Main arterial trunks
The main blood supply to the neck is provided by branches of the common carotid artery (a. carotis communis). In the bifurcation area, it divides into two major vessels. An important reflexogenic structure, the carotid body (glomus caroticum), is also located here.
The internal carotid artery (a. carotis interna) has a characteristic topographic feature: along its course through the neck, right up to its entry into the cranial cavity, it typically gives off no branches.
The external carotid artery (a. carotis externa) is the main source of blood supply for the soft tissues and organs of the neck. Its major branches arise from the trunk within the borders of the carotid triangle and are traditionally divided into anterior, posterior, and medial groups.
Anterior group of branches of the external carotid artery
- Superior thyroid artery (a. thyroidea superior). Most commonly, it is the very first branch, although it may occasionally originate from the bifurcation or even the common carotid artery. Descending toward the upper pole of the thyroid gland, it forms an arch. It gives off a large superior laryngeal artery (a. laryngea superior), which pierces the thyrohyoid membrane together with the nerve of the same name.
- The lingual artery (a. lingualis). The second branch, arising at the level of the hyoid bone (sometimes by a common trunk with the facial artery). It runs deep to the m. hyoglossus, which separates it from the lingual vein. The artery branches within the body of the tongue, giving off dorsal branches of the tongue (rr. dorsales linguae) and the deep artery of the tongue (a. profunda linguae), and also supplies the tissues of the floor of the mouth and salivary glands via the sublingual artery (a. sublingualis).
- Facial artery (a. facialis). The third branch, originating in the region of the greater horn of the hyoid bone or the angle of the mandible. It passes deep to the posterior belly of the digastric muscle. In the neck, it gives off the ascending palatine artery (a. palatina ascendens), which passes between the styloglossus and stylopharyngeus muscles and supplies the palatine tonsil.
Posterior and medial branches
The following vessels arise from the posterior and medial semicircumferences of the a. carotis externa:
- The occipital artery (a. occipitalis). Arises at the same level as the facial artery. It runs posteriorly along the posterior belly of the digastric muscle, passes between the mastoid process and the external occipital protuberance, pierces the trapezius muscle, and branches superficially to the epicranial muscle. Its sternocleidomastoid branches form important anastomoses with the subclavian artery basin.
- The posterior auricular artery (a. auricularis posterior). Runs posterior to the auricle. It gives off the stylomastoid artery (a. stylomastoidea), which enters the stylomastoid foramen of the skull together with the facial nerve and supplies the tympanic cavity.
- The ascending pharyngeal artery (a. pharyngea ascendens). Arises from the posterior wall near the bifurcation. It ascends along the lateral wall of the pharynx medial to the stylopharyngeus muscle. It supplies the pharyngeal wall, deep neck muscles, dura mater, and the medial wall of the tympanic cavity.
Blood supply to the thyroid gland
The thyroid gland has a rich and complex vascular network represented by the superior and inferior thyroid artery systems.
The superior thyroid artery descends parallel and medial to the external branch of the superior laryngeal nerve. At a distance of 1.5–2.0 cm from the upper pole of the lateral lobe of the gland, it divides into branches, supplying the upper margin of the isthmus as well as the lateral, anterior, and posterior surfaces of the lateral lobe.
The inferior thyroid artery (a. thyroidea inferior) originates from the thyrocervical trunk. It ascends to the level of the sixth cervical vertebra (C6), forms a characteristic loop (arc), and descends to the lower third of the posterior surface of the gland. The ascending part of the artery runs beneath the prevertebral (fifth) fascia of the neck, located medially and parallel to the phrenic nerve (n. phrenicus). The branches of this artery at the posterior surface of the lateral lobe are in close syntopy with the recurrent laryngeal nerve (n. laryngeus recurrens), crossing it anteriorly or posteriorly.
Briefly: answers to topical questions
At what level does the bifurcation of the common carotid artery occur?
The bifurcation of the common carotid artery predominantly occurs at the level of the upper margin of the thyroid cartilage (approximately the level of the fourth cervical vertebra). Less commonly, the division of the artery occurs at other levels:
- Upper margin of the thyroid cartilage — in 54% of cases.
- Hyoid bone — in 29% of cases.
- Angle of the mandible — occurs rarely.
What structures form the boundaries of Pirogov's triangle?
The boundaries of Pirogov's triangle are formed by a nerve and the muscles of the neck. Within the submandibular triangle, the following landmarks are distinguished:
- Superiorly — hypoglossal nerve (n. hypoglossus, XII cranial nerve).
- Anteriorly — posterior border of the mylohyoid muscle (m. mylohyoideus).
- Inferiorly and posteriorly — tendon of the posterior belly of the digastric muscle (m. digastricus).
- Floor — hyoglossus muscle (m. hyoglossus), which separates the lingual vein and artery.
What branches does the facial artery give off in the neck before looping over the mandible?
Before looping over the mandible, the facial artery (a. facialis) gives off the following branches in the neck:
- Ascending palatine artery (a. palatina ascendens) — runs between the stylopharyngeus and styloglossus muscles, supplies the palatine tonsil.
- Submental artery (a. submentalis) — runs from the submandibular triangle into the submental region together with the vein of the same name.
How do the external and internal carotid arteries relate topographically within the carotid triangle?
In the carotid triangle, the external carotid artery is typically located medially and anteriorly relative to the internal carotid artery. Both arteries in the upper part of the neck lie internal (medial) to the sternocleidomastoid muscle (m. sternocleidomastoideus). At the same time, the internal carotid artery gives off no branches in the neck, whereas the external carotid artery gives off several branches (superior thyroid, lingual, facial, and others).
Which arteries participate in the blood supply to the thyroid gland?
The blood supply to the thyroid gland involves two pairs of arteries:
- Superior thyroid arteries (aa. thyroideae superiores dextra et sinistra) — branches of the external carotid arteries (a. carotis externa).
- Inferior thyroid arteries (aa. thyroideae inferiores dextra et sinistra) — branches of the thyrocervical trunks (truncus thyrocervicalis) of the subclavian arteries.
Class and exam questions
Does the internal carotid artery give off branches in the neck?
Normally, the internal carotid artery gives off no branches in the neck until it enters the cranial cavity.
At what level does the lingual artery branch off?
It arises from the external carotid artery at the level of the hyoid bone, occasionally forming a common trunk with the facial artery.
What is the clinical significance of Pirogov's triangle?
Within this triangle, ligation of the lingual artery is performed to reduce blood supply and prevent hemorrhage during operations on the tongue.
What else to study on this topic
- Syntopy of arteries with cranial nerves (cranial nerves IX, X, XI, XII)
- Topography of the thyrocervical trunk and its branches
- Anastomoses of the occipital artery with branches of the subclavian artery
- Pharyngeal nerve plexus and its vascular connections
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