General Flashcards
With regard to spinal cord and cerebrum - what is dorsal and what is ventral
Dorsal = posterior/superior Ventral = anterior/inferior
3 layers of meninges
Dura (outermost)
Arachnoid
Pia (inner most)
What is Pia
Innermost layer of the meninges
On the surface of the brain and cant be separated from the brain
Microscopic layer, present between blood vessel and neurons also
What is dura attached to
Outermost layer of meninges
Firmly adherent to inside of the skull
Where do meningeal vessels arise
External carotid artery
Where are meningeal vessels found
Extradural space, between bones of the skull and dura
Example of blood vessels in cerebrum
Meningeal vessels
Bridging veins (between dura and arachnoid aka subdural space)
Circle of Willis
Where is circle of Willis
subarachnoid space (between arachnoid and pia)
What is white matter
Myelinated axons
What is grey matter
Cell bodies
no myelin sheaths
True or False:
There are no blood vessels deep to the pia
True
The pia forms part of the blood brain barrier
What cells myelinate axons in the brain or CNS
Oligodendrocytes
What cells myelinate axons in the PNS
Schwann cells
What are afferents
axons taking information towards the CNS e.g. sensory fibres
What are efferents
axons taking information to another site from the CNS e.g. motor fibres
Functions of frontal lobe
Voluntary movement on opposite side of body
Brocas area - speech and writing (found in dominant hemisphere i.e. left if right-handed)
Intellectual functioning
Thought processes
Reasoning
Memory
Functions of parietal lobe
Receives and interprets sensations, including pain, touch, pressure, size and shape and body-part awareness
Proprioception
Functions of temporal lobe
Understanding spoken word (WERNICKES)
Understanding sounds
Memory
Emotion
Functions of occipital lobe
Understanding visual images and meaning of written words
Where is CSF produced
Ependymal cells in choroid plexuses of lateral ventricles (mainly)
Where does CSF travel (describe ventricles of brain)
From lateral ventricles
Travels to 3rd ventricle via the interventricular foramen
From 3rd ventricle
Travels to 4th ventricle via the Cerebral Aqueduct
How does the 4th ventricle communicate with/pass CSF into the subarachnoid space
Median Foramen of Magendie
Two lateral Foramens of Luschka
Where is CSF absorbed after passing through subarachnoid space
Arachnoid granulations (VILLI) e.g. in superior sagittal sinus
What is hydrocephalus
Abnormal accumulation of CSF in ventricular system
Often due to a blocked cerebral aqueduct
Which spinal roots make up the sympathetic trunk
T1-L2
Give examples of what sympathetic nervous system stimulates
- Increases heart rate
- Increases force of contractions in the heart
- Vasoconstriction
- BronchoDILATION
- Reduces gastric motility
- Sphincter contraction
- DECREASED gastric secretions
- Male ejaculation
Give examples of what parasympathetic nervous system stimulates
- Decreases heart rate
- Decrease force of contraction
- Vasodilation
- BronchoCONSTRICTION
- Increases gastric motility
- Sphincter relaxation
- INCREASED gastric secretions
- Male erection
What are the parasympathetic cranial nerves and where do they run via
Oculomotor nerve CN3 - to pupil
Facial nerve CN7 - to salivary glands
Glossopharyngeal nerve CN9 - for swallowing reflex
Vagus nerve CN10 - to thorax & abdomen
What are upper motor neurones and where do they generally originate
The descending pathways and neurones that originate in the motor cortex
Control the activity of the lower motor neurones
What are lower motor neurones and where are their cell bodies located
Alpha motor neurones that directly innervate skeletal muscle that have cell
bodies lying in the grey matter of the spinal cord and brainstem
What is spasticity
Increased muscle tone
When muscles do not develop increased tone UNTIL they are stretched a bit and after a brief increase in tone, the contraction subsides for a short time (Clasp-knife phenomenon)
