Anatomy - Test 2 - Muscle Actions

The Nasalis Muscle is the correct answer because it is the muscle responsible for flaring the nostrils. It is located in the nose and consists of two parts, the transverse part and the alar part. When the transverse part contracts, it compresses the nostrils, while the alar part widens and flares the nostrils. This muscle is important for controlling airflow through the nasal passages and plays a role in facial expressions, particularly during expressions of disgust or anger.

The diaphragm is the primary muscle of respiration. When it contracts, it decreases the intrathoracic pressure and increases the intraabdominal pressure. This allows for inhalation by expanding the thoracic cavity and drawing air into the lungs. The diaphragm also plays a role in exhalation by relaxing and allowing the lungs to deflate. It is a dome-shaped muscle located at the base of the thoracic cavity, separating the chest from the abdomen.

The Buccinator Muscle is responsible for compressing the cheeks. This muscle is located in the face and forms the walls of the cheeks. When it contracts, it helps in actions such as blowing, whistling, and sucking. It also assists in keeping food between the teeth during chewing. Therefore, the Buccinator Muscle is the correct answer because it is specifically involved in the compression of the cheeks.

The deltoid muscle is responsible for the flexion, abduction, extension, medial rotation, and lateral rotation of the arm. The anterior part of the deltoid muscle performs flexion and medial rotation, while the lateral part performs abduction, and the posterior part performs extension and lateral rotation. Therefore, the deltoid muscle is the correct answer as it is involved in multiple movements of the arm.

The frontalis muscle is responsible for elevating the eyebrows and creasing the skin of the forehead. This muscle is located in the forehead region and is responsible for facial expressions such as surprise or worry. When the frontalis muscle contracts, it lifts the eyebrows and creates horizontal creases on the forehead. This action is important for nonverbal communication and conveying emotions.

The sternocleidomastoid muscle is responsible for the rotation of the head. It is a long muscle that runs from the sternum and clavicle to the mastoid process of the skull. When both sides of the muscle contract together, they flex the neck forward, while when only one side contracts, it rotates the head to the opposite side. This muscle is important for various movements of the head and neck, including turning the head to look to the side or tilting it to the shoulder.

The Orbicularis Oris Muscle is responsible for protruding and closing the lips, creating a "pucker" effect. It is a circular muscle that surrounds the mouth and is involved in various facial expressions, such as kissing, whistling, and speaking.

The internal intercostal muscle is responsible for decreasing the transverse dimensions of the ribs during exhalation. This muscle is located between the ribs and is part of the intercostal muscle group. When it contracts, it pulls the ribs downward and inward, reducing the space in the thoracic cavity and helping to expel air from the lungs during exhalation.

The external intercostal muscle and membrane are responsible for increasing the transverse dimensions of the ribs during inhalation. When we inhale, these muscles contract, pulling the ribs upward and outward. This action expands the chest cavity and allows for the intake of more air into the lungs.

The Platysma Muscle is responsible for elevating and creasing the skin of the neck, as well as depressing the lower lip or angle of the mouth. It is a thin, sheet-like muscle that covers the front of the neck and extends from the chest to the lower jaw. When contracted, it pulls the skin down, creating vertical wrinkles in the neck and causing the lower lip or angle of the mouth to droop.

The Pectoralis Major Muscle is responsible for adduction, medial rotation, and flexion of the arm. This means that it helps to bring the arm closer to the body, rotate it inward, and bend it at the shoulder joint. The other muscles listed in the options do not have these specific functions.

The trapezius muscle is responsible for the elevation of the scapula, which is commonly known as "shrugging the shoulders." When the trapezius muscle contracts, it pulls the scapula upward, causing the shoulders to rise. This muscle is located on the upper back and extends from the base of the skull to the middle of the back. It plays a crucial role in various movements of the shoulder and neck, including shrugging, rotating, and retracting the scapula.

The Latissimus Doris Muscle is responsible for adduction of the arm, extension of the arm, and medial rotation of the arm. It is a large muscle located in the back, extending from the upper arm to the lower back. When contracted, it pulls the arm towards the body, extends the arm backwards, and rotates the arm towards the midline of the body. This muscle is important for movements such as throwing, swimming, and rowing.

The serratus anterior muscle is responsible for the protraction of the scapula and holds the scapula against the thoracic wall. It is located on the lateral surface of the rib cage and attaches to the scapula. When the muscle contracts, it pulls the scapula forward and helps to stabilize it against the rib cage. This muscle is important for movements of the shoulder and arm, such as reaching and pushing.

The levator scapulae muscle is responsible for elevating and retracting the scapula, which is the shoulder blade. When someone "shrugs their shoulders," it means they are lifting and retracting their shoulder blades towards their ears. This movement is performed by the levator scapulae muscle. Therefore, the levator scapulae muscle is the correct answer for the given statement.

The Semispinalis Capitis Muscle is responsible for the extension of the head or unilateral rotation. It is located in the back of the neck and connects the vertebrae to the skull. When this muscle contracts, it helps to extend the head backward or rotate it to one side. This muscle is important for various movements of the head and neck, such as looking up at the ceiling or turning the head to the side.

The Occipitalis Muscle is responsible for moving the scalp backward and forward. It is a thin, flat muscle located at the back of the head. When contracted, it pulls the scalp backward, creating tension and allowing for movement. This muscle works in conjunction with other muscles in the scalp to control facial expressions and movements of the scalp.

The Pectoralis Minor Muscle is responsible for holding the scapula against the thoracic wall. It is a small, triangular muscle located underneath the Pectoralis Major Muscle. When contracted, it pulls the scapula downwards and forwards, helping to stabilize it against the rib cage. This muscle is important for movements of the shoulder and arm, as it helps to maintain proper alignment and function of the scapula.