ILA7 - Stroke/weakness Flashcards
What are the two types of dysphasia?
Receptive and expressive
What is receptive dysphasia?
Lesion in Wernicke’s area, difficulty in understanding language
What is expressive dysphasia?
Lesion in Broca’s area. Trouble with expressing, say words but dont make sense.
In what percentage of right handed people are Brocas and Wernickes areas on the left side?
98%
In what percentage of left handed people are Brocas and Wernickes areas on the right side?
60%
Name some of the key areas in the frontal lobe.
- Central sulcus & Sylvian/lateral sulcus
- Prefrontal cortex (at front, complex cognitive processes)
- Premotor cortex (ant. to primary motor cortex)
- Primary motor cortex (pre-central gyrus, movement)
- Broca’s area (ant. inf. dominant side, speech generation)
- Sup, middle and inf frontal gyri
Name some key areas in the temporal lobe.
- Sup, midlle and inf temporal gyri
- Wernicke’s area (post to Broca’s, below lateral sulcus, speech reception and association)
- Function is to process sensory info to derived meanings for appropriate response, language comprehension and emotional association
Name some key areas in the parietal lobes.
- Bound by central sulcus (ant.) and parieto-occipital sulcus (post), above temporal lobe
- Function is to integrate sensory info from various parts of the body
- Primary somatosensory cortex (postcentral gyrus, sensation)
What are the folds of dura mater that divide the cerebellum?
Tentorum cerebelli (superior) and the falx cerebelli (divides in two)
Which cranial fossa is the cerebellum located?
Posterior
What connects the 2 lobes of the cerebellum?
Vermis
What are the 3 LOBES of the cerebellum?
anterior, posterior and floccunlonodular
What are the hemispheres and zones of the cerebellum?
Vermis, intermediate and lateral hemispheres
What are the functional areas of the cerebellum?
Cerebrocerebellum, spinocerebellum and vestibulocerebellum
What is the function of the vermis?
DOES NOT ALLOW COMMS BETWEEN 2 HEMISPHERES
- posture
- limb movements
- eye movements
Function and position of the cerebrocerbellum.
Lateral parts of the cerebellum. Planning movements and motor learning.
Function and position of the spinocerebellum.
Vermis and more medial parts of 2 hemispheres. Regulating body movements, receives proprioceptive info.
Function and position of vestibulocerebellum.
Flocculonodular lobe. Control balance and ocular reflexes.
What are the parts of the brain stem (sup to inf)?
Midbrain, pons, medulla oblongagta
What are the two areas of the midbrain called and what separates them?
Tectum (post) and tegmentum (ant). Cerebral aqueduct.
There is also the cerebral peduncles, seperated by the substantia nigra
What makes up the tectum?
Superior and inferior colliculi (sup = visual, inf = auditory)
Why is the substantia nigra black/grey? What does it produce?
Neuromelanin. Dopamine
What is the function of the pons?
Act as comms between cerebrum and cerebellum
What is the function of the medulla oblongata
Houses asc and desc tracts. Control of various functions.
What is Cn 1? Is it sensory or motor? What is its function? Where does it leave the skull?
Olfactory. Sensory. Smell from olfactory epithelium. Cribriform plate in ethmoid bone.
What is Cn 2? Is it sensory or motor? What is its function? Where does it leave the skull?
Optic. Sensory. Vision. Optic canal.
What is Cn 3? Is it sensory or motor? What is its function? Where does it leave the skull?
Occulomotor. Motor. Innervates extraocular muscles (LPS, SR,IR,MR,IO), also supplies the sphincter pupillae and the ciliary muscles of the eye (parasympathetic). Superior orbital fissure.
What is Cn 4? Is it sensory or motor? What is its function? Where does it leave the skull?
Trochlear. Motor. Superior oblique (tendon does through the trochlea). Superior orbital fissure.
What is Cn 5? Is it sensory or motor? What is its function? Where does it leave the skull?
Trigeminal. I-opthalmic (sensory), scalp to nose, superior orbital fissure
II-maxillary (sensory), nose to top lip, foramen rotundum
III-mandibular (both), sensory is ant 2/3 of tongue, skin and lower teeth, motor is muscles of mastication, foramen ovale
What is Cn 6? Is it sensory or motor? What is its function? Where does it leave the skull?
Abducens. Motor. Lateral rectus. Superior orbital fissure
What is Cn 7? Is it sensory or motor? What is its function? Where does it leave the skull?
