Joints

Articulations Joint A point of contact between two bones, between bone and cartilage, or between bone and teeth

Structural Classification Presence of synovial cavity? Type of connective tissue?

Types of Joints based on Structure Fibrous Cartilaginous Synovial

Fibrous Fibrous connective tissue Lack a synovial cavity

Cartilaginous Cartilage Lack a synovial cavity

Synovial Dense irregular connective tissue Acessory ligaments Synovial Cavity present

Functional Classification Degree of movement they permit

Type of Joints Based on Function Synarthrosis Amphiarthrosis Diarthrosis

Synarthrosis Immovable joint

Amphiarthrosis Slightly movable joint

Diarthrosis Freely movable joints All are synovial joints

Three types of Fibrous Joints Sutures Syndesmoses Gomphoses

Suture A fibrous joint composed of dense fibrous connective tissue that unite skull bones only.

Suture Synarthrosis (immovable)

Suture Example: coronal suture

Syndesmoses A fibrous joint

Syndesmoses More distance between bones than sutures

Syndesmoses Fibrous connective tissue arranged as a ligament (bundle) or interosseous membrane (sheet)

Syndesmoses Amphiarthrosis (slightly movable)

Syndesmoses Example: distal tibiofibular joint

Gomphosis A fibrous joint in which a cone-shaped peg fits into a socket

Gomphosis Articulation between roots of teeth and sockets of the maxillae and mandible.

Gomphosis Dense fibrous connective tissue is the periodontal ligament

Gomphosis Synarthrosis (immovable joint)

Types of Cartilaginous Joints Synchondroses Symphyses

Synchondroses Hyaline cartilage

Synchondroses Synarthrosis (immovable joint)

Synchondroses Example: epiphyseal plate and first rib and manubrium of sternum

Symphyses Fibrocartilage connects the bones

Symphyses Amphiarthrosis (slightly movable)

Symphyses Example: pubic symphysis

Synovial Joints All diarthrosis

Synovial Joints Contain Synovial Cavity (presence of space between articulating bones)

Synovial Joints Ends of bones covered by articular cartilage

Articular Capsule of Synovial Joints Encloses the synovial cavity and unites the articulating bones

Articular Capsule of Synovial Joints Fibrous capsule – outer layer composed of dense connective tissue

Articular Capsule of Synovial Joints Synovial membrane – inner layer composed of areolar connective tissue

Synovial Fluid of the Synovial Joint Fluid in the joint cavity secreted by fibroblasts of the synovial membrane

Synovial Fluid of the Synovial Joint Reduces friction

Synovial Fluid of the Synovial Joint 2. Supplies nutrients and removes wastes from chondrocytes within articular cartilage

Accessory Ligaments of the Synovial Joint Extracapsular ligaments – lie outside the articular capsule (Fibular and Tibular Collateral Ligaments)

Accessory Ligaments of the Synovial Joint Intracapsular ligaments – occur within the articular capsule (Anterior and Posterior Cruciate Ligament)

Articular Discs of Synovial Joints Fibrocartilage that lie between the articular surfaces of the bones

Articular Discs of Synovial Joints Allow two bones of different shapes to fit more tightly

Articular Discs of Synovial Joints Directs flow of synovial fluid to the areas of greatest friction

Types of Synovial Joints Planar Hinge Pivot Condyloid Saddle Ball and Socket

Planar Articulating surfaces are flat or slightly curved

Planar Permits side to side and back and forth gliding movement

Planar Example: intercarpal, intertarsal, sternoclavicle, acromioclavicular, sternocostal, vertebrocostal

Hinge Convex surface of one bone fits into the concave surface of another bone

Hinge Monoaxial

Hinge Examples: knee, elbow, ankle, and interphalangeal

Pivot Rounded or pointed surface of one bone articulates with a ring formed by another bone and ligament

Pivot Monoaxial

Pivot Example: radioulnar joint

Condyloid Convex oval-shaped projection of one bone fits into the oval-shaped depression of another bone

Condyloid Biaxial

Condyloid Example: wrist and metacarpophalangeal joints

Saddle Articular surface of one bone is saddle shaped, and the other bone fits into the saddle

Saddle Biaxial

Saddle Example: carpometacarpal joint of the thumb

Ball and Socket Consists of the ball-like surface of one bone fits into a cup-like depression of another bone

Ball and Socket Multiaxial

Ball and Socket Example: shoulder and hip joints

Torn Cartilage The tearing of articular discs or menisci in the knee. Occurs among athletes

Sprains This occurs when a joint is twisted and stretches or tears its ligaments but does not dislocate the bones.

Sprains Ankle joint and lower back are commonly sprained

Dislocation The displacement of a bone from joint, with resultant tearing of ligaments, tendons, and articular capsules

Dislocation The shoulder joint is the most common joint dislocated due to shallowness of the socket.

Dislocation Hip joint not common due to acetabular rim is smaller than the head of the femur

Shoulder Joint Glenohumeral joint

Shoulder Joint Ball and socket joint

Shoulder Joint Head of the humerus and glenoid cavity of the scapula

Shoulder Joint / Anatomical Features Glenoid labrum – A narrow rim of fibrocartilage around the edge of the glenoid cavity.

Shoulder Joint / Anatomical Features Glenoid labrum deepens and enlarges the glenoid cavity

Shoulder Joint / Anatomical Features Bursae – fluid filled saclike structures that reduce friction in synovial joints

Shoulder Joint / Movements Flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumduction

Shoulder Joint / Strength Attains most support from the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) which join the scapula to the humerus

Shoulder Joint / Strength Rotator cuff muscles hold the head of the humerus in the glenoid cavity

Elbow Joint Hinge joint

Elbow Joint Involves the trochlea of the humerus, the trochlear notch of the ulna, and the head of the radius

Elbow Joint / Movements Flexion and extension

Hip Joint Ball and socket

Hip Joint Head of the femur and the acetabulum of the hip bone

Hip Joint / Anatomical Features Acetabular labrum – Fibrocartilage rim attached to the margin of the acetabulum.

Hip Joint / Anatomical Features Acetabular labrum enhances the depth of the acetabulum

Hip Joint / Movements Flexion, extension, abduction, adduction, circumduction, medial rotation, and lateral rotation of the thigh

Knee Joint One synovial cavity

Knee Joint 3 joints

Knee Joint 1. Tibiofemoral joint – hinge joint/ between the lateral condyle of the femur, lateral meniscus, and lateral condyle of the tibia

Knee Joint 2. Tibiofemoral joint – hinge joint/ between the medial condyle of the femur, medial meniscus, and medial condylye of the tibia

Knee Joint 3. Patellofemoral joint – planar joint/ between the patella and the patellar surface of the femur

Knee Joint / Anatomical Features Medial meniscus and Lateral meniscus

Knee Joint / Anatomical Features Contains bursae

Knee Joint Flexion, extension, slight medial rotation, lateral rotation of leg in flexed position