This document discusses the anatomy and function of the human eye and its associated structures. It describes the eyes as the sensory organs of vision and their role in sight. It then outlines the seven cranial nerves involved in eye movement and function. The document proceeds to discuss the extraocular and intraocular muscles, focusing on the ciliary muscles responsible for accommodation and their role in vision at different distances. It also details the layers of the ciliary epithelium and eye lids, as well as their functions and blood supply.

1. SENSE ORGANS
Shri Vishnu College of Pharmacy (Autonomous)
Affiliated to Andhra Univ., Visakhapatnam; Approved by AICTE and PCI, New Delhi, and recognised by APSCHE
Prepared by
Grandhi Sandeep Ganesh
Dept. of Pharmacology

2. EYE
 The sensory organs of vision are the eyes
 The human eye is the organ which gives us the sense
of sight, allowing us to observe and learn more
about the surrounding world than we do with any of
the other four senses
 We use our eyes in almost every activity we
perform, whether reading, working, watching
television, writing a letter, driving a car, and in
countless other ways
 Each eye is situated in the orbit- a bony cage. It
consists of upper & lower eyelids, the upper eye lid
covers a upper portion of the cornea but does not
overlap the pupil. The space between the two eyelids
is called aperture

3. CRANIAL NERVES OF EYE
The seven cranial nerves of the eye are
 CN II – For vision
 CN III & IV – Eye movement
 CN III – Papillary reaction
 CN III – Eyelid elevation
 CN VII – Eyelid closure

4. ORBITAL MUSCLES
Orbital Muscles
Intra Ocular Extra Ocular
Ciliary Muscles Involuntary Voluntary
• Superior
Tarsal muscle
• Inferior tarsal
muscle
• Levator Palpebrae
superioris
• Superior rectus
• Inferior rectus
• Medial rectus
• Lateral rectus
• Superior oblique
• Inferior oblique

5. CILIARY MUSCLES
 The ciliary muscle changes the shape of the lens – (this is called
accommodation)
 It relaxes to flatten the lens for distance vision; for close work it contracts
rounding out the lens. Everyone will develop an eye condition called
presbyopia
 As we age, the ciliary muscle and crystalline lens lose their elasticity.
This is why most people need reading glasses by their 40’s
 The ciliary muscle consists of three separate muscle fibers: longitudinal,
circular and oblique

6. CILIARY MUSCLES
 The longitudinal fibers (meridional), which are the most external, attach
the ciliary body anteriorly to the scleral spur and trabecular meshwork at
the limbus, and posteriorly to the supracoroidal lamina (fibers connecting
choroid and sclera) as far back as the equator of the eye
 The contraction of the longitudinal muscle, opens the trabecular
meshwork and Schlemm`s canal
 The circular fibers (sphincteric) make up the more anterior and inner
portion, and run parallel to the limbus. This insertion is in the posterior
iris. When these fibers contract, the zonules relax, increasing the lens
axial diameter and its convexity
 The oblique fibers (radial or intermediate) connect the longitudinal and
circular fibers. The contraction of these fibers may widen the uveal
trabecular spaces

7. CILIARY EPITHELIA
 The inner surfaces of the ciliary processes and
the pars plana are lined by two layers of
epithelium
 The outer layer is the pigmented epithelium,
which is composed of low cuboidal cells and is
adjacent to the stroma and continuous with the
retinal pigmented epithelium.
 The inner layer is formed by the nonpigmented
epithelium, a columnar epithelium, adjacent to
the aqueous humor in the posterior chamber
and continuous with the retina.
 These two layers of the epithelium are
appositioned in their apical surfaces.

8. EYE LIDS
 It is skin without subcutaneous fat
 It has 4 basic layers
 From anterior to posterior the layers are
 Skin and subcutaneous connective tissue
 Muscle
 Tarsus
 Conjunctiva
Functions of eye lids
 Protect eye ball
 Lubricate anterior surface of globe (by
blinking the tear film spread over anterior
surface)
Blood supply to the lid
 Lacrimal artery and vein