Several muscles are located in the head, each with a specific function. These include muscles responsible for facial expressions, chewing (mastication), eye movement, and tongue movement.
Muscles of Facial Expression
These muscles allow us to smile, frown, and make other facial expressions. They originate in the skull and insert into the skin of the face. Examples include:
- Occipitofrontalis: Raises eyebrows and wrinkles the forehead.
- Orbicularis oculi: Closes the eyelids.
- Orbicularis oris: Closes and protrudes the lips.
- Zygomaticus major and minor: Draw the corners of the mouth upward and outward (smiling).
- Buccinator: Compresses the cheeks (e.g., when blowing).
Muscles of Mastication
These muscles are crucial for chewing. They attach to the mandible (lower jaw) and skull, allowing us to open and close our mouths, as well as move the jaw from side to side. Examples include:
- Masseter: Elevates the mandible (closes the jaw).
- Temporalis: Elevates and retracts the mandible.
- Medial pterygoid: Elevates and protrudes the mandible.
- Lateral pterygoid: Depresses and protrudes the mandible, and allows for side-to-side movement.
Extraocular Muscles
These muscles control eye movement. They attach to the eyeball and allow us to look up, down, left, right, and rotate our eyes. There are six extraocular muscles:
- Superior rectus: Elevates the eye.
- Inferior rectus: Depresses the eye.
- Lateral rectus: Abducts (moves the eye away from the midline) the eye.
- Medial rectus: Adducts (moves the eye toward the midline) the eye.
- Superior oblique: Intorts (rotates the top of the eye toward the nose), depresses, and abducts the eye.
- Inferior oblique: Extorts (rotates the top of the eye away from the nose), elevates, and abducts the eye.
Tongue Muscles
The tongue is primarily composed of muscle and is essential for speech, swallowing, and taste. It contains both intrinsic and extrinsic muscles.
- Intrinsic tongue muscles: These muscles are located entirely within the tongue and are responsible for changing its shape. They include the superior longitudinal, inferior longitudinal, transverse, and vertical muscles.
- Extrinsic tongue muscles: These muscles originate outside the tongue and insert into it, controlling its position. They include the genioglossus, hyoglossus, styloglossus, and palatoglossus muscles.
In summary, the head contains a complex network of muscles vital for various functions, including facial expressions, chewing, eye movement, and tongue movement.
