Chapter 38 Tissues of the Musculoskeletal System Flashcards
Collagen arrangement in tendons
Parallel arrangement of their collagen since they’re subject primarily to tensile loads
What are the 4 cartilage zones
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
Describe zone 1 in cartilage
Superficial or tangential zone
Highest cell density
Small and flat and oriented parallel to the surface
Withstands tension on the articular surface
Describe zone 2 in cartilage
what forces can it withstand?
Transitional zone
Larger and rounder cells
Withstands shear and compression
What type of collagen is in articular cartilage
85-90% of articular cartilage is type II collagen (small amount of VI, IX, XI, XII, XIV)
What occurs during cartilage damage?
Reversible?
Predominant material after injury?
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.
What produces glycosaminoglycans
Chondrocytes, fibroblasts, and synoviocytes
What are the two major classes of glycosaminoglycans and an example of each
Glucosaminoglycans - hyaluronic acid
Galactosaminoglycans - chondroitin sulfate
What are the three types of tendons
Aponeuroses
Positional tendons
energy storing tendons
What type collagen is in tendons
Mostly type I
What is the function of tendons
transfer the force of muscular contraction to the skeleton
Describe aponeuroses tendons and give examples
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
Describe positional tendons and give examples
Discrete and relatively stiff structures that transfer muscular forces to bones in such a manner to cause joint motion i.e. infraspinatus muscle tendon
Describe energy-storing tendons and give examples
Greater elastic fiber content responds to forces by energy storage and elastic recoil i.e. common calcaneal tendon
What are the types of ligaments and what type of collagen do they have
Capsular ligament and intra-articular ligament
Mostly type I collagen
Describe ligaments
Connective tissue bands that attach to bones. Typically span a joint.
Can have two attachments to the same bone (i.e. transverse humeral ligament)
Describe sharpeys fibers and their relationship with enthesis
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
Role of calcium in skeletal muscles
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.
What are type 1 muscle fibers
Slow twitch muscle fibers are rich in mitochondria
Can sustain contraction of low velocity and low force
What are type 2 muscle fibers
Fast twitch muscle fibers that are rich in myofibrils*
adapted to perform transient, high velocity and high force contractions
