Muscles Of Mastication

The digastric muscle is indeed a sling-like muscle that has an anterior and posterior belly. This muscle is located in the neck and plays a role in various functions such as swallowing and opening the mouth. The anterior belly is attached to the mandible while the posterior belly is attached to the hyoid bone. Together, they work to control the movement of the jaw and aid in the processes of chewing and speaking.

backward

The statement is true because the sternocleidomastoid muscle (SCM) does indeed insert into the mastoid process of the temporal bone. The SCM is a large muscle located in the neck that originates from the sternum and clavicle and inserts into the mastoid process. It plays a crucial role in various movements of the head and neck, such as rotating the head to the opposite side and flexing the neck.

The hyoid bone is a unique bone in the human body that is not directly connected to any other bone. It is suspended in the neck by a network of muscles and ligaments, which allow it to move and function in various ways, including in the support of the tongue and the muscles involved in swallowing and speech. So, while it is not connected to other bones by joints, it is indirectly connected to other structures in the neck and plays an important role in the functioning of the throat and voice box.

The lateral pterygoid muscle does not elevate the mandible to close the mouth. The masseter, temporal, and medial pterygoid muscles are responsible for the elevation of the mandible, while the lateral pterygoid muscle mainly helps in the lateral movement of the mandible.

lateral

The statement is true. The infrahyoid muscles, which include the sternohyoid, omohyoid, thyrohyoid, and sternothyroid muscles, are all innervated by cervical nerves. These muscles are located below the hyoid bone and are responsible for depressing the hyoid bone and larynx during swallowing and speaking. The cervical nerves, specifically the ansa cervicalis and the branches of the cervical plexus, provide the motor innervation to these muscles. Therefore, the statement is correct.

The temporalis muscle is indeed one of the muscles of mastication, but it is not the only muscle responsible for retruding or retracting the mandible (lower jaw). The primary muscle responsible for mandibular retrusion is the digastric muscle, specifically the posterior belly of the digastric muscle. The temporalis muscle primarily elevates and retracts the mandible but is not the sole muscle involved in mandibular retrusion.

The sternothyroid muscle does not originate on the thyroid and does not insert on the sternum. It actually originates on the posterior surface of the manubrium of the sternum and inserts on the oblique line of the thyroid cartilage. Therefore, the statement is false.

trapezius

The medial pterygoid muscle takes a small part of its origin from the maxillary tuberosity. The maxillary tuberosity is a bony prominence located on the maxilla, which is the upper jawbone. The medial pterygoid muscle is one of the muscles involved in chewing and is attached to the inner surface of the mandible (lower jawbone) and the pterygoid plates of the sphenoid bone. It helps in the elevation and lateral movement of the mandible during chewing.

The lateral pterygoid muscle has fibers that primarily run horizontally. This muscle is located in the jaw and plays a crucial role in the movement of the mandible. It helps in opening and closing the mouth, as well as in moving the jaw from side to side. The horizontal orientation of its fibers allows for these specific movements and contributes to the overall function of the muscle.

The correct answer is thyrohyoid. The geniohyoid, stylohyoid, and digastric muscles are all examples of superhyoid muscles. These muscles are located above the hyoid bone and are involved in various functions such as swallowing and elevating the hyoid bone during speech and swallowing. However, the thyrohyoid muscle is not considered a superhyoid muscle. It is located below the hyoid bone and connects the thyroid cartilage to the hyoid bone. Its primary function is to help in the movement of the larynx during swallowing and speaking.

All of the muscles listed in the question aid in pulling down on the hyoid bone. The omohyoid muscle, sternohyoid muscle, sterno thyroid muscle, and thyrohyoid muscle all contribute to the movement of pulling down on the hyoid bone. Therefore, the correct answer is that all of them aid in pulling down on the hyoid bone.

All of the muscles listed in the options have more than one origin. The masseter muscle has two origins, the zygomatic arch and the maxilla. The medial pterygoid muscle has two origins, the medial surface of the lateral pterygoid plate and the tuberosity of the maxilla. The lateral pterygoid muscle also has two origins, the superior head from the infratemporal surface of the greater wing of the sphenoid bone and the inferior head from the lateral surface of the lateral pterygoid plate. Therefore, the correct answer is all of the above.

thyrohyoid