13 Brain and Cranial Nerves Flashcards
Where are the brain ventricles located and what are they continuous with?
The 2 lateral ventricles are in the cerebrum, separated by the septum pellucidum. The third ventricle is within the diencephalon (superior to and overlapping thalmus on midsagittal sheep brain.) The cerebral aqueduct connnects it to the fourth ventricle, between pons and cerebellum. It then opens to the subarachnoid space and central canal of the spinal cord.
What are the functions of CSF?
(1) provide buoyancy (decrease brain weight by 95%)
(2) provide protection (liquid cushion)
(3) provide environmental stability (transport nutrients/chemical messengers to brain, remove waste products, protect from chemical fluctuations.)
Where is the BBB absent?
choroid plexus
hypothalamus
pineal gland
Primary motor cortex
located on the precentral gyrus
controls voluntary motor functions
Premotor cortex
located to anterior to the precentral gyrus/primary motor cortex
coordinates skilled motor activities
motor speech area
Broca area
controls movement for vocalizaion
inferiolateral portion of frontal lobe along lateral sulcus
frontal eye field
regulates eye movements needed for reading and binocular vision
located between Broca area (motor speech) and the premotor cortex
primary somatosensory area
receives/processes/stores somatic sensory information from proprioceptors, touch pressure, pain and temp receptors
parietal lobe: located in the postcentral gyrus
somatosensory association area
integrates and interprets sensory information, determines texture, temperature, pressure and shape of objects (ID objects without seeing them)
parietal lobe: located posterior to the primary somatosensory area
primary visual cotex
receives and processes incoming visual information
occipital lobe: posterior most point
visual association cortex
integrates and interprets visual information (id things we see)
occipital lobe: anterior to primary visual cortex
primary auditory cortex
receives and processes auditory information
temporal lobe: near juncture of central sulcus and lateral sulcus
auditory association area
interprets characteristics of sound, stores memories of sound heard in the past
temporal lobe: posteroinferior to auditory cortex
primary olfactory cortex
provides conscious awareness of smell
temporal lobe
primary olfactory cortex
provides conscious awareness of smell
temporal lobe: anterior to auditory areas
primary gustatory cortex
involved in processing taste information
located in insula
prefrontal cortex
functional brain region
complex thought, judgement, personality, planning, decision making, located rostral to premotor cortex
Wernicke area
involved in recognizing, understanding and comprehending spoken and written language, works with motor speech area, typically located only in the left hemisphere
includes an area of temporal and parietal lobes
Gnostic area
integrates somatosensory, visual, and auditory information of association areas, provides comprehensive understanding of current activity, composed of regions of parietal, occipital and temporal lobes
What are the three tracts in the cerebrum?
-Association tracts - connect different regions of cerebral cortex within the same hemisphere
-Commissural tracts - extend between hemispheres (corpus callosum)
-Projection tracts - links the cerebral cortex to inferior brain regions and the spinal cord (corticospinal tract)
CN I
Olfactory nerve
sensory
olfaction
CN II
Optic nerve
sensory
vision
CN III
Oculomotor
motor (includ
four extrinsic eye muscles, elevates eyelid (somatic)
constricts pupils, rounds lens of eye (parasympathetic)
CN IV
Trochlear nerve
motor
superior oblique eye muscle
CN V
Trigeminal nerve
both
sensory from anterior scalp, face, oral cavity, teeth and others
muscles of mastication and others
CN VI
Abducens
motor
lateral rectus eye muscle (abducts the eye)
CN VII
Facial nerve
both
-taste anterior tongue
-muscles of facial expression, others (somatic)
-gland secretions from lacrimal, submandibular, and salivary glands (except parotid/glossopharyngeal) (parasympathetic)
CN VIII
Vestibulocochlear nerve
both (mostly sensory)
hearing, equilibrium
CN IX
Glossopharyngeal
both
special sensory - taste to posterior tongue
somatic sensory - part of pharynx and posterior tongue
visceral sensory - from carotid chemoreceptors/baroreceptors
stylopharyngeus muscle (motor)
secretions from the parotid gland (parasympathetic)
CN X
Vagus nerve
both
Motor for parasymphathetic nerves to the heart, lungs, and visceral organs
Sensory for same organs
Required for speech, pharyngeal muscles (motor)
Only cranial nerve to extend beyond head and neck
CN XI
Accessory nerve
motor
trapezius and sternocleidomastoid muscle
CN XII
Hypoglossal
motor
intrinsic and extrinsic tongue muscles
Which CNs have parasympathetic motor function?
