Joints & Joint Movements Human Anatomy Sonya Schuh-Huerta, Ph.D.

Joints & Joint MovementsJoints & Joint Movements

Human AnatomyHuman AnatomySonya Schuh-Huerta, Ph.D.Sonya Schuh-Huerta, Ph.D.

Joints• Rigid elements of the skeleton meet at

joints or articulations

• Greek root “arthro” means joint

• Structure of joints– Enables resistance to

crushing, tearing, &

other forces

Classifications of Joints

• Joints can be classified by function or structure

• Functional classification based on amount of movement– Synarthroses immovable; common in

axial skeleton– Amphiarthroses slightly movable;

common in axial skeleton– Diarthroses freely movable; common in

appendicular skeleton (all synovial joints)


• Structural classification based on– Material that binds bones together– Presence or absence of a joint cavity– Structural classifications include:

• Fibrous• Cartilaginous• Synovial


Sutures – A Type of Fibrous Joint

• Bones are tightly bound by a minimal amount of fibrous tissue

• Only occur between the bones of the skull

• Allow bone growth so the skull can expand with brain during childhood

• Fibrous tissue ossifies in middle age– Synostoses = closed sutures

Syndesmoses – A Type of Fibrous Joint

• Bones are connected exclusively by ligaments

• Amount of movement depends on length of fibers– Tibiofibular joint = immovable synarthrosis– Interosseous membrane between radius &

ulna = freely movable diarthrosis

Gomphoses – A Type of Fibrous Joint

• Tooth in a socket

• Connecting ligament the periodontal ligament

Fibrous Joints

Densefibrousconnectivetissue

Sutureline

Root oftooth

Socket of alveolarprocess

Periodontalligament

FibulaTibia

Ligament

(a) Suture

Joint held together with veryshort, interconnecting fibers,

and bone edges interlock.Found only in the skull.

(b) Syndesmosis

Joint held together by aligament. Fibrous tissue canvary in length but is longer

than in sutures.

(c) Gomphosis

Peg-in-socket fibrous joint.Periodontal ligament holds

tooth in socket.

Cartilaginous Joints

• Bones are united by cartilage

• Lack a joint cavity

• 2 types– Synchondroses– Symphyses

Synchondroses

• Hyaline cartilage unites bones– Epiphyseal plates– Joint between first rib & manubrium

Epiphysealplate (temporaryhyaline cartilagejoint)

Sternum(manubrium)

Joint betweenfirst rib and sternum (immovable)

(a) Synchondroses

Bones united by hyaline cartilage

Symphyses

• Fibrocartilage unites bones; resists tension & compression

• Slightly movable joints that provide strength with flexibility– Intervertebral discs– Pubic symphysis

• Hyaline cartilage present as articular cartilage

Symphyses

Fibrocartilaginousintervertebraldisc

Pubic symphysis

Body of vertebra

Hyaline cartilage

(b) Symphyses

Bones united by fibrocartilage

Synovial Joints

• Most movable type of joint!!!• All are diarthroses what does that mean?

• Each contains a fluid-filled joint cavity

General Structure of Synovial Joints

• Articular cartilage– Ends of opposing bones are covered with

hyaline cartilage– Absorbs compression

• Joint cavity (= synovial cavity)– Unique to synovial joints– Cavity is a potential space that holds a small

amount of synovial fluid


• Articular capsule joint cavity is enclosed in a 2-layered capsule– Fibrous capsule dense irregular

connective tissue, which strengthens joint– Synovial membrane loose connective

tissue• Lines joint capsule & covers internal joint surfaces• Makes synovial fluid


• Synovial fluid– A viscous fluid similar to raw egg white

• A filtrate of blood– Arises from capillaries in synovial membrane

• Contains glycoprotein molecules secreted by fibroblasts


• Reinforcing ligaments– Often are thickened parts of the fibrous

capsule– Sometimes are extracapsular ligaments

located outside the capsule– Sometimes are intracapsular ligaments

located internal to the capsule

Periosteum

Ligament

Fibrouscapsule

Synovialmembrane

Joint cavity (contains synovial fluid)

