Transcript a. Lacrimal nerve

DEPARTMENT OF ANATOMY
Head and Neck
Dr. SREEKANTH THOTA
Gross Anatomy
Eye
ORBIT
• The orbits are bilateral structures in the upper
half of the face below the anterior cranial fossa
and anterior to the middle cranial fossa that
contain the eyeball, the optic nerve, the
extraocular muscles, the lacrimal apparatus,
adipose tissue, fascia, and the nerves and
vessels that supply these structures.
Bony orbit
• Seven bones contribute to the framework
of each orbit
• 1. Roof
• 2. Medial wall
• 3. Floor
• 4. Lateral wall
Openings Into the Orbital Cavity
•
•
•
•
•
1. Supraorbital notch (Foramen)
2. Nasolacrimal canal
3. Superior orbital fissure
4. Optic canal
5. Infraorbital groove and canal
Eyelids
• The layers of the eyelids, from anterior to
posterior, consist of
• 1.Skin, subcutaneous tissue
• 2. Voluntary muscle
• 3.orbital septum
• 4.Tarsus
• 5. Conjunctiva
Muscles of the Eyelid
1.Orbicularis oculi:
• Closes the eyelid…. Important in blinking.
• Facial nerve palsy results in inability to close the eye
& can cause excessive dryness & irritation of the
eye. [patient may sleep with eyes partially open!]
• 2. Muscles for elevating upper eyelid
1. levator palpebrae superioris
2. Superior tarsal (Muller’s muscle)
Orbicularis oculi
Ptosis:
• Can result due to
oculomotor nerve
palsy (levator
palpebrae superioris)
OR
• Due to Damage to
sympathetic nerves
supplying Muller’s
muscle. (Horner’s
syndrome)
The eye lid
Chalazion:
A chalazion , is a cyst in
the eyelid that is caused
by inflammation of a
blocked meibomian gland or
tarsal gland usually on the upper
eyelid.
Chalazion
Stye
An external stye is an
infection of
the sebaceous glands of
Zeis at the base of
the eyelashes, or an
infection of
the apocrine sweat glands
of Moll.
Extra
occular
muscles
NERVE SUPPLY OF EXTRAOCULAR MUSCLES
(LR6SO4)3
Muscles of the orbit
Muscle
Medial rectus
Action on the
Eyeball
Adducts (pupil
moves
medially)
Lateral rectus
Abducts
(moving the
pupil laterally)
Superior rectus Elevates,
adducts
Nerve supply
CN III
CN VI
CN III
Muscles of the orbit
Inferior Rectus
Depresses,
adducts
CN III
Superior
Oblique
Depresses,
abducts
CN IV
Inferior Oblique Elevates,
abducts
CN III
Movements of the eyeball
ACTION OF INDIVIDUAL MUSCLES ON THE EYEBALL
BLOOD VESSELS OF THE ORBIT
Ophthalmic Artery
• Branch of the internal carotid artery
• Passes through the optic canal
Branches:
• 1.central artery of the retina –
• 2.ciliary arteries –
• 3.lacrimal artery – to the lacrimal gland
• 4.supratrochlear
• 5.supraorbital arteries – skin of forehead
• 6. Anterior and posterior ethmoidal artery
•
•
•
•
Ophthalmic Veins
1. Superior ophthalmic vein – communicates
anteriorly with the facial vein.
2.Inferior ophthalmic vein – communicates
through the inferior orbital fissure with the
pterygoid plexus of veins
3.both veins drain into the cavernous sinus
Ophthalmic Nerve (CN V1)
a. Lacrimal nerve
– passes to the lacrimal gland providing
secretomotor fibers
b. Frontal nerve
Divides into supratrochlear and
supraorbital nerves
C. Nasociliary nerve:
Anterior and posterior ethmoidal nerve
Oculomotor nerve
• Just before entering the orbit the
oculomotor nerve [III] divides into superior
and inferior branches.
Lacrimal apparatus
• Production, movement and drainage of
fluid from the surface of the eyeball
• Composed of
-Lacrimal glands and its ducts
-Lacrimal canaliculi
-Lacrimal sac
-Nasolacrimal duct
Tears(Lacrimation)
• Parasympathetic
innervation
• Greater petrosal
branch of facial
nerve.
Conjunctiva
• Bulbar conjunctiva
covers exposed
part of sclera
• Palpebral
conjunctiva –
covers inner
surface of eyelids.
The eyeball
• Contains the optical apparatus of the eye
• Has 3 layers
1. Outer Fibrous layer-opaque sclera and
transparent anterior cornea
2. Middle Vascular layer- Choroid (posterior), Ciliary body and Iris (uvea)(anterior),
3. Inner layer (sensory)-Retina
Ciliary body
composed of the ciliary processes and ciliary muscle
• A. Ciliary processes – folds or ridges on internal
surface ciliary body  secrete aqueous humor; posterior
surface encircles the lens and connected to it by the
suspensory ligament of the lens.
• B.Ciliary muscle – consists of smooth (intrinsic)
muscle; contraction releases tension in the suspensory
ligament of the lens making it more convex and
increasing its refractive power (for near vision); nerve
supply – parasympathetic (CN III).
Production of Aqueous Humor
and Intraocular pressure
1.
Ciliary Process:
Produces Aqueous Humor
2. Posterior Chamber:
Aqueous Humor flows from
this chamber through the
pupil in Anterior Chamber
3. Canal of Schlemm
Reabsorbs Aqueous Humor
Glaucoma:
Increase in intraocular
pressure due to build up of
Aqueous Humor
• Iris
consists of two smooth (intrinsic)
muscles that control the size of
the pupil
• Sphincter pupillae – circular
arranged fibers; constricts
(closes) pupil in presence of bright
light; nerve supply parasympapathetic (CN III)
• Dilator pupillae – radially
arranged fibers; dilates (opens)
pupil in presence of low intensity
light or in presence of excessive
sympathetic activity as occurs in
fright; nerve supply – sympathetic
Lens
• It is an encapsulated,
elastic, biconvex
transparent structure.
• Suspensory ligament
connects it to the ciliary
body.
Cataracts
 Cataracts - clouding or opacification of
the natural lens of the eye
 Cataract Vision
Cataract
• A cataract is any opacity within a lens. The
opacity can be very small (incipient cataract)
and not interfere with vision.
• It can involve more of the lens (immature
cataract) and cause blurred vision.
• Eventually, the entire lens can become cloudy,
and all functional vision lost. This is called a
mature cataract.
How can cataracts be treated?
• The only treatment for cataracts
is surgical removal.
• Cataract surgery is the removal
of the eye lens and replacing it
with an artificial one.