Anatomy and Physiology of Joints: Types, Movements, and Disorders

Joint

A joint is a point of contact between two or more bones, cartilage and bone, or teeth and bone.

Articulation

A joint is also called articulation or arthrosis.

Classification of Joints

Joints can be classified in two ways: structurally and functionally.

Structural Classification

This classification considers whether there is a joint cavity and the type of connective tissue involved.

Functional Classification

This classification considers the degree of movement permitted and the type of movement allowed.

Fibrous Joints

A type of joint where dense connective tissue connects bones.

Cartilaginous Joints

A type of joint where cartilage connects bones.

Synovial Joints

A type of joint characterized by a joint cavity filled with synovial fluid.

Temporomandibular Joint

A joint that connects the jawbone to the skull, allowing for movements such as opening and closing the mouth.

Shoulder Joint

A joint that connects the arm to the body, allowing for a wide range of motion.

Elbow Joint

A joint that connects the upper arm to the forearm, allowing for bending and straightening of the arm.

Hip Joint

A joint that connects the leg to the pelvis, allowing for movements such as walking and running.

Knee Joint

A joint that connects the thigh bone to the shin bone, allowing for bending and straightening of the leg.

Types of Movement at Synovial Joints

Includes gliding, angular movements, and special movements.

Aging and Joints

Aging can affect the structure and function of joints.

Arthroplasty

A surgical procedure to restore the function of a joint.

Hip Replacements

A type of arthroplasty procedure where the hip joint is replaced.

Knee Replacements

A type of arthroplasty procedure where the knee joint is replaced.

Rheumatism

A term used to describe various painful medical conditions affecting joints and connective tissues.

Arthritis

An inflammation of one or more joints, causing pain and stiffness.

Lyme Disease

An infectious disease caused by bacteria transmitted through tick bites, which can affect joints.

Sprain

An injury to a ligament caused by overstretching or tearing.

Strain

An injury to a muscle or tendon caused by overstretching or tearing.

Tenosynovitis

An inflammation of the sheath that surrounds a tendon.

Dislocated Mandible

A condition where the jawbone becomes displaced from its normal position.

Sutures

Dense irregular connective tissue.

Synchondroses

Hyaline cartilage.

Synostosis

Eg., frontal suture.

Epiphyseal cartilage

Hyaline cartilage.

Syndesmoses

More dense irregular connective tissue than a suture.

Symphysis

Fibrous cartilage.

Gomphosis

Eg., pubic symphysis and intervertebral joints.

Synarthroses

Immovable.

Amphiarthroses

Slightly movable.

Diarthroses

Freely movable.

Sutures (example)

Eg., suture.

Gomphosis (example)

Eg., gomphosis.

Pubic symphysis (example)

Eg., pubic symphysis.

Intervertebral discs (example)

Eg., intervertebral discs.

Syndesmosis

Articulating bones united by a varying amount of dense irregular connective tissue, usually a ligament or membrane.

Symphyses

Connecting material is fibrocartilage.

Cartilaginous Joint

No Articular Cavity; Articulating Bones United by Hyaline Cartilage or Fibrous Cartilage.

Synchondrosis

Connecting material: hyaline cartilage. Immovable to slightly movable.

Example of Synchondrosis

Between first rib and manubrium of sternum; Epiphyseal cartilage between diaphysis and epiphysis of long bone.

Example of Symphysis

Pubic symphysis and intervertebral joints.

Synovial Joint

Synovial joints have a synovial cavity, articulating bones are covered with articular cartilage, held together by ligaments, contain synovial fluid, have a nerve and blood supply, and are surrounded by an articular capsule.

Bursae

Sac-like structures filled with synovial fluid that cushion movement of one body part over another.

Tendon Sheaths

A tube-like bursae that wraps around tendons subject to a great deal of friction.

Gliding Movement

Movement of relatively flat bone surfaces back-and-forth and side-to-side over another; little change in angle between bones.

Angular Movement

Increase or decrease in angle between bones.

Flexion

Decrease in angle between articulating bones, usually in sagittal plane or an anterior movement at a ball-and-socket joint.

Lateral Flexion

Movement of trunk in frontal plane.

Extension

Increase in angle between articulating bones, usually in sagittal plane or a posterior movement at a ball-and-socket joint.

Abduction

Movement of bone away from midline, usually in coronal plane.

Adduction

Movement of bone toward midline, usually in coronal plane.

Circumduction

Flexion, abduction, extension, adduction, and rotation in succession (or in the opposite order); distal end of body part moves in circle.

Rotation

Movement of bone around longitudinal axis; in limbs, may be medial (toward midline) or lateral (away from midline).

Elevation

Superior movement of body part.

Depression

Inferior movement of body part.

Protraction

Anterior movement of body part in transverse plane.

Retraction

Posterior movement of body part in transverse plane.

Inversion

Medial movement of sole.

Eversion

Lateral movement of sole.

Dorsiflexion

Bending foot in direction of dorsum (superior surface).

Plantar Flexion

Bending foot in direction of plantar surface (sole).

