Neuro Flashcards
What are the first three embryological structures of the brain? What do they go on to form?
PROSENCEPHALON :
- Telencephalon: cerebral hemispheres
- Diencephalon: thalamus, hypothalamus
MESENCEPHALON:
= midbrain
RHOMBENCEPHALON:
- Metencephalon: cerebellum, pons
- Myelencephalon: medulla
What is the meaning of rostral and caudal?
rostral: towards brain
caudal: towards tail
Where do you find Broca’s area and Wernicke’s area?
Broca’s: frontal lobe
Wernicke’s: temporal lobe
What is the function of Broca’s area and Wernicke’s area? What are the difference between the two aphasias?
Broca’s: motor speech (forming sentences)
Wernicke’s: comprehension of speech (making sure what you’re say makes sense)
Broca’s aphasia: problem forming words
Wernicke’s aphasia: word formation is fine but speech makes no logical sense
What is the function of the frontal lobe?
contains motor cortex
social conduct
mood
language
What is the function of the parietal lobe?
proprioception
contains somatosensory cortex
What is the function of the temporal lobe?
auditory cortex
contains amygdala and hippocampus
What is the function of the occipital lobe?
primary visual cortex
What is the function of the amygdala?
feelings and emotion
What is the function of the hippocampus?
emotional memory
learning
What is the corpus callosum?
white matter bundle connecting the two hemispheres
What separates the two hemispheres?
deep longitudinal fissure
What fills the deep longitudinal fissure?
fold of dura mater called falx cerebri
What separates the cerebellum and occipital lobe?
tentorium cerebelli
What is contained within the grey and white matter?
Grey: neuronal cell bodies
White: glial cells + myelinated axons
What are the layers of the scalp from outermost to innermost?
Skin Connective Tissue Aponeurosis Loose connective tissue Periosteum
What is the name for the joins of the skull?
sutures
What is the name of the roof of the skull?
Calvarium
What layers make up the meninges from outermost to innermost?
Dura- Periosteal layer & Meningeal layer
Arachnoid
Pia
What makes the dura mater different from the other meningeal layers?
the dura mater has it’s own vascular supply
What is the blood supply to the dura?
middle meningeal artery
How is the dura innervated?
Innervated by CN5- Trigeminal
Where is the CSF found?
subarachnoid space
How is CSF reabsorbed?
arachnoid granulations
Describe the blood flow through the circle of willis?
blood enters via:
- vertebral arteries up through basilar artery
- internal carotid arteries
blood leaves via:
anterior, middle and posterior cerebral artery
What cells surround the capillaries in the brain?
neurons
endothelial cells
astrocytes
pericytes
What parts of the brain are supplied by each cerebral artery?
Anterior: front portion
Middle: sides of brain
Posterior: back portion
How will stroke in the anterior cerebral artery present?
loss of contralateral motion and sensory function in lower limbs
How will stroke in he middle cerebral artery present?
loss of contralateral motion and sensory function in upper limbs and face
+ Broca’s aphasia
How will stroke in the posterior cerebral artery present?
loss of vision
opposing side homonymous hemianopia with macular sparing
What is homonymous hemianopia?
a visual field defect involving either the two right or the two left halves of the visual fields of both eyes
What is macular sparing?
visual field loss that preserves vision in the center of the visual field
Describe the process of venous drainage.
- Choroid plexus makes CSF
- CSF fills 2 lateral ventricles
- Drains through foramen of Monroe
- Into 3rd ventricle
- Drains through cerebral aqueduct
- Into 4th ventricle
- Then drains into subarachnoid space, medially through foramen of magendie, laterally through foramen of luscka
- Reabsorbed by arachnoid granulations
List the sinuses in order.
superior + inferior sagittal sinus joined by falx cerebri join at the confluence of sinuses transverse sinus sigmoid sinus internal jugular vein
Name the structures in the cavernous sinus.
