anat/physio/patho Flashcards
Name the 4 lobes of the brain
Frontal, parietal, temporal, occipital
List the subdivisions of the frontal lobe and their functions
- Primary motor cortex - execution of movements
- Secondary motor cortex - planning of complex movements
- Broca’s speech area - speech production
- Prefrontal cortex - higher order mental capabilities like behaviour and planning
- Frontal eye field - coordination of eyes to focus on a single object
What is the function of the parietal lobe?
Primary somatosensory cortex where all the information from the somatic sensory pathways are transmitted to and processed
Describe what is the sensory homunculus
A visual representation of how much processing power is allocated through all the body parts.
Face and hands are the most, ie. they can do the most precise fine motor functions and are the most sensitive.
What is the function of the temporal lobe?
- Primary auditory cortex = process hearing information coming from CN8
- *Wernicke’s speech area = speech understanding
What are the 2 areas of the brain responsible for speech and which lobes are they found in respectively?
Broca’s = speech PRODUCTION, found in frontal lobe
Wernicke’s = speech INTERPRETATION, found in temporal lobe
What is the function of the occipital lobe?
Primary and secondary visual cortex = VISION
What 2 functions does the cerebellum play an important role in?
Balance and coordination
List the anatomical divisions of the cerebellum
From medial to lateral,
1. Vermis **
2. Intermediate zone
3. Lateral hemispheres
List the functional divisions of the cerebellum
- Vestibule cerebellum - postural maintenance
- Spinocerebellum - Integrate sensory input with motor commands
- Cerebrocerebellum
Which part of the brainstem is the cardiopulmonary centre?
Medulla oblongata
Which part of the brainstem does the cranial nerves 5,6,7,8 branch from?
Pons
Which cranial nerves emerge from the pontomedullary junction?
Cranial nerves 5,6,7,8
Name the 4 branches of the ICA
- Ophthalmic artery
- Anterior cerebral artery
- Middle cerebral artery
- Posterior communicating artery
Where does the ophthalmic artery supply?
Orbit
Forehead via supratrochlear artery
Dorsum of nose via supraorbital artery
Which part of the brain does the ACA supply?
- Midline of frontal lobe
- Superior medial parietal lobe
Which part of the brain does the MCA supply?
- Lateral cerebral cortex
- Anterior temporal lobes
Which artery does the posterior communicating artery connect to?
Posterior cerebral artery
Describe which is the main artery supplying the intra and extra cranial structures
Intra-cranial: ICA and vertebral arteries
Extra-cranial: ECA
Which part of the brain does the PCA supply?
- Occipital lobe
- Temporal lobe
- Thalamus
- Choroid plexus of third and lateral ventricles
Which special sense will be affected if the PCA is occluded?
Vision
Because the PCA supplies the occipital lobe which houses the primary visual cortex
List the significance of the Circle of Willis
- Provides collateral blood flow between the anterior and posterior circulations of the brain to PROTECT AGAINST ISCHEMIA
- Common site for berry/saccular aneurysms which is the most common cause of non-traumatic SAH.
What is the main vessel supplying the extra-cranial structures?
External carotid artery
**List the branches of the ECA
- Superior thyroid artery
- Ascending pharyngeal artery
- Lingual artery
- Facial artery
- Occipital artery
- Posterior auricular artery
- Maxillary artery
- Superficial temporal artery
Which nerve is closely related to the superior thyroid artery?
External laryngeal nerve
Which nerve is closely related to the inferior thyroid artery?
Recurrent laryngeal nerve
How does the lingual artery enter the oral cavity?
From behind the hypoglosus muscle
What parts of the face does the facial artery supply?
Muscles of soft palate, sublingual and submandibular gland
Orbicularis oculi and oris
Superficial face
What muscles does the occipital artery supply?
THINK BACK OF NECK!
SCM & trapezius
What is the name of the artery that branches out from ECA within the parotid gland?