Articular (hyaline)cartilage

Articularcapsule

(a) A typical synovial joint



• Richly supplied with sensory nerves– Detect pain– Most monitor how much the capsule is being

stretched


• Have a rich blood supply– Most supply the synovial membrane– Extensive capillary beds produce basis of

synovial fluid– Branches of several major nerves & blood

vessels

Synovial Joints with Articular Discs

• Some synovial joints contain an articular disc– Temporomandibular joint & Knee joint– Occur in joints whose articulating bones have

somewhat different shapes

How Synovial Joints Function

• Synovial joints lubricating devices

• Friction could overheat & destroy joint tissue & bone ends

• Are subjected to compressive forces• Fluid is squeezed out as opposing cartilages touch• Cartilages ride on the slippery film

Bursae & Tendon Sheaths

• Bursae & tendon sheaths are not synovial joints– Closed bags of lubricant– Reduce friction between body elements

• Bursa = a flattened fibrous sac lined by a synovial membrane

• Tendon sheath = an elongated bursa that wraps around a tendon

Bursae & Tendon Sheaths

Acromionof scapula

Joint cavitycontainingsynovial fluid

Synovialmembrane

Fibrouscapsule

Humerus

Hyalinecartilage

Coracoacromialligament

Subacromialbursa

Fibrousarticular capsule

Tendonsheath

Tendon oflong headof bicepsbrachii muscle

(a) Frontal section through the right shoulder joint


Subacromialbursa

Cavity inbursa containingsynovial fluid

(b) Enlargement of (a), showing how a bursa eliminates friction where a ligament (or other structure) would rub against a bone

Humerus resting

Humerus moving

Bursa rollsand lessens friction.

Humerus headrolls medially as arm abducts.

Movements Allowed by Synovial Joints

• 3 basic types of movement– Gliding one bone across the surface of

another– Angular movement movements change

the angle between bones– Rotation movement around a bone's long

axis

Gliding Joints

• Flat surfaces of two bones slip across each other

• Gliding occurs between: – Carpals– Articular

processes of vertebrae

– Tarsals

Gliding

(a) Gliding movements at the wrist

Angular Movements

• Increase or decrease angle between bones

• Movements involve:– Flexion & extension– Abduction & adduction– Circumduction

Angular Movements

(b) Angular movements: flexion & extension of the neck

Extension

Flexion

Angular Movements

Flexion

Extension

(c) Angular movements: flexion & extension of the trunk

Angular Movements

Extension

Extension

Flexion

Flexion

(d) Angular movements: flexion & extension at the shoulder and knee

Angular Movements

Abduction

Adduction

(e) Angular movements: abduction, adduction, & circumduction of the upper limb at the shoulder

Circumduction

PLAYPLAYMovement of theglenohumoral joint

Rotation

• Involves turning movement of a bone around its long axis

• The only movement allowed between atlas & axis vertebrae

• Occurs at the neck, shoulder, elbow, hip

Rotation

Lateralrotation

Medialrotation

(f) Rotation of the head, neck, & lower limb

Rotation

Special Movements

• Elevation lifting a body part superiorly

• Depression moving the elevated part inferiorly

Elevationof mandible

Depressionof mandible

Elevation

Depression

Special Movements

• Protraction nonangular movement anteriorly

• Retraction nonangular movement posteriorly

Protractionof mandible

Retractionof mandible

ProtractionMoving a body part in theanterior direction

RetractionMoving a body part in theposterior direction

Special Movements

• Supination forearm rotates laterally, palm faces anteriorly

• Pronation forearm rotates medially, palm faces posteriorly– Brings radius across the ulna

Special MovementsSupination(radius and ulnaare parallel)

Pronation (P) Rotating the forearm so the palm faces posteriorly

Supination (S)Rotating the forearm so thepalm faces anteriorly

Pronation(radius rotatesover ulna)

