Joints & Movement

Joints

Joints

Functional junctions between bones that are formed wherever two or more bones meet

Synarthrotic

Immovable

Amphiarthrotic

Slightly movable

Diarthrotic

Freely movable

Fibrous Joints

• Dense connective tissue connect bones

• Between bones in close contact

• Not much movement

Kinds of Fibrous Joints

Syndesmosis, suture, gomphosis

Syndesmosis

• Joint bound by ligaments

• Permits a slight movement

• Amphiarthrotic joint

• ex. Distal end of tibia and fibula

Sutures

• Between flat bones of skull

  • ex. squamous, coronal, sagittal, and lambdoidal.

• As adult, sutures close and interlock

• synarthrotic joint (immovable)

• Fontanels - membranous areas in baby skull - allows skull to change shape during childbirth.

Gomphosis

• Cone shaped bone in a bony socket

• ex. root of tooth in jawbone

• Ligament wraps around root to hold it in

• synarthrotic joint (immovable)

Kinds of Cartilaginous Joints

• Synchondrosis - usually disappears

• Symphysis - holds two bones together with cartilage

Synchondrosis

• Bands of hyaline cartilage unit bonds

• Disappear as we grow

• ex. epiphyseal disk

• synarthrotic joint (immovable)

Symphysis

• Bones covered by a thin layer of hyaline cartilage with fibrocartilage in between

• ex. symphysis pubis and intervertebral discs

• amphiarthrotic joints (semi-movable)

Synovial Joints

• Most joints are of this type

• Freely movable joints

• Have articular cartilage, joint capsule, and synovial membrane

• diarthrotic (movable)

Ball and Socket

Movement in all planes

Condyloid

Ellipsoidal

No rotational movement

Metacarpals and phalanges

Gliding

Flat or slightly curved

Sliding motion

Between carpal and tarsal bones

Hinge

Concave surface fits into a convex surface

One plane movement

Knee, elbow, and phalanges

Pivot

One bone rotates around another

Rotational movement

Proximal end of radius and ulna, atlas and dens

Saddle

Have convex and concave surfaces

Variety of movements

Between carpal and metacarpal

Articular Cartilage

• Covers ends of bones

• Made up of hyaline cartilage

• Reduces friction and resists wear

Joint Capsule

Outer layer - fibrous connective tissue

Inner layer - synovial membrane

Outer Layer - Fibrous connective tissue

Connects to periosteum

Totally encloses the joint

Inner Layer - Synovial membrane

Shiny, vascular tissue

Secretes synovial tissue - lubricates joint and cuts down on friction

Menisci

• 1/2 moon shaped fibrocartilage

• found in some joints

• cushions the joint

Bursae

• fluid-filled sacs in joint

• found in some joints

• contain synovial fluid

• cushion and helps the movement of tendons

Flexion

• Decreasing an angle between two bones.

  1. Bending the arm at the elbow toward the shoulder.

  2. Bending your finger.

Extension

• Increasing the angle between two bones.

  1. Straightening a bone.

  2. Ex. Straightening the arm or leg.

Hyperextension

• Extension of a bone beyond normal anatomical position.

  1. Bending the head backwards as if looking up to the sky.

Dorsiflexion

• Flexing the foot at the ankle.

  1. Bending the toes up to the shin.

Plantar Flexion

• Extending the foot at the ankle.

  1. Pointing the toes.

  2. This is actually a type of extension not flexion.

Abduction

• Moving a part away from the midline of the body.

  1. Lifting leg out to side.

  2. Ex. Lifting arms lateral to shoulder.

Adduction

• Moving a part toward the midline of the body.

  1. Bringing arm back down to side.

  2. Bringing leg back down to standing.

Rotation

• Moving a part around an axis.

  1. Turning the head from side to side.

  2. Turning the palm of hand up and down.

Circumduction

• 1. Moving a part so that its end follows a circular path.

  2. Ex. Moving finger in a circle without moving the hand.

Supination

• Turning the palm of the hand upward.

Pronation

• Turning the palm of the hand downward.

Eversion

• Turning the sole of the foot outward or laterally.

Inversion

• Turning the sole of the foot inward.

Protraction

• Moving a part forward.

  1. Jutting the jaw forward.

Retraction

• Moving a part backward.

  1. Pulling the jaw back in.

Elevation

• Raising a part.

  1. Shrugging of the shoulders.

Depression

• Lowering a part.

  1. Drooping the shoulders.

Opposition

• Movement of the thumb to the finger for the purposes of grasping.