Extraocular Muscles & Extrinsic Tongue Muscles

Front 1

Extraocular Muscles

Back 1

- muscles found within orbit, but outside of eyeball
- total of 7 muscles - one for the upper eyelid, 6 that move teh eyeball

Front 2

Muscles of teh upper eyelid

Back 2

1) Levator Palpebrae Superioris - raises upper eyelid (palpabrae = "eyelid")
a) innervated by oculomotor nerve (CN III)

Front 3

Muscles of eyeball
x 6

1 - 4

Back 3

1) Superior Rectus - passes in straight line to upper side of eyeball (rectus = "straight")
a) innervated by oculomotor nerve
2) Inferior Rectus - to inferior side of eyeball
a) innervated by oculomotor nerve (CN III)
3) Medial Rectus - to medial side of eyeball; adducts eye (moves eye towards mid-line)
a) Innervated by oculomotor nerve (CN III)
4) Lateral Rectus - to lateral side of eyeball; abducts eye (moves eye away from mid-line)
innervated by abducent nerve (CN VI)
- all rectus muscles arise from common origin at posterior aspect of orbit
- only medial and lateral rectus move eye around single axis of rotation (produce pure motion); other muscles move eye around 2 axis of rotation (produce mixed motions)

Front 4

Muscles of eyeball
x 6

5 - 6

Back 4

5) Superior Oblique
a) arises from common origin with rectus muscles at posterior orbit
b) runs down superior-medial wall of orbit
c) passes through trochlea located at superior-medial corner of anterior orbit
1) muscle makes a 135 degree bend, then passes diagonally, posteriorly, and laterally across superior eyeball before attaching
2) trochlea = L "pulley
d) innervated by the trochlear nerve (CN IV)
6) Inferior Oblique
a) arises from medial floor of anterior orbit (behind lower eyelid)
b) passes diagonally, postriorly, and laterally running diagonally across to attach to inferior side of eyeball
c) innervated by oculomotor nerve
- both oblique muscles produce mixed motions

Front 5

Innervation of Extraocular Muscles

Back 5

1) Oculomotor Nerve CN III - enters orbit through superior orbital fissure
a) supplies levator palpabrae superioris muscle and 4 muscles of eyeball: superior rectus, medial rectus, inferior rectus, and inferior oblique muscle
b) also carries preganglionic parasympathetic fibers
1) preganglionic fibers synapse in Ciliary Ganglion (located within orbit, behind eye)
2) Postganglionic parasympathetic fibers innervate iris (for constriction of pupil) and ciliary muscle (increases focusing strength of lens for near viewing)
2) Trochlear N. CN IV - enters orbit via superior orbital fissure
a) motor to superior oblique muscle (muscle that passes through trochlea)
3) Abducent Nerve CN VI - enters orbit via superior orbital fissure
a) motor to lateral rectus muscle (muscle that abducts eye)

Front 6

Lacrimal Gland

Back 6

1) Located in superior, lateral region of anterior orbit (behind upper eyelid)
2) gland that produces tears of eye
a) tears provide moisture and nutrients to cornea of eyeball
b) tears drain at medial corner of eye - pass down nasolacrimal canal into nasal cavity

Front 7

Extrinsic Muscles of the Tongue
x 3

#1 Genioglossus M.

Back 7

major extrinsic muscle of the tongue
a) Origin - mental spine of mandible
b) Insert - fibers fan out superiorly & posteriorly near mid-line, along entire length of tongue
1) anterior fibers go to tip of tongue
2) middle fibers go to body of tongue
3) posterior fibers curve back, downward and attach to Hyoid bone
c) Action - protrudes tongue from mouth

Front 8

Extrinsic Muscles of the Tongue
x 3

#2 Hyoglossus M.

Back 8

a) Origin - Hyoid bone
b) Insert - fibers pass upward and forward into lateral sides of tongue
c) Action - retracts and flattens tongue

Front 9

Extrinsic Muscles of the Tongue
x 3

#3 Styloglossus M.

Back 9

a) Origin - styloid process of skull
b) Insert - runs forward into tongue
c) Action - retracts tongue

Front 10

Innervation of tongue

Back 10

1) Motor - from hypoglossal nerve CN XII
2) Sensory - anterior 2/3 of togue
a) general sensory - mandibular division of trigeminal nerve V 3 (activated by hot peppers, pain)
b) taste - facial nerve CN VII
3) Sensory - posterior 1/3 of tongue
a) general sensory & Taste glossopharyngeal nerve CN IX