Download Gross Anatomy SESSION 13 Dr. Firas M. Ghazi Orbital region

Gross Anatomy
SESSION 13
Dr. Firas M. Ghazi
Orbital region
Curricular Objectives
By the end of this session students are expected to:
Theory
1. Define the orbital region and review the location of its main content
2. Recall the location, boundaries and landmarks of orbit and the spaces related
3. Outline the layered structure of the eyelids and the muscles acting on it
4. Describe the conjunctival sac and its functional importance
5. List the structures of the lacrimal apparatus and acknowledge their function
6. Summarize the nervous control of lacrimation
7. List the main content of the orbital cavity
8. Underline the names, attachment, action and nerve supply of extra ocular muscles
9. Paraphrase the process of eye blinking, its anatomical control & functional importance
10. Outline the three coats of the eye ball and their subdivisions
11. Discuss the structure & nutrition of the cornea & its importance in the process of vision
12. Summarize the parts and functions of the ciliary body
13. Review the two muscles of the iris, their actions and nerve supply
14. Describe the different parts of the retina and its role in the process of vision
15. Outline the cavities and other content within the eye ball
16. Review the structure, attachment and function of the lens
17. Discuss the applied anatomy of corneal, accommodation and light reflexes
Practical
1. Label the major content of the orbital region
2. Identify major landmarks and foramina within the orbital cavity
3. State the main structures passing through major foramina of the orbit
4. List and locate the main spaces adjacent to the orbital cavity
5. Mark the parts of the eyelids & name the space with which upper eyelid communicates
6. Label the muscles contributing to eye blinking and state their nerve supply
7. Recognize the conjunctival sac and its parts
8. Locate the different parts of lacrimal apparatus & name the nerve supplying the gland
9. Distinguish the extra ocular muscles and state the nerve supply of each
10. Trace the optic nerve and state its function
11. Identify the three coats of the eye ball and their different parts
12. Locate the eye structures involved in corneal, light and accommodation reflexes
13. State the nerves involved in corneal reflex
14. Label the structures of living human eye visible by direct inspection
Selected references and suggested resources
 Clinical Anatomy by Regions, Richard S. Snell, 9th edition
 Grant's Atlas of Anatomy, 13th Edition
 McMinn's Clinical Atlas of Human Anatomy, 7th Edition
 Anatomy for Babylon medical students (facebook page)
 Anatomy for Babylon medical students (youtube channel)
 Human Anatomy Education (facebook page)
 Human anatomy education (youtube channel)
Feedback and suggestions
 http://goo.gl/forms/SjyjGeUpvH
Further assistance on:
University website: http://staff.uobabylon.edu.iq/site.aspx?id=93
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Gross Anatomy
SESSION 13
Dr. Firas M. Ghazi
Session check list
 Clinical highlights
 Clinical problems include refractive errors, red eye, foreign body, Cataract, & Glaucoma
 Many eye problems like exophthalmus, and retinopathy are caused by systemic diseases
 Suggested links and videos
1. http://www.healthline.com/human-body-maps/eye (3D interactive eye anatomy )
2. https://youtu.be/TXFt1Ikl__I (Eye ball and extrinsic muscles)
3. https://youtu.be/RE1MvRmWg7I (function of the eye)
4. https://youtu.be/p_xLO7yxgOk (accommodation reflex)
5. https://youtu.be/cldYYtejPwo (corneal reflex)
 Orbital Cavity
 It contains the eyeball, the extraocular muscles, the optic nerve and three more cranial nerves
 Eye lids
 They consist of five layers (From superficial to deep):
 Skin, Superficial fascia, Orbicularis oculi (palpebral fibers), Orbital septum, & Conjunctiva
 The Orbital septum is the framework of eyelids it is made of palpebral fascia which extends
from the orbit margins and the tarsal plate
