Interesting Facts About Contents of the Orbit
- Weakness or paralysis of a muscle causes squint or strabismus, which may be concomitant or paralytic. Concomitant squint is congenital; there is no limitation of movement and no diplopia.
- In paralytic squint, movements are limited, diplopia and vertigo are present, head is turned in the direction of the function of paralyzed muscle, and there is a false orientation of the field of vision.
- Nystagmus is characterized by involuntary, rhythmical oscillatory movements of the eyes. This is due to incoordination of the ocular muscles. It may be either vestibular or cerebellar, or even congenital.
- The anterior ciliary arteries arise from the muscular branches of the ophthalmic artery. The muscular arteries are important in this respect.
- The central artery of the retina is the only arterial supply to most of the nervous layer, the retina of the eye. If this artery is blocked , there is sudden blindness.
- The anastomoses between tributaries of the facial vein and ophthalmic veins may result in a spread of infection from the orbital and nasal regions to the cavernous sinus leading to its thrombosis.
- Optic neuritis is characterized by pain in and behind the eye on ocular movements and on pressure. The papilledema is less but a loss of vision the same condition is called retrobulbar neuritis.
- The common cause is demyelinating diseases of the central nervous system, any septic focus in the teeth or paranasal sinuses, meningitis, encephalitis, syphilis, and even vitamin B deficiency.
- Optic nerve has no neurilemma sheath and has no power of regeneration. It is a tract and not a nerve.
- Optic atrophy may be caused by a variety of diseases. It may be primary or sencondary.
- Surgical spaces in the orbit: These are of importance as most orbital pathologies tend to remain in the space in which ther are formed .
- Therefore, their knowledge helps the surgein in choosing the most direct surgical approach. Each orbit is divisible into four surgical spaces.
The subperiosteal space. This is a potential space between the bone and the periosteum.
The peripheral space. It is bounded peripherally by the periorbita and internally by the four recit with thin intermuscular sepat. For peribulbar ansaesthesia, injection is made in this space.
The central space.It is also called retrobulbar space. It is bounded anteriorly by the Tenon capsule lining back of the eyeball and peripherally by the four recti muscles and their intermuscular septa in the anterior part. In the posterior part, it becomes continuous with the peripheral space. Retrobulbar injections are made in this spac.
Tenon space. It is a potential space around the eyeball between the sclera and Tenon capsule.