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The digastric muscle, also known as the digastricus, is a small but important muscle in the neck, which is involved in complex jaw actions such as speaking, swallowing, chewing, and breathing. The digastric muscle has two bellies, the anterior and posterior belly, which are joined by an intermediate tendon. The primary function of the digastric muscle is to elevate the hyoid bone and depress or lower the mandible, helping to open the mouth. This muscle also aids in closing the epiglottis during swallowing, preventing the inhalation of food or liquid.
| Characteristics | Values |
|---|---|
| Muscle name origin | "Digastric" is derived from the Greek "dis" meaning double or twofold, and the Latin "gaster" meaning belly. |
| Muscle structure | Comprised of two parts: the anterior and posterior belly, joined by an intermediate tendon. |
| Muscle function | Depresses the mandible, aiding the act of opening the mouth. When the mandible is fixed, the digastric muscle elevates the hyoid bone and the larynx. |
| Muscle innervation | The anterior belly is innervated by the trigeminal nerve (cranial nerve V) and the posterior belly by the facial nerve (cranial nerve VII). |
| Muscle attachments | The anterior belly attaches at the digastric fossa of the mandible, and the posterior belly at the mastoid notch of the temporal bone. |
| Muscle variations | The anterior belly has more anatomical variations than the posterior belly, with unilateral variants being more common than bilateral variants. |
| Muscle triangles | Divides the anterior triangle of the neck into three or four smaller triangles: the submandibular triangle, the carotid triangle, the submental triangle, and the inferior carotid triangle. |
| Muscle exercises | To relieve tension, jut the chin forward, tilt the head upwards, and place the thumbs under the chin while pressing the tongue against the roof of the mouth. |
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What You'll Learn
- The digastric muscle is involved in complex jaw actions like speaking, swallowing, chewing, and breathing
- The digastric muscle is made up of two parts: the anterior and posterior bellies, joined by a tendon
- The digastric muscle is innervated by the trigeminal nerve, with the anterior belly innervated by the mandibular division
- The digastric muscle is involved in depressing and retruding the mandible, helping to open the mouth
- The digastric muscle is a small muscle situated under the jaw and is one of six key muscles that assist in jaw movement
The digastric muscle is involved in complex jaw actions like speaking, swallowing, chewing, and breathing
The digastric muscle is a bilaterally paired suprahyoid muscle located under the jaw. It is named digastric as it has two bellies, the anterior and the posterior. The posterior belly is attached to the mastoid notch of the temporal bone, and the anterior belly is attached to the digastric fossa of the mandible. The two bellies are united by an intermediate tendon which is held in a loop that attaches to the hyoid bone.
The digastric muscle also elevates the hyoid bone and the larynx. The superior movement of the hyoid and larynx results in the lowering or closing of the epiglottis, blocking the entrance to the trachea and preventing the inhalation of food or liquid during swallowing. This action of the digastric muscle is thus crucial for breathing, as it prevents food or liquid from entering the trachea.
The digastric muscle's unique structure enables it to facilitate jaw depression, which is a fundamental component of the mastication process. As the muscle contracts, it harmonizes with the surrounding musculature to achieve a seamless rhythm in chewing. The coordination of the digastric muscle with the suprahyoid and infrahyoid muscle groups enhances its function. These groups work together to stabilize the hyoid bone, providing a stable foundation for lower jaw movements. This stabilization is essential for the effective opening and closing of the mouth, ensuring efficient and well-regulated chewing.
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The digastric muscle is made up of two parts: the anterior and posterior bellies, joined by a tendon
The digastric muscle is a bilaterally paired suprahyoid muscle located under the jaw. It is named the digastric muscle because it has two parts, or "bellies", that are united by an intermediate tendon. The two bellies of the digastric muscle are the anterior belly and the posterior belly. The name "digastric" is derived from the Greek word "dis", meaning double or twofold, and the Latin "gaster", meaning belly.
The posterior belly of the digastric muscle is attached to the mastoid notch of the temporal bone, and the anterior belly is attached to the digastric fossa of the mandible. The two bellies meet at the intermediate tendon, which is held in a loop that attaches to the hyoid bone. The intermediate tendon of the digastric muscle is encircled by a U-shaped fibrous tissue sling, formed by a thickening of the investing layer of the deep cervical fascia. This sling acts as a pulley, allowing the intermediate tendon to slide anteriorly and posteriorly.
The digastric muscle is involved in any complex jaw action, such as speaking, swallowing, chewing, and breathing. The posterior belly is particularly functionally involved in swallowing and chewing. The digastric muscle aids the act of opening the mouth by depressing the mandible when the hyoid bone is held in place. When the mandible is fixed, the digastric muscle elevates the hyoid bone and the larynx. This results in the lowering or closing of the epiglottis, blocking the entrance to the trachea and preventing the inhalation of food or liquid during swallowing.
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The digastric muscle is innervated by the trigeminal nerve, with the anterior belly innervated by the mandibular division
The digastric muscle is a small, paired suprahyoid muscle located under the jaw. It is named digastric as it has two bellies, namely the anterior and posterior belly, which are united by an intermediate tendon. The digastric muscle is innervated by the trigeminal nerve, with the anterior belly innervated by the mandibular division.
