Test 2 Flashcards
Learning objectives
- Identify the major structures of the brainstem and describe their general functions
- Name the 12 cranial nerves and their sensory/motor properties
- Describe the origin, course & major function of cranial nerves I and II
- Understand how visual field deficits arise
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Brainstem
Consist of the?
Positioned b/w?
Connected dorsally to the?
Provides a pathway for …. running b/w the forebrain, cerebellum & spinal cord
Associated w/ 10 of the 12 pairs of?
Brainstem
Consist of the?
- Midbrain
- Pons
- Medulla
Positioned b/w?
- The forebrain & spinal cord
Connected dorsally to the?
- Cerebellum
Provides a pathway for AXONAL TRACTS running b/w the forebrain, cerebellum & spinal cord
Associated w/ 10 of the 12 pairs of?
- Cranial nerves
Midbrain
Name the structures:
Midbrain
Name the structures:
- Cerebral peduncles
- Corpora quadrigemia (quadruplets)
- Superior colliculi
- Inferior colliculi
- Substantia nigra
- Red nucleus
- Cranial nerves
- oculomotor (III)
- trochlear (IV)
- Cerebral aqueduct
- Superior cerebellar peduncles
Midbrain - Cerebral Peduncles
Includes axons that descend from the cerebral cortex to the?
Passes longitudinally on the …. surface of the ….
Help to … the cerebrum to the …
…… nerves emerges anterior
….. nerves emerges posterior
Midbrain - Cerebral Peduncles
Includes axons that descend from the cerebral cortex to the?
- Brainstem and spinal cord
Passes longitudinally on the VENTRAL surface of the MIDBRAIN
Help to ANCHOR the cerebrum to the BRAINSTEM
III CRANIAL nerves emerges anterior
IV CRANIAL nerves emerges posterior
Midbrain - Cerebral Peduncles
Locate the Aqueduct of syivius & Peduncle
- L6, page 6
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Midbrain - Corpora quadrigemia: Superior & Inferior Colliculus
Locate the Superior & Inferior Colliculus
- L6, page 7
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Superior colliculi (visual reflex centres)
Receives inputs from the ….. & projects to ….
Concerned with the detection of …. in the visual field
Relay vision information to neurons innervating the …..
Superior colliculi (visual reflex centres)
Receives inputs from the RETINA/VISUAL CORTEX & projects to VISION-RELATED AREAS IN CORTEX
Concerned with the detection of MOVEMENT OF OBJECTS in the visual field
Relay vision information to neurons innervating the MUSCLES THAT CONTROL EYE MOVEMENT
Inferior colliculi (auditory relay nuclei)
Relaying …. information from hearing receptors of the ear to the …..
Act in …… responses to sound
Inferior colliculi (auditory relay nuclei)
Relaying AUDITORY information from hearing receptors of the ear to the SENSORY CORTEX
Act in REFLEXIVE responses to sound
Midbrain - Substantia Nigra
Located … to the cerebral peduncle
Contains …. (biochemically related to dopamine)
Functionally linked to ….
….. Disease
Midbrain - Substantia Nigra
Located ABOVE to the cerebral peduncle
Contains MELANIN PIGMENT (biochemically related to dopamine)
Functionally linked to BASAL NUCLEI/GANGLIA
DOPAMINE NEURONE DEGENERATION PARKINSONS Disease
Midbrain - Red Nucleus
Lies above the …
Rich bloody supply & contains ….
Relay nucleus in some ….
Midbrain - Red Nucleus
Lies above the SUBSTANTIA NIGRA
Rich bloody supply & contains IRON PIGMENT
Relay nucleus in some DESCENDING MOTOR PATHWAYS
Midbrain - Superior Cerebullar Peduncle
Comprises fibres that connect …. with ….
Major ….. fibres from the ….
Involved in ….
Midbrain - Superior Cerebullar Peduncle
Comprises fibres that connect CEREBELLUM with MIDBRAIN
Major OUTPUT fibres from the CEREBELLUM
Involved in PROPRIOCEPTION
Pons
Structures:
Pons
Structures:
- Cranial nerves
- trigeminal (V)
- abducens (VI)
- facial (VII)
- vestibulocochlear (VIII)
- 4th ventricle
- Middle cerebellar peduncle
Pons (bridge)
Composed of both … & …. tracts
Pomposed of various pontine nuclei: eg …
Pons (bridge)
Composed of both ASCENDING SENSORY & DESCENDING MOTOR tracts
Pomposed of various pontine nuclei: eg PNEUMOTAXIC CENTRE (RESPIRATORY CENTRE)
Pons - Middle Cerebellar Peduncle
Comprises fibres from the … to the …
Convey …. and …. command information
Pons - Middle Cerebellar Peduncle
Comprises fibres from the PONS to the CEREBELLUM
Convey MOTOR and SENSORY command information
Medulla
Structures:
Medulla
Structures:
- Pyramids
- Olives
- Gracile & Cuneate Tubercles
- Cranial nerves
- glossopharyngeal (IX)
- vagus (X)
- accessory (XI)
- hypoglossal (XII)
- 4th ventricle
- Inferior cerebellar peduncle
Medulla - Pyramids
Pyramids (open medulla)
formed by the large …. descending from the …
Pyramidal Decussation (closed medulla) axons of the ….. cross over to the opposite side at the level just above the ….
Medulla - Pyramids
Pyramids (open medulla)
formed by the large PYRAMIDAL (coricospinal) TRACTS descending from the MOTOR CORTEX
Pyramidal Decussation (closed medulla) axons of the PYRAMIDAL TRACTS cross over to the opposite side at the level just above the MEDULLA SPINAL JUNCTION
Medulla - Olives
Located in the …
Contains …. which relay sensory information to the …
Medulla - Olives
Located in the OPEN MEDULLA
Contains INFERIOR OLIVARY which relay sensory information to the CEREBELLUM
Medulla - Tubercles
Cuneate and Gracile tubercles (in closed medulla) receive …. from …. & …. from the upper and lower body respectively
Medulla - Tubercles
Cuneate and Gracile tubercles (in closed medulla) receive SOMATOSENSORY INFORMATION from CUNEATE FASCICULUS & GRACILE FASCICULUS SPINAL TRACTS from the upper and lower body respectively
Medulla - Inferior Cerebellar Peduncle
Comprises fibres to and from the …. to …
Carries … and …. important for … and …
Medulla - Inferior Cerebellar Peduncle
Comprises fibres to and from the MEDULLA/SPINAL CORD to CEREBELLUM
Carries SENSORY and MOTOR INFORMATION important for BALANCE and POSTURE
Reticular Formation
Composed of clusters of …. scattered throughout …
Covering the arousal of the brain via ….
