Neurology Flashcards
Name the meninges in order
Dura mater
Arachnoid mater
Pia mater
Which meninge has two layers which surround the venous sinuses?
Dura mater
Has a periosteal layer and a meningeal layer.
Which meninge contains the cerebrospinal fluid?
Arachnoid mater
Which meninge is tightly bound to the surface of the brain?
Pia mater
Which fascial layers divide the brain into sections? What is their function? What are they made of ?
Falx cerebri
Tentorium cerebelli
Prevent brain rotating within the skull
Made of reflections of dura mater
Which bony ridge does the falx cerebri attach onto?
Crista Galli of ethmoid
What is the blood supply to the scalp?
Aponeurosis of superficial temporal arteries and occipital arteries
Why does the scalp bleed so heavily? Why does the bone underneath not suffer from necrosis?
It is an Aponeurosis direct from external carotid.
The vessels can’t constrict because they are tightly bound to connective tissue
Bone underneath supplied by middle meningeal arteries
What type of bleed from which vessel usually causes an extradural haematoma?
Forceful arterial - usually middle meningeal
What type of bleed from which vessel usually causes an subdural haematoma?
Venous - veins between brain and venous sinuses
What type of patient is particular risk factor for a subdural haematoma?
Elderly with dementia.
Brain atrophies leaving longer sections of veins to sinuses exposed. Smaller brain also means more rotation in the cranial cavity so greater shearing forces.
How would you identify a sub arachnoid haemorrhage?
Pinkish CSF
Mri covered in white
Give 3 functions of cerebrospinal fluid.
Buoyancy and reduced weight
Homeostasis
Mechanical protection
How is CSF produced?
Choroid plexus in the lateral ventricles filters blood
Describe the flow of cerebrospinal fluid through the nervous system.
Produced in lateral ventricles - foramen of monro - 3rd ventricle - cerebral aqueduct - 4th ventricle
Then either - spinal canal or medial and lateral apertures to sub arachnoid space
Drains back to venous sinuses through arachnoid villi
What does a yellowish CSF indicate?
Infection eg meningitis
Which bacteria are implicated in meningitis?
Streptococcus pneumoniae
Or
Neisseria meningitidis
Why is meningitis so dangerous?
Inflammation and oedema raises intracranial pressure
Risk of decreased perfusion and/or cranial herniation (coning)
Give 4 key diagnostic symptoms of meningitis other than fever and headache.
Photophobia
Confusion
Stiff neck
(Later) rash due to sepsis
In which condition is congenital hydrocephalus common? Why?
Spina bifida
Notochord does not close properly so ventricles not complete.
Struggle to maintain pressure of CSF so excess is produced
Name the layers of the scalp
Skin Connective tissue Aponeurosis Loose connective tissue Periosteum
What are the 3 main arteries which are supplied by the circle of Willis?
Anterior middle and posterior cerebral arteries
Which areas of the brain are supplied by the anterior, middle and posterior cerebral arteries?
Anterior - medial full thickness strip, as far back as the occipital lobe
Middle - most of parietal and temporal lobes
Posterior - occipital lobe and inferior temporal lobe
Give 3 key functions of the frontal lobe
Executive function
Decision making
Motor function
Give 3 key functions of the parietal lobe
Somatosensory
Spatial awareness and perception
Broca’s speech
Give the key function of the occipital lobe
Primary visual cortex
Give 3 key functions of the temporal lobe
Wernicke’s - language
Hearing
Memory - hippocampus
What are the 3 main arteries that supply the brain?
2 internal carotids Vertebral artery (-basilar)
What do the external carotids supply?
Facial
Maxillary - middle meningeal (skull and meninges)
Superficial temporal - (scalp)
Where is the carotid sinus located? What is its clinical significance? What is its nerve supply?
Bifurcation of the common carotid
Location of baroreptors
Innervated by Glossopharyngeal
Where is atheroma build up common in the head and neck? Why?
Carotid sinus due to turbulent flow of blood
Where are intracerebral aneurysms most common? Why are they dangerous?
Circle of Willis
Risk of rupture
Give 4 broad causes of stroke
Thrombus
Embolus eg from carotid thrombus
Hypoperfusion eg in shock
Haemorrhage/ haematoma causing hypoperfusion and pressure necrosis
Which vein is used to measure jugular venous pressure (JVP)? Why?
Internal jugular vein
Drains closest to right atrium and pulsatile due to valve in inferior bulb.
Pulsation level gives good approximation of right atrial pressure
Where do the dural venous sinuses drain to?
Internal jugular vein
Where does blood from the scalp and face drain to?
Follows arteries to internal and external jugular veins
Which 2 disorders are caused by the failure of the notochord to fuse?
Cranially - anencephaly
Caudally - spina bifida
How can incidence of spina bifida be reduced?
Folic acid taken prior to conception and during the first trimester
How is the cauda equina formed?
Vertebral column grows faster than the spinal cord. The nerve roots below L1 are forced to extend.
What is cauda equina syndrome? How is it caused?
Trauma to L3/L4 affects S3-S5 dermatomes because the roots of these dermatomes start higher up.
