Logan Steele
The digastric muscle is a small paired muscle in the anterior compartment of the neck. It is involved in complex jaw actions such as speaking, swallowing, chewing, and breathing. The muscle is comprised of two parts, the anterior and posterior bellies, which have different embryologic origins and, therefore, different innervations. The nerve innervating the digastric muscle is a topic of interest as the two bellies are supplied by different cranial nerves.
| Characteristics | Values |
|---|---|
| Muscle type | Suprahyoid muscle |
| Muscle group | Mylohyoid, geniohyoid, stylohyoid |
| Muscle parts | Anterior and posterior belly |
| Anterior belly embryologic origin | First pharyngeal arch |
| Anterior belly innervation | Nerve to mylohyoid muscle, a branch of the inferior alveolar nerve (mandibular nerve) |
| Posterior belly embryologic origin | Mesoderm of the second pharyngeal arch |
| Posterior belly innervation | Digastric branch of the facial nerve (cranial nerve 7) |
| Anterior belly blood supply | Submental artery of the facial artery |
| Posterior belly blood supply | Posterior auricular and occipital arteries |
| Function | Depresses the mandible and elevates the hyoid bone |
| Function in complex jaw actions | Involved in speaking, swallowing, chewing, and breathing |
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What You'll Learn
- The anterior belly of the digastric muscle is innervated by the mylohyoid nerve
- The posterior belly of the digastric muscle is innervated by the facial nerve
- The digastric muscle is involved in complex jaw actions like speaking, swallowing, chewing, and breathing
- The digastric muscle is part of a group of muscles called the suprahyoid muscles
- The digastric muscle is comprised of two bellies, anterior and posterior, joined by an intermediate tendon
The anterior belly of the digastric muscle is innervated by the mylohyoid nerve
The digastric muscle is a small, paired suprahyoid muscle located in the anterior compartment of the neck. It is comprised of two parts, the anterior and posterior bellies, which are joined by an intermediate tendon. The anterior belly of the digastric muscle is innervated by the mylohyoid nerve, a branch of the inferior alveolar nerve, which arises from the mandibular nerve. The posterior belly of the digastric muscle is innervated by the digastric branch of the facial nerve.
The digastric muscle is involved in any complex jaw action, such as speaking, swallowing, chewing, and breathing. The muscle is responsible for depressing the mandible and elevating the hyoid bone. The anterior belly of the digastric muscle is derived from the first pharyngeal arch, while the posterior belly is derived from the mesoderm of the second pharyngeal arch. This difference in embryologic origin results in different innervations for the two bellies of the digastric muscle.
The mylohyoid nerve is responsible for innervating the anterior belly of the digastric muscle. In some cases, the anterior belly can be innervated by both the mylohyoid nerve and the facial nerve. The mylohyoid nerve is a branch of the inferior alveolar nerve, which is, in turn, a branch of the mandibular division of the trigeminal nerve. The trigeminal nerve is the fifth cranial nerve, also known as CN V or CN V3.
The digastric muscle divides the anterior triangle of the neck into four smaller triangles: the submandibular triangle (also known as the digastric triangle), the carotid triangle, the submental triangle (or suprahyoid triangle), and the inferior carotid triangle (or muscular triangle). The submental triangle is formed by the hyoid bone and the two anterior bellies of the digastric muscle. This triangle contains important structures such as the submental lymph nodes and the anterior jugular vein.
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The posterior belly of the digastric muscle is innervated by the facial nerve
The digastric muscle is a suprahyoid muscle of the neck that consists of two muscular bellies: the anterior belly and the posterior belly. The anterior belly is derived from the first pharyngeal arch and is innervated by the nerve to the mylohyoid muscle, a branch of the inferior alveolar nerve.
The posterior belly of the digastric muscle, on the other hand, has a different embryological origin. It is derived from the mesoderm of the second pharyngeal arch. This distinct origin results in a different innervation pattern. Specifically, the posterior belly is innervated by the facial nerve, also known as cranial nerve 7.
The facial nerve, in the context of the posterior belly's innervation, is specifically referred to as the digastric branch of the facial nerve. This nerve plays a crucial role in the functioning of the posterior belly, which is particularly active during swallowing and chewing. The posterior belly of the digastric muscle is closely associated with the hyoid bone, and its movement helps to elevate the hyoid bone while depressing the mandible.
The digastric muscle as a whole is involved in complex jaw actions, including speaking, swallowing, chewing, and breathing. The muscle's name, derived from the Greek "dis" (meaning double or twofold) and the Latin "gaster" (meaning belly), aptly describes its structure, which consists of two bellies joined by an intermediate tendon. This tendon attaches to the hyoid bone, contributing to the muscle's role in jaw and hyoid bone movements.
