Biology 161 Topic 14: Muscular Structure

Skeletal Muscle Tissue

voluntary, striated, multinucleate

attached to bone or fascia(connective tissue)

cardiac muscle tissue

involuntary, striated, mononucleate

auto rhythmic(cells can self-regulate contraction)

smooth muscle tissue

involuntary, non-striated, mononucleate

excitability

respond to chemicals released from motor neurons 

conductivity

ability to propagate electrical signals over membrane

contractibility

ability to shorten and generate force

extensibility

ability to be stretched without damaging the tissue

elasticity 

ability to return to original shape after being stretched 

muscle

formed by a group of fascicles

fascicle

formed by a group of muscle fibers

muscle fibers

formed by a group of myofibrils

myofibrils 

contains bundles of protein filaments, organized into sarcomeres

connective tissue

• protects muscle cells

• reduces friction

• creates sec for extracellular fluid

epimysium

covers the entire muscle

perimysium

covers fascicles

endomysium 

covers muscle fibers 

muscle connection —> muscle to bone(indirect) 

collagen fibers of epimysium form strong fibrous tendon(dense regular connective tissue) that merges into periosteum(outer covering of bone) 

• most common connection 

• ex. biceps brachii, gastrochemus(calf muscle) 

muscle connection —> muscle to muscle(direct, fleshy) 

collagen fibers of epimysium are directly continuous with perimysium 

• looks like muscle emerges directly from bone 

• ex. intercostal muscle(ribs) 

muscle connection—> muscle to fascia 

muscles insert to broad sheet of connective tissue called aponeurosis- similar in structure as a tendon, but broad and flat 

• ex. abdominal aponeurosis 

circular(orbicularis oris) 

fascicles from concentrally arranged around an opening

convergent( pectoralis major)

fascicles from a broad area coverage on a common attachment

parallel/fusiform

fascicles parallel to long axis of muscle(sartorius)

pennate(deltoid)

fascicles attach at an angle to a central tendon with longer muscle cells can contract further