CM- Intro to CNS Flashcards
Why sulcus divides the frontal and parietal lobes of the brain?
What gyrus is found just anterior and posterior to the sulcus?
The central sulcus divides frontal and parietal lobes.
Frontal lobe- primary motor cortex [causes movement of contralateral body]
Parietal lobe- primary somatosensory cortex [receives senses from contralateral body]
In what hemisphere of the brain can the following be found:
- primary motor cortex
- primary somatosensory cortex
- primary auditory cortex
- primary visual cortex?
- frontal [just in front of central sulcus]
- parietal [just behind central sulcus]
- temporal [just below sylvian fissure]
- occipital
These are on both sides of the brain
What is the location and function of Broca’s area and Wernicke’s area?
Broca’s is on the left inferior frontal gyrus and controls the motor function of speech.
Wernicke’s is on the left posterior superior temporal gyrus and controls speech comprehension
What are the forebrain components of the basal ganglia?
- caudate
- putamen
- globus pallidus
What is the purpose of the internal capsule?
It is white matter that contains axons from cerebral hemispheres to targets in the brainstem and spinal cord [corticospinal fibers]
The fibers form the cerebral peduncles of the midbrain [on the brainstem]
What brain structures are responsible for the motor system [planning, initiation, cessation of movement]?
Forebrain:
- caudate
- putamen
- globus pallidus
Diencephalon:
1. subthalamic nuclei [STN]
Midbrain
1. Substantia nigra
A person has lesions in the central white matter and corpus collosum. What is your first reaction?
- MS
2. leukodystrophies
At autopsy, a patient has atrophied caudate and putamen. What is this a prominent feature of?
Huntington’s disease
The hippocampus is located on the ____________________________ and plays a critical role in _______________________.
It is usually one of the first areas to be damaged in what 2 situations?
It is on the medial aspect of the temporal lobe and plays a role in the formation of memory/learning.
It is one of the first areas to be injured in Alzheimer’s and generalized ischemic injury
What portion of the brain is supplied by the:
- anterior cerebral artery (ACA)
- middle cerebral artery {MCA}
- posterior cerebral artery {PCA}
- medial aspects of each hemisphere
- lateral aspect of each hemisphere
- occipital cortex, inferior parieto-temporal cortex
What is the portion of the brain that lies between the cerebrum and the brainstem?
What 4 components make up this area?
Diencephalon lies between the cerebrum and the brainstem.
- thalamus
- hypothalamus
- epithalamus [pineal gland]
- subthalamus
What are the 3 major functions of the thalamus?
What nuclei correlate with each function?
- Sensory
- ventral posterior [somatosensory]
- lateral geniculate [visual]
- medial geniculate [auditory] - Motor
- ventral anterior
- ventral lateral - limbic and cognitive function
- anterior thalamic
- pulvinar nucleus
What is the role of the hypothalamus?
- regulate homeostasis by:
- temp regulation
- food and water intake
- endocrine function [metabolism]
- memory - send trophic hormones to the ant. pituitary to regulate hormone release
What is the role of the pineal gland?
It is a source of melatonin and regulates circadian rhythm
What is the role of the subthalamus?
What happens if it is damaged?
It is the diencephalon component of the basal ganglia. [STN is in the “indirect” movement pathway].
If the subthalamus is damaged, it will result in hemiballism [involuntary flinging movements of contralateral limb]
What are the major landmarks of the midbrain of the brainstem?
- cerebral peduncles
- superior colliculi
- inferior colliculi
- red nucleus
- substantia nigra
- ascending sensory axons
- posterior commisure
- cranial nerve nuclei
What axons travel through the cerebral penduncles of the midbrain?
What axons travel through the ascending sensory axons?
Cerebral peduncles:
1. axons to the brainstem
2. corticospinal axons to the spinal cord
[separated by interpeduncular fossa]
Ascending sensory:
1. medial leminiscus
2. anterolateral pathway
[located in the tegmentum]
What is the purpose of the substantia nigra and raphe nuclei of the midbrain?
Substantia nigra- [pars compacta] is a source of dopamine
Raphe nuclei- source of serotonin
What is the job of the following structures of the midbrain:
- red nucleus
- superior colliculus
- inferior colliculus
- posterior commissure
- relays signals btw cerebellum and thalamus; cerebellum and inferior olive
- rapid reflexive movement of the head and eyes to sensory stimuli
- auditory relay nucleus
- carries axons involved in consensual light reflex
What 3 cranial nerve nuclei are located in the midbrain?
- oculomotor complex [3]
- Edinger-Westphal nucleus
- trochlear nucleus [4]
What are the 3 major structures of the pons?