Facial. Both. Sensory= outer ear, taste from ant 2/3 of tongue. Motor= facial expression, mucous membrane. Internal acoustic meatus then stylomastoid foramen.
What is Cn 8? Is it sensory or motor? What is its function? Where does it leave the skull?
Vestibulocochlear. Sensory. Hearing, balance. Internal acoustic meatus.
What is Cn 9? Is it sensory or motor? What is its function? Where does it leave the skull?
Glossopharyngeal. Both. Sensory= general and special from post 1/3of tongue, ear. Motor= parotid and stylopharyngeus. Jugular foramen.
What is Cn 10? Is it sensory or motor? What is its function? Where does it leave the skull?
Vagus. Both. Sensory= ear, larynx, pharynx, taste from epiglottic part of tongue. Motor= most muscles of pharynx and larynx. Jugular foramen.
What is Cn 11? Is it sensory or motor? What is its function? Where does it leave the skull?
Spinal accessory. Motor. Trapezius, sternocleidomastoid and some fibres run with Cn 10 to viscera. Jugular foramen.
What is Cn 12? Is it sensory or motor? What is its function? Where does it leave the skull?
Hypoglossal. Motor. Tongue muscles except palatoglossus (Cn10). Hypoglossal canal.
What is the sulcus that separates the two pyramids?
Anterior median sulcus
What is the sulcus that separates the pyramids from the olives?
Ventero-lateral sulcus
What is the sulcus that lies outside the olives?
Postero-lateral sulcus
Which tracts run through the pyramids (anterior surface of medulla)?
Corticospinal and corticobulbar (and so are the pyramidal tracts)
Which tracts run through the olives (ant. surface of medulla)?
Tectospinal, rubrospinal, vestibulospinal and reticulospinal (extrapyramidal tracts)
Where does sensory information come from in the cuneate fasciculi?
Cuneate means wedge shaped, and so senory information from upper body
Where does sensory information come from in the gracile fasciculi?
Lower body, Walking gracefully
What are the 2 groups of descending pathways?
Pyrimadal and extra pyramidal
Where do pyramidal tracts originate?
Cerebral cortex
Which parts of the body are in the medial aspect of the homunculus?
Leg, feet and genitals.
What do the pyramidal tracts control.
Voluntary control of muscles
What are the 2 pyramidal tracts?
Corticospinal and bulbospinal
What is the general route descending pathways take?
Fibres start seperate, go through the corona radiata. They then join and go though the internal capsule. Then on to the brainstem and spinal cord
Describe the corticospinal tract.
- Goes to the musculature of the body
- Input from primary motor, pre motor and somatosensory centres
- Pass through crus cerebri of midbrain, pons and into medulla within the peduncles (motor only)
- Divide into lateral corticospinal (90% of fibres, cross over at base of pyramids in medulla) and anterior corticospinal (10% of fibres, desc down the spinal cord then cross )
Describe the corticobulbar tract.
- Musculature of the head and neck
- Same input and origin as corticospinal
- Terminate on brainstem on motor nuclei of cranial nerves
- Lower motor neurons carry signals to the head and neck
Where do the extrapyramidal tracts originate?
Brainstem
What do the extrapyramidal tracts control?
Voluntary and involuntary control of all musculature such as muscle tone, balance, posture and locomotion
Where do the extrapyramidal tracts synapse?
No synapses within the descending pathways. All synapse with the lower motor neurons. Cell bodies all in cerebral cortex or brainstem and axons remain in CNS
What are the 4 extrapyramidal tract?
Tectospinal, rurbrospinal, vestibulospinal, reticulospinal
Describe the tectospinal tract.
- Responsible for head turning in response to visual stimuli
- superior colliculus, head and eye movements
Describe the rubrospinal tract.
- Assist in motor functions, not really used in humans other animals more so (why cats land on feet when thrown out a window)
- Less developed corticospinal
- Red nucleus (rubro, red)
Describe the vestibulospinal tract.
- Musle tone and posture
- Vestibular nuclei, balance and posture
Describe the reticulospinal tract.
- Spinal reflexes
- Reticular formation (midbrain), posture and locomotion
What areas are supplied by the anterior cerebral artery?
- Most of the midline portions of the frontal lobes (medial surface and upper portions) and the superior medial parietal lobes
- 4/5ths of the corpus callosum
- Deep structures such as anterior limb of the internal capsule
- Anteromedial portion of the cerebrum
What areas are supplied by the middle cerebral artery?
