The digastric muscle Pain, commonly referred to by its two muscular bellies, opens the jaw. Its tendrils connect directly to the hyoid bone where it attaches.
These muscles are innervated by two branches of facial nerve and one branch of inferior alveolar nerve; respectively. A fibrous tissue sling acts as a pulley system to allow both bellies to move freely.
Anterior Belly
The digastric muscle (also referred to as suprahyoid muscles) are two muscular bellies found in the neck region. Each digastric muscle comprises two anterior and posterior bellies connected by an intermediate tendon that attaches onto both the body and greater cornu of the hyoid bone; in some cadaveric specimens this tendon penetrates stylohyoid muscle as well. Anterior bellies of digastric muscles originate at their respective fossas at base of mandible; when contracted these anterior bellies depress and elevate this bone simultaneously when contracted compared with its peers.
The posterior belly of the digastric muscle is attached to the hyoid bone via a fibrous sling made up of part of submental lymph nodes and fibers, while it is innervated by facial nerve VII.
Flexing of the digastric muscle causes it to contract and raise up the hyoid bone while depressing the lower jaw. The muscle is essential in the functioning of cervical spine articular function and may be at play in neck pain caused by poor posture or trauma; for instance, prolonged cervical protraction (head pushing forward) may cause the digastric muscle to exert posterior force against lower jaw which can result in pain and/or swelling of retrodiscal tissue.
The carotid triangle is a paired triangle bordered on three sides by posterior belly of digastric muscle; medially by superior belly of omohyoid muscle; and laterally by sternocleidomastoid muscle. Within its boundaries lie common carotid artery, internal and external carotid arteries, submandibular gland and jugular vein.
Posterior Belly
If you’re experiencing jaw pain and difficulty swallowing, the digastric muscle could be to blame. It is a small but thin muscle located on the side of your neck just under and behind the hyoid bone and responsible for elevating its position, retracting four lower incisor teeth as well as opening your mouth – it is innervated by mylohyoid nerve, trigeminal nerve (cranial nerve V), and facial nerve (cranial nerve VII).
The digastric muscle has two bellies: anterior and posterior. This muscle connects with the hyoid bone via an intermediate tendon sling that’s innervated by mylohyoid and facial nerve, with its posterior belly passing deep to attach into stylohyoid muscle before penetrating greater cornu of hyoid bone for attachment.
Sometimes found at the digastric fossa and inserting into the ipsilateral intermediate tendon is an accessory anterior belly which begins in the digastric fossa and runs as far as to serve the muscles associated with mylohyoid muscle, and partially served by inferior alveolar nerve which originates in first pharyngeal arch. These muscles are served by trigeminal nerve via mylohyoid muscle as well as some part of inferior alveolar nerve which originates in first pharyngeal arch to feed these muscles.
Additionally to its primary function of raising the hyoid, this muscle also assists in opening and closing mouth, as well as acting as an involuntary chewing muscle. Unfortunately, however, the muscle can be subjected to trauma from accidents involving either head or neck trauma as well as repetitive strain injuries from strain on jawbone.
Trigger points can occur anywhere on a muscle, including upper portions of the sternocleidomastoid muscle (SCM). Trigger points can cause SCM pain as well as neck and jaw discomfort; SCM trigger points may often be felt under the chin or in the back of the neck, with pain radiating into hyoid bone areas and even into occiput (back of skull). Postdigastric muscles are particularly prone to trigger points which can be palpated by holding jaw closed with fingers; after pressing down you can run your fingers along SCM’s front border toward earlobe to feel for tender spots in SCM where muscles connect — especially around its front border towards its front border towards its front border towards its front border where very tender spots exist.
Intermediate Tendon
The digastric muscle is composed of two bellies connected by an intermediate tendon and part of the suprahyoid muscles, involved in chewing and swallowing. It protrudes the jaw forward while its posterior belly depresses it; both bellies are innervated by mylohyoid nerve.
The intermediate tendon is enclosed by a fibrous tissue sling that functions like a pulley and allows muscle movement through it freely. Attached to the body of the hyoid bone and often penetrating stylohyoid muscle, its attachment points include stylohyoid muscle. Innervations for its anterior belly include mylohyoid and facial nerves while its posterior belly receives innervations from mylohyoid, vagus and pharyngeal nerves respectively.
Pain in the digastric muscle may result from several conditions, including sprains and strains, dental issues, neck trauma, teeth grinding and tension in the jaw. Myopathy – a disease which weakens and painfully affects muscle cells – often occurs among older individuals and should be considered an occupational risk.
Myopathy causes intense discomfort while eating or chewing. Patients may notice they cannot open their mouth as wide before or are having difficulty swallowing, among other issues. There are exercises which can strengthen and improve digastric muscle function – one being practicing jaw protrusion exercises which involve pushing forward against resistance with lower jaw push forward ten repetitions per session three times daily.
One exercise to strengthen the digastric muscle is placing both thumbs underneath the chin and pushing upward with resistance against them, repeated ten times daily. Another is to clench jaw repeatedly; repeat this action ten times each day too for maximum benefit. By repeating these exercises daily, patients can increase their ability to use digastric muscles without experiencing pain or other adverse symptoms; it is advised that all such exercises be conducted under medical supervision.
Trigger Points
Trigger points are hypersensitive knots of tight muscle fibers that form in taut bands of skeletal muscle and are commonly associated with myofascial pain syndrome. They are painful to palpate and may radiate discomfort into other parts of the body through “referred pain”, leading to headaches, neck ache and jaw ache – as well as headaches for some people! Muscle pain from trigger points usually goes away over time but persistent symptoms should always be evaluated by health professionals as this could signal deeper problems.
The digastric muscle has two muscular bellies: the anterior belly and posterior belly. They connect via a common tendon below to the hyoid bone; respectively, these bellies depress and retract it while raising or lowering its position; conversely, its posterior bellies elevate or lower it respectively.
Any force that rapidly flexes or extends the cervical spine, or that repeatedly snaps back the head forward and backward, overloads this muscle. Prolonged holding of posture or breathing through mouth for prolonged periods also can put undue strain on this muscle and overloads its many thousands of fibres until they bunch together into a nodule or knot – known as a trigger point – until they’re exercised again.
Trigger points cause pain throughout the body when activated; most often this manifests itself in the upper throat, nose and face areas as well as lower four central teeth or the area surrounding the tongue. Massage and trigger point injection are two effective means of disarming trigger points.
Self-release techniques for the digastric muscle include applying gentle pressure with a supported thumb contact or employing micro-stripping release techniques. Massage involves applying sustained, gradual pressure over an area near a trigger point for four to eight seconds before gradually releasing it over time, relieving tension and decreasing sensitivity of pressure receptors in muscles. While micro-stripping release techniques use a stripping motion over trigger points in order to induce localized twitch responses that release tension quickly.
