There are many muscle groups in the head and neck. We will break these down into manageable chunks for learning. We will start with the muscles of facial expression.
By the end of this lesson, you should know their functions, origins, insertions and nerve supply.
Please note that the images show the main muscle anatomy, and may have other relevant anatomy missing (eg. nerves, vessels, bones etc.) in order to focus on the muscles.
The photos have been created for visual aids- these may not be entirely anatomically accurate but are there to aid your learning.
There are many muscles of facial expression, and many sources differ when discussing the key ones. This covers the main aspects of the muscles of facial expression, and will divide them into manageable groups.
All muscles of facial expression are derived from the 2nd pharyngeal arch and are supplied by motor control by the Facial Nerve (CN VII).
These muscles all insert into areas of the skin to control its movement.
Note: The modiolus is a 'knot' of several facial muscles, near the angle of the mouth.
| Muscle | Origin | Insertion | Action | Other |
| Buccinator | Buccinator ridge on Alveolar process of Mandible and Maxilla Maxilla: Pterygomandibular raphe | Angle of mouth and lateral portion of upper and lower lips | Creates sucking action and controls bolus | Controls food synergistically with tongue + provides muscular structure of cheek. |
| Muscle | Origin | Insertion | Action | Other |
| Mentalis | Incisive fossa of Mandible | Skin of chin/lower lip | Elevation and protrusion of lower lip and skin of chin | Used in 'pouting'. |
| Muscle | Origin | Insertion | Action |
| Anterior auricular | Anterior part of temporal fascia | Helix of ear | Draws ear forwards |
| Superior auricular | Epicranial aponeurosis on side of head | Upper part of auricle | Elevates ear |
| Posterior auricular | Mastoid process of temporal bone | Convexity of concha of ear | Draws ear upward and backward |
These muscles tend to be involuntary and can be very small movements.
| Muscle | Origin | Insertion | Action | Other |
| Orbicularis oculi – orbital | Medial palpebra ligament + frontal process of maxilla + nasal portion of frontal bone | Fibres form muscle around the orbit and attach to overlying skin | Forceful closure of eyelid | |
| Orbicularis oculi – palpebral | Medial palperbral ligament and lacrimal bone | Lateral palpebral raphe | Gentle closure of eyelid | |
| Orbicularis oculi - Lacrimal | Lacrimal bone | Lacrimal fascia | Aids tears | |
| Corrugator Supercilii | Superciliary arch/Supraorbital ridge of frontal bone | Skin of eyebrow | Draws eyebrows together - frowning (medially and inferiorly) | Posterior to orbicularis oculi |
| Muscle | Origin | Insertion | Action | Other |
| Procerus | Nasal bone + lateral nasal cartilage | Skin overlying bridge of the nose | Wrinkles skin over the bridge of the nose | |
| Depressor Septi | Maxilla | Nasal bone aponeurosis/Nasal septum | Brings septum forward to constrict nostril | Antagonistic to Dilator Naris |
| Nasalis – Dilator Naris | Maxilla | Nostril cartilage | Flares nostrils | |
| Nasalis - Compressor Naris | Maxilla | Its counterpart on the other side of the face | Constricts nostrils |
| Muscle | Origin | Insertion | Action | Other |
| Orbicularis oris | Anteromedial surface of maxilla and mandible + modiolus | Skin and fascia of lips | Compression and protrusion of lips | Used to purse lips shut |
| Levator Anguli oris | Canine fossa of maxilla | Angle of the mouth | Elevation of angle of the mouth | |
| Depressor anguli oris | Anterolateral part of inferior border of mandible (near external oblique line) | Angle of mouth and blends with fibers of orbicularis oris | Pulls angle of mouth laterally and downward | Antagonises elevator anguli oris |
| Zygomaticus major | Zygomatic bone (in front of zygomaticotemporal suture) | Angle of mouth | Raise upper lip, smiling | Inserts more into angle of mouth |
| Zygomaticus minor | Zygomatic bone (in front of zygomaticotemporal suture) | Upper lip | Raise upper lip, smiling | Above major, Inserts into middle part of upper lip |
| Risorius | Facsia of lateral cheek and parotid | Skin of angle of mouth | Aids in grimacing by pulling corners of mouth laterally | |
| Levator Labii Superioris | Infra-orbital margin of maxilla | Skin of upper lip | Elevation of upper lip | Important when administering infraorbital injections |
| Depressor Labii Inferioris | Anterolateral part of body of Mandible (below mental foramen) | Middle portion of lower lip; blends with fibres of other side | Pulls lip downwards and laterally | |
| Levator labii superioris alequae nasi | Upper frontal process of maxilla | Skin of lateral part of nostril and upper lip | Lifts upper lip + nose | Also dilates the nose |
| Muscle | Origin | Insertion | Action | Other |
| Occipitofrontalis | Galea aponeurotica of scalp – attached to overlying dense CT and skin | Subcutaneous tissue in region of forehead and eyebrows (galea aponeurosis) | Pulls back scalp, Wrinkles forehead, Elevates eyebrows and skin of forehead | Has no bony attachment |
This muscle can sometimes be split into the occipitalis and frontal. In this case, the origin of the occipitalis is classed as the mastoid process + superior nuchal line (1).
An easy way to remember the layers of the scalp, is that it is its own mnemonic:
See 'The Neck' lesson for more detail on the muscles involved.
In terms of innervation by the facial nerve and a muscle of facial expression, the platysma muscle is considered part of this group.
| Muscle | Origin | Insertion | Action | Other |
| Platysma | Fascia of pectorals and deltoid muscles | Inferior border of the mandible | Wrinkles skin of the neck. | External jugular vein lies beneath the platysma (1) |
We work around the head and neck muscles everyday, so it is important to know where they are and how they work.
As you can see, the muscles of facial expression are an important group, not only for patient movement, but to identify parafunction in the Facial Nerve (CN VII) or if an ID block has been administered too distally.
You should now be aware of which muscle is affected if a movement cannot be elicited.
Move onto the next lesson to cover the next group of muscles: The Muscles of Mastication.
Books:
Please note: The images in this lesson are original drawings and have been used by collating and averaging images from the sources above.
