Name: eye muscles and how they focus
Uploaded: 2024-03-28T14:28:28.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.20

Muscles of the Eye

Chaque œil a six muscles extraoculaires, trois muscles intraoculaires involontaires et un muscle écarteur primaire de la paupière.
Quatre muscles extraoculaires – les muscles recti supérieur, inférieur, latéral et médial – proviennent d’un anneau tendineux commun qui entoure le foramen optique et s’insère sur la sclère.
Le muscle oblique supérieur prend naissance au-dessus du foramen optique, tandis que le muscle oblique inférieur prend naissance sur le maxillaire en dessous de l’orbite. Ces deux muscles s’insèrent latéralement sur la sclère.
Ensemble, ces six muscles coordonnent les mouvements du globe oculaire vers le haut, vers le bas, sur le côté et en diagonale.
De plus, le releveur des paupières supérieures, avec son origine dans l’aile de l’os sphénoïde et son insertion sur la paupière supérieure, agit comme le principal écarteur de la paupière, permettant un mouvement d’ouverture des yeux.
C’est un antagoniste du muscle facial, orbicularis oculi, qui facilite la fermeture ou la protraction des paupières.
Les trois muscles lisses intraoculaires comprennent le muscle ciliaire, les pupilles dilatatrices et les pupilles du sphincter.
Ces muscles contrôlent les mouvements du cristallin et de la pupille pour modifier la distance focale de l’œil afin d’adapter la vision.

muscles de l'œil

Les muscles de l’œil sont des structures sophistiquées qui contrôlent le mouvement et la concentration des yeux, permettant ainsi les ajustements précis et rapides nécessaires à la vision. L’œil humain est contrôlé par dix muscles : six muscles extraoculaires, trois muscles intraoculaires et un muscle rétracteur primaire de la paupière.

Muscles extraoculaires

Les six muscles extraoculaires entourent le globe oculaire et contrôlent ses mouvements. Ils sont responsables d’un large éventail de mouvements oculaires, notamment regarder vers le haut, le bas, la gauche, la droite et faire pivoter l’œil. Ceux-ci incluent le droit latéral, qui déplace l’œil vers l’extérieur, et le droit médial, qui l’amène vers l’intérieur vers le nez. Le droit supérieur et le droit inférieur élèvent et abaissent l'œil, respectivement, tandis que les muscles obliques supérieurs et obliques inférieurs font pivoter l'œil. Les quatre droits – supérieur, inférieur, latéral et médial – partent d’un anneau tendineux commun qui entoure le foramen optique et s’attache à la sclère. Cependant, le muscle oblique supérieur commence au-dessus du foramen optique, tandis que l'oblique inférieur commence au maxillaire sous l'orbite, et les deux muscles se connectent latéralement à la sclère. Ces muscles travaillent par paires synchronisées, permettant une concentration coordonnée et permettant des fonctions critiques comme la perception de la profondeur.

Muscles intraoculaires

Les muscles intraoculaires sont situés à l’intérieur de l’œil et sont responsables des ajustements internes. Le muscle ciliaire joue un rôle essentiel dans la focalisation de la vision en contrôlant la forme du cristallin ; il se contracte pour épaissir la lentille pour les objets proches et se détend pour la vision à distance. L'iris contient deux muscles : le muscle sphincter, qui resserre la pupille sous une lumière vive pour réduire l'entrée de lumière et protéger la rétine, et le muscle dilatateur, qui élargit la pupille dans des conditions de faible luminosité pour permettre à plus de lumière d'entrer, améliorant ainsi la vision.

Écarteur de paupière primaire

En dehors de ceux-ci, il existe un muscle appelé releveur de la paupière supérieure, qui prend sa source dans l'aile de l'os sphénoïde et s'attache à la paupière supérieure. Ce muscle est responsable de l’ouverture de l’œil. Il agit contre le muscle facial, orbiculaire oculi, responsable de la fermeture ou de la saillie de la paupière.

