Neuroanatomy Flashcards
What makes up the anterior circulation of the brain?
Anterior cerebral artery Choridial artery Anterior communicating artery Internal carotid Middle cerebral artery
What makes up the posterior circulation of the brain?
Posterior communicating artery Posterior cerebral artery Vertebral arteries Anterior spinal artery Basilar artery Superior cerebellar artery Anterior inferior cerebellar artery Posterior inferior cerebellar artery
What makes up the circle of Willis?
Posterior cerebral artery Posterior communicating arteries Internal carotids Middle cerebral arteries Anterior cerebral artery Anterior communicating arteries
What does the anterior cerebral artery supply?
Frontal lobe (medial part) Corpus collosus Anterior limb of internal capsule Part of sensory/motor homunculus that innervates foot/leg Caudate and globus pallidus
What can you get with an anterior cerebral artery stroke?
Contra lateral foot/leg paralysis or sensory loss
Trans cortical aphasia
Bilateral infarction results in abulia (inability to read but can still write), urinary incontience, paraparesis or quadriparesis
Infarction of ACA is usually well tolerated due to good collaterals
What does the middle cerebral artery supply?
Bulk of the lateral cortical hemisphere
Brocas and wernickes speech centres
Deep branches to basal ganglia and internal capsule
What are symptoms of an MCA occlusion?
Paralysis and sensory loss of contra lateral face/arm/leg
Expressive and receptive aphasia (dominant hemisphere)
Contralateral homonymous upper quadrantopia (due to forward radiaton of optic fibres into temporal lobe)
Paralysis of conjugate gaze to other side (frontal eye centre)
Agnosia/apraxia (non-dominant hemisphere)
What is agnosia?
Inability to recognise objects, shapes, people, sounds and smells
What is apraxia?
Inability to carry out learned purposeful movements
What is a lacunar stroke?
Occlusion of one of the small penetrating branches of the mca leading to a small stroke in the internal capsule which can lead to a large defect due to the concentration of fibres there
Typically results in pure motor or sensory stroke but can result in both
What is amaurosis fugax?
Embolic phenomenon to the ophthalmic artery which branches off from the internal carotid, signifies symptomatic internal carotid diseae
Patients complain of a curtain moving across their vision
What does the posterior cerebral artery supply?
Occipital lobe
Infero-medial temporal lobe
Large portion of thalamus
Upper brainstem (midbrain)
Symptoms of posterior cerebral artery occlusion?
Peripheral territory
- homonymous hemianopia
- cortical blindness
- memory impairment
- visual hallucinations
Central territory
- thalamic syndrome (sensory loss, spontaneous pain, dysaasthesias)
- chorea, hemiballismus, intention tremor
- contra lateral hemiplegia
- oculomotor nerve palsy (webers syndrome)
What causes lateral medullary syndrome?
Usually occlusion of the vertebral artery but can occur from occlusion. Of the posterior inferior cerebellar artery
What is lateral medullary syndrome also known as?
Wallenburgs syndrome
What are the symptoms of lateral medullary syndrome?
Vertigo Numbness of ipsilateral face and limbs Contra lateral pain and temperature loss Ipsilateral Horners syndrome Dysphasia Diplopia Hoarseness
What percent of strokes involve the posterior circulation?
20%
What does the superior cerebellar artery supply?
Superior half of cerebellum
Midbrain (parts of)
Spinothalamic tracts
Symptoms of a superior cerebellar artery occlusion?
Ataxia Dizziness/vomiting/nystagmus Ipsilateral paralysis of conjugate gaze Ipsilateral horners syndrome Skew deviation Contra lateral impaired pain and temp (spinothalamic) and proprioception/vibration/light touch (medial lemniscus)
What does the posterior inferior cerebellar artery supply?
Inferior surface of cerebellum and inferior cerebellum peduncle
Sympathetic tracts
Vestibular nucleus
Descending tract of the 5th nerve
Nucleus ambiguous (carries fibres of 9 and 10th nerves)
Symptoms of posterior inferior cerebellar artery occlusion?
Ataxia
Ipsilateral facial pain and temp loss (Vth nerve nucleus)
Contra lateral pain and temp loss on body
Dysphonia/dysphagia (nucleus ambiguous)
Vertigo/nausea/vomiting/nystagmus
What does the anterior inferior cerebellar artery supply?
Anterior inferior surface of cerebellum
Flocculus
Middle cerebellar peduncle
Inferolateral portion of pons
What does occlusion of the anterior inferior cerebellar artery cause?
Vertigo/vomiting/nystagmus/hearing loss (8th nerve nucleus)
Dysarthria
Ataxia/falling to side of lesion
Contra lateral loss of pain and temp
What does the basilar artery supply?
Pons (corticospinal tract and deep nuclei)
Superior and anterior cerebellum
Middle and superior cerebellar peduncles
Vestibular nuclei
Symptoms of complete basilar artery occlusion?
Bilateral long tract signs (motor and sensory) plus cerebellar signs plus cranial nerve signs
What does locked in syndrome imply?
Complete infarction of pons and lower midbrain
Leads to preserved consciousness with quadriparesis and cranial nerve signs
What makes up the basal ganglia?
Striatum (caudate and putamen)
Subthalamic nuclei
Globus pallidus (interna and externa)
Substantia nigra
What does the indirect pathway through the basal ganglia do?
Inhibits movement
What does the direct pathway through the basal ganglia do?
Excites movement
What is the main inhibitory neurotransmitter?
GABA
What is the main excitatory neurotransmitter?
Glutamate
What is the role of the thalamus?
Main relay centre for most fibres travelling to and from the cortex - motor and sensory
Also has a role in sleep/wake and consciousness
