anatomy: nervous system Flashcards
what are gyri
folds on the surface of the cerebral hemisphere
what are sulci
valleys which separate the gyri on the cerebral hemisphere’s surface
what separates the frontal and parietal lobes
central sulcus
where is the motor cortex and what does it do
in front of the central sulcus
controls the muscles of the opposite side of the body
where is the corresponding sensory gyrus and what does it do
behind the central sulcus
controls the muscles of the opposite side of the body
what colour are axons
white (because theyre covered in myelin)
grey matter: what happens here and what does it consist of
where all the processing takes place
consists mainly of neurone cell bodies
white matter: what happens here and what does it consist of
transmits the information from one place to another
consists of myelinated nerve fibres
the brain stem is predominantly which matter
white matter
CNS consists of
brain and spinal cord
PNS consists of
12 pairs of cranial nerves
31 pairs of spinal nerves
somatic nervous system
controls voluntary activities:
- motor (control of skeletal muscles)
- sensations (which reach conciousness)
autonomic nervous system
controls involuntary activities:
- motor (to glands, blood vessels, heart etc)
- sensory (blood pressure, co2 in blood etc)
autonomic nervous system is divided into
sympathetic (prepares body for emergencies)
parasympathetic (creates a state of rest and facilitates digestion)
what are the meninges
3 protective layers that lie between the skull ad the brain
function of the meninges
- to protect the brain
- to provide a framework for the blood supply
- to enclose the fluid filled subarachnoid space
3 meningeal layers
dura (inner surface of skull)
arachnoid (lies deep to the dura)
pia (adheres to the brain’s surface)
dura mater layers
periosteal layer (adherent to the inside of the skull) meningeal layer (stuck to the periosteal layer)
what is a venous sinus
where the periosteal and meningeal layers of the dura mater separate and the gap is filled with vebous blood
what gives the brain its “shiny” appearance
pia mater
3 potential spaces between the layers of the meninges
- outside the dura: epi-dural space/extradural space (doesnt exist in the absence of pathogens)
- between the dura and arachnoid: subdural space (doesnt exist in the absence of pathogens)
- between the arachnoid and pia mater: subarachnoid space (healthy- filled with cerebrospinal fluid (CSF)
what is the cerebrospinal fluid (CSF) and what does it do
clear fluid found in the subarachnoid space
- provides nutrients to the brain and helps maintain the balance of extracellular fluid
- protects the brain by providing a cushion against trauma
where is CSF made
choroid plexus (in the ventricles of the brain)
what are the 4 ventricles in the brain
- right and left lateral ventricles
- third ventricle
- fourth ventricle
where are the lateral ventricles
one on either side of the cerebral hemispheres
where is the third ventricle
in the midbrain
where is the fourth ventricle
lies behind the pons and medulla but in front of the cerebellum
where does CSF flow from and to
lateral ventricles → 3rd ventricle → cerebral aqueduct → fourth ventricle → subarachnoid space → venous sinuses and venous system
what is the Circle of Willis
the ring of blood vessels formed at the base of the brain by the 2 internal carotid arteries and 2 vertebral arteries
how many branches does the Circle of Willis have
6
what supplies the motor and sensory cortex with blood
middle cerebral artery
what are cranial nerves
nerves that arise directly from the substance of the brain
how many pairs of cranial nerves are there
12 pairs
I olfactory
sensory- smell
II optic
sensory- sight
III oculometer
motor- movement of eye,, autonomic to pupil and lens
IV trochlear
motor- movement of eye
V trigeminal
sensory- face, nose, oral cavity
motor- chewing muscles
VI abducens
motor- lateral (outward) movement of eye
VII facial
motor- facial expression
sensory- taste
autonomic- salivary glands
VIII vestibulocochlear
sensory- balance and hearing
IX glossopharyngeal
sensory- tongue and pharynx
autonomic- salivary glands
X vagus
autonomic motor- TO thoracic and abdominal organs
autonomic sensory- FROM thoracic and abdominal organs
XI accessory
motor- head, shoulders, pharynx, larynx and soft palate
XII hypoglossal
motor- tongue
clinical examination of I (olfactory nerve)
Test each nostril separately by asking the patient to close one nostril and smell different odours from small bottles
clinical examination of II (optic nerve)
Test visual acuity using a Snellen’s charts.
Test coloured vision using pseudo-isochromatic plates (eg Ishihara)
Test visual fields with either confrontation test or using a perimeter. The Red Pin test can also be used to outline the central field.
