Ch.9 - JOINTS Flashcards
What is a joint?
point of contact between:
- Two or more bones
- Cartilage and bone
- Teeth and bone
Structural classifications of joints.
Anatomical criteria:
- presence or absence of a space between the articulating bones (joint cavity)
- type of CT
Functional classification of joints.
Functional criteria:
-degree of movement permitted
Structural classification subcategories:
fibrous joints, cartilaginous joints, and synovial joints.
Fibrous joints
bones held together by dense collagen fibers
cartilaginous joints
bones held together by cartilage
synovial joints
synovial cavity, bones held together by ligaments.
Freely moveable
Functional classification subcaterogies of joints
- synarthrosis
- amphiarthrosis
- diarthrosis
synarthrosis
immovable joint; immoveable joints, like the fibrous joints of the skull (sutures)
amphiathrosis
slightly movable joint; slightly movable joints like the cartilaginous pubic symphysis, intervetebral discs
diarthrosis
freely movable joint; freely moveable joints like the big “ball and socket” synovial joints of the shoulder and hip.
fibrous joints
lack cartilage and a synovial cavity.
- bones are held closely together by dense irregular CT
- little/no movement.
ex) suture joints in the skull and the teeth joints.
fibrous joints- suture
occur only between bones of the skull
fibrous joints- Syndesmosis
permit slight movement, such as the interosseous membrane between the tibia and fibula
Fibrous joints - gomphoses
occur between the teeth and the periodontal ligament
cartilaginous joints
They lack a synovial cavity and provide little or no movement.
Pubic symphysis, the intervertebral disks of the spine
synchondroses
type of cartilaginous joint.
made of hyaline cartilage, like the epiphyseal growth plates
symphyses
type of cartilaginous joint.
have hyaline cartilage sandwiching a disc of fibrocartilage; like the pubic symphysis and the intervertebral discs
synovial joint
Ligaments hold bones together to form a synovial cavity Nerve and blood supply -A two layered capsule encloses the synovial cavity: -An outer fibrous capsule -An inner synovial membrane
synovial fluid
Reduces friction by lubricating the joint Absorbs shock Supplies oxygen and nutrients to cartilage Removes carbon dioxide and metabolic wastes
synovial joints examples
Freely movable joints of the
arms, hips, and legs
Accessory structures of synovial joint
Joint capsule Ligaments Bursae Tendon sheaths Menisci
joint capsules
composed of dense irregular C.T., lined by a synovial membrane. They encompass the joint cavity and the synovial fluid within it.
ligaments (w/ ACL example)
bands of dense regular C.T. (like tendons) that join one bone to another bone. Ligaments can blend with other C.T. to become part of a joint capsule, or they can run inside or outside the joint.
example: The ACL (ligament) lies inside the knee joint, whereas the patellar ligament is outside the joint.
bursae
fluid-filled structures strategically placed to minimize friction in some joints.
tendon sheaths
tube-like bursae that
wrap around tendons
menisci
pads of dense fibrocartilage found between articular surfaces where hyaline cartilage predominates
These “articular discs” provide superior strength and allow bones of different shapes to fit together more tightly.
Nerve and blood supply of synovial joints: arterial branches
Arterial branches from several different arteries merge around a joint before penetrating the articular capsule.
Nerve and blood supply of synovial joints: nerve endings
Nerve endings respond to the degree of movement and stretch, and convey information about pain from the joint to the spinal cord and brain.
How man synovial joints? Details
There are 6 types of synovial joints based on the shapes of the articulating bone surfaces.
–Not all synovial joints have all (or any) accessory structures like ligaments and bursae – some of them are quite simple.
Planar joint
type of synovial joint.
In a planar joint, the articulating surface is flat or slightly curved, permitting back and forth and side-to-side
movements.
hinge joint
type of synovial joint.
In a hinge joint, the convex surface of one bone fits into the concave surface of another, producing an opening and closing action like a hinge.
pivot joint
type of synovial joint.
In a pivot joint, the rounded surface of one bone articulates with a ring structure formed by another bone and a ligament (allowing rotation around its longitudinal axis).
condyloid joint
Type of synovial joint.
In a condyloid joint, the convex oval-shaped projection of one bone fits into the oval-shaped depression of another bone (allowing movement around two axes).
Saddle joint
type of synovial joint.
