Head, neck and face muscles: action, origin and insertion.

Muscles – Head, Neck, & Face

Sternocleidomastoid

Action: 

Unilateral

• laterally flex the head and neck to the same side
• rotate the head and neck to the opposite side

Bilateral

• flex the neck
• assist to elevate the rib cage during inhalation

Origin:  

• Sternal Head: top of manubrium
• Clavicular Head: medial 1/3 of the clavical

Insertion:

Mastoid process of temporal bone and the lateral portion of superior nuchal line of occiput

Scalenes

Action: Same for all the scalenes.

Unilateral

• With the rib fixed, laterally flex the head and neck to the same side.
• Rotate head and neck to the opposite side.

Bilateral

• Elevate the ribs during inhalation.
• Flex the head and neck (anterior).

Anterior Scalene

Origin: Transverse processes of third through sixth cervical vertebrae.

Insertion: First rib.

Middle Scalene

Origin: Transverse processes of second through seventh cervical vertebrae.

Insertion: First rib.

Posterior Scalene

Origin: Transverse processes of sixth and seventh cervical vertebrae.

Insertion: Second rib.

Masseter

Action: Elevate the mandible. May assist to protract the mandible.

Origin: Zygomatic arch.

Insertion: Angle and ramus of mandible.

Temporalis

Action: Elevates and retracts the mandible.

Origin: Temporal fossa and fascia.

Insertion: Coronoid process and anterior edge of ramus of the mandible.

Digastric

Action:  

• With hyoid bone fixed, depresses the mandible.
• With mandible fixed, elevates the hyoid bone.
• Retracts the mandible.

Origin: Mastoid process.

Insertion: Inferior border of the mandible.

Platysma

Action:

• Assist to depress the mandible.
• Tighten the fascia of the neck.
• Draw down the corner of the mouth.

Origin: Fascia covering superior part of pectoralis major.

Insertion: Base of mandible, skin of lower part of face.

Occipitofrontalis

Action:  

• Frontalis: Raise the eyebrows and wrinkle the forehead.
• Occipitalis: Anchor and retract the galea posteriorly.

Origin: Both: Galea apponeurotica

Insertion:  

• Frontalis: Skin superior to eyebrows.
• Occipitalis: Superior nuchal line of the occiput

Medial Pterygoid

Action:  

• Unilateral: Laterally deviates the mandible to the opposite side.
• Bilaterally: Elevates and protracts the mandible.

Origin: Medial surface of lateral pterygoid plate of sphenoid and tuberosity of maxilla.

Insertion: Medial surface of ramus of the mandible.

Lateral Pterygoid

Action:  

• Unilateral: Laterally deviates the mandible to the opposite side.
• Bilateral: Protracts the mandible.

Origin:  

• Superior head: Infratemporal surface and crest of greater wing of sphenoid bone.
• Inferior head: Lateral surface of lateral pterygoid plate of sphenoid bone.

Insertion: Articular disk and capsule of temporomandibular joint, neck of mandible.

Longus Capitis

Action:  

• Unilateral: Laterally flexes the head and neck to the same side.
• Bilaterally: Rotates the head and neck to the same side.

Origin: Transverse processes of C-3 through C-6.

Insertion: Inferior surface of occiput.

Longus Colli

Action:

• Unilateral: Laterally flexes the head and neck to the same side.
• Bilaterally: Rotates the head and neck to the same side.

Origin: Bodies of C-5 through T-3, transverse processes of C-3 through C-5.

Insertion:  

• Tubericle on anterior arch of the atlas
• Bodies of the axis, C-3 & C-4
• Transverse processes of C-5 & C-6

Rectus capitis anterior

Action: Aids in flexion of the head and the neck

Origin: Anterior surface of the lateral mass of the atlas (C1 vertebra) and the root of its transverse process[

Insertion: The inferior surface of the occipital bone anterior to the foreamen magnum

Some of these muscles are grouped into muscle groups,

below are some.

Infrahyoids (inferior to hyoid)

Action: Depress the hyoid bone and thyroid cartilage.

Origin:  

• Sternohyoid & Sternothyroid: Top of manubrium.
• Thyrohyoid: Thyroid cartilage.
• Omohyoid: Superior border of the scapula.

Insertion:  

• Sternothyroid: Thyroid cartilage.
• Sternohyoid, Thyrohyoid, & Omohyoid: Hyoid bone.

Suprahyoids (superior to hyoid)

Action: Elevate hyoid and tongue. Depresses mandible.

Origin:  

• Geniohyoid & Mylohyoid: Underside of mandible.
• Stylohyoid: Styloid process.

Insertion: Hyoid bone.

Suboccipitalis (under the occipital bone) group of 4

Rectus Capitis Posterior Major

Action: Extends and rotates atlanto-occipital joint

Origin: Spinous process of axis (C2)

Insertion: Lateral half of inferior nuchal line

        Antagonist: Extension – Longus Capitis, Rectus Capitis Anterior; Rotation – Oblique Capitis Inferior, Rectus Capitis Posterior Major; Lateral flexion – Oblique Capitis Superior, Rectus Capitis Lateralis.

Rectus Capitis Posterior Minor

Action: Extends and rotates atlanto-occipital joint

Origin: Posterior process of atlas (C1)

Insertion: Medial half of inferior nuchal line

        Antagonist: 

Oblique Capitis Superior

Action:

Origin:

Insertion:

       Antagonist:

Oblique Capitis Inferior

Action:

Origin:

Insertion:

       Antagonist:

And that is more than you will likely ever need to know about the head, neck and face.