Leads to saddle anaesthesia
Caused by trauma eg epidural or lumbar puncture.
Where is the correct site of a lumbar puncture? Why?
L3-L5 because it is below the end of the spinal cord
What causes the sulci and gyri of the brain?
Growth within the fixed cranial cavity
What is the prosencephalon? What are its derivatives?
Forebrain
Telencephalon - cortex
Diencephalon - thalamus
What is the mesencephalon? What are its derivatives?
Midbrain - midbrain stuctures
What is the rhombencephalon? What are its derivatives?
Metencephalon - pons and cerebellum
Myelencephalon - medulla
Where do neural crest cells arise? How are they formed?
Cells that arise on the lateral border of the neural tube.
Formed by epithelial to mesenchyme transition.
What are the derivatives of neural crest cells?
Lots of types of specialised cells
Eg Schwann, glia, ganglia, melanocytes, smooth muscle etc
Which types of embryological cells are most sensitive to alcohol?
Neurectoderm - particularly neural crest cells
What are the derivatives of the 1st pharyngeal arch?
Nerve - trigeminal Cartilage - mandible Artery - none Pouch - auditory canal Cleft - tympanic membrane
What are the derivatives of the 2nd pharyngeal arch?
Nerve - facial Cartilage - stapes, styloid, hyoid Artery - none Pouch - palatine tonsils Cleft - none
What are the derivatives of the 3rd pharyngeal arch?
Nerve - Glossopharyngeal Cartilage - none Artery - internal carotid Pouch - thymus and parathyroid Cleft - none
What are the derivatives of the 4th pharyngeal arch?
Nerve - vagus (superior laryngeal) Cartilage - epiglottis, thyroid, cricoid Artery - aortic arch, brachiocephalic, subclavian Pouch - thyroid gland Cleft - none
What are the derivatives of the 6th pharyngeal arch?
Nerve - Vagus (recurrent laryngeal) Cartilage - arytenoid Artery - pulmonary arteries Pouch - none Cleft - none
What is the path of the recurrent laryngeal nerve on the left and right? Why is it like this?
Forms from the 6th arch so has to loop around the 4th arch to get where it wants
On the right that is just the subclavian artery
On the left that is the arch of the aorta and the ductus arteriosus
How does the oral cavity develop embryologically?
Stomatadeum contains buccopharyngeal membrane
No mesoderm so obliterated
How does the nose develop embryologically?
Nasal placodes in the frontonasal prominence grow into pits.
They are pushed medially by the growth of the maxillary prominence below.
The nasal septum grows down to join the palate
How does the palate develop embryologically?
Fusion of nasal pits in frontonasal prominence forms primary palate - philtrum, four incisors and lip.
Maxillary palatal shelves from 1st arch grow into midline to form secondary palate.
All fuse
How do the eyes develop embryologically?
Outgrowth of diencephalon on side of head
Pushed medially by growth of facial prominences
How do the ears develop embryologically?
Auditory canal develops in 1st cleft in neck
Auricle grow from 2nd arch
All pushed up and in by growth of mandible
What is the cause of a cleft lip / palate?
Lip - failure of primary and secondary palate to fuse together
Palate - as above plus the failure of palatal shelves to meet in midline
What are the anterior and posterior pituitary gland derived from?
Anterior - rathke’s pouch - pinched off ectoderm
Posterior - infundibulum - pinched off neuroectoderm
Where does the thyroid originally develop? Where does it descend to? What is the clinical significance of this?
Foramen cecum at 2nd arch
To level of 4th arch
Can leave ectopic thyroid behind
What is the function of the dorsal column?
Fine touch, vibration and conscious proprioception
Where does the dorsal column decussate?
Medulla oblongata
Where are the cell bodies of the 1st, 2nd and 3rd order neurons of the dorsal column?
1st - dorsal root ganglion
2nd - nucleus cuneatus/ gracilis
3rd - thalamus
Where are the cell bodies of the 1st, 2nd and 3rd order neurons of the spinothalamic tract?
1st - dorsal root ganglion
2nd - dorsal horn
3rd - thalamus
Where does the spinothalamic tract decussate?
Spinal cord
What is the function of the spinothalamic tract?
Crude touch
Pressure
Pain and temperature
What is the function of the spinocerebellar tract?
Unconscious proprioception
Why is some sensory information unconscious?
Some proprioception is unconscious because it travels through the spinocerebellar tract and avoids the cortex.
What symptom would be associated with damage to the dorsal column? Give two possible causes.
Loss of conscious proprioception - ataxic gait
Vitamin B12 deficiency, neurosyphilis
What symptom would be associated with damage to the spinothalamic tract? Give a possible cause.
Loss of pain sensation
Syringomyelia - swelling of spinal canal pushes on spinothalamic where it decussates. Affects bilaterally.
What is the name given to the pattern of sensory loss in peripheral neuropathy? Give two possible causes.
Glove and stocking
Diabetic neuropathy
Guillain barre syndrome
What is Brown-Sequard syndrome?
Traumatic hemi section of spinal cord
Causes ipsilateral loss of dorsal column (fine touch)
Contralateral loss of spinothalamic (pain and temperature)