What is the lateral rectus muscle?
The lateral rectus muscle is a muscle on the lateral side of the eye in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifically abduction.
What does the lateral rectus do in the eye?
Lateral rectus muscle (Musculus rectus lateralis) Lateral rectus muscle is one of the 4 straight muscles of the orbit responsible for the movement of the eye in the cardinal directions. These muscles, along with the superior and inferior oblique muscles, belong to the extraocular muscles of the eye.
Why does the abducens nerve innervate only the lateral rectus?
Since the abducens nerve only innervates the lateral rectus, other extraocular muscles will not be affected. Therefore, the muscle that is functionally antagonistic to the lateral rectus will overpower it and pull the eyeball on their side.
What happens if the lateral rectus muscle is paralyzed?
The lateral rectus muscle will be denervated and paralyzed and the patient will be unable to abduct the eye. For example, if the left abducens nerve is damaged, the left eye will not abduct fully.
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Which muscle is called muscle of marriage?
Sartorius muscleOriginAnterior superior iliac spine of the pelvic boneInsertionanteromedial surface of the proximal tibia in the pes anserinusArteryfemoral arteryNervefemoral nerve (sometimes from the intermediate cutaneous nerve of thigh)9 more rows
What does lateral rectus muscle mean?
The lateral rectus is a flat-shaped muscle, and it is wider in its anterior part. The lateral rectus muscle is an abductor and moves the eye laterally, and side to side along with the medial rectus, which is an adductor.
Is lateral rectus smooth muscle?
The lateral rectus muscle is a muscle on the lateral side of the eye in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifically abduction....Lateral rectus muscle.Lateral rectusFMA49038Anatomical terms of muscle11 more rows
What is medial and lateral rectus muscles?
Structure and Function The medial rectus is an adductor, and functions along with the lateral rectus which abducts the eye. These two muscles allow the eyes to move from side to side.
Which eye muscle is a lateral muscle?
lateral rectus muscleThe lateral rectus muscle is one of the 4 straight muscles of the orbit responsible for the movement of the eye in the cardinal directions....Lateral rectus muscle.OriginCommon tendinous ring (Annulus of Zinn)InsertionAnterior half of eyeball (posterior to corneoscleral junction)ActionAbducts eyeball2 more rows•May 11, 2020
Why is cranial nerve 6 palsy most common?
The most common causes of sixth cranial nerve palsy are stroke, trauma, viral illness, brain tumor, inflammation, infection, migraine headache and elevated pressure inside the brain. The condition can be present at birth; however, the most common cause in children is trauma.
What is the eye muscle called?
There are six extraocular muscles that move the globe (eyeball). These muscles are named the superior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, and inferior oblique.
How can you distinguish between medial and lateral rectus?
The lateral rectus (LR) is flat muscle located alongside the lateral wall of the orbit. The sixth cranial (abducens) nerve provides innervation of the muscle. The medial rectus (MR) is located alongside the medial wall of the orbit.
Is the lateral rectus muscle horizontal or vertical?
HorizontalHorizontal movements are controlled entirely by the medial and lateral rectus muscles; the medial rectus muscle is responsible for adduction, the lateral rectus muscle for abduction. Vertical movements require the coordinated action of the superior and inferior rectus muscles, as well as the oblique muscles.
Which muscle is antagonistic to the lateral rectus muscle?
Agonistic and antagonistic muscles For example, in abduction of the right eye, the right lateral rectus muscle is the agonist; the right superior and inferior oblique muscles are the synergists; and the right medial, superior, and inferior recti are the antagonists.
How long is the lateral rectus muscle?
The insertion parallels that of the medial rectus and is approximately 6.9 mm from the limbus, and the length of the tendon is approximately 8.8 mm.
What is the lateral rectus?
The lateral rectus is on the right side of the image. Figure showing the mode of innervation of the Recti medialis and lateralis of the eye. The lateral rectus muscle is a muscle on the lateral side of the eyeball in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible ...
What is the disorder of the lateral rectus muscle?
