Sports Medicine: Anatomy Lessons to Remember

At our orthopedic corner we like to talk about all the topics that can help you prevent yourself from an orthopedic injury as well as guide you in the right direction when you have or suffer one. We also have been introducing some lifestyle tips to help you improve your quality of life as you progress in age. As part of our strong commitment to always give you valuable information, today we decided to give you some anatomy lessons of specific topics we always talk about. So, lets go further with:

Joints

A joint, or articulation, is formed when two bones connect. There are two major classifications of joints: synarthodial (a joint with no separation or articular cavity, such as the skull) and diarthrodial (a freely movable joint with an articular cavity).

A diarthodial (freely movable) joint has an articular cavity encased in a ligamentous capsule. Synovial fluid lubricates the smooth cartilage inside the capsule. Synovial fluid lubricates the smooth cartilage inside the capsule. Diarthodial joints are classified in six categories: arthroidial (gliding) joint, condyloidal (biaxial ball-and-socket) joint, enarthrodial (multi axial ball-and-socket) joint, giglymus (uniaxial hinge) joint, sellar (saddle) joint and trochoidal (pivot) joint.

• Arthrodial joints permit limited gliding movement and include bones of the wrist and the tarsometatarsal joints of the foot. The are characterized by two flat, bony surfaces that press up against each other.
• Ginglymus joints permit a wide range of movement in one plane. Examples of hinge joints are the elbow, ankle and knee joint.
• Condyloidal joints permit movement in two planes without rotation and include the wrist between the radius and the proximal row of carpal bones and the second, third, fourth and fifth metacarpophalangeal joints.
• Enarthrodial (multi axial ball-and-socket) joints permit movement in all planes and include the shoulder and hip joints.
• Sellar (saddle) joints permits ball and socket movement with the exception of rotation. The thumb is the only saddle joint in the body and is capable of reciprocal reception.
• Trochoidal (pivot) joints permit rotational movement around a long axis as with the rotation of the radius at the radioulnar joint.

Connective Tissue

The primary function of dense connective tissue is to connect muscle to bone and to connect joints together. Comprised of fiber called collagen, mature tissue has fewer cells than others tissues and therefore, needs (and receives) less blood and the oxygen and other nutrients found in it.

Each collagen bundle is comprised of several fibers, which, in turn, contain several fibrils. These fibrils contain the actual collagen molecules, which are triple helix in structure.

Tendons

Tendons are extensions of the muscle fibers that connect muscle to bone. They are slightly more elastic than ligaments, but cannot shorten as muscles do.

Various proprioceptors, the sensory organs found in muscles and tendons, provide information about body movement and position, and protect muscle and connective tissue. The Golgi tendon organ is imbedded in tendon tissue and can be thought of as safety valve. Increasing levels of muscular contraction result in feedback to the nervous system from the Golgi tendon organ. When tension becomes great (greater than your brain can recall) this signal inhibits the contraction stimulus, therefore reducing the likelihood of injury. This protective response is called “the feedback loop.”

Ligaments

Ligaments connect bones to bones at a joint and along with collagen, contain a somewhat elastic fiber called elastin. With ligaments must have some elasticity to allow for joint movement, it is a limited amount.

Cartilage

Cartilage is a firm, elastic, flexible, white material. It is found at the ends of ribs, between vertebrae (discs), at joint surfaces, and in the nose and ears. As a smooth surface between adjacent bones, cartilage provides both shock absorption and structure. Cartilage also lubricates the working parts of a joint. Unlike tendons and ligament, cartilage has no blood supply of its own. The only way for cartilage to receive oxygen and nutrients is through diffusion. Because of this lack of nutrients, damaged cartilage heals very slowly.

Orthopedic Corner | Leon Mead MD Orthopedic Doctor | 730 Goodlette Road North, Suite 201  Naples Florida 34102 | Phone: (239) 262-1119