The trigeminal artery is an artery that supplies the

basilar artery The basilar artery (U.K.: ; U.S.: ) is one of the arteries that supplies the brain with oxygen-rich blood. The two vertebral arteries and the basilar artery are known as the vertebral basilar system, which supplies blood to the posterior part o ...

with blood during

human embryonic development Human embryonic development or human embryogenesis is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of d ...

.Simon J. Dimmick and Kenneth C. Faulder. "Normal Variants of the Cerebral Circulation at Multidetector CT Angiography". ''RadioGraphics'' (2009) 29: 1036. Normally, the trigeminal artery involutes after the formation of the

posterior communicating artery In human anatomy, the left and right posterior communicating arteries are small arteries at the base of the brain that form part of the circle of Willis. Anteriorly, it unites with the internal carotid artery (ICA) (prior to the terminal bifurcat ...

.Waleed Azab, Johnny Delashaw, and Mohammed Mohammed. "Persistent Primitive Trigeminal Artery: A Review." ''Turkish Neurosurgery'' (2012) 22:400. However, in some cases, the artery persists into adulthood and can cause medical complications, including

intracranial aneurysm An intracranial aneurysm, also known as a cerebral aneurysm, is a cerebrovascular disorder characterized by a localized dilation or ballooning of a blood vessel in the brain due to a weakness in the vessel wall. These aneurysms can occur in an ...

s.Stephan Meckel, Bjoern Spittau & William McAuliffe. "The persistent trigeminal artery: development, imaging anatomy, variants, and associated vascular pathologies." ''Neuroradiology'' (2013) 55:5–16.

Normal development

The trigeminal artery arises from the primitive

internal carotid artery The internal carotid artery is an artery in the neck which supplies the anterior cerebral artery, anterior and middle cerebral artery, middle cerebral circulation. In human anatomy, the internal and external carotid artery, external carotid ari ...

during development, when the embryo is approximately 6 weeks old. The trigeminal artery then

anastomoses An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf#Veins, leaf veins, or streams. Such a connection may be ...

with the

. At this point in development, the trigeminal artery serves as the main blood supply for the hindbrain, as other vessels in the region have yet to mature.William S. Fields. "The significance of persistent trigeminal artery: Carotid-basilar anastomosis. ''Radiology'' (1968) 91: 1096-1101. As the internal carotid artery branches more

caudally Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

to form the

, the trigeminal artery becomes less important in supplying blood and ultimately involutes. The time period from the initial development of the artery to its ultimate involution is only 7 to 10 days; if the artery has not involuted at the end of this period it persists into adulthood.Ljiljana Vasovic, et al. "Trigeminal artery: a review of normal and pathological features." ''Child's Nervous System'' (2012) 28: 33-46.

Persistent trigeminal artery

In around 0.1 to 0.6% of individuals, as sampled by

magnetic resonance angiography Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate ...

, the trigeminal artery fails to involute and remains in the adult brain, in a condition called persistent trigeminal artery. This condition is more common in women than in men, with approximately 1.8 times as many women having the condition.Eri O'uchi and Toshihiro O'uchi. "Persistent primitive trigeminal arteries (PTA) and its variant (PTAV): analysis of 103 cases detected in 16,415 cases of MRA over 3 years. ''Interventional Neuroradiology'' (2010) 52:1111-1119. Knowledge of a persistent trigeminal artery may be important in certain brain surgeries, as the condition is rare and an accidental cut to the artery could lead to

hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, ...

. Although the discovery of a persistent trigeminal artery is sometimes an incidental finding, its presence is also associated with various pathological conditions, and must therefore be considered carefully when diagnosing these conditions.Alejandro M. Russo and Maria C. Sienra. "Persistent trigeminal artery: case report". ''International Journal of Anatomical Variations'' (2011) 4: 157-160. There are 3 types of persistent trigeminal artery (PTA): Saltzman Type 1: PTA supplies the distal vertebrobasilar arteries. In this instance, the posterior communicating artery and the caudal basilar artery is either absent or hypoplastic. There are also hypoplastic distal vertebral arteries. Saltzman Type 2: The PTA supplies the superior cerebellar artery while the posterior cerebral artery is supplied by the posterior communicating artery Saltzman Type 3: The PTA does not join the basilar artery but rather terminates as the superior cerebellar artery (type 3A); Anterior inferior cerebellar artery (3B) and posterior inferior cerebellar artery (3C)

Associated conditions

A persistent trigeminal artery is associated with an increased risk of aneurysm, though some studies have suggested that this finding may be an effect of

selection bias Selection bias is the bias introduced by the selection of individuals, groups, or data for analysis in such a way that proper randomization is not achieved, thereby failing to ensure that the sample obtained is representative of the population inte ...

, as most individuals do not undergo the tests necessary to identify the condition. Persistent trigeminal artery has been identified as a rare cause of

trigeminal neuralgia Trigeminal neuralgia (TN or TGN), also called Fothergill disease, tic douloureux, trifacial neuralgia, is a chronic pain, long-term pain disorder that affects the trigeminal nerve, the nerve responsible for sensation in the face and motor funct ...

, with 2.2% prevalence of persistent trigeminal artery among trigeminal neuralgia patients.Licia Pereira, et al. "Persistent trigeminal artery: Angio-tomography and angio-magnetic resonance finding". ''Arquivos de Neuro-Psiquiatria'' (2009) 67:882-885. Surgery to move the persistent trigeminal artery away from the trigeminal nerve has been successful in treating the trigeminal neuralgia in some cases.Chang Kyu Park, et al. "Trigeminal neuralgia caused by persistent primitive trigeminal artery." ''Journal of Korean Neurosurgery Society'' (2014) 56: 278-280. In some cases, presence of a persistent trigeminal artery concurs with

hypoplasia Hypoplasia (; adjective form ''hypoplastic'') is underdevelopment or incomplete development of a tissue or organ.basilar artery The basilar artery (U.K.: ; U.S.: ) is one of the arteries that supplies the brain with oxygen-rich blood. The two vertebral arteries and the basilar artery are known as the vertebral basilar system, which supplies blood to the posterior part o ...

, in which case the

is responsible for most blood flow to the upper

pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other mammals, lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of ...

cerebellum The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or eve ...

midbrain The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum. It is functionally associated with vision, hearing, mo ...

, and parts of the temporal and

occipital lobes The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin , 'behind', and , 'head'. The occipital lobe is the visual processing ...

, meaning that anything disrupting blood flow in the internal carotid artery could lead to

ischemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems ...

in these regions.Gabriel Alcalá-Cerra, R Shane Tubbs, and Lucía M Niño-Hernández. "Anatomical features and clinical relevance of a persistent trigeminal artery". ''Surgical Neurology International'' (2012) 3:111. In addition, persistent trigeminal artery has been associated with

vertebrobasilar insufficiency Vertebrobasilar insufficiency (VBI) describes a temporary set of symptoms due to decreased blood flow (ischemia) in the Posterior (anatomy), posterior circulation of the brain. The posterior circulation supplies the medulla oblongata, medulla, p ...

, brainstem

, and carotid cavernous fistulae.

References

{{Reflist Arteries of the head and neck