 The sub-aponeurotic space (scalp) is continuous with upper eyelid deep to orbicularis oculi
 The conjunctival sac is a potential space between the palpebral and bulbar conjunctiva
 The superior & inferior fornices are made by reflection of conjunctiva from lids to eye ball
 Lacrimal apparatus (the pathway of the tears)
 The lacrimal apparatus consists of all the structures concerned with secretion and drainage of
lacrimal (tear) fluid
 Lacrimal gland & Ducts >> Conjunctival sac >> Lacrimal puncta >> Lacrimal canaliculi >>
Lacrimal sac >> Nasolacrimal duct
 Ducts of the lacrimal gland pierce the lateral part of the superior fornix
 Lacrimation is under parasympathetic control
 Extra-ocular muscles and the eye movement
 Are muscles within the orbital cavity but outside the eyeball
 There are six muscles moving the eyeball and one muscle elevate the upper eyelid
 They move the eye outward (abduct) inward (adduct) upward (elevate) downward (depress)
 Conjugate movements is said to occur when both eyes move in the same direction
 Nerve supply of the extra-ocular muscles: L6(SO4)3
 Levator palpebrae superioris is composed of two parts. One with skeletal muscle fibers and
other with smooth muscle fibers. Each part is innervated differently
 Memorizing the muscles and the nerves responsible for individual eye movement is of great
clinical importance to help diagnose many ophthalmological and neurological illnesses
 Three coats of the eye ball
 They eye ball is made of three layers forming its internal structure
1. Fibrous coat (external layer): Sclera/ Cornea/ Corneoscleral junction (limbus)
2. Vascular (uveal) coat (middle layer): Choroid/ Ciliary body/ Iris
3. Nervous coat (internal layer): Retina/ Macula lutea/ Fovea centralis/ Optic disc
Further assistance on:
University website: http://staff.uobabylon.edu.iq/site.aspx?id=93
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Gross Anatomy
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SESSION 13
Dr. Firas M. Ghazi
The cornea is avascular and nourished by permeation from capillaries at the limbus, aqueous
humour, and lacrimal fluid
The corneal reflex is the closure of the eyelids on touching the cornea
The ciliary body is a complex of three structures. Its main functions are:
a) Secrete aqueous humour
b) Suspend the lens via suspensory ligaments
c) Focus the lens to adapt for near vision
The iris has two muscles
a) Constrictor pupillae (parasympathetic supply)
b) Dilator pupillae (sympathetic supply)
The retina is multilayered structure contain photoreceptor cells called rods and cones
The optic disc is where all nerve fibers from retinal ganglion cells collect to exit as optic nerve
 Circulation of aqueous humor
 The aqueous humor flow in this direction:
Posterior chamber >> pupil >> anterior chamber >> Iridocorneal angle >> canal of Schlemm
 Obstruction of aqueous humor flow will increase intraocular pressure (glaucoma).
 Lens
 It tend to assume spherical shape but the contraction of ciliary body make it less convex
 Its main function is the accommodation for near vision
 Nice to know:
 When the eye is open and looking straight ahead, the upper lid just covers the upper margin
of the cornea. Knowing this fact help diagnose exophthalmos
 Ptosis is the drooping of upper eyelid as a result of paralysis of Levator palpebrea superioris
 The red eye effect seen in flash photography is due to light being reflected from the highly
vascular choroid layer.
Lab activity list
For each task below, identify the listed structures then answer the related questions
 Task 1 (Orbit and orbital content):
 Orbital opening/ orbital margin/ Supraorbital notch (Foramen)
 Roof/ floor/ medial wall/ lateral wall/ apex
 Inferior orbital fissure/ Superior orbital fissure/Optic canal/ Nasolacrimal canal
 Extra ocular muscles/ eyeball/ optic nerve
 What are the structures passing through the superior orbital fissure?
 What are the structures passing through the optic canal?
