Author: Lorenzo Crumbie MBBS, BSc•Reviewer: Uruj Zehra MBBS, MPhil, PhDLast reviewed: September 08, 2021Reading time: 13 minutes


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The triangles the the neck space the topographic locations of the neck bounded by the neck muscles. The sternocleidomastoid muscle divides the neck right into the two significant neck triangles; the anterior triangle and the posterior triangle the the neck, every of lock containing a couple of subdivisions.

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The triangle of the neck space important because of their contents, as they home all the neck structures, consisting of glands, nerves, vessels and also lymph nodes. For that reason, this short article will talk about the anatomy, borders and also contents of the triangles of the neck. 

Key facts around the triangles of the neck
DefinitionTwo triangular areas found anterior and also posterior to the sternocleidomastoid muscle which save on computer the visceral frameworks of the neck.
Anterior triangleBorders:- Superior - worse border the mandible- Medial - midline that neck- Lateral - anterior boeder the sternocleidomastoid muscleSubdivisions:- Muscular (omotracheal) triangle- Carotid triangle- Submandibular triangle- Submental triangle
Posterior triangleBorders:- Anterior - posterior margin of sternocleidomastoid muscle- Posterior - anterior margin the trapezius muscle- Inferior - center one-third the clavicleSubdivisions:- Occipital triangle- Supraclavicular (omoclavicular) triangle

Contents
Anterior triangle Posterior triangleClinical significance
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Anatomical triangles

The average line that the neck divides the neck right into symmetrical halves. The sternocleidomastoid muscle, in its tilt (posterosuperior) course, more divides the neck right into anterior and also posterior triangles. The anterior triangle of the neck is more subdivided into 4 smaller triangles, when the posterior triangle is broken up right into two smaller sized triangles.

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The anterior triangle is the triangle area the the neck found anteriorly to the sternocleidomastoid muscle. That is created by the anterior border that sternocleidomastoid laterally, the typical line the the neck medially and also by the inferior border that the mandible superiorly. The apex the the anterior triangle extends towards the manubrium sterni. The anterior triangle is more subdivided right into the:

Muscular (omotracheal/infrahyoid) triangle Borders, subdivisions and contents of the anterior triangle
meaning triangular area the the neck uncovered anteriorly to the
boundaries Superior - inferior border that mandible Medial - midline of neck Lateral - anterior boeder of sternocleidomastoid muscle
Subdivisions Muscular (omotracheal) triangle Carotid triangle Submandibular triangle Submental triangle
components Muscles: thyrohyoid, sternothyroid, sternohyoid musclesOrgans: thyroid gland, parathyroid glands, larynx, trachea, esophagus, submandibular gland, caudal part of the parotid glandArteries: superior and inferior thyroid, common carotid, exterior carotid, interior carotid artery (and sinus), facial, submental, lingual arteriesVeins: anterior jugular veins, internal jugular, typical facial, lingual, premium thyroid, middle thyroid veins, facial vein, submental vein, lingual veinsNerves: vagus nerve (CN X), hypoglossal nerve (CN XII), component of sympathetic trunk, mylohyoid nerve

Muscular triangle

The muscular (omotracheal) triangle also shares one margin with the anterior triangle – the typical line of the neck. However, the muscular triangle starts at the inferior border that the human body of the hyoid bone. It has actually two posterior borders – the proximal component of the anterior border that sternocleidomastoid inferiorly and the anterior part of the superior belly of omohyoid superiorly.

borders superior - hyoid bone Lateral - remarkable belly the omohyoid and also anterior border the sternocleidomastoid Medial - midline that neck
components Muscles: thyrohyoid, sternothyroid, sternohyoidVessels: superior and inferior thyroid arteries, anterior jugular veinsViscera: thyroid gland, parathyroid glands, larynx, trachea, stomach

The apex of the muscular triangle is in ~ the intersection the sternocleidomastoid and also omohyoid muscles. The muscular triangle contains: the infrahyoid muscle (thyrohyoid, sternothyroid, sternohyoid), vessels (superior and inferior thyroid arteries, anterior jugular veins) and also viscera (thyroid and also parathyroid glands, larynx, trachea, esophagus).

