The images from the two eyes are fused here.
What is the peripheral nervous system?
The nervous system outside the brain and spinal cord. It includes the cranial nerves (except 1 and 2) and the spinal nerves.
- What does Cn1 innervate?
- What are it’s functions?
- Innervates: olfactory epithelium.
- Function: olfaction.
What tracts are known as the ventrolateral/anterolateral system?
Spinothalamic tracts.
- What does Cn6 innervate?
- What are it’s functions?
- Innervates: lateral rectus.
- Function: eye movement, abduction.
where do the fibres of the vestibulospinal tract decussate?
they dont
What nerve fibres innervate golgi tendon organs?
Afferent type 1b sensory nerve fibres (inhibitory).
What week does the neural tube fuse?
Week 4.
What does the metencephalon form?
- Cerebellum.
- Pons.
What is the function of microglia?
They are the immune cells of the CNS - phagocytic and immune surveillance.
What lies beneath the arachnoid mater?
The subarachnoid space containing CSF and arteries.
Where do the purkinje cell axons go to?
Most go to the dentate nucleus. They then pass into the superior cerebellar peduncle to decussate, and then travel to the thalamus and the red nucleus.
where does the external jugular vein receive blood from?
exterior of the cranium, deep parts of the face
What neurones innervate muscle spindles?
Gamma motor neurones.
What are the characteristic features of MS?
MS comes and goes and its symptoms are exacerbated after having a shower.
What do the two vertebral arteries form?
The basilar artery.
What is the conus medullaris?
The tapered, lower end of the spinal cord.
What does the telencephalon form?
- The cerebral hemispheres.
A 30-year-old woman noticed that her face had become progressively droopier whilst putting her make-up on in the mornings. Weeks later she began to experience double vision, and found it progressively more tiring and difficult to chew all the food in her mouth when eating. What is the problem?
Myasthenia Gravis (characterised by progressive weakness and tiredness. Actions like chewing become much harder. It is a neuromuscular junction disease where the Ach receptors are blocked).
where does the rubrospinal tract decussate?
medulla
What is an endorphin?
A peptide with opiate like effects. They inhibit the release of substance P.
What does the mesencehpalon form?
- Midbrain.
- Colliculi.
How do somatic motor neurones differ from autonomic motor neurones?
Somatic motor neurone leaves the spinal cord and synapses straight onto the effector. Autonomic motor neurones have a pre-ganglionic and post-ganglionic component and so synapse at the ganglia and then at the effector.
which tract carries pain sensation?
lateral spinothalamic tract
What does the anterior cerebral artery supply?
The medial aspect of the hemispheres and the corpus callosum.
What sensations does the spinothalamic pathway convey?
- Lateral spinothalamic - pain and temperature.
- Anterior spinothalamic - crude touch.
Briefly describe the pathway of afferent pain transmission.
Nociceptors, A delta and C fibres, synapse with secondary afferent neurones in the dorsal horn of the grey matter. Substance P is released. Interaction amongst afferent neurones and interneurones determines the activity of secondary neurones. The signal is carried via the spinothalamic tract to the thalamus. Third order neurones then ascend to the somatosensory cortex.
What is the effect of stimulating opioid receptors?
It can reduce neuronal sensitivty and so reduce the pain sensation.
- What are the functions of Cn9?
- Sensory functions: general sensation, taste, chemo/baroreception.
- Motor functions: Swallowing (larynx and pharynx are elevated).
- Parasympathetic function: salivation.
What does the myelencephalon form?
- Medulla oblangata.
What site does brain stimulation affect?
Sub-thalamic nucleus.
What sensations is the lateral spinothalamic tract responsible for?
Pain and temperature.
Give 3 functions of the cranial meninges.
- Protects the brain and spinal cord form injury.
- Provides a framework for cerebral and cranial vasculature.
- Provides a space for the flow of CSF.
Where is the falx cerebelli located?
Between the 2 lobes of the cerebellum.
What sensation is the anterior spinothalamic tract responsible for?
Crude touch.
A 30-year-old man presents with increased muscle tone, brisk reflexes and fasciculations. Which spinal tract is likely to be affected?
Corticospinal (UMN and LMN weakness).
Are there any synapses within the descending pathways?
No. At the termination of the descending tracts, the neurones synapse with a lower motor neurone. (All the neurones within the descending motor system are UMNs).
What is the dermatome for the thumb?
C6.
function of the tectospinal tract?
controls head turning to visual stimulus
What are the two types of deafness?
- Conductive - sound is blocked from getting through.
2. Sensory neural - the problems are with the nerves.
What is the ventral stream?
The ‘what’ stream. It is thought to be involved in identification and recognition. It travels through the temporal lobe.
if damaged, cn1 will cause what
anosmia on the ipsilateral side
What is the potential of the scala media?
+80mV.
Briefly describe the stretch reflex.
The muscle is stretched and intrafusal muscle fibres are stimulated -> sends afferent impulses along 1a neurones -> alpha motor neurone -> efferent impulses to extrafusal muscle fibres -> contraction.
where does the internal jugular vein receive blood from?
brain, superficial parts of the face and the neck
What is the function of myelin?
Insulates and allows rapid conduction of action potentials along an axon.
Describe the corticobulbar tracts.
Originate in the primary motor cortex, descends through corona radiata and internal capsule to the brainstem. The fibres terminate on motor nuclei of cranial nerves. They synapse with LMN’s which carry motor signals to the face and neck.
What are the 3 cavities of the cochlea?
- Scala vestibuli.
- Scala media.
- Scala tympani.
Where do the vestibulospinal tracts originate and what are they responsible for?
- Originate from vestibular nucleus.
- Responsible for muscle tone and postural control.
- Remains ipsilateral.
What embryonic part of the brain is the medulla oblangata formed from?
Myelencephalon of Rhombencephalon.
does CN1 have afferent, efferent or both components?
afferent (sensory only)
Which arteries supply about 80% of blood to the brain?
The internal carotid arteries.
What is voluntary motor control?
Goal directed (conscious) or habitual (unconscious/automatic). E.g. running, walking talking etc.
Describe A delta fibres.
