Anterior Triangle, Anatomy, Borders And Contents
The anterior triangle is bounded by the anterior border of the sternocleidomastoid muscle. Its superior border is the inferior border of the mandible. Medially, the boundary is the midline of the neck. Read the article to know more.
Nivedita Dar4 Dec, 2024
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Anterior triangle: An important anatomical landmark in Neck
The anterior triangle is a region located at the front of the neck. It is found anteriorly to the sternocleidomastoid muscle. Its borders are contributed by sternocleidomastoid muscle on the side, middle line of the neck medially, and by the inferior border of the mandible on the superior side. Apex of the triangle extends upto the Manubrium of the Breast Bone/ Sternum. Anterior Triangle has further subdivisions which are Infrahyoid triangle , Carotid triangle , Submandibular triangle and Sub mental triangleMuscular triangle:
The muscular triangle is a smaller subdivision within the anterior triangle of the neck. It is named for the muscles that it contains.Boundaries of muscular triangle
Muscular triangle has three boundaries namely, medial boundary which is contributed by midline of the neck, Superolateral boundary is contributed by superior belly of the omohyoid muscle and Inferolateral boundary formed by anterior border of the sternocleidomastoid muscle.Contents
Muscular triangle contains many important structures like muscles such as sternohyoid, sternothyroid, thyrohyoid and superior belly of omohyoid . Some important viscera are also present like thyroid gland, parathyroid gland, trachea and esophagus. Some important nerves and blood vessels are also present.Carotid Triangle
The carotid triangle is an important region in the neck. This region is one of the paired triangles within the neck’s anterior triangle, situated anterolaterally on each side of the neck. It is very important both clinically and surgically.Borders
The carotid triangle is delineated by three primary borders Anterior inferior border which is contributed by the superior belly of the omohyoid muscle. Anterosuperior border is defined by the posterior belly of the digastric muscle, extending from the notch of the temporal bone to the hyoid bone. And posterior border is is formed by the sternocleidomastoid muscle, which extends from the mastoid process of the temporal bone to the clavicle and sternum bones.The floor of the carotid triangle is contributed by several structures, including parts of the thyrohyoid, hyoglossus, and inferior and middle constrictor muscles of pharynx.Contents
The carotid triangle contains very important vascular and neural structures, making it crucial for surgical and diagnostic purposes. The bifurcation of the carotid artery into the external and internal carotid arteries takes place in the carotid triangle. Arteries are superior thyroid artery, lingual artery, facial artery, occipital artery and ascending pharyngeal artery.These arteries are accompanied by corresponding veins that drain into the internal jugular vein (IJV). Nerves in the carotid triangle are vagus nerve, hypoglossal nerve, accessory nerve and ansa cervicalis.Carotid Sheath
The carotid sheath is formed by the middle cervical fascia (fascia of the neck). It encloses the vagus nerve, the internal jugular vein, the common carotid artery, and deep cervical lymph nodes. Superficial to the carotid sheath, the hypoglossal nerve also descends within the neck triangle, along with the accessory nerve (CN XI) and the ansa cervicalis profunda. These nerves are integral to the motor function of various neck muscles and the tongue.Clinical Significance
The carotid triangle holds critical importance in clinical settings. Surgeons often focus on this area during procedures involving the carotid arteries, such as carotid endarterectomy, which is performed to remove atherosclerotic plaque from the carotid arteries to prevent stroke. Understanding the precise anatomical boundaries and contents of the carotid triangle is essential for avoiding complications during such surgeries.Submandibular triangle
The submandibular triangle, also known as the digastric triangle, is one of the smaller subdivisions of the anterior triangle of the neck. It is named for its location beneath the mandible (lower jaw) and its association with the submandibular gland.Borders
Its boundaries are superior, anterior and posterior which are contributed by Inferior border of the mandible, Anterior belly of the digastric muscle and Posterior belly of the digastric muscle and the stylohyoid muscle.Contents
It contains submandibular glands along with numerous muscles and many important neurovascular structures. Most importantly it also contains submandibular lymph nodes which are assessed clinically in many diseases.Sub mental triangle
The submental triangle is another subdivision of the anterior triangle of the neck. It is a smaller triangular area situated beneath the chin, hence the name "submental."Borders
Sub mental triangle has three borders namely lateral boundaries, inferior boundaries and superior boundaries which are contributed by anterior bellies of the right and left digastric muscles and body of the hyoid bone. It contains mylohyoid muscle and some neurovascular structures, it contains submental lymph nodes which are part of the lymphatic system and are involved in draining lymph from the central lower lip, the floor of the mouth, and the apex of the tongue.Anterior Triangle FAQs
What structures form the floor of the carotid triangle?
The floor of the carotid triangle is formed by different important muscle parts such as thyrohyoid, hyoglossus, and the inferior and middle constrictor
muscles.
What is the carotid triangle and why is it clinically significant?
The carotid triangle is a region in the neck which is situated anterolaterally on each side of the neck. It is significant because it contains important vascular and neural structures, making it a crucial area for surgeries and diagnostic procedures.
What are some common pathologies associated with the anterior triangle of the neck?
Common conditions include:
Thyroid disorders: Goiter, thyroiditis, and thyroid cancer.
Lymphadenopathy: Enlarged lymph nodes due to infections or malignancies.
Carotid artery disease: Such as stenosis or aneurysm.
Salivary gland disorders: Sialadenitis or tumors of the submandibular gland.
What is the importance of the submandibular triangle?
The submandibular triangle contains the submandibular gland, lymph nodes, and parts of the facial artery and vein. It is significant for:
Examination and biopsy of submandibular gland and lymph nodes.
Surgical procedures Involving the submandibular gland, including excision in cases of tumors or chronic infections.
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