Muscles Flashcards
What are the 4 Muscles of Mastication:
- Masseter Muscle
- Temporalis
- Medial Pterygoid
- Lateral Pterygoid
What are the Origin, Insertion and Action of the Masseter Muscle?
ORIGIN: superficial – anterior 2/3rd of inferior border of zygomatic arch, runs down and back.
INSERTION: Lateral surface of the angle of the mandible and posterior border of the ramus.
ACTION: Elevates (closes) and clenches teeth. Slightly protrudes
What are the Origin, Insertion and Action of the Temporalis?
ORIGIN: Temporal Fossa. Fibers converge as they move vertically passing under zygomatic arch.
INSERTION: Medial and anterior surface of the coronoid process and the anterior border of the ramus
ACTION: Elevates or closes jaw, clenches teeth. Retrudes the mandible.
What are the Origin, Insertion and Action of the Medial Pterygoid (aka interal pterygoid)?
ORIGIN: Medial surface of the lateral pterygoid plate and few fibers from the maxillary tuberosity. Fibers run down and back.
INSERTION: Medial surface of the angle of the mandible.
ACTION: Elevation of the mandible.
What are the Origin, Insertion and Action of the Lateral Pterygoid (aka external pterygoid)?
ORIGIN: 2 heads – Larger inferior head: lateral surface of the lateral pterygoid plate.
Smaller superior head - infratemporal surface of the greater wing of sphenoid.
INSERTION: Inferior head – neck of condyle (also fibers into the capsule).
Superior head - articular capsule and articular disc of the TMJ.
*both heads insert into the fibers of the capsule and neck of the condyle.
ACTION: Opening movements of the jaw, protrusive, and lateral excursive.
What are the 4 muscles of the Suprahyoid Group and what is the main function?
Act to depress the mandible
- Digastric Muscle
- Mylohyoid Muscle
- Geniohyoid Muscle
- Stylohyoid Muscle
What are the Origin, Insertion and Action of the Digastric Muscle?
ORIGIN: Mastoid (or digastric) notch just medial to the mastoid process of the temporal bone. Fibers run down and forward to the intermediate tendon which attaches to the hyoid.
INSERTION: Fibers continue from the intermediate tendon forward to insert into the area of the digastric fossa.
ACTION: Retrudes the mandible. Lifts the larynx when the teeth are clenched (swallowing) and assists in depression of the mandible.
What are the Origin, Insertion and Action of the Mylohyoid muscle?
ORIGIN: Mylohyoid line.
INSERTION: Hyoid bone, posterior aspect only. Other is median raphe.
ACTION: Depression of the mandible or elevation of hyoid bone.
What are the Origin, Insertion and Action of the geniohyoid muscle?
ORIGIN: Genial tubercle.
INSERTION: Hyoid bone.
ACTION: Depressor of the mandible or elevator of hyoid bone.
What are the Origin, Insertion and Action of the stylohyoid muscle?
ORIGIN: Styloid process.
INSERTION: Hyoid bone. Muscle splits and part of digastric passes through it.
ACTION: A stabilizer. Pulls the hyoid gone backward and upward, unlike other suprahyoids this one is not a depressor
What are the 4 muscles of the Infrahyoid Group and what is their main function?
Stabilize the hyoid bone.
- Omohyoid Muscle
- Sternohyoid Muscle
- Sternothyroid Muscle
- Thyrohyoid Muscle
What are the Origin, Insertion and Action of the Omohyoid muscle?
ORIGIN: Inner surface of scapula.
INSERTION: Hyoid bone.
ACTION: Pulls hyoid downward.
What are the Origin, Insertion and Action of the sternohyoid muscle?
ORIGIN: Sternum – upper border.
INSERTION: Hyoid bone.
ACTION: Pulls hyoid downward.
What are the Origin, Insertion and Action of the sternothyroid muscle?
ORIGIN: Sternum – upper part.
INSERTION: Thyroid cartilage.
ACTION: Pulls larynx downward.
What are the Origin, Insertion and Action of the Thyrohyoid Muscle?
ORIGIN: Thyroid cartilage.
INSERTION: Hyoid bone.
ACTION: Lifts the thyroid cartilage and raises the larynx or helps to depress the hyoid bone.
What are the Origin, Insertion and Action of the Sternocleidomastoid muscle?
ORIGIN: Sternum – upper part and medial 1/3 of clavicle (collarbone).
INSERTION: Mastoid process.
ACTION: Tilt or rotate the head.
What are the Origin, Insertion and Action of the trapezius muscle?
ORIGIN: Occipital protuberance and superior nuchal lines. Also from spinous process of cervical and thoracic vertebrae.
INSERTION: Scapula and lateral 1/3 of clavicle.
ACTION: Adduct and elevate the scapula and to slightly rotate it. Motion of shrugging shoulders.
What are the Origin, Insertion and Action of the scalp (epicranius (occipitofrontalis) or epicranial?
ORIGIN: 2 bellies – front belly originates at the CT of the scalp at the epicranial aponeurosis (tendon at the area of the occipital and parietal bones). Occipital part originates from the occipital bone and mastoid process
INSERTION: Front belly inserts into the skin tissue of the eyebrow and root of the nose. Occipital belly inserts into the tendon mentioned above.
ACTION: Raises forehead, eyebrows and moves scalp. “Surprise” expression.
What are the Origin, Insertion and Action of the neck (platysma)?
ORIGIN: Inferior border of the mandible
INSERTION: CT of the chest just below the clavicle and shoulder.
ACTION: Moves skin over neck area; upwards from clavicle and downwards from corners of mouth and mandible. “Grimace” expression. “eeeeekk”
What are the Origin, Insertion and Action of the eyes (orbicularis oculii)?
** 2 parts: Palpebral part, (Levator Palpebrae Superioris) fibers in upper eyelids and Orbital part circles eyes.
ORIGIN: Palpebral – upper lid and upper edge of orbit.
Orbital – medial and lateral edges of orbit.
INSERTION: Same as above.
ACTION: Palpebral part lifts upper eye lids while the Orbital part closes eyelids and contracts tissue around the eyes. “Winking”.
What are the Origin, Insertion and Action of the eyes (corrugator)?
ORIGIN: Bridge of nose region (frontal bone) and medial supraorbital.
INSERTION: Laterally to superior region of eyebrow.
ACTION: Pulls brow downward and medially “Frown”.