Give an example of a disease in which you could see spasticity
Parkinsons
What is rigidity
Increased muscle contraction
Continous
Resistance to passive stretch is constant
How many vertebrae are there in one spine
7 cervical 12 thoracic 5 lumbar 5 sacral 4 coccyx 33 in total
How many pair of spinal nerves are there
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccyx
Where do cervical spinal nerve segments exit the spine
(around) 1 vertebra HIGHER than their corresponding
vertebra
EXCEPT C8 which exits below C7
Where do thoracic spinal nerve segments exit the spine
Around 1 (-2) vertebra BELOW their corresponding vertebra
Where do lumbar spinal nerve segments exit the spine
3-4 vertebra BELOW their corresponding vertebra
Where do sacral spinal nerve segments exit the spine
around 5 vertebra below
Define dermatome
Area of skin supplied by a single spinal nerve - sensory
Sensory innervation of the little finger
Ulnar nerve
C8
Sensory innervation of the index finger
Median nerve
C7
Sensory innervation of the thumb
C6
Sensory innervation of the clavicle
C4
Sensory innervation of the nipples
T4
Sensory innervation of the medial side of arm
T1
Sensory innervation of the umbilicus
T10
Sensory innervation of the knee
L4
Sensory innervation of the perianal area
S4
Sensory innervation of the anus
S5
Define myotome
Volume of muscle supplied by a single spinal nerve
Spinal roots of phrenic nerve
C3,4,5
Spinal roots of sensation of small muscles of hand
T1
Spinal roots of innervation of the penis
S2,3,4 (keeps the penis off the floor)
In what direction are all X-rays/MRIs/CT scans take
From perspective of foot to head
Examples of Motor tracts
Lateral corticospinal tract Rubrospinal tract Olivospinal tract Vestibulospinal tract Tectospinal tract Anterior corticospinal tract
Examples of Sensory tracts
Fasciculus gracilis (more medial than cuneatus) Fasciculus cuneatus Posterolateral tract Intersegmental tract Posterior spinocerebellar tract Lateral spinocerebellar tract Anterior spinocerebellar tract Spino-olivary tract Spinorectal tract Anterior spinothalamic tract
Examples of Ascending tracts
Dorsal/Medial lemniscal columns
Spinothalamic tract
Spinocerebellar tract
Which tracts are involved in Dorsal/Medial Lemniscal ascending columns
Fasciculus cuneatus
Fasciculus gracilis
What sensations are detetcted/carried by Dorsal/Medial Lemniscal ascending columns
Proprioception
Vibration
Fine touch
Where does fasciculus cuneatus carry information to?
Lateral (one in spinal tract)
Carries information from UPPER body to the cuneate tubercle in the medulla oblongata
Where does fasciculus gracilis carry information to?
Medial
Carries information from LOWER body to the gracile tubercle in the medulla oblongata
Dorsal/Medial Lemniscal ascending columns - describe pathway after medulla oblongata
Decussates here (in medulla) to become the medial lemniscus then ascends to the thalamus then to SOMATOSENSORY cortex
What sensation is carried by the lateral spinothalamic tract
Pain and Temperature
What sensation is carried by the medial/anterior spinothalamic tract
Crude touch
Describe spinothalamic tract ascending pathway
Decussates soon upon entry into spinal cord (by 1/2 segments)
Ascends to the thalamus (unlike other sensory modalities that travel to the cortex)
PAIN reaches consciousness in the THALAMUS
What information is carried via the posterior spinocerebellar tract and to where
carries information on Proprioception
to the IPSILATERAL INFERIOR Cerebellar Peduncle
What information is carried via the anterior spinocerebellar tract and to where
carries information on Proprioception
to the CONTRALATERAL SUPERIOR cerebellar peduncle
Where do descending tracts originate
Cerebral cortex and brainstem (upper motor neurones)
2 types of descending pathways
Pyramidal
Extrapyramidal
Features of pyramidal descending pathways
where they originate, decussate etc
2 neurone pathway
Originates in cerebral cortex of cranial nerve nucleus
