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 betwene 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
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 tissues
-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
-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
Circulation of CSF step 2
-choroid plexus of the third ventricle adds more CSF and then flows into the 4th ventricle via the aqueduct of the midbrain
Circulation of CSF step 3
-choroid plexus of the fourth ventricle adds more CSF and then flows into the subarachnoid space via the one median aperture and the two lateral apertures
Circulation of CSF step 4
-after flowing through subarachnoid space
-CSF is gradually reabsorbed into the blood through the arachnoid granulations
Arterial supply of the brain sources
-internal carotid and vertebral arteries
How does blood return to systemic circulation
-from dural venous sinuses drain into internal jugular veins
The cerebral arterial circle (of willis)
-anatomical structure that provides an anastomotic connection between the anterior and posterior circulations
Main arteries of the anterior circulation
-internal carotid artery
-anterior cerebral artery
-anterior communicating artery
-middle cerebral artery
Supply of the anterior circulation
-forebrain
Main arteries of the posterior circulation
-vertebral artery
-basilar artery
-posterior cerebral artery
-posterior communicating artery
Supply of the posterior circulation
-posterior cortex
-midbrain
-brainstem
-cerebellum
Main arteries of the circle of willis
-anterior communicating artery
-anterior cerebal arteries
-internal carotid arteries
-posterior communicating arteries
-posterior cerebral arteries
Supply of the anterior cerebral artery
-frontal, parietal, and cingulate cortex
-corpus callosum
Supply of the middle cerebral artery
-lateral surface of the frontal, parietal and temporal lobes
-basal ganglia and internal capsule
Supply of the posterior cerebral artery
-occipital lobe
-inferolateral surface of the temporal lobe
-midbrain
-thalamus
-choroid plexus
-cerebral peduncles
3 parts of the autonomic nervous system
-sympathetic
-parasympathetic
-visceral
What regulates the autonomic nervous system
-hypothalamus and brain stem
2 motor neurons in the autonomic nervous system
-preganglionic
-postganglionic
Preganglionic neuron
-cell body in CNS and axon extends to autonomic ganglion
Postganglionic neuron
-cell body in autonomic ganglion and axon extends to autonomic effector
Autonomic plexus
-tangled network of axons of preganglionic neurons located in thorax, abdomen and pelvis
Sympathetic trunk ganglia
-sites of synapse between sympathetic preganglionic and postganglionic neuron cell bodies
What are the 3 pairs of cervical sympathetic trunk ganglia located in the neck
-superior
-middle
-inferior
How many thoracic pairs are in the sympathetic trunk ganglia
-12
Grey communicating rami
-structures containing the postganglionic unmyelinated axons
Prevertebral ganglia
-anterior to vertebral column and close to large abdominal arteries
5 major prevertebral ganglia
-celiac ganglion
-superior and inferior mesenteric ganglia
-aorticorenal ganglion
-renal ganglion
4 parasympathetic ganglia
-ciliary ganglia
-pterygopalatine ganglia
-submandibular ganglia
-otic ganglia
Protective structures of the spinal cord
-the vertebral column
-3 spinal meninges
-a cushion of cerebrospinal fluid
What is included in the vertebral column
-vertebrae
-vertebral ligaments
3 spinal meninges
-dura mater
-arachnoid mater
-pia mater
Spinal cord shape
-oval
-extends from medulla oblongata to the second lumbar vertebrae
2 enlargements of the spinal cord
-cervical enlargement
-lumbar enlargement
Conus medullaris
-where the spinal cord terminates
Filum terminale
-extension of the pia mater that extends from the conus medullaris and fuses with the arachnoid and dura mater to attach spinal cord to coccyx
Cauda equina
-“horses tail”
-lumbar, sacral and coccygeal spinal nerves emerging from the lower part of the spinal cord
Internal matter of spinal cord
-core of grey matter
-surrounded by white matter
2 grooves of the spinal cord
-anterior median fissure
-posterior median sulcus
Horns of the spinal cord
-anterior grey horns
-posterior grey horns
-lateral grey horns
Funiculi of the spinal cord
-anterior funiculi
-posterior funiculi
-lateral white funiculi
Tracts of the spinal cord
-sensory (ascending) tracts
-motor (descending) tracts
What to white matter tracts of the spinal cord do
-transmit nerve impulses between brain and periphery
What do grey matter tracts of the spinal cord do
-receives and integrates incoming and outgoing information
