Vertebral artery

Vertebral artery
The branches of the subclavian artery and the course of the vertebral artery in the neck (schematic).
The three major arteries of the cerebellum: the SCA, AICA, and PICA. (Vertebrals labeled at bottom.)
Details
Source	subclavian arteries
Branches	Meningeal branches Posterior spinal Anterior spinal PICA Basilar artery
Vein	vertebral vein
Identifiers
Latin	arteria vertebralis
MeSH	A07.231.114.839
Dorlands /Elsevier	a_61/12156505
TA	A12.2.08.002
FMA	3956
Anatomical terminology [edit on Wikidata]

The vertebral arteries are major arteries of the neck. They branch from the subclavian arteries and merge to form the single midline basilar artery in a complex called the vertebrobasilar system, which supplies blood to the posterior part of the circle of Willis and thus significant portions of the brain.

Course

Arteries of the neck. The vertebral arteries arise from the subclavian arteries and join to form the basilar artery

The vertebral arteries arise from the subclavian arteries, one on each side of the body, then enter deep to the transverse process at the level of the 6th cervical vertebrae (C6), or occasionally (in 7.5% of cases) at the level of C7. They then proceed superiorly, in the transverse foramen (foramen transversarium) of each cervical vertebra. Once they have passed through the transverse foramen of C1 (also known as the atlas), the vertebral arteries travel across the posterior arch of C1 and through the suboccipital triangle before entering the foramen magnum.

Nunziante Ippolito, a Neapolitan physician, identified the "angle of Nunziante Ippolito" to find the vertebral artery, between the anterior scalene muscle and the longus colli muscle.^[1]

Inside the skull, the two vertebral arteries join to form the basilar artery at the base of the Pons. The basilar artery is the main blood supply to the brainstem and connects to the Circle of Willis to potentially supply the rest of the brain if there is compromise to one of the carotids. At each cervical level, the vertebral artery sends branches to the surrounding musculature via the anterior spinal arteries.

The branches of the subclavian artery are:

1. Vertebral;
2. Internal mammary;
3. Thyrocervical;
4. Costocervical;
5. Descending or Dorsal scapular artery (50% of the time).

Division into four parts

Segments

The vertebral artery may be divided into four parts:

First part

The first part runs upward and backward between the Longus colli and the Scalenus anterior.

In front of it are the internal jugular and vertebral veins, and it is crossed by the inferior thyroid artery; the left vertebral is crossed by the thoracic duct also.

Behind it are the transverse process of the seventh cervical vertebra, the sympathetic trunk and its inferior cervical ganglion

Second part

The second part runs upward through the foramina in the transverse processes of the C6 to C2 vertebræ, and is surrounded by branches from the inferior cervical sympathetic ganglion and by a plexus of veins which unite to form the vertebral vein at the lower part of the neck.

It is situated in front of the trunks of the cervical nerves, and pursues an almost vertical course as far as the transverse process of the axis.

Third part

The third part issues from the C2 foramen transversarium on the medial side of the Rectus capitis lateralis. It is further subdivided into the vertical part V3v passing vertically upwards, crossing the C2 root and entering the foramen transversarium of C1, and the horizontal part V3h, curving medially and posteriorly behind the superior articular process of the atlas, the anterior ramus of the first cervical nerve being on its medial side; it then lies in the groove on the upper surface of the posterior arch of the atlas, and enters the vertebral canal by passing beneath the posterior atlantoöccipital membrane.

This part of the artery is covered by the Semispinalis capitis and is contained in the suboccipital triangle—a triangular space bounded by the Rectus capitis posterior major, the Obliquus superior, and the Obliquus inferior.

The first cervical or suboccipital nerve lies between the artery and the posterior arch of the atlas.

Fourth part

The fourth part pierces the dura mater and inclines medialward to the front of the medulla oblongata; it is placed between the hypoglossal nerve and the anterior root of the first cervical nerve and beneath the first digitation of the ligamentum denticulatum.

At the lower border of the pons it unites with the vessel of the opposite side to form the basilar artery.

Variations

The left vertebral artery is usually larger and carries more blood.^[2] In 3-15% of the population, a bony bridge called the arcuate foramen covers the groove for the vertebral artery on vertebra C1.

References

Additional images

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  Section of the neck at about the level of the sixth cervical vertebra.

• 

  The arteries of the base of the brain.

• 

  The arteries of the base of the brain.

• 

  Diagram of the arterial circulation at the base of the brain.

• 

  Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.

• 

  Posterior primary divisions of the upper three cervical nerves.

• 

  Lateral view

• 

  Relationship of the vertebral artery to the suboccipital muscles.

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  Vertebral artery

• 

  Vertebral artery

• 

  Spinal cord. Brachial plexus. Cerebrum. Inferior view. Deep dissection.

External links

Wikimedia Commons has media related to Vertebral artery.

• Anatomy photo:28:09-0201 at the SUNY Downstate Medical Center
• http://neuroangio.org/anatomy-and-variants/vertebral-artery/
• MedEd at Loyola Neuro/neurovasc/navigation/vert.htm
• Atlas image: n3a8p1 at the University of Michigan Health System
• lesson5 at The Anatomy Lesson by Wesley Norman (Georgetown University) (vertebralcolumnfromleftweb)
• Anatomy diagram: 13048.000-1 at Roche Lexicon - illustrated navigator, Elsevier
• Anatomy diagram: 13048.000-3 at Roche Lexicon - illustrated navigator, Elsevier