Articulations!!

(the Joints)

Section 1: Joint Design and Movement

• Articulations (_____________________)– Where two bones interconnect– Bones are relatively inflexible so necessary to

allow movement– Reflect compromise between need for strength

versus need for ______________________– Anatomical structure of each joint determines

type and amount of movement possible• Categories from range of motion and subgroups from

anatomical structure

Joint types

• No Movement– Have we seen this before?

• Limited Movement– Can you think of any?

• Free Movement– Examples?

Joint Design and Movement

• Three functional categories1. _______________________ (no movement)2. Amphiarthrosis (little movement)3. ____________________________ (free movement)– Synarthrotic and amphiarthrotic joints

• Relatively simple structure• Direct connections between bones

– Diarthrotic joints• Complex in structure• Permit greatest range of motion

Synovial joints

• Components of synovial joints– ___________________

cartilages• Resemble hyaline

cartilages– Matrix contains more

water comparatively• Have no perichondrium• Slick and smooth, so

reduce friction• Are separated by thin film

of synovial fluid

Articular Cartilage

Components of synovial joints (continued)

– ______________ fluid• Similar in texture to egg

whites • Produced at the synovial

membrane• Circulates from areolar

tissue to joint cavity• Percolates through

articular cartilages• Total quantity is less than

3 mL

Synovial fluid

Components of synovial joints (continued)

– _________________ capsule• Dense and fibrous• May be reinforced with

accessory structures (tendons and ligaments)

• Continuous with periosteum of each bone

Joint capsule

Functions of synovial fluid

– Lubrication• With articular cartilage compression, synovial fluid is squeezed out

and reduces friction between moving surfaces– _______________________________ distribution

• Provide nutrients and oxygen, as well as waste disposal for the chondrocytes of articular cartilages

• Compression and reexpansion of articular cartilages pump synovial fluid in and out of cartilage matrix

– ________________________ absorption• Distributes compression forces across articular surfaces and

outward to joint capsule

Joint Accessory

– ____________________ (a pouch)• Small pocket filled with

synovial fluid• Often form in areas

where tendon or ligament rubs against other tissues

• Reduce friction and act as shock absorbers

Bursa

Accessory structures in knee (continued)

– Fat pads• Adipose tissue covered by

synovial membrane• Protect articular cartilages• Act as packing material for

joint

– _____________________ (a crescent)• Pad of fibrous cartilage

between bones of synovial joint

• May subdivide joint cavity and affect fluid flow or allow variations in shapes of articular surfaces

Meniscus

Fat pad

• Accessory structures in knee– Tendons of

quadriceps• Pass across joint

– Limit movement

– Provide mechanical support

• Accessory ligaments• __________________,

strengthen, and reinforce joint• Intrinsic ligaments

– Localized thickening of joint capsule– Example: cruciate liagments of knee

• ___________________ ligaments– Separate from joint capsule– May pass inside (intracapsular) or

outside (extracapsular) the joint capsule

– Intracapsular example: cruciate ligaments

– Extracapsular example: patellar ligament

Synovial joints

• _________________ vs. strength in joints– Greater range of motion = ______________

joint• Examples:

– Synarthrosis (strongest type of joint, no movement)– Diarthrosis (far weaker but broad range of motion)

– _____________________________ (luxation)• Movement beyond normal range of motion• Articulating surfaces forced out of position• Can damage joint structures• No pain from inside joint but from nerves or

surrounding structures

Types of motion and structural types of synovial joints

– _____________________• Movement along two axes in

one plane– Angular motion

• Movement along two axes in one plane with additional change in angle

– ______________________– Special complex angular

movement– Proximal end of bone

remains fixed while distal end can move in a circle (“trace circumference”)

