The Skeletal System - Joints
The Skeletal System - Joints
The Skeletal System - Joints
THE JOINTS
THE FOLLOWING TOPICS WILL BE
DISCUSSED IN THIS UNIT:
Joint Classifications
Fibrous Joints
Cartilaginous Joints
Synovial Joints
Types of Movements at Synovial Joints
Types of Synovial Joints
Factors Affecting Contact and Range of Motion at
Synovial Joints
Selected Joints of the Body
Aging and Joints
Arthroplasty
JOINTS (JOINT CLASSIFICATION)
The structural classification of joints
Fibrous joints (bones held together by dense
collagen fibers)
Cartilaginous joints (bones held together by
cartilage)
Synovial joints (bones held together by
ligaments)
The functional classification of joints
Synarthrosis (an immovable joint)
Amphiarthrosis (a slightly movable joint)
Diarthrosis (a freely movable joint)
JOINTS (FIBROUS JOINTS)
Lack a synovial cavity
The articulating bones are held very closely together
by dense irregular connective tissue
Fibrous joints permit little or no movement
Three types of fibrous joints
Sutures
Syndesmoses
Gomphoses
JOINTS (FIBROUS JOINTS)
Sutures
Occur only between bones of the
skull
Syndesmoses
Permits slight movement
Interosseous membrane
Between the tibia and fibula in the leg
Gomphoses
Immovable joint
Joint in which a cone-shaped peg
fits into a socket
Articulations of the teeth with the
sockets of the maxillae and
mandible
JOINTS (CARTILAGINOUS JOINTS)
Lacks a synovial cavity
Allows little or no movement
Symphyses
Slightly movable joint
Ends of the articulating bones are covered with hyaline
cartilage, but a disc of fibrocartilage connects the bones
Pubic symphysis
Between the anterior surfaces of the hip bones
Intervertebral joints between the vertebrae
JOINTS (SYNOVIAL JOINTS)
Synovial cavity allows a joint to be freely movable
Ligaments hold bones together in a synovial joint
Articular Capsule
A sleeve-like capsule encloses the synovial cavity
The articular capsule is composed of two layers
an outer fibrous capsule
an inner synovial membrane
Synovial Fluid
The synovial membrane secretes synovial fluid
Functions to reduce friction by:
lubricating the joint
absorbing shocks
Menisci
Pads of cartilage lie between the articular surfaces of the bones
Allow bones of different shapes to fit together more tightly
JOINTS (SYNOVIAL JOINTS)
Nerve and Blood Supply
Nerve endings convey information about pain from the joint
to the spinal cord and brain
Tendon sheaths
Wrap around tendons
Reduce friction at joints
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
Specific terminology is used to designate the movements that
occur at joints
Movements are grouped into four main categories:
1) Gliding
2) Angular movements
3) Rotation
4) Special movements
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
Gliding
Simple movement back-and-forth and from side-to-side
There is no significant alteration of the angle between the bones
Limited in range
Intercarpal joints
Angular Movements
Increase or a decrease in the angle between articulating bones
Angular movements include
Flexion
Extension
Lateral flexion
Hyperextension
Abduction
Adduction
Circumduction
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
Flexion
Decrease in the angle between articulating bones
Bending the trunk forward
Extension
Increase in the angle between articulating bones
Flexion and extension are opposite movements
Lateral flexion
Movement of the trunk sideways to the right or left at the waist
Hyperextension
Continuation of extension beyond the normal extension
Bending the trunk backward
Abduction
Movement of a bone away from the midline
Moving the humerus laterally at the shoulder joint
Adduction
Movement of a bone toward the midline
Movement that returns body parts to normal position from abduction
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
Circumduction
Movement of a body part in a circle
Moving the humerus in a circle at the shoulder joint
Rotation
A bone revolves around its own longitudinal axis
Turning the head from side to side as when you shake your head “no”
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
Special Movements
Elevation
Depression
Protraction
Retraction
Inversion
Eversion
Dorsiflexion
Plantar flexion
Supination
Pronation
Opposition
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
Elevation
Upward movement of a part of the body
Closing the mouth