In addition, another disorder associated with the lateral rectus muscle is Duane Syndrome. This syndrome occurs when the sixth cranial nerve which controls the lateral rectus muscle does not develop properly.
What causes the abducens nerve to be damaged?
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, tumors, and lesions along the nerve at any point between the pons and lateral rectus muscle in orbit.
What is the sixth nerve palsy?
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, tumor, 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, tumors, 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 lateral rectus muscle will be denervated and paralyzed and the patient will be unable to abduct the eye. For example, if the left abducens nerve is damaged, the left eye will not abduct fully. While attempting to look straight ahead, the left eye will be deviated medially towards the nose due to the unopposed action of the medial rectus of the eye. Proper function of the lateral rectus is tested clinically by asking the patient to look laterally. Depending on the underlying cause of the lateral rectus palsy, some improvement may occur naturally over time. While the prognosis for a lateral rectus palsy onset by a viral illness is generally positive, the prognosis for an onset of trauma or tumor is quite poor. Ultimately, nerves are not very good at regenerating or healing themselves, so if the damage is severe there will be permanent damage.
Why is my left eye deviated towards the nose?
While attempting to look straight ahead, the left eye will be deviated medially towards the nose due to the unopposed action of the medial rectus of the eye. Proper function of the lateral rectus is tested clinically by asking the patient to look laterally.
Which nerve exits the pontomedullary junction of the brainstem?
These neurons project axons as the abducens nerve which exit from the pontomedullary junction of the brainstem, travels through the cavernous sinus and enter the orbit through the superior orbital fissure. It then enters the medial surface of the lateral rectus to innervate it.
Where is the lateral rectus located?
The lateral rectus originates at the lateral part of the annulus of Zinn, also known as the annular tendon or common tendinous ring, and inserts into the temporal side of the eyeball. The annulus of Zinn is a tendinous ring that surrounds the optic nerve and serves as the origin for five of the six extraocular muscles, ...
Which nerve innervates the lateral rectus muscle?
The abducens nerve innervates the lateral rectus muscle, providing it a neural pathway to the brain. The abducens is also known as the sixth cranial nerve. This nerve innervates some of the other muscles in the eye’s orbit.
What muscle moves the pupil away from the body's midline?
Lateral rectus. In the orbit of the eye, also called the eye socket, the lateral rectus muscle helps move the pupil away from the body’s midline. The muscle inserts into the temporal (outer) side of the eyeball and stretches to the annulus of Zinn, a tendinous ring circling the optic nerve. This occurs at the apex (back) of the orbit.
Can the abducens nerve cause double vision?
Should the abducens nerve cease to function properly, double vision could develop, as the medial rectus would begin to work unopposed. If the lateral rectus muscle itself sustains damage, a person’s eyesight could suffer as a result. However, this is also true if any eye muscles cease to function properly. Last medically reviewed on January 19, ...
Where does the lateral rectus muscle originate?
The lateral rectus muscle has its origin on both limbs of the common tendinous ring and the spina recti lateralis, a prominence on the greater wing of the sphenoid bone. The lateral rectus muscle parallels the lateral orbital wall until it passes through a connective tissue pulley just posterior to the equator of the globe; at this point it follows the curve of the globe to its insertion. 34,35 The insertion parallels that of the medial rectus and is approximately 6.9 mm from the limbus, and the length of the tendon is approximately 8.8 mm. 5
Which muscle innervates the lateral rectus?
CN VI innervates the lateral rectus muscle; damage results in ipsilateral paralysis of lateral gaze. CN IV innervates the superior oblique muscle; damage results in inability to look in and down (most conspicuous when climbing stairs, stepping off a curb, reading in bed). CN III (oculomotor nuclei) innervates the medial rectus, superior rectus, inferior rectus, and inferior oblique muscles (damage results in paralysis of the ipsilateral medial gaze) and also innervates the levator palpebrae superioris muscle (damage results in profound ptosis). The ciliary ganglion gives rise to postganglionic parasympathetic axons that supply the pupillary constrictor muscle and the ciliary muscle; damage results in a fixed and dilated pupil that does not constrict for the pupillary light reflex and does not accommodate to near vision.