Special Movements

• Opposition thumb moves across the palm to touch the tips of other fingers

Opposition

Special Movements

• Inversion & eversion– Special movements at the foot

• Inversion turns sole medially• Eversion turns sole laterally

EversionInversion

Inversion Turning the sole of the foot medially

EversionTurning the sole of the footlaterally

Special Movements

Special Movements

• Dorsiflexion & plantar flexion– Up-and-down movements of the foot– Dorsiflexion lifting the foot so its superior

surface approaches the shin– Plantar flexion depressing the foot,

elevating the heel (ballet toe point)

Special MovementsDorsiflexion

Plantar flexion

Dorsiflexion Lifting the foot so its superior surface approaches the shin

Plantar flexionDepressing the footelevating the heel

PLAYPLAYEversion ofAnkle joint (5a)

Synovial Joints Classified by Shape

• Plane joint– Articular surfaces are flat planes– Short gliding movements are allowed

• Intertarsal & intercarpal joints• Movements are nonaxial• Gliding does not involve rotation around any axis

Plane Joint

(a) Plane joint

Gliding

Metacarpals

Carpals

Nonaxial movement


• Hinge joints– Cylindrical end of one bone fits into a trough

on another bone– Angular movement is allowed in one plane– Elbow, ankle, & joints between phalanges– Movement is uniaxial allows movement

around one axis only

Hinge Joint

(b) Hinge joint

Medial/lateralaxis

Flexion & extension

Humerus

Ulna

Uniaxial movement


• Pivot joints– Classified as uniaxial – rotating bone only

turns around its long axis– Examples

• Proximal radioulnar joint• Joint between atlas & axis

Pivot Joint

(c) Pivot joint

Ulna

Verticalaxis

RotationRadius


• Condyloid joints– Allow moving bone to travel:

• Side to side abduction-adduction• Back & forth flexion-extension

– Classified as biaxial = movement occurs around 2 axes

– Phalanges

Condyloid Joint

(d) Condyloid joint

Medial/lateralaxis

Adduction &abduction

Flexion &extension

Metacarpals

Phalanges

Anterior/posterioraxis

Biaxial movement


• Saddle joints– Each articular surface has concave & convex

surfaces– Classified as biaxial joints– 1st carpometacarpal joint is a good example

• Allows opposition of the thumb

Saddle Joint

(e) Saddle joint

Anterior/posterior axis

Medial/lateralaxis

Adduction andabduction

Metacarpal 1

Trapezium

Flexion andextension


• Ball-and-socket joints– Spherical head of one bone fits into round

socket of another– Classified as multiaxial allow movement in

all axes• Shoulder & hip joints are examples

Ball-and-Socket Joint

(f) Ball-and-socket joint

Medial/lateralaxis

Anterior/posterioraxis

Verticalaxis

RotationAdductionand abduction

Flexion andextension

Scapula

Humerus

Multiaxial movement

PLAYPLAYMovement of theglenohumeral joint (a)

Factors Influencing Stability of Synovial Joints

• Articular surfaces– Shapes of articulating surfaces determine

movements possible


• Ligaments– Capsules & ligaments prevent excessive

motions– On the medial or inferior side of a joint

prevent excessive abduction– Lateral or superiorly located resist

adduction


• Ligaments (cont…)– Anterior ligaments resist extension &

lateral rotation– Posterior ligaments resist flexion & medial

rotation

• The more ligaments usually the stronger & more stable


• Muscle tone– Helps stabilize joints by

keeping tension on tendons

– Is important in reinforcing:• Shoulder & knee joints• Supporting joints in arches of the foot

Selected Joints

Selected Synovial Joints

• Temporomandibular Joint– Is a modified hinge joint– The head of the mandible articulates with the

temporal bone– Lateral excursion is a side-to-side movement– 2 surfaces of the articular disc allow:

