S&F of muscular and fascial systems Flashcards
Approximately how many muscles are there in the human body, and how much body weight do they comprise of
There are approximately 680 muscles in the human body, that comprise 40-50% of an individual’s body weight
What are the 3 types of muscle tissue and what is their role
Smooth - muscles found in various internal organs (e.g. blood vessels)
Cardiac - heart muscles
Skeletal - muscles that cause joint movement
What is the main function of skeletal muscles
Skeletal muscles cause joint movement, or the muscle contractions produce the force that cause joint movement
What are some other functions of skeletal muscles
Protection to underlying structures
Function as a shock absorber
Provide dynamic stability to joints
Maintain posture and provide support
Produce a major portion of total body heat
3 characteristics of skeletal muscles
Extensibility
Elasticity
Contractility - the ability to develop tension (force) when stimulated
Sarcolemma
A thin transparent extensible cell (plasma) membrane that covers each
muscle fibre
Epimysium
It is a layer of dense irregular connective tissue which surrounds the entire muscle and protects muscles from friction against other muscles and bones.
Endomysium
A thin sleeve of fibrous connective tissue that encloses the individual muscle
fibers and connects muscle fibers to one another
i.e. between fibres
Perimysium
Perimysium is a sheath of dense irregular connective tissue that groups muscle fibres into bundles or fascicles.
How is the structure of the skeletal muscle organised
The muscle belly is made up of muscle fascicles. Between these is the perimysium.
In each muscle fascicle are many muscle fibres. The endomysium connects these muscle fibres
A single muscle fibre contains a sarcolemma, which has many myofibrils
List the key aspects of a skeletal muscle
Epimysium
Fascicles
Endomysium
Perimysium
Muscle fibre
Sarcolemma
Myofibril
Sarcomere
The segment between the neighbouring Z-lines. This is the basic contractile unit of the muscle
Z band
Defines the boundary between 2 sarcomeres in a muscle fibre
Sarcomeres are located between the _________ along the length of a _________
Sarcomeres are located between the Z lines along the length of a myofibril
Each sarcomere contains
I bands
A bands
H zone
M line
I bands
I bands - light band located at each end of a sarcomeres length - contains only actin (I is a thin letter I bands only contain thin actin filaments)
A bands
A bands - dark band in the mid point of the sarcomere - contains the full lengths of the myosin filaments and the regions where myosin and actin overlap
A band - ALL of the myosin
H zone
The lighter area within the A-bans, consists of only myosin (no overlap with actin)
M line
The M line within the H zone is the area where adjacent myosin filaments attach to one another
Tendons:
Where are they located?
What do they do?
What are they composed of?
Tendons are located at either end of the muscle belly
Most tendons attach muscle to bone, some attach muscle to other tendons, fascia, ligaments or skin
Tendons are composed of dense fibrous connective tissue that is cordlike in appearance
Tendon sheath
Where tendons cross bony areas, they are covered with a tendon sheath to protect them from wear and tear from bony structures they cross. It functions to reduce friction between the tendons and bony structures they cross
Function of tendons
Transmit the force generated by contracting muscles to bones
Origin and insertion of tendons
Origin - proximal attachment of a muscle or the part that attaches closest to the midline or centre of the body
Insertion - distal attachment of a muscle or the part that attaches farthest from the midline or centre of the body
What can muscle contractions be defined according to?
Whether there is a change in joint position associated with the muscle action. If there is a change in joint
position, the muscle action can be further defined by whether the muscle creating
tension is shortening or elongating.
Isometric contraction
Tension is developed within the muscle, but there is no change in joint position
Isotonic contraction
Tension is causing a change in joint position, or controlling a change
in joint position (concentric or eccentric)
Concentric contraction
The muscle tension is causing a change in joint position
During concentric muscle actions, the muscle producing the tension
shortens
Fixator
Muscles that act during the movement or portion/phase of the movement to
hold/fixate/stabilize a bone while a prime mover performs its function (e.g.
During a biceps curl, muscles acting on the scapula and glenohumeral joint
stabilize the shoulder complex and humerus so the biceps brachii can more
effectively perform the bicep curl exercise
Dense connective tissue
A continuous sheet of fibrous membrane located beneath the skin and around muscles and organs
Superficial fasica
Immediately deep to the skin, covers the entire body