Reticular Formation
Composed of clusters of GREY MATTER scattered throughout MIDBRAIN, PONS, AND MEDULLA
Covering the arousal of the brain via THALAMUS
Reticular Formation
Involved in …
Inhibited by …. located in the …
Depressed by …
Brainstem injury:
Reticular Formation
Involved in HABITUATION
Inhibited by SLEEP CENTRES located in the HYPOTHALAMUS & OTHER BRAIN REGIONS
Depressed by ALCOHOL, SLEEP-INDUCING DRUGS & TRANQUILISERS
Brainstem injury:
- permanent unconsciousness
Cranial Nerves
name them
- L6, page 3
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A way of learning the Cranial Nerves
- L6, page 34
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Olfactory Nerves
…. sensory nerves
Run from the nasal mucosa, pass through … of ethmoid bone to synapse w/ the …
Provide …
Damage causes ….
Olfactory Nerves
TINY sensory nerves
Run from the nasal mucosa, pass through CRIBIFORM PLATE of ethmoid bone to synapse w/ the OLFACTORY BULB
Provide SENSE OF SMELL
Damage causes IMPAIRED SENSE OF SMELL (ANOSMIA)
Olfactory Projection Pathways:
- L6, page 39
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Optic nerves
Axons arising from the …. of the eye to form …
Each optic nerve passes through its … of the orbit
Nerves converge to form the … (axons partially cross over) & continue on as …
Enables …
Optic nerves
Axons arising from the RETINA of the eye to form OPTIC NERVE
Each optic nerve passes through its OPTIC FORAMEN of the orbit
Nerves converge to form the OPTIC CHIASM (axons partially cross over) & continue on as OPTIC TRACTS
Enables VISION
Visual Processing: 1) Retina Processing
Steps:
Visual Processing: 1) Retina Processing
Steps:
Local currents produce in response to light
Rods & Cones > Bipolar neurons > Ganglion cells > Optic nerve > Subcortical & cortical visual areas
Visual Processing
Each nasal retina sees a …
Each temporal retina sees …
Left side of each retina sees the ….
Right side of each retina sees the …
Visual Processing
Each nasal retina sees a TEMPORAL VISUAL FIELD/WORLD
Each temporal retina sees NASAL VISUAL FIELD/WORLD
Left side of each retina sees the RIGHT VISUAL FIELD/WORLD
Right side of each retina sees the LEFT VISUAL FIELD/WORLD
VIsual processing
Optic Tract: Crossed axons from …. & uncrossed axons from …
VIsual processing
Optic Tract: Crossed axons from NASAL RETINA & uncrossed axons from TEMPORAL RETINA
L7 learning objectives
- Identify the location of each cranial nerve root in the brainstem
- Describe the origin, course and major function of each cranial nerve
- Understand the physical consequences of damage to each cranial nerve
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Cranial nerves
L7, page 4
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Oculomotor Nerves
Axons extend from … & pass through the … to the …
Oculomotor Nerves
Axons extend from VENTRAL MIDBRAIN & pass through the SUPERIOR ORBITAL FISSURE to the EYE
III. Oculomotor Nerves: Somatic (voluntary) motor axons
to … of the 6 extrinsic eye muscles - move …
to … superior muscle - raising …
III. Oculomotor Nerves: Somatic (voluntary) motor axons
to 4 of the 6 extrinsic eye muscles - move EYEBALL
to LEVATOR PALPEBRAE superior muscle - raising UPPER EYELID
III. Oculomotor Nerves: Parasympathetic (autonomic) motor axons
to … muscles of … - causing pupil to …
to … muscle - controlling shape of … for visual focusing
III. Oculomotor Nerves: Parasympathetic (autonomic) motor axons
to CONSTRICTOR muscles of IRIS - causing pupil to CONSTRICT
to CILIARY muscle - controlling shape of LENS for visual focusing
III. Oculomotor Nerves
In sum: provides most of the … of each eye
ALSO:
III. Oculomotor Nerves
In sum: provides most of the MOVEMENT of each eye
ALSO:
- Opening of eyelid
- Constriction of pupil
- Focusing
IV. Trochlear Nerves
Axons emerge from …., course ventrally around midbrain, pass through the … to the …
IV. Trochlear Nerves
Axons emerge from DORSAL MIDBRAIN, course ventrally around midbrain, pass through the SUPERIOR ORBITAL FISSURE to the EYE
IV. Trochlear Nerves
Provide …
Damage causes … & inability to rotate eye …
IV. Trochlear Nerves
Provide EYE MOVEMENT
Damage causes DOUBLE VISION & inability to rotate eye INFEROLATERALLY
V. TRIGEMINAL NERVES
Axons extend from … & ….
Cell bodies of sensory neurons are located in large …
V. TRIGEMINAL NERVES
Axons extend from FACE TO PONS & PONS TO MUSCLES
Cell bodies of sensory neurons are located in large TRIGEMINAL GANGLION
V. Trigeminal Nerve
Axons run from … via …
Convey …. from skin of anterior scalp, upper eyelid & nose, & from nasal cavity mucosa, cornea & lacrimal (tear) gland
V. Trigeminal Nerve
Axons run from FACE TO PONS via SUPERIOR ORBITAL FISSURE
Convey SENSORY IMPULSES from skin of anterior scalp, upper eyelid & nose, & from nasal cavity mucosa, cornea & lacrimal (tear) gland
V. Trigeminal Nerves: Mandibular division (V3) SENSORY BRANCH
Axons pass through skull via …
Convey …. from anterior tongue (except taste bud), lower teeth, skin of chin, & temporal region of scalp
V. Trigeminal Nerves: Mandibular division (V3)
Axons pass through skull via FORAMEN OVALE
Convey SENSORY IMPULSES from anterior tongue (except taste bud), lower teeth, skin of chin, & temporal region of scalp
V. Trigeminal Nerves: Mandibular division (V3) MOTOR BRANCH
Supply …. to (carry proprioceptor axons from) muscles of mastication
V. Trigeminal Nerves: Mandibular division (V3) MOTOR BRANCH
Supply MOTOR AXONS to (carry proprioceptor axons from) muscles of mastication
V. Trigeminal Nerves
…. cranial nerve
….. (transmitting afferent impulses from touch, temperature & pain receptors)
Supply motor axons to …
… produces loss of sensation & impaired chewing
V. Trigeminal Nerves
LARGEST cranial nerve
MAIN SENSORY NERVE TO FACE (transmitting afferent impulses from touch, temperature & pain receptors)
Supply motor axons to MUSCLES OF MASTICATION
DAMAGE produces loss of sensation & impaired chewing
VI. Abducens Nerves
Axons leave … & pass through … to … (lateral rectus muscle)
Provide … (abducts the eyeball)
… results in inability to rotate eye laterally & at rest eye rotates medially
VI. Abducens Nerves
Axons leave INFERIOR PONS & pass through SUPERIOR ORBITAL FISSURE to EYE (lateral rectus muscle)
Provide EYE MOVEMENT (abducts the eyeball)
DAMAGE results in inability to rotate eye laterally & at rest eye rotates medially
VII. Facial Nerves
Axons emerge from …, enter temporal bone via … and run w/in bone (through inner ear cavity) before emerging through styloid foramen; course to …
VII. Facial Nerves
Axons emerge from PONS enter temporal bone via INTERNAL AUDITORY MEATUS and run w/in bone (through inner ear cavity) before emerging through styloid foramen; course to LATERAL ASPECT OF FACE
VII. Facial Nerves
Major …
Supply motor axons to (convey proprioceptor impulses from) skeletal muscles of face (….) Except for chewing muscles served by cranial nerve V
Transmit … impulses to lacrimal (tear) glands, nasal & salivary glands
Convey …. of anterior 2/3 of tongue
… Produces sagging facial muscles & disturbed sense of taste (missing sweet, salty & umami)
VII. Facial Nerves
Major MOTOR AXONS OF FACE
Supply motor axons to (convey proprioceptor impulses from) skeletal muscles of face (MUSCLES OF FACIAL EXPRESSION) Except for chewing muscles served by cranial nerve V
Transmit PARASYMPATHETIC (AUTONOMIC) MOTOR impulses to lacrimal (tear) glands, nasal & salivary glands
Convey SENSORY IMPULSES FROM TASTE BUDS of anterior 2/3 of tongue
DAMAGE produces sagging facial muscles & disturbed sense of taste (missing sweet, salty & umami)
VII. Facial Nerves - Bells Palsy
Characterised by … (affected side) & ….
