Brain stem and diencephalon Flashcards
what are the 3 primary vesicles?
Prosencephalon; mesencephalon; rhombencephalon;
what are the 5 secondary vesicles? What structures do they give rise to?
Telencephalon (cerebrum); Diencephalon; mesencephalon; Metencephalon (Cerebellum and Pons); Myelencephalon (Medulla oblongata)
what structures does the Prosencephalon become>
Telencephalon; diencephalon;
what structures does the Mesencephalon become?
Mesencephalon;
what structures does the Rhombencephalon become?
Metencephalon; Myelencephalon
In the orientation of the brain what is anterior referred to? Posterior? Superior? Inferior?
Rostral; caudal; Dorsal; Ventral
the meynert axis is through what structures? Forel axis is through what structures?
Spinal cord; Cerebrum and diencephalon
the brainstem is located between? It is composed of what three structures?
Located between the diencephalon (interbrain) and spinal cord; Midbrain; Pons; Medulla oblongata
what ventricle is associated with the pons medulla and cerebellum?
4th ventricle
what are the ventricles in the cerebrum?
1st and 2nd (lateral) ventricles
what is the ventricle of the interbrain? What is the interbrain?
3rd ventricle
what is the ventricle of the midbrain?
aqueduct
what is the ventricle of the spinal cord?
central canal
the CSF flows form the ventricle to the subarachnoid space via three foramina located in what ventricle? What are the foramina called?
4th ventricle; There is one median called the Magendie; and two lateral called the Luschka foramina
what is the defining feature of the mesencephalon (posteriorly)?
superior and inferior colliculus
almost all cranial nerves arise from the? What nerves do not arise from this?
Brain Stem; Olfactory and Optic nerves
what are the three longitudinal substructures of the brainstem? From anterior to posterior
Base; Tegmentum; tectum
the base of the brainstem contains only?
Descending fibbers
what does the superior and inferior Colliculus are important in?
Superior colliculus: is important for reflex movement of the head towards stimulus (e.g. Light; noise etc.); Inferior colliculus: is a relay station for the auditory pathway
the tegmentum contains? (three things)
ALL Ascending pathways; ALL Nuclei of the cranial nerves; some descending pathways; prominent nuclei (reticular formation; red nucleus; substantia nigra)
the Base is composed of?
crus cerebri of the mid-brain; base of the pons; pyramids of the medulla
Crus cerebri contains?
Crus cerebri contains all descending pathways that originate from brain hemispheres (e.g. pyramidal tract
the major dopamine containing neurons in the brain are located in ?
the substantia nigra and VTA
the destruction of the substantia nigra is associated with disease?
Parkinson’s disease
the pons is wedged between what two structures? It release information to and from what?
midbrain and medulla; cerebellum and cerebrum/spinal cord
the pons maintains contact with the cerebellum through the?
Middle cerebellar peduncle
most nuclei of the cranial nerves are located in?
the pons
what cranial nerve emerges from the pons? What cranial nerves emerge at the border between the pons and medulla
Cranial nerve V (trigeminal); cranial nerves VI-VIII emerge at the border between the pons and medulla
the medulla contains what major structures? What does this structures contain?
Pyramid; contains the pyramidal tract
the reticular formation is located in the? It is made up of what four zones?
Tegmentum of midbrain pons and medulla; Midline zone (consists of the raphe nuclei); Medial Zone (Controls Motor activity); Lateral Zone(processes sensory information); intermediate field (Locus Coeruleus)
the major purpose of the reticular formation is to?
Regulate activity throughout the nervous system
Damage to the reticular formation or axons of the reticular activating system can result in?
States of altered consciousness: (Coma; Stupor; Vegetative State)
the locus coeruleus is located? Its axons project to? It modulates? And it is linked to?
Pons; axons project to all parts of the CNS; modulates pain; attention; and mood; is linked to depression; anxiety; and post-traumatic stress disorder
the Rapha nuclei are located? It is the largest collection of what type of neurons in the CNS? It modulates?
are located in the median part of the whole brainstem and are the largest collection of serotonergic neurons in the CNS; modulates pain; attention; and mood
what are the four tracts for unconscious movements? They make up?
Tectospinal tract; Rubrospinal tract; Reticulospinal tract; Vestibulospinal tract; The Extrapyramidal system
what are the two tracts for conscious movements? They make up?
corticospinal tract; cortico[bulbar]nuclear tract; Pyramidal system
the pyramidal system originates in? the Extrapyramidal System originates in?
Pyramidal system originates in the Cerebral cortex; the Extrapyramidal system originates in the Brain stem
At levels of brachial & lumbosacral plexuses; the à & gamma-motoneurons that supply the axial muscles are located in? whereas those that supply the limb muscles are located on the?
