Table of Contents
- How Many Muscles Are in the Face?
- What Muscles Are in the Neck?
- How Many Muscles Are in the Back?
- Lesson Summary
When studying the anatomy of the face, it is interesting to know that there are 43 muscles located in the face and head region. These muscles often work together to perform a variety of facial expressions and movements of the eyes, lips, and cheeks. There are varying opinions on exactly how many muscles are involved in smiling versus frowning, but most agree that it takes more muscles to frown than to smile. Like all regions of the body, there are superficial muscles and muscles that are located underneath, known as deep muscles. The table shown will highlight some of the prominent muscles of the face, their locations, and actions.
|Frontalis||over the frontal bone, on the forehead||raises the eyebrows|
|Temporalis||over the temporalis bone, on the side of the head||aids in chewing|
|Orbicularis Oculi||encircles the eyes||controls blinking, squinting|
|Zygomaticus Major and Minor||from the mouth to the zygomatic bone||draws the lips up and to the sides|
|Orbicularis Oris||encircles the mouth||movements of the lips such as puckering, pouting, whistling|
|Buccinator||lies in the space between the mandible and maxillae||controls cheek movements when chewing, whistling, or blowing|
|Masseter||runs between the zygomatic bone and mandible||jaw movements for chewing|
Some of the muscles of the neck also have a role in the movements of the head and face. There are over 20 muscles found in the neck region. When studying the anatomy of the neck, it is best to work through them in groups by location: anterior, lateral, and posterior. The table shown will highlight some of the muscles of the neck.
|Anterior Neck Muscles||Origin/Insertion||Action|
|Platysma||skin below the clavicle to the mandible and skin around and below the mouth||frowning expression|
|Sternocleidomastoid||clavicle and sternum to the mastoid process||rotates, flexes, and laterally flexes the neck|
|Lateral Neck Muscles||Origin/Insertion||Action|
|Scalenes||transverse processes of cervical vertebrae to first rib||lateral flexion of the neck|
|Posterior Neck Muscles||Origin/Insertion||Action|
|Trapezius (Superficial)||from the base of the occipital bone to the clavicle and down to T12 vertebrae||extends the neck|
|Splenius Capitis (deep)||lateral occipital bone and mastoid process to cervical vertebrae||extends and laterally flexes the neck|
|Splenius Cervicis (deep)||spinous processes of cervical vertebrae to transverse processes of thoracic vertebrae||extends and laterally flexes the neck|
|Levator Scapulae (deep)||transverse processes of cervical vertebrae to scapula||raises the scapula and assists with lateral flexion of the neck|
There are deep muscles in the anterior part of the neck that assist with swallowing and talking. The suprahyoid muscle group and infrahyoid muscle group are muscles that act on the hyoid bone and larynx. These muscles act to raise or lower the hyoid bone, which is a small u-shaped bone deep in the neck. This is important to aid in swallowing. Some of these deep muscle groups also act on the larynx, where the voice box is located.
There are 40 muscles of the back that function to extend the vertebrae as well as rotate and laterally flex. Some of these muscles act on the arm or scapula, but they are located in the back. These muscles can be divided into axial and appendicular groups. Axial muscles will act only on the spine, whereas the appendicular muscles will act on the scapula and humerus.
The muscles in the back can also be divided into superficial, intermediate, and deep groups. The table shown will highlight some of the muscles found in the back.
|Appendicular Muscles of the Back||Location||Action|
|Trapezius||a large, superficial, diamond-shaped muscle that runs from the base of the skull to the scapula and clavicle and down to the 12th thoracic vertebrae||moves the scapula upward (as well as extend the spine)|
|Levator Scapulae||deep to the trapezius, from cervical vertebrae to the scapula||pulls the scapula upward when raising the arm and assists with lateral flexion of the neck|
|Latissimus Dorsi||a large, superficial muscle that originates on the thoracic and lumbar vertebrae and inserts on the humerus||pulls the arms backward|
|Rhomboids||deep to the trapezius, runs from the thoracic vertebrae to the medial border of the scapula||pulls the scapula toward the midline (retraction)|
|Serratus Anterior||deep and oblique muscles that run from the ribs to the scapula||act on the scapula to keep it in place as well as pull the scapula laterally|
|Axial Muscles of the Back||Location||Action|
|Erector Spinae Group||a set of 9 muscles in three groups (spinalis, thoracic, iliocostalis) that run along the entire vertebral column||extends, rotates, and laterally flexes the spine|
|Multifidus||the deepest and longest muscle that runs the length of the spine||extends the spine|
How many muscles are in the face? Forty-three, to be exact. These muscles of the face can often be remembered by the bones they are covering. It takes more muscles to frown than to smile, but both expressions use multiple muscles. Some muscles work on the mouth, such as the buccinator and pterygoid. Other muscles work on chewing, such as the masseter and temporalis. There are two orbicularis muscles, which are circular muscles. The orbicularis oris surrounds the lips, and the orbicularis oculi surround each eye.
The anatomy of the neck muscles can be grouped by location: anterior, posterior, and lateral. The anterior muscles of the neck tend to originate from the clavicle, such as with the sternocleidomastoid. This same muscle is responsible for helping to turn the head from side to side as it pulls on the mastoid process of the temporal bone toward the clavicle. The platysma is located on the anterior side of the neck, but it works on the jaw and facial skin. The posterior muscles of the neck are largely involved with extending or "holding up" the head. The splenius muscles are examples of neck extenders. There are also lateral muscles in the neck which include the scalenes. These muscles aid in lateral flexion of the neck.
There are 20 muscles of the back. These muscles are divided into appendicular and axial groups. The appendicular muscles work on the scapula and arm. The axial group of muscles acts on the vertebrae. Muscles such as the levator scapulae, rhomboids, and serratus anterior all work on the scapula, which is important for having good posture when sitting or standing up straight. The largest of the appendicular muscles is the latissimus dorsi which inserts on the humerus bone. The axial muscles such as the erector spinae group and multifidus run along the spine, acting on the vertebrae to extend, rotate, and laterally flex the spine.
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Because of the overlap of small muscles, the answer to this can vary. However, anatomists estimate that there are approximately 43 muscles in the face and 20 muscles in the neck.
The muscles of the face are specifically called craniofacial muscles. This is because some muscles are located on bones that form the cranium. For example, the frontalis and temporalis, and most of the facial muscles are on the facial bones of the skull.
The answer to this question varies. However, many anatomists and studies estimate that between 12 and 17 muscles are used to smile.
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