The arterial tree begins from the aorta. After the aorta leaves the heart, it divides into the ascending
aorta, the aortic arch, and the descending aorta.
The branches of the arch of aorta can be remembered as ABCS:
- A = Arch of Aorta
- B = Brachiocephalic artery
- C = Left common carotid artery
- S = Left subclavian artery
The Brachiocephalic artery divides into the right common carotid artery and the right subclavian artery. The common carotid arteries that is responsible for supplying blood to the head and neck, course upward in the neck along the lateral sides of the trachea and gives off 2 terminal branches: the internal and external carotid arteries at the level of upper border of thyroid cartilage (at the vertebral level of C4).
Course and Relations of External Carotid Artery (ECA):
The External carotid artery or carotis externa lies first deep to the anterior border of the sternocleidomastoid and then quite superficially in the anterior triangle of the neck, where its pulsations are usually visible as well as palpable. At first it is slightly deep to the internal carotid, then passes anterior and lateral to it. The internal jugular vein is first lateral to the external carotid then posterior to it, coming into lateral relationship to the internal carotid. The pharynx lies medially.
The external carotid artery ascends beneath the XII nerve and the posterior belly of the digastric to enter the parotid gland, within which it lies deep to the facial nerve and the retromandibular vein.
The artery ends within the parotid gland at the level of the neck of the mandible by dividing into the superficial temporal and internal maxillary arteries.
In summary, ECA after origin from the common carotid artery takes a slightly curved course upwards and anteriorly before inclining backwards to the space behind the neck of the mandible.Within the parotid gland, it branches terminally into the superficial temporal and maxillary arteries. Along its course, it rapidly diminishes in size and as it does so, gives of various branches.
Branches of External Carotid Artery (ECA):
The names of these branches are determined by the areas or structures they serve.
- Superior thyroid: muscles of hyoid region, larynx and vocal folds, and thyroid gland
- Lingual: tongue, muscles of the tongue, and salivary glands below the tongue
- Facial: pharynx, palate, chin, lips, and nose
- Ascending Pharyngeal: pharyngeal area and various lymph nodes
- Occipital: scalp on the back of the skull and various muscles in the neck
- Posterior auricular: ear and scalp over ear
- Maxillary: teeth and gums, the muscles of mastication, the nasal cavity, the eyelids, and the meninges
- Superficial temporal: temporal fascia and muscle, parotid gland
Clinical aspects of External Carotid Artery (ECA):
1. The 2 main vessels supplying the meninges are the meningeal branches of the occipital and maxillary arteries. Vasodilation of these vessels creates excessive pressure on the sensory receptors within the meninges, resulting in a headache.
2. Superficial temporal artery is palpable on the zygomatic process.
3. Middle meningeal artery which is the branch of Maxillary artery ascends through the foramen spinosum and helps to supply the meninges. Its practical importance is that it may be torn in a skull fracture and result in the formation of an extradural haematoma.
4. External carotid artery stenosis may follow carotid endarterectomy
How to remember the branches of External carotid artery?
Watch this video from Medchrome to remember the branches of External carotid artery:
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