Triangles of the Neck
Original Editor - Carina Therese Magtibay
Top Contributors - Carina Therese Magtibay, Ewa Jaraczewska and Kim Jackson
Description[edit | edit source]
The neck is the anatomical region that supports the head and serves as a conduit for vital structures passing to and from the torso. As a geometric region, it can be clinically divided using anatomical triangles.
The sternocleidomastoid muscle obliquely crosses the neck to form the division between the two major neck triangles: anterior triangle and posterior triangle. Both triangles are further divided into sub-triangles. [2][3]
- Anterior Triangle
- Digastric/Submandibular Triangle
- Carotid Triangle
- Muscular Triangle
- Submental Triangle
- Posterior Triangle
- Occipital Triangle
- Subclavian/Supraclavicular
The neck is limited[2]:
- superiorly by the inferior border of the mandible
- anteriorly by the midline of the neck
- inferiorly by the superior border of the clavicle
- posteriorly by the anterior margin of the trapezius muscle.
Anterior Triangle[edit | edit source]
- Superior border - inferior border of the mandible
- Medial border- midline of the neck
- Lateral border- anterior border of the sternocleidomastoid muscle
The Anterior Triangle has an apex extending to the sternum's manubrium. It is made up of three paired triangles: submandibular (digastric), carotid, and muscular (omotracheal/infrahyoid) triangles, and one unpaired triangle: submental triangle.
Submandibular/Digastric Triangle[edit | edit source]
- Superior - inferior border of the mandible
- Anterior - anterior belly of digastric muscle
- Posterior - the posterior belly of the digastric muscle
- Inferior - hyoid bone
Floor: mylohyoid muscle
Contents:[2]
- Glands and lymphatics: submandibular gland and lymph nodes, lower pole of the parotid gland.
- Blood vessels: facial, lingual and submental arteries and veins
- Nerves: marginal mandibular branch of the facial nerve, nerve to the mylohyoid, hypoglossal nerve (CN XII)
Clinical Significance:[6]
- Neoplasms, infectious and immunologic pathologies can arise from the submandibular triangle.
- Sialadenitis- inflammation of the submandibular salivary gland. The most common pathology seen in the submandibular triangle.
- Pleomorphic adenoma- the most common benign neoplasm arising in the submandibular triangle followed by adenolymphoma, also known as Warthin’s tumour
- Adenoid cystic carcinoma- the most common malignant neoplasm in the submandibular triangle, followed by mucoepidermoid carcinoma.
Carotid Triangle[edit | edit source]
Borders:[2]
- Superior - stylohyoid and posterior belly of digastric muscles
- Anterior - the superior belly of the omohyoid muscle
- Posterior - anterior border of the sternocleidomastoid muscle
Floor: hyoglossus, thyrohyoid, and inferior and middle pharyngeal constrictor muscles
Contents:[2]
- Arteries: common carotid and its bifurcation into internal and external carotid arteries, superior thyroid, lingual, facial, occipital, and ascending pharyngeal arteries
- Veins: internal jugular, superior thyroid, lingual, facial, ascending pharyngeal, and occipital veins
- Nerves: external and internal branches of the superior laryngeal nerve arising from the vagus nerve (CN X), hypoglossal nerve (CN XII).
Clinical Significance:[5]
- Distention of the jugular vein can be palpated and assessed in the carotid triangle
- Internal jugular vein is usually utilized to establish central venous access for parental nutrition, dialysis, and administration of chemotherapy drugs.
- Carotid sinus is a baroreceptor that regulates blood pressure. Carotid sinus massage can be performed to terminate supraventricular tachycardia and other cardiac arrhythmias as.
Muscular Triangle[edit | edit source]
- Anterior- midline of the neck
- Inferoposterior- anterior margin of the sternocleidomastoid muscle
- Posterosuperior- the superior belly of the omohyoid muscle
Contents:[2]
- Blood vessels: superior thyroid artery, anterior jugular and inferior thyroid veins
- Lymphatics: anterior cervical, infrahyoid, prelaryngeal, thyroid, pretracheal, paratracheal lymph nodes
- Muscles: thyrohyoid, sternothyroid, sternohyoid, omohyoid muscles
- Nerves: ansa cervicalis (C1-3)
- Organs: esophagus, trachea, thyroid gland, and the lower part of the larynx
Clinical Significance:[2]
- Tracheostomy and thyroidectomy- surgically accessed through the muscular triangle
- Injury of the superior thyroid artery can result in bleeding during surgery.
