A&P chapter 8

The Focus Figure of Synovial Joints has examined a number of types of movement and the joints in which they are located. Review the types you have studied, and select a true statement or characteristic of uniaxial movement in a representative joint.

A person curls his or her fingers, and the phalanges flex at the interphalangeal joints. Uniaxial hinge-type joints include those that are interphalangeal (between the fingers or toes), as well as that of the elbow. These exhibit flexion and extension. Another uniaxial joint is a cylindrical bone rotating along one axis in a sleeve-type opening, the pivot joint, as in atlas-axis (also known as atlantoaxial) rotation or the proximal radioulnar joints. Biaxial joints include the condylar joint, as found in the metacarpophalangeal joint, and the saddle joint, as found in the carpometacarpal joints of the thumbs. Congratulations on expanding your knowledge of joint classification by recognizing both movements permitted and the shapes of the articulating bones!

What element of fibrous joints gives the joint its ability to resist stretching and control the amount of movement at the joint?

Collagen fibers

Focus your attention on the section called Nonaxial movement in part (a) in Focus Figure 8.1. Sort the descriptive phrases, which describe either nonaxial movement or some other type of movement, into the appropriate bins.

Explanation- non axial joints are those which don't operate around any axis. These include gliding movement, which means sliding of one bone over the other. Explanation- these two movement occur around specific axis. Flexion at elbow joint is a type of hinge joint which occur around one horizontal axis.

Focus your attention on the section called Multiaxial movement in part (f) in Focus Figure 8.1.Which of the following represents a correct statement about multiaxial joints?

Movement in more than two axes is permitted in a multiaxial joint. The multiaxial joint has movement in three directions, around all three axes in space, permitting the most movement of any joint type.

Which of the following joint problems is the result of an autoimmune problem?

Rheumatoid arthritis (RA) In RA, the body's immune system attempts to destroy the tissues in the joints in an apparent case of "mistaken identity."

Dislocation of a joint is a common orthopedic problem. Which of these joints is MOST likely to be dislocated?

Shoulder (glenohumeral) The articulation between the head of the humerus and the glenoid cavity allows for maximum flexibility but sacrifices stability.

Babies are often born with a slightly misshapen head that corrects itself over time. However, in some children suffering from craniosynostosis, the sutures fuse too early and either surgical intervention or corrective helmets must be worn to help correct the problem. Which set of sutures would most likely be affected if the child's head was too short in the anterior-posterior dimension and too tall in the forehead region?

The coronal sutures These large sutures separating the frontal and parietal bones allow for normal anterior-posterior growth of the infant's skull. Return to Assignment

A joint held together by fibrocartilage would be classified as a __________ joint.

cartilaginous Cartilaginous joints are held together by cartilage. Fibrocartilage holds together symphyses.

Which factor is likely to most likely to protect against shoulder dislocation?

rotator cuff muscles Tendons of the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) surround and provide stability to the shoulder joint.

Which joint has most notably sacrificed stability to provide great freedom of movement?

shoulder In the shoulder joint, stability has been sacrificed to provide the most freely moving joint in the body. The articulating bones provide minimal joint stability because of the size and "fit" of the articulating surfaces. The major stabilizing forces are soft tissue, in particular the tendons of the rotator cuff muscles (via muscle tone).

What factor does not contribute to the strength and stability of a synovial joint?

synovial fluid