Revision cards Flashcards
What produces myelin in the CNS?
Oligodendrocytes
What produces myelin in the PNS?
Schwann cells
What makes up the PNS?
31 pairs of spinal nerves and 12 pairs of cranial nerves.
What type of neurones make up the majority of the nervous system?
Multipolar neurones
Describe dendrites in relation to the cell body?
Dendrites carry info towards the cell body.
Describe axons in relation to the cell body?
Axons carry information away from the cell body.
What is the difference between oligodendrocytes and Schwann cells?
Oligodendrocytes can wrap multiple axons in myelin whereas schwann cells can only wrap one.
Function of microglia
Immune monitoring and antigen presentation in the CNS
Function of ependymal cells
Line the ventricles- ciliated columnar/cuboidal epithelium.
What type of astrocytes are found largely in white matter?
Fibrous astrocyte.
What is a fissure?
A fold that is deeper than a sulcus.
Which type of matter is on the outside of the brain?
Grey matter
What does grey matter contain?
Neurones, cell processes, synapses and support cells
What does white matter contain?
Myelinated fibres.
Where does the frontal lobe lie?
Anterior to central sulcus
Superior to lateral sulcus
Where does the parietal lobe lie?
Posterior to the central sulcus
Superior to the lateral sulcus
Anterior to the parietal-occipital sulcus
Where does the occipital lobe lie?
Posterior to the parietal occipital sulcus.
Where does the temporal lobe lie?
Inferior to the lateral sulcus.
What is the 5th lobe called? Where is it hidden?
Insular lobe- 5th lobe
Hidden in the lateral fissure.
What are the three layers of the meninges called?
Dura mater
Arachnoid mater
Pia mater.
What plexus’s does the enteric nervous system have? Where are they located?
Has a myenteric plexus (between outer layers of smooth muscle) and submucosal plexus (in the submucosa)
What drains into the internal jugular vein?
Dural venous sinuses.
What are dural venous sinuses?
Where the blood from the brain drains to.
What is a collection of cell bodies in the PNS called?
Ganglia
What is a collection of cell bodies in the CNS called?
Nucleus
What is a multipolar neurone?
2 or more dendrites. It has its cell body in the CNS.
What is a unipolar neurone?
Double process. Has cell body in PNS.
What is a nerve?
What is the name for this in the CNS?
A collection of axons surrounded by connective tissue and blood vessels.
A tract.
Where are spinal nerves found?
ONLY found in intervertebral foramina.
What does each spinal nerve supply a body segment with?
General sensory
Somatic motor to skeletal muscles
Sympathetic nerve supply to the skin and smooth muscle of arterioles.
What is a dermatome?
An area of skin supplied with sensory innervation from one spinal nerve.
What is a myotome?
The skeletal muscles supplied by a single spinal nerve.
On a dermatomal map, where is the male nipple?
T4.
On a dermatomal map, where is the umbilicus?
T10.
Where do sympathetics flow out of the spina cord from?
T1-L2.
Which nerves contain parasympathetics?
10,9,7 and 3.
What are the four options for parasympathetic nerves to travel via (not the nerves themselves e.g. CN X)?
Via ciliary ganglion- to the eye
Parasympathetic ganglia in the head- lacrimal gland and salivary gland.
Via vagus nerve- to the abdominal organs as far as the midgut, neck and chest.
Sacral spinal nerves- hindgut and perineum.
What anchors the spinal cord in the canal?
What is it made from?
The denticulate ligament.
Made from arachnoid and Pia mater anchoring it to the dura at various points.
What is the end of the spinal cord termed?
Conus medullaris
What is the continuation of the spinal cord to the dorsum of the coccyx called?
Filum terminale.
Describe the distribution of matter in the spinal cord?
Grey matter- inside
White matter- outside.
What does the central canal open into in the head?
The 4th ventricle.
What is the arterial supply to the spinal cord?
Longitudinal arteries- 2 posterior and one anterior. Originating from vertebral arteries.
Radicular arteries- travel along dorsal and ventral roots.
Segmental arteries- from intercostal, vertebral and lumbar arteries.
What is the venous drainage of the spinal cord?
By longitudinal and segmental veins.
Where exactly is the epidural space?
In between the dura mater and periosteum in the spinal canal. This space doesn’t exist in the cranial cavity because the dura is adhesive to the periosteum.
Where is the primary somatosensory cortex?
Postcentral gyrus (parietal lobe).
Where does the cerebellum sit?