DECUSSATE in the Medulla and descend CONTRAlaterally
(also means neurones innervating our axial muscles (muscles of head and trunk) mostly do not decussate)
Synapses with the cell bodies of the ventral horn of the spinal grey matter
Example of pyramidal descending pathway
Corticospinal tract
Features of extra-pyramidal descending pathways
origin, function
- Originate in the brainstem and carry motor fibres to the spinal cord
- Responsible for involuntary autonomic control of all musculature
Examples of extrapyramidal descending pathways
Rubrospinal tract
Tectospinal tract
Vestibulospinal tract
Function of corticospinal tract (what do medial and lateral ones innervate)
Transmits control of voluntary muscles (motor)
Lateral (75%) - limb muscles
Medial (25%) - axial muscles (head and trunk muscles needed to keep upright etc)
Pathway of corticospinal tract
Transmits control of voluntary
muscles (motor)
Originates from the contralateral motor cortex
• Lateral corticospinal tract
(75%): pyramidal (MEDULLARY)
DECUSSATION - limb muscles
• Medial (25%): DECUSSATES as it leaves via the anterior white commissure (a bundle of nerve fibres that cross the mid-line of the spinal cord) - axial muscles
• UMN go from cortex to ventral horn; Neurones (cell bodies) located in the ventral horns project to limb and
axial muscles - these are the lower motor neurones (LMN)
Where can an UMN lesion occur
Upper motor neurones (UMN) originate in the motor cortex - a UMN lesion can occur anywhere from the cortex all the way down to the ventral horn
Functions of vestibulospinal tract
Muscle tone, balance and posture (innervates antigravity muscles)
Where does vestibulospinal tract originate
Vestibular nucleus (CN8)
Which of these decussates and where:
Rubrospinal tract
Tectospinal tract
Vestibulospinal tract
Tectospinal and Rubrospinal tracts decussate at MIDBRAIN thus is CONTRAlateral
Vestibulospinal tract is NON-decussating thus IPSIlateral
What is brown-sequard syndrome
Hemi-section of spinal cord
Features of brown-sequard syndrome
- Ipsilateral loss of; proprioception, motor & fine touch
- Contralateral loss of; pain, temperature & crude touch
Explain features of brown-sequard syndrome
- Ipsilateral weakness (i.e. less motor etc.) below the lesion - due to damage to the ipsilateral descending motor corticospinal tract (decussated at the medulla already)
- Ipsilateral loss of dorsal column proprioception below lesion - sine the ascending tracts are damaged before they could decussate in the medulla
- Contralateral loss of spinothalamic pain & temperature below the lesion since spinothalamic fibres decussate just after entering cord within the spinal cord
Level of UMN and LMN lesions
UMN - above T10 vertebral or T12 spinal segment
LMN - below T10 vertebral or T12 spinal segment
UMN and LMN lesions: Effect on bladder
UMN - spastic bladder + urge incontinence
LMN - flaccid bladder + overflow incontinence
UMN and LMN lesions: Tone differences
UMN - Hypertonic (increased)
LMN - Hypotonic (decreased)
UMN and LMN lesions: type of paralysis
U (or alpha) MN - Spastic paresis
LMN - Flaccid paralysis
UMN and LMN lesions: Atrophy
UMN - No (only disuse) atrophy
LMN - severe atrophy
Names 12 cranial nerves in order and if sensory, motor or both and if parasympathetic
(Oh Oh Oh To Touch And Feel Very Green Velvet Ah Heaven) 1 Olfactory - Some 2 Optic - Say 3 Oculomotor Money (Para) 4 Trochlear - Matters 5 Trigeminal - But 6 Abducens - My 7 Facial - Brother (Para) 8 Vestibulocochlear - Says 9 Glossopharyngeal - Big (Para) 10 Vagus - Breasts (Para) 11 Accessory - Matter 12 Hypoglossal - More
Vestibulocochlear nerve - which is ipsilateral, which is contralateral
Vestibular - Ipsilateral
Cochlear - Contralateral
Cranial nerve brainstem nuclei location: Which cranial nerves have nuclei in midbrain?
3 and 4
Oculomotor
Trochlear
Cranial nerve brainstem nuclei location: Which cranial nerves have nuclei in pons?