What nerves are involved in the lateral rectus?
The abducens (sixth) nerve supplies the lateral rectus muscle. Selective involvement of the abducens nerve anywhere along its pathway leads to isolated weakness of abduction of the affected eye. Destruction of the abducens nucleus in the brain stem results in a conjugate gaze paralysis (ipsilateral) because, in addition to oculomotor neurons, the nucleus contains interneurons destined for the contralateral medial rectus nucleus. The trochlear (fourth) nerve supplies the contralateral superior oblique muscle, which turns in and depresses the eye. Patients with superior oblique weakness note an increase in diplopia with head tilt toward the side of weakness and often tilt their head in the opposite direction. At rest, there is slight upward deviation of the involved eye, and downward movement is impaired when the affected eye is turned in. Patients typically complain of diplopia when reading or going down stairs. The third (oculomotor) cranial nerve supplies the remaining ocular muscles. Involvement of the third nerve nucleus in the midbrain always produces at least some bilateral oculomotor weakness; the superior rectus division of the nucleus supplies the contralateral superior rectus muscle (all other divisions supply ipsilateral muscles). Peripheral third nerve paralysis can result from lesions damaging the structure anywhere from its course within the ventral midbrain to where it enters the orbit through the superior orbital fissure. When complete, third nerve palsy produces a widely dilated pupil, severe ptosis, and an externally deviated eye held in position by unopposed contraction of the lateral rectus muscle. In such conditions, the continued trochlear action reveals itself by intorsion of the eye when the subject attempts to look down.
What nerve innervates the lateral rectus muscle of the eye?
The abducens nerve innervates the lateral rectus muscle of the eye. It is responsible for lateral eye movements. Injury to this nerve prevents such movement. Injury to this nerve can cause double vision. Owing to its lengthy nature, multiple areas of the nerve have the potential to be damaged, whether at its nucleus or along cranial bone areas. It is difficult to locate the area of damage. But if this nerve is damaged, other cranial nerves are frequently also injured.18 Injury to this nerve occurs at a rate of 0.4%–4.1%. 21
What are the six ocular muscles?
The six ocular muscles—superior, inferior, medial, and lateral recti and superior and inferior obliques—are responsible for movements of the globe ( Fig. 1-7 ). Cranial nerve VI innervates the lateral rectus, which abducts (turns out) the eye. Cranial nerve IV innervates the superior oblique, which abducts, depresses, and intorts (rotates in) the eye. Cranial nerve III innervates the medial rectus, inferior rectus, superior rectus, and inferior oblique muscles. The medial rectus adducts (turns in) the eye, the inferior rectus depresses the eye, the superior rectus elevates the eye, and the inferior oblique abducts, elevates, and extorts (rotates out) the eye. Cranial nerve III also innervates the levator muscle, which is responsible for lid elevation. (The cardinal movements of the eye are shown in Fig. 1-8 .)
Which axons are innervated by the abducens and oculomotor nucle
requires the coordinated action of the lateral and medial rectus muscles, which are innervated by the abducens and oculomotor nuclei (medial rectus subdivision), respectively. The afferent limb of the H-VOR is conveyed by the horizontal semicircular canal ampullary nerves. These axons form monosynaptic excitatory contacts with cells in the ipsilateral MVN and vLVN ( McCrea et al., 1987a,b ), which in turn send glycinergic inhibitory ipsilateral projections and excitatory glutamatergic contralateral inputs to abducens motor and internuclear neurons ( Spencer and Baker, 1992 ). Medial rectus motoneurons in the oculomotor complex receive the monosynaptic excitatory input from ipsilateral vLVN via the ascending tract of Deiters (ATD) ( Muskens, 1913; Gacek, 1971 ), and the disynaptic excitatory input from the contralateral abducens internuclear neurons via the ascending MLF ( Highstein and Ito, 1971 ). The ipsilateral projection from vLVN to the oculomotor complex carried in ATD constitutes a notable exception to the overall VOR connectivity scheme which otherwise embodies inhibitory ipsilateral and excitatory contralateral projections The ATD conveys projections to medial rectus motoneurons, and also includes a contingent of fibers, probably from a separate vLVN neuronal population, that continues rostrally to terminate in the thalamus ( Highstein and Holstein, 2006 ).