Muscles de l'œil

Les muscles de l’œil sont des structures sophistiquées qui contrôlent le mouvement et la mise au point de l’œil, permettant les ajustements précis et rapides nécessaires pour ...

Education

Enseignement

JoVE Core

Anatomy and Physiology

Anatomie et physiologie

Unit 1

Unité 1

The Muscular System

Le système musculaire

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

eye muscles and how they focus

The eye muscles control movement, focus, and eyelid opening. The human eye uses ten muscles: six extraocular muscles, three intraocular muscles, and one main eyelid retractor muscle.

The six extraocular muscles sit around the eyeball and move it in different directions. The lateral rectus pulls the eye outward, and the medial rectus turns it inward toward the nose. The superior rectus and inferior rectus move the eye up and down, while the superior oblique and inferior oblique rotate the eye. The four recti begin at a common tendinous ring that surrounds the optic foramen and attach to the sclera, the white outer layer of the eye. The superior oblique begins above the optic foramen, and the inferior oblique begins on the maxilla below the orbit. Both attach laterally to the sclera.

These muscles work in coordinated pairs. Their teamwork helps the eyes move smoothly and stay focused. This coordination also supports depth perception.

The intraocular muscles are inside the eye and make internal adjustments. The ciliary muscle changes the shape of the lens for focusing. It contracts to thicken the lens for nearby objects and relaxes for distance viewing. The iris also contains two muscles. The sphincter muscle narrows the pupil in bright light to reduce light entry and protect the retina. The dilator muscle widens the pupil in low light so more light can enter.

The levator palpebrae superioris is the main eyelid retractor muscle. It starts in the wing of the sphenoid bone and attaches to the upper eyelid. Its job is to open the eye. It works against the orbicularis oculi, the facial muscle that closes or protrudes the eyelid.

Eye Muscles and How They Focus

the muscular system

Muscles, Bones, and Body Movement

The muscular system helps the body move, stay stable, and carry out internal work. It includes three kinds of muscle tissue: skeletal, smooth, and cardiac muscle. Each type has a different role in the body. Skeletal muscles are under conscious control, so people can move them on purpose. They attach to bones by tendons, and their contraction and relaxation make actions like walking and lifting possible. These muscles also produce heat during physical activity, which helps maintain body...

fascicle arrangement in skeletal muscles

How Muscle Fiber Layout Shapes Movement

Skeletal muscle fascicles are bundles of muscle fibers, and their layout helps determine how a muscle moves. The way these fascicles are arranged affects both power and range of motion. Different arrangements give muscles different mechanical strengths. Parallel muscles have fascicles that run parallel to the long axis of the muscle. Common examples are the biceps brachii and the rectus abdominis. When these muscles contract, they shorten and become wider. They can shorten by about 30% of...

muscle coordination and action

Muscles That Work Together in Movement

Muscles work together to create smooth, purposeful movement. Actions such as flexion, extension, adduction, abduction, and rotation depend on this coordination. The body uses several muscles in a controlled way so joints and bones move as needed. Four functional roles help describe how muscles act during movement: agonist, antagonist, synergist, and fixator. An agonist, also called the prime mover, is the main muscle that produces a specific motion. During a bicep curl, the biceps brachii is...

naming skeletal muscles

How Muscles Get Their Names

Skeletal muscle names are built from features that help identify each muscle. The names of the roughly 700 muscles in the human body can point to where a muscle is found, what it looks like, or how it works. That makes the names easier to learn and remember. Many muscle names describe the region of the body. The temporalis muscle is in the head region, while the brachialis is in the arm. Other names describe position and depth. Muscles near the surface may be called externus or superficialis,...

