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’.