Lecture 8: Articulations (Joints)
I. Classification by Function
A. synarthroses - immoveable (sutures in cranium)
B. amphiarthroses - slightly moveable (tibia-fibula)
C. diarthroses - freely moveable (shoulder joint)
II. Fibrous Joints
A. Sutures
1. between cranial bones
2. very tight, thin layer of connective tissue
3. synostoses - bone replaces connective in adult
B. Syndesmoses
1. very little freedom for movement
2. interosseous membrane/ligament present
C. Gomphoses
1. one part fit tightly into the other
2. periodontal tissue holds parts firmly together
3. example: teeth in the mandible and maxillae
III. Cartilaginous Joints
A. Synchondrosis
1. hyaline cartilage --> bone over time
2. example: area between epiphysis & diaphysis of bone
3. example: joint between ribs and sternum
B. Symphysis
1. bones connected by disc of fibrocartilage
2. allows for slight movement (amphiarthrotic)
3. example: pubic symphysis, intervertebral discs
IV. Synovial Joints
A. Structure
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any joint where there is a space between bones
synovial cavity - space between the bones
freely moveable joints (diarthrotic)
articular cartilage - covers articular surface
articular capsule - encloses the cavity itself
a. fibrous capsule - attached to periosteum
i. ligaments - clearly defined connections
b. synovial membrane - inner layer of capsule
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i. produces synovial fluid
ii. reduces friction in the joint
6. accessory ligaments - additional support
a. extracapsular - outside capsule
b. intracapsular - within capsule
7. articular discs (menisci) - pads between bones
8. bursae - sac-like structures that reduce friction
a. between tendons, muscle, ligaments: and bone
B. Factors that Limit Movement in a Joint
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"fit" between the articulating bones
tension of the ligaments
arrangement and tension of the muscles
opposition of muscles restricting range of motion
C. Types of Movements in the Joint
limb
1. gliding - one bone slides over another (carpals)
2. angular motion - change the angle between bones
a. flexion - decrease the angle
b. extension - increase the angle
c. abduction - away from the midline
d. adduction - toward the midline
3. rotation - circular motion of the long axis
4. circumduction - distal end moves in a circle
5. inversion - sole of foot moves medially
6. eversion - sole of the foot moves laterally
7. dorsiflexion - raising foot toward lower limb
8. plantar flexion - extending foot away from lower
9. protraction - forward in the horizontal plane
10. retraction - backward in the horizontal plane
11. pronation - radius "radiates" over the ulna
12. supination - forearm returns to anatomical position
13. elevation - upward motion, in a superior direction
14. depression - downward motion, inferior direction
D. Types of Synovial Joints
1. gliding joints (arthrodia) (nonaxial)
a. side-to-side; back-and forth in grinding manner
b. carpals, tarsals, scapula-clavicle
2. hinge joints (ginglymus) (monaxial)
a. movement occurs in a single plane
b. elbow, ankle, interphalangeal
3. pivot joints (trochoid) (monaxial)
a. rotation around another bone
b. atlas-axis (C1-C2), proximal radius-ulna
4. ellipsoidal joints (condyloid) (biaxial)
a. side-to side; back-and-forth in smooth manner
b. radius-carpal joint in the wrist
5. saddle joints (sellaris) (biaxial)
a. one bone "sits" in the saddle of another
b. trapezium-thumb metacarpal joint
6. ball-and-socket joints (spheroid) (triaxial)
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a. works just like a joy-stick in all directions
b. humero-scapular joint; coxal (hip) joint
V. Examples of Major Articulations (Joints)
A. Humeroscapular Joint (Shoulder)
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head of humerus <--> glenoid cavity of scapula
ball-and-socket joint
articular capsule - surrounds entire joint
coracohumeral ligament
glenohumeral ligaments
transverse humeral ligament
glenoid labrum - fibrocartilage around glenoid fossa
bursae of the shoulder
a. subscapular, deltoid, acromial, coracoid
B. Femorocoxal Joint (Hip)
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head of femur <--> acetabulum of coxal bone
ball-and-socket joint
articular capsule -surrounds entire joint
iliofemoral ligament
pubofemoral ligament
ischiofemoral ligament
capitate ligament - acetabulum --> head of femur
acetabular ligament - fibrocartilage around acetab.
transverse ligament of acetabulum
C. Tibiofemoral Joint (Knee)
1. Three Joints in One
a. patellofemoral joint
b. medial tibiofemoral joint
c. lateral tibiofibular joint
2. articular capsule
3. ligaments: patellar, oblique popliteal, arcuate
popliteal, tibial collateral, fibular collateral
4. intraarticular ligaments
a. anterior cruciate ligaments
b. posterior cruciate ligaments
5. articular discs
a. medial meniscus
b. lateral meniscus
6. bursae: anterior, medial, lateral
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