Posterior auricular artery
Name the 2 terminal branches of the ECA
Maxillary artery
Superficial temporal arteries
What is a key branch of the maxillary artery involved in SAH?
Middle meningeal artery
How does the middle meningeal artery enter the cranial cavity?
Via foramen spinosum
What is the main artery supplying the EAR?
Posterior auricular artery
What is the artery supplying the muscles of mastication?
Maxillary artery
What is a branch of the maxillary artery that goes to the mandible?
Inferior alveolar artery (passes through mandibular foramen)
Which part of the brain produces CSF?
Choroid plexus
List the functions of CSF
- **Protection for the brain (shock absorption)
- Buoyancy (allows the brain to maintain its density)
- Prevention of brain ischemia (decreasing the amt of CSF in limited space inside the skull decreases total ICP)
- **Removal by-products of metabolism
** Describe CSF circulation in the brain
Produced by choroid plexus
Lateral ventricles to 3rd ventricle via interventricular foramen
3rd to 4th ventricle via cerebral aqueduct
4th ventricles has openings for the CSF to flow into the subarachnoid space
Reabsorbed into dural venous sinuses through arachnoid granulations.
Choroid plexus -> lateral ventricle -> 3rd -> 4th ventricle via aqueduct -> subarachnoid -> arachnoid granulation -> DVS
What structure of the brain reabsorbs/recycles CSF?
Arachnoid granulations
Which is the most clinically important dural venous sinus and what structures pass through it?
Cavernous sinus
CN 3,4,6,V1,V2
Where is the highest number of arachnoid granulations found?
Superior sagittal and tranverse sinuses
Where does dural venous sinuses drain into?
Internal jugular vein
Describe the most common cause of epidural/extradural haemorrhage
Trauma associated with skull fracture, specifically fracture at the pterion
The fracture causes rupture of the MIDDLE MENINGEAL ARTERY
What will I see on a CT scan if there is epidural haemorrhage?
Biconvex (lens-shaped) hyperdense area
Describe the most common cause of subdural haemorrhage
Rupture of bridging veins, especially in elderly due to age related shrinking of the brain causing the distance between the brain and skull to increase.
What will I see on a CT scan if there is subdural haemorrhage?
Crescent-shaped haematoma
Describe the most common cause of subarachnoid haemorrhage
Rupture of berry aneurysm, most commonly at the Circle of Willis.
Or arteriovenous malformation
Or coagulopathies
What will I see on a CT scan if there is subarachnoid haemorrhage?
Blood fills the sulci and around the Circle of willis.
Blood may also pool in the basal cisterns, forming a “star-shaped” pattern.
Describe the most common cause of intraparenchymal haemorrhage
HYPERTENSION!!!
Cerebral amyloid angiopathy
Vascular abnormalities (eg. arteriovenous malformations)
Describe the sequence of events from the photoreceptor to the brain when processing images
- Photoreceptors recieve light and undergo phototransduction.
- Optic nerve exits orbit via optic canal
- Hemi decussation of nasal hemiretina tract at optic chiasm
- Optic tract (ipsilateral temporal and contralateral nasal)
- Synapses at the lateral geniculate nucleus (LGN) of the thalamus
- Optic radiation
- Primary visual cortex in occipital lobe
Which are the 4 nerves with parasympathetic component?
CN 3,7,9,10
What is the parasympathetic function of CN3?
Innervation of the smooth muscles of the eye (ie. sphincter pupillae and ciliary muscles).
Sphincter pupillae is for pupillary light reflex and ciliary muscle is to adjust the lens for accomodation.
What is the parasympathetic function of CN7?
Supply all the glands in the head EXCEPT parotid so lacrimal, sublingual, submandibular
What is the parasympathetic function of CN9?
Innervate the parotid gland and increase its secretions
What is the parasympathetic function of CN10?
Heart, lungs, GIT parasympathetic functions
What is the visual field defect associated with lesion to the optic nerve?
Ipsilateral monocular blindness
What is the visual field defect associated with lesion to the central optic chiasm?