… Causing inflammation of facial nerve
….: Lower eyelid droops, corner of mouth sags, tears drip continuously, eye cannot be completely closed, paralysed face is ‘pulled’
…: Steroids, rest
VII. Facial Nerves - Bells Palsy
Characterised by PARALYSIS OF FACIAL MUSCLES (affected side) & PARTIAL LOSS OF TASTE SENSATION
VIRAL INFECTION causing inflammation of facial nerve
Symptoms: Lower eyelid droops, corner of mouth sags, tears drip continuously, eye cannot be completely closed, paralysed face is ‘pulled’
Treatment: Steroids, rest
VIII. Vestibulocochlear Nerves
Axons arising from hearing & equilibrium apparatus w/in …., passing through … to enter …
VIII. Vestibulocochlear Nerves
Axons arising from hearing & equilibrium apparatus w/in INNER EAR OF TEMPORAL BONE, passing through INTERNAL ACOUSTIC MEATUS to enter BRAINSTEM AT THE PONS-MEDULLA BORDER
VIII. Vestibulocochlear Nerves
Provide … (cochlea nerves) and sense of … (vestibular nerves
…. produces
- Deafness
- Dizziness, nausea
- Loss of balance
- Vestibular nystagmus (rapid involuntary eye movements)
VIII. Vestibulocochlear Nerves
Provide HEARING (cochlea nerves) and sense of BALANCE (vestibular nerves
DAMAGE produces
- Deafness
- Dizziness, nausea
- Loss of balance
- Vestibular nystagmus (rapid involuntary eye movements)
Temporal Lobe - Primary Auditory Cortex
…. (inside lateral fissure) extending to superior margin of the ….
Processes ….
…. = hearing loss
….. = cortical deafness
Temporal Lobe - Primary Auditory Cortex
TRANSVERSE TEMPORAL GYRUS (inside lateral fissure) extending to superior margin of the SUPERIOR TEMPORAL GYRUS
Processes AUDITORY INFO
UNILATERAL DAMAGE (MIDDLE CEREBRAL ARTERY) = hearing loss
BILATERAL DAMAGE = cortical deafness
IX. Glossopharyngeal Nerves
Axons emerge from …. & leave skull through …
IX. Glossopharyngeal Nerves
Axons emerge from MEDULLA & leave skull through JUGULAR FORAMEN
IX. Glossopharyngeal Nerves
Supply … axons to (carry proprioceptor fibres from) a …. - stylopharyngeus
Provide …. to parotid ….
IX. Glossopharyngeal Nerves
Supply MOTOR axons to (carry proprioceptor fibres from) a PHARYNGEAL MUSCLE- stylopharyngeus
Provide PARASYMPATHETIC MOTOR AXONS to parotid SALIVARY GLAND
IX. Glossopharyngeal Nerves
Sensory axons conduct …. from … & posterior 1/3 of …
Conducts sensory impulses from …. in the … & … of …
IX. Glossopharyngeal Nerves
Sensory axons conduct TASTE & GENERAL SENSORY IMPULSES from PHARYNX & posterior 1/3 of TONGUE
Conducts sensory impulses from CHEMORECEPTORS in the CAROTID BODY & PRESSURE RECEPTORS of CAROTID SINUS
IX. Glossopharyngeal Nerves
Provide control over …. from posterior 1/3 of tongue, control of …
… results in loss of bitter & sour taste & impaired swallowing
IX. Glossopharyngeal Nerves
Provide control over SWALLOWING, SALIVATION, GAGGING, SENSATION from posterior 1/3 of tongue, control of BLOOD PRESSURE & RESPIRATION
DAMAGE results in loss of bitter & sour taste & impaired swallowing
X. Vagus Nerve
Axons emerge from …, pass through skull via … descend through neck region into …
X. Vagus Nerve
Axons emerge from MEDULLA, pass through skull via JUGULAR FORAMEN, descend through neck region into THORAX & ABDOMEN
X. Vagus Nerves
Motor:
- Supply motor axons to (carry proprioceptor fibres from) skeletal muscles of …
- Parasympathetic (autonomic) motor fibres supply … & …
Sensory:
- Conduct sensory impulses from .. & …
- Transmit sensory impulses from … in the … & … & …. of ….
- Conduct sensory impulses from … of posterior tongue & pharynx
X. Vagus Nerves
Motor:
- Supply motor axons to (carry proprioceptor fibres from) skeletal muscles of PHARYNX & LARYNX
- Parasympathetic (autonomic) motor fibres supply HEART, LUNGS & ABDOMINAL VISCERA
Sensory:
- Conduct sensory impulses from THORACIC & ABDOMINAL VISCERA
- Transmit sensory impulses from CHEMORECEPTORS in the CAROTID & AORTIC BODIES & PRESSURE RECEPTORS of CAROTID SINUS
- Conduct sensory impulses from TASTE BUDS of posterior tongue & pharynx
X. VAGUS NERVES
The only cranial nerve extending beyond the head & neck to the … & …
Majority of motor axons are …
Provide … & …; regulate activities of …
…. causes hoarseness or loss of voice, impaired swallowing & digestive system mobility
…. implicated in hypertension, anxiety disorders & depression
X. VAGUS NERVES
The only cranial nerve extending beyond the head & neck to the THORAX & ABDOMEN
Majority of motor axons are PARASYMPATHETIC (AUTONOMIC)
Provide SWALLOWING & SPEECH; regulate activities of MAJOR VISCERA
DAMAGE causes hoarseness or loss of voice, impaired swallowing & digestive system mobility
HYPOACTIVITY implicated in hypertension, anxiety disorders & depression
XI Accessory Nerves
… root joins with axons of vagus nerve (X) to supply motor axons to …, … & …;
…. causes hoarseness or loss of voice & impaired swallowing
…. roots supplies motor axons to trapezius & sternocleidomastoid muscles, therefore provides …….
