Comprehensive Guide to Joints: Types, Movements, and Disorders in Anatomy

Joints

AKA - Articulation or arthrosis

Functional Classification

Based on the type of movement they permit

Synarthrosis

An immovable joint

Amphiarthrosis

A slightly movable joint

Diarthrosis

A freely movable joint; all are synovial joints

General morphology or Structural Classification

Anatomical characteristics; presence or absence of space between articulating bones (synovial cavity); type of connective tissue that binds the bones together

Fibrous

No synovial cavity; bones held together by dense collagen fibers

Cartilaginous

No synovial cavity; bones held together by cartilage

Synovial

Have a synovial cavity; united by dense irregular connective tissue of articular capsule; bones held together by ligaments

Fibrous Joints

Lack a synovial cavity; the articulating bones are held very closely together by dense irregular connective tissue; permit little or no movement

Sutures

Occur only between bones of the skull; adult = immovable; infants & children = slightly moveable

Gomphosis

Immovable joint; joint in which a cone-shaped peg fits into a socket; articulations of the teeth with the sockets of the maxillae and mandible

Syndesmoses

2 bones bound by an interosseous membrane; slight movement (amphiarthrosis); between the tibia and fibula in the leg

Cartilaginous Joints

No synovial cavity, allows little or no movement, held together by hyaline cartilage or fibrocartilage.

Synchondroses

Connecting tissue is hyaline cartilage, immovable, includes the epiphyseal (growth) plate.

Symphyses

Slightly movable joint where ends of articulating bones are covered with hyaline cartilage and connected by a disc of fibrocartilage.

Pubic Symphysis

Example of a symphysis located between the anterior surfaces of the hip bones.

Intervertebral joints

Example of a symphysis located between the vertebrae.

Articular Cartilage

Reduces friction between bones during movement and helps absorb shock.

Synovial Fluid

Secreted by the synovial membrane, contains hyaluronic acid, reduces friction, absorbs shocks, supplies oxygen and nutrients to cartilage, and removes carbon dioxide and metabolic wastes.

Articular Capsule

A sleeve-like capsule enclosing the synovial cavity, composed of an outer fibrous capsule and an inner synovial membrane.

Ligaments

Fibrous membranes arranged as parallel bundles of dense regular connective tissue that hold bones together in a synovial joint.

Articular Fat Pad

Adipose tissue located between the fibrous capsule and synovial membrane.

Infrapatellar fat pad

Example of an articular fat pad.

Bursa

Fibrous, slightly flattened sacs lined with synovial membrane, found between skin, tendons, muscles, and ligaments, providing cushioning.

Tendon Sheaths

Elongated bursa that wrap around tendons to reduce friction.

Accessory Ligaments

Extracapsular ligaments located outside of the articular capsule, such as the collateral ligaments of the knee.

Intracapsular ligaments

Ligaments located within the articular capsule but excluded from the synovial cavity by folds of synovial membrane, such as the ACL and PCL.

Articular Discs or Menisci

Pads of fibrocartilage between articular surfaces that function in shock absorption, better fit, adapting surfaces for combined movements, and weight distribution.

Labra

Fibrocartilaginous lip that extends from the end of a socket, deepening the joint socket and increasing area of contact.

Nerve endings

Convey information about pain from the joint to the spinal cord and brain, responding to the degree of movement and stretch at a joint.

Types of Synovial Joints

Classified into uniaxial, biaxial, and multiaxial types.

Uniaxial Joints

Include hinge, planar, and pivot joints.

Hinge Joints

Produce an opening and closing motion like that of a hinged door, permitting only flexion and extension, such as the elbow.

Planar Joints

Flat surfaces that primarily permit back-and-forth and side-to-side movements, such as intercarpal joints.

Pivot Joints

Surface of one bone articulates with a ring formed partly by another bone, enabling the palms to turn anteriorly and posteriorly, such as the superior radioulnar joint.

Biaxial Joints

Include condyloid and saddle joints.

Condyloid Joints

The projection of one bone fits into the oval-shaped depression of another bone, such as the wrist.

Saddle Joints

Articular surface of one bone is saddle-shaped, fitting into the saddle of another bone, such as the thumb.

Multiaxial Joints

Include ball-and-socket joints.

Ball-and-Socket Joints

Ball-like surface of one bone fitting into a cuplike depression of another bone, such as the shoulder and hip.

Types of Movement @ Synovial Joints

Grouped into four main categories: Gliding, Angular movements, Rotation, and Special movements.

Gliding

Simple movement back-and-forth and from side-to-side with no significant alteration of the angle between the bones, limited in range, such as intercarpal joints.

Angular Movements

Increase or decrease in the angle between articulating bones, including flexion, extension, hyperextension, lateral flexion, abduction/adduction, and circumduction.

Flexion

Decrease in the angle between articulating bones

Extension

Increase in the angle between articulating bones

Hyperextension

Continuation of extension beyond the normal extension

Lateral flexion

Movement of the trunk sideways to the right or left at the waist

Abduction

Movement of a bone away from the midline

Adduction

Movement of a bone toward the midline

Circumduction

Movement of a body part in a circle

Rotation

A bone revolves around its own longitudinal axis

Elevation

Upward movement of a part of the body

Depression

Downward movement of a part of the body

Protraction

Movement of a part of the body anteriorly

Retraction

Movement of a protracted part of the body back to normal

Inversion

Movement of the foot medially

Eversion

Movement of the sole laterally

Dorsiflexion

Bending of the foot at the ankle in an upward direction

Plantar flexion

Bending of the foot at the ankle in a downward direction

Supination

Movement of the forearm so that the palm is turned upward

Pronation

Movement of the forearm so that the palm is turned downward

Opposition/Reposition

Movement of the thumb in which the thumb moves across the palm to touch the tips of the fingers on the same hand

Rheumatoid Arthritis

Autoimmune disorder causing cartilage attack, inflammation, swelling & pain

Osteoarthritis

Degenerative joint disease characterized by aging and wear & tear

Gouty Arthritis

Condition where urate crystals build up in joints causing pain

Arthroplasty

Surgical replacement of joints with artificial joints

Hip Replacements

Partial or total replacement of the hip joint

Knee Replacements

May be partial or total replacement of the knee joint

Structural Classification

Based on anatomical characteristics and presence or absence of space between articulating bones (synovial cavity)

Synovial Joints

Have a synovial cavity; united by dense irregular connective tissue of articular capsule

Synchondrosis

Connecting tissue is hyaline cartilage; immovable

Gliding Movement

Simple movement back-and-forth and from side-to-side without significant alteration of the angle between the bones

Gliding Movements

Simple movement back-and-forth and from side-to-side without significant alteration of the angle between the bones