Submental Triangle[edit | edit source]
Borders:[2]
- Inferior - hyoid bone
- Lateral - the anterior belly of the digastric muscle
- Medial - midline of the neck
Floor: mylohyoid muscle
Contents:[2]
- submental lymph nodes
- anterior jugular vein
Clinical Significance:[8]
- Tumors and cysts develop within the submental triangle
- Abscess from odontogenic infections can spread into the submental space
- Swollen submental lymph nodes can be indicative of malignant lesions. However, lesions in this area commonly develop from a local and benign pathology of the head and neck
- The submental lymph nodes are commonly involved in the metastasis of oral cavity cancer[9]
Posterior Triangle[edit | edit source]
Borders:[2]
- Anterior - posterior margin of sternocleidomastoid muscle
- Posterior - anterior margin of trapezius muscle
- Inferior - middle one-third of clavicle
Two subdivisions are formed within the posterior triangle: Occipital Triangle and the Subclavian/Supraclavicular Triangle
Occipital Triangle[edit | edit source]
Borders:[2]
- Anterior - posterior margin of sternocleidomastoid muscle
- Posterior - anterior margin of trapezius muscle
- Inferior - the inferior belly of the omohyoid muscle
Floor: levator scapulae, splenius capitis, and middle and posterior scalene muscles
Contents:[2]
- Artery: transverse cervical artery
- Lymphatics: accessory lymph nodes and inferior deep lateral cervical lymph nodes
- Nerves: accessory nerve (CN XI), cutaneous and muscular branches of the cervical plexus, the uppermost part of brachial plexus, supraclavicular nerves
Clinical Significance:
- A lot of nerves pass through the occipital triangle. It houses major nerves that innervate muscles vital for head and neck functions
Subclavian/Supraclavicular/Omoclavicular Triangle[edit | edit source]
Borders: [2]
- Superior - the inferior belly of the omohyoid muscle
- Anterior-posterior edge of the sternocleidomastoid muscle
- Inferior - clavicle
Contents: [2]
- Blood vessels: subclavian artery and vein
- Nerves: brachial plexus trunks and nerve to subclavius muscle
- Lymphatics: supraclavicular lymph nodes
Clinical Significance:[11]
- Virchow’s node, the left-sided supraclavicular lymph node, can be used to aid in the discovery and diagnosis of carcinomas originating from the abdomen. Troisier’s sign (an enlarged, firm, non-tender Virchow’s node) can indicate cancer arising from the stomach, ovaries, testicles, and kidneys.
- The right-sided supraclavicular lymph node drains lymphatic fluid from the thorax. A firm, enlarged, non-tender right-sided supraclavicular lymph node can indicate metastasis from lung or oesophagal cancer and Hodgkin’s lymphoma.
References[edit | edit source]
- ↑ 5MinuteSchool. TRIANGLES OF THE NECK ANATOMY MADE EASY - EXPLAINED in 3 MINUTES!! CERVICAL TRIANGLES. Available from: https://www.youtube.com/watch?v=CUvmlf3Wxng [last accessed 05/11/2020]
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 Kikuta S, Iwanaga J, Kusukawa J, Tubbs RS. Triangles of the neck: a review with clinical/surgical applications. Anatomy & Cell Biology. 2019 Jun 1;52(2):120-7.
- ↑ Kohan EJ, Wirth GA. Anatomy of the neck. Clinics in plastic surgery. 2014 Jan 1;41(1):1-6.
- ↑ Anatomy Knowledge. The Anterior Triangle of the Neck - Boundaries x Subdivisions | Anatomy Tutorial. Available from: https://www.youtube.com/watch?v=YOgE2pmXfZg [last accessed 10/06/2020]
- ↑ 5.0 5.1 Stathakios J, Carron MA. Anatomy, Head and Neck, Neck Triangle. InStatPearls [Internet] 2021 Jul 31. StatPearls Publishing.
- ↑ 6.0 6.1 Casale J, Varacallo M. Anatomy, Head and Neck, Submandibular Triangle. In: StatPearls. StatPearls Publishing, Treasure Island (FL); 2022. PMID: 30521254.
- ↑ Standring S. Gray's anatomy: the anatomical basis of clinical practice. 41st ed. London: Elsevier Health Sciences; 2015.
- ↑ Al-Missri MZ, Al Khalili Y. Anatomy, Head and Neck, Submental Triangle. InStatPearls [Internet] 2022 Jun 4. StatPearls Publishing.
- ↑ Trivić A, Krejović-Trivić S, Milovanović J, Djukić V, Arsović N, Dimitrijević M, Petrović Z, Mikić A. Distribution of cervical metastases from carcinoma of the cervicofacial region. Acta Chirurgica Iugoslavica. 2004 Jan 1;51(1):83-7.
- ↑ Anatomy Knowledge. The Posterior Triangle of the Neck - Boundaries & Content - Head & Neck Anatomy. Available from: https://www.youtube.com/watch?v=UoVIk4tvX_w [last accessed 16/09/2019]
- ↑ Casale J, Geiger Z. Anatomy, Head and Neck, Posterior Neck Triangle. InStatPearls [Internet] 2021 Jul 26. StatPearls Publishing.