The arterial blood supply to the neck, face and scalp arise from the branches of the arch of aorta.

The first branch from the aorta is brachiocephalic artery which forms right common carotid artery and right subclavian, then left common carotid branches which comes directly from the aorta and lastly the left subclavian artery.

The common carotid arteries are the main vessels supplying the head and neck region. Each divides into external carotid and internal carotid arteries.

Each external carotid artery branches gives several branches which supply structures of neck and face.

It is also supplied by branches of the maxillary and ophthalmic arteries.

The back of the scalp is supplied by the posterior auricular and occipital arteries.

There are numerous anastomoses between the branches.

The facial artery arises in the neck from the external carotid artery.

It passes onto the face at the anteroinferior border of masseter (where its pulse can be felt as it crosses the mandible).

The facial artery sends branches to the upper and lower lips (superior and inferior labial arteries) and to the side of the nose (lateral nasal artery) and then terminates as the angular artery, which supplies the medial angle of the eye.

This is the smaller terminal branch of the external carotid artery.

It arises in the parotid gland behind the neck of the mandible, where it is crossed by temporal and zygomatic branches of the facial nerve.

Initially deep, it becomes superficial as it passes over the posterior root of the zygomatic process of the temporal bone.

The superficial temporal artery supplies skin and muscles at the side of the face and in the scalp, the parotid gland and the temporomandibular joint.

Its named branches are the transverse facial, auricular, zygomatico-orbital, middle temporal, frontal and parietal arteries.

The middle temporal artery arises just above the zygomatic arch and perforates the temporal fascia to supply temporalis.

It anastomoses with the deep temporal branches of the maxillary artery.

Frontal (anterior) branch passes upwards towards the frontal tuberosity and supplies adjacent muscles, skin and pericranium in this region.

It anastomoses with its fellow of the opposite side and with the supraorbital and supratrochlear branches of the ophthalmic artery.

The parietal branch is larger than the frontal branch of the superficial temporal artery, and curves upwards and backwards.

It remains superficial to the temporal fascia, and anastomoses with its fellow of the opposite side and with the posterior auricular and occipital arteries.

The maxillary artery is the larger of the two terminal branches of the external carotid artery, and has three branches that supply the face, namely the mental, buccal and infraorbital arteries.

The mental artery arises from the first part of the maxillary artery as a terminal branch of the inferior alveolar artery.

It emerges onto the face from the mandibular canal at the mental foramen, and supplies muscles and skin in the chin region.

The mental artery anastomoses with the inferior labial and submental arteries.

The occipital artery arises in the neck from the external carotid artery, and enters the back of the scalp by piercing the investing layer of deep cervical fascia connecting the cranial attachments of trapezius and sternocleidomastoid.

The posterior auricular artery arises in the neck from the external carotid artery, ascends between the auricle and mastoid process and gives off an auricular branch supplying the cranial surface of the auricle and an occipital branch to supply the occipital belly of occipitofrontalis and the scalp behind and above the auricle.

The posterior auricular artery anastomoses with the occipital artery.

The venous blood from the head and neck is returned by deep and superficial veins.

Superficial veins with the same names as the branches of the external carotid artery returns venous blood from the superficial structure of the face and scalp unite to form the external jugular vein.

The facial vein which begins at the medial angle of the eye as the angular vein is the primary venous drainage of the face.

Inferior to the margin of the mandible, the facial vein is joined by the anterior branch of the retromandibular vein

It joins with maxillary vein to form the retro mandibular vein which divides into posterior and anterior branches.

The posterior auricular vein drains into the posterior retromandibular vein to form the external jugular vein.

The anterior branch of retromandibular vein joins with facial vein and drains directly or indirectly into the internal jugular vein.

The anterior jugular vein which drain the neck may also communicate with facial vein and drains into subclavian vein.

The external jugular drains into subclavian vein at the root of the neck.

The brain receives its arterial supply from two pairs of vessels, the vertebral and internal carotid arteries which are interconnected in the cranial cavity to produce an arterial circle (of Willis).

The two internal carotid arteries arise as one of the two terminal branches of the common carotid arteries.

They proceed superiorly to the base of the skull where they enter the carotid canal on either side.

