Bio 150- Articulations

Question 1

Articulations

Answer 1

• Where two (or more) bones come together
• May be moveable (but not all are!)
• Hold skeleton together, give us mobility…
• Can be classified based on their function or their structure

Question 2

Definition Functional classification:

Answer 2

based on type of movement allowed by that joint

Question 3

Definition Structural classification:

Answer 3

based on material that binds the bones together, and presence/absence of a joint cavity

Question 4

Functional classification of articulations

Answer 4

Synarthroses: immovable joints

Amphiarthroses: slightly movable joints

Diarthroses: freely movable joints

Question 5

Structural classification of articulations

Answer 5

-Bony and/or Fibrous (1 or 2 categories…):
Bones joined by fibers (eg., collagen), no cavity
Most are immovable

-Cartilaginous:
Bones joined by cartilage, no cavity
Most are slightly movable or immovable

-Synovial
Bones in the joint are separated by a fluid-filled cavity, and enclosed in a capsule
Freely movable

Question 6

Bony joints =

Answer 6

synostoses

• Immovable (= synarthrosis)
• Gap between two bones becomes ossified: Essentially forms one bone!
• Example: R & L frontal bones fuse to form one frontal bone

Question 7

Fibrous joints: 3 types

Answer 7

Sutures
Syndesmoses
Gomphoses

Question 8

Sutures (Fibrous joints)

Answer 8

-Between bones of skull
Short, CT fibers, continuous with periosteum
-May become synostoses once the fibrous tissue ossifies (middle age)
-Functional classification: synarthroses (immovable)

Question 9

Syndesmoses (Fibrous joints)

Answer 9

• Bones connected by a ligament
• Longer fibers
• Slight to considerable movement…
• Functional classification: amphiarthroses (slightly movable) or synarthroses (immovable)

Question 10

Gomphoses (Fibrous joints)

Answer 10

-Peg-in-socket
-Articulation of a tooth with its bony socket
-Fibrous connection is the periodontal ligament
-Synarthroses (Immovable)
But a tiny bit of movement…

Question 11

Cartilaginous joints: 2 types

Answer 11

Synchondroses

Symphyses

Question 12

Synchondroses (Cartilaginous joints)

Answer 12

• Bones are united by a bar/plate of hyaline cartilage
• Immovable (synarthroses)
• Example: costal cartilage of first rib with manubrium of the sternum

Question 13

Symphyses (Cartilaginous joints)

Answer 13

• Articular cartilage (hyaline cartilage) of bone ends is fused to a pad/plate of fibrocartilage
• Compressible and resilient! A shock absorber
• Strength plus flexibility
• Amphiarthroses (slightly moveable)

Question 14

Synovial joints

Answer 14

-All joints of the limbs (most joints of the body)
-Bones separated by a fluid filled cavity
-All are freely movable on 1, 2 or more axes
-Compromise between strength/stability and flexibility (as we’ll discuss…)
-May be stabilized by:
Shape of articular surfaces
Ligaments
Muscle tone

Question 15

Synovial joints: distinguishing features

Answer 15

• Articular cartilage
• Joint (synovial) cavity
• Articular capsule
• Synovial fluid
• Reinforcing ligaments

-May also include: fatty pads, menisci (articular discs)

Question 16

Movements allowed by synovial joints: (6)

Answer 16

Gliding
Saddle
Hinge
Pivot
Ball and Socket
Condylar (Ellipsodial)

Question 17

Bursae and tendon sheaths

Answer 17

• “Bags of lubricant”, act as ball bearings

- Reduce friction

Question 18

Bursae:

Answer 18

= flattened fibrous sac, lined with synovial membrane, contains some synovial fluid
-Common where structures in a joint rub together (ligaments, muscles, skin, tendons, bones…)

Question 19

Tendon sheath:

Answer 19

= a bursa that wraps “around” a tendon

-Common where a tendon is subjected to friction

Question 20

Major joints of the body:

Answer 20

• Shoulder (rotator cuff)
• Elbow
• Hip
• Knee