Identify the elements of the bony orbit on a skull or x-ray.

1
Identify the elements of the bony orbit on a
skull or x-ray.

2
Indicate the structures lying superior, inferior,
medial and lateral to the eyeball and the
position of the eyeball relative to the bony
orbit.
Eyeball is oriented anteroposteriorly but orbits
are angled outward
3
Trace the flow of blood into and out of the orbit
and orbital structures.
4
Identify the extra-ocular muscles.
Side view
Levator palpebrae
Superior oblique
Optic nerve
Superior rectus
Lateral rectus (cut)
Inferior oblique
Inferior rectus
Medial rectus
Frontal views
5
Indicate the nerve supply to each.
Supratrochlear n.
Supra-orbital n.
Lacrimal n.
Frontal n.
V1
V2
II
V3
V
III
IV
VI
Sensory nerves are branches of the ophthalmic
division of the trigeminal- V1
Motor nerves are branches of cranial nerves III,
IV, and VI
6
Contrast the common clinical test for
extra-ocular muscle function with the action of
the individual muscles.

• Actions of individual extraocular muscles
• Lateral medial rectus pull eyeball medial
  laterally, respectively
• Because of different axis of orbit eyeball,
  superior inferior rectus muscles pull the
  eyeball medially as well as elevate and depress
  it
• Because of their oblique course, the superior
  inferior oblique pull the eyeball laterally as
  well as down and up
• Pure elevation is produced by the superior rectus
  inferior oblique acting together
• Pure depression is produced by IR SO

7
Contrast the common clinical test for
extra-ocular muscle function with the action of
the individual muscles.

• Clinical tests
• The best method to test eye motion is ask the
  patient to follow your finger drawing a large H
  pattern in the air a few feet from their face.
  The two legs of the H will isolate and test the
  motion of the superior/inferior rectus pair and
  inferior/superior oblique pair. The center part
  of the H will test the medial and lateral
  muscles.
• Obliques are unique and involve adduction of
  globe prior to elevation and depression

8
Predict the functional deficit resulting from
damage to each nerve.
This patient has a damaged right trochlear nerve
(IV). The right superior oblique muscle is
paralyzed. Note that movements to the right are
not affected, but movements down and, especially,
down and to the left result in asymmetrical eye
movements. The right eye is not able to move
down and in.
There is a very cool web site that allows you to
simulate the eye motions expected from lesions to
different cranial nerves and different eye
muscles. Check it out at http//cim.ucdavis.edu/Ey
es/Version1/eyesim.htm
9
Follow the course of autonomic nervous supply to
the orbital structures, indicating the pre- and
post-ganglionic sources of innervation.

• To Eyeball
• Preganglionic parasympathetic axons from
  Edinger-Westphal nucleus travel in CN III to
  ciliary ganglion
• After synapsing in ciliary ganglion,
  postganglionic axons travel to constrictor of the
  pupil and ciliary body via short ciliary nerves

• Preganglionic sympathetic axons from T1-T2 enter
  sympathetic chain and ascend to the superior
  cervical ganglion (SCG)
• After synapsing in the SCG, postganglionic axons
  join the plexus on the internal carotid artery
  and enter the orbit via its ophthalmic branch
• In the orbit, these axons travel with the
  nasociliary nerve. Some pass through the ciliary
  ganglion and enter the eyeball via short ciliary
  nerves. Others enter via long ciliary nerves.
  These innervate the dilator of the pupil.
• Other sympathetic postganglionic axons contribute
  to the innervation of the levator palpebrae muscle

10
Follow the course of autonomic nervous supply to
the orbital structures, indicating the pre- and
post-ganglionic sources of innervation.

• Innervation of the lacrimal gland
• Arises from facial nerve
• Takes pathway involving several nerves

• N. of pterygoid canal formed from
• parasympathetic preganglionic axons in greater
  petrosal n. that will synapse in pterygopalatine
  ganglion
• Sympathetic postganglionic axons from SCG cells
  that will pass through ganglion