Articulations and Body Movements Flashcards
Articulations
Joints that hold bones together and allow the rigid skeletal system some flexibility so that gross body movements can occur
Structural classifications of joints
Fibrous, cartilaginous and synovial joints
Functional classifications of joints
Synarthroses, amphiarthroses, diarthroses
Synarthroses
Immovable joints
Amphiarthroses
Slightly movable joints
Diarthroses
Freely movable joints
Where do diarthroses joints predominate?
In the limbs
Where do synarthroses and amphiarthroses joints predominate?
Restricted to the axial skeleton, where firm bony attachments and protection of enclosed organs are priorities
General rule about fibrous and synovial joints
Fibrous joints are immovable and synovial joints are feely movable
General rule about cartilaginous joints
Offers both rigid and slightly movable examples
Fibrous joints
Bones joined by fibrous tissue, no joint cavity is present. Amount of movement depends on length of fibers uniting bones. Some are slightly movable, most are synarthrotic and permit virtually no movement.
2 major types of fibrous joints
Sutures and syndesmoses
Sutures
Irregular edges of the bones interlock and are united by very short connective tissue fibers
Syndesmoses
Articulating bones are connected by short ligaments of dense fibrous tissue; bones do not interlock.
Cartilaginous joints
The articulating bone ends are connected by a plate or pad of cartilage. No joint cavity is present. Most are slightly movable (amphiarthrotic)
2 major types of cartilaginous joints
Synchondroses and symphyses
Symphyses
Bones are connected by a broad, flat disc of fibrocartilage. i.e. intervertebral joints and pubic symphysis
Synchondroses
Bony portions are united by hyaline cartilage. i.e. articulation of costal cartilage of the ribs to the sternum
Synovial joints
Articulating bone ends are separated by a joint cavity containing synovial fluid. All are diarthroses (freely movable)
Movement of Synovial joints
All are freely movable joints (diarthroses) but mobility varies: some synovial joints permit only small gliding movements, and others can move in several planes.
Structural characteristics of synovial joints
- Enclosed by a 2-layered articular capsule, creating a joint cavity.
- Inner layer is smooth CT membrane (synovial membrane) producing lubricating fluid to reduce friction. Outer layer dense irregular CT
- Articular (hyaline) cartilage covers surfaces of the bones forming a joint
- Articular capsule typically reinforced with ligaments and may contain bursae
- Fibrocartilage pads (articular discs) may be present within capsule
What determines the types of movements that can occur at the joint and the structural classification of the joints?
The shapes of the articular surfaces
Plane (Nonaxial) joint
Articulating surfaces are flat or slightly curved. Allow only gliding movements as the surfaces slide past one another.
Example of Plane (nonaxial) joint
Intercarpal joints, intertarsal joints, and joints between vertebral articular surfaces
Hinge (Uniaxial) joint
The rounded or cylindrical process of one bone fits into the concave surface of another bone, allowing movement in one plane, usually flexion and extension.
Example of Hinge (uniaxial) joint
Elbow and interphalangeal joints
Pivot (Uniaxial) joint
The rounded surface of one bone articulates with a shallow depression or foramen in another bone, permitting rotational movement in one plane.
Example of Pivot (uniaxial) joint
Proximal radioulnar joint and atlantoaxial joint (between C1 and C2).
Condylar (Biaxial) joint
The oval condyle of one bone fits into an ellipsoidal depression in another bone to allow movement in two planes, usually flexion/extension and abduction/adduction.
Example of Condylar (biaxial) joint
Wrist and metacarpophalangeal (knuckle) joints
Saddle (Biaxial) joint
Articulating surfaes are saddle shaped; one surface is convex, and the other is concave. Permits movement in two planes, flexion/extension and abduction/adduction
Example of Saddle (biaxial) joint
Carpometacarpal joints of the thumb
Ball-and-socket (multiaxial) joint
Ball-shaped head of one bone fits into a cup like depression of another bone. Permits flexion/extension, abduction/adduction, and rotation, which combine and allow movement in many planes.
Example of Ball-and-socket (multiaxial) joint
Shoulder and hip
Origin
The stationary, immovable, or less movable attachment
Insertion
The movable attachment
How does body movement occur?
When muscles contract across diarthrotic synovial joints and the insertion moves towards the origin
What does the type of movement depend on?
The construction of the joint and on the placement of the muscle relative to the joint
Flexion
Movement generally in sagittal plane, that decreases the angle of the joint and reduces the distance between the two bones.
What joints are typical of flexion?
Hinge joints (bending knee or elbow) but also common at ball-and-socket joints (bending forward at the hip)
Extension
Movement increases the angle of a joint and the distance between two bones or parts of the body (straightening the knee or elbow); opposite of flexion.
Hyperextension
if extension proceeds beyond anatomical position (bends trunk backward)
Abduction
Movement of limb away from midline or median plane of body, generally on the frontal plane, or the fanning movement of fingers or toes when they are spread apart
Adduction
Movement of limb toward the midline of the body or drawing the fingers or toes together. Opposite of abduction
Rotation
Movement of a bone around its longitudinal axis without lateral or medial displacement.
What joints are typical of rotation?
Ball-and-Socket joints and the movement of the atlas around the dens of the axis
Circumduction
A combination of flexion, extension, abduction, and adduction commonly observed in ball-and-socket joints like the shoulder. Proximal end of the lib remains stationary, and the distal end moves in a circle.
What joints are typical of circumduction?
Ball-and-socket mainly but condylar and saddle joints also allow circumduction
Pronation
Movement of the palm of the hand from an anterior or upward-facing position to a posterior or downward-facing position. Distal end of radius moves across the ulna forming an X
Supination
Movement of the palm from a posterior position to an anterior position (anatomical position); opposite of pronation. Radius and ulna are parallel.
Dorsiflexion
Movement of the ankle joint that lifts the foot so that its superior surface approaches the shin
Pantar flexion
Movement of the ankle joint in which the foot is flexed downward as if standing on one’s toes or pointing the toes
Inversion
Movement that turns the sole of the foot medially
Eversion
Movement that turns the sole of the foot laterally; opposite of inversion
