Joints - Des Moines Area Community College Boone...Figure 8.5d Movements allowed by synovial joints....

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PowerPoint® Lecture Slides

prepared by

Karen Dunbar Kareiva

Ivy Tech Community College© Annie Leibovitz/Contact Press Images

Chapter 8 Part A

Joints

© 2016 Pearson Education, Inc.

Video: Why This Matters


8.1 Classification of Joints

• Joints, also called articulations: sites where

two or more bones meet

• Functions of joints: give skeleton mobility and

hold skeleton together

• Two classifications:

1. Structural: three types based on what material

binds the joints and whether a cavity is present

• Fibrous

• Cartilaginous

• Synovial


8.1 Classification of Joints

2. Functional classifications: three types based on

movement joint allows

• Synarthroses: immovable joints

• Amphiarthroses: slightly movable joints

• Diarthroses: freely movable joints

• Structural classifications are more clear cut, so

these will be used here


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8.2 Fibrous Joints

• Bones joined by dense fibrous connective tissue

• No joint cavity

• Most are immovable

– Depends on length of connective tissue fibers

• Three types of fibrous joints

– Sutures

– Syndesmoses

– Gomphoses


Sutures

• Rigid, interlocking joints of skull

• Allow for growth during youth

– Contain short connective tissue fibers that allow

for expansion

• In middle age, sutures ossify and fuse

– Immovable joints join skull into one unit that

protects brain

– Closed, immovable sutures referred to as

synostoses


Figure 8.1a Fibrous joints.

Suture

Joint held together with very short,

interconnecting fibers, and bone

edges interlock. Found only in

the skull.

Suture

line

Fibrous

connective

tissue© 2016 Pearson Education, Inc.

Syndesmoses

• Bones connected by ligaments, bands of fibrous

tissue

• Fiber length varies, so movement varies

– Short fibers offer little to no movement

• Example: inferior tibiofibular joint

– Longer fibers offer a larger amount of movement

• Example: interosseous membrane connecting radius

and ulna


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Figure 8.1b Fibrous joints.

Syndesmosis

Joint held together by a ligament.

Fibrous tissue can vary in length,

but is longer than in sutures.

Fibula

Tibia

Ligament


Gomphoses

• Peg-in-socket joints

• Only examples are the teeth in alveolar sockets

• Fibrous connection is the periodontal ligament

– Holds tooth in socket


Figure 8.1c Fibrous joints.

Gomphosis

“Peg in socket” fibrous joint.

Periodontal ligament holds tooth

in socket.

Socket of

alveolar

process

Root of

tooth

Periodontal

ligament


8.3 Cartilaginous Joints

• Bones united by cartilage

• Like fibrous joints, have no joint cavity

• Not highly movable

• Two types

– Synchondroses

– Symphyses


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Synchondroses

• Bar or plate of hyaline cartilage unites bones

• Almost all are synarthrotic (immovable)

• Examples

– Temporary epiphyseal plate joints

• Become synostoses after plate closure

– Cartilage of 1st rib with manubrium of sternum


Figure 8.2a Cartilaginous joints.

Synchondroses

Bones united by hyaline cartilage

Sternum(manubrium)

Epiphyseal

plate (temporaryhyaline cartilagejoint)

Joint between

first rib andsternum(immovable)


Symphyses

• Fibrocartilage unites bone in symphysis joint

– Hyaline cartilage also present as articular

cartilage on bony surfaces

• Symphyses are strong, amphiarthrotic (slightly

movable) joints

• Examples

– Intervertebral joints

– Pubic symphysis


Figure 8.2b Cartilaginous joints.

