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Muscles of the eyes

The left panel shows the lateral view of the muscles for the right eye, and the right panel shows the anterior view of the muscles for the right eye.
(a) The extrinsic eye muscles originate outside of the eye on the skull. (b) Each muscle inserts onto the eyeball.
Muscles of the Eyes
Movement Target Target motion direction Prime mover Origin Insertion
Moves eyes up and toward nose; rotates eyes from 1 o’clock to 3 o’clock Eyeballs Superior (elevates); medial (adducts) Superior rectus Common tendinous ring (ring attaches to optic foramen) Superior surface of eyeball
Moves eyes down and toward nose; rotates eyes from 6 o’clock to 3 o’clock Eyeballs Inferior (depresses); medial (adducts) Inferior rectus Common tendinous ring (ring attaches to optic foramen) Inferior surface of eyeball
Moves eyes away from nose Eyeballs Lateral (abducts) Lateral rectus Common tendinous ring (ring attaches to optic foramen) Lateral surface of eyeball
Moves eyes toward nose Eyeballs Medial (adducts) Medial rectus Common tendinous ring (ring attaches to optic foramen) Medial surface of eyeball
Moves eyes up and away from nose; rotates eyeball from 12 o’clock to 9 o’clock Eyeballs Superior (elevates); lateral (abducts) Inferior oblique Floor of orbit (maxilla) Surface of eyeball between inferior rectus and lateral rectus
Moves eyes down and away from nose; rotates eyeball from 6 o’clock to 9 o’clock Eyeballs Superior (elevates); lateral (abducts) Superior oblique Sphenoid bone Suface of eyeball between superior rectus and lateral rectus
Opens eyes Upper eyelid Superior (elevates) Levator palpabrae superioris Roof of orbit (sphenoid bone) Skin of upper eyelids
Closes eyelids Eyelid skin Compression along superior–inferior axis Orbicularis oculi Medial bones composing the orbit Circumference of orbit

Muscles that move the lower jaw

In anatomical terminology, chewing is called mastication    . Muscles involved in chewing must be able to exert enough pressure to bite through and then chew food before it is swallowed ( [link] and [link] ). The masseter    muscle is the main muscle used for chewing because it elevates the mandible (lower jaw) to close the mouth, and it is assisted by the temporalis    muscle, which retracts the mandible. You can feel the temporalis move by putting your fingers to your temple as you chew.

Muscles that move the lower jaw

The left panel of this figure shows the superficial chewing muscles in face, and the right panel shows the deep chewing muscles.
The muscles that move the lower jaw are typically located within the cheek and originate from processes in the skull. This provides the jaw muscles with the large amount of leverage needed for chewing.
Muscles of the Lower Jaw
Movement Target Target motion direction Prime mover Origin Insertion
Closes mouth; aids chewing Mandible Superior (elevates) Masseter Maxilla arch; zygomatic arch (for masseter) Mandible
Closes mouth; pulls lower jaw in under upper jaw Mandible Superior (elevates); posterior (retracts) Temporalis Temporal bone Mandible
Opens mouth; pushes lower jaw out under upper jaw; moves lower jaw side-to-side Mandible Inferior (depresses); posterior (protracts); lateral (abducts); medial (adducts) Lateral pterygoid Pterygoid process of sphenoid bone Mandible
Closes mouth; pushes lower jaw out under upper jaw; moves lower jaw side-to-side Mandible Superior (elevates); posterior (protracts); lateral (abducts); medial (adducts) Medial pterygoid Sphenoid bone; maxilla Mandible; temporo-mandibular joint

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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