Joints/Ligaments Lecture

Joints

• Joints (aka articulations or arthroses) occur when two or more bones meet

Joints may permit:

• Slight movement or none

  • Such joints common in axial skeleton

• Extensive movement

  • Such joints common on appendicular skeleton

Bones forming joints may be in direct contact with each other or separated by:

• Cartilage

• Fluid

• Fibrous tissue

Classification of Joints

Joints are classified based on:

• Function

  • Functional categories of joints are based on Range of Motion (ROM) permitted by joint

• Structure

  • Structural categories of joints are based on their structural makeup

Functional classification of Joints

Joints can be classified based on their range of motion (function)

Synarthrosis

• Immovable

• Bony edges are quite close together

• E.g. skull sutures

Amphiarthrosis

• Joint permits little movement

• Bones in joint are slightly farther apart

Diarthrosis

• Freely movable and bones farther apart

• Bony surfaces in joint covered by hyaline cartilage

SYNARTHROSIS (NO MOVEMENT)

Fibrous

• Suture: Fibrous connections plus extensive interlocking

  • Ex. Between the bones of the skull

• Gomphosis: Fibrous connections plus insertion in alveolar process

  • Ex. Periodontal ligaments between the teeth and

SYNARTHROSIS (NO MOVEMENT)

Cartilaginous

• Interposition of cartilage plate

  • ex. Epiphyseal cartilages

SYNARTHROSIS (NO MOVEMENT)

Bony fusion

• Synostosis: Conversion of other articular form to a solid mass of bone

  • ex. Portions of the skull, such as along the frontal suture; epiphyseal lines

AMPHIARTHROSIS (LITTLE MOVEMENT)

Fibrous

• Syndesmosis: Ligamentous connection

  • ex. between the tibia and fibula

AMPIARTHROSIS (LITTLE MOVEMENT)

Cartilaginous

• Symphysis: connection by a pad of fibrous cartilage

  • ex. between right and left hip bones of pelvis, between adjacent vertebral bodies

DIATHROSIS (FREE MOVEMENT)

Synovial Monaxial Biaxial Triaxial	Complex joint bounded by joint capsule and containing synovial fluid Permits movement in one plane Permits movement in two planes Permits movement in all three planes	Numerous; subdivided by range of movement (see Figures 8.3 and 8.6) Elbow, ankle Ribs, wrist Shoulder, hip

Diarthroses (freely movable joints)

• Also called synovial joints

• Typically found at the ends of long bones

• Examples of diarthroses:

  • Shoulder joint

  • Hip joint

  • Elbow joint

  • Knee joint

  • Ankle joint

  • Wrist joint

Synovial joint

• Synovial Fluid:

  • Lubricates the surfaces of the articular cartilages and reduces friction

  • Nourishes the chondrocytes by entering and exiting the articular cartilages due to the forces acting on the joint

  • Acts as a shock absorber

• Bursae:

  • Sac like structures to reduce friction betweenbone and overlying tissues

• Articular cartilage has no perichondrium

Types of Movement of synovial joints

• Usually described with body in anatomical position

  • Linear movements

  • Angular movements

  • Rotation

  • Special movements

Linear movements

• Two bones gliding past each other

• Can occur in any direction

• Amount of movement is slight

• Examples include:

  • carpal/carpal

  • tarsal/tarsal

  • clavicle/sternum

Angular movements

• Abduction:

  • Movement away from longitudinal axis of the body in the frontal plane

• Adduction:

  • Movement toward longitudinal axis of the body in the frontal plane

• Flexion:

  • Movement in the anterior/posterior plane that reduces angle between articulating elements

• Extension:

  • Movement in the anterior/posterior plane that increases angle between articulating element

Rotational movements

• Left/right rotation of head while saying no

• Internal (medial) rotation of limb

• External (lateral rotation of limb)

• pronation/supination of palm

Special movements

• inversion/eversion of foot

• dorsiflexion/plantar flexion of foot

Lateral flexion

When vertebral column bends to side

Protraction

• Moving part of the body anteriorly in horizontal plane.

