Dominic Stone
The digastric muscle, also known as digastricus, is a bilaterally paired suprahyoid muscle located under the jaw. It consists of two muscular bellies, the anterior and posterior belly, which are united by an intermediate tendon. The digastric muscle is involved in various functions, including depressing the mandible, elevating the hyoid bone, and coordinating with other head and neck muscles during swallowing, chewing, and speech. Its specific attachment sites may vary among different species, such as in orangutans, where the posterior digastric attaches to the mandible instead of the hyoid bone.
| Characteristics | Values |
|---|---|
| Definition | A bilaterally paired suprahyoid muscle located under the jaw |
| Parts | Anterior belly and posterior belly |
| Origin of the name | Derived from the Greek word "dis" meaning double or twofold, and Latin "gaster" meaning belly |
| Function | Depresses the mandible, elevates the hyoid bone, coordinates with other head and neck muscles during swallowing, chewing, and speech |
| Innervation | The anterior belly is innervated by the inferior alveolar nerve, a branch of the mandibular nerve (CN V). The posterior belly is innervated by the digastric branch of the facial nerve (CN VII) |
| Blood supply | Vertebral artery and the deep descending branch of the occipital artery |
| Attachments | The anterior belly attaches to the digastric fossa of the mandible. The posterior belly attaches to the mastoid notch of the temporal bone |
| Variations | The anterior belly has more anatomical variations than the posterior belly, with unilateral variants being more common than bilateral variants |
| Palpation | Trigger points in the anterior belly are palpated with the neck extended and the head tilted back |
| Presence in animals | Present in a variety of animals, with specific attachment sites varying between species |
Explore related products
What You'll Learn
- The digastric muscle is a suprahyoid muscle of the neck
- It consists of two bellies, the anterior and posterior
- The two bellies are connected by an intermediate tendon
- The digastric muscle is involved in jaw opening, chewing, and speech
- It is a critical landmark in neck dissections and neck reconstruction procedures
The digastric muscle is a suprahyoid muscle of the neck
The digastric muscle has two muscular bellies: the anterior belly and the posterior belly. The anterior belly is derived from the first brachial arch, while the posterior belly is derived from the second brachial arch. Consequently, the two bellies differ in their innervation. The anterior belly is innervated by the mandibular nerve (CN V), while the posterior belly is innervated by the facial nerve (CN VII). The anterior belly is also associated with the trigeminal nerve, and the posterior belly with the trigeminal motor nucleus.
The anterior belly of the digastric muscle originates from the digastric fossa of the mandible, near the midline. The posterior belly originates from the mastoid notch of the temporal bone. The two bellies are united by an intermediate tendon, which attaches to the hyoid bone. The intermediate tendon may not always be present, and in some individuals, it may attach to the hyoid bone medially or laterally. The anterior belly may also be double or absent altogether, and the posterior belly may arise partly or entirely from the styloid process of the temporal bone.
The digastric muscle is involved in several important functions, including depressing the mandible, elevating the hyoid bone, and coordinating with other head and neck muscles during swallowing, chewing, and speech. It also plays a role in protecting the airway during swallowing and raising the tongue base. The digastric muscle is a significant surgical landmark in neck dissections and is valuable for neck reconstruction procedures.
Striated Muscle Elasticity: Fact or Fiction?
You may want to see also
Explore related products
It consists of two bellies, the anterior and posterior
The digastric muscle is a suprahyoid muscle located under the jaw. It consists of two bellies, the anterior and posterior, which are united by an intermediate tendon. The tendon attaches to the hyoid bone via a fibrous sling. 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 gets its name from the Latin word "gaster", meaning belly, and the Greek word "dis", meaning double or twofold, referring to its two-bellied structure.
The anterior belly of the digastric muscle originates from the digastric fossa of the mandible, near the midline. It attaches superiorly near the base of the mandible and runs inferiorly toward the hyoid bone. The anterior belly is involved in depressing the mandible and elevating the hyoid bone. It also plays a role in swallowing, chewing, and speech by coordinating with other head and neck muscles. The anterior belly is associated with the trigeminal nerve, receiving innervation from the mandibular nerve or, in some cases, both the mandibular and facial nerves.
The posterior belly of the digastric muscle originates from the mastoid notch of the temporal bone. It attaches superiorly to the temporal bone and slopes downward to meet the intermediate tendon. The posterior belly is involved in depressing the mandible and elevating the hyoid bone, along with the anterior belly. It also aids in head extension during movements. The posterior belly is associated with the facial nerve, receiving innervation from its branch.
The two bellies of the digastric muscle have distinct embryological origins, with the anterior belly arising from the first brachial arch and the posterior belly from the second brachial arch. This results in variations in their innervation and anatomical structure. The digastric muscle is an important landmark during neck surgeries and plays a valuable role in neck reconstruction procedures.