– Rotation• Bone ends remain fixed and

shaft rotates

Figure 8.2 6

Gliding joint

Hinge joint

Pivot joint

Ellipsoid joint

Saddle joint

Ball-and-socket joint

The anatomical types of synovial joints, with joint models and examples

Types of Synovial Joints Models of Joint Motion Examples

Manubrium

Clavicle

Ulna

Humerus

Atlas

Axis

Scaphoid bone

UlnaRadius

Metacarpal boneof thumb

Trapezium

Scapula

Humerus

• Acromioclavicular and claviculosternal joints• Intercarpal and intertarsal joints• Vertebrocostal joints• Sacro-iliac joints

• Elbow joints• Knee joints• Ankle joints• Interphalangeal joints

• Atlas/axis• Proximal radio-ulnar joints

• Radiocarpal joints• Metacarpophalangeal joints 2–5• Metatarsophalangeal joints

• First carpometacarpal joints

• Shoulder joints• Hip joints

• Flexion and extension– Usually applied to

movements of long bones of limbs but also axial skeleton

– ______________________• Anterior/posterior

movement that reduces angle between articulating elements– Lateral flexion

» Vertebral column bending to the side

– Dorsiflexion» Flexion at ankle joint

and elevation of sole– ___________________

flexion (planta, sole)» Extension at ankle

joint and elevation of heel

– Extension• Anterior/posterior

movement that increases angle between articulating elements– __________________

» Extension past anatomical position

• Abduction and Adduction– Always refers to movements

of appendicular skeleton, not axial

– Movements are usually toward or away from body midline• For fingers or toes,

movements are spreading digits apart or bringing them together

– ____________________ (ab, from)• Movement away from body

longitudinal axis in frontal plane

– ____________________ (ad, to)• Movement toward body

longitudinal axis in frontal plane

• Circumduction– Moving arm or thigh as

if to draw a big _________________ at distal end of limb

• Wrist• Arm

• Rotation– When applied to the

trunk, described as left and right _____________________

– When applied to limbs• Medial rotation (internal

or inward rotation)– Anterior surface of limb

toward trunk long axis• Lateral rotation (external

or outward rotation)– Anterior surface of limb

away from trunk long axis

• Rotation (continued)– Other special terms for

rotation of forearm• ____________________

– Proximal end of radius rotates near ulna

– Distal end rolls across anterior ulnar surface

– Turns the wrist and hand from palm facing front to palm facing back

• ____________________– Opposing movement– Palm is turned

anteriorly

• Special movements– _______________________

• Movement of thumb toward palm surface or other fingers– Protraction

• Movement forward in anterior plane– ___________________

• Reverse of protraction– Inversion (in, into + vertere, to turn)

• Twisting foot motion to turn sole inward– ________________________ (e, out)

• Opposing movement to inversion

Figure 8.4 2

Special movements

Opposition

Eversion Inversion

Retraction Protraction

Depression Elevation

Articulations

• ____________________skeleton articulations– Typically are strong but very little movement

• ___________________________ skeleton articulations– Typically have extensive range of motion– Often weaker than axial articulations

Figure 8 Section 2 1

Joints of theAxial Skeleton

Sutures of the skull

Temporomandibular joint(temporal bone andmandible)

Atlanto-occipital joint(occipital bone and atlas)and the atlanto-axial joint(C1–C2)

Joints of the thoracic cage

Intervertebral joints

The lumbosacral joint,which attaches the lastlumbar vertebra to thesacrum

The sacrococcygeal andintercoccygeal joints,which structurallyresemble simplifiedintervertebral joints

Figure 8 Section 2 2

Joints of the foot and toes

Ankle joint

Knee joint

Hip joint

Joints of the handand fingers

Wrist joint

Pubic symphysis

Superior and inferiorradio-ulnar joints

Elbow joint

The sacro-iliac joint, whichfirmly attaches the sacrumof the axial skeleton to thepelvic girdle of theappendicular skeleton

Shoulder joint

The sternoclavicular joint,the only articulation betweenthe axial skeleton and thepectoral girdle and upperlimb

