Neuroanatomy (Assoc. Prof. Dorothy Oorschot) Flashcards
White matter largely consists of
Myelinated axons bundled into tracts
White matter tracts that extend vertically from brain to spinal cord forming the internal capsule are called
Projection tracts
White matter tracts that cross from one hemisphere to the other ?
Commisural tracts
Biggest commisural tract in the brain, wide band myelinated axons - around 300 million axons ?
Corpus callosum
Split brain is used to describe the transaction of the ?
Corpus callosum
Why is the corpus callosum transection done ?
It’s is a form of treatment in patients with severe and disabling EPILEPSY
Corpus callosum transection prevents
Spreading of ‘epileptic discharge’ from one hemisphere to the other.
Patients born without a corpus callosum
They are called Acallosal
Corpus callosum transections - certain problems ?
Not many , but for example - object in right hand with eyes closed, can be named ….. object in left hand can not be named.
Commisural tracts - type 2 called ?
Anterior commisure
Anterior commisure connects
Axons connect the middle and inferior temporal gyri of the two cerebral hemispheres
What does the association tract connect ?
Connects lobes and gyri within a single hemisphere
Name the three major tracts of white matter ?
Projection tracts, commisural tracts - 2, association tracts
What structures is the lentiform nucleas made of ?
Putamen (pod) and Globus pallidus ( pale globe)
What structures is the striatum made up from ?
Caudate nucleas and putamen
What structures is the corpus straitum made from ?
Caudate nucleas , putamen , globus pallidus ( pale globe )
The basal ganglia is formed from
The corpus striatum in association with subthalamic nuclei and substania nigra
The pallidum consists of ?
Globus pallidus - external and internal divisions
Amygadaloid nucleas is part of what system ?
This is not part of basal ganglia it is part of the limbic system
The internal capsule includes
PROJECTION, fibres to and from spinal cord
What gives the basal ganglia signals ?
Substantia nigra and motor cortex is where it receives input from and sends signals back to these regions.
Basal ganglia receives its instructions from ?
Substania nigra and motor cortex
Basal ganglia access to motor neurones is done through the ?
Thalamus , no direct access is available to the basal ganglia
Basal ganglia signalling to the motor cortex is done via which LOOP?
Cortical basal ganglia thalamic cortical loop
basal ganglia function 1
MOTOR CONTROL - inhibit unneccessary movement aka acts as a brake, so that we only have ordered exquisitive movement when needed.
what can over ride basal ganglia brake
cerebral cortex and substania nigra
basal ganglia function 2
regulating attention and cognition
basal ganglia at rest
inhibitory output from nucleas of basal ganglia, itgoes to inhibit neurons in the thalamus and these are excitatory, and they act on cortex neurons.
basal ganglia : when we want to move
motor cortex - excitatory neurons depolarise causing basal ganglia neurons to fire inhibitory - this inhibitory prevents the basal ganglia inhibitory neurons from firing , then firing back up to the motor cortex, this causes movement, via spinal cord to muscles
basal ganglia to spinal cord - direct or indirect ?
indirect
basal ganglia to cerebral cortex - direct or indirect ?
direct
name disorder of basal ganglia
parkisnsons disease
“oculomotor nerves’’ have somatic motor axons that go to the which four extrinsic eye muscles ?
inferior oblique muscle,
+ superior , inferior and medial rectus muscles - all 4 move ‘‘eyeball’’.
occulomotor nerves - somatic motor axons also goes to ? ( other then 4 others)
levator palpebrae superior muscle - “raises upper eyelid.’’
occulomotor nerves - parasympathetic ( autonomic ) motor axons control ?
- constrictor muscles of the iris - causing pupil to constrict and to the 2. ciliary muscle controlling the shape of the lens for visual focusing.
occulomotor nerves - sensory afferent carry ?
proprioceptor ( length of muscle)
information from eye muscles to midbrain.
what is the main function of the Oculomotor nerves ?
movement of each eye - eyelid, pupil constriction and focusing.
what does damage to occulomotor nerves do ?
causes drooping eyelid, dilated pupil, double vision, difficulty focusing and inability to move eye in certain directions.
where do the trochlea nerves emerge from ?
they emerge from the dorsal midbrain( only one to do so)
path of the trochlea nerves ?
dorsal midbrain then ventrally around the ‘midbrain’ and passes through the ‘superior orbital fissure’ to the ‘eye’.
