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97 Cards in this Set

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Describe conscious proprioception?
Information about limb position sense carried in the dorsal column - medial lemniscus system is considered "conscious" proprioception because it reaches the cerebral cortex.
Describe unconscious proprioception
1) Ia, Ib, & II fibres send afferents to Clarke's nucleus where they synapse
2) Those axons then travel to the cerebellum via the dorsal spinocerebellar tract (C8 to L3)
3) Fibres below L3 travel in the F. gracilis) to L3 where they synapse in Clarke's nucleus.
4) Fibres above C8 travel with F. cuneatus, synapse in accessory cuneate nucleus (equivalent to Clarke's), fibres then travel in cuneocerebellar tract to cerebellum.
Describe the path of the Spinothalamic Tract
1) Arises from Lamniae I, IV- VI
2) Crosses midline in the AWC
3) Projects to VPL
4) Projects to primary somatosensory
Note - pain, temp and light touch sensations mainly carried by A-delta fibres.
Describe myasthenia gravis
Myasthenia gravis is characterized by moderate to profound weakness of skeletal muscles, is caused by circulating antibodies that react with post-synaptic nicotinic acetylcholine receptors
What does injury to one side of the corticospinal cord cause?
1) Weakness (hemiparesis) or paralysis (hemiplegia) of the ipsilateral upper and lower extremities
What does bilateral cervical spinal cord damage result in?
bilateral cervical spinal cord amage above C4 - C5 may result in paralysis of all four extremities (quadriplegia)
Describe the paleospinothalamic and spinoreticulothalamic tracts
Paleospinothalamic and spinoreticulothalamic tracts:
1) These two tracts are thought to have a role in the sensation of dull aching, poorly localized pain related to that mediated by C fibers.
2) Also have a role in affect and cortical arousal association with pain.
3) These are subsets of spinothalamic fibers which project to the medial nuclei of the thalamus (DM and intralaminar)
4) They then project to the association areas if the cortex.
Name three modulators of the pain process
1) At the spinal cord level
2) The spinomesencephalic tract
3) Central modulation
Explain how the spinal cord modulates pain processing.
1) Modulation is done by the interneurons in SG (Laminae II) of the dorsal horn which receive descending inhibition signals.These act on incoming pain and temp information and modulate both fast and slow pain.
2) Efferents from the PAG to reticular formation of nuclei in the rostral medulla / caudal pons. These send descending information to the dorsal horn (SG) of the spinal cord.
3) Large diameter afferents which conduct touch can also modulate pain through connections with the SG and dorsal horn laminae.
Explain how the spinomesencephalic tract modulates pain processing.
1) A subset of fibers synapses in the midbrain reticular formation and PAG
2) The PAG region has reciprocal connections with the limbic system through the hypothalamus
3) PAG also sends a descending projection to the dorsal horn (substantia gelatinosa (SG), Lamina II)
4) It also receives input from the cortex, hypothalamus and limbic structures
What aspects of central modulation affect pain processing?
1) Opiate receptors and endogenous opiate peptides are found diffusely throughout the brain.
2) These are in highest concentration in the PAG, rostral ventral medulla, spinal cord dorsal horn and areas of the hypothalamus that project to the PAG.
What system carries pain from the head?
pain from the head is carried by the trigeminal system.
- The spinal tract and nucleus of V correspond to the SThT and mediate fast pain
- The indirect pathways of the spinal cord (reticular formation, medial thalamus and widespread areas of the cerebral cortex) carry the information for slow pain.
Describe the components from the trigeminal (V) nucleus and nerve
1. Sensory Components (from Head)
a) Main (chief) sensory - touch & pressure
b) Spinal nucleus and tract V - pain & temp from head
c) Mesencephalic nucleus - proprioceptive
2. Motor nucleus of V (motor to muscles of mastication)
Describe the components of the facial (VII) nucleus and nerve
1) SSA - taste from anterior 2/3 of tongue
2) Main motor nucleus - Facial expression
3) Secreto-motor nucleus (visceral motor) - to submandibular and sublingual salivary glands and lacrimal gland.