axial and appendicular muscles

Muscles for Movement and Body Support

Skeletal muscles support movement and body structure. They are grouped into axial muscles and appendicular muscles based on where they are found and what they do. Axial muscles lie along the body’s midline. They connect with the axial skeleton, which includes the skull, spine, ribs, and sternum. These muscles help with facial expressions, head and neck movement, speaking, and eating. They also help control movement of the vertebral column with the back muscles. The trunk also contains...

muscles for facial expressions

How Facial Muscles Shape Expression

Facial muscles shape human expression by moving the skin of the face and scalp. These craniofacial muscles are thin skeletal muscles that lie just beneath the skin. They help create the nonverbal signals people use to show emotion and intention. There are about 20 of these muscles. Most begin on bones or fibrous parts of the skull and then extend outward to attach to the skin. They are called muscles of facial expression, or mimetic muscles, because they reflect feelings through movement. <br...

muscles of the eye

The eye muscles control movement, focus, and eyelid opening. The human eye uses ten muscles: six extraocular muscles, three intraocular muscles, and one main eyelid retractor muscle. The six extraocular muscles sit around the eyeball and move it in different directions. The lateral rectus pulls the eye outward, and the medial rectus turns it inward toward the nose. The superior rectus and inferior rectus move the eye up and down, while the superior oblique and inferior oblique rotate the eye.

muscles of the anterior neck

Anterior Neck Muscles by Region

The anterior neck muscles are grouped by where they sit in the front of the neck. They include superficial muscles, suprahyoid muscles, and infrahyoid muscles. This layout helps show how the neck muscles are organized around the hyoid bone. The superficial muscles are the most visible muscles in the front of the neck. They include the platysma and sternocleidomastoid, often called the SCM. The platysma is a broad, thin muscle that stretches from the chest and shoulders to the lower jaw and...

muscles that move the head

How Neck Muscles Guide Head Motion

Neck muscles guide head motion by working together to bend, turn, and lift the head. They help with rotation, flexion, extension, and lateral bending. The sternocleidomastoid, or SCM, plus the suprahyoid and infrahyoid muscles are major head flexors. The SCM runs from the sternum and clavicle to the mastoid process of the temporal bone. When both SCM muscles contract, they bend the head forward. When only one side contracts, it bends the head toward that side or turns the head to the opposite...

muscles of the vertebral column

How Back Muscles Support Spine Movement

Back muscles that lie deep to the thoracolumbar fascia are called intrinsic, or true, back muscles. They are grouped into four layers. These layers are the superficial, intermediate, deep, and deepest layers. The superficial layer mainly includes the splenius muscles. These are the splenius capitis and splenius cervicis. They help move the head and cervical spine by supporting extension, rotation, and lateral bending. The splenius capitis runs from the upper thoracic and lower cervical...

muscles of the thorax

How Thorax Muscles Drive Breathing

Thorax muscles help breathing and support movement in the upper body. They also help keep the chest stable. Together, these muscles make the rib cage move while the lungs fill and empty. The diaphragm is the main breathing muscle in the thorax. It is a wide, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. It starts below the rib cage and lumbar vertebrae and attaches to the central tendon. When it contracts, it flattens and moves downward. This increases the...

muscles of the abdomen

Abdominal Wall Muscles and Support

The abdominal wall muscles support the abdominal cavity and help protect the internal organs. This flexible wall is bordered by the xiphoid process and costal margins at the top, the vertebral column at the back, and the pelvic bones and inguinal ligament at the bottom. It is divided into the anterolateral region and the posterior region. The anterolateral region includes five paired muscles in two groups. The lateral group contains the external oblique, internal oblique, and transversus...

muscles of the pelvic floor and perineum

Pelvic Floor Muscles and Continence

The pelvic floor and perineal muscles support the pelvic organs and help control continence. They also play roles in sexual function, childbirth, and core stability. These muscles are usually divided into a superficial perineal layer and a deeper pelvic floor layer. The perineum is a diamond-shaped area below the pelvic diaphragm. It is split into an anterior urogenital triangle and a posterior anal triangle. The urogenital triangle contains the external genitals and includes the superficial...

