Chapter Two: The Brain/Nervous System Flashcards
Parts of the brain
-cerebrum
-cerebellum
-brain stem
Parts of the cerebrum
-telencephalon
-diencephalon
Brain stem components
-mid brain
-pons
-medulla oblongata
The diencephalon location
-forms central core of brain tissue
-superior to midbrain
-extends from brainstem to cerebrum and surrounds the third ventricle
Main structures of the diencephalon
-thalamus
-hypothalamus
-epithalamus
-subthalamus
Thalamus location
-superior to midbrain
-80% of diencephalon
-beside 3rd ventricle
Functions of the thalamus
-major relay station for sensory impulses (except smell), transmitted from spinal cord, brainstem and midbrain
-perception of pain, temp, proprioception and pressure
Interthalamic adhesion
-bridge of gray matter that connects the right and left portions of the thalamus
Internal capsule
-connects the thalamus to the cerebral cortex
-thick band of white matter
Hypothalamus location
-small region of diencephalon located inferior to the thalamus
-beside 4th ventricle
Divisions of the hypothalamus
-posterior hypothalamic (mammillary area)
-infundibulum (connects to pituitary gland)
Hypothalamus functions
-major regulator of homeostasis
-control of the autonomic nervous system
-production of hormones
-regulation of emotional and behavioural patterns
-regulation of eating and drinking
-regulation of body temperature
-regulation of circadian rhythms and states of consciousness
Epithalamus location
-small region superior and posterior to the thalamus
Epithalamus function
-contains pineal gland which secretes melatonin
-helps regulate circadian rhythms, wakefulness, hormone secretion and body temp
Basal ganglia location
-3 masses of gray matter nuclei located deep within the cerebral hemispheres
The corpus striatum (basal ganglia) consists of
-caudate nucleus
-lentiform nucleus (globus pallidus)
Claustrum
-thin sheet of grey matter that is sometimes included as part of the corpus striatum; believed to be involved in visual attention
Functions of the corpus striatum (basal ganglia)
-help regulate the initiation and termination of movements
-control subconscious movements of skeletal muscles
-help initiate and terminate some cognitive processes and may help regulate emotional behaviours
Midbrain location
-extends upwards from pons to diencephalon
-aqueduct of midbrain passes through
Cerebral peduncles
-on the anterior portion of the midbrain
-contain axons of pyramidal tracts
Colliculi
-on the midbrain
-superior colliculi: serve as reflex centers for visual activities
-inferior colliculi: help relay auditory information from the ears to the thalamus
Nerves coming off the midbrain
-oculomotor (III) nerve
-trochlear (IV) nerve
Pons location
-superior to medulla and anterior to cerebellum
Pons 2 regions
-ventral region: grey matter called pontine nuclei
-dorsal region: various ascending and descending tracts (white matter)
Pontine respiratory group
-works with medullary respiratory center to help control breathing
Cranial nerves coming off the pons
-trigeminal (V) nerve
-abducens (VI) nerve
-facial (VII) nerve
-vestibulocochlear (VIII) nerve
Medulla oblongata location
-continuation of superior part of spinal cord and forms the inferior part of the brain stem
Medulla oblongata function
-contains all sensory and motor tracts that connect the spinal cord to the brain
-also contains many nuclei that regulate various vital body functions
Pyramids
-anterior bulges on the medulla
-contain the largest motor tracts that pass from cerebrum to spinal cord
Decussation of pyramids
-feature that results in motor fibres originating in the left cerebral cortex activating muscles on the right side of the body and vice versa
Medulla nuclei controls
-cardiovascular center: rate and force of heartbeat and blood vessel diameter
-medullary repiratory center: basic breathing rhythm
-other centers: control reflexes for vomiting, swallowing, coughing, sneezing, and hiccuping
Olive
-lateral to the pyramids
-contains the inferior olivary nucleus
-relays impulses from proprioceptors to the cerebellum
Cranial nerves coming from the medulla
-vestibulocochlear (VIII) nerve (cochlear branch)
-glossopharangeal (IX) nerve
-vagus (X) nerve
-accessory (XI) nerve
-hypoglossal (XII) nerve
The cerebellum location
-located in the inferior and posterior aspects of the cranial cavity
Transverse cerebral fissure
-seperates the cerebrum and the cerebellum
Tentorium cerebelli
-extension of dura mater that helps seperate the cerebrum and cerebellum
Vermis
-connects the 2 halves of the cerebellum
-central area of the cerebellum that makes it look like a butterfly
Lobes of the cerebellum
-anterior
-posterior
Falx cerebelli
-extension of dural mater between the hemispheres of the cerebellum
Cerebellar cortex
-superficial layer of the cerebellum
-contains ridges called folia
Arbor vitae
-branches of white matter in the cerebellum
How is the cerebellum connected to the brain stem
-inferior cerebellar peduncles
-middle cerebellar peduncles
-superior cerebellar peduncles
Inferior cerebellar peduncles
-carry sensory information
-connect to medulla
Middle cerebellar peduncles
-contain axons that extend from cerebrum and pons to the cerebellum
Superior cerebellar peduncles
-contains axons that extend from the cerebellum to the midbrain
Functions of the cerebellum
-to evaluate how well the movements initiated by the motor areas of the cerebrum are actually being carried out
-to regulate posture and balance
4 main regions of the brain
-cerebrum
-diencephalon
-brain stem
-cerebellum
The cerebrum function
-performs many mental tasks such as reading, writing, speaking, calculating, composing, imagining, memory, planning etc
Cerebrum structure
-largest part of the brain
-consists of right and left cerebral hemispheres and the corpus striatum
