Muscles are either axial muscles or appendicular. The axial muscles are grouped based on location, function, or both. Some axial muscles cross over to the appendicular skeleton. The muscles of the head and neck are all axial. The muscles in the face create facial expression by inserting into the skin rather than onto bone. Muscles that move the eyeballs are extrinsic, meaning they originate outside of the eye and insert onto it. Tongue muscles are both extrinsic and intrinsic. The genioglossus depresses the tongue and moves it anteriorly; the styloglossus lifts the tongue and retracts it; the palatoglossus elevates the back of the tongue; and the hyoglossus depresses and flattens it. The muscles of the anterior neck facilitate swallowing and speech, stabilize the hyoid bone and position the larynx. The muscles of the neck stabilize and move the head. The sternocleidomastoid divides the neck into anterior and posterior triangles.
The muscles of the back and neck that move the vertebral column are complex, overlapping, and can be divided into five groups. The splenius group includes the splenius capitis and the splenius cervicis. The erector spinae has three subgroups. The iliocostalis group includes the iliocostalis cervicis, the iliocostalis thoracis, and the iliocostalis lumborum. The longissimus group includes the longissimus capitis, the longissimus cervicis, and the longissimus thoracis. The spinalis group includes the spinalis capitis, the spinalis cervicis, and the spinalis thoracis. The transversospinales include the semispinalis capitis, semispinalis cervicis, semispinalis thoracis, multifidus, and rotatores. The segmental muscles include the interspinales and intertransversarii. Finally, the scalenes include the anterior scalene, middle scalene, and posterior scalene.
anterior scalene
a muscle anterior to the middle scalene
appendicular
of the arms and legs
axial
of the trunk and head
buccinator
muscle that compresses the cheek
corrugator supercilii
prime mover of the eyebrows
deglutition
swallowing
digastric
muscle that has anterior and posterior bellies and elevates the hyoid bone and larynx when one swallows; it also depresses the mandible
epicranial aponeurosis
(also, galea aponeurosis) flat broad tendon that connects the frontalis and occipitalis
erector spinae group
large muscle mass of the back; primary extensor of the vertebral column
extrinsic eye muscles
originate outside the eye and insert onto the outer surface of the white of the eye, and create eyeball movement
frontalis
front part of the occipitofrontalis muscle
genioglossus
muscle that originates on the mandible and allows the tongue to move downward and forward
geniohyoid
muscle that depresses the mandible, and raises and pulls the hyoid bone anteriorly
hyoglossus
muscle that originates on the hyoid bone to move the tongue downward and flatten it
iliocostalis cervicis
muscle of the iliocostalis group associated with the cervical region
iliocostalis group
laterally placed muscles of the erector spinae
iliocostalis lumborum
muscle of the iliocostalis group associated with the lumbar region
iliocostalis thoracis
muscle of the iliocostalis group associated with the thoracic region
infrahyoid muscles
anterior neck muscles that are attached to, and inferior to the hyoid bone
lateral pterygoid
muscle that moves the mandible from side to side
longissimus capitis
muscle of the longissimus group associated with the head region
longissimus cervicis
muscle of the longissimus group associated with the cervical region
longissimus group
intermediately placed muscles of the erector spinae
longissimus thoracis
muscle of the longissimus group associated with the thoracic region
masseter
main muscle for chewing that elevates the mandible to close the mouth
mastication
chewing
medial pterygoid
muscle that moves the mandible from side to side
middle scalene
longest scalene muscle, located between the anterior and posterior scalenes
multifidus
muscle of the lumbar region that helps extend and laterally flex the vertebral column
mylohyoid
muscle that lifts the hyoid bone and helps press the tongue to the top of the mouth
occipitalis
posterior part of the occipitofrontalis muscle
occipitofrontalis
muscle that makes up the scalp with a frontal belly and an occipital belly
omohyoid
muscle that has superior and inferior bellies and depresses the hyoid bone
orbicularis oculi
circular muscle that closes the eye
orbicularis oris
circular muscle that moves the lips
palatoglossus
muscle that originates on the soft palate to elevate the back of the tongue
posterior scalene
smallest scalene muscle, located posterior to the middle scalene
scalene muscles
flex, laterally flex, and rotate the head; contribute to deep inhalation
segmental muscle group
interspinales and intertransversarii muscles that bring together the spinous and transverse processes of each consecutive vertebra
semispinalis capitis
transversospinales muscle associated with the head region
semispinalis cervicis
transversospinales muscle associated with the cervical region
semispinalis thoracis
transversospinales muscle associated with the thoracic region
spinalis capitis
muscle of the spinalis group associated with the head region
spinalis cervicis
muscle of the spinalis group associated with the cervical region
spinalis group
medially placed muscles of the erector spinae
spinalis thoracis
muscle of the spinalis group associated with the thoracic region
splenius
posterior neck muscles; includes the splenius capitis and splenius cervicis
splenius capitis
neck muscle that inserts into the head region
splenius cervicis
neck muscle that inserts into the cervical region
sternocleidomastoid
major muscle that laterally flexes and rotates the head
sternohyoid
muscle that depresses the hyoid bone
sternothyroid
muscle that depresses the larynx’s thyroid cartilage
styloglossus
muscle that originates on the styloid bone, and allows upward and backward motion of the tongue
stylohyoid
muscle that elevates the hyoid bone posteriorly
suprahyoid muscles
neck muscles that are superior to the hyoid bone
temporalis
muscle that retracts the mandible
thyrohyoid
muscle that depresses the hyoid bone and elevates the larynx’s thyroid cartilage
transversospinales
muscles that originate at the transverse processes and insert at the spinous processes of the vertebrae
1. Which of the following is a prime mover in head flexion?
A) occipitofrontalis
B) corrugator supercilii
C) sternocleidomastoid
D) masseter
C
2. Where is the inferior oblique muscle located?
A) in the abdomen
B) in the eye socket
C) in the anterior neck
D) in the face
B
3. What is the action of the masseter?
A) swallowing
B) chewing
C) moving the lips
D) closing the eye
B
4. The names of the extrinsic tongue muscles commonly end in ________.
A) -glottis
B) -glossus
C) -gluteus
D) -hyoid
B
5. What is the function of the erector spinae?
A) movement of the arms
B) stabilization of the pelvic girdle
C) postural support
D) rotating of the vertebral column
C
1. Explain the difference between axial and appendicular muscles.
Axial muscles originate on the axial skeleton (the bones in the head, neck, and core of the body), whereas appendicular muscles originate on the bones that make up the body’s limbs.
2. Describe the muscles of the anterior neck.
The muscles of the anterior neck are arranged to facilitate swallowing and speech. They work on the hyoid bone, with the suprahyoid muscles pulling up and the infrahyoid muscles pulling down.
3. Why are the muscles of the face different from typical skeletal muscle?
Most skeletal muscles create movement by actions on the skeleton. Facial muscles are different in that they create facial movements and expressions by pulling on the skin—no bone movements are involved.