Bitemporal hemianopia
Central optic chiams aka the point of decussation -> both the nasal visual fields affected -> lost of peripheral vision on both sides
In what condition is a lesion to the central optic chiasm seen more often?
Pituitary tumour
What is the visual field defect associated with lesion to the lateral optic chiasm?
Ipsilateral nasal hemianopia
Depending on which side is affected, it affects the ipsilateral temporal vision -> loss of central vision.
Right lateral optic chiasm -> right temporal visual field disrupted -> right central vision gone
What is the visual field defect associated with lesion to the optic tract?
Contralateral homonymous hemianopia.
Right: right temporal (right central) and left nasal (left periphery)
- Right central and Left peripheral vision loss
Left: left temporal (left central) and right nasal (right periphery)
- Left central and Right peripheral vision loss
What is the visual field defect associated with lesion to the optic radiation?
Contralateral quadrantanopia
What is the visual field defect associated with lesion to the Meyer’s loop?
Contralateral quadrantanopia
What is the visual field defect associated with lesion to the visual cortex?
Contralateral homonymous hemianopia with macular sparing
Because even if there is an occlusion -> stroke -> infarct of visual cortex, the visual cortex will still have blood supply from collateral vessels, it will not totally die off.
Hence not complete blindness and got macular sparring.
Where does CN 1 emerge from in the skull? State the cranial fossa component as well
Cribriform plate, anterior CF
Where does CN 2 emerge from in the skull? State the cranial fossa component as well
Optic canal, middle CF
Along with ophthalmic artery which is a branch of ICA
Where does CN 3 emerge from in the skull? State the cranial fossa component as well
Midbrain
Middle CF, supra-orbital fossa
Where does CN 4 emerge from in the skull? State the cranial fossa component as well
Midbrain
Middle CF, supra-orbital fossa
Where does CN 5 emerge from in the skull? State the cranial fossa component as well
Pons
Middle CF
V1: supraorbital fissure
V2: foramen rotundum
V3: foramen ovale
Where does CN 6 emerge from in the skull? State the cranial fossa component as well
Pontomedullary junction
Middle CF; Suspended in cranial cavity
Where does CN 7 emerge from in the skull? State the cranial fossa component as well
Pontomedullary junction
Posterior CF; Internal acoustic meatus
Where does CN 8 emerge from in the skull? State the cranial fossa component as well
Pontomedullary junction
Posterior CF; Internal acoustic meatus; petrous part of temporal bone
Where does CN 9,10,11 emerge from in the skull? State the cranial fossa component as well
Medulla oblongata
Posterior CF; Jugular foramen
Where does CN11 go after emerging from jugular foramen?
Spinal accessory nerve goes through the foramen magnum
Where does CN 12 emerge from in the skull? State the cranial fossa component as well
Medulla oblongata
Posterior CF; Hypoglossal canal
What is the main somatic sensory nerve of the face? And via what tract does it transmit sensory information?
CN V - Trigeminal nerve
Trigeminothalamic tract
What cranial nerves are involved in the pupillary reflex?
CN 2 & 3
What cranial nerves are involved in the accommodation reflex?
CN 2,3,4,6
Name the 2 intrinsic muscles innervated by the parasympathetic component of CN 3
Sphincter pupillae
Ciliary muscles
Where in the cranial cavity does CN7 exit via?
Stylomastoid foramen
Where does the facial nerve branch into its 6 terminal branches?
Within the parotid gland
List the 6 terminal branches of the facial nerve
- Temporal
- Zygomatic
- Buccal
- Marginal
- Mandibular
- Cervical
Which is the only branch of the trigeminal nerve to have a motor component?
V3 - mandibular nerve
Which nerve gives rise to the sensation in the anterior 2/3 of the tongue?
V3 mandibular nerve
Which nerve gives rise to the sensation in the posterior 1/3 of the tongue?
CN 9 glossopharyngeal nerve
Which group of muscles in the face does the motor component of the trigeminal nerve innervate?
