Which joint is the largest and most complex joint in the body?

The knee joint (tibiofemoral joint) is the most complex in the human body. It is comprised of three different joints: the medial femoral and medial tibial condyles, the lateral femoral and tibial condyles, and the articulation between the patella and the femur. The knee joint is capable of flexion, extension, and medial and lateral rotation to a certain degree. It is also the joint most vulnerable and susceptible to injury. Common knee injuries are tears to the anterior cruciate ligaments (ACL) and tears to the meniscus or cartilage.

What does it mean when someone is “double-jointed”?

Being “double-jointed” (more accurately called joint hypermobility) does not mean having extra joints, but rather having unusually flexible joints, especially of the limbs or fingers. Double-jointed individuals have loose articular capsules.

What does it mean when someone is “double-jointed”?

Being “double-jointed” (more accurately called joint hypermobility) does not mean having extra joints, but rather having unusually flexible joints, especially of the limbs or fingers. Double-jointed individuals have loose articular capsules.

What are the four categories of possible movements by synovial joints?

The four basic categories of movements are gliding, angular movements, rotation, and special movements. Each of these groups is defined by the form of motion, the direction of movement, or the relationship of one body part to another during movement. Gliding movements are generally simple back-and-forth or side-to-side movements. Angular movements include flexion, extension, abduction, adduction, and circumduction. In each of these movements there is an increase or decrease in the angle between articulating bones. In rotational movements a bone revolves around its own longitudinal axis. Special movements occur only at certain joints. These movements include elevation, depression, protraction, retraction inversion, eversion, dorsiflexion, plantar flexion, supination, and pronation.

Which type of joint is most easily dislocated?

The ball-and-socket joint is most susceptible to dislocation. Joint dislocation, or luxation (from the Latin luxare, meaning “to put out of joint”), occurs when the there is a drastic movement of two bone ends out of their normal end-to-end position. The most frequently dislocated joint is the shoulder joint. Since the socket is shallow and the joint is loose, allowing for the tremendous amount of mobility, there is also the greatest possibility of dislocation.

Why is there a “popping” sound when you crack your knuckles, and is it dangerous to crack them?

A number of reasons have been given for the characteristic “popping” sound associated with someone cracking their knuckles. One reason is that when a joint is contracted, small ligaments or muscles may pull tight and snap across the bony protuberances of the joint. Another possibility is that when the joint is pulled apart, air can pop out from between the bones, creating a vacuum that produces a popping sound. A third reason, discovered by British scientists in 1971, is that when the pressure of the synovial fluid is reduced by the slow articulation of a joint tiny gas bubbles in the fluid may burst, producing the popping sound. Research has not shown any connection between knuckle cracking and arthritis. One study found that knuckle cracking may be the cause of soft tissue damage to the joint capsule and a decrease in grip strength. The rapid, repeated stretching of the ligaments surrounding the joint is most likely the cause of damage to the soft tissue. Some researchers believe that since the bones of the hand are not fully ossified until approximately age 18, children and teenager who crack their knuckles may deform and enlarge the knuckle bones. However, most researchers believe knuckle cracking does not cause serious joint damage.