… causes impaired head, neck & shoulder movement eg unable to shrug on one side if unilateral injury
XI Accessory Nerves
CRANIAL root joins with axons of vagus nerve (X) to supply motor axons to LARYNX, PHARYNX & SOFT PALATE
DAMAGE causes hoarseness or loss of voice & impaired swallowing
SPINAL roots supplies motor axons to trapezius & sternocleidomastoid muscles, therefore provides HEAD, NECK & SHOULDER MOVEMENTS
DAMAGE causes impaired head, neck & shoulder movement eg unable to shrug on one side if unilateral injury
XII. Hypoglossal Nerves
Axons arise by a series of roots from …, exit from skull via …. to …
Axons emerge b/w the …
XII. Hypoglossal Nerves
Axons arise by a series of roots from MEDULLA, exit from skull via HYPOGLOSSAL CANAL to TONGUE
Axons emerge b/w the PYRAMID & OLIVE
XII. Hypoglossal Nerves
Supply somatic motor axons to muscles of …
Provide …. of speech, food manipulation & swallowing
… causes dificulties in speech & swallowing
- Both sides - inabiluty to protrude tongue
- One side - tongue deviates (leans) toward injured side & eventually results in ipsilateral atrophy
XII. Hypoglossal Nerves
Supply somatic motor axons to muscles of TONGUE
Provide TONGUE MOVEMENTS of speech, food manipulation & swallowing
DAMAGE causes dificulties in speech & swallowing
- Both sides - inabiluty to protrude tongue
- One side - tongue deviates (leans) toward injured side & eventually results in ipsilateral atrophy
Cerebellum
Consist of …, …. & ….
40 x more ….. than …
very …. structure
concerned primarily with:
- ….., precisely timed movement
- control of …
- maintenance of …
Receives vast amount of sensory info, but does not give rise to …. …. perceptions
Cerebellum
Consist of CORTEX, WHITE MATTER & DEEP NUCLEI
40 x more AFFERENT than EFFERENT
very ORDERED structure
concerned primarily with:
- SYNCHRONISED, precisely timed movement
- control of MUSCLE TONE (posture)
- maintenance of BALANCE
Receives vast amount of sensory info, but does not give rise to CONSCIOUS SENSORY perceptions
External Cerebellum (superior surface)
Right and left hemispheres connected by …
Parallel surface folds called … are grey matter
External Cerebellum (superior surface)
Right and left hemispheres connected by VERMIS
Parallel surface folds called FOLIA are grey matter
Cerebellar Lobes
Anterior & posterior lobes co-ordinate ….
Cerebellar Lobes
Anterior & posterior lobes co-ordinate MOVEMENT
Flocculonodular lobe helps with ….
Flocculonodular lobe helps with BALANCE
Cerebellum: Sagittal Sub-Divisions
What are the zones?
Cerebellum: Sagittal Sub-Divisions
What are the zones?
- Lateral zone
- Intermediate zone
Spinocerebellum (vermis & intermediate zone):
Receives … information
Regulates … via …
Spinocerebellum (vermis & intermediate zone):
Receives PROPRIOCEPTIVE information
Regulates BODY MOVEMENTS via ERROR CORRECTION
Cerebrocerebellum (lateral zone):
Receives input from the …. and … ….., outputs to the … and … …..
…. movements and motor learning
Coordination of …
Important in …… …. movements
Cerebrocerebellum (lateral zone):
Receives input from the PONS and CEREBRAL CORTEX, outputs to the THALAMUS and RED NUCLEUS
PLANNING movements and motor learning
Coordination of MUSCLES
Important in VISUALLY GUIDED movements
Vestibullocerebellum (flocculonodular lobe):
Receives inputs from the …. system, sends outputs back to the …. ….
Controlling …
…. reflexes
Vestibullocerebellum (flocculonodular lobe):
Receives inputs from the VESTIBULAR system, sends outputs back to the VESTIBULAR NUCLEI
Controlling BALANCE
OCULAR (eye) reflexes
Three major components:
Three major components:
- Superficial gray matter (cortex)
- White matter)
- Deep nuclei (gray mattey)
What makes up the Deep Cerebellar Nuclei?
What makes up the Deep Cerebellar Nuclei?
- Fastigial
- Interposed
- Dentate
Cerebellar Cortex - Circuity
Two main inputs:
…. from spinal cord or brainstem neurons conveying motor or sensory input
….. mainly from inf. olivary nucleus = proprioceptive input
…. … form excitatory synapses with … …. in the cerebellar cortex
The …. …. send their axon as a ‘parallel fibre’ to form exitatory synapses with the …. neurons
Cerebellar Cortex - Circuity
Two main inputs:
MOSSY FIBRES from spinal cord or brainstem neurons conveying motor or sensory input
CLIMBING FIBRES mainly from inf. olivary nucleus = proprioceptive input
MOSSY AXONS form excitatory synapses with GRANULE NEURONS in the cerebellar cortex
The GRANULE NEURONS send their axon as a ‘parallel fibre’ to form exitatory synapses with the PURKINJE neurons
Cerebellar Cortex - Circuitry
Climbing axons form …. synapses directly with the …. …. in the …. ….
…. neurons are the sole output of the cerebellar cortex
- Inhibitory - synapse in … …. ….
- Work with input axons to regulate … …. and …. of the neurons in the deep cerebellar nuclei
Cerebellar Cortex - Circuitry
Climbing axons form EXCITATORY synapses directly with the PURKINJE NEURONS in the CEREBELLAR CORTEX
PURKINJE neurons are the sole output of the cerebellar cortex
- Inhibitory - synapse in DEEP CEREBELLAR NUCLEI
- Work with input axons to regulate FIRING FREQUENCY and AMPLITUDE of the neurons in the deep cerebellar nuclei
Draw Cerebellar Cortex Circuity
- L8, Page 29
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Cerebellar Peduncles
Inferior Cerebellar Peduncle (Medulla)
Conveys …. information to the cerebellum
- From ….. proprioceptors throughout the body
- From the … …. of the brainstem (equilibrium & balance)
Contains both …. & … axons
Cerebellar Peduncles
Inferior Cerebellar Peduncle (Medulla)
Conveys SENSORY information to the cerebellum
- From MUSCLE proprioceptors throughout the body
- From the VESTIBULAR NUCLEI of the brainstem (equilibrium & balance)
Contains both AFFERENT & EFFERENT axons
Cerebellar Peduncles
Middle Cerebellar Peduncle (Pons)
Contains only …. axons (crossed axons from …. …. ….)
