Victor Forge
The human body has seven extraocular muscles, which are the most specialised skeletal muscles. These muscles are divided into two groups: the four rectus muscles and the two oblique muscles. The seventh muscle, the levator palpebrae superioris, is separate from the other six. These muscles are responsible for controlling the movements of the eyeball and the superior eyelid.
| Characteristics | Values |
|---|---|
| Number of extraocular muscles | 7 |
| Number of rectus muscles | 4 |
| Number of oblique muscles | 2 |
| Number of levator palpebrae superioris muscles | 1 |
| Names of rectus muscles | Medial rectus, lateral rectus, superior rectus, inferior rectus |
| Names of oblique muscles | Superior oblique, inferior oblique |
| Name of levator palpebrae superioris muscle | Levator palpebrae superioris |
| Function of rectus and oblique muscles | Eye movement |
| Function of levator palpebrae superioris muscle | Eyelid movement |
Explore related products
What You'll Learn
There are seven extraocular muscles
The four rectus muscles are the superior, inferior, medial, and lateral rectus. The two oblique muscles are the superior and inferior obliques. The levator palpebrae superioris is responsible for eyelid elevation.
The rectus and oblique muscles are responsible for eye movement, while the levator palpebrae superioris is responsible for superior eyelid movement. These muscles allow the eyes to move into different gazes, and are important for binocular single vision.
While there are seven extraocular muscles, one source mentions six extraocular muscles. However, it is unclear whether this source is referring to the same muscles.
Muscle Mass and BMI: What's the Real Effect?
You may want to see also
Explore related products
Four rectus muscles
There are four rectus muscles: the superior, inferior, medial, and lateral rectus. These are four of the seven extraocular muscles, which are the most specialised skeletal muscles in the human body. They are divided into two groups: the recti and oblique muscles, which are responsible for eye movement, and the levator palpebrae superioris, which is responsible for superior eyelid movement.
The rectus muscles are responsible for the movement of the eyes into different gazes. The superior rectus muscle is located at the top of the eye, while the inferior rectus is at the bottom. The medial rectus is the largest of the extraocular movement muscles and is located on the inner side of the eye. It controls movement towards the body's midline. The lateral rectus is responsible for abduction, or movement away from the body's midline.
The four rectus muscles work together with the two oblique muscles to move the eyes into different gazes. With the head facing straight and the eyes facing straight ahead, the eyes are said to be in primary gaze. From this position, an action from an extraocular muscle produces a secondary or tertiary gaze. Although the globe can be moved about 50 degrees from the primary position, usually during normal eye movement, only 15 degrees of extraocular muscle movement occurs before head movement begins.
Understanding Sphincter Muscle Constriction: A Guide
You may want to see also
Explore related products
Two oblique muscles
There are seven extraocular muscles, four of which are rectus muscles, two are oblique muscles, and one is the levator palpebrae superioris. The two oblique muscles are the superior oblique and inferior oblique. These muscles are responsible for the movement of the eyes into different gazes. The superior oblique muscle is located in the upper part of the eye and is responsible for depressing, abducting, and internally rotating the eye. The inferior oblique muscle is located in the lower part of the eye and is responsible for elevating, abducting, and externally rotating the eye. Both muscles work together to help the eye move in a coordinated manner and allow for a full range of motion. The oblique muscles are important for maintaining proper eye alignment and ensuring that the eyes work together as a team. Any weakness or imbalance in these muscles can lead to conditions such as strabismus, where the eyes are not properly aligned and can cause double vision.
Acupuncture's Muscle-Relaxing Powers: Ancient Technique, Modern Science
You may want to see also
Explore related products
The levator palpebrae superioris is responsible for eyelid elevation
There are seven extraocular muscles, four rectus muscles, two oblique muscles, and the levator palpebrae superioris. The levator palpebrae superioris is responsible for eyelid elevation. It is a skeletal muscle of the face that lifts the upper eyelid. It originates from the inferior surface of the lesser wing of the sphenoid bone, just above the optic foramen. It broadens and decreases in thickness and becomes the levator aponeurosis. This portion inserts on the skin of the upper eyelid, as well as the superior tarsal plate.
