The Musculoskeletal System Flashcards
What are the 4 types of fundamental tissues?
- Epithelial
- Connective
- Muscle
- Nervous
Connective tissue is composed of what 2 substances?
- ground substance
- fibroblasts
What 3 things do fibroblasts produce?
- collagen
- elastin
- reticulin fibers
2 types of collagen
loose or dense
Where can loose collagen be found?
In capsules, muscles, nerves, fascia, and skin
What is the main function of loose collagen?
Provides structural support
Where can dense collagen be found?
Ligaments, tendons, bones, and aponeuroses
What is the function of fascia?
It provides an interconnection between tendons, ligaments, capsules, nerves and the intrinsic components of muscle
What is the function of tendons?
To attach muscle to bone at each end of the muscle, and, when stretched, store elastic energy that contributes to movement
What are the 3 main sections of a tendon?
- Bone-tendon junction
- Tendon mid-substance
- Musculotendinous Junction (MTJ)
The point where the collagen fibers of the tendon directly insert into the bone is called what?
Enthesis
What is the role of the enthesis?
To absorb and distribute the stress concentration that occurs at the junction over a broader area
What type of injuries are likely to occur at the tendon’s midsubstance?
oversue injuries
What type of injuries are likely to occur at the tendon’s MTJ?
tensile failure (sudden)
What do ligaments do?
attach bone to bone
How do ligaments contribute to the stability of function?
By preventing excessive motion, guide the direction of movement, provide proprioceptive feedback, and act as the attach point to the joint capsule
What parts of ligaments are the most avascular and have minimal innervation?
The middle sections
Do tendons or ligaments deform less under an applied load and are able to transmit the load to bone?
Tendons
Do tendons or ligaments have a more unidirectional line of pull?
tendons
Ligaments still provide stiffness however
3 forms of cartilage
- hyaline
- elastic
- fibrocartilage
Where can hyaline (articular) cartilage be found?
covering bones which provides an almost frictionless motion between joint surfaces
What 3 things is hyaline cartilage composed of?
- chondrocytes
- water
- ECM
Does hyaline cartilage have blood vessels, lymphatics, and nerves?
NO
What are the 4 zones of articular cartilage?
1) Superficial zone
2) Middle zone
3) Deep zone
4) Tidemark zone
What is the function of the superficial zone of articular cartilage?
to protect the deeper layers from sheer stress
What is the function of the middle zone of articular cartilage?
provides an anatomic and functional bridge between the superficial and deep zones
How are collagen fibers oriented in the middle zone?
obliquely
What is the function of the deep zone of articular cartilage?
Provides the greatest resistance to compressive forces
How are collagen fibers oriented in the deep zone?
radially
What is the function of the tidemark zone of articular cartilage?
prevents diffusion of nutrients from the bone tissue to the cartilage
Where can elastic cartilage be found?
the outer ear, larynx, etc.
What is the function of fibrocartilage?
A shock-absorber in both weight-bearing and non-weight-bearing joints
fibrocartilage’s large fiber content, reinforced with numerous collagen fibers, makes it ideal for what?
Bearing large stress in all directions
What are a few examples of fibrocartilage?
The pubic symphysis, IVDs, and the menisci of the knee
5 functions of bone
- provide support
- enhance leverage
- protect vital structures
- provide attachments for both tendons & ligaments
- store minerals
What are the 4 characteristics of skeletal muscle?
- Excitability
- Elasticity
- Extensibility
- Contractility
Excitability is the ability to do what?
respond to stimulation from the nervous system
Elasticity is the ability to do what?
change in length or stretch and return to normal length afterwards
Extensibility is the ability to do what?
shorten and return to normal length
Contractility is the ability to do what?
shorten and contract in response to some neural command
The tension developed in in skeletal muscle can occur _____ (stretch) or ____ (contraction)
passively
actively
A single muscle cell is called what?
a myofiber
Describe the 3 coverings of myofibers
A single myofiber is wrapped in endomysium.
Bundles of myofibers are wrapped in perimysium
Bundles of myofibrils are wrapped in epimysium
Each myofiber consists of thousands of fibers called ______ which run parallel to the myofibril axis.
myofilaments
Myofilaments are composed of what 2 proteins?
actin and myosin
Structures called ______ serve to connect the actin and myosin filaments
cross-bridges
During contraction the cross-bridges _____.
