Eyebrow and eyelid Flashcards
What is the function of the eyebrow
Eyebrow diverst sweat/ Prevent perspiration from driping into the eyes from the forehead
Forms part of the facial expression
Name the four muscles that controls facial expression
Orbital portion of orbicularis oculi
Occipito-frontalis muscle
Corrugator supercilii
Procerus
Where is the orbicularis oculi located
Directly underneath the skin, surrounding the orbital margin
What is the action of the orbicularis oculi muslce
Closes the eyelid by voluntary control (orbital portion)
Where is the occipito-frontalis muscle located
Covers the skull, extending from the eyebrow to the back of the head
What is the action of the frontalis muscle
Draws back the scalp to raise the eyebrows, and wrinkles the forehead
What is the location of the corrugator supercilii
Beneath occipito frontalis, just above orbicularis oculi
What is the action of the corrugator supercilii
Draws the eyebrows downward and medially, producing vertical wrinkles in the forehead
What is location of the procerus
Pyramid shaped muscle at the nasl bones between the eyebrows
What is the action of the procerus
Pulls the eyebrows downward that assists in flaring the nostrils, producing horizontal frown in the forehead
What are the three synergistic actions of extreme upward gaze
Upward rotation of globe
Elevation of the upper eylids
Elevation of the eyebrows
Can the eyebrow be elevated voluntarily alone?
Yees
What is the nerve supply of the eyebrow
Motor innervator from facial nerve (CN VII)
Temporal branch
- Orbicularis oculi
- occipto-frontalis muscle
- corrugator supercilii
Upper bucal branch
- procerus
What is the blood supply to the eyebrow
Arteriral supply:
- supraorbital and supratrochlear branch of ophtlamic artery
Drainage:
- angular vein, enters the facial vein
Are eyebrows moved during the ordinary act of blinking
No
Where does the upper and lower eyelids meet
Inner canthus (medial) and outer canthus (lateral)
What are the structures located in the inner canthi
Lacus lacrimalis, where the eyelids are separeted by a small triangular space
In the center of lacus lacrimalis is th caruncle (a elevation, also known as caruncular lacrimalis)
Lateral to caruncle is the plica semilunaris (the fold of the conjuncitva)
Papilla, a small elevation 5mm from inner canthus
Punctum, located on the summit of the papilla (carries tears down the nose)
How long does it take for eyelashes to get replaced
100-150 days
What are the functions of the eyelashes
Protect the cornea
Screen and sense action
Reflex blinking
- each follicle is surrounded by a erve plexus with a very low threshold of excitation. Touching a cilium excites the nerve plexus of the folicle and produce a reflex blinking protecting the eye from the entrance of foreign particles anda against trauma
What are the six layers of the eyelid
- Skin
- Subcutaneous tissue
- Striated and non striated muscle fibres
- Orbital septum and tarsal plates
- Submuscular areolar tissue
- Conjunctiva
What is located in the skin layer of the eyelid
Epidermis has numerous melanocytes
Behind and between lash follicles are
- sweat glands
- Glands of Moll and Zeis (precent drying of lashes by producing lipids)
What is the skin continous with
Continous with the palpebral conjunctiva just in front of the poserior edge at the orifices of the tarsal glands
What is the subcutaneous tissue / areolar connective tissue layer made of and what happens if damaged
Loose and rich in elastic fibres
A potential cavity that allows haemorrhage (black eyes) and lymph fluids (puffy eye) to accumulate
What are the muscles present in the striated muscles layer of the eyelid
Orbicularis oculi (flat and elliptical muscle, consists of thin bundles of fibres and forms the bulk of the lids)
Ciliary portion of orbicularis oculi (muscle of Riolan)
Leveator palpebral superioris (LPS)
What are the two portions of orbicularis oculi and what are the actions it carries out respectively
Orbital portion: voluntary closing of eyelids
Palpebral portion: voluntary and involunatry closing of eyelids
Which nerve innervartes the orbicularis oculi muscle
Temprla and zygomatic barnches of facial nerve (CN VII)
What is the action of the muscle of Riolan
Ensure good closure of the lids and keeps lid margins close to the eyeball
What tissue is fused with the LPS and SR’s muscle sheath and why
The connective tissue of the conjunctival stroma
Ensures that the conjunctiva is moved as the globe or upper lid moves
How does the LPS attach to the medial and lateral orbital walls