Muscles of mastication (eg. medial and lateral pterygoid, masseter and temporalis)
What will I observe in a patient with CN 4 palsy?
In front gaze, the affected eye will be elevated and slightly adducted.
This is because of denervation to the superior oblique muscle that depress, adducts and internally rotates the eye.
What muscle does CN 4 innervate and what movements does it control?
Superior oblique muscle of the eye
Depression, adduction and internal rotation
What will I observe in a patient with CN 6 palsy?
Eye will be adducted due to denervation of lateral rectus muscle that abducts the eye (look sideways)
Which muscle is innervated by CN6 and what movement of the eye does it control?
Lateral rectus
Abduction
LAB!!
Which nerve innervates TASTE of anterior 2/3 and posterior 1/3 + circumvallate papillae of the tongue?
Anterior 2/3: Chorda tympani which is a branch of the facial nerve
Posterior 1/3: CN 9, glossopharyngeal nerve
Which nerve innervates TASTE of anterior 2/3 of the tongue?
Chorda tympani which is a branch of the facial nerve, CN 7
Which nerve innervates TASTE of posterior 1/3 + circumvallate papillae of the tongue?
CN 9, glossopharyngeal nerve
Which nerve innervates the cricothyroid muscle?
External laryngeal nerve
Which nerve innervates the muscles of the soft palate?
*There is one exception
CN 10, vagus nerve
Except tensor palatini which is innervated by mandibular nerve (V3)
Which is the muscle of the pharynx not innervated by pharyngeal branches of the vagus nerve?
Stylopharyngeus which is innervated by CN 9, glossopharyngeal
Which artery is the recurrent laryngeal nerve closely related to?
Inferior thyroid artery
How can I tell if there is a CNX palsy?
Uvula deviation: will deviate away from affected side.
Because CNX innervates muscles of the soft palate (esp levator palatini) -> elevates the soft palate.
Denervation -> no elevation of affected side + unopposed pull and elevation of unaffected side = deviation away from affected side
Which muscle of the larynx is closely related to voice production and why?
Posterior cricoarytenoid muscle which abducts the vocal folds
Which nerve, if affected, will result in hoarseness in voice?
Recurrent laryngeal nerve because it innervates the posterior cricoarytenoid muscle
How do I check for CNXII palsy?
Tongue deviation because CNXII innervates the genioglossus muscle which contracts to protrude the tongue.
Denervation means that one side of the tongue protrudes and the other doesnt, hence causing deviation towards the affected side.
Which nerve innervates the muscles of the tongue?
*Name the exception
CN 12 hypoglossal
Innervates all except palatoglossus which is innervated by CNX vagus
**What will I see in a patient with CN3 palsy?
- Ptosis due to impaired levator palpebrae superioris
- Mydriasis (pupils dilate) due to impaired sphincter pupillae
- Diplopia due to uncoordinated eye movements
Which CN does pupillary light reflex test for?
2,3
Which CN does accommodation test for?
2,3,4,6
Does the trigeminal motor nucleus receive bilateral or unilateral UMN influence?
Bilateral
What CN does corneal reflex test?
5,7
What parasympathetic component are you trying to elicit in a corneal reflex and what nerve innervates it?
Production of tears by lacrimal gland
Parasympathetic innervation is by CN 7
Describe the motor innervation of the face
For face, the upper half receives bilateral UMN influence while the lower half only receives contralateral UMN influence.
Patient presents with ipsilateral half of face weakness and numbness. What kind of lesion does he have?
LMN lesion - likely palsy of the facial nerve
Patient presents with lower half of the face symptoms (ie. loss of nasolabial, drooping corner of the mouth). What kind of lesion does he have?
UMN of the facial nerve lesion
What is the main muscle of the tongue that protrudes it?
Genioglossus
Name a key branch of the ophthalmic nerve and what muscle does run superiorly to?