At levels of brachial & lumbosacral plexuses; the à& ?-motoneurons that supply the axial muscles are located in the medial part of the anterior horn referred to as the medial motoneurons pool; whereas those that supply the limb muscles are located on the lateral giving rise to the lateral motoneurons pool
All motor pathways are located either the?
lateral or ventral funiculi of the spinal cord
the lateral motor pathways feed into the? What two tracts make up this? They control what?
Feed into the lateral motoneurons pool; contains the lateral corticospinal tract and the rubrospinal tract; they control the fine voluntary movement of limb muscles and flexor-biased movement of upper limbs
the medial motor pathways feed into the? What four tracts make up this? They control what?
feed into the medial motoneuron pool; contains the anterior corticospinal tract; reticulospinal tract; vestibulospinal tract; tectospinal tract; controls postural & reflex movement of axial muscles
describe the general characteristics of the medial descending motor system?
mostly extrapyramidal tracts; is phylogenetically older than the lateral descending motor system; controls coordinated whole-body postural and orienting movements
describe the general characteristics of the lateral descending motor system?
is phylogenetically younger than all other descending motor tracts and highly developed in humans; is concerned with movements of the limbs (with more emphasis on distal limbs for fine movement)
where are the cell bodies of the upper motor neurons located? (two systems; two locations)
pyramidal tract (located in motor cortex of the brain); extrapyramidal tract(located in motor nuclei of the brainstem)
Spinal reflex’s involve? They are? And they do not require?
SPINAL REFLEXES: involve the spinal cord; are automated & stereotyped (predictable)reflexes; Do NOT require cortical input
supraspinal reflexes involve? They are? And they require?
SUPRASPINAL (POSTURAL) REFLEXES; involve spinal cord & supraspinal centres; are NOT stereotyped reflexes; instead they are flexible and goal-oriented (adaptive) reflexes; mostly coordinate their action with voluntary movements (goal oriented); hence require cortical input for coordination of their actions
the task of supraspinal reflexes is to?
to maintain equilibrium during ongoing voluntary movements (goal-oriented anticipatory reflex that is flexible and can improve after training; hence adaptive reflex); to regain equilibrium when it is disturbed (automated fast reflex that is less flexible)
where does the rubrospinal tract originate? Where does it decussate?
Rubrospinal tract originates in the red nucleus and decussates near its origin at midbrain level
The rubrospinal tract descends with what other tract? Where do they descend
The tract descends contralaterally and accompanies the lateral corticospinal tract (lateral motor pathway)
the rubrospinal tract innervates?
The tract innervates all flexor muscles of the upper limbs (“grabbing? behaviour)
the rubrospinal tract receives inputs from?
The rubrospinal tract gets input from the pyramidal system; Cell bodies of the rubrospinal tract are located in the red nucleus and receive inputs from motor cortex
what are the primary functions of the Reticulospinal tract?
It serves postural (upright position) & gait adjustments (balance) during movement (by acting on anti-gravity muscles; e.g. extensor muscles of the leg; hip; arm; and back (extensor-biased tract)); maintain body posture.
what are the two divisions of the Vestibulospinal tract? What are there functions?
Lateral vestibulospinal tract generates muscle tone (tonic active) in deep back & limb extensors in response to gravity (to maintain stance & balance); Medial vestibulospinal tract subserves selective and coordinated head and neck movements in response to sensory input from the vestibular system (mainly semicircular canals)
The tectospinal tract controls reflex movements of the?
The tectospinal tract controls reflex movements of the head; neck & upper limbs in response to all relevant sensory stimuli(visual; auditory; tactile; temperature; pain etc.)
describe the blood supply of the brain stem
Paravertebral arteries become the basilar artery; splits at the top of the brainstem to become the two posterior cerebral arteries
the diencephalon consists of ?
the diencephalon consists of the Thalamus; Hypothalamus; Epithalamus; Subthalamus; metathalamus and the 3rd ventricle
the thalamus is an important relay station for?
Thalamus is an important relay station for general sensation; special senses (except olfactory); and motor signals to the cerebral cortex. Partially; it also relays pathways of the limbic system
the hypothalamus plays a vital role in what?
Hypothalamus plays a vital role that includes various domains; e.g. it links nervous and endocrine system (the ?master gland?); modulates the autonomic nervous system; controls blood pressure; body temperature; hunger; thirst; and circadian rhythm. Briefly it maintains the homeostasis.
the Subthalamus is functionally part of? It plays a role in modulating?
Subthalamus functionally part of the basal ganglia and plays a role in modulating motor activity
What are the three parts of the Epithalamus?
Pineal body (involved in control of the circadian rhythm) ; Habitual (variety of functions); Stria medullaris ( contains fibre bundles to the habitual)
