The document discusses the anatomy and functions of the eyelids. It describes the structures that make up the eyelids, including the tarsal plates, lacrimal papilla, lacrimal canaliculi, and orbicularis oculi muscle. It also discusses eyelid movements such as blinking, winking, peering, and forceful closure which are mediated by muscles like the levator palpebrae superioris and orbicularis oculi muscle. Various eyelid abnormalities and neurological control of eyelid muscles are also summarized.

6. • The tarsi (tarsal plates) are two comparatively thick,
elongated plates of dense connective tissue, about 10
mm (0.39 in) in length for the upper eyelid and 5 mm for
the lower eyelid; one is found in each eyelid, and
contributes to its form and support.
• They are located directly above the lid margins.

10. • An eye is said to have a Mongoloid slant
when the outer canthus is placed higher
than the inner canthus while in the
antimongoloid slant, the outer canthus is
placed lower than the inner canthus.

12. The lacrimal papilla is the small rise in the bottom
(inferior) and top (superior) eyelid just before it
ends at the corner of the eye closest to the nose. At
the medial edge of it is the lacrimal punctum, a small
hole that lets tears drain into the inside of the nose
through the lacrimal canaliculi.

15. The lacrimal canaliculi, (sing. canaliculus), are the small
channels in each eyelid that drain lacrimal fluid, from
the lacrimal puncta to the lacrimal sac. This forms part of
the lacrimal apparatus that drains lacrimal fluid from the
surface of the eye to the nasal cavity.

18. Abnormalities in Eyelashes
1. Trichiasis
2. Pseudotrichiasis
3. Madarosis
4. Poliosis
5. Trichomegaly
6. Distichiasis is a rare condition where you
have two rows of eyelashes.

20. Trichiasis Madarosis
Poliosis
Distichiasis
Trichomegaly

31. • Adnexa: The eyebrows, eyelids, eyelashes, lacrimal gland
and drainage apparatus all play a crucial role with regards to
globe protection, lubrication and minimising the risk of ocular
infection. These adnexal structures also help create the
optimum environment for corneal transparency and therefore
clear vision.
• The epidermis, the outermost layer of skin,
provides a waterproof barrier and creates our skin
tone.
• The dermis, beneath the epidermis, contains tough
connective tissue, hair follicles, and sweat glands.

34. • The orbicularis oculi muscle is a muscle located in the
eyelids.
• It is a sphincter muscle arranged in concentric bands around
the upper and lower eyelids.
• The main function of the orbicularis oculi muscle is to close
the eyelids.
• This occurs when the muscle contracts.

40. FACIAL NERVE (CN VII)

41. BLOOD SUPPLY
• The orbicularis oculi muscle receives its blood from the
branches of the facial artery and superficial temporal artery
(which are branches of the external carotid artery), as well as
the ophthalmic artery (which is a branch of the internal carotid
artery).

44. • The arcus marginalis is a distinct white fibrous
thickening of the peripheral 1 to 3 mm of the orbital
septum.

47. • The superior tarsal muscle, known as Muller's muscle, is a
structural muscle which functions to maintain the elevation of
the upper eyelid.

49. • Aponeurosis is a type of connective tissue found throughout the
body. Aponeuroses provide an attachment point for muscles to
connect to bone, and can also envelope muscles and organs,
bind muscles together, and bind muscles to other tissues.
• They are important for muscle movement and posture.

58. • Lockwood ligament, the transverse fascial
structure that supports the eyeball, stabilizes
it, providing the framework for inferior rectus and
oblique muscles of the eye.

61. Medial Palpebral Ligament (MPL)
Lateral Palpebral Ligament (LPL)

67. • Sebaceous gland, small oil-producing gland.
• Sebaceous glands are usually attached to hair follicles and
release a fatty substance, sebum, into the follicular duct and
thence to the surface of the skin.
• The normal function of sebaceous glands is
to produce and secrete sebum.
• Sebum lubricates the skin to protect against
friction and makes it more impervious to moisture.
A specialized sebaceous gland in the eyelids is
called meibomian gland. It is found in the tarsal plate
in the eyelid and secretes an oily substance,
specifically referred to as meibum oil.

75. • The angular vein is a vein located between the top of the
nose and the eye.
• The internal jugular vein is a paired venous structure that
collects blood from the brain, superficial regions of the
face, and neck, and delivers it to the right atrium.
• The superficial temporal vein is a vein of the side of the
head.
• The external jugular vein is a superficial vein of the neck
that drains blood from the parotid gland, most of the
scalp, and side of the face, then back to the heart.

77. NERVE SUPPLY
1. Motor nerves are facial nerves ( which supplies orbicularis
muscle) and oculomotor nerve ( which supplies LPS).
2. Sensory nerves derived from branches of the first and second
divisions of trigeminal nerve.Those supplying the upper eyelid
include supraorbital,supratrochlear, infratrochlearand lacrimal
nerves.The lower eyelid is supplied by infraorbital,lacrimal and
infratrochlear nerves.
3. Sympathetic nerves: supply the non striated muscle (Muller’s
muscle), the vessels and the glands of the skin.