Unlocking Soleus Muscle Flexibility: Techniques for Shortening and Stretching
You may want to see also
Explore related products
The two bellies are connected by an intermediate tendon
The digastric muscle is a suprahyoid muscle located under the jaw. It consists of two bellies: the anterior belly and the posterior belly. The two bellies are united by an intermediate tendon, which attaches to the hyoid bone. The hyoid bone is a small, U-shaped bone located in the anterior neck, just above the thyroid cartilage. The intermediate tendon is held in a loop that attaches to the hyoid bone. This loop is formed by a U-shaped fibrous tissue sling, which 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, near the midline. It is innervated by the mandibular nerve (CN V) and can refer pain to the lower central incisors and the alveolar ridge. The posterior belly of the digastric muscle originates from the mastoid notch of the temporal bone. It is innervated by the facial nerve (CN VII) and may refer pain to the throat under the chin.
The two bellies of the digastric muscle have different embryological origins. The anterior belly is derived from the first brachial arch, while the posterior belly is derived from the second brachial arch. Consequently, they are supplied by different nerves and arteries. The anterior belly is innervated by the mandibular nerve (CN V), while the posterior belly is innervated by the facial nerve (CN VII). The posterior belly may also be innervated by the spinal accessory nerve, which exits the skull through the jugular foramen.
The digastric muscle is involved in several important functions, including depressing the mandible and elevating the hyoid bone. It also coordinates with other head and neck muscles during swallowing, chewing, and speech. The anterior belly of the digastric muscle is one of three suprahyoid muscles that stabilize the hyoid bone during swallowing, which helps to protect the airway while eating.
Testosterone and Muscle Growth: What's the Real Connection?
You may want to see also
Explore related products
The digastric muscle is involved in jaw opening, chewing, and speech
The digastric muscle, also known as digastricus, is a bilaterally paired suprahyoid muscle located under the jaw. It is comprised of two parts: the anterior belly and the posterior belly, 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 composition of this muscle, which consists of two muscular bellies.
The anterior belly of the digastric muscle originates from the digastric fossa of the mandible, near the midline. It is innervated by the inferior alveolar nerve, a branch of the mandibular nerve (CN V), which is derived from the trigeminal nerve. The trigeminal motor nucleus innervates the anterior belly of the digastric muscle, along with other jaw-opener/closer muscles. The anterior belly is also occasionally innervated by the facial nerve (CN VII) and the mylohyoid nerve.
The posterior belly of the digastric muscle originates from the mastoid notch of the temporal bone. It is innervated by the digastric branch of the facial nerve (CN VII). The facial nucleus innervates the posterior belly, along with other jaw-opener/closer muscles. The posterior belly is located posterior to the parotid gland and runs downward, lying medial to the gland.
Understanding Muscle Tears: Causes, Treatment, and Prevention
You may want to see also
Explore related products
It is a critical landmark in neck dissections and neck reconstruction procedures
The digastric muscle is a critical landmark in neck dissections and neck reconstruction procedures. It is a small but important muscle in the neck, with a variety of functions, including depressing the mandible and elevating the hyoid bone.
The digastric muscle consists of two muscular bellies, the anterior and posterior belly, which are connected by an intermediate tendon. The posterior belly is attached to the mastoid notch of the temporal bone, while the anterior belly is attached to the digastric fossa of the mandible. The intermediate tendon is then attached to the hyoid bone. This muscle divides the anterior triangle of the neck into four smaller triangles: the submandibular triangle (digastric triangle), the carotid triangle, the submental triangle (suprahyoid triangle), and the inferior carotid triangle (muscular triangle).
The digastric muscle is a significant surgical landmark in neck dissections, and the posterior belly, in particular, can help identify several important structures, including the spinal accessory and hypoglossal nerves, internal jugular veins, and carotid arteries. The anterior belly also has important anatomical variations, with unilateral variants being more common than bilateral variants. These variations can be misleading in imaging studies, so careful consideration is necessary during clinical assessment and surgical planning.
Furthermore, the digastric muscle is involved in coordinating with other head and neck muscles during swallowing, chewing, and speech. It helps to raise the tongue base and hyoid bone and depress the mandible for jaw opening, making it an essential muscle for normal speaking and eating functions.
Overall, the digastric muscle plays a crucial role in neck anatomy and function, making it an important landmark and consideration in neck dissections and reconstruction procedures.
The Role and Function of the Cremaster Muscle
You may want to see also
Frequently asked questions
The digastric muscle is a small but important suprahyoid muscle in the neck. It is comprised of two parts: the anterior and posterior bellies, which are united by an intermediate tendon.
The digastric muscle assists in mandible movement, including mandible depression and hyoid bone elevation. It also divides the anterior triangle of the neck into four smaller triangles: the submandibular triangle, the carotid triangle, the submental triangle, and the inferior carotid triangle.
The digastric muscle can be located by palpating the trigger points in the anterior and posterior bellies. To locate the anterior belly, the patient is asked to swallow, and the prominence of the belly can be felt under the thumb tips as the hyoid is drawn superiorly. To locate the posterior belly, pressure is applied between the angle of the jaw and the mastoid process.