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The digastric muscle is involved in complex jaw actions like speaking, swallowing, chewing, and breathing
The digastric muscle is a small, paired suprahyoid muscle located in the anterior compartment of the neck, under the jaw. It is so-called because it has two bellies, derived from the Greek "dis", meaning double or twofold, and the Latin "gaster", meaning belly. The anterior belly is derived from the first pharyngeal arch and is innervated by the nerve to the mylohyoid muscle, a branch of the inferior alveolar nerve that arises from the mandibular nerve. The posterior belly is derived from the mesoderm of the second pharyngeal arch and is innervated by the digastric branch of the facial nerve.
The digastric muscle is also involved in breathing, as it helps to elevate the hyoid bone and the larynx, which are important for maintaining a clear airway. Additionally, the muscle's proximity to the sub-mandibular salivary gland and its role in depressing the mandible may also have implications for breathing and airway management.
The digastric muscle works in coordination with other suprahyoid muscles, such as the mylohyoid, geniohyoid, and stylohyoid muscles, to perform these complex jaw actions. The muscle's unique embryological origins and innervations contribute to its functionality in these processes.
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The digastric muscle is part of a group of muscles called the suprahyoid muscles
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 suprahyoid muscles include the digastric, mylohyoid, geniohyoid, and stylohyoid muscles. Together with adjacent tissue, these muscles form the floor of the mouth.
The digastric muscle is comprised of two parts: the anterior belly and the posterior belly, which are joined by an intermediate tendon. The 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 is anchored on the superior side of the body of the hyoid bone and acts as a pulley, allowing the intermediate tendon to slide anteriorly and posteriorly.
The anterior belly of the digastric muscle originates from the digastric fossa of the mandible, while the posterior belly arises from the mastoid process of the temporal bone. The two bellies unite above the hyoid bone as the intermediate tendon. The digastric muscle gets its name from the Greek word "dis," meaning double or twofold, and the Latin "gaster," meaning belly, which describes its composition of two muscle bellies.
The anterior belly of the digastric muscle is innervated by the nerve to the mylohyoid muscle, a branch of the inferior alveolar nerve that arises from the mandibular nerve. The posterior belly of the digastric muscle is innervated by the digastric branch of the facial nerve (cranial nerve 7). The anterior belly receives its arterial blood supply mainly from the submental artery of the facial artery, while the posterior belly is supplied by the posterior auricular and occipital arteries.
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The digastric muscle is comprised of two bellies, anterior and posterior, joined by an intermediate tendon
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 also includes the mylohyoid, geniohyoid, and stylohyoid muscles. The digastric muscle is unique in that it is comprised of two bellies: the anterior and posterior. These bellies have different embryological origins and, therefore, different innervations.
The anterior belly of the digastric muscle originates from the digastric fossa of the mandible's lower border, near the midline close to the mandibular symphysis. It extends posteroinferiorly from its origin toward the intermediate tendon. The anterior belly receives motor innervation from the mylohyoid nerve, a branch of the inferior alveolar nerve, which is derived from the mandibular nerve. The mylohyoid nerve is a branch of the trigeminal nerve (CN V or CN V3). The anterior belly may be double, and additional slips from this belly may pass to the jaw or mylohyoideus, or decussate with a similar slip on the opposite side.
The posterior belly of the digastric muscle originates at the medial surface of the mastoid notch of the temporal bone. It travels anteroinferiorly toward the hyoid bone, piercing the stylohyoid muscle before attaching to the intermediate tendon of the digastric muscle. The posterior belly is supplied by the digastric branch of the facial nerve (CN VII). The posterior belly is situated posterior to the parotid gland and is functionally involved in swallowing and chewing.
The two bellies of the digastric muscle are joined by an intermediate tendon. This tendon may be absent in some cases. The intermediate tendon is encircled by a U-shaped fibrous tissue sling, which attaches to the greater cornu of the hyoid bone. This sling acts as a pulley, allowing the intermediate tendon to slide anteriorly and posteriorly. The digastric muscle is involved in complex jaw actions such as speaking, swallowing, chewing, and breathing.
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Frequently asked questions
The digastric muscle is comprised of two parts, the anterior and posterior bellies, which have different innervations. The anterior belly is innervated by the nerve to mylohyoid muscle, a branch of the inferior alveolar nerve, while the posterior belly is innervated by the digastric branch of the facial nerve.
The digastric muscle has two bellies with different embryological origins. The anterior belly is derived from the first pharyngeal arch, while the posterior belly is derived from the mesoderm of the second pharyngeal arch.
The digastric muscle is involved in complex jaw actions such as speaking, swallowing, chewing, and breathing. The posterior belly is particularly important for swallowing and chewing.
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 are connected by an intermediate tendon, which attaches to the hyoid bone.
The anterior belly of the digastric muscle is supplied by the submental artery of the facial artery. The posterior belly receives its blood supply from the posterior auricular and occipital arteries.
