Arthrology Lincoln

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Arthrology

Chapter 9


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Arthrology Is

Study of joints

Joints are defined as places where

the rigid elements of the skeletonmeet.

HOWEVER, joints can be betweenthe soft parts of the skeleton.


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Classification of Joints

2 Methods of Classification

Functional Classification

*focuses on the amount ofmovement

allowed.

Structural Classification*focuses on the material that binds

the joint together.


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ARTHROLOGY

Types of Joints

1. SYNOSTOSIS

- called a synarthrosis or

syndesmosis- is a bone to bone union

- begins as a joint where there is afibrous membrane between the two

bones. They are sometimes calledFIBROUS JOINTS or LIGAMENTOUSUNIONS.

- These are NON-MOVEABLE

- Fontanelles are examples


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2. AMPHIARTHROSIS (cartilagenousjoints)

- moveable and immoveable- cartilage between two bones

- these joints allow somemovement while still providingprotection.


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3. DIARTHROSIS (synovial joints)

- allow for free movement

- have three characteristics:

1. synovial membrane- a serous membrane that

produces synovial fluid which reducesfriction and absorbs shock.

2. articular cartilage3. capsule

-dense connective tissuecovering the joint


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Summary of Joint Classes

Structural Class Characteristics Types Mobility

Fibrous Bones united by

collagen fibers

1. Suture

2. Syndesmosis

3. gomphosis

1. Immobile

(synarthrosis)

2. Slightly moveable

(amphiarthrosis)

3. Immobile

Cartilaginous Bone ends united by

cartilage

1. Synchondrosis

(hyaline)

2. Symphysis

(fibrocartliage)

1. Immobile

2. Slightly moveable

Synovial Bone ends covered with

articular cartilage and

enclosed within a

capsule lined with a

synovial membrane

1. Plane

2. Hinge

3. Pivot

4. Condyloid

5. Saddle

6. Ball and socket

Freely moveable

(diarthrosis) which depends

on joint design


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The synovial fluid helps reducefriction, disipate heat, and absorbshock.

The articular cartilage acts similarly toteflon, which helps reduce friction

and pressure.

The joint capsule covers and protects

the synovial membrane.


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There are several ligaments that helphold the portions of the jointtogether.

Intracapuslar Ligament hold thebones together. Not found in every

joint.Extracapsular Ligament called the

collateral ligament. It is a singleband that is actually a thickening ofthe joint capsule.


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The synovial membrane is 3-dimensional, like aknee support enclosing the entire joint. It is NOTfound between the bones. It produces thesynovial fluid.

BURSAE are found between the muscle andtendons and the bone/joint. These are fluid filledsacs that reduce friction. In some cases they areextensions of the synovial sac. When theybecome tubular, they can envelope the tendonsand become a SYNOVIAL SHEATH. When thesebursa become dry, friction and inflammationresult, causing BURSITIS.


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We can increase the surface area ofa joint by having a MENISCUS. Theknee has this sort of anatomy.

This type of cartilage can be torn bytorque. Meniscal cartilage cannotheal itself.


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How Do Muscles Act on Bones?

Flexion vs. Extension

Dorsiflexion vs. Plantarflexion

Abduction vs. Adduction

CircumductionRotation

Pronation vs. Supination

Protraction vs. Retraction

Elevation vs. Depression

Inversion vs. Eversion


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Types of Joints (Articulations)

1. Ball and Socket Joint

- allow for the most freedom of movement

- triaxial movement flexion, extension,abduction, adduction, circumflexion, and

rotation2. Hinge Joint

- uniaxial allows movement in only onedirection. Back and Forth

- allows only flexion and extension in oneplane (sagittal)

- many times the articular surfaces will havea distinct shape (ie: spool shaped trochlearsurface of the humerus)


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3. Pivot Joint

- allows rotation (uniaxial)

- rounded, pointed, or conical surface on onebone that fits into a ring of bone on another.

4. Saddle Joint

- biaxial

- allows flexion, extension, abduction,adduction, and circumduction.

- surfaces are inverted relative to each other.


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5. Condyloid Joint

- biaxial

- one bone is concave(hollowed out depression) and theother is convex (rounded orelliptical).

- allows flexion, extension,abduction, and adduction.

- NO ROTATION


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6. Sliding or Gliding Joint

- biaxial

- side to side, back and forth

- two flat surfaces that slide over each other

- NO ANGULAR MOTION

7. Tongue and Groove (Mortise and Tenon)

- uniaxial

- one side is a slot, the other side is an

extension that fits into the slot.- NO SIDE TO SIDE MOVEMENT

- Allows flexion and extension


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Introduction to Myology and Movement

Human motion and walking is dueto a system of levers that are madefrom bones and muscles.

