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

Ogni occhio ha sei muscoli extraoculari, tre muscoli intraoculari involontari e un muscolo divaricatore palpebrale primario.
Quattro muscoli extraoculari - il retto superiore, inferiore, laterale e mediale - hanno origine su un anello tendineo comune che racchiude il forame ottico e si inserisce sulla sclera.
Il muscolo obliquo superiore ha origine sopra il forame ottico, mentre il muscolo obliquo inferiore ha origine sulla mascella sotto l'orbita. Entrambi questi muscoli si inseriscono lateralmente sulla sclera.
Insieme, questi sei muscoli coordinano i movimenti del bulbo oculare verso l'alto, verso il basso, lateralmente e diagonalmente.
Inoltre, l'elevatore della palpebra superiore, con la sua origine nell'ala dell'osso sfenoidale e l'inserzione sulla palpebra superiore, funge da divaricatore primario della palpebra, consentendo il movimento di apertura degli occhi.
È un antagonista del muscolo facciale, l'orbicolare dell'occhio, che facilita la chiusura o la protrazione delle palpebre.
I tre muscoli lisci intraoculari comprendono il muscolo ciliare, le pupille dilatatrici e le pupille dello sfintere.
Questi muscoli controllano i movimenti del cristallino e della pupilla per modificare la lunghezza focale dell'occhio per l'accomodazione della visione.

muscoli dell'occhio

I muscoli dell'occhio sono strutture sofisticate che controllano il movimento oculare e la messa a fuoco, consentendo gli aggiustamenti rapidi e precisi necessari per la vista. L'occhio umano è controllato da dieci muscoli: sei muscoli extraoculari, tre muscoli intraoculari e un muscolo retrattore della palpebra primario.

Muscoli extraoculari

I sei muscoli extraoculari circondano il bulbo oculare e ne controllano i movimenti. Sono responsabili di un’ampia gamma di movimenti oculari, tra cui guardare in alto, in basso, a sinistra, a destra e ruotare l’occhio. Questi includono il retto laterale, che muove l'occhio verso l'esterno, e il retto mediale, che lo porta verso il naso. Il retto superiore e il retto inferiore fanno alzare e abbassare rispettivamente l'occhio, mentre i muscoli obliquo superiore e inferiore ruotano l'occhio. I quattro retti, superiore, inferiore, laterale e mediale, partono da un anello tendineo comune che circonda il forame ottico e si attacca alla sclera. Tuttavia, il muscolo obliquo superiore inizia sopra il forame ottico, mentre l'obliquo inferiore inizia sulla mascella sotto l'orbita ed entrambi i muscoli si collegano lateralmente alla sclera. Questi muscoli lavorano in coppie sincronizzate, consentendo una messa a fuoco coordinata e abilitando funzioni critiche come la percezione della profondità.

Muscoli intraoculari

I muscoli intraoculari si trovano all'interno dell'occhio e sono responsabili degli aggiustamenti interni. Il muscolo ciliare svolge un ruolo fondamentale nella messa a fuoco della visione controllando la forma del cristallino; si contrae per ispessire il cristallino per gli oggetti vicini e si rilassa per la visione a distanza. L'iride contiene due muscoli: il muscolo sfintere, che restringe la pupilla in condizioni di luce intensa per ridurne l'ingresso e proteggere la retina; e il muscolo dilatatore, che allarga la pupilla in condizioni di scarsa illuminazione per consentire l'ingresso di più luce, migliorando la vista.

Retrattore della palpebra primario

Oltre a questi, esiste un muscolo chiamato elevatore della palpebra superiore, che ha origine nell'ala dell'osso sfenoide e si attacca alla palpebra superiore. Questo muscolo è responsabile dell'apertura dell'occhio. Agisce contro il muscolo facciale, il muscolo orbicolare dell'occhio , responsabile della chiusura o della sporgenza della palpebra.

Muscoli dell'occhio

I muscoli dell'occhio sono strutture sofisticate che controllano il movimento e la messa a fuoco degli occhi, consentendo le regolazioni precise e rapide necessarie per ...

Education

Didattica

JoVE Core

Anatomy and Physiology

Anatomia e Fisiologia

Unit 1

Unità 1

The Muscular System

Il sistema muscolare

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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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