Chapter 8 - Joints Flashcards
Joints (Articulations) facts
- Functional connections between bones
- Bind parts of skeletal system together
- Make bone growth possible
- Permit parts of the skeleton to change shape during
childbirth - Enable body to move in response to skeletal muscle
contractions
Structural Classification of Joints:
- Fibrous: Held together by dense connective tissue
- Cartilaginous: Held together by cartilage
- Synovial: Have a complex structure
Functional Classification of Joints:
SAD
- Synarthrotic: Immovable
- Amphiarthrotic: Slightly movable
- Diarthrotic: Freely movable
Fibrous joints:
- Held together with dense connective tissue containing many
collagen fibers - Found in bones in close contact
What are the 3 types of Fibrous Joints?
- Syndesmosis
- Suture
- Gomphosis
Syndesmosis
- Bones bound by a sheet of dense connective tissue
(interosseous membrane) or a bundle of dense connective
tissue (interosseous ligament) - Amphiarthrotic (flexible, may twist)
- Between tibia and fibula
Suture
- Thin layer of connective tissue (sutural ligament) connects
bones - Synarthrotic (immovable) between flat bones of skull
Gomphosis
- Cone-shaped bony process in a socket
- Synarthrotic (immovable)
- Root of a tooth in maxilla or mandible held in place by
periodontal ligament
Cartilaginous joints:
Connected by hyaline cartilage or fibrocartilage.
What are the 2 types of cartilaginous joints?
- Synchondrosis
- Symphysis
Synchondrosis
- Bands of hyaline cartilage unite bones
- Synarthrotic
- Some are temporary, such as epiphyseal plate
(ossification converts this to a synostosis) - Some are permanent, such as between manubrium and
the first rib (costal cartilages)
Symphysis
- Pad of fibrocartilage between bones
- Articular surfaces covered by hyaline cartilage
- Amphiarthrotic (limited movement)
- Pubic symphysis
- Joint between bodies of adjacent vertebrae
(intervertebral discs)
Synovial Joints:
- Most joints are synovial joints
- All are diarthrotic joints
- Have a more complex structure than fibrous or
cartilaginous joints
Structure of a synovial joint:
Articular cartilage covers articular ends of bones
Joint capsule consists of 2 layers:
- Outer fibrous layer, composed of ligaments
- Inner layer, synovial membrane, which secretes synovial fluid
Synovial joints consist of the following parts:
- Articular cartilage
- Joint capsule
- Ligaments
- Synovial membrane
- Synovial cavity
- Synovial fluid
- Meniscus (-i) in some joints
- Bursa (-ae) in some joints
There are 6 types of synovial joints, classified by shape and
movements they allow:
Ball-and-Socket, condylar, plane, hinge, pivot, saddle
Ball-and-Socket Joint:
- Also called spheroidal joint
- Round head in cup-shaped cavity
- Widest range of motion
- Multiaxial, plus rotation
- Hip, shoulder
Condylar Joint:
- Also called ellipsoidal joint
- Oval condyle fits into elliptical cavity
- Back-and-forth, side-to-side movement
- Biaxial movement, no rotation
- Joints between metacarpals and phalanges
Plane Joint:
- Also called gliding joint
- Almost flat, or slightly curved
- Back-and-forth and twisting
- Nonaxial movement
- Wrist and ankle joints
Hinge Joint:
- Convex surface fits into concave surface of other bone
- Uniaxial movement (in 1 plane)
- Elbow, joints between phalanges
Pivot Joint:
- Also called trochoid joint
- Cylindrical surface rotates within ring of other bone
- Uniaxial movement
- Rotation only
- Atlas (C1) and dens of axis (C2)
Saddle Joint:
- Also called sellar joint
- Both bones have concave and convex surfaces
- Biaxial movement (in 2 planes)
- Carpal and metacarpal of thumb
Action of skeletal muscle produces…?
movement at synovial
joints
Types of Joint Movements: Origin…?
Relatively fixed end of a skeletal muscle
Types of Joint Movements: Insertion?
More movable end of a skeletal muscle
Movement at a joint occurs when…?
a muscle contracts, and
its fibers pull the insertion toward the origin
Flexion
Bending of parts at a joint
Extension
Straightening of parts at a joint
Hyperextension
Extension beyond normal anatomical
position
Lateral flexion:
Bending to the side
Abduction
Moving a part of body away from midline
Adduction
Moving a part of body toward midline
Dorsiflexion
Ankle movement which points toes upward
Plantar flexion:
Ankle movement which points toes downward
Circumduction
Movement of a part of body in circular path
Rotation
Moving a part of body around an axis
Medial rotation:
Movement of limb so anterior surface moves toward
midline
Lateral rotation:
Movement of limb so anterior surface moves away
from midline
Supination
Forearm rotation so palm faces upward or forward, or
lying down face up (supine)
Pronation
Forearm rotation so palm faces downward or backward, or
lying down face down (prone)
Inversion
Turning of foot so plantar surface faces
midline
Eversion
Turning of foot so plantar surface faces away
from midline
Protraction
Movement of a body part forward
Retraction
Movement of a body part backward
Elevation
raising a body partde
Depression
lowering a body part
What are Examples of large, complex synovial (also freely movable)
joints?
Shoulder, Elbow, Hip, Knee
Lifespan Changes
- Joint stiffness is an early sign of aging
- Many people develop arthritis as they age
- Fibrous joints first to change; can strengthen, however,
over a lifetime - Cartilage in synchondroses stiffens
- Ligaments lose elasticity
- Changes in symphysis joints of vertebral column diminish
flexibility and decrease height (due to water loss from the
intervertebral discs) - Synovial joints lose function, as capillary supply diminishes
- Disuse hampers the nutrient supply to joints; speeds up
stiffening - Activity and exercise can keep joints functional longer