• Retraction is the reverse

Special movements

• Opposition

  • Special movement of thumb

  • Produces pad to pad contact with palm or any other finger

  • Reverse is called reposition

Special movements

• Depression and elevation

  • Movement of part of body inferiorly or superiorly:

• Examples are chewing and shrugging

Classification of Synovial Joints by range of motion

• Plane joints

• Hinge joints

• Pivot joints

• Condylar joints

• Saddle joints

• Ball and socket joints

Plane Joints (planar or gliding joints)

• Flattened or slightly curved facets

• Very Slight gliding movement

• Nonaxial (glides only in one direction)

• Multiaxial (glides in all directions)

• Carpal/carpal –

  Tarsal/tarsal –

  Vertebrae/vertebrae

  – Clavicle/sternum

Hinge Joints

• Permit angular movement in a single plane

• Elbow and knee are good examples

• Monoaxial flexion and extension

Pivot Joints

• Permit rotation in one plane

• Monoaxial

Condylar Joints (ellipsoidal joint)

• An oval articular face rests within a depression in the opposite surface

• Therefore rotation occurs in two planes--biaxial

• Radius/carpals – Phalanges/metacarpals – Phalanges/metatarsals

Saddle Joints

• Joint surfaces have concave and convex faces

• Resemble saddle

• Pollex/metacarpal is a good example

• Biaxial

Ball and Socket joints

• Round head of one bone rests in cup shaped socket of another

• Allows triaxial (many directions) movement

• Shoulder and hip joints

Bursa

bursa is a sac filled with lubricating fluid, located between tissues such as bone, muscle, tendons, and skin, that decreases rubbing, friction, and irritation

Labrum

The labrum is a piece of fibrocartilage (rubbery tissue) attached to the rim of the shoulder socket

that helps keep the ball of the joint in place. When this cartilage is torn, it is called a labral

tear. Labral tears may result from injury, or sometimes as part of the aging process

Knee joint

• Tibial collateral ligament

  • Formerly called the medial collateral

• Fibular collateral ligament

  • Formerly called the lateral collateral

• Patellar ligament

• Patellar retinaculum

• Popliteal ligament

• Anterior cruciate ligament (ACL)

• Posterior cruciate ligament (PCL)

Knee joint

• Tibial collateral ligament

  • Connects the medial epicondyle of the femur to the tibia

• Fibular collateral ligament

  • Connects the lateral epicondyle of the femur to the fibula

• Patellar ligament

  • Connects the tibial tuberosity to the patella

  • This is an extension of the rectus femoris tendon

Representative Articulations

• Patellar retinaculum

  • Connects the medial and lateral edge of the patella to the tibia

  • (Retinaculum is a band around tendons that holds them in place. It is not part of any muscle. Its function is mostly to stabilize a tendon.)

Knee joint

• Popliteal ligament

  • Connects the femur to the head of the tibia and the head of the fibula

• Anterior cruciate ligament (ACL)

  • Connects the tibia to the lateral edge of the intercondylar fossa of the femur

• Posterior cruciate ligament (PCL)

  • Connects the tibia to the medial edge of the intercondylar fossa of the femur

Ankle joint

• Deltoid ligament

  • Connects the tibia to the navicular, calcaneus, and the talus on the medial side

• Lateral ligaments

• Calcaneofibular: connects the fibula to the calcaneus

• Anterior talofibular: connects the fibula to the anterior edge of the talus

• Posterior talofibular: connects the fibula to the posterior edge of the talus

Range of motion

ROM is the extent of movement that a joint is normally capable of

Hand Movements (ROM)

• ROM in wrist includes flexion, extension, radial & ulner deviation

• ROM in hands include abduction, adduction, flexion, extension, opposition and

• circumduction of the thumb

Hip ROM

• Hip ROM includes flexion, extension and lateral & external rotation

• Adduction & Abduction

Aging and Articulations

• As we age, joints are subjected to wear and tear

• Rheumatism

  • Pain and stiffness affecting the skeletal system, muscular system, or both

• Arthritis

  • Includes all rheumatic diseases that affect synovial joints

• Damage to the articular cartilage