79. • The eyelids are highly movable covers for the exposed parts of
the eyes.
• These move more than any other part of the body.
• Basically, the eyelid movements include opening and closing;
however, depending upon the purpose, mechanics and neural
control, they have been classified into
- Blinking
- Winking
- Peering
- Forceful closure

80. OPENING MOVEMENTS
• Salient points concerned and associated with the opening movements
of the eyelids are as follows:
• Muscles concerned with opening are levator palpebrae superioris
(which is the primary elevator of upper eyelid), frontalis (acting as
accessory elevator) and the superior palpebral muscle of Muller's
(functioning for long-term adjustments in the upper eyelid position).
• In the lower eyelid, these are the elastic recoil of the lower eyelid
tissues, traction exerted by the attachment of the inferior rectus to the
inferior tarsus and inferior palpebral muscle of Muller's for relatively long
term adjustments in position.

81. • The frontalis muscle is responsible for elevating the eyebrows.
The frontalis muscles are a pair of vertically oriented
muscles in the forehead that lift the eyebrows.
• When one contracts the forehead muscle it causes elevation
of the brows with simultaneous development of horizontal
wrinkles in the forehead.
• During opening movement, the upper lid moves vertically
upwards, while the lower lid moves laterally in a horizontal
direction.

83. CLOSING MOVEMENTS
• Muscle concerned with closing movement of the eyelids is
orbicularis oculi, which is supplied by facial nerve. There are three
functional units in the orbicularis oculi:
1. Those responding in spontaneous blinking and tactile corneal
reflex are pretarsal fibres.
2. Those responding to voluntary blinking and sustained activity
include preseptal fibres in addition to the pretarsal.
3. Those responding in forceful closure of the eyelid include all the
three portions of orbicularis, viz. pretarsal, preseptal and orbital
fibres.

85. Blepharospasm is a rare condition that causes your
eyelid to blink or twitch. This is called involuntary blinking
or twitching. The twitching is caused by a muscle
spasm around your eye.

86. UPPER EYELID VERSUS LOWER EYELID DURING
CLOSING MOVEMENTS
• Direction of movement : Upper eyelid moves downwards
(vertically) while the lower lid moves medially (in horizontal
direction).
• Rate of movement : Rate of movement of the upper and lower
eyelids is similar during closing movement.
• Closing movements of both upper and lower eyelids occur in
phase, although movement of the lower eyelid begins some 10-
20 msec before the movement can be detected in the upper
eyelid.

87. PEERING
• Peering refers to the act of looking at some object with great
interest. During the process of peering, the degree of eye
movements is constant. Similar to closing movement, in the process
of peering also the movement of lower eyelid begins some 200
msec before the movement could be detected in the upper eyelid.
However, it is definite that the relaxing phase of peering is initiated
by relaxation of tone in the orbicularis muscle, and is characterised
by a slow return of the upper and lower eyelids to their normal alert
open position.

89. BLINKING
• Blinking refers to a co-ordinated opening and closing movements of the
eyelids.
• A blink may be complete or incomplete.
• A complete blink may be defined as a movement of both eyelids, which
begins in the normal alert open position, reaches a half way point when
the upper and lower eyelids' ciliary margins appose each other along at
least one half of their ciliary margins, and ends when the upper and
lower eyelids return to the starting, alert open position.
• Blinking can be divided into voluntary and involuntary types.
• The involuntary blinks are further subdivided into spontaneous and reflex
blinks.

92. SPONTANEOUS BLINKING
• Spontaneous blinking, as the name indicates, is a common form of
blinking that occurs without any obvious external stimulus or
voluntary willed efforts.
• It occurs at frequent intervals during the waking hours in all
animals with lids.

94. REFLEX
• Reflex blinking refers to the co-ordinated closing and
opening movements of the eyelids which occur reflex in a
response to some direct stimulus.
• Depending upon the type of stimulus, the reflex blinking
can be subdivided into
- Tactile
- Optic
- Auditory
- Stretch reflex blinking

95. 1. Tactile reflex blinking : It is excited by a sudden unexpected
touch to cornea, conjunctiva, eyelash, eyebrow or eyelids.
2. Optic reflex blinking: It includes the dazzle reflex produced by
shinning a bright light into the eye and the menace reflex
produced by an unexpected or threatening object coming
suddenly into the near field of vision.
3. Auditory reflex blinking: It is excited by loud noises.
4. Stretch type stimulus reflex blinking: This type of reflex blinking
occurs when the orbicularis is stimulated by a stretch type
stimulus such as a tap or blow

96. VOLUNTARY BLINKING AND WINKING
• A co-ordinated closure and opening movement of the eyelids,
when carried out as a willed act in both eyes is called voluntary
blinking; and when carried out in one eye only (the other eye
remaining open) is called winking.
• Voluntary blinking and winking are produced by simultaneous
contraction of palpebral and orbital portions of the orbicularis
muscle.
• The voluntary blinking is under the control of the individual, i.e.
the rate and degree of closure and opening can be varied as per
will.
• It has been observed that a voluntary maximum forced closure
can be maintained for less than 20 sec by most individuals.

97. BLEPHAROSPASM
• Blepharospasm refers to the involuntary sustained and forceful
closure of the eyelids. This entails contraction of all the portions of
orbicularis muscle as well as muscles of the eyebrows. The
contraction of the orbicularis may be tonic, with the lids locked shut
for a period of time.

98. BELL'S PHENOMENON
• Bell's phenomenon is a highly coordinated reflex between the
facial and oculomotor nuclei, whereby on closure of the eyelids,
the eyeball is rotated upward and outward.
• This is a protective mechanism that brings the cornea up under
the covering eyelid, and away from impending danger.
• Inverse Bell's phenomenon is present, whereby the globes
rotate downward and outward on attempted closure. When
inverse Bell's phenomenon is associated with lagophthalmos
(inability to close the lids) severe corneal drying and ulceration
(exposure keratitis) may occur.

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