what muscle do the trochlea nerves supply ?
the superior oblique muscle.
why is the trochlea nerve called that ?
it passes through a pulley aka trochlea.
what does the superior oblique muscle do ?
rotates the eye downward and laterally
what can damage to the trochlea nerves do ?
damage causes double vision and inability to rotate eye inferolaterally
what axons does the trochlea nerves supply ?
it supplies somatic motor axons and carries proprioceptors from the superior oblique muscle.
cranial nerve number 5 = ?
trigeminal nerves ( three branches)
what are the three trigeminal nerves branches ?
opthalamic division ( v1) , maxillary division (v2) and mandibullar division (v3)
trigeminal nerves actions ? + locations eg sensory etc
sensory axons extends from face to pons and pons to muscles
the cells bodies of the sensory neurons of the trigeminal nerves is located ?
in the large trigeminal ganglion
trigeminal nerves : where do the nerves run for the opthalamic division ? and what does it convey ?
axons run from face to pons via superior orbital fissure
convey sensory impulses from skin of anterior scalp, upper eyelid and nose and from nasal cavity mucosa cornea and lacrimal ( tear ) gland.
Trigeminal nerves : maxillary division - where do the nerves run and what do they convey ?
axons run from the face to pons via foramen rotundum
they convey sensory impulses from the nasal cavity mucosa, palate, upper teeth, skin of cheek and upper lip.
trigeminal nerves : mandibular division - where do the nerves run and what do they convey ?
axons pass through the skull via foramen ovale
they convey sensory impulses from anterior tongue ( except taste buds ) , lower teeth, skin of chin, and temporal region of scalp.
+ motor branch - different card
trigeminal nerves : mandibular division - where do the nerves run and what do they convey ? - 2
axons motor to proprioceptor axons from muscles of mastication.
what is the largest cranial nerves ?
trigeminal nerves
which nerves supply motor axons to muscles of chewing ( mastication ) ?
trigeminal nerves
what does damage to trigeminal nerves lead to ?
damage produces loss of sensation and impaired chewing.
which nerves are anaesthetised during dental procedures ?
trigeminal nerves
what is an inflammation of the trigeminal nerves called ? and where does it happen ? and why does it happen ? anbd treatment ?
Tic Douloureux ( -tic - dolaroo) aka trigeminal Neuralgia, usually at the root, right next to where it emerges from the pons due to PRESSURE on the nerve root
treatment :: usually they will cut the nerve/ severe it to cause pain relieve or analgesics
abducens nerve : pathway ?
axons leave inferior pons and pass through superior orbital fissure to eye ( lateral rectus muscle)
what is the functions of the abducens nerves ?
provide eye movements ( abducts the eye ball ).
what happens when abducens nerves are damaged ?
damages results in inability to rotate eye laterally and at rest rotates eye medially (lazy eye )
facial nerves : pathway ?
axons emerge from pons enter temporal bone via internal auditory meatus and run within bone through inner ear cavity before emerging through stylomastoid foramen to course to the lateral aspect of the face
how many branches do the facial nerves have and what are they called ?
5 - temporal, zygomatic, buccal , mandibular and cervical.
facial nerves mainly sensory or motor ?
they are mainly motor
motor axons supply of facial nerves ?
supply motor axons to skeletal muscle of face - mainly muscles of facial expression not chewing.
2 motor supply types of the facial nerves ?
parasympathetic ( autonomic ) motor impulses to lacrimal ( tear ) glands, nasal and salivary glands & convey sensory impulses from taste buds of anterior 2/3 of tongue.
damage to the facial nerves leads to ?
sagging facial muscles and disturbed sense of taste ( missing sweet, salty and umami )
facial nerves : bell’s palsy ? what is it
paralysis of facial muscles ( unilateral) and patial loss of taste sensation
what is the cause of bells palsy ?
viral infection - causing inflammation of the facial nerve
what are the symptoms of bells palsy
lower eyelid droops, corner of mouth sags, tears drip continously, eye cannot be completely, paralysed face is pulled
what is the treatment of balls palsy ?
steroids and rest
vestibulocochlear nerves - emerging from ?
axons arising from hearing and equilibrium apparatus within inner ear of temporal bone, passing through internal acoustic meatus to enter brainstem at the pons medulla border
what do the vestibulocochlear nerves mainly do sensory or motor ?