Cerebellar Peduncles
Middle Cerebellar Peduncle (Pons)
Contains only AFFERENT axons (crossed axons from CONTRALATERAL PONTINE NUCLEI)
Cerebellar Peduncles
Superior Cerebellar Peduncle (Midbrain)
Formed by axons that arise from … …. … (main …. pathway)
- Fibres decussate at various levels - either terminate in the … ….. or continue rostrally to end w/in the … (then to … … ….)
Cerebellar Peduncles
Superior Cerebellar Peduncle (Midbrain)
Formed by axons that arise from DEEP CEREBELLAR NUCLEI (main EFFERENT pathway)
- Fibres decussate at various levels - either terminate in the RED NUCLEUS or continue rostrally to end w/in the THALAMUS (then to CEREBRAL MOTOR CORTEX)
Cerebrocerebellar Ciruit (Lateral Zone)
Dentate nucleus receives …. information from …. …. …., …. …. & …..
- Input to the … …. & … ….
Controls …. movements of …, And contributes to … ….
Cerebrocerebellar Ciruit (Lateral Zone)
Dentate nucleus receives SENSORIMOTOR information from LATERAL CEREBELLAR CORTEX, CEREBRAL CORTEX & PONS
- Input to the VENTROLATERAL THALAMUS & RED NUCLEUS
Controls MULTI-JOINTED movements of LIMBS, and contributes to MOTOR PLANNING
Spinocerebellar Circuit
Fastigial nucleus receives …… information from … …. …. & …
- Input to … … & … ….
Controls … via influencing axial muscles in ….
Spinocerebellar Circuit
Fastigial nucleus receives SOMATOSENSORY information from VERMAL CEREBELLAR CORTEX & TRUNK
- Input to VESTIBULAR NUCLEI & RETICULAR FORMATION
Controls POSTURE via influencing axial muscles in TRUNK
Spinocerebellar Circuit (Intermediate Zone)
Interposed nuclei receive ….. information from … … …. & ….
- Inputs to the … …
Controls … … … … (precision of movements at joints)
Spinocerebellar Circuit (Intermediate Zone)
Interposed nuclei receive SOMATOSENSORY information from INTERMEDIATE CEREBELLAR CORTEX & LIMBS
- Inputs to the RED NUCLEUS
Controls ACCURACY OF LIMB MOVEMENTS (precision of movements at joints)
Vestibulocerebellar Circuit (Flocculonodular Lobe)
Flocculonodular lobe receives …. information
- Input to the ….
Controls ….
Vestibulocerebellar Circuit (Flocculonodular Lobe)
Flocculonodular lobe receives VESTIBULAR information
- Input to the VESTIBULAR NUCLEI
Controls BALANCE
Match up the Cerebellar Structures
L8, page 39
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How is synergistic multijoint movement achieved?
At the same time, the cerebellum receives information from proprioceptors … … …, as well as … & ….. input
How is synergistic multijoint movement achieved?
At the same time, the cerebellum receives information from proprioceptors THROUGHOUT THE BODY, as well as VISUAL & VESTIBULAR input
L9 Learning objectives
- Identify cortical regions involved in processing special and general senses
- Classify the different sensory receptors based on function, location & complexity
- Explain the structure of different general sensory receptors
- Identify and describe the ascending somatosensory pathways, their functions, and the consequence of damage to each pathway
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Sensation
….. of sensory stimulus
Stimulus = change in the …. or …. environment
Perceptions
….. of the meanings of the sensory stimuli
Both sensation & perception occur in the ….
Sensation
DETECTION of sensory stimulus
Stimulus = change in the EXTERNAL or INTERNAL environment
Perceptions
INTERPRETATION of the meanings of the sensory stimuli
Both sensation & perception occur in the BRAIN
Special Senses
Each special sense organ projects to a specialized region of the brain. In the cerebrum, specialized region is called a .. … …
Taste - lower end of … ….
Smell - medial …. & ….. lobes
Vision ….. lobe
Hearing - ….. temporal gyri/ ….. temporal gyri
Equilibrium - mainly to the …
Special Senses
Each special sense organ projects to a specialized region of the brain. In the cerebrum, specialized region is called a PRIMARY SENSORY CORTEX
Taste - lower end of POSTCENTRAL GYRUS
Smell - medial TEMPORAL & ORBITOFRONTAL lobes
Vision OCCIPITAL lobe
Hearing - SUPERIOR temporal gyri/ TRANSVERSE temporal gyri
Equilibrium - mainly to the CEREBELLUM
Sensory Receptors
- Are specialized to respond to …. in their ….
Classified by:
- the type of …. they detect
- their body ….
- their structural ….
Sensory Receptors
- Are specialized to respond to CHANGES in their ENVIRONMENT
Classified by:
- the type of STIMULUS they detect
- their body LOCATION
- their structural COMPLEXITY
Classification of Sensory Receptors by Stimulus Type
1) Mechanoreceptors
- Are sensitive to a …. ….
(eg touch, pressure, vibration, stretch, itch)
2) Thermoreceptors
- Are sensitive to ….. changes
3) Photoreceptors
- Respond to …. …. (the retina of the eye)
4) Chemoreceptors
- Respond to …. in solution (molecules smelt or tasted, or changes in blood chemistry)
5) Nociceptors (noci = harm)
- Respond to potentially …. …. that result in pain
Classification of Sensory Receptors by Stimulus Type
1) Mechanoreceptors
- Are sensitive to a MECHANICAL FORCE
(eg touch, pressure, vibration, stretch, itch)
2) Thermoreceptors
- Are sensitive to TEMPERATURE changes
3) Photoreceptors
- Respond to LIGHT ENERGY (the retina of the eye)
4) Chemoreceptors
- Respond to CHEMICALS in solution (molecules smelt or tasted, or changes in blood chemistry)
5) Nociceptors (noci = harm)
- Respond to potentially DAMAGING STIMULI that result in pain
Classification of Sensory Receptors by Location
1) Exteroceptors
- are sensitive to stimuli arising …. the body
- are located …. or … the body surface
- include:
- touch, pressure, pain & temperature receptors
- receptors of special senses (VIsion, hearing)
2) Interoceptors or Visceroceptors
- are sensitive to stimuli ….. the body
- are located in the …. …. & … ….
(eg chemical changes, tissue stretch, temperature)
Classification of Sensory Receptors by Location
1) Exteroceptors
- are sensitive to stimuli arising OUTSIDE the body
- are located NEAR or AT the body surface
- include:
- touch, pressure, pain & temperature receptors
- receptors of special senses (VIsion, hearing)
2) Interoceptors or Visceroceptors
- are sensitive to stimuli WITHIN the body
- are located in the VISCERAL ORGANS & BLOOD VESSELS
(eg chemical changes, tissue stretch, temperature)
Proprioceptors
- Are sensitive to …. stimuli
- Located in … ….., …., …., …… & in ….. …. coverings of bones & muscles
- …… receptors of the inner ear are sometimes included in this class
- Constantly advise the brain of the body’s …. & …. in ….
