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Digastric Muscle in 3D ANIMATION Origin Insertion Actions Nerve Supply | Head & Neck Anatomy

Digastric Muscle in 3D Origin Insertion Actions Nerve Supply Deepak Mehra Medical Videos Digastric is a small paired muscle located in the anterior compartment of the neck. It belongs to a group of muscles called the suprahyoid muscles. Besides the digastric, this group also contains the mylohyoid, geniohyoid and stylohyoid muscles. As the name suprahyoid implies, these muscles are found superior to the hyoid bone and together with the adjacent tissue they form the floor of the mouth. Another hint about the digastric muscle is found in its own name. It is derived from the Greek word “dis” meaning double or twofold, and Latin “gaster” meaning belly, which perfectly describes the composition of this muscle as having two muscle bellies. Digastric Muscle: Origin So where does this muscle begin? Since the digastric muscle has two different bellies, it has two different points of origin. 1. The anterior (front) belly originates from inner, back surface of the mandible (lower jaw) in an area called the digastric fossa. The digastric fossa is located on the inner jaw, right behind the middle point of the chin. 2. The posterior (back) belly of the digastric muscle originates from the mastoid process of the temporal bone. The mastoid process is a cone shaped bone that protrudes from a bone located at the side of the skull called the temporal bone. Digastric Muscle: Insertion So where does the digastric muscle end? The insertion point of a muscle refers to the location of the body where a muscle ends or attaches to another body part. The digastric muscle inserts on the hyoid bone, which is a horseshoe-shaped bone located in the middle front of the neck just above the larynx/voice box. The digastric muscle inserts on the hyoid bone by the tendon that connects the anterior and posterior bellies of this muscle. Digastric Muscle: Action There are two main actions or movements caused by the digastric muscle: Opening the lower jaw: The digastric muscle depresses the mandible/lower jaw by pulling it down. Aides in swallowing: During a swallow, the digastric muscle elevates the hyoid bone which helps the movement of substances down the throat. Innervation: A characteristic feature of the digastric muscle is that its bellies have different embryologic origins, and hence different innervations. The anterior belly is derived from the first pharyngeal arch and is therefore innervated by the nerve to mylohyoid muscle, a branch of the inferior alveolar nerve that arises from the mandibular nerve. The posterior belly of the digastric muscle is derived from the mesoderm of the second pharyngeal arch and is therefore innervated by the digastric branch of the facial nerve (cranial nerve 7). Blood supply The anterior belly of the digastric muscle is supplied mainly by the submental artery of the facial artery, while the posterior belly receives its arterial blood supply from the posterior auricular and occipital arteries. Relations As the posterior belly of digastric descends towards the hyoid bone, it travels closely behind (posterior) the stylohyoid muscle. Later it passes through this same muscle. Also closely related to the posterior belly is the neurovascular bundle of the neck, consisting of the internal jugular vein, external and internal carotid arteries, and vagus, glossopharyngeal and hypoglossal nerves. These structures pass deep to the posterior belly of the digastric muscle. The digastric muscle divides the anterior triangle of the neck into three smaller divisions: the carotid triangle, the submental triangle and the submandibular triangle. Carotid triangle: The posterior belly of digastric muscle forms the superior border of the carotid triangle. This paired triangle contains some very important structures, such as the common carotid artery, internal carotid artery and external carotid artery. Submental triangle: This unpaired triangle is bordered laterally by the anterior bellies of digastric muscles on each side, and inferiorly by the body of the hyoid bone. This triangle contains submental lymph nodes, submental veins and jugular veins. Submandibular triangle: This paired triangle is also known as the digastric triangle, since its borders are formed by the anterior and posterior bellies of digastric muscle, along with the inferior border of the mandible. This triangle contains structures such as the submandibular gland and submandibular lymph nodes Subscribe Now : http://bit.ly/VipinMehra