The levator palpebrae superioris is an extraocular muscle that indirectly facilitates movements of the eye by elevating and retracting the upper eyelid and allowing an unhindered upward gaze. It is a facial muscle that contributes to the array of facial expressions since the upper lid elevation contributes to expressing feelings of fear, anger and shock.
The levator palpebrae superioris is also known as the 'elevating muscle of the upper eyelid'. It is a triangular muscle that extends along the roof of the orbit, from the apex of the orbit to the superior eyelid. It originates with a short and narrow tendon from the inferior aspect of the lesser wing of the sphenoid bone, superior and anterior to the common tendinous ring.
Damage to the levator palpebrae superioris or its innervation can cause ptosis, which is drooping of the eyelid. Ptosis may also be indicative of sympathetic nerve damage in nearby muscles, including the superior tarsal muscle.
Muscle Atrophy: Understanding the Science of Shrinking Muscles
You may want to see also
Explore related products
![RENPHO Eyeris Shift Eye Massager for Migraines [2025 Upgraded], Heated Eye Massager & Sleep Mask for Relaxation, Birthday Gifts for Women/Men/Mom/Dad, Music Temple Fack Mask Massager, Improve Sleep](https://m.media-amazon.com/images/I/610wR-DflgL._AC_UL320_.jpg)
The lateral rectus is responsible for abduction
There are seven extraocular muscles, four rectus muscles, two oblique muscles, and the levator palpebrae superioris. The four rectus muscles are the superior, inferior, medial, and lateral rectus. The lateral rectus is responsible for abduction, which is the movement of the eye away from the nose. It is the only muscle that is innervated by the abducens nerve (CN VI). The lateral rectus muscle runs anteriorly on the lateral surface of the eye and inserts into the lateral surface of the sclera just posterior to the junction of cornea and sclera.
The lateral rectus is unique among the extraocular muscles in being supplied by the abducens nerve. The abducens nerve palsy results in adduction of the affected eye, due to the unopposed effect of the medial rectus muscle. The medial rectus muscle is responsible for adduction, the movement of the eye towards the nose. The lateral rectus and superior oblique muscles are the only extraocular muscles not supplied by the oculomotor nerve. The unopposed force generated by these muscles results in depression and abduction of the affected eye.
The lateral rectus muscle is one of the six extraocular muscles that control eye movements. It is the primary ocular abductor. The lateral rectus, along with the other rectus muscles, arises from the annulus of Zinn, the common tendinous ring at the apex of the orbit that surrounds the optic canal. Branches of the ophthalmic artery, itself a branch of the internal carotid artery, supply the lateral rectus muscle.
A sixth nerve palsy, also known as abducens nerve palsy, is a neurological defect that results from a damaged or impaired abducens nerve. This damage can stem from stroke, trauma, tumour, inflammation, and infection. Damage to the abducens nerve by trauma can be caused by any type of trauma that causes elevated intracranial pressure, including hydrocephalus, traumatic brain injury with intracranial bleeding, tumours, and lesions along the nerve at any point between the pons and lateral rectus muscle in orbit. This defect can result in horizontal double vision and reduced lateral movement.
The Rapid Reality of Muscle Loss Explained
You may want to see also
Frequently asked questions
There are seven extraocular muscles.
The seven extraocular muscles are the levator palpebrae superioris, superior rectus, inferior rectus, medial rectus, lateral rectus, inferior oblique and superior oblique.
Four of the extraocular muscles are rectus muscles: the superior, inferior, medial, and lateral rectus.
Two of the extraocular muscles are oblique muscles: the superior and inferior obliques.
The extraocular muscles control the movements of the eye and eyelids, and are important for binocular single vision.