Symphyses

Bones united by fibrocartilage

Body of vertebra

Fibrocartilaginousintervertebral disc(sandwiched betweenhyaline cartilage)

Pubic symphysis


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8.4 Synovial Joints

• Bones separated by fluid-filled joint cavity

• All are diarthrotic (freely movable)

• Include almost all limb joints

• Characteristics of synovial joints

– Have six general features

– Have bursae and tendon sheaths associated

with them

– Stability is influenced by three factors

– Allow several types of movements

– Classified into six different types


General Structure

• Synovial joints have six general features:

1. Articular cartilage: consists of hyaline

cartilage covering ends of bones

• Prevents crushing of bone ends

2. Joint (synovial) cavity: small, fluid-filled

potential space that is unique to synovial joints

3. Articular (joint) capsule: two layers thick

• External fibrous layer: dense irregular connective

tissue

• Inner synovial membrane: loose connective tissue

that makes synovial fluid


General Structure (cont.)

4. Synovial fluid: viscous, slippery filtrate of

plasma and hyaluronic acid

• Lubricates and nourishes articular cartilage

• Contains phagocytic cells to remove microbes and

debris

5. Different types of reinforcing ligaments

• Capsular: thickened part of fibrous layer

• Extracapsular: outside the capsule

• Intracapsular: deep to capsule; covered by synovial

membrane



6. Nerves and blood vessels

• Nerves detect pain; monitor joint position and stretch

• Capillary beds supply filtrate for synovial fluid


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Figure 8.3 General structure of a synovial joint.

Ligament

Joint cavity

(containssynovial fluid)

Articular (hyaline)cartilage

Fibrous

layer

Synovialmembrane(secretessynovialfluid)

Periosteum

Articular

capsule



• Other features of some synovial joints:

– Fatty pads

• For cushioning between fibrous layer of capsule and

synovial membrane or bone

– Articular discs (menisci)

• Fibrocartilage separates articular surfaces to improve

“fit” of bone ends, stabilize joint, and reduce wear and

tear


Bursae and Tendon Sheaths

• Bags of synovial fluid that act as lubricating “ball

bearing”

– Not strictly part of synovial joints, but closely

associated

• Bursae: reduce friction where ligaments,

muscles, skin, tendons, or bones rub together

• Tendon sheaths: elongated bursae wrapped

completely around tendons subjected to friction


Figure 8.4a Bursae and tendon sheaths.

Acromionof scapula

Subacromial

bursa

Fibrous layer of

articular capsule

Joint cavitycontainingsynovial fluid

Articularcartilage

Tendon

sheath

Synovialmembrane

Tendon oflong headof bicepsbrachii muscle

Fibrouslayer

Humerus

Frontal section through the right shoulder joint


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Figure 8.4b Bursae and tendon sheaths.

Bursa rollsand lessensfriction.

Humerus headrolls mediallyas arm abducts.

Humerus moving

Enlargement of (a), showing how

a bursa eliminates friction where

a ligament (or other structure) would

rub against a bone


Factors Influencing Stability of Synovial

Joints

• Three factors determine stability of joints to

prevent dislocations:

1. Shape of articular surface (minor role)

• Shallow surfaces less stable than ball-and-socket

2. Ligament number and location (limited role)

• The more ligaments, the stronger the joint

3. Muscle tone keeps tendons taut as they cross

joints (most important)

• Extremely important in reinforcing shoulder and knee

joints and arches of the foot


Table 8.2-1 Structural and Functional Characteristics of Body Joints


Table 8.2-2 Structural and Functional Characteristics of Body Joints (continued)


8





Movements Allowed by Synovial Joints

• All muscles attach to bone or connective tissue

at no fewer than two points

– Origin: attachment to immovable bone

– Insertion: attachment to movable bone

• Muscle contraction causes insertion to move

toward origin

• Movements occur along transverse, frontal, or

sagittal planes



(cont.)

• Range of motion allowed by synovial joints

– Nonaxial: slipping movements only

– Uniaxial: movement in one plane

– Biaxial: movement in two planes

– Multiaxial: movement in or around all three

planes

• Three general types of movements

– Gliding

– Angular movements

– Rotation


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(cont.)

• Gliding movements

– One flat bone surface glides or slips over

another similar surface

– Examples

• Intercarpal joints

• Intertarsal joints

• Between articular processes of vertebrae


Figure 8.5a Movements allowed by synovial joints.

Gliding

Gliding movements at the wrist



(cont.)