Frontal nerve
Sits on top of the levator palpebra superioris muscle which raise and hold the upper eyelid open
Describe the visual processing pathway
- Photoreceptor (undergo phototransduction)
- Optic nerve
- Optic chiasm
- Synapse at lateral geniculate nucleus of thalamus
- Optic radiation
- Primary visual cortex in the occipital lobe
What is the function of the vestibular nerve and which CN is it a branch of?
CNVIII
Transmit vestibular information aka balance, spatial awareness and coordination
Name the contents of the carotid sheath
Vagus nerve
ICA
IJV
Describe how the vagus nerve branches out
Vagus
-> superior laryngeal nerve & recurrent laryngeal nerve
SLN -> external & internal LN
Which branch of the vagus nerve loops around which structure?
Recurrent LN
Left -> arch of aorta
Right -> right subclavian artery
Describe the trajectory of CNXII
Passes inferior to the angle of mandible and **CROSSES OVER THE ICA AND ECA to enter the tongue
Which CN are found in the cavernous sinus?
CN 3,4,6,V1,V2
Explain why lesions in the brain tend to cause unilateral CONTRALATERAL muscle weakness
Can be explained by the corticospinal tract which decussates at the medulla.
Hence, motor innervation of the left side of the body decussates and goes to the right primary motor cortex.
Infarct to the right PMC will thus cause contralateral left sided muscle weakness
Patient has a stroke. How do you expect the distribution of their muscle paralysis to be?
Unilateral & contralateral
Patient has UMN signs and also presents with aphasia and hemineglect. Where is the lesion likely to be?
Cerebrum/cerebral cortex
Patient has UMN signs and also presents with ataxia, dysmetria and dysdiadokinesis. Where is the lesion likely to be?
Cerebellum
What is the most common environmental cause of cerebellar dysfunction?
Chronic alcoholism
Which sensory pathway is likely affect in a medial brainstem injury and hence what patient present with?
DCML
Patient likely to present with loss of sensation of vibration and proprioception in the CONTRALATERAL side of the body
Patient presents with ophthalmoplegia, dysphagia and deviation of the tongue. They also complain of loss of sensation of vibration and proprioception in one side of their body.
Where is the lesion?
UMN
Brainstem - medial
- CN deficits
- DCML tract affected
Patient presents with miosis, ptosis and anhidrosis. They also complain experiencing a loss of sensation of pain and temperature in one side of their body.
Where is the lesion?
UMN
Brainstem - lateral
- Sympathetic outflow by superior cervical ganglion
- Spinothalamic tract affected
Which sensory pathway is likely affect in a lateral brainstem injury and hence what patient present with?
Spinothalamic
Loss of sensation of pain and temperature in the contralateral side
Patient presents with miosis, ptosis and anhidrosis. What condition do you suspect?
Horner’s syndrome
What will I expect to see in patients presenting with spinal cord lesions?
BILATERAL muscle weakness from the level of lesion down.
LMN signs at the level of lesion and UMN signs for all levels BELOW the lesion
If I have an anterior cord lesion, which sensory tract is affected and how will patient present?
Spinothalamic tract
Bilateral loss of sensation of pain and temperature from the level of lesion down
If I have a posterior cord lesion, which sensory tract is affected and how will patient present?
DCML
Bilateral loss of sensation of vibration and proprioception
What is the most common environmental cause of posterior cord syndrome?
B12 deficiency
** What happens if there is a lesion to a lateral half of the spinal cord?
Affect both DCML and spinothalamic
Motor (corticospinal) also affected.
**Loss of pain and temperature in the CONTRALATERAL side
IPSILATERAL loss of sensation of vibration and proprioception
What are some signs I will sign in cauda equina syndrome?
- Bilateral weakness in lower limbs
- LMN signs - hypotonia & absent reflexes
- Fasciculations
- Urinary incontinence due to S2-4 involvement
What is a sign of peripheral neuropathy?
Numbness, tingling and/or weakness with a glove and stocking distribution - the entire hand and feet are affected
What is the most common cause of peripheral neuropathy?
DIABETES MELLITUS!!!
