The Vertibrobasilar System see Figure

A. The vertebral artery is a branch of the subclavian artery. It gives rise to the anterior spinal artery (see I) and the posterior inferior cerebellar artery (PICA), which supplies the dorsolateral quadrant of the medulla. This quadrant includes the nucleus am-biguus (CN IX, X, and XI) and the inferior surface of the cerebellum.

B. The basilar artery is formed by the two vertebral arteries. It gives rise to the following arteries.

1. The paramedian branches of the pontine arteries supply the base of the pons, which includes the corticospinal fibers and the exiting root fibers of the abducent nerve (CN VI).

2. The labyrinthine artery arises from the basilar artery in 15% of people. It arises from the anterior inferior cerebellar artery in 85% of people.

3. The anterior inferior cerebellar artery (AICA) supplies the caudal lateral pontine tegmentum, including CN VII, the spinal trigeminal tract of CN V, and the inferior surface of the cerebellum.

4. The superior cerebellar artery supplies the dorsolateral tegmentum of the rostral

Medial side

Posterior cerebral artery

Substantia nigra — Basis pedunculi

Anterior choroidal artery -

Middle Cerebral Artery Superior Branch

^-Globus pallidus

- Middle cerebral artery

Caudate nucleus _____Lateral ventricle

^ Penetrating branches of middle cerebral artery (lateral striate arteries)

- Internal capsule

Putamen

Figure 3-3. Coronal section through the cerebral hemisphere at the level of the internal capsule and thalamus showing the major vascular territories.

^-Globus pallidus

- Middle cerebral artery

Caudate nucleus _____Lateral ventricle

Posterior cerebral artery

^ Penetrating branches of middle cerebral artery (lateral striate arteries)

- Internal capsule

Putamen

Medial side

Anterior cerebral artery

Caudate nucleus Lateral ventricle Thalamus

Third ventricle N

Posterior cerebral artery

Substantia nigra — Basis pedunculi

Anterior choroidal artery -

Figure 3-3. Coronal section through the cerebral hemisphere at the level of the internal capsule and thalamus showing the major vascular territories.

pons (i.e., rostral to the motor nucleus of CN V), the superior cerebellar peduncle, the superior surface of the cerebellum and cerebellar nuclei, and the cochlear nuclei.

5. The posterior cerebral artery (see Figures 3-1, 3-2, and 3-3) is connected to the carotid artery through the posterior communicating artery. It provides the major blood supply to the midbrain. It also supplies the thalamus, lateral and medial geniculate bodies, and occipital lobe (which includes the visual cortex and the inferior surface of the temporal lobe, including the hippocampal formation). Occlusion of this artery results in a contralateral hemianopia with macular sparing.

IV. THE BLOOD SUPPLY OF THE INTERNAL CAPSULE comes primarily from the lateral striate arteries of the middle cerebral artery and the anterior choroidal artery.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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