Tendon of the levator expands into wide flat sheet (aponeurosis) and attach its extremitites to the medial and lateral orbital wals via expansions to the palpebral ligments
Aponeurosis passes between the two parts of the lacrimal gland
Which nerve innervates leveator palpebrae superioris
Superior division of oculomotor nerve (CN III)
What is the action of the LPS
Voluntary elevation of the upper eyelid
What is the muscle located in the non straited muscle layer of the eyelid
Superior muller’s muscles
- LPS inferior lamellae contains smooth muscle whihc forms the superior tarsal of Muller
What is the action of the Superior Muller’s muscle
Involuntary control, helps to sustain the action of LPS, keeping the lids open when awake
Give a breif description of the Meibomian glands
A gland that runs vertically in the tarsal plate from lid margin, orfices just in front of the posterior edge of the lid margin, marks the junction betweenm the skin and the conjunctiva
Where does the submuscular areolar tissue
A thin layer that lies between the orbicularis and the tarsal plate
What are the primary and secondary muscles in charge of eyelid opening
Primary muscle:
Leveator plapebrae superioris, superior and inferior Muller muscles
Secondary muscle:
Occipito- frontalis muscle
What are the primary and secondary muscles in charge of eyelid closing
Primary muscle:
Orbicularis Oculi
Secondary muscle:
Corrugator supercilii, procerus
What are the two types of blinking
Involuntary
- Spontanous blinking
- Reflex
- Blepharospasm
- Myokima
Voluntary blinking
- Monocular blinking
- Binocular blinking
What is the definition of blinking
rapid closure of the eyelid
What is the function of blinking
Assist in the distribution of tears over the anterior surface of the eye
- corneal wettability
- removal of particles and fumes from sensitive cornea
Helps with tear drainage at inner canthus
When does spontaneous blinking take place
Occus at regular periodic intervales of unknown origin during the waking hours
Describe in detial the process of spontaneous blinking
Lower lid remains stationary while the majority of the motion is being accomplished by the upper lid.
- Completed by a narrowing of the palpebral fissures in a zipper like action from the lateral canthus toward the medial canthus
State the functions of spontaneous blinking
Distribute uniform layer of precorneal tear film
- due to evaporation and external contaminatnts, the tear film will be disrupted in 15-20 seconds on the eye. Therefore, a periodic system of renewal is necessary to insure continous stability of the tear film
Assisits in tear drainage
What are the different types of reflex blinking
- dazzle reflex: intiate by shining a bright light into the eye
- menance reflex: intiated by the perception of sudden motion toward the eye
- auditory: intiated by loud noises
- tactile: intiated by touching of the cornea, conjunctiva or lashes
What is blepharospasm
Protective rapid lid closure
Lid closure by aqueezing of the eyelids
What causes belpharospasm
Generally caused by ocular pain
Stimulation of sensory nerve via reflex pathways connections ot the facial nerve results in contraction of orbicularis oculi
What is myokimia and what is it related to
Fibrillary twitching of the eyelid muscles
May be related to refractive errors, fatigue, alchol, caffeine, thyrotoxicosis or mental tension
What is binocular blinking
both the upper and lower lids move together to close the palpebral fissure
Upper lid movement is predominantly downward and somewhat nasal
Lower lid movement has a primary nasal direction due to strong attachment of he muscle at the medial palpebral ligament
What is the function of binocular blinking
Blocks the light during sleep
Protects eye from injuries
Preventing precorneal tear film from evaporation
What is monocular blinking
A voluntary wink is a forced closure of one eye
Which muscles cause monocular blinking
Produced by simultaneous contraction of the palpebral and orbital protions of the orbicularis muscle
What is the sensory innervation of the eyelid
Upper lid: Infratrochelar, supratrochlear, supraorbital and larimal nerves
Lower lid:
Infratrochlear, infraorbital nerve, terminal portion fo the maxiallry division of the trigeminal nerve
What is the blood supply to the eyelid
Aterial supply from lateral and medial palpebral arteries, which arise from ophthalmic artery
What nerve is innervates eyelid opening
Oculomotor (CN III)
What nerve innervates eyelid closing
Facial nerve (CN VII)