• Angular movements

– Increase or decrease angle between two bones

– Movement along sagittal plane

– Angular movements include:

• Flexion: decreases the angle of the joint

• Extension: increases the angle of the joint

– Hyperextension: movement beyond the anatomical

position


Figure 8.5b Movements allowed by synovial joints.

HyperextensionExtension

Flexion

Angular movements: flexion,

extension, and hyperextension

of the neck


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Figure 8.5c Movements allowed by synovial joints.

Extension

Hyperextension Flexion

Angular movements: flexion,

extension, and hyperextension of

the vertebral column© 2016 Pearson Education, Inc.

Figure 8.5d Movements allowed by synovial joints.

FlexionHyper-

extension

Extension

Flexion

Extension

Angular movements: flexion, extension, and hyperextension at the shoulder and knee



(cont.)

• Angular movements (cont.)

– Abduction: movement along frontal plane, away

from the midline

– Adduction: movement along frontal plane,

toward the midline

– Circumduction

• Involves flexion, abduction, extension, and adduction

of limb

• Limb describes cone in space


Figure 8.5e Movements allowed by synovial joints.

Abduction

Adduction Circumduction

Angular movements: abduction, adduction, and

circumduction of the upper limb at the shoulder


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(cont.)

• Rotation: turning of bone around its own long

axis, toward midline or away from it

– Medial: rotation toward midline

– Lateral: rotation away from midline

– Examples

• Rotation between C1 and C2 vertebrae

• Rotation of humerus and femur


Figure 8.5f Movements allowed by synovial joints.

Rotation

Lateralrotation

Medialrotation

Rotation of the head, neck, and lower limb



(cont.)

• Special movements

– Supination and pronation: rotation of radius

and ulna

• Supination: palms face anteriorly

– Radius and ulna are parallel

• Pronation: palms face posteriorly

– Radius rotates over ulna

– Dorsiflexion and plantar flexion of foot

• Dorsiflexion: bending foot toward shin

• Plantar flexion: pointing toes


Figure 8.6a Special body movements.

Pronation(radius rotatesover ulna)

Supination(radius and ulnaare parallel)

P

S

Pronation (P) and supination (S)


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Figure 8.6b Special body movements.

Dorsiflexion

Plantar flexion

Dorsiflexion and plantar flexion



(cont.)

• Special movements (cont.)

– Inversion and eversion of foot

• Inversion: sole of foot faces medially

• Eversion: sole of foot faces laterally

– Protraction and retraction: movement in lateral

plane

• Protraction: mandible juts out

• Retraction: mandible is pulled toward neck


Figure 8.6c Special body movements.

Inversion

Eversion

Inversion and eversion


Figure 8.6d Special body movements.

Protractionof mandible

Retractionof mandible

Protraction and retraction


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(cont.)

• Special movements (cont.)

– Elevation and depression of mandible

• Elevation: lifting body part superiorly

– Example: shrugging shoulders

• Depression: lowering body part

– Example: opening jaw

– Opposition: movement of thumb

• Example: touching thumb to tips of other fingers on

same hand or any grasping movement


Figure 8.6e Special body movements.

Elevation and depression


Figure 8.6f Special body movements.

Opposition

Opposition


Types of Synovial Joints

• There are six different types of synovial joints

– Categories are based on shape of articular

surface, as well as movement joint is capable of

• Plane

• Hinge

• Pivot

• Condylar

• Saddle

• Ball-and-socket


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Focus Figure 8.1a Six types of synovial joint shapes determine the movements that can occur at a joint.

Plane joint Nonaxial movement

Meta-carpals

Carpals

Flatarticularsurfaces

Gliding

Examples: Intercarpal joints, intertarsal joints, joints betweenvertebral articular surfaces


Focus Figure 8.1b Six types of synovial joint shapes determine the movements that can occur at a joint.

Hinge joint

Humerus

Cylinder

Trough

Uniaxial movement

Medial/lateralaxis

Ulna Flexion and extension

Examples: Elbow joints, interphalangeal joints


Focus Figure 8.1c Six types of synovial joint shapes determine the movements that can occur at a joint.