they are PURELY sensory
what is the function of the vestibulocochlear nerves ?
they provide hearing ( cochlea nerves ) and sense of balance ( vestibular nerves )
what can damage to the vestibulocochlear nerves do ?
the damage produces deafness, dizziness, nausea, loss of balance and NYSTAGMUS = rapid involuntary eye movements.
describe auditory pathway ?
stimulation of inner hair cells, leading to cochlear nucleas stimulation then the superior olivary nucleas is stimulated thern those neurons send action potential forward to the inferior colliculus and then they go to the medial geniculate body of the thalamus and then they convey out to the primary auditory cortex aka transverse temporal gyrus
where do the glossopharyngeal nerves emerge from ?
axons emerge from the medulla and leave skull through jugular foramen.
describe the motor supply of the glossopharyngeal nerves ??
supply motor axons to carry proprioceptor fibres from a pharyngeal muscle called stylophargygeus.
and supplies parasympthathetic motor axons to parotid salivary gland. ( to put saliva into mouth .
describe the sensory axons of the glossopharyngeal nerves ?
sensory axons conducts taste and general sensory impulses from pharynx and posterior 1/3 of tongue.
& sensory impulses from chemoreceptors in the carotid body and pressure receptors of carotid sinus.
functions of the Glossopharngeal nerves ?
provide control over swallowing, salivation, gagging sensations from posterior 1/3 of tongue, control of blood pressure and respiration
what can damage of glossopharyngeal nerves lead to ?
damage results in loss of bitter and sour taste and impaired swallowing
where does the vagus nerve emerge from ?
axons emerge from medulla and pass through via jugular foramen, descend through neck region into thorax and abdomen.
are vagus nerves mixed nerves ?
yes they are motor and sensory nerves
sensory side of vagus nerves ? card 1 - as cannot fit all
they supply motor axons to carry proprioceptor fibres from skeletal muscles of pharynx and larynx + parasympathetic motor fibres supply heart, lungs and abdomibnal viscera.
sensory side of vagus nerves ? card 2 - as cannot fit all
transmitting sensory impulses from chemoreceptors in the carotid and aortic bodies and pressure receptors of the carotid sinus.
sensory side of vagus nerves ? card 3 - as cannot fit all
conducting sensory impulses from taste buds of posterior tongue and pharynx
motor supply of vagus nerves ?
it supplies motor axons to carry proprioceptor fibres from skeletal muscle of pharynx and larynx and parasympathetic motor fibres supply heart, lungs and abdominal viscera.
which cranial nerves extends past the head and neck to the thorax and abdomen ?
vagus nerves
in the vagus nerves are majority of the motor axons sympathetic or parasympathetic ?
parasympathetic
functions of vagus nerve
swallowing and speech and regulation of activities of major viscera
what can damage of the vagus nerve do ?
damage causes hoarseness or loss of voice, impaired swallowing and digestive system mobility.
what happens if u cut vagus nerves
death - as it keeps heart going and breathing etc.
accesory nerve - where does it emerge from ?
from a cranial root ( lateral medulla ) — goes through jugular foraman and joins vagus nerve and a spinal root ( spinal C1 - C5 ) — up through jugular foramen and joins neck muscles.
accessory nerves - cranial root what does the motor part supply ?
it joins the vagus nerve to supply motor axons to larynx, pharynx and soft palate
accessory nerves - spinal root what does the motor axons supply ?
supplies motor axons to trapezius and sternocleidomastoid muscles and therefore provides head, neck and shoulder movement.
accessory nerves - damage to the cranial root ?
damage causes hoarseness or loss of voice and impaired swallowing
accessory nerves - damage to the spinal root ?
impaired head neck and shoulder movement — unable to shrug on one side if unilateral injury
hypoglossal nerve : where do the axons emerge from ?
axons arise by a series of roots from medulla and exit from skull via hypoglossal canal to tongue. AXONs EMERGE between the pyramid and olive
motor supply of hypoglossal nerves ?
supply somatic motor axons to intrinsic and extrinsic muscles of the tongue
what is the function of the hypoglossal nerves ?
provide tongue movements of speech, food manipulation and swallowing.
what happens when you damage the hyppoglossal nerves ?
damage will cause difficulty in speech and swallowing and on both sides an inability to protude tongue and on one side tongue deviates towards injured side and results in ipsilateral atrophy eventually.
