Ch 7 Muscular System Gross anatomy first! Pages

Muscles include: Cardiac Cardiac Smooth Smooth SKELETAL! This will be our focus for this test SKELETAL! This will be our focus for this test

Muscles contract, pulling one bone closer to another (typically they do not move equally in response to the contraction)

Anatomy of a muscle ORIGIN (head) –movement is minimal/stationary ORIGIN (head) –movement is minimal/stationary INSERTION – greatest movement INSERTION – greatest movement BELLY – fat middle portion BELLY – fat middle portion X

Often times: Origin is proximal to the insertion, especially in the limbs Origin is proximal to the insertion, especially in the limbs Insertion moves towards the origin Insertion moves towards the origin Most muscles are arranged in opposing pairs at joints Most muscles are arranged in opposing pairs at joints Roles of opposing pairs may change for different movements Roles of opposing pairs may change for different movements

Analogy: a screen door Spring attached to the doorframe = origin Spring attached to the doorframe = origin End attached to swinging door = insertion End attached to swinging door = insertion origin insertion LeversLevers diagramdiagram

Grouping Muscles AGONIST ANTAGONIST A muscle producing a certain movement A muscle acting in opposition to an agonist Group of muscles producing a certain movement = synergists If one from group plays a major role = prime mover Muscles that hold one bone in place while another bone is moved = fixators

Examples AGONIST(SYNERGISTS) ANTAGONISTS FLEXORS ABDUCTORSEXTENSORSADDUCTORS

There are seven methods of naming muscles (see handout) Direction Direction Size Size Shape Shape Action Action Location Location Origin and insertion Origin and insertion Number of origins Number of origins