Proprioceptors
- Are sensitive to …. stimuli
- Located in SKELETAL MUSCLES, TENDONS, JOINTS, LIGAMENTS & in CONNECTIVE TISSUE coverings of bones & muscles
- EQUILIBRIUM receptors of the inner ear are sometimes included in this class
- Constantly advise the brain of the body’s MOVEMENT & LOCATION in SPACE
Classification of Sensory Receptors by Structural Complexity
Complex Receptors of the special senses are located in …. …. …. (eg rods & cones of retina)
Simple Receptors of the general senses:
- Tactile sensation
- Temperature
- Pain
- Muscle sense
Anatomically, these receptors are either ….. …. endings or ….. ….. endings
Classification of Sensory Receptors by Structural Complexity
Complex Receptors of the special senses are located in SPECIAL SENSE ORGANS (eg rods & cones of retina)
Simple Receptors of the general senses:
- Tactile sensation
- Temperature
- Pain
- Muscle sense
Anatomically, these receptors are either FREE NERVE endings or ENCAPSULATED NERVE endings
Free (Unencapsulated) Nerve Endings
Widely present dendrites forming small knoblike swellings, respond mainly to .. & …. (also overt pressure)
Modified free nerve endings, respond to …. ….
Free (Unencapsulated) Nerve Endings
Widely present dendrites forming small knoblike swellings, respond mainly to PAIN & TEMPERATURE (also overt pressure)
Modified free nerve endings, respond to …. ….
Tactile Corpuscles (Meissners Corpuscles)
- Numerous in …., …. & soles of the …
- …. …. & …..
Tactile Corpuscles (Meissners Corpuscles)
- Numerous in NIPPLES, FINGERTIPS & soles of the FEET
- LIGHT TOUCH & TEXTURE
Lamellated Corpuscles (pacinian Corpuscles)
- …. tissue of the skin
- … …., …., …. & ….
Lamellated Corpuscles (pacinian Corpuscles)
- SUBCUTANEOUS tissue of the skin
- DEEP PRESSURE, STRETCH, TICKLE & VIBRATION
Ruffini Corpuscles
- …, …. tissue & … capsules
- …. ….. & ….
Ruffini Corpuscles
- DERMIS, SUBCUTANEOUS tissue & JOINT capsules
- DEEP PRESSURE & STRETCH
Muscle Spindles
- W/in … ….
- Each consist of a bundle of … skeletal muscle fibres in a … …. ….
- … …. (proprioception)
Muscle Spindles
- W/in SKELETAL MUSCLES
- Each consist of a bundle of MODIFIED skeletal muscle fibres in a CONNECTIVE TISSUE CAPSULE
- MUSCLE STRETCH (proprioception)
Encapsulated nerves Endings: Joint Kinesthetic Receptors
- Are …… that monitor stretch in the articular capsules that enclose synovial joints
- Contribute to … …..
Encapsulated nerves Endings: Joint Kinesthetic Receptors
- Are PROPRIOCEPTORS that monitor stretch in the articular capsules that enclose synovial joints
- Contribute to CONSCIOUS PROPRIOCEPTION
Ascending Somatosensory Exteroception & Proprioception Systems
Recieves input from ….. & ……
….. …. - …. ….. Pathway
- fine touch, vibration & conscious proproiception = fin discrimination
……. Pathways
- Pain, temperature, crude touch & pressure
- … & …. Pathways
…. Pathways
- unconscious proprioception
Ascending Somatosensory Exteroception & Proprioception Systems
Recieves input from EXTEROCEPTORS & PROPRIOCEPTORS
DORSAL COLUMNS - MEDIAL LEMNISCUS PATHWAY Pathway
- fine touch, vibration & conscious proproiception = fin discrimination
SPINOTHALAMIC Pathways
- Pain, temperature, crude touch & pressure
- ANTERIOR & LATERAL Pathways
SPINOCEREBELLAR Pathways
- unconscious proprioception
General Organzation of Somatosensory Systems
3) Cerebral neural circuits
- – order neurons
2) Ascending pathways
…. order neurons
1) Sensory receptors
…. order neurons
General Organzation of Somatosensory Systems
3) Cerebral neural circuits THIRD order neurons
2) Ascending pathways
SECOND order neurons
1) Sensory receptors
FIRST order neurons
1) Processing at the Receptor Level
Propagation
- generating … … to the …. …./ …..
Transduction
- Converting …. …. into changes in membrane potential in … axons
Receptors
- Detecting ….
1) Processing at the Receptor Level
Propagation
- generating NERVE IMPULSES to the SPINAL CORD/ MEDULLA
Transduction
- Converting STIMULUS ENERGY into changes in membrane potential in SENSORY axons
Receptors
- Detecting STIMULI
Processing at the Circuit level
Ascending Sensory Pathways
- Impulses delivered to the appropriate regions of the ….
- OR impulses delivered to the ……
Processing at the Circuit level
Ascending Sensory Pathways
- Impulses delivered to the appropriate regions of the THALAMUS
- OR impulses delivered to the CEREBRUM
3) Processing at the Perceptual Level
- ….. of sensory input
3) Processing at the Perceptual Level
- INTERPRETATION of sensory input
Dorsal Column - Medial Lemniscus Pathway
…. carries impulses from lower limbs & inferior body trunk
…. transmits afferent impulses from upper limbs, trunk & neck
Dorsal Column - Medial Lemniscus Pathway
GRACILE TRACT carries impulses from lower limbs & inferior body trunk
CUNEATE TRACT transmits afferent impulses from upper limbs, trunk & neck
Comparing Cross-section of Spinal Cord
….. …. increases in dorsal columns from lumbar to cervical regions
- reflects increasing addition of …. fibres from caudal to rostral truck regions
Comparing Cross-section of Spinal Cord
WHITE MATTER increases in dorsal columns from lumbar to cervical regions
- reflects increasing addition of SENSORY fibres from caudal to rostral truck regions
Cuneate & Gracile tubercles (in closed medulla) receive …… information from ….. ….. & ….. ….. spinal tracts, from the upper and lower body respectively
Cuneate & Gracile tubercles (in closed medulla) receive SOMATOSENSORY information from CUNEATE FASCICULUS & GRACILE FASCICULUS spinal tracts, from the upper and lower body respectively
Spinothalamic Pathways
Lateral Spinothalamic Pathway
- Transmits impulses with … & … to opposite somatosensory cortex
Anterior Spinothalamic Pathway
- Transmits impulses concerned with … … & …. to opposite somatosensory cortex
Spinothalamic Pathways
Lateral Spinothalamic Pathway
- Transmits impulses with PAIN & TEMPERATURE to opposite somatosensory cortex
Anterior Spinothalamic Pathway
- Transmits impulses concerned with CRUDE TOUCH & PRESSURE to opposite somatosensory cortex
Spinocerebellar Pathways
Transmit information about muscle or tendon stretch to the ….. ….., which use this information to coordinate skeletal muscle activity
Responsible for …. …..
