Cerebral and cranial vasculature

Branches of the internal carotid artery: 

It starts with a few minor (irrelevant for MRCSA) ones - caraticotympanic, vividian, meningohypohyseal, inferolateral - then the main ones are:

1. Ophthalmic 
2. Posterior communicating 
3. Anterior choroidal 
4. Anterior cerebral 
5. Middle cerebral 

The first branch of the internal carotid artery as it emerges from the cavernous sinus is the ophthalmic artery.

Broca's aphasia

In Broca's aphasia, think MCA. Broca’s aphasia occurs due to infarction of the superior division of the dominant (usually left) MCA, affecting the inferior frontal gyrus. It is an expressive, non-fluent aphasia: comprehension is largely preserved but speech production is severely impaired. Patients understand simple sentences, but struggle to form words and sentences. Comprehension is in tact; repetition is poor. Their speech is slow, effortful, and telegraphic, limited to short phrases. Writing is also affected and mirrors the speech pattern: slow, effortful, and agrammatic.

Upper vs Lower Motor Neurone Lesions

Forehead sparing in a stroke happens because the frontalis (forehead muscles) are controlled by signals from both sides of the brain (bilateral corticobulbar innervation). In contrast, the muscles of the lower face get signals from only the opposite side of the brain (unilateral innervation). So, when a stroke damages the middle cerebral artery territory on one side of the brain, the forehead is spared because it still gets input from the other, healthy side of the brain whereas the lower facial muscles have unilateral innervation so lose their input and droop.

Branches of the subclavian artery:

Vit C+D to become A 

• V Vertebral
• I Internal thoracic 
• T Thyrocervical 
• C Costocervical 
• D Dorsal scapular 
• A Axillary  

The vertebral arteries arise from the first part of the subclavian arteries and enter the transverse foramina of the cervical vertebrae at C6. They ascend through the C6 to C1 transverse foramina, and enter the cranium via the foramen magnum to contribute to the posterior cerebral circulation (Circle of Willis).

Subclavian steal syndrome

Narrowing, usually from atherosclerosis, in the proximal part of the subclavian artery, just before the vertebral artery branches off. This blockage means blood destined for the brain is “stolen” and flows backwards down the vertebral artery to supply the arm instead. Thus in subclavian steal syndrome, retrograde flow is seen in the vertebral artery. The patient may notice dizziness and cramping pain in his arm when playing vigorous activity involving that limb. There may be a BP difference between the two arms of 15 mmHg and a bruit above the clavicle. The most appropriate investigation is an arterial duplex of the aortic arch and its branches.

PICA syndrome

A PICA stroke, aka wallenberg syndrome or lateral medullary syndrome, affects the lateral medulla and inferior cerebellum. A PICA stroke damages the lateral medulla to possibly cause:

• Contralateral loss of pain and temperature sensation in the body
• Ipsilateral loss of pain and temperature sensation in the face
• Ipsilateral limb ataxia, balance issues, vertigo, nystagmus due to loss of proprioceptive input from the inferior cerebellar peduncle and vestibular nuclei supplied by the PICA.
• Horner’s syndrome as descending sympathetic fibres may be affected.
• Dysphagia, dysarthria, hoarseness
• Ophthalmoplegia and hiccups may rarely occur if nearby cranial nuclei or respiratory centres are involved.

Branches of the external carotid artery:

• Superior thyroid
• Ascending pharyngeal
• Lingual
• Facial
• Occipital
• Posterior auricular
• Maxillary
• Superficial temporal

Stroke syndromes by arterial territory

📚 Exam-style questions

• Which of the following is the first branch of the internal carotid artery as it emerges from the cavernous sinus?
  • Anterior cerebral 
  • Middle cerebral
  • Anterior choroidal
  • Posterior communicating 
  • [[Ophthalmic::The ophthalmic artery is the first branch after the internal carotid exits the cavernous sinus.]]

• A man is undergoing stereotactic frame placement for radiosurgery on a cerebral AVM. The frame is secured using four pins through the scalp into the skull. During insertion of a posterior pin, arterial bleeding occurs. Which artery was most likely punctured?
  • Ascending pharyngeal
  • [[Occipital::The occipital artery of the external carotid artery runs superficially in the posterior scalp, at risk in posterior pin placements in stereotactic frames.]]
  • Posterior cerebral
  • Posterior communicating 

• During arch aortography, the vertebral artery would be seen to arise directly from which of the following?
  • Arch of the aorta 
  • Brachiocephalic artery
  • Common carotid artery
  • Internal carotid artery
  • [[Subclavian artery::The branches of the subclavian artery: Vit C+D to become A]]

• Vertebral artery is a branch from which?
  • 1^st part of the subclavian artery
  • 2^nd part of the subclavian artery
  • 3^rd part of the subclavian artery