- Small nerve fibres but larger than C fibres.
- Thinly myelinated.
- They have a high activation threshold.
What is the function of the limbic system?
The limbic system is involved with emotion, behaviour, long-term memory, olfaction and motivation. It is also thought to have a role in learning.
what innervates extrafusal muscle fibres?
alpha motor neurones
Where in the thalamus do the DCML and spinothalamic tracts synapse?
In the ventral posterio-lateral division (VPL) of the nucleus of thalamus.
What is the action(s) of inferior rectus on the eyeball?
- Depression.
- Extorsion.
- Adduction.
What is myasthenia gravis?
An autoimmune disease; antibodies destroy Ach receptors.
Which lobes of the brain does the loop of optic radiation responsible for the lower visual field travel through?
Travels through the parietal lobes.
Name 4 disorders associated with basal ganglia dysfunction.
- Huntington’s disease.
- Parkinson’s disease.
- ADHD.
- OCD.
What is the function of the ossicles?
To transmit vibrations from the tympanic membrane to the oval window.
What is the function of the cerebellum?
Precise control, fine adjustment and coordination of motor activity based on continual sensory feedback. The cerebellum decides HOW you do something. It computes motor error and adjusts commands and projects it back to the motor cortex.
where are golgi tendon organs situated?
at the junction of a skeletal muscle and a tendon
Approximately how much CSF do we have?
120ml.
What structures connect adjacent stereocilia?
Tip links.
what do extrafusal muscle fibres do?
contract muscles
What would be the affect of damage to the cerebellar vermis?
Balance problems due to loss of postural control. Difficulty in sitting and standing up.
what does the reticulospinal tract do?
acts to facilitate or inhibit the activity of various descending tracts
What nerve provides sensory innervation to the nasopharynx?
Maxillary branch of the trigeminal - Cn 5(b).
what do muscle spindles detect?
muscle relaxation and extension
Name the 3 elements that make up the blood-brain barrier.
- Capillary endothelial cells.
- Basement membrane.
- Astrocytic end-feet.
- What is the name of Cn2?
- Where does it exit the skull?
- Sensory, motor or both?
- Optic.
- Optic canal (ethmoid bone).
- Sensory.
What are the functional divisions of the nervous system?
Somatic (voluntary control) and autonomic (involuntary control, further subdivided into sympathetic and parasympathetic).
where does the tectospinal tract originate?
superior colliculus
what innervates the skeletal muscle?
alpha motor neurones = extrafusal = skeletal
the middle one third of the spindle is associated with which sensory nerves?
type 1a afferent sensory nerves
Name 4 ascending spinal pathways.
- DCML.
- Spinothalamic.
- Spinocerebellar.
- Spinoreticular.
What occular muscle does Cn 4 innervate?
Superior oblique.
Mutation of what protein can result in duchenne?
Dystrophin.
What are the sub-divisions of the prosencephalon?
- Telencephalon.
- Diencephalon.
What nerve provides general sensation to the outer ear?
Cn 10.
What do the superior cerebellar peduncles do?
They connect the midbrain and the cerebellum and carry mostly efferent fibres.
Where are dural venous sinuses located?
In between the endosteal and meningeal layers of dura.
how does cn1 enter the cranial cavity
via small holes in the cribiform plate of the ethmoid bone
What would pouring ice cold water in the external auditory meatus cause?
Convection currents in the semi-circular canals which results in nystagmus.
What do the semi-circular canals detect?
Angular acceleration.
- What is the name of Cn1?
- Where does it exit the skull?
- Sensory, motor or both?
- Olfactory.
- Cribriform plate of ethmoid bone.
- Sensory.
% of fibres in the lateral vs anterior corticospinal tracts?
85% lateral
15% anterior
Withdrawal reflex: what does reciprocal innervation of antagonistic muscles explain?
It explains why the contraction of one muscle induces the relaxation of the other; this permits the execution of smooth movements.
What is the role of the insula in pain recognition?
The insula contributes to the subjective perception of pain. It is where the degree of pain is judged.
A man is feeling very distressed as he woke up being unable to feel the right side of his face and his right arm and leg. What lobe is affected?
The parietal lobe (somatosensory cortex). Feel is the key word here.
What is the action(s) of superior oblique on the eyeball?
- Intorsion.
- Depression.
- Abduction.
what does the anterior corticospinal tract do?
controls muscles of the trunk
Define pain.
An unpleasant sensory and emotional experience associated with actual tissue damage.
where do the axons of lower motor neurones terminate?
on an effector/ muscle
What nerve innervates tensor tympani?
Cn 5.
What nerve provides general sensation to the middle ear?
Cn 9.
What structures lie anteriorly to the cerebellum?
The pons and medulla. The 4th ventricle lies in between these and the cerebellum.
Where are Cn 1 nuclei located?
Olfactory bulb.
What is a berry aneurysm?
A sac-like out pouching that will progressively enlarge until it ruptures resulting in haemorrhage.
Where is the insula located?
Deep in the lateral sulcus.
What occular muscles does the superior branch of Cn 3 innervate?
- Levator palpebrae superioris.
- Superior rectus.
What spinal nerves innervate the biceps reflex?
C5/6.
name the two types of lower motor neurone
alpha and gamma motor neurones
What is the helicotrema?
Where the scala vestibuli and scala media meet.
what innervates the spindle muscle fibres?
gamma motor neurones = intrafusal = spindle
Where do cerebral veins drain into?
Into dural venous sinuses.
What are the 3 structures that make up the organ of corti?
- Hair cells.
- Supporting cells.
- Auditory nerve fibres.
what does the vestibulospinal tract do?
controls muscles involved in balance and posture
Where is a berry aneurysm likely to occur?
At branching points in the circle of willis, especially at the anterior communicating artery.
What do golgi tendon organs measure?
Mechanoreceptors that measure changes in tension of a muscle.
What is the response of golgi tendon organs if they detect a change in tension?
They inhibit alpha motor neurones to prevent muscle contraction if the force gets too great.
What would be the signs of a complete spinal cord lesion?
- Weakness in all muscle groups below the lesion.
- Complete sensory loss below lesion.