Entering the cranial cavity each internal carotid artery gives off the ophthalmic artery, the posterior communicating artery, the middle cerebral artery, and the anterior cerebral artery.

The major branches that arise from the internal carotid artery; the anterior and middle cerebral arteries, form the anterior circulation that supplies the forebrain.

Each gives rise to branches that supply the cortex and branches that penetrate the basal surface of the brain, supplying deep structures such as the basal ganglia, thalamus, and internal capsule.

Each vertebral artery arises from the first part of each subclavian artery in the lower part of the neck, and passes superiorly through the transverse foramina of the upper six cervical vertebrae.

On entering the cranial cavity through the foramen magnum each vertebral artery gives off a small meningeal branch.

Continuing forward, the vertebral artery gives rise to three additional branches before joining with its companion vessel to form the basilar artery.

One branch joins with its companion from the other side to form the single anterior spinal artery, which then descends in the anterior median fissure of the spinal cord.

A second branch is the posterior spinal artery, which passes posteriorly around the medulla then descends on the posterior surface of the spinal cord in the area of the attachment of the posterior roots-there are two posterior spinal arteries, one on each side.

Just before the two vertebral arteries join, each gives off a posterior inferior cerebellar artery.

The right and left vertebral arteries come together at the level of the pons on the ventral surface of the brainstem to form the midline basilar artery.

The basilar artery joins the blood supply from the internal carotids in an arterial ring at the base of the brain (in the vicinity of the hypothalamus and cerebral peduncles) called the circle of Willis.

The basilar artery travels in a rostral direction along the anterior aspect of the pons.

Its branches in a caudal to rostral direction include the anterior inferior cerebellar arteries, several small pontine arteries, and the superior cerebellar arteries.

The basilar artery ends as a bifurcation, giving rise to two posterior cerebral arteries.

The cerebral arterial circle (of Willis) is formed at the base of the brain by the interconnecting vertebrobasilar and internal carotid systems of vessels.

This anastomotic interconnection is accomplished by

An anterior communicating artery connecting the left and right anterior cerebral arteries to each other.

Two posterior communicating arteries, one on each side, connecting the internal carotid artery with the posterior cerebral artery

Conjoining the two major sources of cerebral vascular supply via the circle of Willis presumably improves the chances of any region of the brain continuing to receive blood if one of the major arteries becomes occluded.

The posterior circulation of the brain supplies the posterior cortex, the midbrain, and the brainstem; it comprises arterial branches arising from the posterior cerebral, basilar, and vertebral arteries.

The physiological demands served by the blood supply of the brain are particularly significant because neurons are more sensitive to oxygen deprivation than other kinds of cells with lower rates of metabolism.

Venous drainage of the brain begins internally as networks of small venous channels lead to larger cerebral veins, cerebellar veins, and veins draining the brainstem, which eventually empty into dural venous sinuses.

The dural venous sinuses are endothelial-lined spaces between the outer periosteal and the inner meningeal layers of the dura mater, and eventually lead to the internal jugular veins

Emptying into the dural venous sinuses are diploic veins, which run between the internal and external tables of compact bone in the roof of the cranial cavity, and emissary veins, which pass from outside the cranial cavity to the dural venous sinuses.

The emissary veins are important clinically because they can be a conduit through which infections can enter the cranial cavity because they have no valves.

The dural venous sinuses include the superior sagittal, inferior sagittal, straight, transverse, sigmoid, and occipital sinuses, the confluence of sinuses, and the cavernous, sphenoparietal, superior petrosal, inferior petrosal and basilar sinuses.

The cavernous sinus is located bilaterally on each side of the sella turcica on the body of the sphenoid bone.

The cavernous sinus consists of a venous plexus of extremely thin-walled veins.

The cavernous sinus receives blood from the superior and inferior ophthalmic veins, superficial middle cerebral vein, and sphenoparietal sinus.

The cavernous sinuses drain postero-inferiorly through the superior and inferior petrosal sinuses.

These connections provide pathways for infections to pass from extracranial sites into intracranial locations.

In addition, because structures pass through the cavernous sinuses and are located in the walls of these sinuses they are vulnerable to injury due to inflammation.