Dominic Stone
The human eye has six extrinsic eye muscles, also called extraocular muscles, which are attached to the outside of the eyeball. These muscles are responsible for controlling eye movement and eye alignment. They are different from the intrinsic eye muscles, which are located within the eye and enable the eye to focus on nearby objects and control the amount of light entering the eye. The six extrinsic eye muscles can be divided into two groups: the four recti muscles and the two oblique muscles. These muscles work together to move the eye in various directions, including side to side, up and down, and diagonally, as well as controlling its rotation.
| Characteristics | Values |
|---|---|
| Number of extrinsic eye muscles | 6 or 7 |
| Types of extrinsic eye muscles | Recti muscles, superior oblique muscle, inferior oblique muscle, levator palpebrae superioris |
| Function | Control eye movement and eye alignment |
| Innervation | Cranial nerves III, IV, and VI |
| Origin | Recti muscles: Common tendinous ring; Superior oblique muscle: Back of the orbit; Inferior oblique muscle: Lower front of the nasal orbital wall |
| Insertion | Recti muscles: Anterior half of the eye; Superior oblique muscle: Top of the eyeball behind the superior rectus; Inferior oblique muscle: Under the lateral rectus muscle on the lateral, posterior part of the globe |
Explore related products
What You'll Learn
There are six extrinsic eye muscles that control eye movement
The human eye is an incredibly complex organ, with several components working together to enable vision. Extrinsic eye muscles, also known as extraocular muscles, are attached to the outside of the eyeball and control eye movement and eye alignment. There are six extrinsic eye muscles that work together to move the eye from side to side, up and down, and control its rotation. These six muscles are:
- Superior rectus
- Inferior rectus
- Lateral rectus
- Medial rectus
- Superior oblique
- Inferior oblique
The first four muscles listed above are recti muscles, which means they are "straight" muscles. The superior rectus is found at the top of the eye and controls upward movement. The inferior rectus is located at the bottom and allows the eye to move downward. The lateral rectus and medial rectus muscles work together in what is known as "antagonistic muscles". This means that the contraction of one leads to the inhibition of the other. The medial rectus is the muscle closest to the nose and moves the eye inward.
The remaining two muscles are oblique muscles, which take an angular approach to the eyeball. The superior oblique muscle works like a pulley, starting at the upper back of the eye and extending forward, then threading through a small bony opening on the upper-inner side of the eye socket called the trochlea. The inferior oblique attaches to the lower-inner side of the eye socket. It pulls the eye upward and laterally.
These six extrinsic eye muscles are innervated by three cranial nerves: the oculomotor nerve (CN III), the trochlear nerve (CN IV), and the abducens nerve (CN VI). Each nerve controls the movement of specific muscles. For example, the oculomotor nerve controls the superior, inferior, and medial rectus muscles, as well as the inferior oblique muscle. The trochlear nerve controls the superior oblique muscle, and the abducens nerve controls the lateral rectus muscle.
Building Muscle: Unlocking the Science of Strength Training
You may want to see also
Explore related products
One extrinsic eye muscle controls eyelid elevation
The extraocular muscles, or extrinsic ocular muscles, are the seven extrinsic muscles of the eye in humans and other animals. Six of these muscles control eye movement, while the seventh, the levator palpebrae superioris, controls eyelid elevation.
The levator palpebrae superioris (LPS) is the only muscle involved in raising the superior eyelid. It is innervated by the oculomotor nerve (CN III). The superior tarsal muscle, located within the LPS, is innervated by the sympathetic nervous system. The oculomotor nerve controls all muscles of the eye except for the superior oblique muscle, which is controlled by the trochlear nerve (CN IV), and the lateral rectus muscle, which is controlled by the abducens nerve (CN VI).
The six muscles responsible for eye movement are the four recti muscles and the two oblique muscles. The four recti muscles are the superior rectus, inferior rectus, medial rectus, and lateral rectus. These muscles originate from the common tendinous ring, a ring of fibrous tissue that surrounds the optic canal at the back of the orbit. From their origin, the muscles pass anteriorly to attach to the sclera of the eyeball. The name recti is derived from the Latin for "straight," representing the direct path from origin to attachment.
The two oblique muscles are the superior and inferior obliques. Unlike the recti group of muscles, the oblique muscles do not originate from the common tendinous ring. Instead, they take an angular approach to the eyeball, attaching to the posterior surface of the sclera.
Damage to the oculomotor nerve (CN III) can cause eyelid drooping (ptosis) and double vision (diplopia). Lesions may lead to an inability to open the eye due to paralysis of the levator palpebrae superioris muscle. This can result in a compensatory head tilt to alleviate symptoms.
Muscle Tension and Stress: What's the Connection?
You may want to see also
Explore related products
Four rectus muscles are involved
The extraocular muscles are located within the orbit but are extrinsic and separate from the eyeball itself. They control the movements of the eyeball and the superior eyelid. There are six muscles involved in the control of the eyeball itself, four rectus muscles and two oblique muscles. The four rectus muscles are the superior rectus, inferior rectus, medial rectus, and lateral rectus. Each of these rectus muscles has a distinct function.
The superior rectus is the primary elevator of the eye, with secondary actions of incyclotorsion and adduction. The name "superior" indicates that it is located at the top. During abduction, this muscle is responsible for elevation. It originates from the upper part of the common tendinous ring and attaches to the superior and anterior aspect of the sclera.