Pivot joint Uniaxial movement

Sleeve(bone andligament)

Vertical axis

Ulna

Radius

Axle (roundedbone)

Rotation

Examples: Proximal radioulnar joints, atlantoaxial joint


Focus Figure 8.1d Six types of synovial joint shapes determine the movements that can occur at a joint.

Condylar joint

Phalanges Medial/lateralaxis

Ovalarticularsurfaces

Biaxial movement

Anterior/posterioraxis

Meta-carpals

Flexion

and extension

Adduction

and abduction

Examples: Metacarpophalangeal (knuckle) joints, wrist joints


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Focus Figure 8.1e Six types of synovial joint shapes determine the movements that can occur at a joint.

Saddle joint


MetacarpalI

Articularsurfacesare bothconcaveand convex

Biaxial movement

Medial/lateralaxis

Adduction

and abduction

Flexion and

extension

TrapeziumExample: Carpometacarpal joints of the thumbs


Focus Figure 8.1f Six types of synovial joint shapes determine the movements that can occur at a joint.

Ball-and-socket joint Multiaxial movement


Cup(socket)

Medial/lateralaxis

Scapula

Sphericalhead(ball)

Humerus Flexion

and extension

Adduction and

abductionRotation

Examples: Shoulder joints and hip joints

Verticalaxis


8.5 Selected Synovial Joints

• Synovial joints are diverse

• All have general features, but some also have unique structural features, abilities, and weaknesses

• Five main synovial joints• Knee

• Shoulder

• Elbow

• Hip

• Jaw


Knee Joint

• Largest, most complex joint of body

• Consists of three joints surrounded by single cavity

1. Femoropatellar joint• Plane joint

• Allows gliding motion during knee flexion

2. Lateral joint and 3. Medial joint• Lateral and medial joints together are called tibiofemoral

joint

• Joint between femoral condyles and lateral and medial menisci of tibia

• Hinge joint that allows flexion, extension, and some rotation when knee partly flexed


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Figure 8.7a The knee joint.

Femur

Articularcapsule

Posterior

cruciate

ligament

Lateral meniscus

Anterior

cruciate

ligament

Tibia

Tendon ofquadricepsfemoris

Suprapatellarbursa

Patella

Subcutaneous

prepatellar bursa

Synovial cavity

Lateral meniscus

Infrapatellar fat pad

Deep infrapatellarbursa

Patellar ligament

Sagittal section through the right knee joint


Figure 8.7b The knee joint.

Anterior

Anterior

cruciate

ligament

Articularcartilageon medialtibialcondyle

Medial

meniscus

Posterior

cruciate ligament

Superior view of the right tibia in the knee joint,

showing the menisci and cruciate ligaments

Articularcartilage onlateral tibialcondyle

Lateral

meniscus


A&P Flix™: Knee


Knee Joint (cont.)

• Joint capsule is thin and absent anteriorly

• Anteriorly, quadriceps tendon gives rise to three broad ligaments that run from patella to tibia

• Medial and lateral patellar retinacula that flank the patellar ligament

• Doctors tap patellar ligament to test knee-jerk reflex

• At least 12 bursae associated with knee joint


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Figure 8.7c The knee joint.

Quadricepsfemoris muscle

Tendon ofquadricepsfemoris muscle

Patella

Lateral

patellar

retinaculum

Fibular

collateral

ligament

Fibula

Medial patellar

retinaculum

Tibial collateral

ligament

Patellar

ligament

Tibia

Anterior view of right knee


Knee Joint (cont.)

• Capsular, extracapsular, or intracapsular ligaments act to stabilize knee joint

• Capsular and extracapsular ligaments help prevent hyperextension of knee

• Fibular and tibial collateral ligaments: prevent rotation when knee is extended

• Oblique popliteal ligament: stabilizes posterior knee joint

• Arcuate popliteal ligament: reinforces joint capsule posteriorly


Figure 8.7d The knee joint.