What is a key differentiating symptom of NMJ conditions from the other neurological conditions?
Fatigability!!
Movements gets progressively weaker the more it is repeated.
Ocular weakness - drooping eyelids, double vision, difficulty keeping eyes open
Name a NMJ disorder and briefly state its pathogenesis
Myasthenia gravis
Ach receptor autoantibodies block and damage the Ach receptors
Will a patient with NMJ have abnormal or normal reflexes?
Normal reflexes
No sensory abnormalities as well (ie. no tingling/numbness)
Name some UMN signs
- Hypertonia
- Clasp knife rigidity
- Hyper reflex
- Upgoing plantars
- Protonator drift
Name some LMN signs
- Hypotonia
- Guttering (visible and hollow grooves due to severe muscular atrophy)
- Absent reflexes
- Downgoing plantars
- Fasciculations
Explain why does fasciculations occur
Denervation (loss of nerve supply to the muscle) results in muscle wasting.
Because of this loss, the muscles compensate by becomng hyper excitable -> uncontrollable twitches
What is the nutritional deficiency associated with peripheral neuropathy?
Vitamin B12 deficiency
At which level does the spinal cord end?
L1/L2
Is the cauda equina part of the spinal cord? Hence, if there is a lesion, will there be UMN or LMN signs?
No, it is not part.
Hence it is considered a bundle of peripheral nerves and will have LMN signs
Which space in the brain contains CSF?
Subarachnoid space between arachnoid and pia maters
At which level is lumbar puncture/spinal tap done?
L4/5
List the sensations transmitted by DCML
- Vibration
- Conscious propriocetion
- Fine/discriminative touch
List the sensations transmitted by the spinothalamic tract
- Pain
- Temperature
- Unconscious proprioception
- Crude touch
Which part of the spinothalamic tract transmit pain and temperature?
Lateral
Which part of the spinothalamic tract transmits crude touch and pressure?
Anterior
** At what level does the spinothalamic tract decussate?
At point of entry into spinal cord so decussate at spinal cord
** At which level does DCML deccusate?
Medulla oblongata
What is the function of pyrimidal motor tracts?
Transmit information about VOLUNTARY movements from the brain to the effectors
Where does the corticospinal tract decussate?
Medulla oblongata
Then it descends on contralateral side of spinal cord as lateral corticospinal tract
Name the UMN and LMN part of the corticospinal tract respectively
UMN: cerebral cortex
LMN: motor nuclei in ventral horn of spinal cord
Most LMNs recieve bilateral influence from UMNs, with the exception of:
- Part of the facial motor nucleus which innervates the lower half of the the fac
*recall that the lower half of the face recieves only contralateral UMN influence - Hypoglossal nucleus recieves mainly contralateral UMN influence
What is the function of extrapyrimidal tracts in motor pathways?
Transmit information about involuntary and automatic muscle control (eg. muscle tone, balance, posture and locomotion)
Name the 4 extrapyrimidal tracts
Reticulospinal
Vestibulospinal
Rubrospinal
Tectospinal
Patellar reflex test which nerves?
L4/5
Achilles reflex test which nerve?
S1
Which cranial nerve exits from the pons?
Trigeminal CN 5
Which cranial nerve exits from the midbrain?
Oculomotor CN3
Trochlear CN4
What does a positive Rinne’s test suggest? (ie. bone > air conduction)
Sound is transmitted better within the inner ear than in the external ear canal
=> Conductive hearing loss
=> External/middle ear pathology
Patient complains of right hearing loss. Upon conducting Rinne, it is found to be negative (ie. air > bone conduction).
When Weber’s test is done, left ear hears the sound louder than right.
Name the type of pathology
Sensioneural hearing loss
Pathology lies within the inner ear or with cochlear nerve transmission.
Patient complains of right hearing loss. Upon conducting Rinne, it is found to be positive (bone > air).
When Weber’s test is done, right ear hears the sound louder than left.
Name the type of pathology
Conductive hearing loss
Pathology lies within the external or middle ear.