- Spasticity and hyperreflexia.
which part of the muscle spindle is contractile?
the two ends are contractile
What do the inferior cerebellar peduncles convey?
Ipsilateral muscle proprioception, balance and vestibular inputs - vestibulocerebellar tract and dorsal spinocerebellar tract. Also fibres from inferior olivocerebellar tract.
What is the dorsal stream?
The ‘where’ stream. It is thought to determine the objects spatial location. It travels through the parietal lobe.
What 3 bones make up the ossicular chain?
Malleus, incus and stapes.
Where do the optic tracts terminate?
Lateral geniculate body in the thalamus.
What descending pathways are described as extrapyramidal?
Vestibulospinal, rubrospinal, tectospinal, reticulospinal - responsible for involuntary and automatic control of all musculature, such as muscle tone, balance, posture and locomotion.
where is CSF reabsorbed?
into the superior sagittal sinus
What nerve innervates stapedius?
Cn 7.
where do the fibres of the the dorsal column-medial lemniscal system decussate?
at the medulla
What is the reason behind the signs of PD?
Not enough dopamine.
What would be the affect on the visual field if there was a complete lesion of the left optic nerve?
Total left eye blindness.
Is the base or the apex of the basilar membrane more sensitive to high frequency sounds?
The base.
Where does the spinothalamic tract decussate?
Within the spinal cord, 2-3 spinal segments above.
Where do parasympathetic nerves come from?
Cn 3, 7, 9 and 10, S2 -> 4.
What is the papez circuit?
A circuit that connects the main structures of the limbic system. It is involved in memory and emotions.
What is the action(s) of lateral rectus on the eyeball?
- Abduction.
Describe C fibres.
- They are the smallest nerve fibres.
- Unmyelinated and so have slow conduction speeds.
- They have a high activation threshold meaning they detect selectively nociceptive stimuli.
How is the neuronal resting potential maintained?
3Na+ are pumped out of the cell for every 2K+ pumped in. This process requires ATP. There are many Na+/K+ transport pumps.
What efferent signals do the superior cerebellar peduncles convey?
Efferent signals from the dentate nucleus that go to the red nucleus and thalamus.
Do the finger tips have lots of muscle fibres or few muscle fibres?
Few muscle fibres. This allows for greater movement resolution.
where are muscle spindles found?
in skeletal muscles
where does the reticulospinal tract originate?
from cells found in the pons and medulla
Define dermatome.
An area of skin with a sensory nerve supply from a single root of the spinal cord.
Where is the straight sinus located?
In the midline of the tentorium cerebelli.
What is the smallest bone in the human body?
The stapes.
What are the signs of parkinson’s disease?
- Tremor.
- Bradykinesia.
- Rigidity.
What is the function of the vestibular hair cells?
They detect changes in motion and position of the head by stereocilia transduction.
- What is the name of Cn6?
- Where does it exit the skull?
- Sensory, motor or both?
- Abducens.
- Superior orbital fissure.
- Motor.
What is the origin and insertion of levator palpebrae superioris?
Origin: common tendinous ring.
Insertion: Upper eyelid.
- What is the name of Cn11?
- Where does it exit the skull?
- Sensory, motor or both?
- Accessory.
- Jugular foramen.
- Motor.
Name 3 locations where the dura mater folds inwards as dural reflections?
- Falx cerebri.
- Tentorium cerebelli.
- Falx cerebelli.
What neurones innervate muscle fibres.
Alpha motor neurones.
What are the functions of rods in the eye?
Rods are important for peripheral vision.
You are carrying out an eye examination on a patient who is looking at the tip of your nose. Behind you, on your left hand side, is a tall medical student. What would be the patients’ retinal representation of the image of this students’ face?
The retinal image is converted from right to left and reversed. The students face is now in left lower corner.
(Medical student is stood on your left but that is the patients right).
What is the dermatome for the big toe?
L5.
What sinuses form the confluence of sinuses?
The straight sinus and the superior sagittal sinus.
Where is the majority of CSF produced?
In the lateral ventricles (greatest amount of choroid plexus here`).
A 40-year-old removal man felt immediate back pain and a popping sensation after lifting a heavy box. The next day he noticed he was tripping over his right foot as it was dragging along the floor. What is affected?
Lower motor neurones (he has a slipped disc. The LMN nerve roots coming out of the spinal cord have been damaged).
What does the diencephalon form?
- Thalamus.
- Hypothalamus.
What is involuntary motor control?
Eye movements, facial expressions, posture, diaphragm etc.
What does the middle cerebral artery supply?
The lateral surface of the hemispheres.
A patient is diagnosed with a lesion to Cn 3, how would the eye appear to the examiner?
‘down and out’ due to unopposed action of lateral rectus and superior oblique.
how are fibres in the dorsal columns arranged?
topographically
Where is the tentorium cerebelli located?
The tentorium cerebelli is a thick fibrous roof lying over the posterior cranial fossa and the cerebellum.
Where is the 3rd ventricle formed in the embryo?
Diencephalon.
What do neural crest cells develop into?
Schwann cells, pigment cells, adrenal medulla, dorsal root ganglia, Cn 5, 7, 9 and 10.
What sensations does the DCML pathway convey?
Fine touch, 2-point discrimination and proprioception.
What do the middle cerebellar peduncles do?
They connect the pons and the cerebellum and they ‘tell’ the cerebellum about voluntary motor outputs.
Which cranial nerve can be tested in the unconscious patient by observing pupillary constriction in response to light?
Optic - CN2.
Neurones communicate via 2 types of synapses. What are they?
- Chemical - majority.
2. Electrical.
What is the function of the vestibular system?
Balance and spatial orientation.
Where are the dural venous sinuses located?
Between the endosteal layer of dura and the meningeal layer.
What are the pluripotent stem cells that lie within the neural folds?
Neural crest cells.
- What is the name of Cn9?
- Where does it exit the skull?
- Sensory, motor or both?
- Glossopharyngeal.
- Jugular foramen.
- Both: sensory and motor and parasympathetic.
What is the entry/exit foramina for the labyrinthine artery?
Internal acoustic meatus.
