Digastric muscle
Digastric muscle | |
---|---|
temporalis are relaxed. | |
Identifiers | |
Latin | musculus digastricus |
TA98 | A04.2.03.002 |
TA2 | 2160 |
FMA | 46291 |
Anatomical terms of muscle] |
The digastric muscle (also digastricus) (named digastric as it has two 'bellies') is a bilaterally paired
The term "digastric muscle" refers to this specific muscle even though there are other muscles in the body to feature two bellies.[citation needed]
Anatomy
The digastric muscle consists of two muscular bellies united by an intermediate tendon. The posterior belly is 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 consequently differ in their innervation (the former being innervated via CN V and the latter via CN VII).[1]
Structure
Posterior belly
The posterior belly attaches at the
It extends anteroinferiorly from its osseous attachment toward the intermediate tendon.[1]
Anterior belly
The anterior belly attaches at the
It extends inferoposteriorly from its origin toward the intermediate tendon.[1]
Intermediate tendon
The two bellies meet at the intermediate
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.[citation needed]
Relations
The posterior belly is situated posterior to the parotid gland[2] and the facial nerve.[citation needed]
Triangles of the neck
The digastric muscle divides the
Variation
The intermediate tendon may be absent. The posterior belly may arise partly (by an supplemental strip of muscle) or entirely from the styloid process of the temporal bone.
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.[citation needed] It may fuse with the mylohyoid muscle.[1]
The tendon may pass in front, more rarely behind the stylohyoideus. The mentohyoideus muscle passes from the body of hyoid bone to chin.[citation needed]
Actions/movements
The muscle depresses the mandible, and may elevate the hyoid bone.[1]
It depresses the
Function
The digastric muscle is involved in any complex jaw action such as speaking, swallowing, chewing, and breathing.[citation needed] The posterior belly is particularly functionally involved in swallowing and chewing.[1]
Other animals
The digastric muscles are present in a variety of animals, specific attachment sites may vary. For example, in the orangutan, the posterior digastric attaches to the mandible rather than the hyoid.[citation needed]
References
This article incorporates text in the public domain from page 391 of the 20th edition of Gray's Anatomy (1918)
- ^ OCLC 1201341621.)
{{cite book}}
: CS1 maint: location missing publisher (link - ISBN 978-0-323-40066-4, retrieved 2020-11-10
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.