Spinocerebellar Pathways
Transmit information about muscle or tendon stretch to the IPSILATERAL CEREBELLUM, which use this information to coordinate skeletal muscle activity
Responsible for UNCONSCIOUS PROPRIOCEPTION
Somatosensory pathways
Fill in the table
- L9, page 45
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L10 objectives
- Explain the hierarchy of motor control
- Describe the descending motor tracts (pyramidal and extrapyramidal) and their functions
- Explain the consequences of pyramidal tract damage
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Hierarchy of Motor Control
Highest:
…, …. & …..
- …. level
- ….. level
Middle
…. & ….
- ….. level
Lowest
….
- ….. level
Hierarchy of Motor Control
Highest:
PRE-MOTOR CORTEX, BASAL GANGLIA & CEREBELLUM
- PRECOMMAND level
- PRE-ACTION level
Middle
PRIMARY MOTOR CORTEX & BRAINSTEM
- PROJECTION level
Lowest
SPINAL CORD
- SEGMENTAL level
General organisation of the Motor System
- L10, page 5
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1) Precommand Level - Programs & Instructions
Includes the … …., …. & … ….
…… responsible for initiating plan for next intended movement
- Innervates … …. to release brake to start a specific movement
- Innervates … which precisely calculates the best way to achieve coordinated synergistic movements across multiple limb joints - also monitors muscle … & ….
1) Precommand Level - Programs & Instructions
Includes the PREMOTOR CORTEX, CEREBELLUM & BASAL GANGLIA
PREMOTOR CORTEX responsible for initiating plan for next intended movement
- Innervates BASAL GANGLIA to release brake to start a specific movement
- Innervates CEREBELLUM which precisely calculates the best way to achieve coordinated synergistic movements across multiple limb joints - also monitors muscle TONE & BALANCE
2) the Projection Level
Made up of the …. … … (precentral gyrus) & ….
2) the Projection Level
Made up of the PRIMARY MOTOR CORTEX (precentral gyrus) & BRAINSTEM
The Projecttion Level
… … … in the primary cortical motor areas & brainstem:
- synapse with … … …., which are motor neurons of the cranial nerves (brainstem) or spinal nerves
Upper motor neurons from cortical motor areas produce the direct (…..) system, eg:
- Corticospinal tracts:
- Regulates … & skilled movement
- Plays some role in modulating …. input - Corticobulbar tracts:
- …. expression, … movements, movements of …..
The Projecttion Level
UPPER MOTOR NEURONS in the primary cortical motor areas & brainstem:
- synapse with LOWER MOTOR NEURONS, which are motor neurons of the cranial nerves (brainstem) or spinal nerves
Upper motor neurons from cortical motor areas produce the direct (PYRAMIDAL) system, eg:
- Corticospinal tracts:
- Regulates FAST & skilled movement
- Plays some role in modulating SENSORY input - Corticobulbar tracts:
- FACIAL expression, TOUNGE movements, movements of MASTICATION
The Projection Level
Upper motor neurons from the brainstem motor areas form the indirect (….., ……) system
- …… tracts
- Head, neck & eye movements
- …. tracts
- Flexor tone, large muscle movements & fine motor control
- ….. tracts
- Maintains skeletal muscle tone and initiates the central pattern generator in the spinal cord
- …. tracts
- Maintains balance & muscle tone
The Projection Level
Upper motor neurons from the brainstem motor areas form the indirect (MULTINEURONAL, EXTRAPYRAMIDAL) system
- TECTOSPINAL tracts
- Head, neck & eye movements
- RUBRROSPINAL tracts
- Flexor tone, large muscle movements & fine motor control
- RETICULOSPINAL tracts
- Maintains skeletal muscle tone and initiates the central pattern generator in the spinal cord
- VESTIBULOSPINAL tracts
- Maintains balance & muscle tone
Corticospinal tract: Direct (Pyramidal) Tract
Origin is from the … …. ….
Corticospinal tract: Direct (Pyramidal) Tract
Origin is from the PRIMARY MOTOR CORTEX
Corticospinal Tract Decussation
…. (… ….) formed by the large pyramidal (corticospinal) tracts descending from the motor cortex
…. …. (…. ….) axons of the pyramidal tracts cross over to the opposite side at the medulla - spinal cord junction
Corticospinal Tract Decussation
PYRAMIDS (OPEN MEDULLA) formed by the large pyramidal (corticospinal) tracts descending from the motor cortex
PYRAMIDAL DECUSSATION (CLOSED MEDULLA) axons of the pyramidal tracts cross over to the opposite side at the medulla - spinal cord junction
Corticospinal Tracts - Summary
… … : “… … …”
- Precentral gyrus of the cerebral cortex
… ….
- Internal capsule, through midbrain (cerebral peduncle) and pons, passing into the pyramidal tract in the medulla
…..
- Most fibres decussate at the medulla-spinal cord junction
… ….
- Lateral corticospinal tracts (crossed & uncrossed), some fibres stay in ipsilateral anterior (ventral) corticospinal tract
…..: “… … …”
- Cell bodies in ventral horn of spinal gray matter
Corticospinal Tracts - Summary
CELL BODIES : “UPPER MOTOR NEURONS”
- Precentral gyrus of the cerebral cortex
BRAIN PATHWAY
- Internal capsule, through midbrain (cerebral peduncle) and pons, passing into the pyramidal tract in the medulla
DECUSSATION
- Most fibres decussate at the medulla-spinal cord junction
SPINAL PATHWAYS
- Lateral corticospinal tracts (crossed & uncrossed), some fibres stay in ipsilateral anterior (ventral) corticospinal tract
ENDPOINT: “LOWER MOTOR NEURONS”
- Cell bodies in ventral horn of spinal gray matter
Corticospinal Tracts - Summary
Most corticospinal neurons synapse on ….
- regulate overall excitability
In … …. of grey matter, some corticospinal neurons synapse … with motor neurons
….. … … …. ….
- 50% - cervical level
- 20% - thoracic level
- 30% lumbosacral level
Brain “commands” are integrated by spinal neural circuits to produce ….. …..
Corticospinal Tracts - Summary
Most corticospinal neurons synapse on INTERNEURONS
- regulate overall excitability
In CERVICAL ENLARGEMENT of grey matter, some corticospinal neurons synapse DIRECTLY with motor neurons
TERMINATION OF THE CORTICOSPINAL TRACT
- 50% - cervical level
- 20% - thoracic level
- 30% lumbosacral level
Brain “commands” are integrated by spinal neural circuits to produce COMPLEX MOVEMENTS
Corticobulbar Tract: Direct (Pyrimidal) Tract
Origin is from the … … …
… - Mainly contralateral
Terminates in ….