Its opposing movement is depression
Depression
Downward movement of a part of the body
Opening the mouth
Protraction
Movement of a part of the body anteriorly
Thrusting the mandible outward
Its opposing movement is retraction
Retraction
Movement of a protracted part of the body back to normal
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
Inversion
Movement of the foot medially
Its opposing movement is eversion
Eversion
Movement of the sole laterally
Dorsiflexion
Bending of the foot at the ankle in an upward direction
Its opposing movement is plantar flexion
Plantar flexion
Bending of the foot at the ankle in a downward direction
Supination
Movement of the forearm so that the palm is turned upward
Its opposing movement is pronation
Pronation
Movement of the forearm so that the palm is turned downward
Opposition
Movement of the thumb in which the thumb moves across the palm to touch the
tips of the fingers on the same hand
JOINTS (TYPES OF MOVEMENTS AT
SYNOVIAL JOINTS)
JOINTS (TYPES OF SYNOVIAL JOINTS)
Synovial
joints are classified based on type of
movement
Planar
Hinge
Pivot
Condyloid
Saddle
Ball-and-socket
JOINTS (TYPES OF SYNOVIAL JOINTS)
Planar Joints
Primarily permit back-and-forth and side-to-side movements
Intercarpal joints
Hinge Joints
Produce an opening and closing motion like that of a hinged door
Permit only flexion and extension
Knee and elbow
JOINTS (TYPES OF SYNOVIAL JOINTS)
Pivot Joints
Surface of one bone articulates with a ring formed partly by another bone
Joints that enable the palms to turn anteriorly and posteriorly
Condyloid Joints
The projection of one bone fits into the oval-shaped depression of another bone
Wrist
JOINTS (TYPES OF SYNOVIAL JOINTS)
Saddle Joints
Articular surface of one bone is saddle-shaped, and the articular surface of the
other bone fits into the “saddle”
Thumb
Ball-and-Socket Joints
Ball-like surface of one bone fitting into a cuplike depression of another bone
Shoulder and hip
JOINTS (TYPES OF SYNOVIAL JOINTS)
JOINTS (FACTORS AFFECTING CONTACT AND
RANGE FOR MOTION AT SYNOVIAL JOINTS)
Hormones
Flexibility may also be affected by hormones
Relaxin increases the flexibility of the pubic symphysis and loosens
the ligaments between the sacrum and hip bone toward the end of
pregnancy
Disuse
Movement may be restricted if a joint has not been used for an
extended period
JOINTS (SELECTED JOINTS OF THE BODY)
The selected joints described are:
Temporomandibular joint
Shoulder joint
Elbow joint
Hip joint
Knee joint
JOINTS (SELECTED JOINTS OF THE BODY)
Temporomandibular Joint
Combined hinge and planar joint formed by the mandible
and the temporal bone
Only movable joint between skull bones
Only the mandible moves
JOINTS (SELECTED JOINTS OF THE BODY)
Shoulder Joint
Ball-and-socket joint formed by the head of the humerus
and the scapula
More freedom of movement than any other joint of the body
JOINTS (SELECTED JOINTS OF THE BODY)
Elbow Joint
Hinge joint formed by the humerus, the ulna, and the radius
JOINTS (SELECTED JOINTS OF THE BODY)
Hip Joint
Ball-and-socket joint formed by the femur and the hip bone
JOINTS (SELECTED JOINTS OF THE BODY)
Knee Joint
Largest and most complex joint of the body
Modified hinge joint
JOINTS (SELECTED JOINTS OF THE BODY)
Knee Joint
JOINTS (SELECTED JOINTS OF THE BODY)
JOINTS (SELECTED JOINTS OF THE BODY)
JOINTS (AGING AND JOINTS)
Aging
May result in decreased production of synovial fluid
The articular cartilage becomes thinner
Ligaments shorten and lose some of their flexibility
Osteoarthritis is partially age-related
Stretching and aerobic exercises are helpful in minimizing
the effects of aging
Help to maintain the effective functioning of ligaments,
tendons, muscles, synovial fluid, and articular cartilage
JOINTS (ARTHROPLASTY)
• Arthroplasty
– Joints may be replaced surgically with artificial joints
– Most commonly replaced are the hips, knees, and shoulders
• Hip Replacements
– Partial hip replacements involve only the femur
– Total hip replacements involve both the acetabulum and
head of the femur
• Knee Replacements
– Actually a resurfacing of cartilage and may be partial or
total
– Potential complications of arthroplasty include infection,
blood clots, loosening or dislocation of the replacement
components, and nerve injury
JOINTS (ARTHROPLASTY)
JOINTS (ARTHROPLASTY)
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