Lateral spinothalamic tract functions
-pain
-temperature
Anterior spinothalamic tract functions
-deep pressure
-fine touch, itching, tickling
-crude, poorly localized touch
Direct descending pathways of the spinal cord functions
-cause precise, voluntary movements of the trunk and limbs
-voluntary actions of the face, head, and neck
How many pairs of spinal nerves are there
-31
How are spinal nerves named
-according to region and level of spinal cord from which they emerge
How many pairs of cervical nerves are there
-8
How many pairs of thoracic nerves are there
-12
How many pairs of lumbar nerves are there
-5
How many pairs of sacral nerves are there
-5
How many pairs of coccygeal nerves are tehre
-1
Anterior spinal root
-motor neuron axons
Posterior spinal root
-sensory nerve fibres
-contains posterior root ganglion
Posterior root ganglion
-enlargement of the posterior spinal root that contains sensory neuron cell bodies
Spinal nerve trunk
-anterior and posterior root merge to form this
-results in every nerve being a mixed nerve
Posterior ramus of spinal nerve trunk
-serves the deep muscles and skin of the posterior surface of the trunk
Anterior ramus of spinal nerve trunk
-serves the muscles and structures of the upper and lower limbs
-has 2 small visceral branches
Meningeal branch of anterior ramus
-reenters vertebral canal
-supplies vertebrae, vertebral ligaments, blood vessels of the spinal cord and meninges
Communicating rami of anterior ramus
-components of the autonomic division of the PNS
How many cranial sensory nerves are there?
-3
How many cranial motor nerves are there?
-4
How many cranial mixed nerves are there?
-5
Olfactory nerve (I) classification
-sensory
Olfactory nerve (I) function
-olfaction (sense of smell)
Olfactory nerve (I) passage
-pass through cribriform plate and synapse with other neurons in the olfactor bulbs
-or form the olfactory tracts and travel to olfactory area
Optic nerve (II) classification
-sensory
Optic nerve (II) function
-vision
-signals from rods and cones are relayed to ganglion cells
Optic chiasm
-2 optic nerves unite and cross over to form this area
-medial side fibres cross over
-lateral side fibres remain on the same side
Optic tract
-posterior to optic chiasm, regrouped fibres form the optic tracts
Optic nerve (II) passage
-most fibres travel to the lateral geniculate nuclei in the thalamus
-some travel to the superior colliculli of the midbrain
Oculomotor (III) nerve classification
-motor
Oculomotor nerve (III) function
-innervated both extraocular and intrinsic smooth eyeball muscles
Oculomotor nerve (III) divisions
-superior and inferior branches
-both enter eye orbit via superior orbital fissure
Oculomotor nerve (III) superior branch innervates what
-superior rectus and levator palpebrae superioris muscles (upper eyelid)
Oculomotor nerve (III) inferior branch innervates what
-medial rectus
-inferior rectus
-inferior oblique
-also provides parasympathetic innervation to ciliary ganglion
Oculomotor nerve (III) specific functions
-regulating movements of upper eyelid and eyeball
-adjustment of lens for near vision
-contstriction of pupil
Trochlear nerve (IV) classification
-motor
Trochlear nerve (IV) function
-movement of eyeball
Trochlear nerve (IV) passage
-originates in midbrain and enters orbit via superior orbital fissure
Trigeminal nerve (V) classification
-mixed
Trigeminal nerve (V) nerve branches
-opthalamic nerve
-maxillary nerve
-mandibular nerve
Sensory portion of trigeminal nerve function
-touch
-pain
-thermal sensations
Motor portion of the trigeminal nerve function
-supply the muscles of mastication
Ophthalmic nerve (branch of trigeminal) passage
-enters the orbit via superior orbital fissure
Maxillary nerve (branch of trigeminal) passage
-passes through the foramen rotundum
Mandibular nerve (branch of trigeminal) passage
-exits through the foramen ovale
Ophthalmic nerve (branch of trigeminal) function
-carries signals from upper eyelid, lacrimal glands, cornea, upper part of nasal cavity, side of the nose, forehead and anterior half of scalp
Maxillary nerve (branch of trigeminal) function
-carries signals from the nasal mucosa, palate, part of pharynx, upper teeth, upper lip, lower eyelid
Mandibular nerve (branch of trigeminal) function
-carries signals from anterior 2/3 of the tongue, lower teeth, cheek, skin over mandible, floor of mouth
Abducens nerve (VI) classification
-motor
Abducens nerve (VI) passage
-travel from the nucleus to the lateral rectus muscle via the superior orbital fissure of the orbit
Abducens nerve (VI) function
-abduction of the eyeball