-Majority of the lateral surface of the hemisphere (except the superior inch of the frontal and parietal lobe (ACA) and the deep structures of the anterior hemisphere
What areas are supplied by the posterior cerebral artery?
- Supplies the occipital lobe and the posterior temporal lobe
- Supplies the medial surfaces of the thalamus and walls of the IIIrd ventricle via the thalamoperforating branches
- Supplies the thalamus via the peduncular perforating branches
- Supplies the choroid plexus
Which arteries supply the cerbellum?
Superior cerebellar, anterior inferior cerebellar and posterior inferior cerebellar
What is the difference between upper and lower motor neuron?
Upper runs from motor cortex then synapses (glutamate)onto lower in the anterior horn of the grey matter in spinal cord or in the brain stem. Whereas a lower mn goes from the synapse to the muscle, where it synapses (ACh).
Describe upper motor neurons.
- cell bodies in cerebral cortex
- Axons in CNS
- Controls movement, tone, spinal reflexes, autonomic functions, sensory info to higher centres
Describe lower motor neurons.
a) Motor neurons of the cord and brain stem
- Those from brainstem carry motor signals to the muscles of the face and neck (Corticobulbar tracts)
- In spinal cord: Synapse with upper motor neurons at the ventral horn and then go on to supply the muscles of the bdoy
b) Motor neurons located in either:
- The anterior grey column
- Anterior nerve roots
- Cranial nerve nuclei of the brainstem and cranial nerves with motor function
c) Function
- Control of all voluntary movement (innervate the skeletal muscle fibres)
- Act as a link between upper motor neurons and muscles
- Directly innervate the muscles to produce movement
Describe the pattern of weakness in an upper motor neuron lesion.
- Board weakness
- Increased muscle tone (specificity) as uncontrolled LMN activation (most UMN are inhibitory)
- High then low resistance to movement (clasp knife)
- Increased deep tendon reflexes
- Decreased superficial tendon reflexes
- Flexors weaker than extensors in legs
- Extensors stronger than fkexors in arms
- Babinski sign, big toe raised (usually curled) when bottom of foot is stimulated
- Minimal atrophy
Describe the pattern of weakness in a lower motor neurone.
- Decreased tone
- Paralysis
- Weakening and wastage (atrophy)
- Absence of relevant reflexes (arreflexia)
- Muscle fasciculations
What is the difference between weakness and fatigue?
Weakness is constant loss of strength, whereas fatigue is the gradual onset and build up a lack of strength
What are the key parts of a neurological history for a patient with weakness?
a) Pattern of weakness
- Proximal or distal (prox=polyneuropathy, dis=myopathic)
- Location and symmetry of weakness (single limb= spinal nerve root compression,general= CNS damage or pathology attacking neurons, limb and face same side= above brainstem)
b) Associated symptoms
- twitching or atrophy
- vertigo, vision disturbance = wider spread
- myelopathy
c) Temporal characteristics
- Chronic or episodic
- Tempo of onset and progression
d) Family hist of hereditary neuropathies
e) Pain
Describe the weakness in MND.
-Fluctuating strength
Describe the weakness in myopathies.
- Proximal and symmetrical
- Usually minimal atrophy until later except myotonic dystrophy
Name some causes of upper motor neuron weakness.
Stoke, lesion, tumour, SC compression, acute transverse myelitis, spinal cord infarct, spinal epidural or subdural haemorrhage, intervertebral disc herniation and MS
Name some causes of LMN weakness.
Guillian-Barre, heavy metal poisioning, Bell’s Palsy, alcohol/drug induced, diabetic and plexopathies (brachial, lumbar)
Name some neuromuscular causes of weakness.
Myasthenia gravis (autoimmune), tick paralysis, Lambert-Eaton myasthenic syndrome and organophosphate poisoning
Name some muscular causes of weakness.
Inflammatory, alcohol/drug induced, muscular dystophy, endocrine related
Is motor facial nerve innervation to forehead bilateral or unilateral?
Bilateral
Is motor facial nerve innervation to lower face bilateral or unilateral?
Unilateral, contralateral
Where would a lesion occur in the facial nerve to cause forehead sparing weakness?
Central (brain), eg stroke
Where would a lesion occur in the facial nerve to cause whole facial weakness?
In the facial nerve (peripheral)
