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Questions and Answers
Which facial expression is characterized by a smile, raised cheeks, and crow's feet around the eyes?
What action is primarily performed by the frontal belly of the occipitofrontalis muscle?
Which muscle assists in closing the eye and is innervated by the facial nerve?
Which muscle is responsible for elevating the upper eyelid?
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What is the primary function of the nasalis muscle?
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The zygomaticus major is primarily responsible for which action?
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Which of the following muscle actions is associated with frowning?
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What is the innervation for the depressor anguli oris muscle?
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What feature characterizes the expression of anger?
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Which muscle can result in the flaring of the nostrils when contracted?
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What is the primary function of the buccinator muscle?
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Which muscle is responsible for elevating the angle of the mouth?
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What is the primary innervation for the facial muscles mentioned in this content?
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What is the action of the mentalis muscle?
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Which muscle assists in chewing by elevating the jaw?
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Where does the risorius muscle originate?
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What distinguishes the lateral pterygoid from the medial pterygoid muscle?
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The platysma muscle is primarily located in which region of the body?
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What is the role of the medial pterygoid muscle in mastication?
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Which structure does the masseter muscle insert into?
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Study Notes
Facial Expressions
- Happiness features a smile, raised cheeks, and crow's feet around the eyes.
- Sadness is characterized by a frown, downturned lips, and drooping eyelids.
- Anger involves furrowed brows, tightly pressed lips, and flared nostrils.
- Surprise is indicated by raised eyebrows, wide-open eyes, and a dropped jaw.
- Fear resembles surprise but is more pronounced, with wide eyes and a tense, often raised forehead.
- Disgust is characterized by a wrinkled nose, raised upper lip, and squinted eyes.
- Arrogance or superiority is shown with one side of the mouth raised (half-smile or smirk), often combined with other expressions.
Scalp Muscle: Occipitofrontalis
- Long and wide muscle of the scalp spanning from the eyebrows to the superior nuchal lines of the occipital bone.
- Comprises the epicranial group of the muscle of expression, along with the temporoparietalis.
- Consists of occipital bellies and frontal bellies, each with a pair of quadrangular muscle heads, connected by the epicranial aponeurosis (galea aponeurotica).
- The epicranial aponeurosis is a connective tissue layer that forms the third and middle layers of the scalp, connecting the frontal and occipital parts of the occipitofrontalis muscle.
- Elevates the eyebrows and wrinkles the forehead skin with its frontal part, and retracts the scalp with its occipital part.
- Origin:
- Frontal belly: skin of eyebrow, muscles of forehead.
- Occipital belly: lateral ⅔ rd of superior nuchal line.
- Insertion: Epicranial aponeurosis.
- Action:
- Frontal belly: elevates eyebrows, wrinkles skin of forehead.
- Occipital belly: retracts scalp.
- Innervation:
- Frontal belly: temporal branches of facial nerve (CN VII).
- Occipital belly: posterior auricular nerve (branch of facial nerve CN VII).
- Blood supply: superficial temporal, ophthalmic, posterior auricular, and occipital arteries.
Orbit and Eyebrow Muscles
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Orbicularis oculi
- Orbital: circular muscle around the orbit.
- Palpebral: controls spontaneous and reflex blinking.
- Origin: medial wall of the orbit.
- Insertion: circular path around orbit.
- Action:
- Closes the eye.
- Assists in tear transport and drainage.
- Forced closure: orbital and palpebral portion.
- Innervation: CN VII (facial nerve).
-
Corrugator supercilia
- Origin: medial end of superciliary arch of the frontal bone.
- Insertion: skin deep to medial eyebrow.
- Action:
- Draws eyebrow inferiorly and wrinkles skin of forehead vertically as in frowning.
- Innervation: CN VII (facial nerve).
- Droops eyelid if Botox is injected too far in this area.
- Brings brow area in and down when contracted.
- Can cause glabellar lines.
-
Levator palpebrae superioris
- Origin: roof of orbit at the lesser wing of sphenoid bone.
- Insertion: skin of upper eyelid.
- Action: elevates upper eyelid.
- Innervation: CN III (oculomotor nerve).
Nose Muscles
-
Nasalis
-
Transverse nasalis muscle:
- Located on the bridge of the nose.
- Connected from one side of the nasal cartilage to the other, blends with the procerus superiorly.
- Origin: maxilla, near the nasal bone and cartilage.
- Inserts into the skin over the bridge of the nose, particularly at the midline.
- Innervated by cranial nerve VII.
- Function: Compress the nostrils.
-
Alar nasalis muscle:
- Arises from the maxilla and extends up to the wing of the nostril (the alar cartilage), allowing it to draw the nostrils outward.
- Originates from the maxilla, just above the canine fossa.
- Inserts into the alar cartilage of the nostril and the skin of the nostril.
- Innervated by cranial nerve VII.
- Function: flaring the nostrils .
-
Transverse nasalis muscle:
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Procerus
- Origin: Fascia over nasal bone.
- Insertion: Skin between eyebrows.
- Action:
- Draws down medial eyebrows.
- Wrinkles the skin of the nose.
- Frowning and shielding eyes from bright light.
- Innervation: CN VII (Facial nerve).
-
Depressor septi nasi
- Originates from the maxilla, above the incisor teeth.
- Inserts into the nasal septum and the lower part of the cartilage of the nose.
- Function: pull the nasal septum downward to widen the nostrils.
- Aids in respiratory functions by allowing for increased airflow.
