ArticulationsThe “Moving” Part of Anatomy!

Introduction

• Many major sports, activities and hobbies require us to be able to move around• These movements define us as

human because we have a unique ability to move in the animal kingdom• There is almost no parallel of

fine and large movement in the animal kingdom

https://www.youtube.com/watch?v=wNG0QJw7-4A

Introduction

• However movement does come at a cost• It means that things that protect

and are stiff and rigid will have to be able to bend• Since there are transitions

between areas that are designed for support and areas that are designed for movement, weaknesses can occur

https://www.youtube.com/watch?v=r_wPOfTGegA

Introduction

• While the previous slide incorporated several different major impacts, small impacts can damage parts of the body• Articulations, also known as

joints, can be damaged from relatively small impacts or repeated motions• This often presents as stubbed

fingers, sprained ankles and swollen joints https://www.youtube.com/watch?v=lgNttdd7UIc

Types of Articulations

• There are two different categories of joints• The first category of joint defines

it based on how much the joint moves• Once that has been determined,

the second category further defines the joint based on the features that make it up

Types of Articulations

• There are three different types of joints that are based on their movement• A synarthrosis is an immovable joint

• Stays There

• An amphiarthrosis is a slightly moveable joint• Almost There

• A diarthrosis is a freely moveable joint• Defiantly There

Types of Articulations

• Once you figure out what type of joint it is, you have to figure out what type of material the joint is made of• A bony joint has the ability to connect

two bones without anything in-between• A fibrous joint has no joint cavity and

are connected by fibrous connective tissue• A cartilaginous joint is connected

entirely by cartilage• A synovial joint has synovial fluid

surrounding the joint

Types of Movement

• Articulations provide the ability to move many different ways

• The movement can happen in several different ways

• Gliding movement is movement from the base of the articulation• This is good but it does not happen often in

the body

• Angular movement is when the angle created from the base of a joint changes

• Rotation happens with the angle of the base stays the same, but the position of the appendage changes

Types of Movement

• Try this…• Put your pencil or pen tip on the

center of the cross in your notes labeled gliding movement• Use your massive brain power to

create a scenario where you create gliding movement• If you are having trouble with

this, think about moving from the base

Types of Movement

• Ok smarty-pants…• Now put your pencil tip on the

cross labeled as angular movements• Now try to make an angular

movement• Hint: This is movement from the

changes the angles of the base

Types of Movement

• Last one…• Put your pencil at the center of

the cross labeled rotation• Make the pencil rotate• … But don’t change the base

angle

Synovial Joints

• Synovial joints are diarthoses (defiantly there) that are surrounded by a joint capsule• A joint capsule is a double

layered sack that contains synovial fluid• The joint capsule functions as a

protection, nutrient distribution medium and a shock absorber for the joint

Synovial Joints

• Synovial joints do not have bones that touch• The bones are capped in

articular cartilages that protect the bones from rubbing on each other• The cartilages never actually

touch because there is always a thin film of synovial fluids that separate them

Synovial Joint Accessory Structures

• Many synovial joints have accessory structures that are used to aid function within the joint and protect it from harm• A meniscus is a crescent shaped

pad of fibrocartilage located between bones• Menisci allow for better flow of

synovial fluid, divide the joint cavity or allow for variations in the shapes of surfaces

Synovial Joint Accessory Structures

• Fat pads are localized masses of adipose tissue covered by synovial membrane• They commonly surround the

joint • Because a joint can move, it often

has different shapes to it’s cavities• These pads fill the spaces that are

created when the joint moves

Ligaments

• Inside of or outside of the joint capsules ligaments support, strengthen and reinforce synovial joints• Ligaments connect bones to

different bones• These ligaments are very

important to maintaining the structure of the synovial joint

Ligaments

• Ligaments are dense regular connective tissue• This means that they are very

strong in one direction because all of their fibers run in one direction• This is why ligaments are often

found in groups• They cover the stresses from

many different angles is synovial joints

Ligaments

• While ligaments are strong, they are not invincible• A sprain is a situation where a

ligament is stretched to the point where some collagen fibers are torn but the ligament is still intact• A torn ligament is where the

ligament separates from itself or the bone completely

Video

• A full ACL reconstruction surgery • Take a moment to think do I

want to watch someone have ACL reconstruction surgery• If you do not want to see

incisions and bone drilling please do not watch the video

• https://www.youtube.com/watch?v=M-FQGMPfGac

Tendons

• Tendons connect muscles to bones (or other structures like the eye)• While they are not part of the

articulation, they often times are responsible for the force and range of motion within the articulation

Tendons

• Just as an example the tendons in the rotator cuff provide much of the support for the shoulder joint• The movements of this

diarthrosis (defiantly there) are limited by the arrangements of the tendons• Try this out by stretching your

arms!

Bursae

• Bursae are small fluid filled pockets of connective tissue• These are found connected to

and around synovial joint cavities• These bursae are lined by

synovial membrane tissue • Each one contains synovial fluid

Bursae

• These bursae are generally designed to keep tendons and ligaments from rubbing on other tissues• They serve as a buffer that helps

protect the ligaments and tendons from damage• This makes their job vital in a

synovial joint

Bursae

• Bursae can be broken due to stress or damage to the synovial joint• Generally it leads to a large

amount of swelling as the synovial fluid leaks out• Also they can develop in non

synovial joint tissues if there is an excessive amount of rubbing or pressure

Synovial Movement

• Synovial Joints can move in very interesting ways• These joints can make a wide

variety of complex movements that make up the movements of the body• Since synovial joints vary greatly,

there are many different types of movements that can be performed

Synovial Movement

• The first basic type of movement is flexion and extension• Flexion is the movement where

articulating bones decrease their angle• Extension is the movement where

articulating bones increase their angle• Hyperextension is movement past

standard anatomical position• This can be seen in the elbow and

neck

Synovial Movement

• However not all movement is regulated to linear movements• Abduction is movement away

from the center line of the body• Adduction is movement towards

the center line of the body• These movements can be seen

in the hand

Synovial Movements

• Sometimes there is a mixture between angular movement and rotational movement• Circumduction is the term given

when a limb moves in a circular direction• This would be similar to drawing

a big circle on the whiteboard without moving the wrist or elbow

Synovial Movements

• Rotational movements are often seen in the body • If the head rotates to the left or

right side of the body it is a right rotation or left rotation• If a limb rotates to the outside of

the body we call it a lateral rotation• If a limb rotates to the inside of

the body we call it a medial rotation

Synovial Movements

• The rotation between radius and ulna are a special case• During pronation the radius

moves across the surface of the ulna and the hand moves opposite of anatomical position• During supination the radius

moves back across the ulna and the hand moves to anatomical position