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The digastric muscle is a small paired muscle in the anterior compartment of the neck, consisting of two muscular bellies: the anterior belly and the posterior belly. The two bellies have different embryological origins and, consequently, different innervations. The anterior belly is derived from the first brachial arch and is innervated by the nerve to the mylohyoid muscle, a branch of the inferior alveolar nerve (CN V3) arising from the mandibular nerve. The posterior belly, on the other hand, is derived from the mesoderm of the second pharyngeal arch and is innervated by the digastric branch of the facial nerve (CN VII).
| Characteristics | Values |
|---|---|
| Muscle type | Suprahyoid |
| Muscle bellies | Anterior and posterior |
| Innervation | Anterior belly: Mylohyoid nerve (branch of inferior alveolar nerve, which is a branch of the mandibular nerve) |
| Posterior belly: Digastric branch of the facial nerve (cranial nerve 7) | |
| Embryological origin | Anterior belly: First brachial arch |
| Posterior belly: Second brachial arch | |
| Function | Depresses the mandible and elevates the hyoid bone |
| Involved in complex jaw actions such as speaking, swallowing, chewing, and breathing | |
| Divides the anterior triangle of the neck into three or four smaller triangles |
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What You'll Learn
- The digastric muscle's anterior belly is innervated by the mylohyoid nerve
- The posterior belly is innervated by the digastric branch of the facial nerve
- The digastric muscle is a suprahyoid muscle of the neck
- The muscle's embryological origins are different, with the anterior belly derived from the first pharyngeal arch and the posterior belly from the second
- The digastric muscle is involved in complex jaw actions like chewing, swallowing, speaking and breathing
The digastric muscle's anterior belly is innervated by the mylohyoid nerve
The digastric muscle is a small, paired muscle located in the anterior compartment of the neck. It is involved in any complex jaw action, such as speaking, swallowing, chewing, and breathing. The digastric muscle is comprised of two parts: the anterior and posterior bellies, which have different embryological origins and, consequently, different innervations.
The anterior belly of the digastric muscle is derived from the first brachial arch and is innervated by the mylohyoid nerve. The mylohyoid nerve is a mixed nerve of the head that provides motor innervation to the mylohyoid muscle and the anterior belly of the digastric muscle. It is a branch of the inferior alveolar nerve, which is a derivative of neural crest cells in the first brachial arch. The inferior alveolar nerve, in turn, is a branch of the mandibular nerve (CN V3), which is a division of the trigeminal nerve (CN V)sensory innervation of the face and splits into three main branches: the ophthalmic nerve (CN V1), the maxillary nerve (CN V2), and the mandibular nerve (CN V3).
The mylohyoid nerve provides sensory innervation to the skin of the centre of the submental area and, sometimes, the mandibular (lower) molar teeth. During oral procedures, the mylohyoid nerve needs to be blocked to prevent pain. The mylohyoid nerve travels closely with the medial division of the submandibular glands, ultimately settling between the mylohyoid muscle and the anterior belly of the digastric muscle.
The posterior belly of the digastric muscle is derived from the mesoderm of the second pharyngeal arch and is innervated by the digastric branch of the facial nerve (CN VII). The posterior belly is particularly functionally involved in swallowing and chewing.
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The posterior belly is innervated by the digastric branch of the facial nerve
The digastric muscle is a small paired muscle located in the anterior compartment of the neck. It is part of a group of muscles called the suprahyoid muscles, which are found superior to the hyoid bone. The digastric muscle itself is comprised of two parts: the anterior and posterior bellies, which are joined by an intermediate tendon.
The posterior belly of the digastric muscle is derived from the mesoderm of the second pharyngeal arch. It is situated posterior to the parotid gland and the facial nerve. This part of the muscle is involved in swallowing and chewing. The posterior belly attaches at the mastoid notch of the temporal bone and extends anteroinferiorly toward the intermediate tendon. The tendon may pass through the stylohyoid muscle.
The posterior belly of the digastric muscle is innervated by the digastric branch of the facial nerve (cranial nerve 7). It is supplied arterially by the posterior auricular and occipital arteries.
The digastric branch of the facial nerve is responsible for innervating the posterior belly of the digastric muscle. This nerve supply is essential for the proper functioning of the muscle, particularly during complex jaw actions such as swallowing and chewing.
The digastric muscle as a whole plays a crucial role in jaw movement and function. It depresses the mandible and elevates the hyoid bone, contributing to a range of oral activities, including speaking, swallowing, chewing, and breathing.
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The digastric muscle is a suprahyoid muscle of the neck
The digastric muscle is comprised of two muscular bellies: the anterior belly and the posterior belly. These bellies unite as the intermediate tendon, which attaches to the hyoid bone. The intermediate tendon acts as a pulley, allowing the tendon to slide anteriorly and posteriorly. The anterior belly arises from the digastric fossa of the mandible, while the posterior belly arises from the mastoid process of the temporal bone.
