10.1 Vascular anatomy of the brain Flashcards
Which two arteries supply blood to the brain?
Internal carotid and vertebral
How does the carotid artery enter the cranium?
Ascends within the carotid sheath, enters the cranium through the carotid canal
How do the vertebral arteries enter the cranium?
Ascend the cervical vertebrae with transverse foramen, enters vertebral canal by penetrating the posterior atlanto-occipital membrane and enters the cranium through the foramen magnum
What is the anterior spinal artery and where does it run?
Occupies the anterior median sulcus and runs down the full extent of the spinal cord reinforced by segmental branches at each level of the spinal cord
Where would you find the posterior spinal arteries?
Posterolateral sulcus
What does the PICA supply?
Major territories in the medulla and cerebellum:
Lateral medulla before going to the back of the cerebellum
Choroid plexus of the 4the ventricle (secretes CSF)
Postero-inferior surface of the cerebellum
What are the branches of the basilar artery?
Anterior inferior cerebellar artery
Superior cerebellar artery
Pontine branches
What does the anterior inferior cerebellar artery supply?
Anterior part of inferior cerebellum and caudal pons
What does the superior cerebellar artery supply?
Supeior surface of the cerebellum, caudal midbrain and rostral pons
What separates the posterior and superior cerebellar arteries?
Tentori cerebelli (separates cerebellum form temporal lobe)
What do the pontine arteries supply and what is an important branch of these?
Supply the pons, the internal auditory/labrinthine artery supplies the inner ear - occlusion is associated with vertigo
What do the anterior spinal arteries and vertebral arteries supply in the lower medulla?
Lower spinal V nucleus and tract
Arcuate fibres and medial lemniscus
Spinothalamic tracts
Pyramids
What does the posterior spinal artery supply in the lower medulla?
Gracile and cuneate nucleus of DC system
What does the anterior spinal artery supply in the upper medulla
Pyramids (corticospinal tract)
Medial lemniscus (DC system)
Tectospinal (and medial long. fasiculus)
Hypoglossal nucleus
What does the PICA supply in upper medulla?
Vestibular nuclei Olivocerebellar fibres Spinal V nucleus Solitary nucleus and tract Nucleus ambigus Spinothalamic tract Descending sympathetic fibres
If you have an anterior spinal artery occlusion/bleed what will you get?
Medial medullary syndrome
C/L hemiparesis (pyramid)
C/L impairment of sensation of tactile discrimination, proprioception (medial lemniscus)
I/L paralysis of tongue muscles (hypoglossal n + nucleus)
If you have a PICA bleed/occlusion what will you have?
Lateral medullary syndrome (Wallenbergs)
- Dysphagia (n.ambiguus)
I/L loss of pain and temp to face (spinal V)
Vertigo, nausea, vomiting, nystagmus (vestibular nerve)
Horners syndrome (sympathetics)
I/L limb and gait ataxia (dorsal spinocerebellar, ICP and olivocerebellar)
C/L loss of pain and temp (spinothalamic)
What are the symptoms of Horners syndrome and wha causes it?
Ptosis, miosis, anhidrosis
Due to loss of sympathetic innervation
What is retained in locked in syndrome and why?
Oculomotor and trochlear nerve function
Hearing
The nuclei for the nerves involved are not affected - oculomotor in the midbrain and the cochlear nerves and superior olivary nerve are laterally placed on the pons
what does the posterior cerebral artery supply?
tectum, most of cerebral peduncle (except most medial), oculomotor nucleus and Edinger Westphal nucleus
What is the Edinger Westphal nucleus?
accessory oculomotor nucleus and is the parasympathetic pre-ganglionic nucleus that innervates the iris sphincter muscle and the ciliary muscle.
What will you get with an occlusion/bleed of the posterior cerebral artery (mid brain branches)?
Weber’s syndrome: necrosis of teh peduncle and oculomotor nerve
I/L opthalmoplegia, ptosis, dilation of pupil, no light response or accommodation (CN III nucleus ad nerve)
C/L paralysis of arm and leg (corticospinal)
C/L paralysis of lower face and tongue (corticobulbar)
What will you get with occlusion/bleed of posterior cerebral artery affecting the lemnisci and red nucleus?
Benedikts syndrome
C/L involuntary limb movements
C/L loss of sensation
Where does the internal carotid lie?
Immediately posterior to the optic nerve
What are the branches of the internal carotid artery and how do they end?
Opthalmic
Posterior communicating
Anterior choroidal
End by dividing into anterior and middle cerebral arteries
Where does the anterior cerebral artery run and what does it supply?
In the cingulate sulcus, just above corpus callosum as far as the parieto-occipital sulcus
Supplies the medial aspect of frontal and parietal lobes and a narrow strip adjacent to the inter-hemispheric sulcus
ALso supplies olfactory bulbs, tracts and anterior hypothalamus
Where does the middle cerebral artery run, what are its branches and what does it supply?
Runs laterally between frontal and temporal lobes to enter the lateral fissure
Subdivides into 2 major branches for the
1. frontal and anterior parietal lobes
2. temporal and posterior parietal lobes
Supplies lateral surface of the cerebral cortex including the frontal, parietal and antero-lateral occipital lobes and the insula
What will you get with bleed/occlusion of anterior cerebral artery?
C/L hemiplegia and somatosensory loss affecting the leg and food (paracentral lobe)
What will you get with bleed/occlusion of middle cerebral artery?
C/L hemiplegia and ocmatosensory of upper limb and head, aphasia, multiple sensory losses
What will you get with bleed/occlusion of posterior cerebral artery
C/L hemianopsia (damage to V1-3 and occipital cortex)
How is blood drained from the brain
Via the venous sinuses which is located between 2 layers of dura
Mostly via the sigmoid sinus > internal jugular vein
Cavernous sinus drains central face and orbit