• Hinge-like movement• Gliding of superior surface anteriorly

The Temporomandibular Joint

Zygomatic process

Mandibular fossa

Articular tubercle

Infratemporal fossa

Externalacousticmeatus

Articularcapsule

Ramus ofmandible

(a) Location of the joint in the skull

Lateralligament

Articularcapsule

Mandibularfossa

Articular disc

Articulartubercle

Superiorjointcavity

Inferior jointcavity

Mandibularcondyle

Ramus of mandible

Synovialmembranes

(b) Enlargement of a sagittal section through the joint (arrows indicate movement in each part of the joint cavity)

The Temporomandibular Joint


• Shoulder (= Glenohumeral) joint– The most freely movable joint (lacks stability!)– Articular capsule is thin & loose– Muscle tendons contribute to joint stability

The Shoulder JointAcromionof scapula

Synovial membrane

Fibrous capsule

Hyalinecartilage


Subacromialbursa

Fibrousarticular capsule

Tendonsheath

Tendon oflong headof bicepsbrachii muscle

(a) Frontal section through right shoulder joint

Synovial cavityof the glenoidcavity containingsynovial fluid

Glenoid labrum

Humerus

Fibrous capsule

Hyalinecartilage

Synovial cavityof the glenoidcavity containingsynovial fluid

Glenoid labrum

Humerus

(b) Cadaver photo corresponding to (a)

The Shoulder Joint

Glenohumeral Joint

• The rotator cuff is made up of 4 muscles & their associated tendons– Supraspinatus– Infraspinatus– Teres minor– Subscapularis (= SITS muscles)

• Rotator cuff injuries are common shoulder injuries

The Shoulder JointAcromionCoracoacromialligament

Subacromialbursa

Coracohumeralligament

Greatertubercleof humerus

Transversehumeralligament

Tendon sheath

Tendon oflong headof bicepsbrachiimuscle

Articularcapsulereinforced byglenohumeralligaments

Subscapularbursa

Tendon of thesubscapularismuscle

Scapula

Coracoidprocess

(c) Anterior view of right shoulder joint capsule

The Shoulder Joint

Acromion

Coracoidprocess

Articularcapsule

Glenoid cavity

Glenoid labrum

Tendon of longhead of bicepsbrachii muscle

Glenohumeralligaments

Tendon of thesubscapularismuscle

ScapulaPosterior Anterior

(d) Lateral view of socket of right shoulder joint, humerus removed

(e) Posterior view of an opened left shoulder joint

Head ofhumerus

Muscleof rotatorcuff (cut)

Acromion(cut)

Glenoidcavity ofscapula

Capsule ofshoulderjoint(opened)


• Elbow joint– Allows flexion & extension– The humerus’ articulation with the trochlear

notch of the ulna forms the hinge– Tendons of biceps & triceps brachii provide

stability

The Elbow JointArticularcapsule

Synovialmembrane

Synovial cavity

Articular cartilage

Coronoid process

Tendon ofbrachialis muscle

Ulna

Humerus

Fat pad

Tendon oftricepsmuscle

Bursa

Trochlea

Articular cartilageof the trochlearnotch

(a) Mid-sagittal section through right elbow (lateral view)

The Elbow Joint

Humerus

Lateralepicondyle

Articularcapsule

Radialcollateralligament

Olecranonprocess

(b) Lateral view of right elbow joint

Annularligament

Radius

Ulna

The Elbow JointArticularcapsule

Annularligament

Coronoidprocess

(d) Medial view of right elbow

Radius

Humerus

Medialepicondyle

Ulnarcollateralligament

Ulna

Wrist Joint

• Stabilized by numerous ligaments

• Composed of radiocarpal & intercarpal joint– Radiocarpal joint joint between the

radius & proximal carpals (the scaphoid & lunate)