5, 6, 7, 8 Trigeminal Abducens Facial Vestibulocochlear
Cranial nerve brainstem nuclei location: Which cranial nerves have nuclei in medulla oblongata?
9, 10, 11, 12 Glossopharyngeal Vagus Accessory Hypoglossal
Branches of trigeminal nerve
Ophthalmic nerve (V1) Maxillary nerve (V2) Mandibular nerve (V3)
What is Brocas area and where is it
Language (speaking and writing) area of the DOMINANT (normally left if right handed) FRONTAL LOBE
What can result from damage to Brocas area
Expressive aphasias
Difficulty forming words or sentences
Can understand what youre saying but can not express the words into meaningful language
What is Wernickes area and where is it
Comprehension area in DOMINANT (normally left if right handed) TEMPORAL LOBE and is responsible for understanding speech
What can result from damage to Wernickes area
Comprehension/receptive aphasias
Difficulty understanding spoken or written language, even though their hearing and vision are not impaired
Have fluent speech, but may scramble words do that their sentences make no sense (often adding unnecessary words or making own words)
Often unaware they’re not speaking in clear sentences
What is supplied by external carotid
Everything in head and neck except the brain
What vessel only supplies the brain
Internal carotid
What does Anterior Cerebral Artery supply
Supplies motor cortex and top of brain
If ischaemic stroke in ACA (anterior cerebral), what would be affected
Lower limbs
What does Middle Cerebral Artery Supply
Majority of outer surface of the brain
If ischaemic stroke in MCA (middle cerebral), what would be affected
Chin to hip
limb sparing
Whats does Posterior Cerebral Artery supply
Peripheral vision
If ischaemic stroke in PCA (posterior cerebral), what would be affected
Peripheral vision loss but no macular vision
What is 1st main artery to come off vertebral artery
Posterior Inferior Cerebellar Artery (PICA)
Therefore emboli present will likely enter the PICA
What is supplied by the Posterior Inferior Cerebellar Artery (PICA)
Medulla (CN 9, 10, 11, 12)
What can result from an emboli in the Posterior Inferior Cerebellar Artery (PICA)
Dysphagia Slurred speech Ataxia Facial pain Nystagmus Loss of pain and sensation on opposite side of body
What is the most common type of intercranial aneurysm
Berry aneurysms
Where do Berry Aneurysms occur
Most commonly at Anterior cerebral artery (ACA) and Anterior Communicating artery junction
Also at bifurcation of MCA, junction between Posterior Communicating A, MCA and Internal Carotid
What type of haemorrhage can result from a berry aneurysm and what is the main symptom
Subarachnoid haemorrhage
Thunderclap headache
(with the exception of left and right coronary arteries) What are 3 initial main branches of the aorta (at (carotid) arch) in order
Brachiocephalic artery
Left Common Carotid artery
Left Subclavian artery
What are 2 arteries form from the bifurcation of Brachiocephalic trunk
Right Subclavian artery
Right Common Carotid artery
Where do common carotid arteries bifurcate and into what?