The two bellies of the digastric muscle have different embryological origins and, therefore, different innervations. The anterior belly is derived from the first brachial arch and is innervated by the nerve to the mylohyoid muscle, a branch of the inferior alveolar nerve (CN V3) that arises from the mandibular nerve. The posterior belly is derived from the mesoderm of the second brachial arch and is innervated by the digastric branch of the facial nerve (CN VII).
The digastric muscle is involved in complex jaw actions such as speaking, swallowing, chewing, and breathing. It depresses the mandible and elevates the hyoid bone, which initiates swallowing. The digastric muscle also divides the anterior triangle of the neck into three or four smaller triangles: the submandibular triangle (also known as the digastric triangle), the carotid triangle, the submental triangle, and the inferior carotid triangle (or muscular triangle).
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The muscle's embryological origins are different, with the anterior belly derived from the first pharyngeal arch and the posterior belly from the second
The digastric is a small paired muscle located in the anterior compartment of the neck. It is comprised of two parts: the anterior belly and the posterior belly, joined by an intermediate tendon. The muscle gets its name from the Greek word "dis", meaning double or twofold, and the Latin "gaster", meaning belly.
The embryological origins of the two bellies are different. The anterior belly is derived from the first pharyngeal arch, also known as the mandibular arch. This arch is the first to form and separates the mouth pit or stomodeum from the pericardium. The mandibular nerve is the post-trematic nerve of the first arch. The anterior belly is innervated by the nerve to the mylohyoid muscle, a branch of the inferior alveolar nerve that arises from the mandibular nerve. The anterior belly is supplied mainly by the submental artery of the facial artery.
The posterior belly is derived from the mesoderm of the second pharyngeal arch, also known as the hyoid arch. This arch becomes the hyoid and jaw support. The facial nerve is the pre-trematic nerve of the first arch, and the chorda tympani is a branch of the facial nerve. The posterior belly is innervated by the digastric branch of the facial nerve (cranial nerve 7). The posterior belly receives its arterial blood supply from the posterior auricular and occipital arteries.
The digastric muscles are involved in complex jaw actions such as speaking, swallowing, chewing, and breathing. They are also important surgical landmarks during neck dissections and are valuable in neck reconstruction procedures.
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The digastric muscle is involved in complex jaw actions like chewing, swallowing, speaking and breathing
The digastric muscle is a small, paired muscle located in the anterior compartment of the neck. It is part of a group of muscles called the suprahyoid muscles, which form the floor of the mouth. The digastric muscle is unique in that it has two muscle bellies, the anterior and posterior, which unite at an intermediate tendon that attaches to the hyoid bone. The hyoid bone acts as a pivotal point for various muscular attachments.
The digastric muscle is involved in complex jaw actions like chewing, swallowing, speaking, and breathing. When it contracts, it works in harmony with the surrounding musculature, including the suprahyoid and infrahyoid muscle groups, to achieve a seamless rhythm in chewing. This coordination helps to stabilize the hyoid bone, providing a stable foundation for lower jaw movements. The depression of the mandible by the digastric muscle aids in opening the mouth, which is essential for chewing and speaking.
The anterior belly of the digastric muscle originates from the digastric fossa of the mandible, while the posterior belly arises from the mastoid notch of the temporal bone. The posterior belly is longer than the anterior belly. The two bellies have different embryological origins, which result in different innervations. The anterior belly is innervated by the mandibular nerve (CN V), while the posterior belly is innervated by the facial nerve (CN VII).
The digastric muscle also plays a role in swallowing. As the mandible is fixed, the muscle elevates the hyoid bone and the larynx, resulting in the lowering of the epiglottis. This blocks the entrance to the trachea, preventing the inhalation of food or liquid during swallowing. The digastric muscle, therefore, contributes to safe and efficient swallowing.
Additionally, the digastric muscle's role in jaw depression and stabilization can indirectly impact breathing. The muscle's ability to depress the mandible and stabilize the hyoid bone can influence the position and movement of the jaw, which is connected to the airway and can affect breathing. While the digastric muscle does not directly control respiration, its impact on jaw position and movement can have secondary effects on breathing.
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Frequently asked questions
The digastric muscle is a small paired muscle located in the anterior compartment of the neck. It is a suprahyoid muscle, which means it is located superior to the hyoid bone. It is involved in complex jaw actions such as speaking, swallowing, chewing and breathing.
The digastric muscle is comprised of two parts: the anterior belly and the posterior belly. These two bellies are connected by an intermediate tendon, which is attached to the hyoid bone.
The anterior belly of the digastric muscle is innervated by the mylohyoid nerve, a branch of the inferior alveolar nerve, which is in turn a branch of the mandibular nerve (CN V3 or CN V).
The posterior belly of the digastric muscle is innervated by the digastric branch of the facial nerve (CN VII or CN 7).