Cerebral cortex
-surface layer of grey matter that covers each cerebral hemisphere
Cerebral gyri
-ridges in the cortex
Cerebral fissures
-deep grooves between folds
Cerebral sulci
-shallow grooves between folds
Cerebral fissures
-grooves that seperate parts of the brain
Longitudinal cerebral fissure
-separates the cerebrum into right and left cerebral hemispheres and connected by the corpus callosum
Falx cerebri
-extension of the dura mater that seperates the 2 cerebral hemispheres
Lobes of the cerebrum
-frontal lobe
-parietal lobe
-temporal lobe
-occipital lobe
Central cerebral sulcus
-seperates the frontal lobe from the parietal lobe
Precentral gyrus
-anterior to the central sulcus
-contains the primary motor area
Postcentral gyrus
-posterior to the central sulcus
-primary somatosensory area
Lateral cerebral sulcus
-separates the frontal lobe from the temporal lobe
Parieto-occipital sulcus
-separates the parietal lobe from the occipital lobe
Insula location
-part of the cerebrum
-located within the lateral cerebral sulcus, deep to the parietal, frontal and temporal lobes
-need to pull back these lobes in order to see it
Tracts of the cerebrum
-association tracts
-commissural tracts
-projection tracts
Association tracts function
-conduct nerve impulses between cerebral gyri within the same cerebral hemisphere
Types of commisural tracts
-corpus callosum
-anterior commissure
-posterior commissure
Commissural tracts function
-conduct nerve impulses from cerebral gyri in one cerebral hemishpere to a cooresponding gyrus in the other cerebral hemisphere
Projections tracts function
-conduct nerve impulses from the cerebrum to lower parts of the CNS or from lower CNS parts to the cerebrum
Frontal lobe function
-control of voluntary movement
-involved in attention
-short term memory tasks
-motivation
-planning
-speech
Parietal lobe function
-integrates proprioceptive and mechanoceptive stimuli
-involved in language processing
Temporal lobe function
-decoding sensory input into derived meanings for retention of visual memory and language comprehension
Occipital lobe function
-center for visual processing
Insular lobe function
-processing and integration of taste sensation
-visceral and pain sensation
-vestibular functions
Limbic lobe function
-modulation of emotions
-modulation of visceral and autonomic functions
-learning and memory
Sensory areas of the cerebral cortex
-primary somatosensory area
-primary visual area
-primary auditory area
-gustatory area
-olfactory area
Primary somatosensory area
-located in the postcentral gyrus
-receives information for touch, proprioception, pain, tickle, itch and thermal sensations
Primary visual area
-located in the posterior occipital lobe
-receives impulses from visual receptors and is involved in visual perception
Primary auditory area
-located in the temporal lobe
-receives impulses from auditory receptors and is involved in auditory perception
Gustatory area
-located in insula
-receives impulses for taste and is involved in gustatory perception
Olfactory area
-located in superior temporal gyrus
-receives impulses from olfactory receptors and is involved in smell perception
Motor areas of the cerebral cortex
-primary motor area
-premotor cortex
-brocas area
Primary motor area
-located in the precentral gyrus of frontal lobe
-controls voluntary skeletal muscle contraction
Premotor cortex
-located anterior to primary motor cortex
-involved in motor planning to cause specific muscle groups to contract simultaneously and serves as a muscle memory bank for coordinated movements
Brocas area
-located in the left frontal lobe
-involved in the planning and production of speech
Association areas
-somatosensory association area
-motor association area
-visual association area
-auditory association area
-wernicke’s area
Somatosensory association area
-located posterior to primary somatosensory cortex (post central gyrus)
Motor association area
-located anterior to the precentral gyrus of the frontal lobe
Visual association area
-located in the occipital lobe outside the cuneus
Auditory association area
-located in temporal lobe
Wernickes area
-located in the left temporal and parietal lobes
Protection of the brain
-cranial bones
-cranial meninges
3 meninges layers
-dura mater
-arachnoid mater
-pia mater
Dura mater layers
-periosteal layer (external)
-meningeal layer (internal)
Epidural space
-exists between the periosteal layer of dura mater and the cranial bones
Extensions of the dura mater
-falx cerebri
-falx cerebelli
-tentorium cerebelli
Arachnoid mater
-middle layer
Arachnoid granulations
-look like balloons
-regulate the release of CSF into the dural venous sinuses
Arachnoid trabeculae
-thin projections of connective tissue
-extend from arachnoid to pia mater
Subarachnoid space
-between arachnoid and pia mater
-fluid filled space occupied by CSF
Pia mater
-inner layer
-thin membrane composed of a single cells layer
-follows the contours of the gyri and sulci of the brain
Subpial space
-seperates pia mater from cerebral cortex
What is CSF
-clear liquid that protects the brain and spinal cord
-carries oxygen etc
Which ventricles do CSF travel through
-right and left lateral ventricles
-third ventricle
-fourth ventricle
Lateral ventricles location
-located in the 2 central hemishperes
Third ventricle location
-between right and left halves of the thalamus
Fourth ventricle location
-located between brain stem and cerebellum
How is CSF formed
-as blood flows through choroid plexuses located in the walls of the ventricles
CSF functions
-mechanical protection
-chemical protection
-circulation
Circulation of CSF step 1
-CSF produced in choroid plexuses of lateral ventricles flows into the third ventricle via interventricular foramen