Where is the falx cerebri located?
It lies in the longitudinal fissure between the cerebral hemispheres.
What are the signs of myasthenia gravis?
Weakness and tiredness. Actions like chewing become progressively much harder.
What do the internal carotid arteries supply?
The anterior and middle parts of the cerebrum and the diencephalon.
What are the 2 connective tissue sheets of dura mater?
- Endosteal layer - lines the cranium.
2. Meningeal layer.
What afferent signals do the superior cerebellar peduncles convey?
Ipsilateral information on proprioception and balance from the ventral spinocerebellar tract.
A man presents to the stroke unit being unable to move/feel his right arm, right sided facial drooping and slurred speech. Which artery has been affected?
Left middle cerebral artery.
What neurotransmitter is in deficit in huntington’s disease?
GABA.
Where are vestibular hair cells located?
In the utricle and saccule and in 3 ampullae at the base of the semi-circular canals.
What structures are contained within the limbic system?
Hippocampus, amygdala, fornix, mammillary bodies, cingulate gyrus, anterior nuclei of thalamus, hypothalamus.
what is the function of wernicke’s area?
comprehension of speech
What is the action(s) of superior rectus on the eyeball?
- Elevation.
- Intorsion.
- Adduction.
what is the resting potential of the neurone mostly governed by?
permeability of the membrane to K+ ions
What are the corticospinal tracts responsible for?
The control of voluntary muscles. Anterior - axial muscles. Lateral - limb muscles.
- What does Cn11 innervate?
- What are it’s functions?
- Innervation: trapezius and sternocleidomastoid.
- Functions: movement of head and shoulders.
What vein passes through the superior orbital fissure?
Superior ophthalmic vein
how are the fibres of the corticospinal tract organised?
somatotopically
lower limbs -lateral
upper limbs- medial
In huntington’s disease what area of the basal ganglia and what neurotransmitter are affected?
- Striatum (caudate nucleus).
- GABA.
What occular muscle does Cn 6 innervate?
Lateral rectus.
Briefly describe the withdrawal reflex.
The limb is withdrawn from noxious stimuli. Afferent fibres synapse on motor neurones in spinal cord. The response is ipsilateral flexion (same side as noxious stimuli) and contralateral extension.
What region of the vertebral column has the least capacity for flexion?
The thoracic region; this is due to the presence of the ribcage.
What would be the affect on the visual field if there was a complete lesion of the optic chiasm?
Bipolar hemianopia. (Left eye - left sided blindness, right eye - right sided blindness).
the external jugular vein is formed by the juntion of which 2 veins?
posterior facial vein and posterior auricular vein
how much of the blood to the cerebrum comes from the vertebral arteries (as a %)
5%
What is Brown-Sequard syndrome?
Hemi-section of the spinal cord.
What is a LMN?
A neurone that carries signals to effectors. The cell body is located in the brain stem or spinal cord.
Is the CNS or the PNS protected by the blood-brain barrier?
The CNS.
Is the base or the apex of the basilar membrane wider?
The apex.
Which hair cells have 95% afferent nerve fibres?
Inner hair cell’s (OHC’s - efferent).
Where does the vestibulocochlear nerve terminate
In the petrous part of the temporal bone
What embryonic part of the brain is the pons formed from?
Metencephalon of Rhombencephalon.
What type of pain are A delta fibres responsible for?
The sensation of a quick, sharp, localised pain; ‘first pain’.
What type of pain are C fibres responsible for?
C fibres respond to high intensity stimuli. They are responsible for a slow, deep, spread-out pain; ‘second pain’.
Where do the mossy fibres come from?
They come from the pons via the middle cerebellar peduncle.
What is spina bifida?
Failure of the neural tube to close in the spinal cord region.
- What does Cn3 innervate?
- What are it’s functions?
- Innervates: medial, superior and inferior rectus muscles and inferior oblique and levator palpebrae superioris.
- Motor function: movement of eyeball.
- Parasympathetic function: constriction and accommodation.
Tight junctions prevent the passage of fluid into the ventricles. Why is this important?
It means that the volume and composition of CSF can be closely controlled.
Briefly describe the pathway of venous drainage starting at the great cerebral vein.
Great cerebral vein -> straight sinus -> transverse sinus -> sigmoid sinus -> internal jugular vein -> jugular vein -> brachiocephalic vein -> SVC.
What is the stretch reflex?
A very simple, monosynaptic reflex. If a muscle is stretched it responds by contracting.
What embryonic part of the brain is the midbrain formed from?
Mesencephalon.
How many rows are there of:
a) Inner hair cells?
b) Outer hair cells?
a) 1 row of IHC’s.
b) 3 rows of OHC’s.
What are the vertebral arteries a branch of?
The subclavian arteries.
Describe how the brain maintains its blood flow in response to hypovolemia.
Cerebral autoregulation. Hypovolemia leads to a decrease in BP and so the cerebral arterioles dilate more so as to maintain blood flow.
how long does the relative refractory period last?
5-10ms
Damage to the anterolateral system will present with what symptoms?
Contralateral loss of pain and temperature sensation.
Which cavity of the cochlea houses the organ of corti?
The scala media.
Where does the substantial nigra project to?
The striatum.
What are muscles spindles composed of?
Intrafusal fibres. (They are embedded in muscle - extrafusal fibres).
How can opioids be used as analgesia?
They bind to inhibitory G-protein coupled receptors in the brain/spinal cord.
where does the straight sinus receive blood from?
inferior sagittal sinus and great cerebral vein
What is ependyma?
A thin-epithelial like structure lining the ventricles.
Which part of the brain has a role in addiction?
The insular cortex.
What is the function of the blood-brain barrier?
It protects the brain by preventing the passage of some substances from the circulation into the nervous tissue.
which ascending tract carries touch and proprioception signals?
dorsal column-medial lemniscal system
which kind of muscle fibres are muscle spindles made of?
intrafusal muscle fibres
where does the pyramidal tract originate?
ventrolateral (motor) thalamic nucleus
- What is the name of Cn10?
- Where does it exit the skull?
- Sensory, motor or both?
- Vagus.
- Jugular foramen.