During relaxation the cross-bridges _____.
attach
detach
What 2 proteins found in the actin filaments regulate the attachment and detachment of the cross-bridges?
tropomyosin and troponin
Each muscle fiber is innervated by what type of neuron?
a somatic motor neuron
What constitutes a motor unit?
One neuron and its corresponding muscle fibers
What are the 2 major types of muscle fiber?
- Type I (slow twitch)
- Type II (fast twitch)
Which type of muscle fiber is the first to be recruited?
Type I
Define prime agonist
the muscle that is directly responsible for producing movement
Define synergist
the muscle that performs cooperative muscle function with regard to agonist
Define stabilizer
The muscle that contracts statically to steady or support some part of the body
Define neutralizers
muscles that act to prevent an undesired action
Define antagonists
muscles that have effect opposite of the agonist
3 types of contractions
- Isometric
- Concentric
- Eccentric
As the speed of a concentric contraction increases, the force produced _____.
decreases
As the speed of a eccentric contraction increases, the force produced _____.
increases
A slow eccentric contraction is similar to what type of contraction?
an isometric contraction
Under what 2 circumstances does a muscle generate the greatest amount of torque?
- When the line of pull is oriented at a 90 degree angle to the bone
- When it is attached anatomically as far from the joint center as possible
Skeletal muscle blood flow increases __-fold during muscle contraction
20
4 differences between respiratory and skeletal muscle
- Skeletal muscle overcomes inertial loads, whereas respiratory muscles overcome elastic and resistive loads
- they are under voluntary and involuntary control
- they have to contract rhythmically and generate the required forces for ventilation throughout the entire life of an individual
- They are constrained to operate at a particular resting length
2 Joint classifications based on movement
Synarthrosis (little to no movement) or Diarthrosis (free bone movement and great mobility)
2 major types of synarthroses
- Fibrous joints
- Cartilaginous joints
3 types of fibrous joints and an example for each
- suture –> skull
- gomphosis –> tooth/mandible
- syndesmosis –> tibfib/radioulnar
2 types of cartilaginous joints and an example for each
- Synchondrosis –> manubriosternal
Symphysis –> symphysis pubis
6 characteristics of diathroses
- joint cavity
- articular cartilage
- synovial fluid
- synovial membrane
- fibroelastic capsule
- mechanoreceptors and nociceptors
Example of a spheroid joint
shoulder (ball and socket)
Example of a trochoid joint
atlantoaxial joint (pivot)
Example of a condyloid joint
wrist
Example of a ginglymoid joint
humeroulnar (hinge)
Example of an ellipsoid joint
radiocarpal
Example of a planar joint
intermetatarsal
Example of a sellar joint
thumb (saddle)
What type of fluid is necessary to minimize the frictional resistance between weight-bearing surfaces in joints?
synovial fluid
What are bursae?
Flattened, saclike structures that are lined with synovial membrane and filled with synovial fluid, which allows for smooth motion between muscles, tendon, ligament, and bones
What are the 2 types of movement?
- translation which occurs in either a straight or curved line
- rotation which involves a circular motion around a pivot point
A joint that can swing in one direction or can only spin is said to have ___ DOF
one
A joint that can swing and spin in one way or can swing in two completely distinct ways, but not spin is said to have ___ DOF
two
A joint that can spin and also swing in two distinct ways is said to have ___ DOF
three
What is kinematics?
They study of motion
What is kinetics?
The term applied to the forces acting on the body
3 types of arthrokinematics
roll, slide, and spin
Convex surface moving on concave surface, then the slide will be in the _____ direction to the osteokinematic motion
opposite
Concave surface moving on convex surface, then the slide will be in the _____ direction to the osteokinematic motion
same
What are levers?
rotations of a rigid surface around an axis
When does a first-class lever occur?
When two forces are applied on either side of an exis and the fulcrum lies between the effort and the load (like a seesaw)
Examples of a first-class lever
contraction of the triceps at the elbow o tipping the head forwards and backwards
When does a second-class lever occur?
When the load (resistance) is applied between the fulcrum and the point where the effort is exerted
Example of a second-class lever
Weight bearing plantarflexion
When does a third-class lever occur?
When the load is located at the end of the load (like a drawbridge or crane)
Example of a third-class lever
Elbow flexion
Most movable joints function as what type of lever?
third-class
In a closed kinematic chain the ____ segment is stabilized and the movement is at the _____ segment
distal
proximal
In an open kinematic chain the ____ segment is stabilized and the movement is at the _____ segment
proximal
distal