• In subclavian steal syndrome, retrograde flow is seen in which artery?
  • Subclavian  
  • [[Vertebral::The vertebral arteries arise from the left/right subclavian artery, ascend through the C6 to C1 transverse foramina, and enter the cranium via the foramen magnum to contribute to the posterior cerebral circulation (Circle of Willis).]]
  • Internal carotid
  • Brachiocephalic  

• A man notices dizziness and cramping pain in his arm when playing squash. What is the most appropriate first investigation?
  • CT brain
  • Venous duplex of the neck
  • [[Arterial duplex of the aortic arch and its branches::Confirms the diagnosis of subclavian steal syndrome]]
  • CT Angiogram of the aortic arch and its branches 

• A man presents with paralysis of his right lower limb. Which arterial territory is most likely involved?
  • [[Left anterior cerebral::The ACA supplies the medial motor cortex, which controls the contralateral lower limb.]]
  • ((Left middle cerebral::Left MCA occlusion would affect the face and arm on the right side))
  • ((Right anterior cerebral::Right ACA occlusion would cause weakness in the left lower limb))
  • ((Right middle cerebral::Right MCA occlusion would affect the left face and arm, not right leg))
  • ((Right posterior cerebral::Right PCA occlusion would affect the visual cortex))

• A man has sudden right upper‑limb weakness and Broca’s aphasia. Which artery is most likely occluded?
  • ((Left anterior cerebral::Left ACA occlusion would affect right lower limb strength))
  • [[Left middle cerebral::Left MCA occlusion would affect the face and arm on the right side]]
  • ((Right anterior cerebral::Right ACA occlusion would affect left lower limb strength))
  • ((Right posterior cerebral::Right PCA occlusion would affect the occipital visual cortex))

• A patient presents with a middle cerebral artery blockage. What is the most likely presenting symptom?
  • [[Contralateral face weakness sparing the forehead::The MCA supplies the lateral frontal cortex, including Broca’s area of the dominant hemisphere’s language centre, and the contralateral upper limb and face more than the lower limb.]]
• ((Contralateral lower limb weakness::Contralateral lower limb weakness indicates ACA territory involvement))
• ((Ipsilateral gaze preference::Ipsilateral gaze preference may occur in MCA occlusion but it is not a hallmark feature))
• ((Dysphagia and hoarseness::Dysphagia and hoarseness indicates PICA territory involvement))
• ((Contralateral homonymous hemianopia::Contralateral homonymous hemianopia indicates PCA territory involvement))

• What differentiates a facial nerve lower motor neuron lesion from an upper motor neuron lesion in facial palsy?
  • [[Inability to raise eyebrow::The frontalis (forehead muscles) are controlled by signals from both sides of the brain (bilateral corticobulbar innervation)]]
  • ((Cannot blow cheeks out::Inability to blow cheeks out occurs in UMN and LMN lesions))
  • ((Loss of chin reflex::Loss of chin reflex indicates pyramidal tract involvement))
  • ((Cannot open mouth against resistance::Inability to open mouth against resistane occurs in Trigeminal CN V weakness, not facial CN VII))

• A man has trouble forming long sentences. Which artery is most likely occluded?
  • Anterior cerebral
  • Posterior inferior cerebellar
  • Posterior cerebral 
  • [[Middle cerebral::In Broca's aphasia, think MCA.]]

• A man has nystagmus, slurred speech, and cannot walk in a straight line. Diagnosis?
  • [[PICA syndrome::PICA syndrome causes ipsilateral cerebellar signs like ataxia, dysmetria, nystagmus, plus dysphagia, hoarseness]]
  • ((MCA occlusion::MCA occlusion causes contralateral face/arm weakness and sensory loss, aphasia, neglect, and gaze deviation))
• ((Lacunar syndrome::Lacunar syndrome describes a pure motor or pure sensory stroke in the absence of any cortical signs))
• ((Ophthalmic artery::Ophthalmic artery occlusion cause sudden painless monocular blindness; fundoscopy shows cherry-red macula with pale retina))

• A male presents with tremors, dysdiadochokinesia, and bilateral nystagmus. Which is the affected artery?
  • ((Anterior cerebral::ACA occlusion causes contralateral leg weakness & sensory loss, urinary incontinence, akinetic mutism, abulia))
  • ((Middle cerebral::MCA occlusion causes contralateral face/arm weakness and sensory loss, aphasia, neglect, and gaze deviation))
• [[Posterior inferior cerebellar::PICA syndrome includes ipsilateral cerebellar signs like ataxia, dysmetria, nystagmus, plus dysphagia, hoarseness]]
• ((Ophthalmic artery::Ophthalmic artery occlusion cause sudden painless monocular blindness; fundoscopy shows cherry-red macula with pale retina))

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