The masseter muscle plays a key role in elevating the mandible during chewing, making it essential for mastication. Its thick, powerful structure is designed to generate significant force.

The sternocleidomastoid muscle helps rotate the head and flex the neck. Its action is fundamental for head movement and positioning.

The digastric muscle plays a role in depressing the mandible, thereby assisting in opening the mouth. It is one of the suprahyoid muscles that help in initiating the process of jaw lowering during opening.

The orbicularis oculi muscle encircles the eye and is crucial for closing the eyelids. It plays a significant role in blinking and protecting the eye.

The orbicularis oris muscle encircles the mouth and is responsible for puckering the lips. Its contraction enables lip movements essential for speech and facial expressions.

The temporalis muscle is located in the temporal fossa and plays a significant role in elevating and retracting the mandible. Its fan-shaped structure permits effective force generation during mastication.

The lateral pterygoid muscle is responsible for protruding the mandible as well as aiding in lateral deviations during chewing. Its specialized action facilitates coordinated jaw movements during mastication.

The mylohyoid muscle is part of the suprahyoid group and contributes to forming the floor of the mouth. It also assists in elevating the hyoid bone during swallowing and speech.

The digastric muscle assists in depressing the mandible, thereby facilitating mouth opening. As a member of the suprahyoid group, it plays a crucial role in various oral functions.

The masseter muscle is one of the strongest masticatory muscles, essential for biting and chewing. Its powerful contraction provides the force necessary for breaking down food effectively.

The frontalis muscle is responsible for lifting the eyebrows and wrinkling the forehead. Its contraction is a key contributor to facial expressions that indicate surprise or curiosity.

The platysma is a superficial muscle in the neck that affects facial expressions by stretching the skin. Despite its thin appearance, it contributes to subtle movements in the lower face and neck region.

The levator veli palatini muscle is responsible for elevating the soft palate during swallowing, preventing food from entering the nasal cavity. Its proper function is essential for clear speech and safe swallowing.

The zygomaticus major muscle originates from the zygomatic bone and is crucial for elevating the corners of the mouth, thereby contributing significantly to smiling. Its contraction pulls the lip upward and laterally.

The auricularis muscle group is primarily involved in moving the ear, although its role is limited in humans compared to other mammals. Its vestigial function underscores the evolutionary changes within human facial musculature.

The masseter muscle is innervated by the mandibular branch (V3) of the trigeminal nerve. Damage to this nerve branch can directly compromise the muscle's ability to elevate the mandible during mastication.

The levator veli palatini muscle is primarily responsible for elevating the soft palate during swallowing and speech. Its dysfunction leads to inadequate soft palate elevation, affecting both speech and swallowing.

The accessory nerve (CN XI) provides motor innervation to the sternocleidomastoid muscle. Injury to this nerve during surgery can significantly impair neck motion and head rotation.

The digastric muscle has a unique dual innervation: its anterior belly is supplied by a branch of the trigeminal nerve (CN V3), while its posterior belly is innervated by the facial nerve (CN VII). This dual innervation contributes to its role in mandibular depression and distinguishes it from other muscles.

The medial pterygoid muscle works synergistically with the masseter to elevate the mandible, particularly during the grinding phase of mastication. Its effective contraction ensures proper occlusion and efficient chewing.