The levator palpebrae superioris () is the
muscle
Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
in the
orbit
In celestial mechanics, an orbit (also known as orbital revolution) 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 ...
that elevates the upper
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. "Palpebral ...
.
Structure
The levator palpebrae superioris originates from inferior surface of the lesser wing of the
sphenoid bone
The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of occipital bone, basilar part of the occipital bone. The sphenoid bone is one of the seven bon ...
, just above the
optic foramen
The ''optic foramen'' is the opening to the optic canal. The canal is located in the sphenoid bone; it is bounded medially by the body of the sphenoid and laterally by the lesser wing of the sphenoid.
The superior surface of the sphenoid bone is ...
. It broadens and decreases in thickness (becomes thinner) 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 (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the somatic nervous system, voluntary muscular system and typically are a ...
. The
superior tarsal muscle
The superior tarsal muscle is a smooth muscle adjoining the levator palpebrae superioris muscle muscle that helps to raise the upper eyelid.
Structure
The superior tarsal muscle originates on the underside of levator palpebrae superioris m ...
, a smooth muscle, is attached to the levator palpebrae superioris, and inserts on the superior tarsal plate as well.
Blood supply
The levator palebrae superioris receives its blood supply from branches of the
ophthalmic artery
The ophthalmic artery (OA) is an artery of the head. It is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the ophthalmic artery supply all the structures in the orbit around the eye, as well as some ...
, specifically, muscular branches and the
supraorbital artery
The supraorbital artery is a branch of the ophthalmic artery. It passes anteriorly within the orbit to exit the orbit through the supraorbital foramen or notch alongside the supraorbital nerve, splitting into two terminal branches which go on to f ...
. Blood is drained into the
superior ophthalmic vein
The superior ophthalmic vein is a vein of the orbit that drains venous blood from structures of the upper orbit. It is formed by the union of the angular vein, and supraorbital vein. It passes backwards within the orbit alongside the ophthalmic a ...
.
Nerve supply
The levator palpebrae superioris receives motor innervation from the superior division of the
oculomotor nerve
The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements o ...
.
The smooth muscle that originates from its undersurface, called the
superior tarsal muscle
The superior tarsal muscle is a smooth muscle adjoining the levator palpebrae superioris muscle muscle that helps to raise the upper eyelid.
Structure
The superior tarsal muscle originates on the underside of levator palpebrae superioris m ...
is innervated by postganglionic sympathetic axons from the
superior cervical ganglion
The superior cervical ganglion (SCG) is the upper-most and largest of the cervical sympathetic ganglia of the sympathetic trunk. It probably formed by the union of four sympathetic ganglia of the cervical spinal nerves C1–C4. It is the only ...
.
Function
The levator palpebrae superioris elevates the upper eyelid.
Clinical significance
Damage to this muscle or its innervation can cause
ptosis, which is drooping of the eyelid.
Lesions in CN III can cause ptosis,
because without stimulation from the oculomotor nerve the levator palpebrae cannot oppose the force of gravity, and the eyelid droops.
Ptosis can also result from damage to the adjoining
superior tarsal muscle
The superior tarsal muscle is a smooth muscle adjoining the levator palpebrae superioris muscle muscle that helps to raise the upper eyelid.
Structure
The superior tarsal muscle originates on the underside of levator palpebrae superioris m ...
or its sympathetic innervation. Such damage to the sympathetic supply occurs in
Horner's syndrome
Horner's syndrome, also known as oculosympathetic paresis, is a combination of symptoms that arises when a group of nerves known as the sympathetic trunk is damaged. The signs and symptoms occur on the same side (ipsilateral) as it is a lesion ...
and presents as a partial ptosis. It is important to distinguish between these two very different causes of ptosis. This can usually be done clinically without issue, as each type of ptosis is accompanied by other distinct clinical findings.
The ptosis seen in paralysis of the levator palpebrae superioris is usually more pronounced than that seen due to paralysis of the superior tarsal muscle.
Additional images
File:Gray893.png, Sagittal section through the upper eyelid.
File:Trochlear and frontal nerves.jpg, Levator palpebrae superioris muscle
File:Slide16aa.JPG, Levator palpebrae superioris muscle
File:Slide1abaa.JPG, Extrinsic eye muscle. Nerves of orbita. Deep dissection.
File:Slide3abab.JPG, Extrinsic eye muscle. Nerves of orbita. Deep dissection.
See also
*
Blepharospasm
Blepharospasm is a neurological disorder characterized by intermittent, involuntary spasms and contractions of the orbicularis oculi muscle, orbicularis oculi (eyelid) muscles around both eyes. These result in abnormal twitching or blinking, an ...
*
Ptosis
*
Superior tarsal muscle
The superior tarsal muscle is a smooth muscle adjoining the levator palpebrae superioris muscle muscle that helps to raise the upper eyelid.
Structure
The superior tarsal muscle originates on the underside of levator palpebrae superioris m ...
References
External links
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{{Authority control
Muscles of the head and neck
Human eye anatomy