Name the blood supply to the caudal medulla
1) Anterior spinal artery (ASA)
2) Vertebral Artery (VA)
3) Posterior spinal artery (PSA)
Name the blood supply to the Rostral Medulla
1) Anterior spinal artery (ASA)
2) Vertebral Artery (VA)
3) Posterior inferior cerebelllar artery (PICA)
Name the blood supply to the Pons
1) Basilar artery (Primary)
2) Anterior inferior cerebellar artery (AICA)
3) Superior cerebellar artery (SCA)
Name the blood supply to the midbrain
1) Posterior cerebral artery
Name the principles that allow for cerebellar lesions to be localized
1. Ataxia is ipsilateral to the side of a cerebellar lesion
2. Midline lesions of the cerebellar vermis mainly cause unsteady gait and eye movement accompanied by vertigo, nausea and vomiting.
3. lesions lateral to the cerebellar vermis mainly cause ataxia of the limbs (appendicular ataxia)
name the four functional groups of the cerebellum
1. Lateral hemispheres
2. Intermediate hemispheres
3. Vermis
4. flocculonodular lobe.
What is the function of the lateral hemisphere of the cerebellum?
Motor planning for extremities
What is the function of the intermediate hemisphere of the cerebellum?
Distal limb coordination
What is the function of the vermis?
Vermis = Proximal limb and trunk coordination
Blood supply to the cerebellum is supplied by which three arteries?
1. The posterior inferior cerebellar artery (PICA)
2. The anterior inferior cerebellar artery (AICA)
3. The superior cerebellar artery (SCA)
Name the main components of the basal ganglia
Caudate,
lentiform nucleus (Putamen, Globus-pallidus),
Subthalamic nucleus,
Substantia nigra,
What is "hemiballismus"?
An unilateral wild flinging movements of the extremities contralateral to a lesion in the basal ganglia, typically involving the subthalamic nucleus
Name the four parallel channels through the basal ganglia
1. Motor channel (putamen)
2. Oculomotor (caudate, body)
3. Prefrontal (Caudate, head)
4. Limbic (Nucleus accumbens; central caudate, ventral putamen)
Define: bradykinesia
"slowed movements"
Define: Hypokinesia
"decreased amount of movements"
Define: Akinesia
"Absence of movements"
What are components of the pyramidal system?
1. Motor cortex
2. Pyramidal tract
3. Anterior horn cells
What are components of the extra-pyramidal system?
1. Basal ganglia
2. Thalamus
Describe the characteristic pathology of the pyramidal system
1. Spasticity - velocity dependent resistance to movement; more obvious with quick movements
2. Weakness
3. Paralysis
Describe the characteristic pathology of the extra-pyramidal system
1. Rigidity - not velocity dependent; constant resistance
2. NO Weakness but clumsiness and involuntary movements
3. NO Paralysis; increased or decreased movements
Name the three cerebellar peduncles
1. Inferior cerebellar
2. middle cerebellar
3. Superior cerebellar
What is the Flocculonodular lobe of the cerebellum responsible for?
Flocculonodular lobe = balance and vestibulo-ocular reflexes
What areas of the brain does the anterior cerebral artery supply?
The ACA supplies the medial surface if the hemisphere from the frontal pole to the parieto-occipital sulcus
Where is the most common site of aneurysms?
The anterior communicating artery (which connects the two anterior cerebral hemispheres is the most common site of aneurysms of the circle of Willis.
What portions of the motor / sensory cortices does the ACA irrigate?
The leg-foot areas
What areas of the brain does the middle cerebral artery supply?
The MCA supplies the lateral convexity of the hemisphere which includes:
1. Broca's and Wernicke's areas
2. The face and arm areas of the motor and sensory cortices
3. The frontal eye field
Name the components of the basal ganaglia
Components of the Basal Ganglia:
1. Caudate nucleus
2. Putamen
3. Globus Pallidus
Groupings of the basal ganglia: define the striatum
striatum = caudate nucleus + putamen+globus pallidus
Groupings of the basal ganglia: define the lentiform nucleus
the lentiform nucleus = Globus pallidus + putamen
What are the basal ganglia involved in?
The basal ganglia are involved in the modulation of voluntary motor activity
What is the blood supply for the globus pallidus (lateral and medial segments)?
The middle cerebral artery (MCA)
What is the blood supply of the subthalamic nucleus?
The posterior cerebral artery and posterior communicating arteries
What is the blood supply of the caudate, putament and internal capsule?
