Overview
The
suprahyoid muscles are a collection of four paired muscles, situated superior
to the hyoid bone. Their overall function is to elevate the hyoid and thus
widen the oesophagus, aiding in mastication & swallowing.
Gross Anatomy
From
superficial to deep: -
Stylohyoid |
|
Origin |
Styloid
process |
Insertion |
Greater
cornu of hyoid, superficial to digastric |
Nerve |
Facial
nerve (CN VII) before it enters the parotid gland |
Action |
Elevates
& retracts hyoid during swallowing |
Digastric |
|
Origin |
Ant. belly: digastric fossa on inner surface of mandible near midline Post. belly: base of mastoid |
Insertion |
Anterior and posterior bellies
meet to form an intermediate tendon which passes through a fibrous loop
anchored to the greater cornu of the hyoid |
Nerve |
Ant. belly: Mylohyoid (branch of Mandibular division of Trigeminal
nerve (CN Vc)) Post. belly: Facial nerve (CN VII) before it enters the parotid gland |
Action |
Can either elevate hyoid or, if
hyoid is fixed from below, depress mandible |
Mylohyoid |
|
Origin |
Mylohyoid
line along inner aspect of mandible |
Insertion |
Muscle on
each side slopes down toward one other, the fibres from the anterior ¾ of
each muscle interdigitating to form a midline raphe extending from chin to hyoid.
The posterior ¼ of each muscle inserts onto the superior aspect of the hyoid
body. |
Action |
A thin
sheet-like muscle, mylohyoid forms the floor of the mouth. Supports &
raises floor of mouth and elevates the hyoid. |
Nerve |
Mylohyoid
(branch of Mandibular division of Trigeminal nerve (CN Vc)) |
Geniohyoid |
|
Origin |
Inferior
mental spine (inner aspect of anterior mandible), deep to mylohyoid |
Insertion |
Upper
border of the hyoid body, deep to mylohyoid |
Action |
Elevates
& protracts hyoid or, if hyoid is fixed from below, depresses mandible |
Nerve |
C1 fibres
travelling with Hypoglossal nerve (CN XII) |