What is the role of each?
- Basal pons :
- basal pontine nuclei cross the midline and travel to the contralateral cerebellar hemisphere
- axons descend to the medulla and spinal cord - ascending sensory axons
- medial leminiscus
-anterolateral pathway
[located in pontine tegmentum] - locus ceruleus
- noradrenergic projections
- raphe nuclei
What are the cranial nerve nuclei of the pons?
- trigeminal nuclei [5]
- abducens [6]
- facial [7]
- vestibulocochlear [8]
What are the 3 major structures of the medulla oblongata?
What is the function of each?
- Pyramids
- descending motor axons [85% cross, 15% ipsi] - Olives
- climbing fibers cross and ascend to contralateral cerebellum - Medial leminiscus
- decussating fine touch, proprioception fibers that originated in the gracile and cuneate nuclei
- ascending anterolateral pain/temp fibers
What CN originate in the medulla?
- spinal trigeminal [5]
- hypoglossal [12]
- dorsal motor nucleus of the vagus [X]
- nucleus ambiguus
- solitary nucleus
- vestibular [8]
- cochlear
What 4 vessels supply the rostral brainstem?
- posterior cerebral artery [PCA]
- superior cerebellar artery
- anterior inferior cerebellar artery
- basilar artery
What 4 vessels supply the caudal brainstem?
- vertebral arteries
- anterior spinal
- posterior spinal
- posterior inferior cerebellar artery
What is the function of the following nerves:
- oculomotor
- trochlear
- trigeminal
- abducens
- facial
- MR, SR, IR, IO, levator palpebrae superioris, parasympathetic motor axons from EW to ciliary ganglion of the eye
- SO
- muscles of mastication, tensor tympani ; sensory from face; mechanoreceptor from oral cavity
- LR
- facial expression, stapedius, parasympathetic to lacrimal, submandibular, sublingual; taste from ant 2/3; pain from ear
What is the function of the following nerves:
- vestibulocochlear
- glossopharyngeal
- vagus
- spinal accessory
- hypoglossal
- inner ear sensory
- stylopharyngeus [swallowing], parasym to parotid; taste from post 1/3; baro/chemoreceptors; pain from ear
- larynx, pharynx; parasymp to thoracic/abdominal viscera; epiglottis; pain from ear
- pharyngeal, laryngeal, SCM, trapezius muscles
- muscles of tongue
What are the 3 functional divisions of the cerebellum and what is the role of each?
- vestibulocerebellum - flocculi and nodulus control balance and eye movements
- spinocerebellum - vermis [except nodulus and paravermal cortex] controls axial and distal muscles
- neocerebellum - motor memory and execution of complex motions
If there is damage to the hemisphere of the cerebellum, where would you notice the damage?
What would the problem be?
Hemispheric damage to the cerebellum results in IPSILATERAL abnormalities in fine motor control.
Describe the presentation of a midline/vermal lesion of the cerebellum. What side of the body is affected? What is the problem?
Vermal lesions result in :
- abnormal balance
- abnormal gait [ataxia]
- abnormal eye movements
on BOTH sides of the body
What is blood supply to the cerebellum?
- paired PICAs [post, inf. cerebellar arteries]
- AICAs [ant. inf, cerebellar arteries
- superior cerebellar arteries
In the spinal cord, where do motor neurons lie?
What 2 diseases affect these neurons specifically?
Motor neurons lie in the ventral grey matter and are the target of:
- ALS
- spinal muscular atrophy
What are the descending motor tracts of the spinal cord and where are they located?
85% of the descending motor neurons cross in the pyramids of the medulla and run in the contralateral lateral corticospinal tracts.
[lateral white matter]
What nuclei are in the dorsal columns of the spinal cord?
What do the axons convey information about? From what part of the body?
The dorsal columns contain the gracile and cuneate fasiculi.
Cuneate - C1 to T6 so fine touch, proprioception, vibration from the arms/upper body
Gracile - fine touch, proprioception, and vibration from the lower extremities
What is blood supply to the spinal cord?
- anterior spinal artery [front 2/3]
- posterior spinal arteries [posterior 1/3]
- radicular arteries
Describe the pathway of the descending corticospinal tracts.
- Primary motor cortex [just in front of central sulcus]
- posterior limb of internal capsule to ipsilateral cerebral peduncles of midbrain
- In the pyramids of the medulla 85% of fibers cross and continue in the contralateral corticospinal tract, while 15% remain ipsilateral
- synapse on neurons of the anterior horn
Injury to motor neurons or their descending axons cause what type of symptoms?
UMN signs and symptoms like:
- weakness
- spasticity
- hyper-reflexia