November 6 Lecture - November 6, 2008 Four Major Categories...

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November 6, 2008 Four Major Categories of Muscles - Based on principle functions carried out by muscles - When muscles contract, they are the result of multiple musculator movements (muscles will contract simultaneously) o Movement (motion) occurs due to many muscular movement at any point in time 1. Agonists (Prime (Primary) Movers) Muscles that are responsible 2. Antagonists Muscles must relax for motion to be achieved. Have opposite function from primary movers. Located in opposing locations from primary mover. Adds control and precision to the movement. (Similar to gas and break petal in car) 3. Fixator muscles Have a diversity of functions. Carry out the role of stabilizing a joint. Often involved in maintaining posture (or position). Ex. fixator muscles will contract at the same time as flexion muscles in the brachius (upper arm) that stabilizes the arm to the shoulder 4. Synergists Means “together.” Work together at the same time as the primary movers. Function is to complement the action of the primary movers, or stabilize structures so more effective movement can be achieved. Ex. Prevents rotation of bones so flexion can occur - Certain muscles can fit into multiple categories depending on the movement that is occurs o Very specific for certain regions of body and certain movements or motions that are being addressed Muscles of The Body Face, Scalp, and Neck Muscles - Muscles can be superficial (close to the skin) or deep (service the same regions of the body, further inwards) - Superficial muscles in this region are involved in creating facial expressions - Some of these muscles of origins in form of a tendon, while others are derived from a flat sheet of connective tissue known as an aponeurosis o Aponeuorosis: same function as tendon, large numbers of collagenous fibres - Muscles can also be connected directly to the periosteum of the bone - Muscles can originate from the skin itself o Contraction produces wide range of facial expressions - Muscles in this region are innerbated by the seventh cranial nerve, known as the facial nerve Muscles of the Scalp (Superficial muscles) - Entire portion of the scalp is covered by an aponeurosis, known as the epicranial aponeurosis (covers the outer surface of the cranium) o Flat sheet serves as the anchorage for most scalp muscles in the area
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- Three sets of muscles found in the scalp region, referred collectively as epicranius muscles o Frontalis muscles Arise from aponeuoris and extend down over the forehead and insert at the supraoribtal region (just about the eye) Raise the eye brows when contracted, to form regions in the skin of the forehead Ex. when you are surprised o Occipitalis muscles Located at the back of scalp Arise from occipital bone and insert in the posterior portion of the cranial aponeurosis Draw the skull backward or downward o Auricular muscles Three different slips: superior, posterior, and anterior Originate from aponeurosis and inserts onto the skin or cartilage of the
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This note was uploaded on 10/23/2011 for the course BIOL 2125 taught by Professor Dr.park during the Winter '02 term at A.T. Still University.

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November 6 Lecture - November 6, 2008 Four Major Categories...

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