Carotid triangle

similar to the muscular triangle, the carotid triangle has actually the omohyoid and also sternocleidomastoid muscle as parts of the borders. However, it is the posterior margin the the remarkable omohyoid muscle that limits the triangle anteriorly and also the anterior margin of the sternocleidomastoid posteriorly.

Borders and also contents of the carotid triangle
boundaries Anterior - superior belly of omohyoid muscle exceptional - stylohyoid and posterior ship of digastric muscles Posterior - anterior border the sternocleidomastoid muscle
contents Arteries: usual carotid, external carotid (and branches except maxillary, superficial temporal and posterior auricular), interior carotid artery (and sinus)Veins: internal jugular, common facial, lingual, exceptional thyroid, center thyroid veinsNerves: vagus nerve (CN X), hypoglossal nerve (CN XII), part of sympathetic tribe

Superiorly, the posterior belly of the digastric muscle and stylohyoid nearby the triangle. The is floored by the inferior and also middle pharyngeal constrictors, hyoglossus and also parts of thyrohyoid. That roof is developed by deep and superficial fascia, platysma and skin. This triangle contains major arteries, veins and also nerves of the neck and head.

Submandibular (digastric) triangle

prefer the anterior triangle, the digastric (submandibular) triangle is restricted superiorly by the exact same structures. That is inferior limits are formed by the posterior ship of the digastric and also stylohyoid muscle posteriorly, and the anterior belly of the digastric muscle anteriorly. The apex the the triangle rests in ~ the intermediate tendon that the digastric muscle. The floor is developed by the mylohyoid and hyoglossus, while it is roofed through skin, fascia and platysma.

Borders and contents of the submandibular (digastric) triangle
borders superior - inferior border the mandible Lateral - anterior belly of digastric muscle Medial - posterior belly of digastric muscle
components Viscera: submandibular gland and also lymph nodes (anteriorly), caudal component of the parotid gland (posteriorly)Vessels: facial artery and vein, submental artery and also vein, lingual arteries and veinsNerves: mylohyoid, hypoglossal (CN XII)

The digastric triangle houses submandibular gland and also lymph nodes (anteriorly), caudal component of the parotid gland (posteriorly), face artery and also vein, submental artery and also vein, lingual arteries and also veins, mylohyoid nerve and the hypoglossal nerve (CN XII).

Submental triangle

The submental triangle is located in between the anterior bellies of the left and right digastric muscles. The basic of the triangle is developed by the body of the hyoid bone and also its apex extends in the direction of the symphysis menti. This triangle, choose the submandibular triangle, is floored by the mylohyoid muscles and also roofed by the platysma, fascia and skin.

Borders and contents of the submental triangle
borders inferior - hyoid bone Lateral - anterior belly of digastric muscle Medial - midline the neck
contents Anterior jugular vein, submental lymph nodes

The submental triangle is populated by the small venous tributaries to the anterior jugular vein, and also the submental lymph nodes.

Posterior triangle


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The posterior triangle is a triangular area found posteriorly come the sternocleidomastoid muscle. It has three borders; anterior, posterior and also inferior borders. The anterior border is the posterior margin the the sternocleidomastoid muscle. The posterior border is the anterior margin that the trapezius muscle, while the inferior border is the center one-third of the clavicle. 

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The investing class of deep cervical fascia and integument forms the roof the the space, if the floor is covered with the prevertebral fascia along with levator scapulae, splenius capitis and also the scalene muscles. The inferior belly of omohyoid subdivides the posterior triangle right into a little supraclavicular, and also a large occipital, triangle.

Borders, subdivisions and also contents that the posterior triangle
boundaries Anterior - posterior margin of sternocleidomastoid muscle Posterior - anterior margin the trapezius muscle Inferior - center one-third that clavicle
Subdivisions Occipital triangle Supraclavicular (omoclavicular) triangle
materials Vessels: the third part of the subclavian artery, suprascapular and also transverse cervical branches that the thyrocervical trunk, outside jugular vein, lymph nodesNerves: accessory nerve (CN XI), the trunks the the brachial plexus, fibers of the cervical plexus

Occipital triangle

The anterior and posterior spare of the occipital triangle room the same as those the the posterior triangle. However, its base (inferior border) is now created by the exceptional margin that the inferior ship of the omohyoid muscle.