CN III Oculomotor - sphincter pupillae and ciliary
CN VII Facial - lacrimal gland, submandibular and sublingual salivary glands
CN IX Glossopharyngeal - parotid salivary gland
CN X - Vagus - smooth muscle and glands of most thoracic and abdominal organs
What is the function of the thalamus?
Functions to
(1) receive impulses from all conscious senses except olfaction
(2) groups axons projecting to particular regions of the cortex
(3) sensory information is projected to the primary somatosensory cortex
(4) information filter (filters out sounds in a busy cafeteria)
(In the lateral walls of third ventricle. Composed of a gray matter mass, the thalmic nuclei)
What is the function of the epithalmus?
The epithalmus contains the pineal gland which secreted melatonin.
The epithalmus partially forms the roof of the diencephalon and covers the third ventricle.
What is the function of the hypothalmus?
Functions
(1) master control of the autonomic nervous system (influences HR, BP, digestion, resp)
(2) master control of the endocrine system (hormones that activate pituitary gland, also ADH and oxytocin)
(3) regulation of body temperature
(4) control of emotional behavior (center of limbic system)
(5) control of food intake
(6) control of water intake
(7) regulation of sleep-wake rhythms
anteroinferior regioins of the diencephalon. the infundibulum connects the hypothalamus to the pituitary gland.
What are the parts and functions of the midbrain?
Cerebral peduncles - connect the brain-stem to the cerebrum and carry voluntary motor commands from the primary motor cortex
Superior cerebellar peduncle - connects the midbrain to the cerebellum
Substantia nigra - bilaterally symmetric nuclei, houses clusters of neurons that produce dopamine
Tectum - posterior regions of the midbrain, contains tectal plate composed of two pairs of sensory nuclei: the superior colliculi (visual reflex centers, help visually track moving objects) and inferior colliculi (auditory reflex centers, control reflexive turning of head in direction of sound)
Cerebral aqueduct-extends through the midbrain
What is the function of the pons?
The pons is the buldging region on the anterior brainstem.
It contains sensory and motor tracts connecting the brain and spinal cord.
It also contains the pontine respiratory center which regulates the skeletal muscles of breathing.
What is the function of the medulla oblongota?
The medulla oblongata is continuous with the spinal cord inferiorly.
All tracts between the brain and spinal cord pass through the medulla.
It contains several autonomic nuclei that group together to form autonomic centers: the cardiac center (regulates heart rate and strength of contraction), the vasomotor center (controls blood pressure) and the medullary respiratory center (regulates respiratory rate.)
What are the functions of the cerebellum?
(1) The cerebellum coordinates and “fine-tunes” skeletal muscle movements, initiated by the cerebrum, to ensure it follows the correct pattern leading to smooth, coordinated movements. (2) It helps maintain equilibrium and posture. (3) Receives proprioceptive information from muscles and joints to regulate the body’s position (4) Continuously receives input from sensory and motor pathways (5) Monitors muscular activity
What is the function of the limbic system?
The limbic system is considered the emotional brain. It functions to collectively process and experience emotions.
What is the function of the RAS?
The reticular activating system is the sensory component of the reticular formation, responsible for alerting the cerebrum to incoming sensory information.
The reticular formation is a loosely organized core of gray matter that projects vertically through the core of the brainstem. The motor component communicates with the spinal cord and is responsible for regulating muscle tone and assists in autonomic functions (heart rate, BP, resp with the medulla and pons.) The sensory component is termed the RAS. It contains sensory axons projecting to the cerebral cortex and it processes visual, auditory, and touch stimuli and uses this information to keep us in a state of alertness. Not active or l`ess active during sleep.
What are higher order mental functions and where do they occur in the brain?
Includes: learning, memory and reasoning
;Occur within the cerebral cortex and involve multiple brain regions connected by complicated networks and arrays of axon.
Sensory memory
forms from important associations based on sensory input from the environment
lasts seconds
Short term memory
limited capacity (~7 small pieces of information) and lasts briefly
(seconds to hours)
Long term memory
Can be converted from STM if repeated (encoding) and may exist for limitless periods of time
Stored mainly in association areas and needs to be retrieved occasionally or may be lost.
What are the brain regions involved with language?
-Wernicke area - involved in interpreting written and oral language and produce understandable speech
-Broca area/ motor speech area- receive axons from Wernecke area, regulates motor activities needed for speech, sends signals to primary motor cortex
-Primary motor cortex - signals motor neurons to produce speech