O: oculomotor nerve T: trochlea nerve O: opthalmic nerve M: maxillary nerve C: internal carotid artery A: abducens nerve
What cranial nerves have parasympathetic fibres?
1973
Name the cranial nerves in order.
I Olfactory II Optic III Oculomotor IV Trochlear V Trigeminal (V1= ophthalmic, V2= maxillary, V3= mandibular) VI Abducens VII Facial VIII Vestibulocochlear IX Glossopharyngeal X Vagus XI Accessory XII Hypoglossal
What cranial nerves leave the skull via the cribriform plate?
olfactory nerve
What cranial nerves leave the skull via the optic canal?
Optic nerve
What cranial nerves leave the skull via the superior orbital fissure?
Occulomotor
Trochlea
Trigeminal- V1
Abducens
What cranial nerves leave the skull via the foramen rotundum?
Trigeminal- V2
What cranial nerves leave the skull via the foramen ovale?
Trigeminal- V3
What cranial nerves leave the skull via the internal acoustic meatus?
Facial
Vestibulocochlear
What cranial nerves leave the skull via the jugular foramen?
glossopharyngeal
vagus
accessory
What cranial nerves leave the skull via the hypoglossal formamen?
hypoglossal
What is the function of the olfactory nerve?
smell
What is the function of the optic nerve?
vision
What is the function of the oculomotor nerve?
eye movement:
extra-ocular muscles EXCEPT LR6SO4 (lateral rectus and superior oblique)
What is the function of the trochlear nerve?
innervates superior oblique
What is the function of the trigeminal nerve?
V1: Ophthalmic
innervates upper face, eyelids, lacrimal glands, ethmoid sinus, corneal reflex
V2: Maxillary
maxillary portion of face
upper teeth and lips
nasopharynx
V3: Mandibular mandibular region of face anterior 2/3 tongue lower teeth and lips pinna of ear muscles of mastication tensor tympani tensor veli palatini mylohyoid
What is the function of the abducens nerve?
lateral rectus
What is the function of the facial nerve?
sensory impulses from the face
buccinator
platysma
What is the function of the vestibulocochlear nerve?
sound
balance
What is the function of the glossopharyngeal nerve?
pharynx, soft palate, pinna, posterior 1/3 tongue, carotid sinus, parotid gland, stylopharyngeus
What is the function of the vagus nerve?
aortic arch thoracic viscera larynx abdominal viscera pinna epiglottis soft palate pharynx GI tract
What is the function of the accessory nerve?
cranial: pharynx
spinal: sternocleidomastoid
What is the function of the hypoglossal nerve?
muscles of tongue
What are the two compartments of the eye?
aqueous body
vitreous body
What photoreceptors are found in the eye and what do they do?
rod- detect dim light
cones- colour vision
What makes up the outer eye?
Sclera- white of eye
Cornea- first point of refraction
Make makes up the middle eye?
Iris
Choroid
Ciliary Body
Lens
What makes up the inner eye?
Retina
Inner neural layer
What is found on the inner neural layer of the eye?
photoreceptors
light transducers
vitamin A storage
What makes up the ciliary body?
ciliary muscles
suspensory ligaments
What makes up the iris?
sphincter pupillae
dilator pupillae
What are the extra-ocular muscles and what do they each do?
Superior rectus- elevation medial rectus- adduction inferior rectus- depression lateral rectus- abduction inferior oblique- extorsion superior oblique- intorsion
What is palsy?
weakness or problems with muscles
How will a lesion on the oculomotor nerve affect the eye?
depression and abduction of the eye
eyelid drooped down
How will a lesion on the abducens nerve affect the eye?
can’t laterally rotate (abduct)
How will a lesion on the trochlear nerve affect the eye?
eye extorted, appears slightly elevated
How will a pituitary tumour affect the eyes?
bitemporal hemianopia
What is bitemporal hemianopia?
a type of partial blindness where vision is missing in the outer half of both the right and left visual field
What makes up the external ear?