Borders and also contents that the occipital triangle
borders Anterior - posterior margin of sternocleidomastoid muscle Posterior - anterior margin the trapezius muscle inferior - inferior ship of omohyoid muscle
components Accessory nerve (CN XI), branches of the cervical plexus, upper most part of brachial plexus, supraclavicular nerve

The semispinalis capitis (occasionally), splenius capitis, levator scapulae and also middle scalene and posterior muscles line the floor that the occipital triangle in that craniocaudal order. The roof of the triangle is (from superficial to deep) skin, superficial and also deep fascia.

Supraclavicular (omoclavicular) triangle

Finally, the supraclavicular triangle (greater supraclavicular fossa) is the smaller sized of the 2 posterior triangles. It share anterior and inferior margins through the posterior triangle. However, that is limited superiorly by the worse border of omohyoid. Scalenus medius, the very first digitation of serratus anterior and also the very first rib are in the floor of this triangle. The roof is developed from the skin, fascia and platysma.

Borders and contents of the supraclavicular (omoclavicular) triangle
boundaries exceptional - inferior belly of omohyoid muscle Anterior - posterior leaf of sternocleidomastoid muscle Posterior - anterior leaf of trapezius muscle
materials Third part of the subclavian artery, brachial plexus trunks, nerve to subclavius muscle, lymph nodes

The subdivisions of the posterior triangle are inhabited by the regional lymph nodes, the third part of the subclavian artery, suprascapular and also transverse cervical branches the the thyrocervical trunk, external jugular vein, trunks of the brachial plexus and the fibers of the cervical plexus.

In addition, us strongly recommend the you crown your expertise by reviewing our clinical cases. Every neck triangle has a group of lymph nodes, yet what happens as soon as they become enlarged and also compress nearby structures? friend can discover that out in our situation of Horner"s Syndrome. Also, the thyroid gland contained in the anterior triangle the the neck can be impacted with one inflammatory procedure within Hashimoto"s disease. Learn about it through our article.

Solidify your knowledge around the triangle of the neck v our quiz:


Clinical significance

Knowledge that the triangles of the neck and their components are extremely important for clinical examinations and surgical procedures. These clinical and also surgical measures include, yet are not limited to:

Evaluation of the jugular venous pressureEvaluation of the pulses in a cardiovascular examEmergency airway management

Jugular venous pressure

Jugular venous press (JVP) is an indirect measure of the press within the venous system. This is feasible because the internal jugular vein has valveless communication with ideal atrium, as such blood can circulation backward right into the vessel. With the patient lying at a 30 - 45 degree angle and also their head turned to the left, an elevated JVP will show up as a collapsing pulsation in between the distal parts of the sternocleidomastoid in the supraclavicular triangle and can prolong as far as the lobule that the ear. The JVP is measured as the vertical distance from the sternal edge of Louis come the top of the pulsation. An elevated JVP (greater than 3 cm) is indicative of numerous pathologies, including however not minimal to pulmonary hypertension, hepatic congestion and also right love failure.

Carotid artery pulsation

Identification the the carotid artery pulsation is crucial in the check of the cardiovascular system. That is often compared with the pulsation that the radial artery. The pulsation of the carotid artery can be evaluate by palpating the region of the carotid triangle. Radio-carotid hold-up usually imply atypical coarctation the the aorta.

Cricothyroidotomy

A cricothyroidotomy is one emergency procedure used to establish a patent airway once other less invasive procedures (endotracheal intubation, laryngeal mask airway, etc) space contraindicated or would administer suboptimal care. The is a sterile procedure that involves incision the the cricothyroid membrane (caudal to the worse border that the thyroid cartilage and also cranial to the premium border that the cricoid cartilage). The membrane is one avascular plane deep come the an ar of the muscular triangle that allows for quick access to the airway until a official tracheostomy can be performed.


Sources

References:

Netter, frank H. Atlas Of human being Anatomy. 6th ed. Philadelphia, PA: Elsevier, 2014.Standring, Susan, Neil R Borley, and also Henry Gray. Gray"s Anatomy. 40th ed. Philadelphia, PA: Churchill Livingstone: Elsevier.

Triangles the the neck: want to learn an ext about it?

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