- Both: sensory and motor and parasympathetic.
What information do muscle spindles provide?
How much each muscle is stretched.
Do the fibres decussate in the spinocerebellar tracts?
No! They go to the ipsilateral cerebellum.
What are the internal carotid arteries branches of?
The common carotids. Arise from bifurcation at the same level as the upper border of the thyroid cartilage.
What would be the affect on the visual field if there was a complete lesion of the right optic tract?
Left homonymous hemianopia. (Left side blindness of both eyes).
which system is characterised by fast conduction velocities?
dorsal column-medial lemniscal system
where is broca’s area
left frontal lobe (left inferior frontal gyrus)
What are the 3 layers of the cerebellar cortex?
- Molecular (outermost).
- Purkinje.
- Granular.
define motor unit
motor neurone and all the muscle motor units it innervates
- What are the functions of Cn10?
- Sensory functions: general sensation.
- Motor functions: speech and swallowing.
- Parasympathetic functions: control over CV, respiratory and GI systems.
What are the 2 components of a refractory period?
The absolute refractory period which is followed by the relative refractory period.
Where do the vertebral arteries enter the skull?
Through the foramen magnum.
Give 2 examples of fast neurotransmitters. Do fast neurotransmitters have short or long lasting effects?
- Ach, GABA.
- Short lasting effects.
what does the posterior communicating artery connect?
internal carotid and posterior cerebral arteries
What does the ethmoidal artery supply?
Anterior part of the nasal cavity and the nose
- What does Cn12 innervate?
- What are it’s functions?
- Innervation: intrinsic and extrinsic muscles of the tongue.
- Function: movement of the tongue.
- What is the name of Cn4?
- Where does it exit the skull?
- Sensory, motor or both?
- Trochlear.
- Superior orbital fissure.
- Motor.
Where do the rubrospinal tracts originate and what are they responsible for?
- Originate from red nucleus.
- Responsible for assisting motor functions.
- Contralateral.
What does the great cerebral vein drain?
Deep brain structures.
What can cause UMN weakness?
MS, brain tumour, stroke.
- What is the name of Cn5?
- Where does it exit the skull?
- Sensory, motor or both?
- Trigeminal.
- V(1)-superior orbital fissure. V(2)-foramen rotundum. V(3)-foramen ovale.
- Both: sensory and motor.
which kind of muscle fibres are skeletal muscles made of?
extrafusal muscle fibres
Describe the corticospinal tracts.
Originate in the primary motor cortex, descends through corona radiata and internal capsule to the medullary pyramids. 90% decussates here and becomes the lateral corticospinal tract; the remaining 10% forms the anterior corticospinal tract. The anterior tract then decussates through the anterior white commissure. Both tracts terminate in the ventral horn.
What are the lobes of the cerebellum hemispheres called?
The anterior and posterior lobes.
What neurotransmitter do parasympathetic nerves use at organs?
Ach.
Where does the facial nerve exit the skull? (Not enter)
Stylomastoid foramen
What happens to the stereocilia when the basilar membrane vibrates?
They bend. This opens the hair cells’ ion channels and there is an increase in auditory nerve firing.
What is the dermatome for the knee?
L3.
Where does the spinal cord end?
a) in an adult.
b) at birth.
c) in the embryo.
a) L2.
b) L3.
c) runs the entire length of the vertebral column.
- What are the functions of Cn7?
- Sensory function: taste.
- Motor function: facial movement and tension of ossicles.
- Parasympathetic function: salivation and lacrimation.
a stroke affecting the blood supply to the occipital lobe would result in what?
contralateral homonymous hemianopia
What are the 2 inputs into the cerebellum?
- Climbing fibres.
- Mossy fibres.
What are the two types of stroke?
- Ischaemic.
2. Haemorrhagic (intracerebral or subarachnoid).
- What is the name of Cn12?
- Where does it exit the skull?
- Sensory, motor or both?
- Hypoglossal.
- Hypoglossal canal.
- Motor.
What neurotransmitter do sympathetic and parasympathetic nerves both use at ganglia?
Ach.
What is the visual pigment in the eye?
Rhodopsin.
which side of the spine do lower motor neurones leave?
anteriorly/ ventrally
efferennt
signals carried away from the brain and spinal cord
Why would ptosis (drooping of the eyelid) occur?
If there was a loss of innervation to levator palpebrae superioris.
main centre involved in parkinson’s?
basal ganglia
afferent
signals carried to the brain and spinal cord
- What does Cn9 innervate?
- Sensory innervation: posterior 1/3 of tongue, middle ear, pharynx, carotid bodies.
- Motor innervation: stylopharyngeus.
- Parasympathetic innervation: parotid gland.
Name 4 substances contained within the CSF.
- Protein.
- Urea.
- Glucose.
- Salts.
What would be the affect on the visual field if there was a lesion of the parietal loop of the left optic radiation?
Right homonymous inferior quandrantanopia. (Right lower quadrant of both eyes affected).
where are most neurotransmitters synthesised?
neurone cell bodies
Which meningeal layers are highly vascularised?
The dura and pia mater. The arachnoid mater is avascular.
What is hydrocephalus?
An accumulation of CSF in the ventricular system. Often due to a blockage in the cerebral aqueduct.
A woman presents to the stroke unit being unable to move/feel her left leg/foot. Which artery has been affected?
Right anterior cerebral artery.
What is the function of the round window?
It vibrates with opposite phase to vibrations entering the inner ear through the oval window. This moves the fluid in the cochlea which means that hair cells of the basilar membrane will be stimulated and that audition will occur.
What are the 2 main arteries that supply blood to the brain?
- Vertebral arteries.
2. Internal carotid arteries.
What are the 5 fundamental processes of neurotransmission?
- Manufacture.
- Storage.
- Release.
- Interaction with post-synaptic receptor.
- Inactivation.
Describe the DCML pathway.
Fine sensation is detected by touch or proprioception receptors. Afferent signals are carried along 1st order neurones to the dorsal columns and up to the medulla where they synapse. 2nd order neurones decussate in the medulla and travel up to the thalamus where they synapse. 3rd order neurones then travel through the internal capsule to the somatosensory cortex.
