Types of Joints and Muscles

Science PowerPointby Group 4

JOINTS

A joint, or articulation, is the place where two bones come together. There are three types of joints classified by the amount of movement they allow: immovable, slightly movable, and freely movable.

Joints are mainly classified structurally and functionally.

Ball-and-SocketThe ball-shaped end of one bone fits into a cup shaped socket on the other bone allowing the widest range of motion including rotation. Examples include the shoulder and hip.

CondyloidOval shaped condyle fits into elliptical cavity of another allowing angular motion but not rotation. This occurs between the metacarpals (bones in the palm of the hand) and phalanges (fingers) and between the metatarsals (foot bones excluding heel) and phalanges (toes).

SaddleThis type of joint occurs when the touching surfaces of two bones have both concave and convex regions with the shapes of the two bones complementing one other and allowing a wide range of movement. The only saddle joint in the body is in the thumb.

PivotRounded or conical surfaces of one bone fit into a ring of one or tendon allowing rotation. An example is the joint between the axis and atlas in the neck.

HingeA convex projection on one bone fits into a concave depression in another permitting only flexion and extension as in the elbow and knee joints.

Gliding

 Flat or slightly flat surfaces move against each other allowing sliding or twisting without any circular movement. This happens in the carpals in the wrist and the tarsals in the ankle. 

MUSCLES

Muscle tissues consists of fibers (cells) that are highly specialized for the active generation of force for contraction. Because of this characteristic, muscle tissue provides motion, maintenance of posture, and heat production. Based on certain structural and functional characteristics, muscle tissue is classified into three types: cardiac, smooth and skeletal.

Cardiac

Cardiac muscle tissue forms the bulk of the wall of the heart. Like skeletal muscle tissue, it is striated (the muscle fibers contain alternating light and dark bands (striations) that are perpendicular to the long axes of the fibers). Unlike skeletal muscle tissue, its contraction is usually not under conscious control (involuntary).

SmoothSmooth muscle tissue is located in the walls of hollow internal structures such as blood vessels, the stomach, intestines, and urinary bladder. Smooth muscle fibers are usually involuntary (not under conscious control), and they are nonstriated (smooth). Smooth muscle tissue, like skeletal and cardiac muscle tissue, can undergo hypertrophy. In addition, certain smooth muscle fibres, such as those in the uterus, retain their capacity for division and can grow by hyperplasia.

SkeletalSkeletal muscle tissue is named for its location - attached to bones. It is striated; that is, the fibers (cells) contain alternating light and dark bands (striations) that are perpendicular to the long axes of the fibers. Skeletal muscle tissue can be made to contract or relax by conscious control (voluntary).