• Allows for flexion, extension, adduction, abduction, & circumduction

– Intercarpal joint joint between the proximal & distal rows of carpals

• Allows for gliding movement

Wrist JointRadius Ulna

Lunate

Triquetrum

Pisiform

HamateCapitate

Scaphoid

Trapezoid

Trapezium

Thumb

Radiocarpaljoint

(a) Right wrist, anterior (palmar) view

Wrist JointDistalradioulnarjoint


ArticulardiscRadial

collateralligament

Radiocarpaljoint

Intercarpaljoint

(b) Wrist joints, coronal section

Wrist Joint

Hamate

Carpo-metacarpalligaments

Pisiform

Lunate

Radius Ulna


Radialcollateralligament

Palmarradiocarpalligament

Intercarpalligaments

Trapezium

Capitate

Scaphoid

(c) Ligaments of the wrist, anterior (palmar) view


• Hip joint– A ball-and-socket joint– Movements occur in all axes

• Limited by ligaments & acetabulum

– Head of femur articulates with acetabulum– Stability comes chiefly from acetabulum &

capsular ligaments – Muscle tendons contribute somewhat to

stability

PLAYPLAYMovement of thehip joint

The Hip Joint

Articular cartilage

Coxal (hip) bone

Ligament of thehead of the femur(ligamentum teres)

Synovial cavity

Articular capsule

Acetabular labrum

Femur

(a) Frontal section through the right hip joint

Anterior inferioriliac spine

Iliofemoralligament

Pubofemoralligament

Greatertrochanter

(d) Anterior view of right hip joint, capsule in place

The Hip Joint

Ischium

Iliofemoralligament

Ischiofemoralligament

Greatertrochanterof femur

(c) Posterior view of right hip joint, capsule in place


• Knee joint– The largest & most complex joint– Primarily acts as a hinge joint– Has some capacity for rotation when leg is flexed– Structurally considered compound & bicondyloid– 2 fibrocartilage menisci occur within the joint cavity– Femoropatellar joint shares the joint cavity

• Allows patella to glide across the distal femur

Sagittal Section of Knee Joint

(a) Sagittal section through the right knee joint

Femur

Tendon ofquadricepsfemoris

Suprapatellarbursa

PatellaSubcutaneousprepatellar bursa

Synovial cavity

Lateral meniscus

Posteriorcruciateligament

Infrapatellarfat pad

Deep infrapatellarbursa

Patellar ligament

Articularcapsule

Lateralmeniscus

Anteriorcruciateligament

Tibia

Superior View of Knee Joint

(b) Superior view of the right tibia in the knee joint, showing the menisci and cruciate ligaments

Medialmeniscus

Articularcartilage on medial tibial condyle

Anterior


Articularcartilage onlateral tibialcondyle

Lateralmeniscus


Anterior View of Knee

Quadricepsfemorismuscle

Tendon ofquadricepsfemorismuscle

Patella

Lateralpatellarretinaculum

Medialpatellarretinaculum

Tibialcollateralligament

Tibia

Fibularcollateralligament

Fibula

(c) Anterior view of right knee

Patellarligament

Knee Joint

• Ligaments of the knee joint:– Become taut when knee is extended– These extracapsular & capsular ligaments are:

• Fibular & tibial collateral ligaments• Oblique popliteal ligament• Arcuate popliteal ligament

Knee Joint

• Intracapsular ligaments– Cruciate ligaments

• Cross each other like an “X”

– Each cruciate ligament runs from the proximal tibia to the distal femur

• Anterior cruciate ligament (ACL) • Posterior cruciate ligament (PCL)

Anterior View of Flexed Knee

Fibularcollateralligament

Posterior cruciateligament

Medial condyle

Tibial collateralligament

Anterior cruciateligament

Medial meniscus

Patellar ligament

Patella

Quadricepstendon

Lateralcondyleof femur

Lateralmeniscus

Fibula

(e) Anterior view of flexed knee, showing the cruciate ligaments (articular capsule removed, and quadriceps tendon cut and reflected distally)

Tibia

Medial femoralcondyle

Anterior cruciateligament

Medial meniscuson medial tibialcondyle

Patella

(f) Photograph of an opened knee joint; view similar to (e)

Knee Joint

• Intracapsular ligaments– Cruciate ligaments prevent undesirable

movements at the knee• Anterior cruciate ligament prevents anterior

sliding of the tibia• Posterior cruciate ligament prevents forward

sliding of the femur or backward displacement of the tibia

Stabilizing function of cruciate ligaments During movement of the knee the anteriorcruciate prevents anterior sliding of the tibia; the posterior cruciate prevents posterior sliding of the tibia.


