Lesson 2: Joint Structure and Function Flashcards
Joints
A joint is a place where two or more bones meet.
Joints along with muscles enable movement and support of the body.
Most joints involve the bones, muscles, tendons, ligaments and nerves.
Bones provide support and act as levers allowing the force generated in the muscles to cause movement
Ligaments attach bone to bone at a joint
Tendons attach muscle to bone
Muscles provide force. Muscles only cause movement by contraction.
Motor neurons stimulate muscle contraction
Synovial Joints
A synovial joint is surrounded by a protective capsule formed by ligaments.
This capsule is lined by a membrane that secretes synovial fluid for reduced friction during movement.
Cartilage covers the ends of the bone at the joint to reduce friction and absorb pressure as the joint moves.
The Elbow Joint
The elbow joint is a synovial hinge
joint. It is named due to the fact
that its motion resembles that of a
door hinge. The knee is also a hinge
joint.
The elbow joint is formed by three
bones; the humerus in the upper
arm and the radius and ulna in the
lower.
The biceps and triceps are
attached to these bones.
This type of joint only allows
motion in one plane.The elbow joint, actually consists
of two different joint types.
The main joint is the hinge joint
formed by the humerus and the
ulna. However the ability to
rotate the lower arm at the
elbow is made possible by the
pivot joint between the ulna and
the radius.
This allows the radius to rotate
within a notch in the ulna.
The Hip Joint
The hip joint is a synovial
ball-and-socket joint.
This type of joint contains a ball
shaped head of one bone (in this
case, the femur) that fits into a
socket in the other (in this case, the
hip).
Ball-and-socket joints allow for
movement in more than one
direction and also allow for
rotational movement.
The shoulder is also a
ball-and-socket joint.
The Hands
A series of hinge and pivot joint
in the wrist (carpals) and fingers
(metacarpals and phalanges)
allow the fine manipulations that
human hands are capable of.
A saddle joint that connects the
thumb to the carpal in the wrist,
provides the unique movements
of the human thumb.