The inferior rectus is the primary depressor of the eye, with secondary actions of excyclotorsion and adduction. "Inferior" means that it is located at the bottom. During abduction, this muscle is responsible for depression. It originates from the common tendinous ring and attaches to the anterior, inferior surface of the eye.
The medial rectus is the primary adductor of the eye. It is one of the thickest of the extraocular muscles, possibly due to its frequent engagement in convergence tasks. "Medial" indicates that it is located on the side closest to the nose. It originates from the common tendinous ring and attaches to the sclera of the eyeball.
The lateral rectus is the primary abductor of the eye. It is innervated by the abducens nerve (CN VI). "Lateral" means that it is located on the side farthest from the nose. It originates from the annulus of Zinn, a tendinous ring at the apex of the orbit, and inserts into the sclera of the eye.
The four rectus muscles form the muscle cone within the orbit, with the apex of the cone being the annulus of Zinn, their point of origin. They get inserted into the sclera at varying distances, with the medial rectus inserting closest to the limbus, followed by the inferior rectus, lateral rectus, and superior rectus.
Diagnosing Muscle Tears: What You Need to Know
You may want to see also
Explore related products
![Practical Work on the Extrinsic Muscles of the Eye : for Optometrists / [E.] Occhiena, [R.C.] Schergens 1917 [Leather Bound]](https://m.media-amazon.com/images/I/617DLHXyzlL._AC_UL320_.jpg)
Two oblique muscles are involved
The extrinsic eye muscles, also known as the extraocular muscles, are located within the orbit but are extrinsic and separate from the eyeball itself. There are six muscles involved in the control of the eyeball, which can be divided into two groups: the four recti muscles and the two oblique muscles.
The two oblique muscles are the superior oblique and the inferior oblique. The superior oblique muscle works like a pulley, starting at the upper back of the eye and extending forward, then threading through a small bony opening on the upper-inner side of the eye socket called the trochlea. After it passes through the trochlea, it attaches to the top of the eyeball just behind the superior rectus. The inferior oblique attaches to the lower-inner side of the eye socket. Unlike the recti group of muscles, the oblique muscles do not originate from the common tendinous ring. Instead, they take an angular approach to the eyeball, attaching to the posterior surface of the sclera.
The oblique muscles are responsible for slight elevation and depression of the eyes, as well as slight rotation. For example, the superior oblique muscle will slightly depress the right eye, while the inferior oblique slightly elevates the left eye. The opposite occurs when looking to the left. This is the primary function of the oblique muscles, but they also slightly rotate the eyes, turning the “twelve o’clock pole” of each eye slightly toward or away from the nose.
The oblique muscles are innervated by two of the three cranial nerves that control the extraocular muscles: the trochlear nerve (CN IV) and the oculomotor nerve (CN III).
Ham: Exploring the Pig Muscle Delicacy
You may want to see also
Explore related products
The recti muscles have a direct path from origin to attachment
The recti muscles, also known as the extraocular muscles, are responsible for eye movement. Each eye has four rectus muscles: superior rectus, inferior rectus, medial rectus, and lateral rectus. These muscles originate from the common tendinous ring, a ring of fibrous tissue that surrounds the optic canal at the back of the orbit. From their origin, the muscles pass anteriorly to attach to the sclera of the eyeball. The name "recti" is derived from the Latin word for "straight," which represents the fact that these muscles follow a direct path from origin to attachment. This is in contrast to the oblique muscles, which take an angular approach to the eyeball.
The superior rectus muscle is responsible for intorsion, adduction, and elevation of the eye. It inserts on the anterior, superior surface of the eye and originates from the annulus of Zinn. The inferior rectus muscle is responsible for extorsion, adduction, and depression. It inserts on the anterior, inferior surface of the eye and also originates from the annulus of Zinn. The lateral rectus muscle is responsible for abduction.
The recti muscles are innervated by three cranial nerves: the oculomotor nerve (CN III), the trochlear nerve (CN IV), and the abducens nerve (CN VI). The oculomotor nerve controls the movements of the superior, inferior, and medial rectus muscles, as well as the inferior oblique muscle. The trochlear nerve controls the superior oblique muscle, while the abducens nerve controls the lateral rectus muscle.
Damage to one of these cranial nerves can cause paralysis of the respective muscles, altering the resting gaze of the affected eye. For example, a lesion of the oculomotor nerve can lead to the affected eye being displaced laterally by the lateral rectus and inferiorly by the superior oblique, resulting in a position known as "down and out." Similarly, a lesion of the trochlear nerve will paralyse the superior oblique muscle, causing diplopia (double vision).
Visceral Muscle Structure: Striated or Not?
You may want to see also
Frequently asked questions
The extrinsic eye muscles, also called extraocular muscles, are attached to the outside of the eyeball. They are found within the orbit of the eye but not in the eyeball itself.
There are six extrinsic eye muscles.
The six extrinsic eye muscles are made up of four recti muscles and two oblique muscles. The recti muscles are the superior rectus, inferior rectus, medial rectus, and lateral rectus. The oblique muscles are the superior oblique and inferior oblique.
The extrinsic eye muscles control eye movement and eye alignment. They work together to move the eye from side to side, up and down, and control its rotation.
The intrinsic eye muscles are located in the eye itself, while the extrinsic eye muscles are around the outside of the eye. The intrinsic muscles are involuntary and enable the eye to focus on near objects and control how much light enters the eye.