Branches of the MCA (medial and lateral striae)
Name the three functions of the cerebellum
1. Maintenance of posture and balance
2. Maintenance of muscle tone
3. Coordination of voluntary motor activity
Describe anterior vermis syndrome
Usually involves leg region
Results from atrophy of rostral vermis - most commonly by alcohol abuse
Causes gait, trunk and leg dystaxia
Describe posterior vermis syndrome
Usually involves the flocconodular lobe
Results from brain tumors
Causes trunkal ataxia
Describe hemispheric syndrome
Usually involves one cerebellar hemisphere
Result of brain tumor or abscess
Causes arm, leg and gait ataxia and IPSILATERAL cerebellar signs
What do the inferior peduncles carry?
1. Afferent fibres from:
A. spinal cord (Spinocerebellar, Cuneocerebellar tracts)
B. inferior olive
C. the vestibular nuclei
2. Efferent fibres from
A. Vestibulocerebellar tract
B. Olivocerebellar tract
C. Post-spinocerebellar
What fibres do the middle cerebellar peduncles carry?
Carry pontocerebellar fibres that originate in contralateral pontine nuclei and terminate in cerebellum
What fibres do the superior peduncles carry?
1. Afferent fibres from
A. Anterior spinocerebellar tract
B. Acoustic & optic information
2. Efferent fibres from
A. Red nucleus
B. Thalamus
What cerebellar structures does PICA supply?
Most of the inferior surface of cerebellar
1. hemispheres
2. Vermis
3. Rostal medulla
What cerebellar structures does PICA supply?
More lateral portions of the inferior surface of the cerebellum, including; flocculus, caudal parts of inferior and middle cerebrllar peduncles
What structures are supplied by the SCA?
They supply the superior surface of the cerebellum, most cerebellar nuclei, rostral parts of the middle cerebellar peduncle and all of the superior peduncle.
What three arteries supply the cerebellum?
1. PICA
2. AICA
3. SCA
What to the vestibulocerebellar afferents provide information from?
- provide information about the position of the head and body in space
- help to orient eye movements during locomotion
What occurs when there is a lesion of the vestibulocerebellum?
- Disturbances in vestibular function / balance and eye movements
A) limb ataxia - incoordination
B) Staggering wide based gait
C) May sway when walking
D) Truncal ataxia
E) Nystagmus
Spinocerebellar connections carry what kind of information?
Carry proprioceptive information from spinal cord to cerebellum. Called unconscious proprioception
What characterizes a lesion of the spinocerebellum?
Anterior lobe syndrome (Spinocerebellar disturbance)
results in postural instability:
A) Limb ataxia
B) Staggering wide based gait
What are the afferents of the spinocerebellar connections?
Dorsal
- Ia, II fibres from muscle spindles
- Proprioception
- Fibers from clarke's column
(travel through ICP)
Anterior
- IIb fibres from golgi tendon organ
- Muscle force
(travel through SCP)
What do the corticopontine connections do?
Influence planning, initiation, timing and coordination of voluntary movement
What are the vestibulospinal tracts important for?
Are important mediators of postural adjustments and head movements.
1. lateral = facilitates extensors
2. Medial = influences neck and axial muscles
What role do the reticulospinal tracts play?
Play a role in influencing voluntray movement and muscle tone
Rubrospinal tract plays what function?
Has a minor role in influencing voluntary movement
(facilitates flexor and extensor muscle activity)
Probably of minor importance in humans
Describe the mamillary body of the hypothalamus?
- receives input from hippocampal formation via fornix
- projects to anterior nucleus of thalamus
Where are the hemorrhagic lesions caused by Wernicke's encephalopathy located?
They are located in the mamillary body of the hypothalamus
Describe the Fornix of the Hypothalamus
- Major fibre system of the hypothalamus
- Largest projection to the hypothalamus
- It projects
Hippocampal to mammillary nucleus, anterior nucleus of thalamus and septal area
Describe the mamillothalamic tract of the hypothalamus
- Major fibre system of the hypothalamus
- Projects from the mamillary nuclei to tha naterior nucleus of the thalamus
- Part of papez circuit
What are the four main functions of the hypothalamus?