In the posterior cranial fossa, subtentorium (below the tentorium cerebelli).
Describe the matter distribution of the cerebellum?
White matter core with grey matter outside.
How does the cerebellum attach to the brainstem?
Via three stalks called peduncles.
Middle, inferior and superior cerebellar peduncles.
What is the middle region of the cerebellum called?
The vermis.
What are the three layers of the cerebellum- from superficial to deep?
Molecular cell layer
Purkinje cell layer
Granule cell layer.
Where in the cerebellum does proprioceptive information arrive and from here where is it transmitted?
Arrives in the granular cell layer which is then communicated to the purkinje cell layer (which then sends info to the deep cerebellar nuclei) and the molecular cell layer.
Where will the afferents that arrive in the cerebellum come from?
Spinal cord- containing somatic proprioreceptors and pressure receptors
Cerebral cortex - brain needs to tell the cerebellum what its doing.
Vestibular apparatus- tells about balance
How do afferents enter the cerebellum?
Via the cerebellar peduncles and project mainly into the granular cell layer.
How is information output from the cerebellum?
Only output is via the purkinje cells which mainly communicate with the deep cerebellar nuclie.
Axons exiting the cerebellum will synapse where?
They synapse in the medulla after decussation.
Cerebellar lesions influence the ipsilateral or contralateral side of the body?
Ipsilateral (on the same side)
If there is a unilateral hemispheric lesion in the cerebellum, what signs might show?
Disturbance of co-ordination in limbs.
Intention tremor
Unsteady gait
If there is bilateral hemispheric lesions in the cerebellum, what signs are likely to show?
Slowed, slurred speech.
Bilateral inco-ordination of the arms
Cerebellar ataxia (staggering, wide based gait).
If there is a midline lesion in the cerebellum, what signs are likely to show?
Disturbance of postural control. Patient will tend to fall over when standing or sitting despite preserved limb co-ordination.
What is the function of the basal ganglia?
To facilitate purposeful movement
To inhibit unwanted movement.
Role in posture and muscle tone.
Name the five basal ganglia?
Caudate nucleus Putamen Globus pallidus Subthalamic nucleus Substantia nigra.
What makes up the striatum?
Caudate nucleus and putamen.
What makes up the corpus striatum?
Caudate nucleus, putamen and globus pallidus.
What makes up the lenticular nucleus?
Putamen and globus pallidus.
Would a lesion in the basal ganglia lead to contralateral or ipsilateral signs?
Contralateral (in the brain so will cross over).
What signs may lesions in the basal ganglia cause?
Changes in muscle tone
Dyskinesia’s- abnormal unwanted muscle movement
These include tremor, chorea (rapid, asymmetrical movements usually affecting distal limbs), myoclonus (muscle jerks)
What does Huntington’s disease cause?
Progressive degeneration of the basal ganglia and cortex.
What signs might someone with Huntington’s disease have?
Chorea
Progressive dementia
What ocular muscles does the oculomotor nerve supply?
Damage to the oculomotor nuclei will cause what signs?
Supplies superior rectus, inferior and medial rectus and inferior oblique muscle.
Therefore damage to this nuclei will cause the eye to move out (the lateral rectus is still working whereas the medial one has stopped) and out (the superior oblique is still working but the inferior oblique has stopped).
According to the brainstem rules of 4, what are the 4 medial structures in the brainstem?
All begin with 'M' Motor pathway- corticospinal tract Medial lemiscal pathway- dorsal column Medial longitudinal fasciculus- connections between cranial nerves in charge of eye movements resulting in internuclear ophthalmoplegia. Motor nuclei- of 3,4,6 and 12.
According to the brainstem rules of 4, what are the 4 lateral (side) structures in the brainstem?
Spinocerebellar pathway
Spinothalamic pathway
Sensory nucleus of the 5th cranial nerve
Sympathetic pathway.
In regards to the 4 lateral structures of the brainstem
For each of them, describe the resulting possible deficit if they were to become damaged?
Spinocerebellar pathway- ipsilateral ataxia of the arm and leg.
Spinothalamic- contralateral alteration in pain and temp sensation in the arm and leg
Sensory nucleus of the 5th cranial nuclei- ipsilateral alteration in pain and temp over the distribtion of the 5th cranial nerve
Sympathetic- ipsilateral horners syndrome.
What is the function of the Edinger Westphal nucleus?
Source of parasympathetics to the eye.
