Lecture 4: Articulations and Frames

Question 1

Articulations

Answer 1

Places where 2 or more bones meet

Question 2

Types of articulations

Answer 2

• synarthrodial
• amphiarthrodial
• diarthrodial

Question 3

Synarthrodial articulations

Answer 3

IMMOVABLE jts or places were 2 bones FUSE together

Ex. sutures btwn plates of skull

Question 4

Foramen magnum

Answer 4

big hole where spinal cord comes out

Question 5

Amphiarthrodial articulations

Answer 5

Cartilaginous jts connected via fibrocartilage that is flexible
- allows only a SMALL ROM

Ex. intervertebral discs btwn vertebrae

Question 6

Diarthrodial articulations

Answer 6

allow most FORCEFUL motions and GREATEST ROM

Held together by ligaments and moved via tendons

Has articular cartilage, synovial fluid and jt. capsule

Ex. knees, hips, elbows

Question 7

Ligaments vs tendons

Answer 7

Ligaments join bone to bone
Tendons join muscle to bone

BOTH can bear TENSION ONLY

Question 8

Articular cartilage

Answer 8

Part of diarthdorial jt.

covers bearing surfaces of bones
- LOW coefficient of friction
- slides nicely over other cartilage

Question 9

Synovial fluid

Answer 9

Part of diarthrodial jt.

Joint space is full of synovial fluid that LUBRICATES + NOURISHES the cartilage

Brings nutrients in and takes toxins/metabolites out

Question 10

Joint capsule

Answer 10

Part of diarthrodial jt.

Watertight enclosure on the jt. that keeps synovial fluid in

Question 11

Stress

Answer 11

Amount of LOAD in structure

Force/unit area

Question 12

Strain

Answer 12

Amount of LENGTHENING that occurs w/ the load

Question 13

Stress vs strain curve

Answer 13

Slope = STIFFNESS of the material

Tendon and ligament are stress stiffening = the more you pull, the stiffer they get (more resistance)

Tendon needs less strain to reach same amount of stress b/c tendon is stiffer

Ligaments put up less resistance to strain

Question 14

Ligaments and tendons and age

Answer 14

Ligaments and tendons become stiffer w/ age

Less ROM and greater chance of tearing/rupturing

Warming up makes them less stiff = more ROM and reduced risk of injury

Question 15

Stability of joint

Answer 15

How easy it is to disrupt or injure a jt

Less stability = easier to injure

Question 16

Factors that influence joint stability

Answer 16

1. Bony congruency (how well bones fit together)
   - ex. elbow
2. Tightness and strength of ligaments
   - ex. hand
3. Strength and angles of muscle attachment
   - ex. shoulder

1) is the best –> 3 (least stable)

Question 17

Muscles that stabilize the shoulder

Answer 17

Pull from lateral to medial (pulling humerus inwards b/c glenoid fossa is shallow)

Question 18

Mobility

Answer 18

How far a jt. can translate and rotate

More mobility = less stability

Question 19

End feel of joints

Answer 19

1. bone-to-bone
2. soft-tissue approximation
3. tissue-stretch

Question 20

Bone-to-bone end feel

Answer 20

HARD, UNYIELDING
- not painful

Ex. elbow extension (olecranon locks into fossa); dorsiflexion of ankle

Question 21

Soft-tissue approximation end feel

Answer 21

slightly MUSHY feel as soft tissues are compressed
- slight yield w/ overpressure

Ex. elbow flexion

Question 22

Tissue stretch end feel

Answer 22

‘SPRINGY’ feel as soft tissues are stretched
- slight yield to overpressure (much LESS than soft tissue)

Ex. shoulder elevation over head

Question 23

Frame of reference

Answer 23

attached to part of the system (segment-fixed) or to the ground (lab-fixed or global system)

Muts be composed of 1 origin and 3 axes

Question 24

Linear translation

Answer 24

distance along each of the frame axes

Question 25

Angular rotation

Answer 25

rotation about each of the frame axes

One of references axes must line up with jt. axis