Which muscle elevates the hyoid and assists in opening the mouth?

Which muscle elevates the hyoid and assists in opening the mouth?

• A. Geniohyoid
• B. Stylohyoid
• C. Sternohyoid
• D. Anterior Digastric

Answer: (A)

The key idea is how the suprahyoid muscles position the hyoid to enable mouth opening. The geniohyoid attaches from the inner surface of the mandible to the hyoid, so when it contracts it pulls the hyoid upward (elevates) and forward (anteriorly). This forward/upward movement of the hyoid helps set the floor of the mouth and reduces resistance as the mandible depresses to open the mouth. In this context, the geniohyoid’s action of elevating and moving the hyoid forward makes it the muscle most directly contributing to opening the mouth. The other options don’t fit as neatly: the sternohyoid depresses the hyoid, the stylohyoid elevates and retracts the hyoid, and while the anterior digastric can help depress the mandible to open the mouth, it doesn’t combine the same hyoid-elevating/anteriorly moving action that characterizes the geniohyoid in terms of facilitating mouth opening.

The key idea is how the suprahyoid muscles position the hyoid to enable mouth opening. The geniohyoid attaches from the inner surface of the mandible to the hyoid, so when it contracts it pulls the hyoid upward (elevates) and forward (anteriorly). This forward/upward movement of the hyoid helps set the floor of the mouth and reduces resistance as the mandible depresses to open the mouth. In this context, the geniohyoid’s action of elevating and moving the hyoid forward makes it the muscle most directly contributing to opening the mouth.

The other options don’t fit as neatly: the sternohyoid depresses the hyoid, the stylohyoid elevates and retracts the hyoid, and while the anterior digastric can help depress the mandible to open the mouth, it doesn’t combine the same hyoid-elevating/anteriorly moving action that characterizes the geniohyoid in terms of facilitating mouth opening.