Where do fibres from the Edinger Westphal nucleus travel within?
The IIIrd nerve.
What does the trochlear nerve supply?
Superior oblique muscle of the eye.
Why is the trochlear nucleus unique?
Exits the brainstem dorsally
Crosses over in the roof of the fourth ventricle.
What does the trigeminal nerve supply?
Pain and temp sensation to the face. Also mouth sensation.
Motor to the muscles of mastication.
What are the four types of nuclei that make up the trigeminal nerve nuclei?
Motor-in the midline of the pons
Sensory- just lateral to the motor
Spinal nucleus- carries pain fibres
Mesencephalic nucleus- thin ribbon of cells that run along the fourth ventricle
What are the four types of nuclei that make up the trigeminal nerve nuclei?
Motor-in the midline of the pons
Sensory- just lateral to the motor
Spinal nucleus- carries pain fibres and temp.
Mesencephalic nucleus- thin ribbon of cells that run along the fourth ventricle. Offers proprioceptive info from muscles of mastication.
Where is the abducent cranial nerve nuclei located?
In the pons midline.
What does the facial nerve supply?
Innervates muscles of facial expression
Carries special sensory of taste from the anterior 2/3rds of the tongue.
Parasympathetics to the salivary glands.
What carries the taste from the posterior 1/3rd of the tongue?
Glossopharyngeal.
Where do taste fibres go?
To the solitary nucleus.
What does the vestibulocochlear nerve supply?
Semicircular canals and the cochlear.
What does the glossopharyngeal nerve supply?
Taste to posterior 1/3rd of tongue
Motor to muscles of the pharynx.
Where do taste fibres in the glossopharyngeal nerve go?
To the solitary nucleus.
Where do motor fibres in the glossopharyngeal nerve go?
Nucleus ambiguous.
Where does the spinal accessory nerve originate?
Cervical spinal cord.
Where do motor fibres in the vagus nerve go?
Nucleus ambiguous
What is the function of the dorsal nucleus?
Vagus nerve sends secretomotor parasympathetic fibres from here.
What does the hypoglossal nerve innervate?
Muscles of the tongue.
Where is the hypoglossal nuclei located?
Midline in the medulla.
Which cranial nerves share the superior and inferior salvitatory nuclei?
CN VII and IX.
it has axons with parasympathetics to the salivary glands and pterygopalantine ganglion
Which cranial nerves share the solitary nucleus?
CN VII, CN IX and CN X.
Which cranial nerves share the nucleus ambiguous?
CN IX and X
(also cranial part of spinal accessory).
What are the 5 layers of the scalp?
S- skin C-connective tissue A- aponeurosis L- loose connective tissue P- pericranium
Why do scalp lacerations and incisions bleed excessively?
Their are several anastomoses in the scalp just deep to the skin.
What is important about the pterion?
Thinnest part of the skull.
Which four bones make up the pterion?
Parietal, frontal, sphenoid and temporal.
What artery courses over the deep aspect of the pterion?
Middle meningeal artery.
Name the layers of the meninges from superficial to deep.
Dura mater
Arachnoid mater
Pia mater.
Which meningeal layer reabsorbs CSF?
Arachnoid granulations in the arachnoid mater.
What is the tentorium cerebelli?
A tough sheet of dura mater that ‘tents’ over the cerebellum.
Where does the tentorium cerebelli attach?
To the ridges on the petrous part of the temporal bone.
What is the diaphragm cerebelli?
A tough sheet of dura mater that tents over the pituitary fossa.
What is the falx cerebri?
Where does it attach?
A midline structure made of dura mater.
Attaches anteriorly to the crista Galli of the ethmoid bone. Attaches to the internal occipital protuberance posteriorly.
What is the function of the falx cerebri?
Separates right and left hemispheres.
What is dangerous about having trauma to the danger triangle on the face?
If you damage any of the facial veins, it can allow bacteria to spread back into the cavernous sinus (the facial veins drain here).
What is different about facial veins in comparison with other veins in the body?
They don’t have valves so therefore can have potential back flow. They are also thick walled- so if they puncture they remain patent allowing bacteria in.
Where is the subarachnoid space?
Between arachnoid mater and Pia mater.
How many mls a day of CSF circulates?
400-500mls.
What produces CSF?
Choroid plexus of the ventricles.
Where is CSF reabsorbed?
Dural venous sinus’s via the arachnoid granulations.
Where can the subarachnoid space be accessed?
Lumbar puncture at L3/4 or L4/5.
