Medicine:Digastric muscle
| Digastric muscle | |
|---|---|
 Muscles of the neck. Lateral view. | |
 Front view of neck. | |
| Details | |
| Origin | Anterior belly - digastric fossa (mandible); posterior belly - mastoid notch of temporal bone |
| Insertion | Intermediate tendon (hyoid bone) |
| Artery | Anterior belly - Submental branch of facial artery; posterior belly - occipital artery |
| Nerve | Anterior belly - mandibular division (V3) of the trigeminal (CN V) via the mylohyoid nerve; posterior belly - facial nerve (CN VII) |
| Actions | Opens the jaw when the masseter and the temporalis are relaxed. |
| Identifiers | |
| Latin | musculus digastricus or musculus biventer mandibulae |
| Anatomical terms of muscle | |
The digastric muscle (also digastricus or musculus biventer mandibulae) (named digastric as it has two 'bellies') is a bilaterally paired suprahyoid muscle located under the jaw. Its posterior belly is attached to the mastoid notch of temporal bone, and its anterior belly is attached to the digastric fossa of mandible; the two bellies are united by an intermediate tendon which is held in a loop that attaches to the hyoid bone. The anterior belly is innervated via the mandibular nerve (cranial nerve V), and the posterior belly is innervated via the facial nerve (cranial nerve VII). It may act to depress the mandible or elevate the hyoid bone.
Anatomy
The digastric muscle consists of two muscular bellies united by an intermediate tendon with the posterior belly longer than the anterior belly. The two bellies of the digastric muscle have different embryological origins - the anterior belly is derived from the first brachial arch and the posterior belly from the second brachial arch and thus differ in their innervation.[1]
Structure
Posterior belly
The posterior belly attaches at the mastoid notch of the temporal bone[1] (which is located upon the inferior surface of the skull, medial to the mastoid process of the temporal bone - between the mastoid process and the styloid process of the temporal bone).[2]
It extends antero-inferiorly from its osseous attachment toward the intermediate tendon.[1]
Anterior belly
The anterior belly attaches at the digastric fossa of mandible (situated at the base of the mandible near the midline).[1]
It extends postero-inferiorly from its origin toward the intermediate tendon.[1]
Intermediate tendon
The two bellies meet at the intermediate tendon which perforates the stylohyoideus muscle. The tendon is embraced by a fibrous sling which attaches the body and greater cornu of hyoid bone. The tendon occasionally features a synovial sheath.[1]
Innervation
The anterior belly 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 (CN V3)).[1]
The posterior belly is supplied by the digastric branch of facial nerve.[3]
Relations
The posterior belly is situated posterior to the parotid gland[4] while the anterior belly is closer to the sub-mandibular salivary gland which is a content of the digastric triangle.[5]
Triangles of the neck
The digastric 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).
Variation
The anterior belly may be double, or extra slips from this belly may pass to the jaw or mylohyoideus or decussate with a similar slip on opposite side. It may be absent and posterior belly inserted into the middle of the jaw or hyoid bone. It may fuse with the mylohyoid muscle.[1]
Actions/movements
The muscle depresses the mandible, and may elevate the hyoid bone.[1]
Function
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.[1]
Other animals
References
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Standring, Susan (2020). Gray's Anatomy: The Anatomical Basis of Clinical Practice (42nd ed.). New York. pp. 581. ISBN 978-0-7020-7707-4. OCLC 1201341621.
- ↑ "Digastric: Origin, Insertion, Action & Nerve Supply » How To Relief" (in en-US). https://www.howtorelief.com/digastric-origin-insertion-action-nerve-supply/.
- ↑ "Posterior Belly of Digastric Muscle | Complete Anatomy" (in en-us). https://www.elsevier.com/resources/anatomy/muscular-system/muscles-of-neck/posterior-belly-of-digastric-muscle/24813.
- ↑ Schiraldi, Michael; Baron, Eli M.; Vaccaro, Alexander R. (2018-01-01), Baron, Eli M.; Vaccaro, Alexander R., eds., "Procedure 5 - Anterior C1-C2 Arthrodesis: Lateral Approach of Barbour and Whitesides" (in en), Operative Techniques: Spine Surgery (Third Edition), Operative Techniques (Philadelphia: Elsevier): pp. 36–40, doi:10.1016/b978-0-323-40066-4.00005-9, ISBN 978-0-323-40066-4, http://www.sciencedirect.com/science/article/pii/B9780323400664000059, retrieved 2020-11-10
- ↑ "Submandibular triangle" (in en). https://www.kenhub.com/en/library/anatomy/submandibular-triangle.
External links
- Frontal section
- Anatomy figure: 34:02-02 at Human Anatomy Online, SUNY Downstate Medical Center
- Anatomy photo:24:17-0101 at the SUNY Downstate Medical Center
- "Anatomy diagram: 25420.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2015-02-26. https://web.archive.org/web/20150226040726/http://www.tk.de/rochelexikon/pics/s25420.000-1.html.
 |  |