Briefly describe how dopamine is produced.
Tyrosine -> L-dopa -> dopamine.
What is the action(s) of inferior oblique on the eyeball?
- Extorsion.
- Elevation.
- Abduction.
What are the signs of huntington’s disease?
- Chorea (jerky, involuntary movements).
- Dementia.
- Personality change.
where are the cell bodies of lower motor neurones located?
ventral horn of the spinal cord
What is the role of the cingulate gyrus in pain recognition?
It provides an emotional response to pain.
Where are the lateral ventricles formed in the embryo?
Telencephalon.
Where do the climbing fibres come from?
The come from the olivocerebellar nuclei via the inferior cerebellar peduncle.
What is the function of dystrophin?
It provides structural stability to muscle cell membranes.
What nerve provides sensory innervation to the oropharynx?
Glossopharyngeal - Cn 9.
What would be the affect of damage to the cerebellar hemispheres?
Ipsilateral impaired limb coordination.
which arteries supply the cerebellum and what are they branches of?
superior cerebellar artery (SCA)- branch of basilar
anterior inferior cerebellar artery (AICA)- branch of basilar
posterior inferior cerebellar artery (PICA)- branch of vertebral
What does myasthenia gravis affect: LMN, UMN, neuromuscular junctions?
Neuromuscular junctions.
A patient can understand what you’re saying but is unable to construct sentences in response. What part of the brain is affected?
Broca’s area in the dominant frontal lobe.
Where would you insert an epidural needle?
Between the dura mater and vertebrae in order to inject anaesthesia.
what causes the voltage gated Na+ channels to close?
they close after a particular time
what is the rough threshold potential of a neuronal cell membrane?
-60mV
Where is the somatosensory cortex located?
Post-central gyrus in parietal lobe.
Define nociceptive pain.
Pain derived from actual damage to non-neural tissue, it is due to the activation of nociceptors.
How do men and women differ in their response to pain?
Women report pain more readily but can tolerate more pain than men.
What occular muscles does the inferior branch of Cn 3 innervate?
- Medial rectus.
- Inferior rectus.
- Inferior oblique.
which sensory fibres run from the golgi tendon organ to the spinal cord?
1b sensory fibres
What is the entry/exit foramina for the superior ophthalmic vein?
Superior orbital fissure.
What sinus does the great cerebral vein drain into?
The straight sinus.
some cutaneous (skin) receptors are phasic and others are tonic. what do phasic and tonic mean?
phasic = able to adapt quickly tonic = adapts slowly
where does the lateral corticospinal tract decussate?
at the level of the medullary pyramids
- What does Cn5 innervate?
- What are it’s functions?
- Sensory innervation: face, scalp, cornea, nasal and oral cavities, anterior 2/3 of tongue, dura mater.
- Motor innervation: muscles of mastication and tensor tympani.
- Sensory function: general sensation.
- Motor functions: open and close the mouth. Tenses tympanic membrane.
what is the “less skilled” version of the lateral corticospinal tract?
rubrospinal tract
what effect does afferent impulses from the golgi tendon organ have?
inhibition of the associated alpha motor neurones to regulate muscle tension at a normal range and protect the muscle from overload
How do dural venous sinuses and veins outside the skull communicate?
Via emissary veins.
What are the terminal branches of the internal carotid arteries?
The middle and anterior cerebral arteries.
What are spinal reflexes?
- Involuntary, physiological responses to stimuli e.g. withdrawing your hand when you touch something hot.
- Unlearned and instinctive: unconditioned responses.
What do the vertebral arteries supply?
The posterior cerebrum and the
contents of the posterior cranial fossa.
What is the function of hair cells?
Through transduction they convert mechanical stimuli into electrochemical activity and they also have a role in amplification.
where in the primary motor cortex are lower limbs and muscles of the face represented?
lower limbs - medially
muscles of the face - laterally
what connects the internal carotid arteries to the posterior cerebral arteries?
posterior communicating artery
What is the somatic nervous system?
A part of the peripheral nervous system that handles voluntary control of body movements.
change in membrane potential due to an action potential?
-70mV to +30mV
What supplies the upper spinal cord?
Anterior and posterior spinal arteries (branches of vertebral arteries)
Define neuropathic pain.
Pain caused by a primary lesion or dysfunction of the nervous system.
What are the 3 primary vesicles?
- Prosencephalon (forebrain).
- Mesencephalon (midbrain).
- Rhombencephalon (hindbrain).
What is the affect on movement in cerebellar injury?
Movements are slow and uncoordinated.
What can be found in Meckel’s cave?
The ganglia of the three branches of the trigeminal nerve
What is the clinical significance of emissary veins?
They represent a possible route for infection to spread into the cranial cavity.
Which part of the brain is activated in acupuncture?
Cingulate gyrus.
What is the loop of optic radiation responsible for the upper visual field called?
Meyer’s loop. It travels through the temporal lobes.
Are C fibres myelinated or unmyelinated?
Unmyelinated.
during repolarisation do voltage-gated K+ channels open or close?
K+ channels open
a stroke in which lobe would cause memory loss?
temporal lobe
what supplies the primary motor cortex?
middle cerebral artery supplies most of the primary motor cortex BUT the medial aspect (leg areas) are supplied by the anterior cerebral artery
What structure connects the two cerebellar hemispheres?
The vermis.
What sensation does the spinoreticular tract convey?
Deep/chronic pain.
What neurotransmitter do sympathetic nerves use at organs?
Noradrenaline.
Where would you insert a lumbar puncture needle?
At the L3/L4 level in the sub-arachnoid space in order to take CSF.
what do intrafusal muscle fibres do?
body position, proprioception (perceiving location of body parts)
Where are Cn 2 nuclei located?
Lateral geniculate body.
What vitamins are needed to ensure the neural tube fuses.
B9 (folic acid) and B12.
what supplies the basal ganglia?
lenticulo-striate arteries (branches of the anterior and middle cerebral arteries/ ACA & MCA)
What are the functions of cones in the eye?
Cones are important for visual acuity and colour vision.
Where do the extrapyramidal tracts originate?
