Levator palpebrae superioris muscle
Encyclopedia
The levator palpebrae superioris (latin for: elevating muscle of upper eyelid) is the muscle
in the orbit
that elevates the superior (upper) eyelid
.
, just above the optic foramen
. It broadens and becomes the levator aponeurosis. This portion inserts on the skin of the upper eyelid, as well as the superior tarsal plate. It is a skeletal muscle
. The superior tarsal muscle
, a smooth muscle, is attached to the levator palpebrae superioris, and inserts on the superior tarsal plate as well.
(Cranial Nerve III). This is why when one looks upward, the eyelid tends to move up with it. An adjoining smooth muscle, the superior tarsal muscle
, is sympathetically innervated and is occasionally considered to be part of the levator palpebrae superioris.
, the drooping of the eyelid. Ptosis can also be caused by damage to the adjoining superior tarsal muscle
, or its sympathetic innervation. Such damage to the sympathetic supply occurs in Horner's syndrome
, and presents as a partial ptosis.
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
in the orbit
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
that elevates the superior (upper) eyelid
Eyelid
An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...
.
Structure
The levator palpebrae superioris originates on the lesser wing of the sphenoid boneSphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...
, just above the optic foramen
Optic foramen
The optic foramen is the opening to the optic canal.The superior surface of the sphenoid bone is bounded behind by a ridge, which forms the anterior border of a narrow, transverse groove, the chiasmatic groove , above and behind which lies the optic chiasma; the groove ends on either side in the...
. It broadens and becomes the levator aponeurosis. This portion inserts on the skin of the upper eyelid, as well as the superior tarsal plate. It is a skeletal muscle
Skeletal muscle
Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...
. The superior tarsal muscle
Superior tarsal muscle
The superior tarsal muscle is a smooth muscle adjoining the levator palpebrae superioris muscle that helps to raise the upper eyelid.-Structure:...
, a smooth muscle, is attached to the levator palpebrae superioris, and inserts on the superior tarsal plate as well.
Innervation
As with most of the muscles of the orbit, it is innervated by the superior division of the oculomotor nerveOculomotor nerve
The oculomotor nerve is the 3rd of 12 paired cranial nerves. It enters the orbit via the superior orbital fissure and controls most of the eye's movements, including constriction of the pupil and maintaining an open eyelid by innervating the Levator palpebrae superiors muscle. The optic nerve is...
(Cranial Nerve III). This is why when one looks upward, the eyelid tends to move up with it. An adjoining smooth muscle, the superior tarsal muscle
Superior tarsal muscle
The superior tarsal muscle is a smooth muscle adjoining the levator palpebrae superioris muscle that helps to raise the upper eyelid.-Structure:...
, is sympathetically innervated and is occasionally considered to be part of the levator palpebrae superioris.
Pathology
Damage to this muscle, or its innervation, can cause ptosisPtosis (eyelid)
Ptosis is a drooping of the upper or lower eyelid. The drooping may be worse after being awake longer, when the individual's muscles are tired. This condition is sometimes called "lazy eye", but that term normally refers to amblyopia...
, the drooping of the eyelid. Ptosis can also be caused by damage to the adjoining superior tarsal muscle
Superior tarsal muscle
The superior tarsal muscle is a smooth muscle adjoining the levator palpebrae superioris muscle that helps to raise the upper eyelid.-Structure:...
, or its sympathetic innervation. Such damage to the sympathetic supply occurs in Horner's syndrome
Horner's syndrome
Horner's syndrome is the combination of drooping of the eyelid and constriction of the pupil , sometimes accompanied by decreased sweating of the face on the same side; redness of the conjunctiva of the eye is often also present...
, and presents as a partial ptosis.