- Innervated by cranial nerve VII.
Mouth Muscles
-
Orbicularis oris
- Origin: Surrounds the mouth.
- Insertion: Skin at corner of mouth.
- Action:
- Closes the mouth.
- Protrudes the lips (like kissing).
- Compresses lips against teeth.
- Shapes lips during speech.
- Innervation: CN VII (Facial nerve).
-
Zygomaticus major
- Origin: Zygomatic bone.
- Insertion: Skin at angle of mouth and orbicularis oris (snarling).
- Action: Draws angle of mouth superiorly and laterally (smiling).
- Innervation: CN VII (Facial nerve).
-
Zygomaticus minor
- Origin: Zygomatic bone.
- Insertion: Upper Lip.
- Action: Elevates the upper lip.
- Innervation: CN VII (Facial nerve).
-
Levator labii superioris
- Origin: Superior to Infraorbital foramen of the maxilla.
- Insertion: Orbicularis oris (upper lip).
- Action:
- Elevates the upper lip.
- Main elevators of upper lip alongside the zygomaticus minor.
- Innervation: CN VII (Facial nerve).
-
Depressor labii inferioris
- Origin: Mandible.
- Insertion: Skin of lower Lip.
- Action:
- Depression of Lower Lip.
- Drawing the lower lip laterally and everting it.
- Facial expressions of sorrow, doubt, and irony.
- Innervation: CN VII (Facial nerve).
-
Depressor anguli oris
- Origin: Mandible.
- Insertion: Angle of the mouth.
- Function: Pull the corners of the mouth downward (frowning or sadness).
- Innervated by the facial nerve (cranial nerve VII).
-
Levator anguli oris
- Origin: Maxilla, just inferior to the infraorbital foramen.
- Insertion: skin of upper lip and orbicularis oris (angle of mouth).
- Action:
- Elevation of Angle of Mouth.
- Can contribute to making teeth (especially canine tooth) visible.
- Innervation: CN VII (Facial nerve).
-
Buccinator
- Located in the fleshy part of the cheek.
- Forms a significant part of the lateral wall of the oral cavity.
- Originates from the outer surfaces of the maxilla and mandible near the molars
- Originates from the pterygomandibular raphe (fibrous band that connects the maxilla to the mandible).
- Inserts into the orbicularis oris, the circular muscle surrounding the mouth, and helps to form the cheek structure.
- Function:
- Pressing the cheeks against the teeth during chewing.
- Aiding in the control of airflow during speech.
- Smiling and blowing.
- Innervated by the facial nerve (cranial nerve VII).
-
Risorius
- Situated in the lateral part of the face.
- Extends from the side of the mouth toward the masseter muscle.
- Originates from the fascia covering the masseter muscle and the superficial structures of the face.
- Inserts into the skin at the corner of the mouth, blending with the fibers of other facial muscles.
- Function: draw the corners of the mouth laterally (smiling or grinning).
- Innervation: facial nerve (cranial nerve VII).
-
Mentalis
- Origin: Mandible.
- Insertion: Skin of the Chin.
- Action:
- Elevation and protrudes lower Lip.
- Pulls skin of chin up (pouting).
- Wrinkles the skin of the chin.
- Facial expressions of doubt, pouting, or dislike.
- Innervation: CN VII (Facial nerve).
Platysma - Neck Muscle
- Found in the anterior and lateral parts of the neck.
- Extends from the upper chest and shoulder area up to the lower jaw.
- Originates from the fascia over the pectoralis major and deltoid muscles in the upper chest and shoulder region.
- Inserts into the lower mandible and the skin of the lower face, as well as the muscles around the mouth.
- Function:
- Tensing the skin of the neck.
- Depressing the mandible.
- Movements of the skin over the neck during expressions.
- Innervated by the cervical branch of cranial nerve VII.
Muscles of Mastication
- 4 pairs assist in speech:
-
Masseter
- Located at the side of the jaw.
- Origin: zygomatic arch.
- Inserts: ramus of mandible.
- Action: Elevates and closes the jaw, playing a significant role in biting and chewing.
- Innervation: mandibular division of trigeminal nerve (CN V).
-
Temporalis
- Situated on the side of the head.
- Originates at the temporal fossa of the skull.
- Insertion: coronoid process of the mandible.
- Action: Elevates and retracts the jaw.
- Helps close the jaw with vertical and horizontal forces.
- Innervation: mandibular division of trigeminal nerve (CN V).
-
Medial pterygoid
- Located on the internal (medial) side of the mandible.
- Originates at the medial surface of the lateral pterygoid plate of the sphenoid bone and the maxilla.
- Inserts at the medial surface of the angle of the mandible.
- Action: Elevates the jaw and assists in grinding movements side to side.
- Innervation: Mandibular division of trigeminal nerve (CN V).
-
Lateral pterygoid
- Located at lateral to the medial pterygoid.
- Originates at the greater wing and lateral surface of the lateral portion of the pterygoid process of sphenoid bone.
- Insertion: Condyle of mandible and articular disc of the temporomandibular joint (TMJ).
- Action: Helps to protrude the jaw and assists in moving the jaw side to side.
-
Masseter
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Description
Explore the fascinating world of facial expressions and their underlying scalp muscles in this quiz. Learn about the key characteristics of emotions such as happiness, sadness, and anger, as well as the anatomical details of the occipitofrontalis muscle. Test your knowledge on how emotions are expressed physically and the muscles that contribute to them.