muscles of the shoulder

Shoulder Girdle Muscles and Scapula Motion

Shoulder girdle muscles stabilize the clavicle and scapula, and that support helps the humerus move efficiently. Scapular movement also works with humerus movement and extends the arm’s range of motion. Raising the arm overhead depends on upward rotation of the scapula. The anterior thoracic muscles include the serratus anterior, subclavius, and pectoralis minor. The serratus anterior, often called the boxer’s muscle, starts on the first to eighth or ninth ribs and inserts along the superior...

muscles that move the arm

Arm Muscles and Their Movements

Arm muscles move the humerus through flexion, extension, abduction, adduction, and rotation. Nine muscles help produce these arm movements. Two of them, the pectoralis major and latissimus dorsi, come from the axial skeleton. The other seven begin on the scapula and are called scapular muscles. The pectoralis major has two origins, or heads. Its clavicular head starts on the medial half of the clavicle. Its sternocostal head starts on the costal cartilages of ribs 1 through 6, the sternum, and...

muscles that move the forearm

Forearm Muscles for Elbow and Rotation

Forearm muscles help the arm bend, straighten, and rotate at the elbow and radioulnar joints. They are grouped as forearm flexors, forearm extensors, forearm pronators, and forearm supinators. The flexors and extensors act on the elbow joint. The pronators and supinators act on the radioulnar joints. The forearm flexors are the biceps brachii, brachialis, and brachioradialis. The biceps brachii has two heads. Its long head begins at the supraglenoid tubercle of the scapula, and its short head...

muscles of the forearm that move the hand and fingers

muscles-of-the-forearm-that-move-the-hand-and-fingers

Forearm Flexors, Extensors, and Wrist Support

The forearm muscles that move the wrist, hand, and fingers are grouped into anterior and posterior compartments. These muscles work together to bend, straighten, and stabilize the hand and digits. They also connect to the bones of the wrist and hand in organized layers. The anterior compartment contains the flexor muscles. These muscles usually start at the humerus and attach to the carpals, metacarpals, and phalanges. The superficial layer includes the flexor carpi radialis, palmaris longus,...

muscles that move the thigh

Hip Muscles That Move the Thigh

Hip muscles control thigh movement by connecting the pelvic girdle to the femur. The iliopsoas is one key muscle group. It is made of the psoas major and iliacus muscles. Both share a common insertion on the lesser trochanter of the femur. The gluteal muscles also play major roles. The gluteus maximus starts on the posterior ilium, sacrum, coccyx, and thoracolumbar fascia. It inserts on the iliotibial tract and the gluteal tuberosity of the femur. This muscle is the chief extensor of the femur.

muscles that move the leg

Thigh Muscles Behind Leg Motion

Thigh muscles help move the leg through flexion, extension, adduction, and rotation. They are grouped into the anterior, medial, and posterior compartments of the thigh. Each group supports a different part of leg motion at the hip and knee. The anterior compartment includes the quadriceps femoris, the most visible thigh muscle group. It helps extend the leg and flex the thigh. The quadriceps is made of four muscles: vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris.

muscles of the leg that move the foot and toes

muscles-of-the-leg-that-move-the-foot-and-toes

Leg Muscle Groups for Foot Motion

The leg muscles that move the foot and toes are organized into the anterior, lateral, and posterior compartments. Each compartment has a distinct set of muscles with its own actions. Together, they control dorsiflexion, plantar flexion, inversion, eversion, and toe movement. The anterior compartment includes the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and fibularis tertius. The tibialis anterior runs along the lateral surface of the tibia, is easy to feel, and...

key terms and concepts

Learn how the extraocular, intraocular, and eyelid muscles move the eye, change lens shape, and adjust pupil size for clear vision.

Eye Muscles and How They Focus | JoVE K12

anatomy and physiology

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Eye Muscles and How They Focus

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