Auricle
External acoustic meatus
Tympanic membrane
What is the function of the auricle?
directs sound to external acoustic meatus
What is the function of the external acoustic meatus?
transmits sound to tympanic membrane
contains cerumen- prevents pathogens and insects reaching eardrum
What makes up the middle ear?
ossicles (malleus, incus, stapes)
stapedius and tensor tympanic muscles
middle ear cavity (Eustachian tube and oval window)
What is the order of the ossicles in the ear from outermost to innermost?
malleus, incus, stapes
What is the function of the stapedius muscle?
dampens the stapes to prevent excess vibration in response to loud sound
What is the function of the tensor tympani muscle?
tenses tympanic membrane to prevent excessive vibrations and dampens loud sounds
What is the function of the Eustachian tube?
connects middle ear to nasopharynx and equalises pressure either side of tympanic membrane
empties middle ear secretions into nasopharynx
What is the function of the oval window?
transfers mechanical vibrations from middle ear into fluid filled vibrations in the inner ear
What makes up the inner ear?
semi-circular canals
vestibule
cochlea
organ of corti
What is the function of the semi-circular canals?
detects change in dynamic equilibrium (balance)
What is the function of the vestibule?
detects changes in static equilibrium
What makes up the vestibule?
two membranous sacs: utricle and saccule
What makes up the cochlea?
scala tympani
scala vestibuli
scala media
What is the function of the organ of corti?
has 3 rows of outer hair cells and 1 row of inner hair cells which have stereocilia which bend when hit with a vibration, this converts mechanical energy into electrical energy to be picked up but the auditory nerve
What is the sound pathway?
sound external acoustic meatus vibration of tympanic membrane vibration of ossicles oval window fluid-filled vibrations inside cochlea organ of corti basillar membrane hair cell depolarisation cochlear nerve vestibulocochlear nerve CNS
What are the 3 main pathways of the basal ganglia?
direct
indirect
nigrostriatal
What is the general function of the basal ganglia?
execution of smooth movements
What are the components of the basal ganglia?
putamen caudate nucleus thalamus external globus pallidus substantia nigra internal globus pallidus
What makes up the striatum?
caudate nucleus
globus pallidus
What makes up the lentiform nucleus?
globus pallidus
putamen
What are the type divisions of the substantia nigra?
pars reticularis (SNr) pars compacta (SNc)
What us the main physical difference between Parkinson’s and Huntington’s?
parkinsons- hypokinetic
huntingtons- hyperkinetic
What causes Parkinson’s?
loss of dopaminergic neurons in basal ganglia
can lead to overactivity of indirect pathway OR under activity of direct pathway
What causes Huntingtons?
destruction of indirect pathway of basal ganglia (degeneration of striatum)
What is the function of the ascending and descending spinal tracts?
ascending: send sensory information towards brain
descending: sends motor information towards muscles
How many orders of neuron are they for ascending and descending tracts?
ascending: 4 orders
descending: 2 orders
What are the ascending spinal tracts and what do they each do?
DCML (dorsal column-medial lemniscus): fine touch, proprioception, vibration
Spinothalamic: crude touch, pain, temperature
Spinocerebellar: unconscious proprioception
What are the two divisions of the DCML tract?
fasciculus cuneatus- upper limbs
fasciculus gracilis- lower limbs
What are the descending spinal tracts and what do they do?
PYRAMIDAL:
corticospinal: conscious muscle movement
corticobulbar: voluntary movement of face and neck muscles
4 EXTRA PYRAMIDAL: vestibulospinal reticulospinal rubrospinal tectospinal
Describe the pathway of the DCML spinal tract?
1st- dorsal root column, enters posterior column and ascends synapse to 2nd decussate at medulla synapse to 3rd in thalamus primary somatosensory cortex to 4th
What are the two divisions of the spinothalamic tract?
anterior: crude touch and pressure
lateral: pain and temperature
Describe the pathway of the spinothalamic tract.