Internal (larger than external) and External Carotid arteries
C4
(This bifurcation is at high risk of atherosclerosis)
What does the end of the Internal Carotid bifurcate into
Middle Cerebral artery
Anterior Cerebral artery
Segments of Internal Carotid Artery
Cervical
Petrous ICA
Cavernous sinus ICA
Supraclinoid (intradural) ICA
Which ICA segment penetrates the skull
Petrous ICA
penetrates the temporal bone and runs anteromedially int the carotid canal
Describe anatomical location of cervical ICA
Anterior and medial to internal jugular vein
Posterior and lateral to External Carotid artery at origin
Ascends behind then medial to external carotid artery
Branches of Petrous ICA
Caroticotympanic artery (small branch to middle/inner ear) Vidian artery (small connection to external carotid artery)
In violent sport, what part of the ICA can rupture
Cervical ICA is free
Petrous ICA is anchored/fixed in the skull
Cervical can rupture and can even dissect with extreme rotation
Anatomy of cavernous sinus ICA
Turns superiorly at foramen lacerum to enter the skull via the carotid canal, anterior to the jugular foramen
There it enters the cavernous sinus
Pierces dura at level of anterior clinoid process
What can happen if an aneurysm ruptures, past where the cavernous sinus ICA pierces the dura
Subarachnoid haemorrhage
Resulting in increased intracranial pressure
Branches of supraclinoid (intradural) ICA
Opthalmic artery
Superior hypophyseal arteries/trunk
Posterior communicating artery
Anterior choroidal artery
What does opthalmic artery supply
Orbit of eye
passes into optic canal
What does superior hypophyseal arteries/trunk supply
Supply pituitary gland, stalk, hypothalamus and optic chiasm
What does posterior communicating artery
Connects to anterior cerebral vascular supply of head and posterior brain stem supply of head
What does anterior choroidal artery supply
Choroid plexus Optic tract - vision Cerebral peduncle - sensory motor fibres Internal capsule Medial temporal lobe
What artery supplies ganglia and internal capsule
Lateral lenticulostriate arteries
From Middle Cerebral Arteries
Specifically what sturctures in cerebrum are supplied by anterior cerebral artery
Caudate nucleus and Internal capsule supplied by medial lenticulostriate arteries of anterior communicating artery of ACA
Genu of corpus callosum
Examples of intercranial vertebral artery branches
Anterior spinal artery
Small medullary perforators
Posterior inferior cerebellar artery (supplies medulla and inferior cerebellum)
Vertebral arteries unite to form what artery
Basilar arteries
What arteries branch off basilar artery
Pontine arteries
What 2 vessels arise from terminal (anterior) bifurcation of basilar arteries
Posterior cerebral artery
What specific structures are supplied by the PCA
Thalamus
Geniculate bodies
Cerebral peduncles
Tectum
Draw visual fields diagram
Pg 24
Which colliculus and which geniculate body relates to Visual field
Superior colliculus
Lateral geniculate body
(IM Auditory = Inferior colliculus + Medial geniculate body
Where does optic tract terminate
Lateral geniculate bodies
Which loop connects lateral geniculate body to visual cortex and results from lateral retinas sensing nasal visual fields
Meyers loop
What lobe does Meyers loop pass through
Temporal lobe
Which loop connects lateral geniculate body to visual cortex and results from medial retinas sensing temporal visual fields
Baums loop
What lobe does Baums loop pass through
Parietal
Which of these if false:
a - Fibres form the nasal portion of the retina (carrying the TEMPORAL VISUAL FIELDS) cross at the optic chiasm
b - Optic chiasm is located just anterior-superior to pituitary infundibulum
c - Lateral geniculate body is connected to visual cortex by the optic tract
c- Lateral geniculate body is connected to visual cortex by the optic radiation
Defect in left optic nerve
No light perception in the left eye
Defect of optic chiasm
Bitemporal hemianopia
Defect of left optic tract
Loss of vision of the temporal field of the left eye & the loss of the nasal field of the right eye
Homonymous Hemianopia
Defect of left Meyers loop
Carrying information from the inferior retina and thus the SUPERIOR VISUAL FIELD resulting in loss of vision in the superior nasal field of the left eye and the superior temporal field of the right eye
Right Homonymous Superior Quadrantopia
Defect of left Baums loop
Carrying information from the superior retina and thus the INFERIOR VISUAL FIELD resulting in loss of vision in the inferior temporal field of the right eye and the inferior nasal field of the left eye
Right Homonymous Inferior Quadrantopia
Pg26
Check visual field defects correct
Differences between UMN and LMN lesions
UMN: Strength lowers Tone increases (spastic) Superficial reflexes absent Increased reflexes (deep tendon reflexes) - Hyper-reflexia Slight loss in muscle mass Positive Babinski sign LMN: Strength lowers Tone decreases (flaccid) Fasciculations, Fibrillations, Reaction of degeneration Decreased reflexes (deep tendon reflexes) - Hypo-reflexia Decreased/atrophy muscle mass Negative Babinski sign