Unit 4 Guide- Chapter 8 (Physio honors)- STUDY QUESTIONS

Define joint.

Physical point of connection between two bones

List three factors that stabilize a synovial joint.

1. Shapes of articular surface (minor role) 2. Ligament number and location (limited role) 3. Muscle tone which keep tendons that cross the joint taut.

Define cartilaginous joint. Describe and give an example of each of the two types of cartilaginous joints.

A cartilaginous joint is a joint where cartilage connects the bones. Cartilage is a tough but flexible connective tissue that comes in three types: hyaline (also called articular), elastic and fibrocartilage. Unlike the more common synovial joints, cartilaginous joints do not have a space (joint cavity) between the bones. The two types of cartilaginous joints are synchondroses and symphyses. Synchondrosis joint- In a synchondrosis joint, a bar or plate of hyaline cartilage connects the bones. During childhood, these joints provide a place for bone to grow, but most synchondroses become immovable (synarthrotic) after childhood. Example: the joint between first rib and the manubrium of the sternum, which also eventually turns into solid bone. Symphysis joint- In a symphysis joint, hyaline cartilage covers the articular surfaces of the bones. This cartilage fuses into a pad or plate of fibrocartilage. Because fibrocartilage is compressible and resilient, symphyses are slightly movable. Example: the intervertebral joints (between the bones of the spine) and the pubic symphysis of the pelvis.

Define fibrous joint. Describe and give an example of each of the three types of fibrous joints.

Fibrous joint- a union of two bones by fibrous tissue such that there is no joint cavity and almost no motion possible; the types of fibrous joints are sutures, syndesmoses, and gomphoses. Sutures- a seam-like immovable junction between two bones, such as those of the skull. Syndesmoses- an immovable joint in which bones are joined by connective tissue (e.g., between the fibula and tibia at the ankle). Gomphoses- an immovable articulation in which one bone or part is received in a cavity in another, as a tooth in its socket.

Compare the four ranges of motion allowed by synovial joints (axial movements).

Gliding movements- occur as relatively flat bone surfaces move past each other, but they produce very little movement of the bones. Angular movements- produced when the angle between the bones of a joint changes; they include flexion, extension, hyperextension, abduction, adduction, and circumduction. Rotational movement- involves moving the bone around its longitudinal axis; this can be movement toward the midline of the body (medial rotation) or away from the midline of the body (lateral rotation). Special movements- all the other movements that cannot be classified as gliding, angular, or rotational; these movements include inversion, eversion, protraction, and retraction.

Contrast the origin and insertion of a muscle.

Origin - attachment to the immovable bone Insertion - attachment to the movable bone **Movements occur along transverse, frontal, or sagittal plane.

Define synovial joint. List the five distinguishing features of a synovial joint.

Synovial joint- the most common and movable type of joint which is characterized by the presence of a layer of fibrocartilage or hyaline cartilage that lines the opposing bony surfaces, as well as a lubricating synovial fluid within the synovial cavity. The five distinguishing features of the synovial joints are: Synovial Joints Distinguishing Features : - All are diathrotic - Include all limb joints, most joints of the body 1. Articular cartilage : hyaline cartilage 2. Joint synovial cavity ; small potential space 3. Articular joint capsule : - outer fibrous capsule of dense irregular connective tissue - inner synovial membrane of loose connective tissue 4. Synovial Fluid -viscous slippery filtrate of plasma and hyaluronic acid -lubricates and nourishes articular cartilage 5. Three possible types of reinforcing ligaments - capsular (intrinsic) - part of the fibrous capsule - extracapsular - outside the capsule - intrascapular - deep to capsule covered by the synovial membrane 6. Rich nerve and blood vessel supply - nerve fibers detect pain, monitor, joint position, and stretch - capillary beads produce filtrate for synovial fluid

Compare the three types of functional classifications for joints.

The three types of functional classification for joints are fibrous joint, cartilaginous joint, and synovial joint. Fibrous joint- have no joint cavity and are connected via fibrous connective tissue. The skull bones are connected by fibrous joints. Sutures are found between bones of the skull. Cartilaginous joint- connected entirely by cartilage (fibrocartilage or hyaline). Cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint. Synovial joint- the most common and most movable type of joint in the body of a mammal. As with most other joints, synovial joints achieve movement at the point of contact of the articulating bones.