 Task 2 (Spaces related to different walls of the orbit):
 Anterior cranial fossa/ middle cranial fossa/ Pterygopalatine fossa
 Maxillary sinus/ ethmoid sinuses
 The inferior orbital fissure connects the orbit with two spaces. Name them
 The superior orbital fissure connects the orbit with _____________________
Further assistance on:
University website: http://staff.uobabylon.edu.iq/site.aspx?id=93
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Gross Anatomy
SESSION 13
Dr. Firas M. Ghazi
 Task 3 (Eye lids/ palpebrae):
 Upper and lower eye lids/ lashes/ palpebral fissure
 Skin and conjunctival surfaces of the eyelids/ mucocutaneous junction
 Superior and inferior tarsal plates/ Medial and Lateral palpebral ligaments
 Levator palpebrae superioris/ orbicularis oculi (palpebral & orbital parts)
 Superior and inferior fornices
 Levator palpebrae superioris muscle insert into ______________________
 Which muscle control forceful closure of the eyelids?
 Which muscle opens the eye?
 Task 4 (The lacrimal apparatus):
 Lacrimal gland/ conjunctival sac/ Lacus lacrimalis
 Lacrimal punctum/ Lacrimal canaliculus and Lacrimal sac/ Nasolacrimal duct
 What is the function of the lacrimal fluid?
 Which nerve supply the lacrimal gland?
 Closure of the nasolacrimal duct will cause ____________________
 Task 5 (The extraocular muscles):
 Superior rectus/ Inferior rectus/ Medial rectus/ Lateral rectus
 Superior oblique/ Inferior oblique
 Superior and inferior recti rotate the eye ball medially why?
 To which part of the orbit the four recti attach?
 How to identify the recti from the oblique muscles?
 The Levator palpebrae superioris muscle lies __________________ to recti (superficial/deep)
 Task 6 (Coats of the eye ball):
 Sclera/ Cornea/ Corneoscleral junction (limbus)
 Choroid/ Ciliary body/ Iris
 Retina/ Macula lutea/ Fovea centralis/ Optic disc >>> Optic nerve
 Which of the structures above provide attachment to the extraocular muscles?
 Which cranial nerve supplies the cornea?
 Which of these structures is called the blind spot and why?
 The structure that has cones only is ___________________
 Task 7 (Content and spaces of the eye ball):
 Anterior compartment: Anterior chamber/ Pupil/ Posterior chamber
 Lens
 Posterior compartment: Vitreous body
 Draw a diagram showing the refractive apparatus of the eye
 Lens can become more spherical by _________________
Further assistance on:
University website: http://staff.uobabylon.edu.iq/site.aspx?id=93
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Gross Anatomy
SESSION 13
Dr. Firas M. Ghazi
Review questions:
1. Name the muscles that can elevate the eye
2. Which nerve is injured if the eye cannot be abducted?
3. What are the afferent and efferent limbs of corneal reflex?
4. Draw a simple diagram labeling the eye structures and nerves involved in accommodation reflex?
5. Regarding the picture on the right
A. Structure (1) meets the cornea at……..
B. Colored structure (2) is called………
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C. The space behind structure (3) is called…….
D. Which muscle opposes the action of structure (4)?
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E. Parasympathetic ganglion supplying (5) is……..
F. Which one of these structures is involved in
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corneal reflex?
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Homework
1- There is a difference in the pattern of blood supply of the sclera and cornea.
A. Explain
B. How does that affect the healing process of these two structures?
C. Soft plastic contact lenses worn for long periods must be permeable to the air. Why?
2- A 40-year-old male presented with headache and impaired vision of his left eye. Examination
revealed that his left eye was displaced downward and laterally, with ptosis, and dilated pupil.
A. Which nerve is most likely affected?
B. List the extra ocular muscles that are NOT likely affected.
C. Explain the ptosis in this case.
D. What muscle causes pupil to dilate? What nerve supply it?
3- At one station of clinical OSCE examination, a 6th year medical student was prompted to examine
the light reflex of a patient`s eye. Later on he had to interpret his findings by recalling his
anatomical knowledge regarding this reflex.
A. What is the afferent limb of this reflex?
B. What is the efferent limb of this reflex?
C. Name the muscle constricting the pupil
4- What is Horner’s syndrome and what features of this syndrome are seen in the picture below?
Horner’s syndrome:
Image source: http://dxline.info/diseases/horner-syndrome
Further assistance on:
University website: http://staff.uobabylon.edu.iq/site.aspx?id=93
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