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Lecture 10

BLG 700 Lecture Notes - Lecture 10: Levator Labii Superioris, Levator Palpebrae Superioris Muscle, Levator Anguli Oris

6 pages101 viewsFall 2013

Course Code
BLG 700

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Muscular System
Divisions of Skeletal Muscle System (Fig 10.1, 10.2)
Axial musculature origins on axial skeleton
o positions head and vertebral column and assists in breathing by moving rib cage
Appendicular musculature stabilizes or moves components of appendicular skeleton
Axial Muscles
4 groups based on location and/or function
o head and neck muscles, muscles of vertebral column, muscular walls of thoracic and
abdominopelvic cavities, muscles of the perineum and pelvic diaphragm
Head and Neck Muscles (Fig 10.3-10.9, Table 10.1-10.6)
originate on skull or hyoid bone and not associated with vertebral column
muscles of facial expression, extra-ocular muscles, muscles of mastication, muscles of the
tongue, muscles of the pharynx, and anterior muscles of the neck
o responsible for verbal and non-verbal communication, feeding, and movement of eyes
Facial Expression (Fig 10.3, 10.4, Table 10.1)
o cutaneous muscles origins on surface of skull and insertions via collagenous fibers of
epimysium (connective tissue wrapping skeletal muscles) woven into dermis of skin
allow skin to twitch to remove irritants (e.g. insects)
important in non-verbal communication
o largest group associated with movement of mouth
closing and puckering lips:
orbicularis oris closes lips constricts opening while other muscles move lips
or corners of mouth
o origin = nasal septum, maxilla, and mandible
buccinator flattens cheek allows suckling and puckering
o origin = mandible and maxilla
zygmaticus major and minor elevate and abduct upper lip; origin = zygomatic
levator anguli oris elevates angle of mouth; origin = maxilla
risoris abducts angle of mouth: origin = fascia of masseter
levator labii superioris elevates upper lip; origin = maxilla
pouting or frowning:
depressor anguli oris depresses angle of mouth; origin = mandible
depressor labii inferioris depresses lower lip; origin = mandible
mentalis- protrudes lower lip; origin = mandible
o smaller group controls movement of eyebrows, eyelids, scalp, nose and external ear
occipitofrontalis raises eyebrows and furrows skin of forehead; origin = occipital
bone; insertion = skin of eyebrow and nose
orbicularis oculi loses eelids ad auses o’s feet; oigi = maxilla and
frontal bones
levator palpebrae superior (Fig 10.5) raises upper lids; origin = lesser wing of
sphenoid bone
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ptosis = droopy eyelid on one side usually indicates nerve damage leading to
the muscle (levator palpebrae superioris)
corrugator supercilii draws eyebrows inferiorly and medially producing vertical
corrugations between eyes origin = nasal bridge
Extra-Ocular Muscles (Fig 10.5, Table 10.2)
o 6 extra-ocular (extrinsic eye) muscles rotate eyeball within orbit to allow vision in a
wider range of directions
o origins = surface of orbit, insertions = sclera (thick fibrous outer layer of wall of eye)
o rectus muscles = nearly straight with axis of eye and rotate eye in direction of their
superior rectus look up
inferior rectus look do
superior and inferior are slightly offset so also bring eye medially
lateral rectus aduts ee look to the side
medial rectus adduts ee look to the ose
o oblique muscles = oriented at an oblique axis of the eye inserting into posterior lateral
superior oblique oes ee do ad out
inferior oblique oes ee up ad out
o diplopia = double-vision - each eye not focused on same image and get two separate
can result from paralysis or weakness of certain extrinsic muscles or neurological
o strabismus = congenital weakness of external eye muscles in which eye rotates medially
oss-eed o lateall all-eed
to compensate eyes may alternate focusing on objects, or only the controllable eye
may be used and the brain ignores the input from the other eye making it
functionally blind (amblyopia)
Mastication (Fig 10.6, Table 10.3) = chewing
o move mandible at temporomandibular joint
o elevators of mandible brings mandibular teeth forcefully against maxillary teeth to
crush food
masseter elevates and protracts mandible; origin = zygomatic arch, insertion =
mandibular ramus
most powerful and important muscle
temporalis elevates and retracts mandible; origin = temporal fossa of parietal
bone, insertion = mandibular ramus and coronoid process of mandible
medial pterygoid elevates and protracts mandible; origin = pterygoid plate of
sphenoid bone
lateral pterygoid protracts and depresses mandible; origin = pterygoid plate of
sphenoid bone
o slight mandibular depression due to relaxation of the elevators and pull of gravity
slak ja
o grinding food between teeth = medial and lateral excursion of mandible and all
muscles of mastication
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