Tendon ofadductormagnus

Medial head ofgastrocnemiusmuscle

Popliteusmuscle (cut)

Tibial

collateral

ligament

Tendon ofsemimembranosusmuscle

Femur

Articular capsule

Oblique popliteal

ligament

Lateral head ofgastrocnemiusmuscle

Bursa

Fibular collateral

ligament

Arcuate popliteal

ligament

Tibia

Posterior view of the joint capsule, including ligaments


Knee Joint (cont.)

• Intracapsular ligaments reside within capsule, but outside synovial cavity

• Help to prevent anterior-posterior displacement• Anterior cruciate ligament (ACL)

• Attaches to anterior tibia

• Prevents forward sliding of tibia and stops hyperextension of knee

• Posterior cruciate ligament• Attaches to posterior tibia

• Prevents backward sliding of tibia and forward sliding of femur


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Figure 8.7e The knee joint.

Posterior

cruciate

ligament

Fibular

collateral

ligament

Medial

condyle

Tibial

collateral

ligament

Anterior

cruciate

ligament

Medialmeniscus

Patellarligament

Patella

Quadricepstendon

Lateralcondyleof femur

Lateralmeniscus

Tibia

Fibula

Anterior view of flexed knee, showing the

cruciate ligaments (articular capsule

removed, and quadriceps tendon cut and

reflected distally)


A&P Flix™: Rotating Knee


Figure 8.7f The knee joint.

Medial femoral

condyle

Anterior cruciate

ligament

Medial meniscus

on medial tibial

condyle

Patella

Photograph of an opened knee joint;

view similar to (e)


Clinical – Homeostatic Imbalance 8.1

• Knee absorbs great amount of vertical force; however, it is vulnerable to horizontal blows

• Common knee injuries involved the 3 C’s:• Collateral ligaments

• Cruciate ligaments

• Cartilages (menisci)

• Lateral blows to extended knee can result in tears in tibial collateral ligament, medial meniscus, and anterior cruciate ligament

• Injuries affecting just ACL are common in runners who change direction, twisting ACL

• Surgery usually needed for repairs


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Figure 8.8 The “unhappy triad:” ruptured ACL, ruptured tibial collateral ligament, and torn meniscus.

Lateral

Hockey puckPatella

(outline)

Medial

Tibial

collateral

ligament

(torn)

Medial

meniscus

(torn)

Anterior

cruciate

ligament

(torn)


Shoulder (Glenohumeral) Joint

• Most freely moving joint in body

• Stability is sacrificed for freedom of movement

• Ball-and-socket joint• Large, hemispherical head of humerus fits in small,

shallow glenoid cavity of scapula• Like a golf ball on a tee

• Articular capsule enclosing cavity is also thin and loose

• Contributes to freedom of movement


Figure 8.9a The shoulder joint.

Acromion of scapula

Coracoacromial ligament

Subacromial bursa

Fibrous layer ofarticular capsule

Tendon sheath

Tendon of long headof biceps brachii muscle

Synovial cavity ofthe glenoid cavitycontaining synovialfluid

Articular cartilage

Synovial membrane


Humerus

Frontal section through right shoulder joint


A&P Flix™: Rotating Shoulder Joint


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Figure 8.9b The shoulder joint.

Synovial cavityof the glenoidcavity containingsynovial fluid

Articular cartilage


Humerus

Cadaver photo corresponding to (a)


Shoulder (Glenohumeral) Joint (cont.)

• Glenoid labrum: fibrocartilaginous rim around glenoid cavity

• Helps to add depth to shallow cavity

• Cavity still only holds one-third of head of humerus

• Reinforcing ligaments• Primarily on anterior aspect

• Coracohumeral ligament• Helps support weight of upper limb

• Three glenohumeral ligaments• Strengthen anterior capsule, but are weak support


Figure 8.9c The shoulder joint.

Acromion


Subacromial bursa

Coracohumeral

ligament

Transverse humeralligament

Tendon sheath

Tendon of long headof biceps brachiimuscle

Coracoid process

Articular capsulereinforced byglenohumeral

ligaments

Subscapularbursa

Tendon of thesubscapularismuscle

Scapula

Anterior view of right shoulder joint capsule


Figure 8.9d The shoulder joint.

