Chapter 10 - Section 10.2 - Muscles of the Head and Neck - Apply What You Know - Page 328: 1

Certainly! Intrinsic muscles of the head are typically muscles that are located within the head itself and are responsible for controlling fine movements of the head and face. Extrinsic muscles, on the other hand, are muscles that are located outside the head but are involved in moving or controlling the positioning of the head and its parts. Here are three intrinsic and three extrinsic muscles of the head: Intrinsic Muscles of the Head: 1. Temporalis Muscle: The temporalis muscle is an intrinsic muscle located on the side of the head, specifically in the temporal region. It is responsible for closing the jaw during chewing and is involved in the movement of the mandible (lower jaw). It is considered intrinsic because it is primarily confined within the head. 2. Frontalis Muscle: The frontalis muscle is an intrinsic muscle of the forehead. It is responsible for raising the eyebrows and creating forehead wrinkles. It controls the movement of the forehead skin and is intrinsic because it is situated entirely within the head region. 3. Orbicularis Oris Muscle: The orbicularis oris muscle is an intrinsic muscle encircling the mouth. It is responsible for controlling the shape and closure of the lips, aiding in various facial expressions and functions like speaking, eating, and kissing. This muscle is intrinsic because it is located entirely within the head. Extrinsic Muscles of the Head: 1. Sternocleidomastoid Muscle: The sternocleidomastoid muscle is an extrinsic muscle of the head and neck. It originates from the sternum (sterno-) and clavicle (cleido-) and inserts into the mastoid process of the temporal bone. This muscle is responsible for turning and tilting the head, flexing the neck, and is extrinsic because it spans from outside the head to the head and neck. 2. Trapezius Muscle: The trapezius muscle is another extrinsic muscle of the head and neck. It originates from the spine and the shoulder girdle and inserts into the scapula and clavicle. It plays a role in elevating and depressing the scapula and is extrinsic because it spans from outside the head and neck to these regions. 3. Digastric Muscle: The digastric muscle is an extrinsic muscle of the head and neck. It consists of two muscle bellies connected by an intermediate tendon. One belly originates from the digastric fossa of the mandible, and the other originates from the mastoid notch of the temporal bone. It is involved in various movements of the mandible and hyoid bone, making it extrinsic due to its connection to structures outside the head. These classifications are based on the location and primary functions of these muscles in the head and neck region. Intrinsic muscles are primarily responsible for fine movements within the head, while extrinsic muscles are involved in movements that extend beyond the head itself.

Certainly! Intrinsic muscles of the head are typically muscles that are located within the head itself and are responsible for controlling fine movements of the head and face. Extrinsic muscles, on the other hand, are muscles that are located outside the head but are involved in moving or controlling the positioning of the head and its parts. Here are three intrinsic and three extrinsic muscles of the head: Intrinsic Muscles of the Head: 1. Temporalis Muscle: The temporalis muscle is an intrinsic muscle located on the side of the head, specifically in the temporal region. It is responsible for closing the jaw during chewing and is involved in the movement of the mandible (lower jaw). It is considered intrinsic because it is primarily confined within the head. 2. Frontalis Muscle: The frontalis muscle is an intrinsic muscle of the forehead. It is responsible for raising the eyebrows and creating forehead wrinkles. It controls the movement of the forehead skin and is intrinsic because it is situated entirely within the head region. 3. Orbicularis Oris Muscle: The orbicularis oris muscle is an intrinsic muscle encircling the mouth. It is responsible for controlling the shape and closure of the lips, aiding in various facial expressions and functions like speaking, eating, and kissing. This muscle is intrinsic because it is located entirely within the head. Extrinsic Muscles of the Head: 1. Sternocleidomastoid Muscle: The sternocleidomastoid muscle is an extrinsic muscle of the head and neck. It originates from the sternum (sterno-) and clavicle (cleido-) and inserts into the mastoid process of the temporal bone. This muscle is responsible for turning and tilting the head, flexing the neck, and is extrinsic because it spans from outside the head to the head and neck. 2. Trapezius Muscle: The trapezius muscle is another extrinsic muscle of the head and neck. It originates from the spine and the shoulder girdle and inserts into the scapula and clavicle. It plays a role in elevating and depressing the scapula and is extrinsic because it spans from outside the head and neck to these regions. 3. Digastric Muscle: The digastric muscle is an extrinsic muscle of the head and neck. It consists of two muscle bellies connected by an intermediate tendon. One belly originates from the digastric fossa of the mandible, and the other originates from the mastoid notch of the temporal bone. It is involved in various movements of the mandible and hyoid bone, making it extrinsic due to its connection to structures outside the head. These classifications are based on the location and primary functions of these muscles in the head and neck region. Intrinsic muscles are primarily responsible for fine movements within the head, while extrinsic muscles are involved in movements that extend beyond the head itself.