Does BUP work in atrophic lateral rectus?
BUP did not work in five patients with atrophic lateral rectus muscles after sixth nerve paralysis. Some of these EOMs were injected several times, attempting to “grow” a bigger and stronger muscle. All patients remained without substantial change. We suggest that the absence of satellite cells around these atrophic muscles is the reason for this lack of response. Direct injection of stimulating molecules such as MGF may yet be useful in these muscles, as may be transplantation of muscle cells with BUP or transplantation of stem cells. The great need for a technique to strengthen weak EOM will attract several solutions beyond BUP.
What is the action of the lateral rectus?
Action. The action of the lateral rectus is to abduct the eye (see figure 1) 1. Unlike most of the other extraocular muscles, it has no significant contribution to movement in the other ocular axes.
Where is the lateral rectus?
Lateral rectus runs anteriorly on the medial surface of the eye and inserts into the lateral surface of the sclera just posterior to the junction of cornea and sclera 2.
What does the rectus mean?
Rectus comes from the Latin rectos, meaning straight 1. oculomotor nerve palsy. as 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. abducens nerve palsy.
Which muscle is responsible for abduction?
The lateral rectus muscle is one of the six extraocular muscles that control eye movements. It is responsible for abduction and is the only muscle that is innervated by the abducens nerve (CN VI).
Which nerve is the primary ocular abductor?
abducens nerve palsy. as the lateral rectus is the primary ocular abductor, abducens nerve palsy results in adduction of the affected eye, due to unopposed effect primarily of the medial rectus muscle.
Why is the medial rectus muscle weak?
Weakness of the medial rectus muscle can happen for five reasons; Oculomotor nerve palsy and/ or oculomotor nucleus injury (e.g. cavernous sinus thrombosis or cerebral infarction)
What is the function of the medial rectus muscle?
Function. When contracting, each medial rectus muscle adducts the eyeball, i.e. pulls the eye medially. This action is important in two types of ocular movements; conjugate and disconjugate. Conjugate movements are when both eyeballs move in the same direction.
What is the movement of the eyeballs that converge toward the midline?
Disconjugate movements are when the eyeballs converge or diverge from the midline. When both medial recti contract, they converge the eyeballs toward the midline. Convergence is a part of the accommodation reflex, when the eyes adjust to observe a close object.
What muscles move the eye?
Medial rectus is one of the six extraocular muscles located in the orbit. Attaching between the bony walls of the orbit and the eyeball, these muscles serve to synchronously move the eyes. Besides medial rectus, this group of muscles also gathers the superior rectus , inferior rectus, lateral rectus, superior oblique and inferior oblique muscles. Notice how these muscles are divided into four recti and two oblique muscles. The former move the eyes in the four cardinal directions, while the latter adjust the position of the eyeball depending on the position of the head.
What are the symptoms of medial rectus palsy?
thyroid ophthalmopathy as part of Graves disease) Typical signs and symptoms of medial rectus palsy are divergent strabismus and consequential diplopia. Treatment is based on discovering the cause of the palsy and treating it.
How many recti and oblique muscles are there?
Notice how these muscles are divided into four recti and two oblique muscles. The former move the eyes in the four cardinal directions, while the latter adjust the position of the eyeball depending on the position of the head.
Which nerve is responsible for pulling the contralateral eye toward the desired direction?
This sequence pulls the contralateral eye toward the desired direction. As lateral rectus is supplied by the abducens nerve (CN VI), the synchrony between these muscles is established by the medial longitudinal fasciculus that connects the oculomotor and abducens nuclei.
