Chapter 38 Tissues of the Musculoskeletal System

Question 1

Collagen arrangement in tendons

Answer 1

Parallel arrangement of their collagen since they’re subject primarily to tensile loads

Question 2

What are the 4 cartilage zones

Answer 2

First 3 zones are unmineralized 4th is calcified

Zone 1 - superficial or tangential zone
Zone 2 - transitional zone
Zone 3 - Radiate zone
Zone 4 - Calcified zone

Question 3

Describe zone 1 in cartilage

Answer 3

Superficial or tangential zone
Highest cell density
Small and flat and oriented parallel to the surface
Withstands tension on the articular surface

Question 4

Describe zone 2 in cartilage
what forces can it withstand?

Answer 4

Transitional zone
Larger and rounder cells
Withstands shear and compression

Question 5

What type of collagen is in articular cartilage

Answer 5

85-90% of articular cartilage is type II collagen (small amount of VI, IX, XI, XII, XIV)

Question 6

What occurs during cartilage damage?
Reversible?
Predominant material after injury?

Answer 6

Following loss of proteoglycan from cartilage matrix, proteoglycan can be largely restored by de novo biosynthesis
Marked loss can be irreversible leading to joint degeneration
Fibrocartilage is the predominant material that forms following vascularization of naturally occurring or iatrogenic full-thickness articular cartilage defects.

Question 7

What produces glycosaminoglycans

Answer 7

Chondrocytes, fibroblasts, and synoviocytes

Question 8

What are the two major classes of glycosaminoglycans and an example of each

Answer 8

Glucosaminoglycans - hyaluronic acid
Galactosaminoglycans - chondroitin sulfate

Question 9

What are the three types of tendons

Answer 9

Aponeuroses
Positional tendons
energy storing tendons

Question 10

What type collagen is in tendons

Answer 10

Mostly type I

Question 11

What is the function of tendons

Answer 11

transfer the force of muscular contraction to the skeleton

Question 12

Describe aponeuroses tendons and give examples

Answer 12

They are flattened structures that connect muscles to bones or to other fascial elements or that form connective tissue leaves within the substance of a pennate muscle*
Pennate muscles have muscle fibers attaching diagonally to a central tendon i.e. rectus abdominis muscle or fascia of the bicep femoris

Question 13

Describe positional tendons and give examples

Answer 13

Discrete and relatively stiff structures that transfer muscular forces to bones in such a manner to cause joint motion i.e. infraspinatus muscle tendon

Question 14

Describe energy-storing tendons and give examples

Answer 14

Greater elastic fiber content responds to forces by energy storage and elastic recoil i.e. common calcaneal tendon

Question 15

What are the types of ligaments and what type of collagen do they have

Answer 15

Capsular ligament and intra-articular ligament
Mostly type I collagen

Question 16

Describe ligaments

Answer 16

Connective tissue bands that attach to bones. Typically span a joint.
Can have two attachments to the same bone (i.e. transverse humeral ligament)

Question 17

Describe sharpeys fibers and their relationship with enthesis

Answer 17

They are dense bands of collagen that merge with the periosteal membrane and penetrate deeply into cortical bone.
Periosteum is bound to bone by bundles of collagen fibers known as Sharpey’s fibers
Enthesis: specialized regions of a tendon or ligament at sites of insertion or attachment to bone.
Fibrous entheses are made up of Sharpey’s fibers

Question 18

Role of calcium in skeletal muscles

Answer 18

Responsible for muscle contraction
Ach from axon travels through t-tubule causes interaction between dihydropyridine receptor and ryonadine receptor. Ca2+ flow out into the cell from sarcoplasmic reticulum. Ca binds to troponin causing tropomyosin to move out of the way and myosin heads can bind to actin and cause muscle contraction.

Question 19

What are type 1 muscle fibers

Answer 19

Slow twitch muscle fibers are rich in mitochondria
Can sustain contraction of low velocity and low force

Question 20

What are type 2 muscle fibers

Answer 20

Fast twitch muscle fibers that are rich in myofibrils*
adapted to perform transient, high velocity and high force contractions