Supination

Movement of forearm that turns palm anteriorly.

Pronation

Movement of forearm that turns palm posteriorly.

Opposition

Movement of thumb across palm to touch fingertips on same hand.

Plane Joint

Articulated surfaces flat or slightly curved. Example: Intercarpal, intertarsal, sternocostal, and vertebrocostal joints. Many are biaxial: back-and-forth and side-to-side movements. Some are triaxial: back-and-forth, side-to-side, rotation.

Hinge Joint

Convex surface fits into concave surface. Uniaxial: flexion-extension. Example: Elbow, ankle, and interphalangeal joints. Uniaxial: rotation. Example: Atlanto-axial and radioulnar joints.

Pivot Joint

Rounded or pointed surface fits into ring formed partly by bone and partly by ligament.

Ellipsoid (Condyloid) Joint

Oval-shaped projection fits into oval-shaped depression. Example: Radiocarpal and metacarpophalangeal joints. Biaxial: flexion-extension, abduction-adduction.

Saddle Joint

Articular surface of one bone is saddle-shaped; articular surface of other bone 'sits' in saddle.

Ball-and-Socket Joint

Ball-like surface fits into cuplike depression. Example: Glenohumeral and hip joints. Triaxial: flexion-extension, abduction-adduction, rotation.

Factors Affecting Contact and Range of Motion at Synovial Joints

1. Structure and shape of the articulating bones. E.g., hip joint. 2. Strength and tension (tautness) of the joint ligaments. E.g., knee joint. 3. Arrangement and tension of the muscles. E.g., hip joint. 4. Contact of soft parts. E.g., elbow joint. 5. Hormones. E.g., relaxin, a hormone released by the placenta and ovaries, increases the flexibility of the fibrocartilage of the pubic symphysis and loosens the ligaments between the sacrum, hip bone, and coccyx towards the end of pregnancy. 6. Disuse. Disuse of a joint for an extended period may limit the range of motion of that joint. Disuse may also result in decreased amount of synovial fluid, diminished flexibility of ligaments and tendons, and muscular atrophy (reduction in size or wasting of a muscle).

Suture Joint

Between skull bones. Fibrous. None.

Atlanto-occipital Joint

Between superior articular facets of atlas and occipital condyles of occipital bone. Synovial (ellipsoid). Flexion and extension of head; slight lateral flexion of head to either side.

Atlanto-axial Joint

(1) Between dens of axis and anterior arch of atlas; (2) between lateral masses of atlas and axis. Synovial (pivot) between dens and anterior arch; synovial (planar) between lateral masses.

Intervertebral Joint

(1) Between vertebral bodies; (2) between vertebral arches.

Intervertebral

(1) Between vertebral bodies; (2) between vertebral arches.

Movements of Intervertebral Joints

Flexion, extension, lateral flexion, and rotation of vertebral column.

Classification of Intervertebral Joints

Cartilaginous (symphysis) between vertebral bodies; synovial (planar) between vertebral arches.

Vertebrocostal

(1) Between articular facets of heads of ribs and costal facets of bodies of adjacent thoracic vertebrae and intervertebral discs between them; (2) between articular facet of tubercles of ribs and transverse costal facet of thoracic vertebrae.

Classification of Vertebrocostal Joints

Synovial (planar). Slight gliding.

Suture

Between skull bones. Fibrous. None.

Sternocostal

Between sternum and first seven pairs of ribs.

Movements of Sternocostal Joints

None between sternum and first pair of ribs; slight gliding between sternum and second through seventh pairs of ribs.

Classification of Sternocostal Joints

Cartilaginous (synchondrosis) between sternum and first pair of ribs; synovial (plane) between sternum and second through seventh pairs of ribs.

Lumbosacral

(1) Between body of fifth lumbar vertebra and base of sacrum; (2) between inferior articular facets of fifth lumbar vertebra and superior articular facets of first vertebra of sacrum.

Movements of Lumbosacral Joints

Flexion, extension, lateral flexion, and rotation of vertebral column.

Classification of Lumbosacral Joints

Cartilaginous (symphysis) between body and base; synovial (planar) between articular facets.

Sternoclavicular

Between sternal end of clavicle, manubrium of sternum, and first costal cartilage.

Classification of Sternoclavicular Joints

Synovial (plane, pivot). Gliding, with limited movements in nearly every direction.

Acromioclavicular

Between acromion of scapula and acromial end of clavicle.

Classification of Acromioclavicular Joints

Synovial (plane). Gliding and rotation of scapula on clavicle.

Radioulnar

Proximal radioulnar joint between head of radius and radial notch of ulna; distal radioulnar joint between ulnar notch of radius and head of ulna.

Wrist (radiocarpal)

Between distal end of radius and scaphoid, lunate, and triquetrum of carpus.

Classification of Wrist Joints

Synovial (ellipsoid).

Movements of Wrist Joints

Flexion, extension, abduction, adduction, circumduction, and slight hyperextension of wrist.

Intercarpal

Between proximal row of carpal bones, distal row of carpal bones, and between both rows of carpal bones (midcarpal joints).