Histology - Muscle

sarcomere

basic contractile unit of a muscle

myoblast

embryonic precursor cell

myofibril

the cable, group of muscle myofilaments, create the stippled pattern inside striated muscle when viewed in transverse profile

myofilaments

two kinds of wires, think filaments (myosin) and thin filaments (actin), create light and dark banding in striated muscle

skeletal muscle

voluntary, striated, peripheral nuclei, multinucleated

myocyte

single cell formed by fusion of multiple myoblasts during embryonic development, elongated and tubular morphology, surrounded by fine connective tissue filled with capillaries

myofibril

contractile elements of the myocyte are organized bundles of myofilaments, form dots or stippling

thin filament

composed of actin, tropomyosin, and troponin

sarcomere

structural and contractile unit of muscle, spans distance between two adjacent z lines, created by the repetitive arrangement of myofilaments within the myofibril

z line

where thing filaments are anchored, in the middle of the light I band

A band

stands for anisotropic, thick and thin filaments overlap

I band

stands for isotropic, only thin filaments are present in the lighter I band

cardiac muscle

involuntary, striated, centralized nuclei, restricted to heart and initial portions of associated arteries and veins, cells bifurcate to connect to more than one neighboring cell creating a branching pattern

intercalating discs

dark transverse bands scattered through cardiac muscle, site of communication and adhesion between connecting muscle cells,

purkinje fibers

myoconducting fibers, modified cardiac muscle fibers that are larger and paler in staining, conduct nerve impulses within the ventricular myocardium

smooth muscle

involuntary, non-striated, central nuclei, located throughout the body wherever involuntary motion occurs, nuclei are elongated and fusiform

endomysium

fine CT filled with capillaries and surrounds each myocyte

perimysium

denser CT that surrounds fascicles

epimysium

most dense CT that surrounds the outer surface of a muscle, referred to as deep fascia

tendons

attach muscle to bone

ligaments

attach bone to bone

enthesis

site of attachment of tendon, ligament, fascia, aponeurosis, and joint capsule of bone

fibrous enthesis

when tendon attaches to metaphysis or diaphysis

fibrocartilagenous enthesis

when tendon attaches to epiphysis of long bone of to bones of manus and pes

perforating fibers

sharpeys fibers, collagen fibers from a tendon or ligament that anchor the muscle into bone