anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

, the orbital septum (palpebral fascia) is a

membranous A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. ...

sheet that acts as the anterior (frontal) boundary of the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

. It extends from the orbital rims to the

eyelid An eyelid is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. The human eyel ...

s. It forms the fibrous portion of the eyelids.

Structure

In the upper eyelid, the orbital septum blends with the tendon of the

levator palpebrae superioris The levator palpebrae superioris ( la, elevating muscle of upper eyelid) is the muscle in the orbit that elevates the upper eyelid. Structure The levator palpebrae superioris originates from inferior surface of the lesser wing of the sphenoid bo ...

, and in the lower eyelid with the

tarsal plate The tarsi (tarsal plates) are two comparatively thick, elongated plates of dense connective tissue, about in length for the upper eyelid and 5 mm for the lower eyelid; one is found in each eyelid, and contributes to its form and support. They ...

. When the eyes are closed, the whole orbital opening is covered by the septum and tarsi. Medially it is thin, and, becoming separated from the

medial palpebral ligament The medial palpebral ligament (medial canthal tendon) is a ligament of the face. It attaches to the frontal process of the maxilla, the lacrimal groove, and the tarsus of each eyelid. It has a superficial (anterior) and a deep (posterior) layer ...

, attaches to the lacrimal bone at its posterior crest. The medial ligament and its much weaker lateral counterpart, attached to the septum and orbit, keep the lids stable as the eye moves. The septum is perforated by the vessels and nerves which pass from the orbital cavity to the

face The face is the front of an animal's head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may aff ...

and

scalp The scalp is the anatomical area bordered by the human face at the front, and by the neck at the sides and back. Structure The scalp is usually described as having five layers, which can conveniently be remembered as a mnemonic: * S: The ski ...

Clinical significance

Orbital septum supports the orbital contents located posterior to it, especially orbital fat. The septum can be weakened by trauma or due to hereditary diseases. Anatomical structures important in the

blepharoplasty Blepharoplasty (Greek: ''blepharon'', "eyelid" + ''plassein'' "to form") is the plastic surgery operation for correcting defects, deformities, and disfigurations of the eyelids; and for aesthetically modifying the eye region of the face. With t ...

operation (operation to strengthen the orbital septum) are located posterior to the orbital septum. The orbital septum is an important structure that separates anterior and posterior extent of the orbit. Orbital septum acts as a physical barrier that prevents the infection of the anterior part of the eye spreading posteriorly. For example,

preseptal cellulitis Periorbital cellulitis, or preseptal cellulitis (not to be confused with orbital cellulitis, which is posterior to the orbital septum), is an inflammation and infection of the eyelid and portions of skin around the eye anterior to the orbital sept ...

mainly infects the eyelids, anterior to the orbital septum. Meanwhile,

orbital cellulitis Orbital cellulitis is inflammation of eye tissues behind the orbital septum. It is most commonly caused by an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood. It may also occur after trauma. W ...

is located posterior the orbital septum, due to infections spreading from the

ethmoidal sinus The ethmoid sinuses or ethmoid air cells of the ethmoid bone are one of the four paired paranasal sinuses. The cells are variable in both size and number in the lateral mass of each of the ethmoid bones and cannot be palpated during an extraoral ...

es. The porous

lamina papyracea The orbital lamina of ethmoid bone, (or lamina papyracea or orbital lamina) is a smooth, oblong bone plate which forms the lateral surface of the labyrinth of the ethmoid bone in the skull. The plate covers in the middle and posterior ethmoidal ...

separating the orbit from the ethmoidal sinus causes infection to spread between the orbit and ethmoidal sinuses. Infection of the ethmoidal sinuses can spread to the brain, causing

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...

and

cerebral abscess Brain abscess (or cerebral abscess) is an abscess caused by inflammation and collection of infected material, coming from local (ear infection, dental abscess, infection of paranasal sinuses, infection of the mastoid air cells of the temporal bone ...

. Orbital cellulitis can also spread to the anterior orbit, by lifting the loosely attached

periosteum The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones. Structure ...

, causing subperiosteal abscess.

Imaging

Orbital septum appears as hypointense on both MRI T1 and T2 weighted images, in contrast with surrounding hyperintense fat.

References

External links

* {{Use dmy dates, date=July 2019 Human eye anatomy Fascia

Structure

Clinical significance

Imaging

References

Further reading

External links