Chapter 8 – Joints (Articulations)

These flashcards cover key definitions, classifications, and examples related to joints (articulations) as discussed in Chapter 8.

Joint (articulation)

The site where two or more bones meet.

Functions of joints

Provide mobility and hold the skeleton together.

Structural classifications of joints

Fibrous, cartilaginous, and synovial.

Functional classifications of joints

Synarthroses (immovable), amphiarthroses (slightly movable), diarthroses (freely movable).

Classification system most often used

Structural classification.

Fibrous joints connection

Dense fibrous connective tissue.

Do fibrous joints have a joint cavity?

No.

Mobility of fibrous joints

Most are immovable.

Types of fibrous joints

Sutures, syndesmoses, and gomphoses.

Where are sutures found?

Between bones of the skull.

What happens to sutures with age?

They ossify and become synostoses.

Connection in syndesmoses

Ligaments.

Effect of fiber length in syndesmoses

Short fibers = little movement; long fibers = more movement.

Example of a short syndesmosis

Distal tibiofibular joint.

Example of a long syndesmosis

Interosseous membrane between radius and ulna.

Gomphosis

A peg-in-socket fibrous joint.

Only gomphosis in the body

Teeth in alveolar sockets.

Ligament anchoring a tooth

Periodontal ligament.

Connection in cartilaginous joints

Cartilage.

Do cartilaginous joints have a cavity?

No.

Types of cartilaginous joints

Synchondroses and symphyses.

Cartilage forming a synchondrosis

Hyaline cartilage.

Mobility of synchondroses

Mostly immovable (synarthrotic).

Examples of synchondroses

Epiphyseal plate and first rib–manubrium junction.

Cartilage forming a symphysis

Fibrocartilage.

Mobility of symphyses

Slightly movable (amphiarthrotic).

Examples of symphyses

Intervertebral discs and pubic symphysis.

Connection in synovial joints

A joint cavity filled with synovial fluid.

Mobility of synovial joints

Yes, they are all freely movable (diarthrotic).

Covers bone ends in a synovial joint

Articular (hyaline) cartilage.

Enclosure of a synovial joint

A joint (articular) capsule.

Layers of the articular capsule

Outer fibrous layer and inner synovial membrane.

What does the synovial membrane produce?

Synovial fluid.

Function of synovial fluid

Lubricates, nourishes cartilage, and removes debris.

Outer capsule layer CT type

Dense irregular connective tissue.

Reinforcing ligaments

Ligaments that strengthen and support the joint.

Types of reinforcing ligaments

Capsular, extracapsular, and intracapsular.

Cushioning structures in joints

Fat pads and articular discs (menisci).

Bursae

Flattened sacs filled with synovial fluid that reduce friction.

Tendon sheaths

Elongated bursae that wrap around tendons.

Are bursae and tendon sheaths part of the joint?

No, but they are closely associated with it.

Factors determining joint stability

Articular surface shape, ligaments, and muscle tone.

Most important stability factor

Muscle tone.

Types of movement axes

Nonaxial, uniaxial, biaxial, and multiaxial.

Movement involving flat surfaces gliding

Gliding.

Examples of gliding joints

Intercarpal, intertarsal, and vertebral facet joints.

Movement decreasing the angle between bones

Flexion.

Movement increasing the angle between bones

Extension.

Hyperextension

Extension beyond anatomical position.

Abduction

Moving away from the midline.

Adduction

Moving toward the midline.

Circumduction

Movement that traces a cone-shaped path.

Rotation

Bone turning around its long axis.

Supination

Turning the palm upward.

Pronation

Turning the palm downward.

Dorsiflexion

Lifting the foot toward the shin.

Plantar flexion

Pointing the toes downward.

Inversion and eversion

Inversion = sole inward; Eversion = sole outward.

Elevation

Lifting a body part upward.

Depression

Lowering a body part downward.

Protraction

Moving a body part forward.

Retraction

Moving a body part backward.

Structural types of synovial joints

Plane, hinge, pivot, condylar, saddle, ball-and-socket.

Example of a plane joint

Intercarpal or intertarsal joint.

Example of a hinge joint

Elbow or interphalangeal joint.

Example of a pivot joint

Atlas–axis or proximal radioulnar joint.

Example of a condylar joint

Wrist or knuckle.

Example of a saddle joint

Thumb carpometacarpal joint.

Example of a ball-and-socket joint

Shoulder and hip joints.

Most movable joint in the body

Shoulder (glenohumeral) joint.

Fibrocartilage rim deepening the shoulder socket

Glenoid labrum.

Muscle group stabilizing the shoulder joint

Rotator cuff (SITS: supraspinatus, infraspinatus, teres minor, subscapularis).

Type of joint at the elbow

Hinge joint.

Ligaments stabilizing the elbow

Ulnar collateral, radial collateral, and annular ligament.

Type of joint at the hip

Ball-and-socket joint.

Ligaments strengthening the hip

Iliofemoral, pubofemoral, ischiofemoral, and ligamentum teres.

Type of joint at the knee

Modified hinge joint.

Ligaments stabilizing the knee

ACL, PCL, tibial & fibular collateral ligaments, oblique & arcuate popliteal ligaments.

Unhappy Triad of knee injuries

Torn ACL, tibial collateral ligament, and medial meniscus.

Osteoarthritis

Chronic 'wear-and-tear' degeneration of articular cartilage.