(a)


Quadricepsmuscle

Femur

Patella

Lateralmeniscus

Tibia

Medialcondyle

(b)



When the knee is fully extended,both cruciate ligaments are taut and the knee is locked.

1 2

The “Unhappy Triad”

• Lateral blows to the knee can tear:– Tibial collateral ligament & medial meniscus– Anterior cruciate ligament

– Are common sports injuries!

Selected Synovial Joint

• Ankle joint– A hinge joint between:

• United distal ends of tibia & fibula • The talus of the foot

– Allows the movements of:• Dorsiflexion & plantar flexion only

The Ankle Joint

– Medially & laterally stabilized by ligaments• Medial (deltoid) ligament• Lateral ligament

– Inferior ends of tibia & fibula are joined by ligaments

• Anterior & posterior tibiofibular ligaments

The Ankle Joint Tibia

Calcaneal tendon

Calcaneus

Navicularbone

Subtalarjoint

(a) Cadaver photo of ankle and foot, sagittal section

Intermediatecuneiform bone

Tendon of flexordigitorum longus

Metatarsal bone (II)

Interphalangeal joint

Metatarsophalangealjoint

Cuneonavicular joint

Talonavicular joint

Talocalcaneal ligament

Tibialis posterior muscle

Ankle (talocrural) joint

Tarsometatarsal joint

Talus

Ligaments of the Ankle Joint

Medial malleolus

Calcaneus

Sustentaculumtali

Medial (deltoid)ligament

Talus

Navicular

Tibia

1st metatarsal

(b) Right ankle, medial view

Ligaments of the Ankle Joint

Anterior tibiofibularligament

Anterior talofibularligament

Calcaneus

Metatarsals

Lateral malleolus

Posterior tibiofibularligament

Posterior talofibularligament Calcaneofibularligament

Tibia

Talus

Cuboid

Fibula

(c) Right ankle, lateral view

Lateralligament

Disorders of Joints

• Structure of joints makes them prone to traumatic stress

• Function of joints makes them subject to friction and wear & tear

• Affected by inflammatory & degenerative processes

Joint Injuries

• Torn cartilage common injury to meniscus of knee joint

• Sprains ligaments of a reinforcing joint are stretched or torn

• Dislocation occurs when the bones of a joint are forced out of alignment

Inflammatory & Degenerative Conditions

• Bursitis inflammation of a bursa due to injury or friction

• Tendonitis inflammation

of a tendon sheath

Swollen bursa surroundingthe knee

Inflammatory & Degenerative Conditions

• Arthritis describes over 100 kinds of joint-damaging diseases– Osteoarthritis most common type of “wear

& tear” arthritis– Rheumatoid arthritis a chronic

inflammatory disorder – Gouty arthritis (gout) uric acid build-up

causes pain in joints• Lyme disease inflammatory disease often

resulting in joint pain

The Joints Throughout Life

• Synovial joints develop from mesenchyme

• By week 8 of fetal development, joints resemble adult joints– Outer region of mesenchyme becomes fibrous

joint capsule– Inner region becomes the joint cavity

The Joints Throughout Life

• During youth injury may tear an epiphysis off a bone shaft; breaks near joints; dislocations

• Advancing age osteoarthritis becomes more common

• Exercise helps maintain

joint health!

Keeping Your Joints Healthy

• Exercise is key –

strengthens the muscles around

the joints & stabilizes them;

decreases injuries, joint disorders,

wear-&-tear, etc.

• Also good: proper nutrition, hydration, & vitamins/ supplements (glucosamine a good one)

The journey of a mother & daughter

Keeping Your Joints Healthy

Questions…?

What’s Next?Lab: Finish Bones & JointsWed Lecture: Skeletal muscle Wed Lab: Skeletal muscle tissue & muscles

Joints & Joint Movements Human Anatomy Sonya Schuh-Huerta, Ph.D.

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