Muscles of the eyelids and adjacent face Flashcards
What are 4 key muscles of facial expression around the eye and eyelids?
- Orbicularis oculi
- Levator palpebrae superioris
- Corrugator supercilii
- Occipitofrontalis
What is the function of orbicularis oculi in relation to the eye?
lid closure
What is the function of levator palpebrae superioris in relation to the eye?
it raises the eyelid
What is the overall shape of the orbicularis oculi muscle?
broad, flat sheet of skeletal muscle with orbital, palpebral and lacrimal portions
What are the 3 portions of the orbicularis oculi split into?
- orbital
- palpebral
- lacrimal
What is the orientation of muscle fibres in orbicularis oculi and what does this reflect?
circular orientation - sphincter-like function of muscle
From where does the orbital portion of the orbicularis oculi arise?
from the medial palpebral ligament and adjacent orbital margin
What is the orientation of fibres in the orbital portion of orbicularis oculi?
the fibres run circumferentially in an elliptical fashion around and beyond the orbital margin
most pass arounf the lateral orbital margin without interruption, but some (depressor supercilii) are inserted into the skin and connective tissue of the eyebrow
What are the depressor supercilii?
some fibres of the orbital portion of the orbicularis muscle, which are inserted into the skin and connective tissue of the eyebrow
Where is the insertion of the depressor supercilli of the orbicularis oculi (orbital portion)?
skin and connective tissue of the eyebrow
What is the palpebral portion of the orbicularis oculi muscle?
extremely thin muscle that originates from the medial palpebral ligament
Where does the palpebral portion of the orbicularis oculi muscle arise from?
medial palpebral ligament
What is the arrangement of muscle fibres in the palpebral portion of the orbicularis oculi?
fibres pass laterally within the eyelid anterior to the orbital septum and tarsal plate, and interlace to form the lateral palpebral raphe
Where is the lacrimal portion of the orbicularis oculi located?
passes deep to the medial palpebral ligament, is attached to posterior lacrimal crest (behind lacrimal sac) as two muscle slips (upper and lower)
where are the muscle fibre from the lacrimal part of orbicularis oculi inserted?
laterally into the tarsi close to the lacrimal canaliculi
What is the function of the lacrimal portion of orbicularis oculi?
help draw the eyelids and lacrimal papillae medially and in addition dilate the lacrimal sac during blinking
helps suck tears into lacrimal punctum from lacus lacrimalis
Identify the orabital and palpebral portions of orbicularis oculi on the image.
What is the nerve supply of orbicularis oculi?
temporal and zygomatic branches of facial nerve, CNVII
What is the action of the orbital portion of orbicularis oculi?
acts like purse string due to elliptical form and medial attachments: draws skin of forehead, temple, check and orbital margin towards the medial angle of the orbit, firmly closing the lids (e.g. in very bright light)
What is the action of the palpebral portion of orbicularis oculi?
can act under both voulntary and involuntary control to close the eyelids during normal blinking (and sleeping)
Why is the blink reflex important?
essential to integrity of ocular tear film and function of the cornea
What is the corrugator supercilii and where is it located?
small pyramidal muscle at medial aspect of eyebrow, beneath occipitofrontalis and orbicularis oculi
What is the action of the corrugator supercilii?
draws the eyebrow downwards and medially (frowning), producing vertical skin furrows on the forehead
What does the corrugator supercilii protect the eyes from?
assists in protecting eyes in bright light
What is the nerve supply to the corrugator supercilii?
small subdivisions of the temporal branch of the facial nerve
Which msucle acts to produce vertical skin furrows in the forehead?
corrugator supercilii
What is the structure of the occipitofrontalis?
fibromuscular layer which covers the dome of the skull from the eyebrows to the nuchal lines
consists of two occipital bellies posteriorly attached via a thick fibrous layer, the galea aponeurotica, to the two frontal bellies
What is the galea aponeurotica?
thick fibrous layer which connects the two occipital bellies of the occipitofrontalis to the two frontal bellies
How does the frontal part of the occipitofrontalis relate to the orbital region?
- fibres form a thin quadrangular sheet that is attached to the superficial fascia above the eyebrows
How are the a) medial b) intermediate c) lateral fibres of occipitofrontalis (frontal part) continuous with other facial muscles?
- a) medial = continuous with procerus
- b) intermediate = corrugator supercilii and orbicularis oculi
- c) lateral = orbicularis oculi
What is the nervous supply to the frontal belly of occipitofrontalis?
temporal branches of facial nerve
What is the action of contraction of the occipitofrontalis?
draws scalp backwards and elevates eyebrows, causing transverse wrinkles of scalp as in expressions of surprise, horror, fright, or glancing upwards
Which muscle produces horizontal forehead wrinkles?
occipitofrontalis
What is the action of levator palpebrae superioris?
opens eyelids; on relaxation, allows lid closure due to gravity
What is the location of levator palpebrae superioris?
within orbit
What is the origin of the levator palpebrae superioris?
lesser wing of sphenoid, above and in front of optic foramen, bleding with origin of superior rectus
Which muscle does the origin of levator palpebrae superioris blend with?
superior rectus
Where does the levator palpebrae superioris extend from, from its origin?
- muscle belly passes horizontally forward above the superior rectus, close to the orbital roof
- behind the orbital margin it curves downwards into the lid where it becomes aponeurotic
What is the organisation of the aponeurosis of levator palepbrae superioris?
the aponeurosis fans out on either side to form medial and lateral horns, which extend the whole width of the eyelid
What is the insertion of levator palpebrae superioris?
inserts into skin of upper lid (causing horizontal palepbral sulcus or furrow) and anterior surface of the tarsal plate
What is formed by the lateral horn of the LPS aponeurosis?
lateral palpebral ligament
What is the insertion of the lateral palpebral ligament (formed by lateral horn of LPS aponeurosis)?
inserts into the lateral orbital tubercle
What does the medial horn of the aponeurosis of LPS become?
medial palpebral ligament
What is the site of insertion of the medial palpebral ligament?
frontolacrimal suture
What is the nerve supply to the levator palpebrae superioris?
superior division of the oculomotor nerve
What is the action of the LPS on contraction?
elevates the upper lid, thereby opening the palpebral fissure
What can be found on the inferior aspect of the levator palpebrae superioris?
superior tarsal or Müller’s muscle
What is the attachment of the superior tarsal / Müller’s muscle?
attached anteriorly to the upper surface of the tarsal plate and cojunctival fornix
What is the innervation to the superior tarsal/ Muller’s muscle on the inferior aspect of LPS?
sympathetic innervation
What is the action of contraction of the superior tarsal / Muller’s muscle?
assists levator in elevating eyelid
What is the closest equivalent to the superior tarsal in the lower eyelid?
small group of smooth muscle fibres (inferior tarsal muscle) that originate from the fascial sheath of inferior rectus and insert into the lower tarsus