The embryological origins of the two bellies of the digastric muscle differ, with the anterior belly derived from the first brachial arch and the posterior belly from the second brachial arch. Consequently, they are supplied by different nerves and arteries. The anterior belly is innervated by the mandibular nerve (also known as cranial nerve V), which is a branch of the trigeminal nerve. It receives motor innervation from the mylohyoid nerve, a branch of the inferior alveolar nerve, which is in turn a branch of the mandibular division of the trigeminal nerve. The posterior belly is innervated by the facial nerve (cranial nerve VII).
The anterior belly of the digastric muscle has more anatomical variations than the posterior belly, with unilateral variants being more common than bilateral variants. These variations include accessory muscle bellies with different origins and insertions, as well as nerve supply variations. For example, the facial and mylohyoid nerves may innervate the anterior belly. The anterior belly may also be double, or it may fuse with the mylohyoid muscle. It originates from the digastric fossa of the mandible, near the midline, and extends inferoposteriorly towards the intermediate tendon.
The posterior belly of the digastric muscle is attached to the mastoid notch of the temporal bone and descends towards the hyoid bone, passing through the stylohyoid muscle. It is functionally involved in swallowing and chewing. The posterior belly is also associated with the neurovascular bundle of the neck, which includes the internal jugular vein, external and internal carotid arteries, and several nerves. The digastric muscle as a whole plays a role in complex jaw actions such as speaking, swallowing, chewing, and breathing. It depresses the mandible when the hyoid bone is held in place, aiding in opening the mouth, and may also elevate the hyoid bone.
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The digastric muscle is involved in depressing and retruding the mandible, helping to open the mouth
The digastric muscle is a small but important muscle in the neck, with a unique composition. It is comprised of two parts, or bellies, with different origins and functions. The name "digastric" is derived from the Greek "dis", meaning double or twofold, and the Latin "gaster", meaning belly, reflecting its double-bellied structure.
The two bellies of the digastric muscle are the anterior belly and the posterior belly. The anterior belly is the smaller of the two and is located on the lower border of the mandible, near the midline. It is derived from the first brachial arch and is innervated by the trigeminal nerve (cranial nerve V). The posterior belly, meanwhile, is derived from the second brachial arch and is innervated by the facial nerve (cranial nerve VII). It attaches at the mastoid notch of the temporal bone, located on the inferior surface of the skull, and extends towards the hyoid bone.
The digastric muscle is one of six key muscles that assist in the movement of the human jaw. It is part of the suprahyoid muscles group, which also includes the mylohyoid, geniohyoid, and stylohyoid muscles. The digastric muscle's role in depressing the mandible is essential for jaw function, and it works in coordination with other muscles to perform these vital actions.
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The digastric muscle is a small muscle situated under the jaw and is one of six key muscles that assist in jaw movement
The digastric muscle, also known as the digastricus, is a small but important muscle located in the neck, under the jaw. It is one of six key muscles that assist in the movement of the human jaw. The digastric muscle has two bellies, the anterior and the posterior, which are joined by an intermediate tendon. The name "digastric" is derived from the Greek word "dis", meaning double or twofold, and the Latin "gaster", meaning belly. This name aptly describes the muscle's double-bellied structure.
The anterior belly of the digastric muscle is the smaller of the two structures and is located on the lower border of the mandible, near the midline. It originates from the digastric fossa of the mandible and extends towards the intermediate tendon. The posterior belly, on the other hand, originates at the medial surface of the mastoid notch of the temporal bone and travels towards the hyoid bone, eventually attaching to the intermediate tendon. The posterior belly also serves as a boundary for the carotid triangle, an area where the facial artery branches from the external carotid.
The digastric muscle plays a crucial role in jaw movement, particularly in opening the mouth by depressing or lowering the mandible. This action is essential for various functions such as chewing, swallowing, and speech. Additionally, the digastric muscle is involved in elevating the hyoid bone, which in turn helps to close the epiglottis during swallowing, preventing the inhalation of food or liquid.
The digastric muscle is also significant in neck anatomy. It divides the anterior triangle of the neck into smaller triangles: the submandibular triangle (digastric triangle), the carotid triangle, the submental triangle (suprahyoid triangle), and the inferior carotid triangle (muscular triangle). These triangles house important structures such as the submandibular gland, lymph nodes, and various arteries and nerves.
The digastric muscle can be prone to pain and discomfort due to various conditions, including muscle tears, sprains, and injuries caused by overuse. Exercises such as jutting the chin forward and tilting the head upwards, or pushing the bottom of the jaw forward against resistance, can help relieve tension and strengthen the digastric muscle.
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Frequently asked questions
The digastric muscle is a small muscle found in the neck, under the jaw. It has two bellies, the anterior and the posterior.
The digastric muscle helps to open the mouth by depressing or lowering the mandible. When the mandible is fixed, the digastric muscle elevates the hyoid bone and the larynx with it, which results in the lowering or closing of the epiglottis.
Pain or discomfort in the digastric muscle may be due to muscle tears, sprains, or injuries caused by overuse. Treatment typically involves pain-relief medications or, in some cases, muscle repair surgery.
