12. Periorbital Sinuses
The eyes lie within two bony
orbits, located on either side of
the root of the nose.
They border the nasal cavity
anteriorly and the ethmoidal air
cells and the sphenoid sinus
posteriorly.
The lateral walls border the
middle cranial, temporal, and
pterygopalatine fossae.
Superior to the orbit are the
anterior cranial fossa and the
frontal and supraorbital sinus.
The maxillary sinus and the
palatine air cells are located
inferiorly.
13. Orbital Foramina
The optic foramen
The supraorbital foramen, or
notch
The anterior ethmoidal foramen
The posterior ethmoidal foramen
The zygomatic foramen
Nasolacrimal duct
Infraorbital canal
Superior orbital fissure
Inferior orbital fissure
14. Extraocular Muscles
The four recti and
two oblique muscles
All are supplied by
CN III except
superior oblique (CN
IV ) and lateral
rectus (CN VI)
15. Optic nerve
The optic nerve
consists of more
than 1 million axons
that originate in the
ganglion cell layer of
the retina and
extend toward the
occipital cortex
16. Optic Nerve
The optic nerve may be divided
into the following topographic
areas:
Intraocular portion of the optic
nerve: optic disc, or nerve head;
prelaminar; and laminar
portions
Intraorbital portion (located
within the muscle cone)
Intracanalicular portion (located
within the optic canal)
Intracranial portion (ending in
the optic chiasm)
17. Optic Chiasm
The chiasm measures
approximately 12 mm wide, 8
mm long in the
anteroposterior direction,
and 4 mm thick. The exact
location of the chiasm with
respect to the sella is
variable. Most of the time it
is directly superior
Within the chiasm, the fibers
coming from the nasal retina
(approximately 53% of total
fibers) cross to the opposite
side to join the
corresponding contralateral
fibers
18. Optic Tract
Each optic tract contains
ipsilateral temporal and
contralateral nasal
fibers from the optic
nerves . Fibers (both
crossed and uncrossed)
from the upper retinal
projections travel
medially in the optic
tract; lower projections
move laterally.
19. Lateral geniculate body
The lateral geniculate body,
or nucleus, is the synaptic
zone for the higher visual
projections
It has six alternating layers of
gray and white matter.
Layers 1, 4, and 6 of the
lateral geniculate body
contain axons from the
contralateral optic nerve.
Layers 2, 3, and 5 arise from
the ipsilateral optic nerve
20. Optic radiations
The optic radiations connect
the lateral geniculate body
with the cortex of the
occipital lobe
The fibers of the optic
radiations leave the lateral
geniculate body and run
around the temporal horn of
the lateral ventricle,
approaching the anterior tip
of the temporal lobe (the so-
called loop of Meyer)
21. Visual cortex
The visual cortex, the thinnest
area of the human cerebral
cortex
Macular function is extremely
well represented in the visual
cortex and occupies the most
posterior position at the tip of
the occipital lobe
The posterior cerebral artery, a
branch of the basilar artery,
supplies the visual cortex almost
exclusively. The blood supply to
the occipital lobe does show
anatomical variation, however,
with the middle cerebral artery
making a contribution in some
persons.
Editor's Notes
Lacrimal fossa for lacrimal gland
Fovea trochlearis at medial form a pulley of superior oblique ms where trochlea, a curved plate hyaline cartilage attached
4 bones
Maxilla (frontal process
Lacrimal
Ethmoid (orbital plate)
Lesser wing of sphenoid
Lamina papyracea – paper thin structure
Lacrimal fossa ->nasolacrimal canal -> inf meatus of nose
Roof of maxillary antrum
Made of 3 bones
- maxilla
Palatine
Zygomatic (orbital plate)
Infraorbital groove descend into a canat exit as infraorbital foramen
Inf oblique muscle, arising form floor of orbit
Blunt trauma can cause dehiscence of fragile bony floor
- diplopia, enophtalmos, hypothesia in distribution of infraorbital nerve, entrapment of orbital tissue, positive fluid level in xray of maxillarlly sinus
Thickest and strongest
Made up of zygomatic and greater wing of sphenoid
Whitnall’s tubercle -