In a saddle joint, the articular surface of one bone is saddle-shaped. This is really a modified condyloid joint, but the range of motion is expanded to include movement around all 3 axes.
ball-and socket joint
type of synovial joint.
In a ball-and-socket joint, the ball surface of one bone fits into a cup-like depression of another bone.
These joints allows the most movement of any joint.
The shoulder joint is a ball-and-socket synovial joint – it has the most range of motion of any joint in the body.
Range of motion defition
the range, measured in degrees of a circle, through which the bones of a joint can be moved.
what affects range of motion?
- Structure or shape of the articulating bones. The shape of the articulating bones determines how closely they fit together.
- The arrangement, strength and tension of the muscles and joint ligaments
- Contact of soft parts
- hormones
- disuse
how do hormones affect ROM?
Relaxin increases the flexibility of the pubic symphysis and loosens the ligaments between the sacrum and hip bone toward the end of pregnancy.
how does disuse affect ROM?
Movement may be restricted if a joint has not been used for an extended period.
Joint movement: gliding
relatively flat bone surfaces move back-and-forth and from side-to-side with respect to one another.
They are limited in range since there is no significant alteration of the angle between the bones.
Typical of the intercarpal joints
Joint movement: angular movement
there is an increase or a decrease in the angle between articulating bones.
Joint movement: rotation
a bone revolves around its own longitudinal axis.
Turning the head from side to side as when you shake your head “no”
Joint movement: special movement
- elevation
- depression
- protraction
- retraction
- inversion
- eversion
- dorsiflexion
- plantar flexion
Joint movement: angular movement - flexion
is a decrease in the angle.
Joint movement: angular movement - Extension
increase in the angle
Joint movement: angular movement - abduction
movement away from the midline.
Joint movement: angular movement - adduction
movement towards the midline.
circumduction
movement of a body part in a circle.
Joint movement: special movement- elevation
is an upward movement of a body part.
Closing the mouth
Joint movement: special movement- depression
is a downward movement of a body part.
Opening the mouth
Joint movement: special movement- protraction
is movement of a body part anteriorly, Thrusting the mandible outward
Joint movement: special movement- retraction
is movement back to normal.
Joint movement: special movement- inversion
movement of the foot medially.
Joint movement: special movement- eversion
moving the foot laterally.
Joint movement: special movement- dorsiflexion
bending of the foot at the ankle in an upward direction.
Joint movement: special movement- plantar flexion
bending the foot at the ankle in a downward direction.
Joint movement: special movement- supination
movement of the forearm so that the palm is turned upward.
Joint movement: special movement- pronation
movement of the forearm so that the palm is turned downward.
Joint movement: special movement- opposition
movement of our magnificent opposable thumb across the palm to touch the tips of the fingers on the same hand.
Important, representative joints of the body
- The temporomandibular joint
- The shoulder joint
- The elbow joint
- The hip joint
- The knee joint
Important, representative joints of the body- The temporomandibular joint
The temporomandibular joint is a combined hinge and planar joint formed by the mandible and the temporal bone - it is the only movable joint between the skull bones.
Important, representative joints of the body-The shoulder joint
The shoulder joint is a ball-and-socket joint formed by the head of the humerus and the scapula.
Important, representative joints of the body-The elbow joint
The elbow joint is a hinge joint formed by the humerus, the ulna, and the radius.
Important, representative joints of the body-The hip joint
The hip joint is a ball-and-socket joint formed by the femur and the os coxae.
Important, representative joints of the body-The knee joint
The knee joint is a modified hinge joint. It is the largest and most complex joint of the body.
By age 80, what happens to the body?
almost everyone develops some type of degeneration in the knees, elbows, hips, and shoulders.
Aging results in what?
- Thinning of articular cartilage
- Decreased production of synovial fluid in joints
- Loss of ligament strength and flexibility
Osteoarthritis
at least partially age-related.
Joint arthroplasty?
surgical implantation of an artificial joint to counter some effects of aging
-most commonly replaced: hips, knees, and shoulders
Partial hip replacement?
involve only the femur,
Total hip replacement?
involve both the acetabulum and head of the femur.
Potential complications of arthroplasty?
include infection, blood clots and nerve injury.
Components of artificial knee?
- femoral component
- tibial component with a plastic spacer
- patellar component
