Session 6 : Head And Neck Flashcards
What are the borders of the orbit?
Superior wall - frontal bone and the lesser wing of sphenoid
Inferior wall - maxilla, (separates it from the maxillary sinus) , palatine and zygomatic
Lateral wall - greater wing of sphenoid and zygomatic
Medial wall -ethmoid, maxilla, sphenoid and lacrimal
Which nerve will pass through the superior orbital fissure ?
C/N : Trochlear , Occulomotor and Abducens
Branches of the trigeminal nerve : Lacrimal, Nasocilliary and Frontal
Superior opthalmic vein
What runs in the inferior orbital fissure ?
Note : this inferior orbital fissure will then run into the inferior orbital Foramen in the maxillary bone
Maxillary nerve
Inferior opthalmic vein
What runs in the optic canal?
Optic nerve
Opthalmic artery
Which region of the boney orbit is most at risk to injury ?
The inferior part of the orbit is most at risk on injury: where maxillary, frontal, lacrimal and ethmoid bone run
Which kind of fractures can commonly effect the region of the eye?
Orbital rim fracture : fracture of the bones forming the iris of the orbit , zygomatic , frontal and maxilla
Blow out fracture : this can occur on the medial and inferior wall of the orbit.
In both cases the eye can fall through into the maxillary sinus.
What are the common clinical features of the an orbital fracture?
Periorbital echymosis - haemorrhage around the eye
The inferior rectus muscle becomes entrapped in this region and this results in the patient having an eye that looks down and out.
Exophthalmos -> due to raised ICP
Enophthalmos -> the sinking of the eye into the maxillary sinus.
What is the main blood vessels which supply the eye?
The branch of the internal carotid artery which is called the ophthalmic artery
The veins draining are the : superior and inferior ophthalmic vein which drain into the cavernous sinus.
What is the accomodation reflex of the eye?
When something comes toward the eye the eyes will :
Converge (come together)
Lens becomes thicker to then enable the vision to become more focused
The pupils will constrict to control the amount of light entering the eye.
What is the corneal reflex ?
The nasocilliary nerve (branch of tigeminal -> opthalmic branch) which can then detect the foreign object etc.
This then goes back to the brainstem
The motor branch is via the facial nerve will then effect the muscle orbicularis occuli to close the eye.
How do you clinically test the muscles of the eye?
Inferior oblique -> Up and in Inferior rectus -> Down and out Superior oblique -> Down and in Superior rectus -> Up and out Lateral rectus -> lateral Medial rectus -> middle
Which muscles are innervated by the occulomotor nerve ?
Medial rectus Superior rectus Inferior rectus Inferior oblique Levator superior palpebrae -> to retract the eyelid
Which muscle is innervated by the trochlear nerve?
Superior oblique
Which muscle is innervated by the abducens nerve ?
Lateral rectus
