Download JOINTS AND RELATED STRUCTURES

JOINTS AND RELATED
STRUCTURES
• Articulations – points of contact b/w 2
bones.
• Classified based on degree of movement
Classification of joints:
• Diarthroses
– Freely movable joints (synovial joints)
• Amphiarthroses
– Joints that allow some motion (symphysis
pubis)
• Synarthroses
– Immovable joints (skull sutures)
Structural classification of joints
• Fibrous
– Consist of bones joined by short connective
tissue fibers, most are synarthroses.
• Cartilaginous
– Consist of bones united by cartilage rather
than fibrous connective tissue, most are
amphiarthrotic
• Synovial
– Consist of a true joint cavity and consist of 2
bones whose articular ends are covered
w/hyaline cartilage.
Synovial joints
• Structure
– Joint cavity is lined by a synovial membrane,
which secretes a watery fluid similar in
composition to blood plasma w/o proteins.
– Joint capsule is made of dense irregular CT
and serves to provide strength and struc.
reinforcement for the joint.
– Synovial memb. lines the joint capsule.
– Articular cartilage, hyaline cartilage. Provides
a smooth, frictionless surface on which the
bones slide.
Synovial joints
• Structure (Cont’d)
– Ligaments connect bones to bones, to
strengthen the joint. Some are w/I the joint
cavity - extrinsic ligaments. Some are
embedded in the capsule – intrinsic
ligaments.
– Articular discs – aka menisci, fibrocartilage
pads improve the fit of two bones to prevent
disolcation.
Synovial joints
• Surrounded by:
– Tendon sheath, a sheath of connective tissue
that surrounds the tendon, in which it can
slide with a minimum of friction.
– Bursa, a fluid-filled sac between the tendon
and the joint, to lesson friction.
TYPES OF MOTION
• Flexion
– Bringing 2 bones closer together, decreasing
the angle b/w them
• Extension
– Act of increasing the angle b/w 2 bones,
straightening motion
• Abduction
– Movement of extremity away from the body.
Hyperextension
increases the joint angle beyond the anatomic
position.
TYPES OF MOTION
• Adduction
– Movement of extremity toward the body
• Circumduction
– Includes, flexion, extension, abduction, adduction
• Rotation
– Bone moves around a central axis
• Pronation – palm is downward/backward
• Supination – palm is forward/upward.
TYPES OF MOTION
• Eversion
– Moving foot away from the midline.
• Inversion
– Moving the foot toward the midline
• Retraction
– Moving the body backward on a plane parallel to the
ground
• Protraction
– Moving the body forward on a plane parallel to the
ground.
TYPES OF MOTION
• Elevation
– Raising a part of the body
• Depression
– Lowering a part of the body
• Oppostion
– Tip of thumb and fingers are brought together
• Reposition
– When the digits to turn their normal positions
• Dorsiflexion
– Raising the foot up at the ankle joint
• Plantar flexion
– Pushing the foot down at the ankle.
Types of joints:
• Ball and socket
– Multiaxial joint, ball-shaped head fits into a concave
socket.
– Exs. femur and acetabulum, humerus and scapula
– Widest range of motion, all planes and directions.
• Hinge joint
–
–
–
–
Convex surface fits into a concave surface.
Limited to flexion and extension.
Uniaxial joints
Exs. Knee, elbow, middle and distal phalanges
Types of joints
• Pivot joint
– Uniaxial joint
– Motion is limited to a single plane.
– Pivot process rotates w/I a “hole” around a
longitudinal axis.
– Exs. Atlas and axis
• Condyloid joint
–
–
–
–
Biaxial joint
Oval shaped protrusion that fits into an elliptical cavity
Motion in at right planes of each other.
Ex. Wrist, ankle
Types of joints
• Saddle joint
– Biaxial joint
– Movement is possible in two planes at right angles to
each other, flexion and extension plus abduction and
adduction.
– Ex. Joint at phalangial and metacarpal/metatarsal end
• Gliding joint
– Multiaxial joint
– Gliding motions
– Ex. Superior and inferior articular processes of the
vertebrae of the spine.
Injury of bones and joints
• Fracture
– Restoring bone:
• Closed reduction – manipulation , cast or splint.
• Open reduction – surgical interventions, wires, metal plates,
or screws.
• Traction – pulling force, holds bones in place, long bones.
– Types:
•
•
•
•
Greenstick- simplest, partly bent, never separates
Closed/simple –bone broken, not pierce t/skin.
Open/compound-broken bones pierces t/skin
Comminuted – bone is splintered
Injury of bones and joints
• Dislocation
– When a bone is displaced from its proper position in a
joint.
– May result in tearing or stretching of the ligaments.
– Reduction is necessary along w/rest to allow the
ligaments to heal.
• Sprain
– Caused by a sudden or unusual motion.
– Ligaments are usually torn
– Treated w/ nonsteroidal anti-inflammatory drugs
(NSAIDs).
DISORDERS OF THE
BONES AND JOINTS
Making connections
• Integumentary
– S support for organs.
– I provides vitamin D needed for Ca++
absorption and use
• Muscular
– S provided levers and Ca++ for muscle
activity.
– M pulls on bones, h bone strength and
viability.
Making connections
• Nervous
– S protects brain & spinal cord, depot for Ca++ ions.
– N innervate bone and joint capsules for pain and joint
sense.
• Endocrine
– S– protection, Ca++ stores.
– E – hormones regulate uptake and release of Ca++,
promote long bone growth and maturation.
Making connections
• Cardiovascular
– S bone marrow site of blood cell formation, Ca++
stores for cardiac muscle activity.
– C – delivers nutrients and O2 to bones, carries away
wastes.
• Lymphatic
– S protection of lymphatic organs, bone marrow site of
lymphocyte production.
– L drains leaked tissue fluids, immune cells protect
against pathogens.
Making connections
• Respiratory
– S protects lungs
– R provides O2, disposes of CO2
• Digestive
– S protection of intestines, pelvic organs, and
liver
– D provides nutrients needed for bone health
and growth
Making connections
• Urinary
– S protects pelvic organs
– U activates vitamin D, disposes of
nitrogenous wastes.
• Reproductive
– S protects reproductive glands
– R gonads produce hormones that influence
form of skeleton and epiphyseal closure.