Corticobulbar Tract: Direct (Pyrimidal) Tract
Origin is from the PRIMARY MOTOR CORTEX
BILATERAL - Mainly contralateral
Terminates in BRAINSTEM
Corticobulbar Tracts - Summary
Neurons arise from ventral part of … … …
Starts out in company with the corticospinal tract in … ….
Synapse in … … of …. … in the pons (V, VII) and medulla (X, XI & XII)
Provide … expression, … movement & movements of ….
Corticobulbar Tracts - Summary
Neurons arise from ventral part of PRIMARY MOTOR CORTEX
Starts out in company with the corticospinal tract in INTERNAL CAPSULE
Synapse in MOTOR NUCLEI of CRANIAL NERVES in the pons (V, VII) and medulla (X, XI & XII)
Provide FACIAL expression, TONGUE movement & movements of MASTICATION
Clinical Notes - Corticospinal Tract Deficits:
Contralateral Deficit:
- If lesion … pyramidal decussation on right = left upper limb & lower limb muscles affects
Ipsilateral Deficit:
- If lesion … the pyramidal decussation on right = right limbs below the lesion affected
Clinical Notes - Corticospinal Tract Deficits:
Contralateral Deficit:
- If lesion ABOVE pyramidal decussation on right = left upper limb & lower limb muscles affects
Ipsilateral Deficit:
- If lesion BELOW the pyramidal decussation on right = right limbs below the lesion affected
Indirect (Extrapyramidal) System
Upper motor axons arise from several … ….
Four major nuclei/regions are:
- ….. …. located in tectum or roof of midbrain
- … …. in the midbrain
- … …. in pons & medulla
- …. nuclei in medulla
Four major pathways
- ….spinal tracts
- ….spinal tracts
- ….spinal tracts
- ….spinal tracts
Indirect (Extrapyramidal) System
Upper motor axons arise from several BRAINSTEM NUCLEI
Four major nuclei/regions are:
- SUPERIOR COLLICULUS located in tectum or roof of midbrain
- RED NUCLEUS in the midbrain
- RETICULAR FORMATION in pons & medulla
- VESTIBULAR nuclei in medulla
Four major pathways
- TECTOspinal tracts
- RUBROspinal tracts
- RETICULOspinal tracts
- VESTIBULOspinal tracts
Tectospinal Tracts
Axons arise from … ….
Receives projections from axons originating from the … tracts & the … & inferior …. lobes
Descending fibres innervate spinal nerve motor neurons of … …. … and motor neurons of …(…,…) & …. (…) cranial nerves
Mediates contralateral head and neck movements in response to …. stimuli
Specifically …, … & … movement to allow eyes to track a moving object
Tectospinal Tracts
Axons arise from SUPERIOR COLLICULUS
Receives projections from axons originating from the OPTIC tracts & the OCCIPITAL & inferior PARIETAL lobes
Descending fibres innervate spinal nerve motor neurons of CERVICAL SPINAL CORD and motor neurons of MIDBRAIN (III, IV) & PONS (VI) cranial nerves
Mediates contralateral head and neck movements in response to VISUAL stimuli
Specifically HEAD, NECK & EYE movement to allow eyes to track a moving object
Rubrospinal Tracts
Axons arise from … ….
Descending fibres innervate spinal nerve motor neurons of … … …
Mediates … …, large … movements & … …. …. in the opposite upper body
Rubrospinal Tracts
Axons arise from RED NUCLEUS
Descending fibres innervate spinal nerve motor neurons of CERVICAL SPINAL CORD
Mediates FLEXOR TONE, large MUSCLE movements & FINE MOTOR CONTROL in the opposite upper body
Retticulospinal Tracts
Axons arise from …. …. of the … & ….
Maintains …. … … & initiates the … … … in the … ….
Retticulospinal Tracts
Axons arise from RETICULAR FORMATION of the PONS & MEDULLA
Maintains SKELETAL MUSCLE TONE & initiates the CENTRAL PATTERN GENERATOR in the SPINAL CORD
Vestibulospinal Tracts
Axons arise from the … … ….
Maintains … & …. via activation of axial (trunk) and limb extensor muscles
Vestibulospinal Tracts
Axons arise from the LATERAL VESTIBULAR NUCLEUS
Maintains BALANCE & MUSCLE TONEvia activation of axial (trunk) and limb extensor muscles
the projection Level - Summary
The …. tracts
- originate from the primary motor cortex
- Synapse with lower motor neurons either in the brainstem or ventral horn of the spinal cord
- Concerned with voluntary, discrete, skilled movements
The … tracts
- originate from the brainstem
- Synapse with lower motor neurons in the ventral horn of the spinal cord
- Mediates vouluntary movement, muscle tone (posture), balance, and regulates the central pattern generator
the projection Level - Summary
The PYRAMIDAL tracts
- originate from the primary motor cortex
- Synapse with lower motor neurons either in the brainstem or ventral horn of the spinal cord
- Concerned with voluntary, discrete, skilled movements
The EXTRAPYRAMIDAL tracts
- originate from the brainstem
- Synapse with lower motor neurons in the ventral horn of the spinal cord
- Mediates vouluntary movement, muscle tone (posture), balance, and regulates the central pattern generator
The Segmental Level - Spinal Cord
The … level of the motor hierarchy
Consist of the …. circuits of the … …
Activating .. … motor neurons of .a single spinal cord segment stimulates a specific group of muscle fibres
The Segmental Level - Spinal Cord
The LOWEST level of the motor hierarchy
Consist of the SEGMENTAL circuits of the SPINAL CORD
Activating VENTRAL HORN motor neurons of .a single spinal cord segment stimulates a specific group of muscle fibres
Lower Motor Neurons
Receive input from upper motor neurons of the … and ….. pathways described earlier
Lower Motor Neurons
Receive input from upper motor neurons of the PYRAMIDAL and EXTRAPYRAMIDAL pathways described earlier
Action potential —-> Events at NMJ
1) Voltage-sensitive … channels open
2) Influx of …. ions
3) Synaptic vesicles fuse to …. …..
4) release …. into …. ….
5) Diffusion across ..
6) Binds to … receptors on …. ….
8) AP in …. … & contraction of muscle
9) ….. broken down by ….
Action potential —-> Events at NMJ
1) Voltage-sensitive CALCIUM channels open
2) Influx of CALCIUM ions
3) Synaptic vesicles fuse to PRESYNAPTIC MEMBRANE
4) release ACETYLCHOLINE into SYNAPTIC CLEFT
5) Diffusion across CLEFT
6) Binds to NICOTINIC RECEPTORS receptors on POSTSYNAPTIC MEMBRANE
8) AP in MUSCLE CELL & contraction of muscle
9) NEUROTRANSMITTER broken down by ACETYLCHOLINESTERASE
