SKELETAL MUSCLE
Histology of the Skeletal Muscle
I. Characteristics of Skeletal Muscle Fibers
A. Striated
B. Multinucleated
C. Contains numerous mitochondria
D. Presence of Transverse tubules / T-tubules
E. Sarcoplasmic Reticulum with Lateral sacs (
terminal cisterns)
Terminal Cisterns- stores Ca2+
F. Myofibrils within the cytoplasm (bundle of
protein filaments)
II. Physiological Anatomy of Skeletal Muscle
A. Sarcolemma - a Thin Membrane Enclosing
a Skeletal Muscle Fiber
consists of a true cell membrane, called
the plasma membrane, and an outer
coat made up of a thin layer of
polysaccharide material that contains
numerous thin collagen fibrils
B. Myofibrils - composed of Actin and Myosin
Filaments
composed of about 1500 adjacent myosin filaments and 3000 actin filaments, which are large
polymerized protein molecules that are responsible for the actual muscle contraction
C. Titin Filamentous Molecules - keep the Myosin and Actin Filaments in place
side-by-side relationship between the myosin and actin filaments is maintained by a large number of
filamentous molecules of a protein called titin
Springy titin molecules act as a framework that holds the myosin and actin filaments in place so that the
contractile machinery of the sarcomere will work
D. Sarcoplasm- the Intracellular Fluid between Myofibrils
spaces between the myofibrils are filled with intracellular fluid called sarcoplasm, containing large
quantities of potassium, magnesium, and phosphate, plus multiple protein enzymes
Also present are tremendous numbers of mitochondria that lie parallel to the myofibrils.
mitochondria supply the contracting myofibrils with large amounts of energy in the form of
adenosine triphosphate (ATP) formed by the mitochondria.
E. Sarcoplasmic Reticulum - a Specialized Endoplasmic Reticulum of Skeletal Muscle
reticulum has a special organization that is extremely important in regulating calcium storage, release,
and reuptake and therefore muscle contraction
Handum_ 1|4
Histology of the Skeletal Muscle
I. Characteristics of Skeletal Muscle Fibers
A. Striated
B. Multinucleated
C. Contains numerous mitochondria
D. Presence of Transverse tubules / T-tubules
E. Sarcoplasmic Reticulum with Lateral sacs (
terminal cisterns)
Terminal Cisterns- stores Ca2+
F. Myofibrils within the cytoplasm (bundle of
protein filaments)
II. Physiological Anatomy of Skeletal Muscle
A. Sarcolemma - a Thin Membrane Enclosing
a Skeletal Muscle Fiber
consists of a true cell membrane, called
the plasma membrane, and an outer
coat made up of a thin layer of
polysaccharide material that contains
numerous thin collagen fibrils
B. Myofibrils - composed of Actin and Myosin
Filaments
composed of about 1500 adjacent myosin filaments and 3000 actin filaments, which are large
polymerized protein molecules that are responsible for the actual muscle contraction
C. Titin Filamentous Molecules - keep the Myosin and Actin Filaments in place
side-by-side relationship between the myosin and actin filaments is maintained by a large number of
filamentous molecules of a protein called titin
Springy titin molecules act as a framework that holds the myosin and actin filaments in place so that the
contractile machinery of the sarcomere will work
D. Sarcoplasm- the Intracellular Fluid between Myofibrils
spaces between the myofibrils are filled with intracellular fluid called sarcoplasm, containing large
quantities of potassium, magnesium, and phosphate, plus multiple protein enzymes
Also present are tremendous numbers of mitochondria that lie parallel to the myofibrils.
mitochondria supply the contracting myofibrils with large amounts of energy in the form of
adenosine triphosphate (ATP) formed by the mitochondria.
E. Sarcoplasmic Reticulum - a Specialized Endoplasmic Reticulum of Skeletal Muscle
reticulum has a special organization that is extremely important in regulating calcium storage, release,
and reuptake and therefore muscle contraction
Handum_ 1|4
