Could someone describe the structure of a skeletal muscle and skeletal muscle fiber to me, Please?

Question

I need to understand this. My text book explains it to me, but it just doesn't click. Could someone put this into thier own words, so that you can help me to understand this better??
Thankyou for your help. It is very much appreciated.

Answer 1

a skeletal muscle is one of the 3 types of muscle. it's nucleus is peripherally located and since it is long (fiber) and a fusion of its embryonic myoloblasts, it is multinucleated.

A skeletal muscles primary function is for voluntary, quick and intense muscle actions so has striations. but before we go to that...the whole muscle (e.g. pectoralis, rectus abdominis etc.) is often enclosed in connective tissue to make the muscle action more efficient (maybe you have read about single and multiple innervations?). the connective tissue that encloses the whole muscle is called the Epimysium. Each epimysium is composed of muscle fascicles. the connective tissue surrounding these muscle fascicles is called the perimysium. and the muscle fibers composing each muscle fascicle is enclosed by the endomysium.

http://training.seer.cancer.gov/module_anatomy/images/illu_muscle_structure.jpg

now we go the structure that makes is so abundant in a skeletal muscle. It's sarcomere.

in a sarcomere you have both thin and thick filaments (lateral thin filaments and medial thick filament in a sarcomere ).

the thin filament is made up of actin, troponin and tropomyosin. remember you double helix structure? it's somewhat like that. the actin filaments twist. then around it still in a helical like manner are the troponin and tropomysin. if i remember correctly i think there are 7 actin units for every single troponin and tropomyosin.

your medial thick filament is made up of myosin with myosin heads at either side (up and down to connect with you thin filament during muscle contraction).

the thin and thick filaments were at the molecular level. at a ocular level or what appears in our microscope...we see bands...if i am correct this is what confused you?

http://www.sport-fitness-advisor.com/images/sarcomere.jpg

the Z line is where your thin filaments attach. The M line is where your thick filaments attach. your I band is the region where your thin filament does not overlap with your thick filaments (the region becomes smaller during muscle contraction). While your A band is your thick filament region. Your H band/zone is the region where your thick filament does not overlap with your thin filament.

Answer 2

Try this .... diagrams + explanation

http://en.wikipedia.org/wiki/Skeletal_muscle