Facial nerve (VII) classification
-mixed
Facial nerve (VII) passage
-sensory portion: from tastebuds of tongue to special sensory ganglion to a nucleus in the pons
-motor portion: from nucleus in the pons to innervate middle ear, facial, scalp and neck muscles
Facial nerve (VII) function
-skin sensations
-innervation of skeletal muscles involved in facial expression
-parasympathetic innervation to various glands in the head
Vestibulocohlear nerve (VIII) classification
-sensory
Vestibulocochlear nerve (VIII) branches
-vestibular branch
-cochlear branch
What is the vestibular branch of the vestibulocochlear nerve associated with
-pons
What is the cochlear branch of the vestibulocochlear nerve associated with
-medulla
Vestibular branch (vestibulocochlear nerve) function
-sends nerve impulses to inner ear structures
Cochlear branch (vestibulocochlear nerve) function
-transmits nerve impulses associated with hearing
Glossopharangeal nerve (IX) classification
-mixed
Glossopharangeal nerve (IX) passage
-sensory: originate from taste buds to the medulla
-motor: originate from nuclei and exit from the jugular foramen
Glossopharangeal nerve (IX) sensory functions
-taste, proprioceptors, monitoring blood pressure, monitoring blood gas levels
Glossopharangeal nerve (IX) motor functions
-innervate the stylopharngeus muscle which aids in swallowing
Vagus nerve (X) classification
-mixed
Vagus nerve (X) passage
-travel from visceral sensory receptors of thoracic and abdominal organs etc
Vagus nerve (X) sensory function
-taste, blood pressure monitoring and blood gas monitoring
Vagus nerve (X) motor function
-supply smooth muscles in the respiratory passageways, lungs, esophagus, stomach, small intestine
Accessory (XI) nerve classification
-mixed
Accessory nerve (XI) passage
-gray horn of cervical spinal cord, enter the foramen magnum and exit via the jugular foramen
Accessory nerve (XI) sensory function
-proprioception, pain
Accessory nerve (XI) motor function
-transmit impulses to the sternocleidomastoid and trapezius muscles
-coordinate head and pectoral girdle movements
Hypoglossal nerve (XII) classification
-motor
Hypoglossal nerve (XII) passage
-originate in a nucleus in the medulla, travel through hypoglossal canal and innervate muscles of the tongue
Hypoglossal nerve (XII) function
-transmit nerve impulses related to speech and swallowing
Somatic motor pathways
-begin in neural circuits in the brain and spinal cord which create the motor signals that result in the production of all voluntary and involuntary movements
Where are lower motor neurons
-cell bodies are in the brain stem and spinal cord
3 groups of neurons that participate in control of movement by providing input to lower motor neurons
-upper motor neurons
-corpus striatum neurons
-cerebellar neurons
Upper motor neurons types
-primary motor cortex UMNs
-brainstem UMNs
Primary motor cortex UMNs function
-carry signals involved in motor planning and execution of voluntary movements
Brainstem UMNs function
-carry motor output to help regulate posture, balance, muscle tone and reflexive head and trunk movements
Corpus striatum neurons
-assist movement
Cerebellar neurons
-assist movement
Direct motor pathways
-provide input to lower motor neurons via axons that extend directly from cerebral cortex
Indirect motor pathways
-provide input to lower motor neurons from motor centers in the brain stem
Premotor area (in cerebral cortex) function
-receives signal regarding the desire to move a body part and then creates the motor plan
Primary motor area (in cerebral cortex) function
-major control center for initiation and execution of voluntary movements
Corpus striatum functions
-initiating and terminating movements
-suppressing unwanted movements
-controlling the level of muscle tone
-influencing cortical function
Cerebellar movement functions
-monitoring intentions for movements
-monitoring actual
-comparing command signals with sensory information
-sending out corrective feedback signals
Vestibular nuclei in medulla and pons function
-control postural reflexes
-nuclei receives sensory input from the eyes
-the vestibular apparatus of the inner ear
-proprioceptors in muscles and joints
Reticular formation in the medulla, pons, and midbrain function
-helps control posture
-receives input eyes, ears, cerebellum, and corpus striatum
Superior colliculus of the midbrain function
-receives visual and auditory input that stimulates the body to turn in the direction of a sudden visual or auditory cue
Meningeal sinuses
-superior sagittal sinus
-inferior sagittal sinus
-transverse sinus
-straight sinus
-sigmoid sinus
-cavernous sinus