A lever has a fulcrum, or pivotpoint; a force, or energy that hasto be applied; and a resistance, or

opposition to movement. A wheel is a lever with the pivot in

the center.


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3 Types of Human Levers Systems

Class 1: Fulcrum is between theforce and load.

load

Force

fulcrum

This type of lever pulls our head into an extended position once flexed.


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Class 2: The load is between theforce and fulcrum.

The muscles that elevate us to our tip toesplantarflexion of the foot on the leg.


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Class 3 Lever

The load is opposite the fulcrum.

Examples of this type of

lever are muscles that movethe forearm.


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Requirements For Movement

1. An alive muscle

2. A stimulus

- nerve impulse

3. At least 2 bones- diarthrosis

- the joint must allow for movement inplane that the muscle shortens.

- the muscle must be able to pull theload

- force must be greater than theresistance


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Muscles that stabilize a limb so it canmove is a FIXATOR.

For example, the trapezius stabilizes the

clavicle and scapula so we can move thearm but not have the head of thehumerus become deflected in anydirection.

A muscle that provides most of the forcefor a particular movement is the PRIMEMOVER. For example, the deltoid is theprime flexor of the arm on the shoulder.


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Muscle pairs must work together:

AGONIST assists movementANTAGONIST resists movement

For example: The triceps surae (gastrocnemius andsoleus complex) plantarflexes the foot on the leg.This is the plantarflexory agonist. The musclesthat work against the triceps are the dorsiflexorymuscles (tibialis anterior and long extensors).

The opposite is also true: The plantarflexors are theantagonists to the dorsiflexors.


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SYNOVIAL JOINTS

Occurs at ends of bones Articular cartilage enclosed within an

articular capsule and lined with a synovialmembrane.

All freely moveable (diarthrosis) Type of movement depends on the shape

and design of the joint. 6 Types

1. Plane 4. Condyloid2. Hinge 5. Saddle3. Pivot 6. Ball and Socket


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Part of a Synovial Joint

Joint Cavity fluid filled potential space. Articulating surfaces:

simple joint 2 articulating surfacescompound joint - >2 articular surfaces

Articular Cartilage hyaline cartilage. Spongycushions absorb compression

Articular Capsule2 layers:

1. fibrous capsule outside, dense irregular

CT that is continuous with the periosteum.2. synovial membrane loose CT. Makessynovial fluid for protection.


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Synovial Fluid*viscous fluid resembling raw egg whites.*filtrate of blood*contains glycoproteins

Reinforcing Ligaments*bands that hold the joint together.*Extracapsular outside the capsule*Intracapsular internal to the capsule

Neurovascular Bundle

*Nerves and Blood Vessels*Detect pain when joint is disrupted (ie:

sprains,dislocations)


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Synovial joints have lubricating devices toallow the bones to move across oneanother with minimal friction.

Synovial joints are subject to

compression. Compression occurs whenmuscles that hold the bones togethercontract.

Lubricating fluid is squeezed out of thejoint onto the opposing surfaces. When

pressure on the joint ceases, the fluidrushes back into the articular cartilage.The fluid is absorbed back into thecartilage ready for the next compressiveforce. This is called weeping lubrication.


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MOVEMENTS OF

SYNOVIAL JOINTS

Movement caused by muscularcontraction.

3 Types of Movments:

1. Gliding sliding of flat surfacesacross each other. Found mainly betweenthe carpals and between the tarsals.

2. Angular increase or decreases the

angle between the two bones

3. Rotation movement of bonearound its long axis.


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SYNOVIAL JOINTS ARE CLASSIFIED

BY SHAPE

The shapes of the articulating surfaces determinethe movement allowed at a joint.

Types of synovial joints:

1. plane flat articular surfaces. Short gliding

movements are allowed.2. hinge cylindrical end of one bone fits into

the trough of another bone. Angular movement isin one plane. Uniaxial joint along one plane.

3. pivot rounded end of one fits into a ring

formed by another bone.


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4. Condyloid egg shaped articularsurface fits into the oval concavityin another.

5. Saddle Joint has both convexand concave areas.

6. Ball and Socket spherical head

of one bone fits into a round socketin another.


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Disorders of Joints

Injury

1. Sprain

- stretching or tearing of aligament

2. Dislocation

- joint alignment is interrupted- Subluxationis a partial or

incomplete dislocation of a

joint.


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Inflammatory Conditions

1. Bursitis

- inflammation of a bursa

- Bursae are sacs of fluid thatserve to

protect boney prominences.2. Tendinitis

- inflammation of a tendonsheath


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3. Osteoarthritis- most common type of arthritis- degenerative condition of the

articular cartilage- Enzymes wear down the cartilagematrix due to wear and tear

4. Rheumatoid Arthritis- inflammation of the synovium- autoimmune in origin- often results in ankylosis of the

joint

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