1. Autonomic function (anterior / posterior hypothalamus)
2. Temperature regulation
3. Water balance
4. Food intake regulation
In general terms what role does the limbic system play?
The limbic system is considered the anatomic substrate that underlies behavioral and emotional expression
It is expressed through the hypothalamus by way of the autonomic NS
Describe the olfactory nerves (CN I)
- bipolar neurons
- Dendrites extend to surface - specialized as receptors
- Axons collected into bundles that form the olfactory nerve. These cross the cribiform plate and synapse in olfactory bulb where processing occurs
- Olfactory tract carries information to primary olfactory cortex
Describe the components of the olfactory nerve (CN I)
1. SSA: mediates smell
Describe the components of the optic nerve (CN II)
1. SSA: Vision and light relfexes
Describe the components of the occulomotor nerve (CN III)
1. GSE:
Eye muscles: medial, superior, inferior rectus muscles as well as the inferior oblique.
Upper eyelid: levator palpebrae muscle
2. GVE: sphincter muscle of iris (miosis) and ciliary muscle (accomodation)
Describe the components of the trochlear nerve (CN IV)
1. GSE: innervates superior oblique muscle (depresses and abducts eye)
remember: LR6, SO4 all others 3
Describe the components of the Trigeminal nerve (CN V)
1. SVE: special visceral
- muscles of mastication
2. GSA General somatic afferent
- sensory innervation of face
Describe the components of the abducent nerve (CN VI)
1. GSE: innervates the lateral rectus muscle of the eye (abducts the eye)
Remember LR6, SO4, All others 3
Describe the components of the facial nerve (CN VII)
1. GSA: posterior surface of external ear
2. GVA: minor role (not clinically important)
3. SVA: taste buds from anterior 2/3 of tongue
4. GVE: lacrimal, submandibular and sublingual glands
5. SVE: stapedius muscle of middle ear, muscles of facial expression
Describe the components of the vestibulocochlear nerve (CN VIII)
1. SSA: equilibrium and balance, hearing
Describe the components of the glossopharyngeal nerve (CN IX)
1. GSA: external ear
2. GVA: Carotid sinus
3. SVA: tase from posterior 1/3 of tongue
4. SVE: stylopharyngeus muscle
5. GVE: parotid gland
Describe the components of the accessory nerve (CN XI)
1. SVE: mediates head and shoulder movement, and innervates laryngeal muscles
Describe the components of the hypoglossal nerve (CN XII)
1. GSE: mediates tongue movements
How many spinal nerves are there?
31 in total:
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
What does the posterior horn of the spinal cord do?
Receives and processes sensory information
What does the anterior horn of the spinal cord do?
The cell bodies of nerves inverating skeletal muscles are found here
Define: Clarke's Nucleus
Clarke's nucleus is a small section of grey matter located in lamina VII of the intermediate zone spinal cord which is found ventral to the gracile column and cuneate column and is involved in unconscious proprioception. It is found at the level of T1-L2 (lumbar vertebrae) on the spinal cord.
What makes up the posterior arterial supply of the CNS?
1. Vertebral arteries (give rise to: Anterior / posterior spinal arteries, PICA)
2. Basilar artery (Give rise to AICA, Pontine arteries, SCA)
3. POsterior cerebral arteries
What makes up the anterior arterial supply of the CNS?
1. The internal carotids (give rise to ACA, MCA)
Spinal cord vasculature: describe the anterior spinal artery
- branches off each vertebral artery to join and form ASA
- Runs in anterior median fissure
- Supplies 2/3 of paramedian and lateral areas
Spinal cord vasculature: describe the posterior spinal arteries
- Arise from veretbral arteries or PICAs
- Run in posterolateral sulci
- Supply posterior 1/3 of cord (dorsomedial and dorsolateral areas)
What is the function of the dorsal column - medial lemniscus pathway
mediates tactile discrimination, vibration sensation, form recognition and joint / muscle sensation)
What receptors feed the dorsal column - medial lemniscus pathway
Pacini's
Meissner's tactile corpuscle
joint capsules
muscle spindles
Golgi tendon organs
What is the function of the lateral spinothalamic tract?
mediates pain and temperature sensation
What receptors feed the lateral spinothalamic tract?
Free nerve endings
- the lateral spinothalamic tract recieves input from the fast and slow conducting pain fibres (A-delta and C)