Where is the carotid triangle?

The so-called carotid artery refers to the artery in the human neck, which is one of the most important arteries in the human body. In life, the human carotid artery will have many diseases, such as carotid artery sclerosis, and there are also very serious carotid artery aneurysms. These diseases will greatly affect the patient's health and even cause other complications. Many people don’t know where the carotid triangle is. Let’s take a closer look below.

Where is the carotid triangle?

The carotid triangle is located in front of the upper part of the sternocleidomastoid muscle. The anterior superior boundary is the posterior belly of the digastric muscle, the anterior inferior boundary is the superior belly of the omohyoid muscle, the tendon is bounded by the sternocleidomastoid muscle, and the superficial layer of the deep cervical fascia forms the top of the triangle.

There are the internal jugular vein and its branches, the common carotid artery and its branches, the hypoglossal nerve and its descending branches, branches, accessory nerve, and some deep cervical lymph nodes.

vein

The internal jugular vein is located lateral to the common carotid artery and is mostly covered by the sternocleidomastoid muscle. Its tributaries from top to bottom are the facial vein, lingual vein, and superior and middle thyroid veins. The lymph node located at the angle where the facial vein joins the internal jugular vein is called the digastric internal jugular lymph node. It collects lymph from the root of the tongue and is also known as the main lingual lymph node.

artery

1) Common carotid artery: Located on the inner side of the internal jugular vein, it is divided into the internal carotid artery and the external carotid artery at the upper edge of the thyroid cartilage. The enlarged area at the end of the common carotid artery and the beginning of the internal carotid artery is the carotid sinus, which has pressure receptors on its wall; there is a carotid glomerulus behind the bifurcation of the common carotid artery, which is a chemoreceptor. Both regulate blood pressure and respiration.

2) External carotid artery: It originates from the common carotid artery at the same level as the upper edge of the thyroid cartilage, and ascends vertically to the anterior and medial side of the internal carotid artery. From the upper edge of the thyroid cartilage to the greater cornu of the hyoid bone, the superior thyroid artery, lingual artery and facial artery are given out in sequence; the occipital artery is given out toward the back and upward near the lower edge of the posterior belly of the digastric muscle; the ascending pharyngeal artery is given out from the inner side of the origin of the external carotid artery and runs upward.

3) Internal carotid artery: runs from the posterolateral side of the external carotid artery to its posterior side, through the deep surface of the posterior belly of the digastric muscle to the retromandibular fossa. This artery has no branches in the neck.

nerve

The last three pairs of cranial nerves pass through the carotid triangle.

1) Hypoglossal nerve: It enters the triangle through the deep surface of the posterior belly of the digastric muscle, crosses the superficial surface of the internal carotid artery and the external carotid artery, and sends out a descending branch, called the superior root of the carotid loop, which descends along the superficial surface of the common carotid artery and participates in the formation of the carotid loop; this trunk runs forward and upward, and enters the submandibular triangle through the deep surface of the posterior belly of the digastric muscle again.

2) Accessory nerve: It enters the posterior superior corner of the cervical triangle through the deep surface of the posterior belly of the digastric muscle, crosses the superficial surface of the internal jugular vein, runs posteriorly and outwards, and sends muscle branches to the deep surface of the sternocleidomastoid muscle to innervate the muscle. The main trunk goes to the posterior cervical triangle.

3) Vagus nerve: It runs within the carotid sheath, located behind the internal carotid artery, common carotid artery and internal jugular vein. The branches within the carotid triangle include the superior laryngeal nerve and cardiac branches. The former is divided into internal and external branches between the inner side of the internal and external carotid arteries and the middle pharyngeal constrictor muscle; the internal branch bends forward and downward, penetrates the thyrohyoid membrane into the larynx, and controls the sensation of the laryngeal mucosa above the glottis; the external branch descends along the surface of the inferior pharyngeal constrictor muscle, innervating this muscle and the cricothyroid muscle. The cardiac branch descends along the surface of the common carotid artery into the thoracic cavity and participates in the formation of the cardiac plexus.

Digastric Shoulder Abdomen

It is the boundary between the carotid triangle and the submandibular triangle, and is also an important landmark for maxillofacial and neck surgery. Its superficial surface includes the greater auricular nerve, posterior mandibular vein and cervical branch of the facial nerve; its deep surface includes the internal carotid artery and vein, external carotid artery, vagus nerve, accessory nerve and hypoglossal nerve, as well as the cervical sympathetic trunk; the upper edge of the muscle includes the posterior auricular artery, facial nerve and glossopharyngeal nerve; the lower edge includes the occipital artery and hypoglossal nerve.