ArticulationsAnatomy and Physiology

I. Classification of joints

• Articulation – point where 2 bones meet (joint)• Joints are classified according to amount and type of movements• 3 general types of joints• Immovable (synarthrosis)• Slightly immovable ( amphiarthrosis)• Freely movable (diarthrosis)

II. Immovable joints (synarthrosis)

• Joints fused together• 4 types

a. Suturesb. Gomphosesc. Synchondrosesd. synostoses

a. Sutures

• Between bones of skulls• Interlocked• Bound together by dense connective tissue

b. gomphoses

• teeth to bony sockets• held into socket by periodontal ligament

c. Synchondroses

• cartilage bridge between 2 articulating bones• ex. Ends of vertebrosternal rib and sternum

d. synostosis

• rigid immovable• bones fused together with no line of demarcation as to where it starts

or ends.•

• Ex. Hip, coccyx

III. Slightly movable (amphiarthrosis)• Permits more movement than syntarthrosis, but stronger than freely

movable joints• 2 types

1. syndesmosis2. symphysis

a. Syndesmosis (sin-dez-MO-sis)

• bones connected by a ligament• • ex. Tibia and fibula

b,. symphysis

• bones separated by wedge or pad of fibrocartilage

• ex. Vertebrae – vertebral disks• pubic bones – pubic symphysis

IV. Freely Movable (diarthroses)

• a. Aka – synovial joints• Allow large range of motion• Synovial joint surrounded by capsule and synovial membrane lines the

cavity• Found end of long bones• Surface slippery and smooth which decreases friction• Contains synovial fluid

b. 3 functions of synovial fluid

• i. lubricant the viscous fluid acts to lubricate the joints

ii. nutrient distributioncirculates to provide nutrients and rids waste productsmoves every time joint moves

iii. shock absorption cushionsdistributes pressure across the joint which lessens shock on the surfaces of joint

c. arthritis• affects syovial joints

damages to articulating cartilagescaused by injury, virus, bacteria, physical stress

2 types arthritisi. Osteoarthritis – • Degenerative• Results from cumulative wear and tear of joint surfaces• Genetic factors• 60 + older ii. Rheumatoid arthritis• Inflammation• Due to immune system mistakenly attacking joint tissue• Allergies, bacteria, virus, and genetics contribute to triggering

iii. Treatment of arthritis

• Exercises• Physical therapy• Meds (anti-inflamatory)• Replacement of joint

V. Accessory Structures of synovial jointsa. Fat padsb. Cartilage padsc. Ligamentsd. Tendonse. bursea

a. Fat pads

structure:• adipose tissue covered by layer of synovial membrane• superficial to joint capsule

function –• protect articulating cartilage• act as packing material for joint by filling in spaces created as joint

cavity moves.

b. Cartilage pads

structure:• fibrocartilage pad situated between bones within synovial joint

ex. Meniscus

function : • channel synovial fluid flow• absorb shock • subdivide synovial cavity

c. ligaments

i. Accessory:•thickenings of capsule•reinforces and strengthens capsule•limits rotation at joint

ii. extracapsular•connect articulating bones•passes across outside of capsule•support wall of jointex. Lateral collateral and medial collateral ligaments of knee

iii. Intracapsular• inside capsule•prevents extreme movements that could hurt joint ex. ACL , PCL

iv. other (ligaments of knee)• popliteal• patellar

d. tendons

• Connect muscle to bone• Across and around joints to provide strength to joints

• Tendonitis – inflammation of tendon

e. burseastructure• Small fluid filled sacs in connective tissue• Contain synovial fluid and lined by synovial membrane• Found where tendons and ligaments rub against other tissues• Function –• Decrease friction• Absorb shock

Bursitis – inflammation of bursae• Pain when move tendon or ligament• Associated with repetitive motion

Golfers, swimmers, pitchers, tennis

VI. Types of Movements

a. Glidingb. Angularc. Rotationd. Special movements

a. gliding

• Sliding past one another• Carpal bones• B/t tarsal bones• b/t clavicle and sternum• movement in any direction – but very slight

Ex:• touch process on clavicle and turn shoulders in – feel sliding

b. angular

Change in angle between shaft and joint1. Flexion – decrease in angle

ex. Chin to chest, touch toes, bend wrist2. Extension – increase in angleEx. Straightening leg or arm

3. Hyperextension – extension beyond anatomical positionex. Look at ceiling (hyperextend neck)

4. Abduction – movement of appendage AWAY from long axis of body (along frontal plane)

ex. Moving arm away from body, spreading fingers

5. Adduction – movement appendages TOWARD long axis of body (along frontal plane)Ex. Moving arm toward body, fingers together

6. Circumduction – Distal end of appendage moves in circle

Ex. Baseball wind up

c. Rotation

• in referent to anatomical position• depends on part moving

• ex. Head rotation – move chin to right or left (say NO) • ex. Limb rotation – medial – inward

lateral – outward Lower arm rotation• pronation – move palm toward back• supinate – move palm from back toward front

d. Special movementsFOOT:inversion • twisting motion of foot that turns sole inward

eversion • twisting motion of foot that turns sole outward

dorsiflexion • flexion of ankle and elevation of sole of foot (dig heel into ground)

plantar flexion • extend ankle and elevate heel (stand on tip toes)

