MUSCULAR SYSTEM

• endomysium - muscle fiber is enclosed in a delicate connective tissue sheath
• perimysium - wrapped by a coarser fibrous membrane
• fascicle - bundle of fibers
• epimysium - covers the entire muscle
• tendon - indirectly attaches the muscle to bone, cartilage, or another connective tissue covering
• smooth muscle - no striation and is involuntary
• skeletal muscle - striated muscle and voluntary muscle
• cardiac muscle - striated, uninucleate and its control is involuntary
• intercalated discs - cardiac muscle fibers are branching cells joined by special gap junctions
• motor unit - consists of one neuron and all the skeletal muscle fibers it stimulates
• axon - threadlike extension of neuron
• axon terminal - forms junctions with the sarcolemma of a different muscle cell
• neuromuscular junction - contain synaptic vesicles and neurotransmitters
• acetylcholine - specific neurotransmitter that stimulates skeletal muscle fibers
• synaptic cleft - gap between two neurons, filled with interstitial fluid
• origin - attached to the immovable or less movable bone
• insertion - attached to the movable bone
• flexion - a movement, generally in sagittal plane, that decrease the angle of the joint and brings two bones closer together
• extension - opposite of flexion, a movement that increases the angle, or distance, between two bones or parts of the body
• hyperextension - extension that is greater than 180 degrees
• rotation - is movement of a bone around its longitudinal axis
• abduction - moving limb away from the midline of the body
• adduction - is the opposite of abduction, is movement of a limb toward the body midline
• circumduction - is a combination of flexion, extension, abduction and adduction commonly seen in ball-and-socket joints, such as in shoulders
• prime mover - major responsibility for causing a particular movement
• antagonists - muscles that oppose or reverse a movement
• synergists - help prime mover by producing same movement or by reducing undesirable movements
• fixators - specialized synergists
• frontalis - covers the frontal bone, runs the cranial aponeurosis to the skin of the eyebrow, where it inserts
• orbicularis oculi - fibers of the _ run in circles around the eye. allows you to close your eyes, squints, blink and wink
• orbicularis oris - the circular muscle of the lips. often called the "kissing" muscle
• buccinator - muscle runs horizontally across the check and inserts into the orbicularis oris
• zygomaticus - extends from the corner of the mouth to the cheekbone.

  "smiling" muscle
• masseter - runs from the zygomatic process of the temporal bone to the mandible, covers the angle of the lower jaw
• temporalis - fan-shaped muscle overlying the temporal bone
• neck muscles - move the head and shoulder girdle , small straplike
• platysma - single sheetlike muscle that covers the anterolateral neck
• sternocleidomastoid - are two-headed muscle, one found on each side of the neck
• pectoralis major - large fan-shaped muscle covering the upper part of the chest
• intercostal muscle - are deep muscle found between the ribs