Major Arteries of the Head and Neck

Original Author: Oliver Jones
Last Updated: April 21, 2017
Revisions: 42

The head and neck receives the majority of its blood supply through the carotid and vertebral arteries. This article shall explore the anatomy of this arterial system – its anatomical course, branches, and clinical correlations.


Carotid Arteries

Fig 1.0 - Origin of the blood vessels of the upper limb. Note how the left common carotid and subclavian arteries arise directly from the arch of aorta.

Fig 1.0 – Origin of the blood vessels of the upper limb. Note how the left common carotid and subclavian arteries arise directly from the arch of aorta.

We shall start at the origin of the carotid arteries. The right common carotid artery arises from a bifurcation of the brachiocephalic trunk (the right subclavian artery is the other branch). This bifurcation occurs roughly at the level of the right sternoclavicular joint.

The left common carotid artery branches directly from the arch of aorta. The left and right common carotid arteries ascend up the neck, lateral to the trachea and the oesophagus. They do not give off any branches in the neck.

At the level of the superior margin of the thyroid cartilage (C4), the carotid arteries split into the external and internal carotid arteries. This bifurcation occurs in an anatomical area known as the carotid triangle.

The common carotid and internal carotid are slightly dilated here, this area is known as the carotid sinus, and is important in detecting and regulating blood pressure.

Fig 1.0 - Lateral vein of the neck, showing the origin and bifurcation of the common carotid artery.

Fig 1.1 – Lateral vein of the neck, showing the origin and bifurcation of the common carotid artery.

Clinical Relevance: Carotid Sinus Hypersensitivity

The carotid sinus is a dilated portion of the common carotid and internal carotid arteries. It contains specific sensory cells, called baroreceptors. The baroreceptors 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 people, the baroreceptors are hypersensitive to stretch. In these patients, external pressure on the carotid sinus can cause slowing of the heart rate and a decrease in blood pressure. The brain becomes underperfused, 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, called the carotid body. These act as peripheral chemoreceptors; detecting the O2 content of the blood, and relaying this information to the brain to regulate breathing rate.

External Carotid Artery

The external carotid artery supplies the areas of the head and neck external to the cranium. After arising from the common carotid artery, it travels up the neck,  posterior to the mandibular neck and anterior to the lobule of the ear. The artery ends within the parotid gland, by dividing into the superficial temporal artery and the maxillary artery. Before terminating, the external carotid artery gives off six branches:

  • Superior thyroid artery
  • Lingual artery
  • Facial artery
  • Ascending pharyngeal artery
  • Occipital artery
  • Posterior auricular artery

The facial, maxillary and superficial temporal arteries are the major branches of note. The maxillary artery supplies the deep structures of the face, while the facial and superficial temporal arteries generally supply superficial areas of the face.

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:

  1. 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.
  2. The numerous anastomoses formed by the arteries produce a very densely vascularised area.
  3. 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.

Fig 1.2 - Blood supply to the superficial structures of the face. Note the maxillary artery before it dissapears into the pterygopalatine fossa

Fig 1.2 – 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.

Fig 1.3 - 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.

Fig 1.3 – 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.

Internal Carotid Artery

The internal carotid arteries do not supply any structures in the neck, entering the cranial cavity via the carotid canal in the petrous part of the temporal bone. Within the cranial cavity, the internal carotid artery supplies:

  • The brain
  • Eyes
  • Forehead

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 more susceptible than the others.

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.

Vertebral Arteries

Fig 1.5 - Blood supply to the brain via the vertebral arteries

Fig 1.4 – Blood supply to the brain via the vertebral arteries

The right and left vertebral arteries arise from the subclavian arteries, medial to the anterior scalene muscle. They then ascend up the posterior side of the neck, through holes in the transverse processes of the cervical vertebrae, known as foramen transversarium.

The vertebral arteries enter the cranial cavity via the foramen magnum, and converge. They then give rise to the basilar arteries, which supply the brain. The vertebral arteries supply no branches to the neck, or extra-cranial structures.


Other Arteries of the Neck

The neck is supplied by arteries other than the carotids. The right and left subclavian arteries give rise to the thyrocervical trunk. From this trunk, several vessels arise, which go on to supply the neck.

  • The first branch of the thyrocervical trunk is the inferior thyroid artery. It supplies the thyroid gland
  • The ascending cervical artery arises from the inferior thyroid artery, as it turns medially in the neck. This vessel supplies the posterior prevertebral muscles.
  • The transverse cervical artery is the next branch off the thyrocervical trunk. It crosses the base of the carotid triangle, and supplies the trapezius and rhomboid muscles.
  • Lastly, the suprascapular artery arises. It supplies the posterior shoulder area.

 

Fig 1.5 - Lateral view of the neck, showing the thyrocervical trunk

Fig 1.5 – Lateral view of the neck, showing the thyrocervical trunk

 

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Question 1 / 6
From which artery does the left common carotid artery arise?

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Question 2 / 6
Which of the following factors explains the extensive bleeding of scalp laceration?

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Question 3 / 6
At which vertebral level do the common carotids bifurcate?

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Question 4 / 6
Which of the following is a branch of the external carotid artery?

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Question 5 / 6
Damage to which artery at the pterion causes an extradural haematoma?

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Question 6 / 6
Which artery gives off the vertebral artery?

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