Overview: Arterial Supply to the Head & Neck

Clinical Relevance

Carotid Sinus Hypersensitivity

The carotid sinus is a dilated portion of the common carotid artery and proximal internal carotid artery. It contains specialised sensory cells known as baroreceptors. These cells detect stretch as a measure of blood pressure. The glossopharyngeal nerve feeds this information to the brain, and this is used to regulate blood pressure.

In some individuals, the baroreceptors are hypersensitive to stretch. External pressure on the carotid sinus can cause slowing of the heart rate and a decrease in blood pressure. The brain becomes under-perfused and syncope results. In such patients, checking the pulse at the carotid triangle is not advised.

External to the carotid sinus, there is a cluster of nervous cells known as the carotid body. These cells act as peripheral chemoreceptors; detecting the O2 content of the blood and relaying this information to the brain to regulate breathing rate.

Clinical Relevance

Blood Supply to the Scalp

The posterior auricular, occipital and superficial temporal arteries (along with two branches of the internal carotid artery; supra-orbital and supratrochlear) combine to provide a dense blood supply to the scalp. Injuries to the scalp can cause excessive bleeding for various reasons:

• The walls of the arteries are tightly and closely bound to the underlying connective tissue of the scalp. This prevents them from constricting to limit blood loss following injury or laceration.
• The numerous anastomoses formed by the arteries produce a very densely vascularised area.
• Deep lacerations can involve the epicranial aponeurosis, which is worsened by the opposing pulls of the occipital and frontalis muscles.

Despite the possible heavy bleeding, it is important to note that the bony skull gets its blood from an alternative source (middle meningeal artery), and so will not undergo avascular necrosis.

By TeachMeSeries Ltd (2026)

Fig 3
Blood supply to the superficial structures of the face. Note the maxillary artery before it disappears into the pterygopalatine fossa, to supply the deep structures of the face.

Clinical Relevance

Extradural Haematoma

The middle meningeal artery is a branch of the maxillary artery. It is unique as it supplies some intracranial structures (remember, the external carotid artery and its branches usually supply extra-cranial structures).

The middle meningeal artery supplies the skull and the dura mater (the outer membranous layer covering the brain). A fracture of the skull at its weakest point, the pterion, can injure or completely lacerate the MMA. Blood will then collect in between the dura mater and the skull, causing a dangerous increase in intra-cranial pressure. This is known as an extradural haematoma.

The increase in intra-cranial pressure causes a variety of symptoms: nausea, vomiting, seizures, bradycardia and limb weakness. It is treated by diuretics in minor cases, and drilling burr holes into the skull the more extreme haemorrhages.

By TeachMeSeries Ltd (2026)

Fig 4
Lateral view of the skull, showing the path of the meningeal arteries. Note the pterion, a weak point of the skull, where the anterior middle meningeal artery is at risk of damage.

Clinical Relevance

Atherosclerosis of the Carotid Arteries

The swelling at the bifurcation of the common carotid arteries, the carotid sinus, produces turbulent blood flow. This increases the risk of atheroma formation in this area, with the internal carotid most susceptible.

Atherosclerotic thickening of the tunica intima of these arteries will reduce blood flow to the brain, resulting in the variety of neurological symptoms; headache, dizziness, muscular weakness. If blood flow is completely occluded, a cerebral ischaemia (stroke) results.

If atherosclerosis of the carotid arteries is suspected, a Doppler study can be used to assess the severity of any thickening. In severe cases, the artery can be opened, and the atheromatous tunica intima removed. This procedure is called a carotid endarterectomy.