Special mvmts. cont….opposition •thumb to fingers

protraction •moving body part anteriorly in horizontal plane

• ex. Sticking out tongue

retraction •opposite of protraction

elevation •structure moves superiorly

• ex. Shrug shoulders, close mouth,

depression •structure move inferior•open mouth lateral flexion •vertebral column bends to one side

• ex. Side stiches, move ear toward shoulder

VII. Types of Synovial Joints

Each synovial joint permits different type and range of motion

a. Glidingb. Hingec. Pivotd. Ellipsoidale. Saddlef. Ball and socket

a. Gliding

• Aka planar joints• Flattened or slightly curved faces• Flat articulating surfaces• Slight movement

Ex. Clavicle, carpals, tarsals, between vertebrae

b. Hinge joint

• Angular movement in single plane (monaxial joint)• Monaxial joint (only flexes or extends in one plane)

• Ex. Occipital condyle and atlas• Elbow, knee, interphalangeal joints , wrist

c. Pivot

• Monaxial• Permits rotation only

• Ex. Atlanto-axial joint (atlas and axis)Radioulnar joint

d. Ellipsoidal

• Aka condyloid joint• Nestles with in a depression• Angular motion in 2 planes – biaxial

(flexion/extension and abduction/adduction

• ex. Metacarpal phalangeal jointmetatarsalphalangeal jointwrist – radiocarpal joint

e. Saddle

• Aka sellaris joint• Articulating faces look like saddles • Angular motion – biaxial

Circumduction and angular motion (flexion /extension, etc)• Ex. Carpometacarpal joint (base of thumb – twiddle thumbs)

f. Ball and socket

• round head of bone fits in cup shaped depression of another bone• multiaxial – rotate, circumduction, angular movements)

• ex. Shoulder , hip

VIII. Major Joints in Human Body

a. Shoulder joint:• greatest range of motion• also most frequently dislocated• most stability provided by ligaments and muscles around joint• contain bursae to decrease friction between tissue

Shoulder joint cont…

rotator cuff:• supraspinatus• infraspinatus• subscapularis• teres minor

• primary support for shoulder joint and limits range of motion.• Injury to rotator cuff usually due to severe stress on shoulder, repetition

(pitchers, swimmers, quarterbacks , etc..)

b. elbow

• olecranon joint• hinge (flexion and extension)• diarthrosis• muscles that extend elbow attach at olecranon process (triceps)• muscles that flex elbow – attach at radial tuberosity• stable joint due to the fact that humerus and ulna interlock• has thick articular capsule and ligament reinforcement

c. hip

• diarthrosis• flexsion / extension, abduction/adduction, circumduction and rotation

• contains large muscles to help with stability of joint• ligaments around the hip include

iliofemoralpubofemoralischiofemoraltransverse acetabular ligamentligamentum teres

d. knee

• Hinge joint• Flexion / extension (monaxial)• Limited rotation

• Medial and lateral menisci lie between femoral and tibial surfaceCushions, gives lateral stability,

Knee cont.Ligaments of knee

Patellar ligament • Patella is within patellar tendon, continuation of this tendon = patellar ligament which attaches to anterior surface of tibia (tuberosity)

Popliteal ligaments (2)• Between femur and heads of tibia and fibula• Supports posterior surface Anterior and Posterior Cruciate• Inside joint capsule• Criss cross inside capsule• Limit anterior and posterior movement of femur and maintain alignment of femoral and tiaeal condyles. Tibial (medial ) collateral (MCL)• Reinforces medial surface of knee

Fubular (lateral) collateral (LCL)• Reinforces lateral surface of knee

IX. Male vs. Female Skeleton• General differences:• Males bones larger than female• Males have larger muscle attachment surfaces• Males have larger Joint surfaces

• Skull :• Males have shorter forehead• Males mandible and maxillae larger• Males facial area is more pronounced

• Pelvis:• Males pelvis narrower• Males pelvis deeper• Males pelvic outlet smaller• Males subpubic angle less than 90 degrees

X. Common Disorders of Skeletal System

1. Arthritis – inflammation of joint, pain stiffness• Osteoarthritis – wear and tear• Rheumatoid -

2. Bunion• Bony bump that forms on the joint at the base of your great toe.• Wearing tight or narrow shoes can form bunions. Sometimes just inherent structural defect.

3. Bursitis• Inflammation of fluid filled sac• Overuse or repetitive movement

4. Gout• Missing enzyme causes uric acid build up in joints• Common in toe, knee

5. Herniated disc• When vertebral disk “pops” out from between vertebrae

Disorders cont…..6. Luxation• Full dislocation of a joint• Usually from fall or unusual movement

• Shoulder, knees, shoulder, fingers, jaw

7. Subluxation• Partial dislocation of a joint

8. Sprain• Overstretching or tearing of connective tissue, ligaments and tendons

9. Strain• Overstretching or over use of muscle