The brainstem.
What does the nasociliary nerve supply?
Parasympathetic fibres to the ciliary body
How long does the refractory period last?
5-10ms.
what is the resting potential of a neuronal cell membrane?
-70mV
A woman presents to the stroke unit with complete right sided visual field loss. Which artery has been affected?
Left posterior cerebral artery.
what does the anterior communicating artery connect?
the left and right cerebral arteries
Give 4 treatments for pain.
- Analgesics.
- Acupuncture.
- Exercise.
- Hypnotherapy.
what innervates intrafusal muscle fibres?
gamma motor neurones
where does the majority of the blood supply to the cerebrum come from?
internal carotid artery (80%)
What is the neuronal resting potential?
-70mV.
What do the inferior cerebellar peduncles do?
They connect the medulla and the cerebellum and convey muscle proprioception and vestibular inputs.
Where do the tectospinal tracts originate and what are they responsible for?
- Originate from tectum nuclei (superior and inferior colliculi).
- Responsible for head turning in response to visual and auditory stimuli.
What is the direct pathway of the basal ganglia?
The direct pathway is for when we want to make movement. The motor cortex excites the striatum which inhibits the globus pallidus internal meaning the thalamus is no longer inhibited and can send excitatory signals to the motor cortex = MOVEMENT!
when in the resting state, the plasma membrane of neuornes contains more of which OPEN channel: K+ or Na+?
more open K+ channels in resting state
What does the middle meningeal artery supply?
Skull and dura mater
What would be the signs of Brown-Sequard syndrome?
- Ipsilateral weakness and loss of motor function below the lesion.
- Ipsilateral loss of proprioception, 2-point discrimination and fine touch.
- Contralateral loss of pain and temperature sensation 2-3 spinal segments below the lesion.
What is the only cranial nerve to emerge from the dorsal aspect of the brainstem?
Trochlear Cn 4.
What structures make up the basal ganglia?
- The striatum: putamen and caudate nucleus.
- Globus pallidus: internal and external segments.
- Subthalamic nucleus.
- Substantia nigra.
What are some symptoms of cerebellar injury?
- Loss of coordination.
- Inability to judge distances.
- Intention tremor.
- Staggering, wide based walking.
- Weak muscles.
What can cause LMN weakness?
Slipped disc, neuropathies.
compare the speed of the afferent fibres in muscle spindles and golgi tendon organs
muscle spindles posses faster afferent fibres than golgi tendon organs
What is the output from the cerebellum?
Purkinje cell axons.
What is a neuromuscular junction?
A chemical synapse formed by the contact between a motor neurone and a muscle fibre.
Give 4 features of pain.
- Pain is always subjective.
- It is a sensation.
- It is always unpleasant.
- It is an emotional experience.
What is the scala media filled with?
Endolymph.
What is the function of the outer ear?
It gathers sound energy and focuses it on the tympanic membrane; this vibrates the tympanic membrane. The outer ear also amplifies sound.
What vessels lie in the cavernous sinus?
- Cn 3, 4, 5(1), 5(2) and 6.
- Internal carotid artery.
where are the cell bodies of skin receptor neurones?
dorsal root ganglion
Where do the reticulospinal tracts originate and what are they responsible for?
- Originate from reticular formation.
2. Responsible for spinal reflexes.
What are the 3 meningeal layers?
- Dura mater (outermost).
- Arachnoid mater.
- Pia mater (inner most).
which kind of summation do tactile recepetors show?
temporal and spatial
- What is the name of Cn7?
- Where does it exit the skull?
- Sensory, motor or both?
- Facial.
- Internal acoustic meatus.
- Both: sensory and motor and parasympathetic.
What does the ligamentum flavum connect?
Connects the laminae of adjacent vertebrae.
A 42-year-old female has presented with weakness in her left leg. She has been seen previously in your clinic two years ago for visual disturbance and sensory loss over the left forearm. These symptoms persisted for several weeks but then gradually resolved. Her symptoms are exacerbated following a shower. What is the problem?
Multiple Sclerosis (characterised by the fact it comes and goes. Exacerbated after a shower is also a key feature of this disease).
Name 5 descending pathways.
- Corticospinal.
- Vestibulospinal.
- Rubrospinal.
- Tectospinal.
- Reticulospinal.
Where is the superior orbital fissure
Between the lesser and greater wings of the sphenoid bone
What is the stria vascularis?
A structure involved in the active transport of K+ into the scala media.
What is the reason behind the signs of HD?
Too much dopamine.
Define motor unit.
A single alpha motor neurone and all the muscle fibres it innervates.
What is an UMN?
A neurone that is located entirely in the CNS. Its cell body is located in the primary motor cortex.
Why is the cavernous sinus of clinical importance?
If this sinus is infected Cn 3, 4, 5(1), 5(2) and 6 and the internal carotid artery could be affected.
How does the cerebellum control coordination, precision and timing of movements?
It compares the brain’s intentions with actual actions and makes any necessary modifications.
What structures are present on the IHC’s and OHC’s?
Stereocilia.
which motor neurones innervate muscles directly?
lower motor neurones
what does the lateral corticospinal tract do?
controls muscles involved in fine limb movement
where is wernicke’s area?
left temporal lobe (left posterior superior temporal gyrus)
what detects changes in muscle tension?
golgi tendon organ
- What is the name of Cn8?
- Where does it exit the skull?
- Sensory, motor or both?
- Vestibulocochlear.
- Internal acoustic meatus.
- Sensory.
Which dorsal column would an afferent signal from the lower limb use?
The gracile fasciculus (medial part of dorsal column). They then synapse at the gracile nucleus of the medulla.
What are the sub-divisions of the rhombencephalon?
- Metencephalon.
- Myelencephalon.
What are the 2 components of an intervertebral disc?
- Nucleus pulposus.
2. Annulus fibrosus: concentric layers of collagen surrounding the nucleus pulposus.
where do upper motor neurones originate?
motor region of the cerebral cortex or brainstem
What is the Melzack Wall pain gate?