Acromion

Coracoid process

Articular capsule

Glenoid cavity

Glenoid labrum


Glenohumeral ligaments

Tendon of thesubscapularis muscle

ScapulaPosterior Anterior

Lateral view of socket of right shoulder joint,

humerus removed


21

Shoulder (Glenohumeral) Joint (cont.)

• Reinforcing muscle tendons contribute most to joint stability

• Tendon of long head of biceps brachii muscle is “superstabilizer”

• Travels through intertubercular sulcus

• Secures humerus to glenoid cavity

• Four rotator cuff tendons encircle the shoulder joint

• Subscapularis

• Supraspinatus

• Infraspinatus

• Teres minor


A&P Flix™: Rotator Cuff Muscles: Overview (a)


A&P Flix™: Rotator Cuff Muscles: Overview (b)


Figure 8.9c The shoulder joint.

Acromion


Subacromial bursa

Coracohumeral

ligament

Transverse humeralligament

Tendon sheath

Tendon of long headof biceps brachiimuscle

Coracoid process

Articular capsulereinforced byglenohumeral

ligaments

Subscapularbursa

Tendon of thesubscapularismuscle

Scapula

Anterior view of right shoulder joint capsule


22

Figure 8.9d The shoulder joint.

Acromion

Coracoid process

Articular capsule

Glenoid cavity

Glenoid labrum


Glenohumeral ligaments

Tendon of thesubscapularis muscle

ScapulaPosterior Anterior

Lateral view of socket of right shoulder joint,

humerus removed


Figure 8.9e The shoulder joint.

Acromion (cut)

Glenoid cavity

of scapula

Glenoid labrum

Rotator cuffmuscles(cut)

Capsule ofshoulder joint(opened)

Head of humerus

Posterior view of an opened right shoulder joint


A&P Flix™: Movement at Glenohumeral Joint: An Overview


A&P Flix™: Movement at GlenohumeralJoint (a)


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A&P Flix™: Movement at GlenohumeralJoint (b)


Elbow Joint

• Humerus articulates with radius and ulna

• Hinge joint formed primarily from trochlear notch of ulna articulating with trochlea of humerus

• Allows for flexion and extension only

• Anular ligament surrounds head of radius

• Two capsular ligaments restrict side-to-side movement

• Ulnar collateral ligament

• Radial collateral ligament


A&P Flix™: Movement of Elbow Joint (b)


Figure 8.10a The elbow joint.

Articularcapsule

Synovialmembrane

Humerus

Fat pad

Tendon oftriceps muscle

Bursa

Trochlea

Articular cartilageof the trochlearnotch

Median sagittal section through right elbow

(lateral view)

Synovial cavity

Articular cartilage

Coronoid process

Tendon ofbrachialis muscle

Ulna


24

Figure 8.10b The elbow joint.

Humerus

Anular

ligament

Lateralepicondyle

Articularcapsule

Radial

collateral

ligament

Olecranon

Ulna

Lateral view of right elbow joint

Radius


Figure 8.10c The elbow joint.

Humerus

Anular

ligament

Medialepicondyle

Radius

Articularcapsule

Coronoidprocessof ulna

Ulna

Ulnar

collateral

ligament

Cadaver photo of medial view of right elbow


A&P Flix™: Rotating Elbow


Figure 8.10d The elbow joint.

Articularcapsule

Anular

ligament

Coronoidprocess

Medialepicondyle

Ulnar

collateral

ligament

Humerus

Radius

Ulna

Medial view of right elbow


25

A&P Flix™: The Elbow Joint and Forearm: An Overview


Hip (Coxal) Joint

• Ball-and-socket joint

• Large, spherical head of the femur articulates with deep cup-shaped acetabulum

• Good range of motion, but limited by the deep socket

• Acetabular labrum: rim of fibrocartilage that enhances depth of socket (hip dislocations are rare)


Figure 8.11a The hip joint.

