Anatomy of Joints and Synarthrosis

Joints

• Joints enable movement between bones
• They classified by the type of tissue connecting the bones
• Joints without movement or with limited movement are called synarthrosis

Synarthrosis

• Suture: A thin layer of dense connective tissue connecting the bones of the skull
• Examples: Coronal or lambdoid suture
• Gomphosis: Microscopic ligaments in dental alveoli attaching teeth to their sockets
• Syndesmosis: Dense connective tissue ligament or sheet connecting bones, allowing limited movement
• Examples: Coracoclavicular ligament, interosseous membrane between tibia and fibula
• Synchondrosis: Bones held together by hyaline cartilage
• Examples: Sphenopetrosal synchondrosis
• Symphysis: Bones held together by fibrous cartilage
• Examples: Intervertebral disks
• Hemidiarthrosis: A specialized form with a gap in fibrous cartilage, representing a transition towards synovial joints
• Examples: Pubic symphysis
• Synostosis: Fusion of two or more bones into one
• Examples: hip bone, sacrum

Diarthrosis

• Also known as synovial joint or articulation
• Allows a wide range of movements
• Contains a joint cavity between articulating bones
• Main components:
  • Articular cartilage on the articular surface of bones
  • Ligaments
  • Joint capsule
  • Synovial membrane and the fluid it produces (synovia), which fills the joint cavity

Accessory Components of Diarthrosis

• Articular disks and menisci (meniscus): Found in some joints
• Articular labrum (lip): Found in some joints
• Bursae and synovial tendon sheaths: Found in some joints

Diarthrosis Movement Types

• Plane joint (Amphiarthrosis): No defined axis for movement
• Uniaxial joint: Movement occurs around one axis
• Biaxial joint: Movement occurs around two axes
• Multiaxial joint: Movement occurs around multiple axes
• The axis of a joint is always perpendicular to the plane of its movement

Uniaxial Joints

• Hinge (Ginglymus): Allows flexion and extension
• Pivot (Trochoid): Allows rotation
• Trochoginglymus: Combines hinge and pivot movements; found in the elbow joint

Biaxial Joints

• Ellipsoid (Condyloid): Allows flexion-extension and abduction-adduction
• Saddle (Sellaris): Allows flexion-extension, abduction-adduction, and rotation

Multiaxial Joints

• Ball and socket (Spheroid): Allows movement in all planes
• Enarthrosis: Socket covers the sphere beyond its equator

Shoulder Girdle Joints

• Sternoclavicular and acromioclavicular joints form a bridge attaching the upper limb to the trunk
• Sternoclavicular joint: Saddle joint by shape, ball-and-socket joint by function
• Movements: Elevation-depression, protraction-retraction, rotation

Elbow Joint

• Composed of:
  • Humeroulnar joint (hinge or ginglymus): Trochlea of humerus -> Trochlear notch of ulna
  • Humeroradial joint (ball and socket): Capitulum of humerus -> Radial head
  • Proximal radioulnar joint (pivot or trochoid): Articular circumference of radius -> Radial notch of ulna
• Movement: Flexion-extension, supination-pronation
• Key structures: Annular ligament, collateral ligaments

Wrist Joint

• Radiocarpal (wrist) joint: Ellipsoid (Condyloid) type of joint
• Articulates with carpal articular surface of radius and three carpal bones of proximal row
• Movements: Palmarflexion-dorsalflexion, ulnar abduction-radial abduction, circumduction

Intercarpal Joints

• Plane type joints between carpal bones
• Held together by a common joint capsule

Carpometacarpal (CMC) Joint of Thumb

• Saddle type of joint
• Articulates with trapezium
• Movements: Abduction-adduction, flexion-extension, opposition-reposition

Carpometacarpal (CMC) Joints

• Located between carpal bones and bases of metacarpal bones
• Plane type joints

This quiz covers the anatomy of joints, focusing on their classification and types of connective tissue. Learn about different forms of synarthrosis such as sutures, gomphosis, and syndesmosis, along with their specific examples. Test your knowledge on how these joints contribute to movement and stability in the body.