Skeletal+Muscles

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=**__Skeletal Muscles__**= In order for the human body to enjoy a very wide range of movement, from the blink of an eye to running a marathon, the muscular system must come in to play, and taking center stage, the skeletal muscle.

Skeletal Muscle under a Microscope

**__Skeletal Muscles in the Body__**
The arrangement of body muscles permits them to either work together or in opposition of eachother to achieve the wide variety of movements. Muscles can only //pull//, never //push.// Most of the time, when a muscle shortens, its attachment to the moveable bone moves torward the orgin, or fixed immovable point of attachment.. This means that whatever one muscle or muscle groups does, there is another muscle or group that undoes the action.

**__[[image:bodies.jpg caption="Picture courtesy of dustinkierstead at flickr.com"]] Classification__**
Muscle can be classified into four functional group: prime movers, anagonists, synergists, and fixators.

**//Prime movers//**-
a muscle that provides the major force for producing a specific movement. For example, the biceps brachii muscle is a prime mover of elbow flexion.

**//Antagonists//**-
muscles that oppose or reverse a particular movement. When a prime move is active, the antagonist muscles are often stretched and relaxed. An example is the flexion of the forearm by the bicep of the arm is antagonized by the tricep.

**//Synergist//**-
help prime movers in two ways 1) add a little extra force to that same movement 2) reduce undesirable/unnecessary movement that might occur when prime mover contracts An example of this would be when the finger flexor muscles crothe bothe the writst and the phalanges, but you can still make a fist without bending your wrist.

**//Fixator//**-
when the synergists immobilize a bone or muscles orgin it is classified as a fixator. An example of this would be any muscle that help to maintain upright posture

**__Naming Skeletal Muscles__**
To name a skeletal muscle, it is based off of seven different criteria. 1) //**Location of a muscle**//- some muscle names indicate the bone or body region which the muscle is associated. Ex: the temporalis muscle overlies the temporal bone 2) //**Shape of muscle**//-some muscles are named for their shape. Ex: the right and left trapezius muscles form a trapezoid 3) //**Relative size of muscle**//- terms such as maximus (largest), minimus (smallest) longus(long) and brevis (short) are often used in muscle names Ex: gluteus maximus and gluteus minimus ( large and small gluteus muscles) 4) //**Direction of muscle fibers**-// the name of some muscles reveal the direction in which their fibers run in reference to an imaginary line somewhere in the middle of the body Ex: the rectuse femoris (straight muscle of the thigh) 5)//**Number of orgins**//- when biceps, triceps, or quadriceps form part of the muscles name it is assumed that the muscle has two, three, or four orgins Ex: biceps brachii muscle of the arm had two orgins, or heads 6)//**Location of the attachment**//- some muscles are named according to points of orgin. Ex: sternocleidomastoid muscle of the neck has a dual orgin on the sternum and clavicle and inserts on the mastoid process of the temporal bone 7) //**Action**//- muscles are named for the action they perform Ex: adductor longus brings about thigh adduction

There are over 600 muscles in the human body!! Picture courtesy of dozens from Flickr.com
 * __Major Skeletal Muscles of the Body__**