A&P Chapter 8 Flashcards
Classes of Joints
Fibrous joints - Sutures - syndesmoses - gomphosis Cartilaginous joints - Synchondroses - Symphyses Synovial joints
Fibrous Joints
Sutures - Seams between skull bones Syndesmoses - Fibrous joint joined by ligament Gomphoses - Pegs that fit into sockets
Suture
Opposing bones interdigitate.
Sutural ligament:
- two periostea plus dense, fibrous, connective tissue between.
Fontanels:
- membranous areas in the suture between bones. Allow change in shape of head during birth and rapid growth of the brain after birth.
Syndesmoses
- Bones farther apart than suture and joined by ligaments
- Some movement may occur
- Examples: radioulnar (interosseus membrane)
Gomphoses
Specialized joints
Pegs that fit into sockets
Held in place by regular collagenous tissue
Only found in teeth and mandible/maxilla
Peridontal bundle
- Connective tissue between teeth & sockets
Cartilaginous Joints
United 2 bones by either hyaline or fibrocartilage Synchondroses - Joints containing hyaline cartilage Symphyses - Joints containing fibrocartilage
Synchondroses
2 bones joined by hyaline cartilage Little or no movement Examples - Epiphyseal plates of growing bones - 1st rib and the sternum
Symphyes
Fibro-cartilage uniting 2 bones Movable Examples - Manubrium and body of sternum - Symphysis pubis - -Inter-vertebral disks
Synovial Joints
Contain synovial fluid Allow considerable movement Articular cartilage covers articulation sites Articular disk - Lies between articular cartilages Meniscus - Articular disk in knee or wrist
General Structural Features
Joint cavity - Encloses articular surfaces of 2 bones Joint Capsule - Encases joint cavity - Contains synovial membrane Synovial membrane - Produces synovial fluid rich in hyaluronic acid
Bursa
Synovial membrane extends to form a sac Contains synovial fluid Provides cushioning to prevent rubbing Bursitis - Inflammation of bursa & restricts movement
Types of Synovial Joints
Classified by shape of articular surfaces: Plane (Gliding) Saddle Hinge Pivot Ball-and-socket Ellipsoid
Movement of Synovial Joints
Uniaxial - One axis Biaxial - Two axes Multiaxial - Several axes
Plane Joint
2 flat bones of equal size that can glide
Movement is uniaxial
Example:
- Intervertebral
- intercarpal
- Carpometacarpal
- costovertebral, intertarsal, sacroiliac, tarsometatarsal
Saddle Joint
2 saddle shaped articulating surfaces oriented at right angles Biaxial joints Example - Carpometacarpal joint of the thumb
Hinge Joint
Uniaxial movement Convex portion of one bone articulates with concave portion of another bone Examples - Elbow - Knee - Ankle
Knee Joint
Meniscus: fibrocartilage articular disks that build up the margins of the tibia and deepen articular surface
Cruciate ligaments: extend between tibia and femur
- Anterior cruciate ligament (ACL). Prevents anterior displacement of tibia
- Posterior cruciate ligament (PCL). Prevents posterior displacement of tibia
Ankle (talocural) Joint
Highly modified hinge joint Lateral and medial thickening of articular capsule to prevent side-to-side movement Ligaments of arch - Hold bones in proper relationship - Transfer weight
Pivot Joint
Uniaxial movement Restricted movement around a single axis Cylindrical bony process that rotated within a ring of bone & ligaments Examples - Radius and ulna - Dens and atlas
Ball and Socket
A ball (head) one one bone fits into socket of another Multiaxial movement Examples - Shoulder - Hip
Hip (coxal) Joint
- Ball-and-socket with acetabulum deepened by fibrocartilage acetabular labrum and transverse acetabular ligament
- More stable but less mobile than shoulder joint
Ellipsoid Joint
- Modified ball-and-socket joint
- Ellipsoid articular surface rather than ball
- Biaxial movement
- Hinge motion in 2 axes
- Restricted rotation
Example
- Atlantooccipital joint of neck
Temporomandibular Joint (TMJ)
- Combination plane and ellipsoid joint
- Fibrocartilage disk divides joint into superior and inferior cavities
Types of Movement
Gliding: in plane joints; slight movement Angular - Flexion and Extension * Hyperextension * Plantar and Dorsiflexion - Abduction and Adduction Circular - Rotation - Pronation and Supination - Circumduction
Flexion and Extension
Flexion: movement of a body part anterior to the coronal plane
Extension: movement of a body part posterior to the coronal plane
Hyperextension
- Abnormal forced extension beyond normal range of motion
- Can lead to breaks and/or dislocations
- Commonly used as submission method in Judo and Jui-jitsu
Dorsiflexion and Plantar Flexion
Plantar flexion: standing on the toes
Dorsiflexion: foot lifted toward the shin
Abduction and Adduction
Abduction: movement away from the median plane
Adduction: movement toward the median plan
Circular Movements
Rotation: turning of a structure on its long axis
- Examples: rotation of the head, humerus, entire body
- Medial and lateral rotation; example, the rotation of the arm
Pronation/Supination: refer to unique rotation of the forearm
- Pronation: palm faces posteriorly
- Supination: palm faces anteriorly
Circumduction
- Combination of flexion, extension, abduction, adduction
- Appendage describes a cone
Special Movements
Unique to only one or two joints Types - Elevation and Depression - Protraction and Retraction - Excursion - Opposition and Reposition - Inversion and Eversion
Elevation and Depression
Elevation: moves a structure superior
Depression: moves a structure inferior
Examples: shrugging the shoulders, opening and closing the mouth
Protraction and Retraction
Protraction: gliding motion anteriorly
Retraction: moves structure back to anatomic position or even further posteriorly
Examples: scapulae and mandibles
Excursion
Lateral: moving mandible to the right or left of midline
Medial: return the mandible to the midline
Opposition and Reposition
Opposition: movement of thumb and little finger toward each other
Re-position: return to anatomical position
Inversion and Eversion
Inversion: turning the ankle so the plantar surface of foot faces medially
Eversion: turning the ankle so the plantar surface of foot faces laterally
Range of motion
The amount of mobility at a give joint Active range of motion - Movement by normal contraction Passive range of motion - Movement by an outside source
Beyond Range of Motion
Dislocation (luxation) - Articulating surfaces out of alignment Subluxation - Partial dislocation Sprain - Ligaments are damaged
Effects of Aging on Joints
- Tissue repair slows; rate of new blood vessel development decreases
- Articular cartilages wear down and matrix becomes more rigid
- Production of synovial fluid declines
- Ligaments and tendons become shorter and less flexible: decrease in range of motion (ROM)
- Muscles around joints weaken
- A decrease in activity causes less flexibility and decreased ROM