Articular

cartilage

Acetabular

labrum

Femur

Hip (coxal) bone

Ligament of the

head of the femur

(ligamentum teres)

Synovial cavity

Articular capsule

Frontal section through the right hip joint


A&P Flix™: Movement at Hip Joint: Overview


26

Figure 8.11b The hip joint.

Acetabular

labrum

Synovial

membrane

Ligament of the

head of the femur

(ligamentum teres)

Head of femur

Articular capsule

(cut)

Photo of the interior of the hip joint, lateral view


Hip (Coxal) Joint (cont.)

• Reinforcing ligaments include:• Iliofemoral ligament

• Pubofemoral ligament

• Ischiofemoral ligament

• Ligament of head of femur (ligamentum teres)• Slack during most hip movements, so not important in

stabilizing

• Does contain artery that supplies head of femur

• Greatest stability comes from deep ball-and-socket joint


Figure 8.11c The hip joint.

Ischium

Iliofemoral

ligament

Ischiofemoral

ligament

Greater

trochanter

of femur

Posterior view of right hip joint,

capsule in place


Figure 8.11d The hip joint.

Anterior

inferior iliac

spine

Greater

trochanter

Iliofemoral

ligament

Pubofemoral

ligament

Anterior view of right hip joint, capsule in place


27

A&P Flix™: Rotatable Hip


Temporomandibular Joint (TMJ)

• Jaw joint is a modified hinge joint

• Mandibular condyle articulates with temporal bone

• Posterior temporal bone forms mandibular fossa, while anterior portion forms articular tubercle

• Articular capsule thickens into strong lateralligament


Temporomandibular Joint (TMJ) (cont.)

• Two types of movement• Hinge: depression and elevation of mandible

• Gliding: side-to-side (lateral excursion) grinding of teeth

• Most easily dislocated joint in the body


Figure 8.12a The temporomandibular (jaw) joint.

Mandibular fossaArticular tubercleZygomatic process

Infratemporal fossa

Externalacousticmeatus

Articularcapsule

Ramus ofmandible

Lateralligament

Location of the joint in the skull


28

Figure 8.12b The temporomandibular (jaw) joint.

Articular disc

Mandibularfossa

Articular tubercle

Superior jointcavity

Articularcapsule

Synovialmembranes

Condylarprocess ofmandible

Ramus ofmandible

Inferior jointcavity

Enlargement of a sagittal section through the joint


Figure 8.12c The temporomandibular (jaw) joint.

Superior view

Outline ofthe mandibularfossa

Lateral excursion: lateral (side-to-side) movements of the mandible



• Dislocation of TMJ is most common because of shallow socket of joint

• Almost always dislocates anteriorly, causing mouth to remain open

• To realign, physician must push mandible back into place



• Symptoms: ear and face pain, tender muscles, popping sounds when opening mouth, joint stiffness

• Usually caused by grinding teeth, but can also be due to jaw trauma or poor occlusion of teeth

• Treatment for grinding teeth includes bite plate

• Relaxing jaw muscles helps


29

8.6 Disorders of Joints

Common Joint Injuries

• Cartilage tears

• Due to compression and shear stress

• Fragments may cause joint to lock or bind

• Cartilage rarely repairs itself

• Repaired with arthroscopic surgery

• Partial menisci removal renders joint less stable but mobile; complete removal leads to osteoarthritis

• Meniscal transplant possible in younger patients

• Perhaps meniscus grown from own stem cells in future


Figure 8.13 Arthroscopic photograph of a torn medial meniscus.

Femur

Meniscus

Tear inmeniscus

Tibia


Common Joint Injuries (cont.)

• Sprains• Reinforcing ligaments are stretched or torn

• Common sites are ankle, knee, and lumbar region of back

• Partial tears repair very slowly because of poor vascularization

• Three options if torn completely• Ends of ligaments can be sewn together

• Replaced with grafts

• Just allow time and immobilization for healing


Common Joint Injuries (cont.)

