13. ICA, vertebrobasilar arteries, circle of willis

What 2 arterial systems supply the brain?

Internal carotid + vertebrobasilar systems.

Where does the vertebral artery originate?

Subclavian artery.

What is the key course of the vertebral artery?

C6–C1 transverse foramina → foramen magnum → cranial cavity.

What important cerebellar artery arises from the vertebral artery?

PICA (posterior inferior cerebellar artery).

What does PICA supply?

Inferior cerebellum + part of medulla.

How is the basilar artery formed?

Union of right + left vertebral arteries.

Where does the basilar artery run?

Basilar sulcus on ventral pons.

What are the major branches of the basilar artery?

AICA + SCA + PCA (+ small pontine branches).

What does AICA supply?

Anterior-inferior cerebellum.

What does SCA supply?

Superior cerebellum.

What are the terminal branches of the basilar artery?

Right + left posterior cerebral arteries (PCA).

Where does the ICA originate?

Common carotid bifurcation.

How does the ICA enter the skull?

Through the carotid canal.

What are the 4 parts of the ICA?

Cervical → Petrous → Cavernous → Cerebral.

What is the course of the cervical ICA?

Ascends in neck → no branches.

What is the course of the petrous ICA?

Through carotid canal in petrous temporal bone.

What is the course of the cavernous ICA?

Through cavernous sinus.

What is the cerebral part of the ICA?

Intracranial portion giving ophthalmic/cerebral branches.

What are the major intracranial branches of the ICA?

Ophthalmic + posterior communicating + anterior choroidal + superior hypophyseal + ACA + MCA.

What does the ophthalmic artery supply?

Orbit + eyeball + lacrimal gland + nasal cavity.

What does the posterior communicating artery connect?

ICA ↔ PCA.

What does the anterior choroidal artery mainly supply?

Choroid plexus of lateral + 3rd ventricles.

What are the terminal branches of the ICA?

ACA + MCA.

Where is the Circle of Willis located?

Base of brain.

What is the main purpose of the Circle of Willis?

Provides collateral arterial circulation.

Which 2 arterial systems are connected by the Circle of Willis?

Internal carotid + vertebrobasilar systems.

What arteries form the Circle of Willis?

• Right + left ACA

• Anterior communicating artery

• Terminal ICAs

• Right + left posterior communicating arteries

• Right + left PCA

What does the anterior communicating artery connect?

Right ↔ left ACA.

What does each posterior communicating artery connect?

ICA ↔ PCA.

Is the MCA part of the Circle of Willis?

No.

Where does the ACA originate?

Terminal branch of ICA.

What is the general course of the ACA?

Runs medially → around/along corpus callosum → medial cerebral hemisphere.

What does the ACA mainly supply?

Medial frontal + parietal lobes.

Which parts of the motor/sensory cortex are supplied by ACA?

Mainly lower-limb areas.

What other important areas does ACA supply?

Cingulate gyrus + precuneus.

Where does the MCA originate?

Terminal branch of ICA.

What is the general course of the MCA?

Laterally into lateral/Sylvian fissure → lateral hemisphere.

Which cerebral artery supplies the largest cortical territory?

MCA.

What does the MCA mainly supply?

Lateral frontal + parietal + temporal cortex.

Which motor/sensory areas are mainly supplied by MCA?

Face + upper limb.

What deep structures receive branches from the MCA?

Basal ganglia + internal capsule.

Where does the PCA originate?

Terminal branch of basilar artery.

What does the PCA mainly supply?

Occipital + inferomedial temporal lobes.

What major functional cortex does the PCA supply?

Visual cortex.

What important medial temporal structure is supplied by PCA?

Parahippocampal gyrus.

What are central cerebral arteries?

Small penetrating arteries supplying deep brain structures.

What do central arteries mainly supply?

Basal ganglia + internal capsule + thalamus/hypothalamus.

What are the anterolateral central arteries commonly called?

Perforating arteries.

What important structures do anterolateral central arteries supply?

Putamen + globus pallidus + caudate head + anterior internal capsule.

Basilar artery terminates as what?

PCA ×2.

ICA terminates as what?

ACA + MCA.