Muscles of facial expression - orbital group Flashcards
where are muscles of facial expression located?
in subcutaneous tissue
where do muscles of facial expression originate from? insert?
bone or fascia and insert onto the skin
by contracting, how do the muscles exert their effects?
by pulling on the skin
only group of muscle that inserts into the skin
what is the common embryonic origin of this group of muscles?
2nd pharyngeal arch
how do nerves innervate this group of muscles? (embryology)
as the muscles migrate from the 2nd pharyngeal arch, they take the nerve supply with them
what are all the muscles of the facial expression innervated by?
facial nerve (CN VII)
how can the facial muscles be split?
roughly into 3 groups:
orbital
nasal
oral
what does the orbital group of facial muscles contain?
2 muscles associated with the eye socket
what does the orbital group of facial muscle control?
the movements of the eyelids
important in protecting cornea from damage
innervated by facial nerve (CN VII)
what are the muscles of the orbital group?
orbicularis oculi
corrugator supercilli
where is the orbicularis oculi located?
muscle surrounds the eye socket and extends into the eyelid
what is the function of orbicularis oculi?
functionally split into 2 parts:
outer orbital part
inner palpebral part
what is the action of palpebral part of orbicularis oculi?
performs gentle closure of the eyelid
gentle palpate
what is the action of the orbital part of the orbicularis oculi?
closes eyelid fOrcefully
where is the corrugator supercilli muscle located?
much smaller muscle, located posteriorly to the orbicularis oculi muscle
where does the corrugator supercilli muscle originate and insert?
originates from superciliary arch, runs in superolateral direction
inserts into skin of eyebrown
what is the action of the corrugator supercilli muscle?
acts to draw eyebrows together, creating vertical wrinkles on the bridge of the nose
what is the innervation of corrugator supercilli?
facial nerve (CN VII)
Clinical: what happens if facial nerve becomes damaged? (in terms of orbital muscles)
orbital muscles will cease to function
Clinical: what happens if orbital muscles cease to function?
the eye cannot shut
the lower eyelid droops
clinical: what happens if the eye cannot shut?
can cause the cornea to dry out
what is it called when the cornea dries out?
exposure keratitis
result of facial nerve damage
what happens if the lower eyelid droops as a result of facial nerve damage?
lacrimal fluid pools in the lower eyelid, and cannot be spread across the surface of the eye
what can happen if the lacrimal fluid pools in the lower eyelid and cannot spread across the surface of the eye?
result in a failure to remove debris and ulceration of the corneal surface
what is it called when the lower eyelid droops?
ectropion
what is the test for facial nerve palsy?
raising the eyebrows and closing the eyelids
