Subclavian (omoclavicular, supraclavicular) triangle is located below the inferior belly of the omohyoid. Its contents include the following: Brachial plexus supraclavicular portion – roots, trunk the branches of which enter this region from behind the scalenus anterior muscle. The branches include the dorsal scapular, long thoracic, sub-clavius, and suprascapular nerves.

The third part of the subclavian artery enters the subclavian triangle from behind the scalenus anterior muscle anterior to the brachial plexus. Branches include the transverse cervical and suprascapular arteries.

The subclavian vein passes superficial to scalenus anterior muscle. It receives the external jugular vein, a superficial vein that crosses the sternocleidomastoid muscle.

Anterior triangle is bound by the sternocleidomastoid muse the mid-line of the neck, and the inferior border of the body of the mandible. Muscular triangle is bound by the sternocleidomastoid muscle, the superior belly of the omohyoid muscle, and the midline of the neck. Its contents include the infrahyoid (strap) muscles, which function to control movements the hyoid bone and larynx during speech and deglutition (swallowing). Carotid (vascular) triangle is bound by the ster-nocleidomastoid muscle, the superior belly of the omohyoid muscle and the posterior belly of the digastric muscle. The carotid triangle contains the following: Internal jugular vein; Common carotid artery, bifurcates at the upper border of the thyroid cartilage (i. e., vertebral level C3) to form the internal and external carotid arteries. The external carotid artery has six branches (i. e., the superior thyroid; the ascending pharyngeal, the lingual, the facial, the occipital, and the posterior auricular arteries). The supply structures of the neck and face; vagus nerve; hypoglossal nerve; internal and external laryngeal branches of the superior laryngeal branch of the vagus nerve. The internal laryge-al nerve conveys sensory information from the laryngeal mucosa above the level of the vocal folds, and the external laryngeal nerve supplies motor fibers to the cricothyroid, an intrinsic muscle of the larynx. Digastric (submandibular) triangle is bound by the anterior and posterior bellies of the digastric muscle and the inferi or border of the body of the mandible. The floor of this tri angle is formed by the hyoglos-sus and mylohyoid muscles. It contains the submandibular salivary gland. Submental triangle is bound by the anterior belly of the digastric muscle, the hyoid bone, and the midline of the neck. The floor of this triangle is formed by the mylohyoid muscle. It contains the submental lymph nodes. Root of neck: This area communicates with the superior medi astinum through the thoracic inlet. Structures of the region include the following: subclavian artery and vein. The subclavian artery passes poste rior to the scalenus anterior muscle, and the vein passes ante rior to it. Branches of the artery include: vertebral artery; thyrocervical trunk, which gives rise to the inferior thyroid, the transverse cervical, and the suprascapular arteries; Internal thoracic artery.