• Dislocations (luxations)• Bones forced out of alignment

• Accompanied by sprains, inflammation, and difficulty moving joint

• Caused by serious falls or contact sports

• Must be reduced to treat

• Subluxation: partial dislocation of a joint


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Inflammatory and Degenerative Conditions

• Bursitis• Inflammation of bursa, usually caused by blow or

friction

• Treated with rest and ice and, if severe, anti-inflammatory drugs

• Tendonitis• Inflammation of tendon sheaths, typically caused by

overuse

• Symptoms and treatment similar to those of bursitis


Inflammatory and Degenerative Conditions (cont.)

• Arthritis• >100 different types of inflammatory or

degenerative diseases that damage joints

• Most widespread crippling disease in the U.S.

• Symptoms: pain, stiffness, and swelling of joint

• Acute forms: caused by bacteria, treated with antibiotics

• Chronic forms: osteoarthritis, rheumatoidarthritis, and gouty arthritis



• Osteoarthritis (OA)• Most common type of arthritis

• Irreversible, degenerative (“wear-and-tear”) arthritis

• May reflect excessive release of enzymes that break down articular cartilage

• Cartilage is broken down faster than it is replaced

• Bone spurs (osteophytes) may form from thickened ends of bones

• By age 85, half of Americans develop OA, more women than men



• Osteoarthritis (OA) (cont.)• OA is usually part of normal aging process

• Joints may be stiff and make crunching noise referred to as crepitus, especially upon rising

• Treatment: moderate activity, mild pain relievers, capsaicin creams

• Glucosamine, chondroitin sulfate, and nutritional supplements not effective


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• Rheumatoid arthritis (RA)• Chronic, inflammatory, autoimmune disease of

unknown cause• Immune system attacks own cells

• Usually arises between ages 40 and 50, but may occur at any age; affects three times as many women as men

• Signs and symptoms include joint pain and swelling (usually bilateral), anemia, osteoporosis, muscle weakness, and cardiovascular problems



• Rheumatoid arthritis (RA) (cont.)• RA begins with inflammation of synovial membrane

(synovitis) of affected joint

• Inflammatory blood cells migrate to joint, release inflammatory chemicals that destroy tissues

• Synovial fluid accumulates, causing joint swelling

• Inflamed synovial membrane thickens into abnormal pannus tissue that clings to articular cartilage

• Pannus erodes cartilage, scar tissue forms and connects articulating bone ends (ankylosis)



• Rheumatoid arthritis (RA) (cont.)• Treatment includes steroidal and nonsteroidal anti-

inflammatory drugs to decrease pain and inflammation

• Disruption of destruction of joints by immune system

• Immune suppressants slow autoimmune reaction

• Some agents target tumor necrosis factor to block action of inflammatory chemicals

• Can replace joint with prosthesis


Figure 8.14 A hand deformed by rheumatoid arthritis.


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• Gouty arthritis• Deposition of uric acid crystals in joints and soft

tissues, followed by inflammation

• More common in men

• Typically affects joint at base of great toe

• In untreated gouty arthritis, bone ends fuse and immobilize joint

• Treatment: drugs, plenty of water, avoidance of alcohol and foods high in purines, such as liver, kidneys, and sardines



• Lyme disease• Caused by bacteria transmitted by tick bites

• Symptoms: skin rash, flu-like symptoms, and foggy thinking

• May lead to joint pain and arthritis

• Treatment• Long course of antibiotics


Developmental Aspects of Joints

• By embryonic week 8, synovial joints resemble adult joints

• Joint’s size, shape, and flexibility modified by use

• Active joints have thicker capsules and ligaments


Developmental Aspects of Joints

• Advancing years take toll on joints• Ligaments and tendons shorten and weaken

• Intervertebral discs more likely to herniate

• Most people in 70s have some degree of OA

• Full-range-of-motion exercise key to postponing joint problems


Joints - Des Moines Area Community College Boone...Figure 8.5d Movements allowed by synovial joints....

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Transcript of Joints - Des Moines Area Community College Boone...Figure 8.5d Movements allowed by synovial joints....