- 1st- dorsal root ganglion
- enter spinal cord and ascend together ipsilaterally for 1-2 segments
- synapse- 2nd order decussate across anterior white commissure
- split into anterior and lateral tracts and ascend on contralateral spinal cord
- DOES NOT DECUSSATE AT MEDULLA
- synapse in thalamus to 3rd order, fibres travel to somatosensory cortex
- synapse to 4th order and carries messages to different parts of cortex
Describe the pathway of the spinocerebellar tract.
- 1st order- dorsal root ganglion into spinal cord
- synapse to 2nd order neuron: splits and EITHER crosses spinal cord and goes up ventral tract contralaterally OR doesn’t cross and ascends up the dorsal tract ipsilaterally
- dorsal tract into cerebellar peduncle
- both end up ipsilateral
What two types of neurons do we have in the descending tracts?
upper and lower motor neurons
What are the differences between the extrapyramidal descending tracts?
vestibulospinal + reticulospinal- do NOT decussate, ipsilateral innervation
rubrospinal+ tectospinal- DO decussate, contralateral innervation
What are the two divisions of the corticospinal tracts?
anterior and lateral
What proportion of corticospinal tracts decussate?
10% stay ipsilateral
90% decussate at medulla
What do the corticospinal and corticobulbar ascending tracts supply?
corticospinal: supplies musculature of body
corticobulbar: supplies musculature of head and neck
Where do neurons terminate in corticobulbar tract?
on motor nuclei of cranial nerves
What do the extrapyramidal tracts do?
rubrospinal: movement coordination
reticulospinal: posture adjustment especially during movement
vestibulospinal: posture and balance
tectospinal: movement in response to visual reflex
What is brown-sequard syndrome?
lesion of spinal cord
How does brown-sequard syndrome of the different tracts present?
corticospinal: ipsilateral paralysis
DCML: ipsilateral loss of fine touch, vibration and proprioception
spinothalamic: contralateral loss of pain, temp and crude touch
What is a motor unit?
an alpha motor neuron and extrafusal skeletal muscle fibres that it innervates
What do alpha motor neurons do?
controls muscle contraction for voluntary movement
What do gamma motor neurons do?
controls muscle contractions in response to external forces acting on muscles (stretch reflex for example)
How does the size of a motor unit correlate to its degree of control?
the smaller the unit, the finer the control
What is the most abundant muscle fibre and what innervates it?
extrafusal muscle
innervated by alpha motor neurons
What are intrafusal muscles? What innervates them?
regulatory unit surrounded by extrafusal fibres
innervated by gamma motor neurons
What is the function of intrafusal muscle fibres?
sense stretch- motors muscle length and rate of change
helps to prevents overstretching
these changes are detected by type 1a and type 2 sensory fibres
What is the stretch reflex?
when sensory neurons in an intrafusal unit detect overstretching
How does the stretch reflex work?
type 1a sensory fibres synapse with and excite alpha motor neurons from the same muscle and cause contraction of muscle to shorten length
type 2 sensory fibres synapse with and inhibit alpha motor neurons of the antagonistic muscle causing contraction
What are Golgi tendons?
tendons at the end of muscles that detect tension
have type 1b sensory fibres that are stimulated by the compression of muscle contraction and protects you from injuring yourself from too much tension
What is the inverse myotactic reflex?
inverse stretch reflex that protects from overload of muscle
if stimulated enough will cause inhibition/ relaxation of contracting muscle and stimulation of antagonistic muscle
What is resting potential? How is it established?
-70mV
established by Na+/K+ ATPase pump
Describe the permeability of axon membrane to Cl-, K+, Na+
membrane is semi-permeable
Cl- and K+ cross easily
Na+ crosses less readily
Why does myelination increase conduction along the axon?
electrical impulse jumps between nodes of ranvier (saltatory conduction)
What are the two refractory periods?
absolute refractory: no new action potentials can be generated
relative refractory: a new action potential may be generated if the stimulus is strong enough
What are the two types of synapse?
electrical
chemical
What is the most common type of synapse?
chemical