Joints of theAppendicular Skeleton

• Vertebral articulations– Between superior and inferior articular processes

of adjacent vertebrae• Gliding ______________________________ joints

– Permit flexion and rotation

– Adjacent vertebral bodies form symphyseal joints with _______________________________ discs

– Numerous ligaments attach bodies and processes of vertebrae to stabilize column

• Intervertebral discs– Composition

• __________________________ fibrosis– Tough outer layer of fibrous cartilage– Collagen fibers attach to adjacent vertebrae

• ___________________ pulposus– Soft, elastic, gelatinous core– Provides resiliency and shock absorption

– Account for ¼ length of vertebral column• Water loss from discs causes shortening of vertebral

column with age and increases risk of disc injury

Figure 8.5 2

The ligaments attached to the bodies and processes of all vertebrae

Primary Vertebral Ligaments

Ligamentum flavum

Posterior longitudinal ligament

Interspinous ligament

Supraspinous ligament

Anterior longitudinal ligament

Lateral view Sectional view

Posteriorlongitudinalligament

Spinal nerve

Spinal cord

Anulus fibrosus

Nucleus pulposus

Intervertebral disc

• Primary vertebral ligaments– Ligamentum ______________________

• Connects adjacent vertebral laminae– Posterior longitudinal ligament

• Connects posterior surfaces of adjacent vertebral bodies– Interspinous ligament

• Connects spinous processes of adjacent vertebrae– Supraspinous ligament

• Connects spinous processes from sacrum to C7 – Ligamentum nuchae from C7 to base of skull

– _______________________________ longitudinal ligament• Connects anterior surfaces of adjacent vertebral bodies

• Disorders of vertebral column– _______________________ disc• Posterior longitudinal ligaments weaken causing more

pressure on discs• Nucleus pulposus compresses, distorts anulus fibrosus• Disc bulges into vertebral canal (doesn’t actually slip)

– ________________________ disc• Nucleus pulposus breaks through anulus fibrosus• Spinal nerves are often affected

• Disorders of vertebral column (continued)– ______________________

(penia, lacking)• Inadequate ossification

leading to loss of bone mass• Often occurs with age

beginning between ages 30 and 40

• More severe in women than men

• Osteoporosis (porosus, porous)– Bone loss sufficient to affect

normal function

Figure 8.5 5

The effects of osteoporosis on spongy bone

Clinical scan of a compressionfracture in a lumbar vertebra

Figure 8.5 5

The effects of osteoporosis on spongy bone

Normal spongy bone SEM x 25 SEM x 21Spongy bone withosteoporosis

Ball and Socket• Shoulder joint (glenohumeral

joint)– __________________ range

of motion of any joint– Most frequently dislocated

joint• Demonstrates stability

sacrificed for mobility• Most stability provided by

surrounding skeletal muscles, associated tendons, and various ligaments

– Ball-and-socket diarthrosis• Formed by head of humerus

and glenoid cavity of scapula

• Hip joint– Sturdy ball-and-socket joint

• Although not directly aligned with weight distribution along femur shaft, which can produce fractures of femoral neck or intertrochanteric region

– Permits _______________, extension, adduction, abduction, circumduction, and rotation

– Formed by head of femur and acetabulum of hip bone

Figure 8.6 5

Greatertrochanter

Inter-trochantericline

Lesser trochanter Anterior view

The ligaments of the hip joint in anterior view

The ligaments of the hip joint in posterior view

Posterior view

Ischialtuberosity

Pubofemoral ligament

Iliofemoral ligament

Ischiofemoral ligament

Reinforcing Ligaments

The ligaments of the hip joint

Hinge• Elbow joint

– Complex __________________ joint involving humerus, radius, and ulna

– Extremely strong and stable due to:

1. Bony surfaces of humerus and ulna interlock

2. Single, thick articular capsule surrounds both humero-ulnar and proximal radio-ulnar joints

3. Articular capsule reinforced by strong ligaments

– Severe stresses can still produce dislocations or other injuries• Example:

___________________ elbow– Muscles flexing elbow attach on

anterior while those extending attach on the posterior

Figure 8.7 1

The elbow joint

Humeroulnar joint

Posteriorview

Olecranonfossa

Olecranon

Ulna

Humerus

Elbow and knee joints

• Elbow joint (continued)– Specific joints of the elbow• _____________________joint

– Capitulum of humerus articulating with head of radius

• Humero-ulnar joint– Largest and strongest articulation– Trochlea of humerus articulates with trochlear notch of ulna– Shape of ulnar notch determines plane of movement– Shapes of olecranon fossa and olecranon limit degree of extension

• Proximal radio-ulnar joint is ___________part of elbow joint

Elbow and knee joints

• Elbow joint (continued)– Reinforcing ligaments• Radial _________________ ligament

– Stabilizes lateral surface of joint

• Ulnar collateral ligament– Stabilizes medial surface of joint

• ____________________ ligament– Binds head of radius to ulna

Elbow and knee joints

• Knee joint– Contains

_____________separate articulations

1. Medial condyle of tibia to medial condyle of femur

2. Lateral condyle of tibia to lateral condyle of femur

3. Patella and patellar surface of femur

– Permits flexion, extension, and very limited _______________

Elbow and knee joints

• Knee joint (continued)– External support

• Quadriceps tendon to patella– Continues as patellar ligament to anterior tibia

• Fibular collateral ligament– Lateral support

• Tibial collateral ligament– Medial support

• _________________________ligaments– Posterior support extending between femur and heads of tibia and

fibula• Tendons of several muscles that attach to femur and tibia

Elbow and knee joints

• Knee joint (continued)– Internal support• ___________________ ligaments limit

anterior/posterior movement of femur and maintain alignment of condyles– Anterior cruciate ligament (ACL)

» At full extension, knee becomes “locked” (slight lateral rotation tightens ACL, and lateral meniscus forced between tibia and femur)

» Opposite motion to “unlock”– Posterior cruciate ligament (PCL)

Elbow and knee joints

• Knee joint (continued)– Internal support (continued)• Medial and lateral _______________

– Fibrous cartilage pads between tibial and femoral condyles

– Act as cushions and provide lateral stability to joint

Disruption to normal joint function

• Arthritis– Damage to articular cartilages but specific cause varies

• Exposed surfaces change from slick, smooth-gliding to rough feltwork of collagen fibers increasing friction

• Rheumatism (pain and stiffness affecting the skeletal and/or muscular systems) is often a symptom

– Osteoarthritis• Also known as degenerative arthritis or degenerative joint disease• Generally affects individuals age 60 and older

– 25% of women, 15% of men• Can result from cumulative wear and tear of joints or genetic factors

affecting collagen formation

Figure 8.8 1 – 2

Comparisons of normal articular cartilage with articular cartilage damaged by osteoarthritis

Normal Joint Arthritic Joint

Articularcartilage

LM x 180

Fibrousremainsof thearticularcartilage

Degeneratingarticularcartilage

LM x 180

Arthroscopic view of normal cartilage Arthroscopic view of damaged cartilage

Disruption to normal joint function

• Visualizing problematic joints– Arthroscopic surgery• Optical fibers (arthroscope) inserted into joint through

small incision without major surgery to visualize joint interior

• If necessary, other instruments can be inserted through other incisions to permit surgery within view of arthroscope

– _____________________ resonance imaging• Cost-effective and noninvasive viewing technique that

allows examination of soft tissues around joint as well

Figure 8.8 3

An arthroscopic view of the interior of the left knee,showing injuries to the anterior and

posterior cruciate ligaments.PCL

ACL

Femoralcondyle

Meniscus

Figure 8.8 4

Disruption to normal joint function

• _____________________ joints– May be last resort if other solutions (exercise,

physical therapy, drugs) for joint problems fail– Not as strong as natural joints, so most suitable for

elderly– Typically have service life of about 10 years

Figure 8.8 5

Next Monday

• Exam: Framework• Start new section: Organization!