Muscoskeletal 4: Muscle 1 Flashcards
List the functions of muscle
- Movement : movement of bones, transport of gut content, lymph transport (smooth), circulating blood (cardiac)
- Stability : stabilising joints with wide range of movement through active contraction (instead of ligaments articular capsule). + maintaining posture
- Communication: facial expression, body language, writing, speech
- Control of body openings and passages: sphincters in pupil, mouth (entry) + urethral, anal (smooth + skeletal) for exit
- Heat production: produces 85% of body heat which maintains body at 37 degrees for normal function
Compare the terms Origin, Insertion, Osteotendinous junction, Myotendinous junction, tendon and muscle belly to describe the general anatomy of skeletal muscle
The muscle belly is the organ which attaches to the bone by tendons.
The attachment that moves the least during muscle contraction is the origin (us.axial) whereas the attachment that moves the most during muscle contraction is the insertion (us. append)
On the two sides of the tendon are osteotendinous junction to the bone and myotendinous junction to the muscle. OTJ is much stronger (sharpeys fibres) than MTJ.
List the order of layers of skeletal muscle from Epimysium to myofibril
Epimysium, perimysium, fascicle, endomysium, myocyte, sarcolemma, sarcoplasm, myofibril
Describe the features of a myocyte - what makes it up
Multinucleated, has a sarcolemma that conducts AP well for uniform contraction. It has a sarcoplasm containing lipids, glycogen and myoglobin (O2 store) and many myofibrils
Describe the structure of a myofibril
They are made of contracting units called sarcomeres.
which are divided by Z discs
Describe the structure of a sarcomere
Dark A band in the middle and Light I bands on the outside. Z discs separate the I bands into half.
Describe the structure of Fascicle
A bundle of myocytes surrounded by endomysium: Loose irregular CT. With a basement membrane in between the sarcolemma and endomysium (secreted by both).
This contains lots or nerves and capillaries that supply the myocytes.
Describe the structure of muscle (organ)
A bundle of fascicles that are surrounded by perimysium (dense irregular). Then layer of epimysium that surrounds the perimysium, getting coarser and stronger as you get to the outside border of muscle.
Compare the CT of skeletal muscle and how are they arranged in muscle in to out
endo: loose irregular
peri + epi: dense irregular
Arranged in to out : endo, peri, epi but all blended together.
Where is the deep fascia found
It underlies the skin and subcutaneous tissue called superficial fascia.
It covers the epimysium of muscle but allows it to glide underneath,
- around bones it can blend with the periosteum or
-can be part of muscle tendon as an attachment for muscle.
Function of deep fascia
Often, it separates muscles with similar action or supplied with same nerves / bv into compartments by making these walls of deep fascia.
What is investing fascia
Deep fascia that are deeper walls or septa- a continuation of the lining that goes between muscles (intermuscular septa) or bones (interosseous membrane). Where investing fascia comes into contact with bone it fuses with the periosteum.
Compare hyperplasia vs hypertrophy.
Hyperplasia: when tissue/organ increases in size due to an increase of cell number. (skeletal muscle can’t)
Hypertrophy: increase in size due to increase in cell size but not
# of cells. This is due to increases in size of individual myocytes by increasing number of myofibrils.
What stimulates hypertrophy
Heavy resistance training - use to maximum fatigue and use of anabolic steroids.
How do anabolic steroids increase size of muscle
Anabolic steroids are variants of testosterone that overstimulate skeletal muscle and bone to increase protein synthesis. But it has other side effects like 2nd puberty.