The idea that non-painful input can close the ‘gate’ to painful input and so prevent it from reaching the CNS. Non-noxious stimuli can prevent pain as the large fibres can override the small pain fibres. It is a physiological explanation for why ‘rubbing it better’ can help.
- What does Cn10 innervate?
- Sensory innervation: pharynx, larynx, oesophagus, external ear, aortic bodies, thoracic and abdominal viscera.
- Motor innervation: soft palate, larynx, pharynx.
- Parasympathetic innervation: CV, respiratory and GI systems.
What are the characteristic features of a cervical vertebra?
- Small vertebral body.
- Transverse foramen for vertebral arteries.
- Bifurcation of spinous processes (except C7).
- Triangular intervertebral foramen.
When should the neural tube fuse?
By the end of the 4th week.
Does function of a muscle affect how many muscle fibres there are?
Yes! The finger tips have few muscle fibres because they require greater movement resolution.
What does the posterior cerebral artery supply?
The occipital lobe.
What is the entry/exit foramina for the ophthalmic artery?
Optic canal.
What is the function of the spinocerebellar tracts?
They carry unconscious proprioceptive information to the ipsilateral cerebellum.
is the dorsal column-medial lemniscal system ascending or descending?
ascending
What spinal nerves innervate the ankle reflex?
S1/2.
Stimulation of which part of the brain can result in profound analgesia?
PAG.
What is the function of the basal ganglia?
It is connected and configured to serve as a specialised action selection mechanism. It determines WHAT you do via a system of inhibition and disinhibition.
- What does Cn7 innervate?
- Special sensory innervation: anterior 2/3 of tongue - taste.
- Motor innervation: muscles of facial expression and stapedius.
- Parasympathetic innervation: submandibular and sublingual and lacrimal glands.
where are most of the axons of upper motor neurones?
lateral white matter of the spinal cord
What vein do the dural venous sinuses drain into?
The internal jugular veins.
Where do the internal carotid arteries enter the skull?
Through the carotid foramina.
where is the dorsal column-medial lemniscal system?
in the dorsal (posterior) white matter of the spinal cord
True or False; antibiotics can damage stereocilia.
True!
what is the function of broca’s area?
production of speech
What are the two fissures of the cerebellum called?
- The primary fissure.
- The horizontal fissure.
- What is the name of Cn3?
- Where does it exit the skull?
- Sensory, motor or both?
- Occulomotor.
- Superior orbital fissure.
- Motor and parasympathetic.
What region of the vertebral column has the greatest capacity for rotation?
The thoracic region.
What does the organ of corti sit on?
The basilar membrane.
Which dorsal column would an afferent signal from the upper limb use?
The cuneate fasciculus (lateral part of dorsal column). They then synapse at the cuneate nucleus of the medulla.
Give 3 types of glial cells in the CNS.
- Astrocytes.
- Oligodendrocytes.
- Microglia.
What nerve provides sensory innervation to the laryngopharynx?
Vagus - Cn 10.
Give 3 examples of neuromodulators. Do neuromodulators have short or long lasting effects?
- Dopamine, serotonin, noradrenaline.
- Long lasting effects.
An elderly patient presents with a stiff flexed arm, and a stiff extended leg (both on the left) which the patient finds difficult to bend. What is affected?
Upper motor neurone – this patient has had a stroke and so the UMN’s are affected.
Define synaptic transmission.
Integration/processing of information.
What would be the affect on the visual field if there was a lesion of the meyer’s (temporal) loop of the left optic radiation?
Right homonymous superior quadrantanopia. (Right upper quadrant of both eyes affected).
- What does Cn8 innervate?
- What are it’s functions?
- Innervation: cochlea and vestibular apparatus.
- Functions: hearing and proprioception of head and balance.
What are the signs of LMN weakness?
- Decreased muscle tone.
- Hypo-reflexia.
- Flaccid.
- Muscle atrophy.
- Fasciculations.
How do stapedius and tensor tympani change the stiffness of the ossicular chain?
They control the mobility of malleus and stapes and so protect the inner ear from loud noises.
What artery passes through foramen spinosum?
The middle meningeal artery.
What do the otolithic organs detect?
- Linear acceleration.
- Changes in head position relative to gravity.
what is the equivalent of a synaptic cleft at an electrical synapse?
gap junction
A man has presented with a history of weakness in both of his hands, he is now unable to open jars. Both of his hands show wasting in the Thenar eminence. He has developed slurred speech and difficultly swallowing over the past 3 weeks. His tongue appears spastic and he is unable to protrude it. What is the disease?
Motor neurone disease - both UMN and LMN are affected.
What is the filum terminale?
A fibrous strand that proceeds downwards from the apex of the conus medullaris.
How is the neural tube formed?
Notochord in mesoderm signals the ectoderm to form a thickened neural plate. Mitosis forms a neural groove. There are neural folds either side of the groove. These fuse at the midline forming the neural tube.
What is the relative refractory period?
It follows the absolute refractory period and is a time during which a 2nd stimulus that is stronger than the first is needed to produce another AP.
where does the rubrospinal tract originate?
the red nucleus
Where is the 4th ventricle formed in the embryo?
Rhombencephalon.
synaptic clefts are only found in which kind of synapses?
chemical synapses
Describe the spinothalamic pathway.
Nociceptors or thermoreceptors detect pain, temperature or crude touch. 1st order neurones carrying these signals enter the spinal cord and ascend 2-3 spinal levels before synapsing in the dorsal horn of grey matter. 2nd order neurones decussate either through the anterior or lateral tracts and then travel up to the thalamus where they synapse. 3rd order neurones travel through the internal capsule to the primary somatosensory cortex.
What structures makes up the lentiform nucleus?
- Putamen.
2. Globus pallidus.
What is the indirect pathway of the basal ganglia?
The indirect pathway is for when we want to inhibit movement. The motor cortex excites the striatum which inhibits the globus pallidus external meaning the subthalamic nucleus is no longer inhibited. The globus pallidus internal is therefore excited and the thalamus inhibited = reduced movement!
What descending pathways are described as pyramidal?
Corticospinal and corticobulbar tracts - responsible for voluntary control.
Where is the largest aggregation of choroid plexus?
In the lateral ventricles.
