Related Experiment Video
Updated: Jul 16, 2026
08:18
Three-Dimensional Reconstruction of Orbital Fractures
Published on: May 16, 2025
Mechanics of the orbita
1Jules Stein Eye Institute, Departments of Ophthalmology and Neurology, Neuroscience Bioengineering Interdepartmental Programs, David Geffen Medical School at the University of California, Los Angeles, CA 90095-7002, USA. jld@ucla.edu
Developments in Ophthalmology
|February 23, 2007
Summary
The eye
Area of Science:
- Ophthalmology
- Neuroscience
- Biomechanics
Background:
- Ocular motility was previously thought to be solely controlled by nerve signals.
- Emerging evidence highlights the role of extraocular muscles (EOMs) and their pulley system.
Purpose of the Study:
- To investigate the Active Pulley Hypothesis regarding EOMs and connective tissue pulleys.
- To explore the mechanical basis of ocular motor control, including Listing's law.
Main Methods:
- Review of functional imaging and histology studies.
- Analysis of human behavioral studies and primate neurophysiology.
- Characterization of pulley system pathology through imaging.
Main Results:
- The Active Pulley Hypothesis suggests EOMs actively control connective tissue pulleys.
- A gimbal-like mechanism in rectus pulleys, driven by obliques, may explain ocular motility.
- Mechanical, not central neural, implementation of Listing's law is supported.
Conclusions:
- The EOM pulley system offers a mechanical explanation for ocular motility and Listing's law.
- Pulley system pathologies correlate with treatable strabismus patterns.
- Mechanical determination suggests limitations for neural adaptation but potential for surgical intervention.
Related Concept Videos
01:16Circular Orbits and Critical Velocity for Satellites
The Moon orbits around the Earth. In turn, the Earth (and other planets) orbit the Sun. The space directly above our atmosphere is filled with artificial satellites in orbit. One can examine the circular orbit, the simplest kind of orbit, to understand the relationship between the speed and the period of planets and satellites with respect to their positions and the bodies that they orbit.
Nicolaus Copernicus (1473-1543) first suggested that the Earth and all other planets orbit the Sun in...
Nicolaus Copernicus (1473-1543) first suggested that the Earth and all other planets orbit the Sun in...
01:10Kepler's First Law of Planetary Motion
In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. He formulated his first two laws based on the observations of his forebears, Nikolaus Copernicus and Tycho Brahe.
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...
01:17Accessory Structures of the Eye
Optical perception, or vision, is an extraordinary sense dependent on converting light signals received via the ocular organs. These organs, known as eyes, are securely positioned within the bony cavities of the skull, called orbits. The orbits serve a dual purpose: a protective shield for the ocular globes and a stable attachment point for the soft ocular tissues. The eye's external protective mechanisms include the eyelids, which are edged with lashes that act as a barrier against foreign...
01:18Kepler's Third Law of Planetary Motion
In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. In 1909, he formulated his first two laws based on the observations of his forebears, Nikolaus Copernicus and Tycho Brahe. However, in 1918, he published his third law of planetary motion, which gives a precise mathematical relationship between a planet's average distance from the Sun and the amount of time it takes to revolve around the Sun. It...
01:15Torque Free Motion
The torque-free motion refers to the movement of a rigid body in space when no external torques are acting upon it. This type of motion can be observed in environments where there are no external forces or frictions, like in outer space. For example, a rotation of Mars in space is a torque-free motion. Mars is an axisymmetric object, meaning it has an axis of symmetry along which it rotates, designated as the z-axis. The rotating frame of reference is defined such that the center of mass of...
01:18Equation of Motion: Rotation About a Fixed Axis
Consider a flywheel, having an uneven mass distribution, rotating steadily around a fixed axis. As this rotation occurs, the center of mass of the flywheel traces a circular path. Understanding the acceleration of this center of mass requires observing both its tangential and normal components.
The tangential component is dependent on the direction of the angular acceleration of the flywheel. The tangential component of the acceleration propels the flywheel along its path. On the other hand,...
The tangential component is dependent on the direction of the angular acceleration of the flywheel. The tangential component of the acceleration propels the flywheel along its path. On the other hand,...