Ophthalmoscopy is essential to visualise the optic disc
clinical examination of III (oculomotor), IV (trochlear), VI (abducens)
These three nerves are tested together as they control the external ocular muscles responsible for ocular movements. Ask the patient to look at and follow your finger (each eye separately and both simultaneously) and make an ‘H’-shaped movement
clinical examination of V (trigeminal nerve)
Sensory: Test all sensory modalities at the three main branches (ophthalmic, maxillary, and Mandibular)
Motor: Test the temporal and masseter muscles by asking patient to clench their teeth
clinical examination of VII (facial nerve)
Ask patient to shut their eyes as tight as possible, then raise their eyebrows, then smile and whistle at you. Also taste sensation on the anterior 2/3 of the tongue
clinical examination of VIII (vestibulocochlear nerve)
Simply whisper in each ear and ask patient to repeat. Use a vibrating tuning fork to perform Rinne and Weber tests (will be explained to you by your demonstrator)
clinical examination of IX (glossopharyngeal nerve), X (vagus nerve)
Tickle back of pharynx - IX sensory branch, and note if reflex contraction occurs – X motor branch (palatal or ‘gag’ reflex)
clinical examination of XI (accessory nerve)
Test the function of the Trapezius muscle by asking patient to shrug their shoulders against resistance and of the Sternocleidomastoid muscle by asking patient to turn head on each side against resistance
clinical examination of XII (hypoglossal nerve)
Ask patient to put out the tongue as far as possible is it straight or deviated to one side?
nerve fibres entering the spinal cord
dorsal root fibres (sensory)
nerve fibres leaving the spinal cord
ventral root fibres (motor)
the ventral (motor) and dorsal (sensory) roots join together at the ?? to form a ??
intervertebral foramen to form a spinal nerve
what is the area from which the spinal cord emerges?
spinal cord segment
how many spinal nerves are there
31 pairs (so 31 segments)
the first seven spinal nerves pass through the foramina _______ the corresponding cervical vertebrae
ABOVE
the eighth and below spinal nerves pass through the foramina _______ the corresponding cervical vertebrae
BELOW
herniation of the inter-vertebral disc can do what?
- narrow the inter-vertebral foramen
- compress the nerve root
what causes sciatica?
compressed sciatic nerve at lumbar 5
what is a dermatome?
an area of skin which receives a sensory nerve supply form a single root of the spinal cord
what is a myotome?
a group of muscles supplied by the same spinal root
C5 myotome
elbow flexion
C7 myotome
elbow extension
L3 myotome
knee extension
L4 myotome
ankle dorsiflexion
S1 myotome
ankle plantarflexion
what does the autonomic nervous system control
heart/lungs/smooth muscle/glands (unconscious activity)
the parasympathetic ganglion will be where
close to the organ of innervation (target organ)
What are the frontal lobes
Primary motor cortex and prefrontal cortex
What are the temporal lobes? (4)
Primary auditory cortex, auditory association cortex (wernicke’s area), hippocampus and amygdala
What are the parietal lobes?
Primary somatosensory cortex and association cortex
What are the occipital lobes?
Primary visual and visual association cortex
what is the most posterior part of the frontal lobe
motor cortex
what is the most anterior part of the parietal lobe
somato-sensory cortex (important for sensation)
what joins the hindbrain and the cerebrum
the midbrain
what joins the 2 lobes of the cerebellum
vermis
what makes up the brainstem
midbrain, pons and medulla
What covers the insula
Frontal and temporal opercula
2 main fissures in the cerebellum?
horizontal and primary fissures
what information does the flocculo-nodular lobe deal with?
vestibular
what is the “worm like structure” in the centre of the cerebellum
vermis
what tract is linked to the superior cerebellar peduncle
spinocerebellar tract (sensory info for balance and position sense)
what tract is linked to the middle cerebellar peduncle
corticopontocerebellar (info from primary and motor cortex to spine)-motor planning
what is the largest and most lateral deep cerebellar nucleus
dentate nucleus
what is the inferior apex of the rhomboid fossa
obex
what is the posterior end of the corpus callosum called
spelium
what is the middle of the corpus callosum called
body
what is the anterior superior corpus callosum called
genu
what is the anterior inferior corpus callosum called
rostrum
the optic chiasm is at which side of the midbrain
anterior (rostral)
where is the primary visual cortex
in the walls of the calcarine sulcus
what is the white band in the primary visual cortex
striae of genari
anterior commisure
white matter fibres that connect the temporal lobes and olfactory structures on each side
septum pellucidum
2 thin vertical sheets made primarily of glia
where does the lamina terminalis go from and to
from rostrum of corpus callosum to anterior wall of 3rd ventricle
what joins the thalami of each side
interthalamic adhesion
what divides the diencephalon into the dorsal and ventral parts
hypothalamic sulcus
what does the medial geniculate body do
relays auditory info from midbrain to auditory cortex via the inferior brachium then inferior colliculi
what does the lateral geniculate body do
relays visual info from the optic nerve to both visual cortex via the optic radiation (vision) and superior brachium then superior colliculi (pupillary reflexes)
what connects the lateral and third ventricles
intraventricular foramen/ foramen of munroe (anterior)
what connects the lateral and fourth ventricles
cerebral aqueduct
how does the vertebral body exert force on the lower body
by sacroiliac joints
what is contained within the vertebral canal
spinal cord (and its coverings) and spinal nerves
