Brain Flashcards
What is an Arnold Chiari Malformation?
A condition affecting the brain. Consists of a downward displacement of the cerebellar tonsils through the foramen magnum causing non-communicating hydrocephalus as a result of obstruction of CSF outflow
Where do meningioma arise from?
The arachnoid “cap” cells of the arachnoid villi in the meninges
What structures do meningioma’s lie between
Falx and cerebral hemisphere
What are of the body is represented on the medial side of the motor area?
Lower limbs (feet nearest the midline)
What area is located in the pre-central gyrus of the brain?
The primary motor cortex
Which layer of meninges is a meningioma attached to?
The dura
What type of contrast is used for an MRI brain
Gadolinium
What is meant by ring enhancement?
An abnormal radiological sign on MRI or CT using radiocontrast.
On the image there is an area of increased density surrounded by a bright rim from concentration of the enhancing contrast dye
This enhancement may represent breakdown of the blood brain barrier and the development of an inflammatory capsule
What are the differential diagnoses for ring enhancement?
Metastasis
Abscess
Glioblastoma
Infarct (subacute phase)
Contusion
Demyelinating disease
Radiation necrosis or resolving haematoma
What is the aggressive form of glioma
Glioblastoma multiforme
How does CSF circulate
Produced by the choroid plexuses within the lateral ventricles > Interventricular foramen (Foramen of Monroe) > Third ventricle > aqueduct of sylvius > fourth ventricle > Foramen of Luschkam and Magendie > Subarachnoid space > arachnoid villi > superior sagittal sinus
What is the circle of Willis?
An anastomosis between the internal carotid arterties and vertebral arteries on the inferior surface of the brain
What is the circle of Willis formed from?
Anterior communicating artery
Anterior cerebral artery
Internal carotid artery
Posterior communicating artery
Posterior cerebral arteries and the termination of the basilar artery
What are the features of the vertebral arteries?
Enter the cranial canal via the foramen magnum
Lie in the subarachnoid space
Ascend on anterior surface of the medulla oblongata
Unite to form the basilar artery at the base of the pons
What are the branches of the vertebral arteries?
Posterior spinal artery
Anterior spinal artery
Posterior inferior cerebellar artery
What are the branches of the basilar artery?
Anterior inferior cerebellar artery
Labyrinthine artery
Pontine artery
Superior cerebellar artery
Posterior cerebellar artery
What are the branches of the internal carotid artery?
Posterior communicating artery
Anterior cerebral antery
Middle cerebral artery
Anterior choroid artery
What is the entry of the vertebral artery into the skull?
Vertebral artery enters the skull through the foramen magnum
It crosses transversely across the posterior arch of the atlas
What is the course of the vertebral artery?
Inside the skull, the 2 vertebral arteries pass upwards, forwards and medially in the subarachnoid space to reach the anterior aspect of the medulla oblongata, then they unite together at the lower border of the pons to form the basilar artery
What do the Vertebral and basilar arteries supply within the brain?
The vertebrobasilar artery system supplies the medulla, cerebellum, pons, midbrain, thalamus and occipital cortex
Which vein drains the dangerous area of the face?
Inferior ophthalmic vein
Where does the ICA enter the skull and what is it’s course?
Enters the skull via the carotid canal in the petrous part of the temporal bone
What branch is given off the ICA before the anterior and middle cerebral arteries?
Ophthalmic artery
What condition does a berry aneurysm lead to?
Subarachnoid haemorrhage
What are the signs of an MCA infarct?
Hemiplegia of the lower 1/2 of the contralateral face
Hemiplegia of the upper and lower extremities
Aphasia if in the dominant hemisphere
What is the anterior attachment of tentorium cerebelli?
Superior angle of the petrous part of temporal bone
Which blood vessel supplies the inner table of the temporal bone?
Middle meningeal artery
If there is a tumour in the precentral gyrus which bone should be penetrated to get to the tumour?
Parietal bone
Relationship between ICP and oculomotor nerve?
An increase in ICP leading to a oculomotor nerve palsy which leads to a dilated pupil
What are false localising signs?
Neurological signs which reflect dysfunction distant or remote from the expected anatomical locus of pathology. They occur in two major contexts - as a consequence of raised ICP or with spinal lesions
Which muscles are supplied by the oculomotor nerve?
Levator palpebrae superioris
Superior rectus
Inferior rectus
Medial rectus
Sympathetic fibres to Muller’s muscle
Inferior oblique
Sphincter pupillae
Paralysis of the oculomotor nerve leads to
THe eye being displaced downwards and outwards
Outward because the lateral rectus maintains muscle tone in comparison to the paralyed medial rectus as it is supplied by CN VI
Downwards because the superior oblique is un-anatgonised by the paralysed superior rectus, inferior rectus and inferior oblique
They will also have ptosis and mydriasis
What is the structure on which the oculomotor nerve is pressed against?
Petrous part of the temporal bone, attached border of the tentorium cerebelli
