MYOLOGY

I.   INTRODUCTION

3 kinds of muscle:

1.

2.

3.

II.  GROSS ANATOMY OF SKELETAL MUSCLE
A.  Introduction

-- made up of muscle fibers
* muscle cell = muscle fiber

-- Each skeletal muscle is an organ

-- tendons

* dense regular CT
* aponeuroses

B.  Connective Tissue Wrappings Around Muscle

-- muscle fiber wrapped in endomysium

-- groups of muscle fibers: fascicles   

 
-- fascicle is surrounded by perimysium

-- entire muscle surrounded by epimysium

-- surrounding all the CT wrappings is deep fascia

-- superficial fascia

III. MICROSCOPIC ANATOMY OF SKELETAL MUSCLE
A.  General Microscopic Structure

-- Muscle cell membrane: sarcolemma (sarco = flesh)

-- cytoplasm: sarcoplasm

-- it has cell organelles like lysosomes, ribosomes, and endoplasmic reticulum (called sarcoplasmic reticulum)

–  transverse tubules (T-tubules)

*  function:

-- each muscle fiber primarily composed of myofibrils

-- myofibril composed of myofilaments
* protein filaments

* thick myofilaments (thick filaments): myosin
* thin myofilaments (thin filaments): actin

B.  Banding Pattern (Striation Pattern)

1) light bands: I bands (I - LIGHT)
* thin myofilaments only

2) dark bands: A bands (A = DARK)
* thick and thin myofilaments

3) Z disc (Z line): dark structure in the middle of an I band

4) H zone (H band): a lighter, central region in the middle of A band

5) M line: dark line in middle of H zone

-- sarcomere - runs from Z disc to Z disc (functional contractile unit)

IV.  CONTRACTION OF SKELETAL MUSCLE
A.  Sliding Filament Model of Contraction

-- thick and thin myofilaments slide over one another
* length of each sarcomere shortens, muscle contracts

Changes to sarcomere during contraction:

1. H zone

2.I band

3.Z discs

4.

Thin myofilaments attach to a structure called the:

1. I band
2.  
3. Z disc
4.  
5. M line
6.  
7. H zone
8.  
9. A band

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