Where does the subarachnoid space end?
S2.
Describe the circulation of CSF including how its produced and how its reabsorbed?
Produced by the choroid plexus in the lateral ventricles. Flows through lateral ventricles and down through the interventricular foramen (foramen of Monroe). It goes down into the 3rd ventricle where more CSF is added. It then flows down to the 4th ventricle via the cerebral aqueduct. It then flows mainly into the subarachnoid space but also into the central canal.
What is hydrocephalus?
Increased CSF. Could be due to excessive production, obstruction of flow or inadequate reabsorption.
Where is an extradural haemorrhage?
Where is this likely to have come from?
Between the dura and the bone.
The middle meningeal artery.
What can cause a ruptured middle meningeal artery?
Trauma to the pterion.
Where is a subdural haemorrhage?
What vessel is likely to cause this?
Between the dura and the arachnoid mater.
The cerebral veins tearing.
Who is likely to get a tear in their cerebral vein?
A fall in the elderly or an alcoholic.
Where is a subarachnoid haemorrhage?
What vessel is likely to cause this?
Between the arachnoid mater and Pia mater, into the CSF.
Rupture in the circle of willis- berry aneurysm.
What layers does the needle have to go through for epidural anaesthesia?
Skin Superficial fascia Supraspinatous ligament Interspinatous ligament Ligamentum flavum Epidural space.
What can cause an epidural haematoma and what are the consequences of this?
Epidural haematoma- when you damage the extradural venous plexi during insertion of the catheter.
Can cause compression on the spinal cord.
What further layers does the needle go through in lumbar puncture than in epidural anaesthesia?
Goes through the dura mater, arachnoid mater into the subarachnoid space.
Where is the needle most safely inserted too in epidural anaesthesia?
Where it is next to cauda equina rather than spinal cord (below L2), the vertebrae are not fused (so not in the sacrum)- meaning L3/4 area.
What can compression of the ocular nerve in herniation cause?
Fixed dilated pupil.
Name the types of supratentorial herniations?
Subfalcine (cingulate)- below the falx cerebri
Central
Uncul- the uncus (medial part of temporal lobe herniates below the tentorium cerebelli.
Transcalvarial
Name the two types of infratentorial herniation?
Upward- cerebellum goes through the tentorium cerebelli.
Downward or tonsillar herniation- the cerebellar tonsils herniate into the foramen magnum.
Where is the primary auditory cortex found?
Just above the lateral sulcus in the temporal lobe.
Where do fibres carrying information regarding low frequency sound end up in the primary auditory cortex?
Anterolateral.
Where do fibres carrying information regarding high frequency sound end up in the primary auditory cortex?
Posteromedial.
What is aphasia?
Inability to use language.
If there is damage to Broca’s area, what will patients have difficulty doing?
what is it called?
Have difficulty in producing language. Often only say the most important words in a sentence however can comprehend language.
Broca’s, motor or defective aphasia.
If there is damage to Wernicke’s area, what will patients have?
What is it called?
Patients will have difficulty comprehending language.
Wernicke’s, sensory or receptive aphasia.
What does your body use to maintain an upright position?
Eyesight
Vestibular apparatus
Proprioception.
Which nuclei form connections with the vestibular nuclei to maintain balance?
CN III, IV and VI.
NOTE-
no specific area of the brain responsible for dealing with vestibular information. Three areas known to play a role are- posterior insular cortex, an area just rostral to the primary auditory cortex, an area of the parietal cortex.
The lower visual field is projected to what area of the gyrus?
Superior to the calcarine sulcus.
The upper visual field is projected to what area of the gyrus?
Inferior to the calcarine sulcus.
What is another word for optic radiations?
Geniculocalcarine tract.
What is Meyers loop?
A pair of optic radiations loop round the temporal part of the lateral ventricle before coming to the visual cortex.
Which area of the brain controls eye movements?
What is each of these areas roles?
Visual cortex and the frontal eye fields.
The visual cortex provides movements in response to stimuli. These will be smooth.
The frontal cortex controls movements on command (not in response to visual stimuli). These will be jumpy.
what is the role of association fibres?
Connect cortical sites lying in the same hemisphere. (connection between two different parts of the hemisphere).
what is the role of commissural fibres?
Connect one hemisphere to the other- usually connecting areas of similar function.
What is the role of projection fibres?
Connect hemispheres to deeper structures including the thalamus, striatum, brain stem and spinal cord.
