Download Upper body

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Early gross anatomists viewed the muscled with just the naked eye. Then, with the
use of microscopes we used histology to classify muscles by saying what the cells
looked like under the microscope. Striated muscle cells looks segmented (striated)
with light and dark segments. Smooth muscle has no striations and is smooth.
Branch-striated muscle is criss-crossed in a network pattern with striations that are
irregular. Nerve control is important in activating the muscle. Involuntary means we
have no control over it, whereas voluntary we do have control. Can some muscles be
involuntary and voluntary?? Think respiratory muscles.
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**Make a table with 3 columns labeled as Location, Appearance, and Nerve Control.
Then list the characteristics for skeletal, visceral, and cardiac muscle.**
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Fusiform—run longitudinally
Quadrate—4 distinct sides of the muscle belly
Triangular—shaped as a triangle
Pennate (uni, bi…)—a central tendon with fibers coming off at an angle; unipennate
is only on 1 side, whereas bipennate has it on both sides and looks just like a feather
Pennate muscles have many more fibers than parallel arranged fibers because of the
way it is organized. This allows pennate to be more powerful. Pennate muscle fibers
amplify force; fusiform amplifies speed of contraction and range of motion (ROM).
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Shape—ex: quadratus lumborum
Size—ex: brevis, magnus
Action—ex: supinator does supination
Location—ex: tibialis anterior (anterior of tibia)
Attachments—ex: biceps (2), triceps (3)
Direction of fibers—ex: longus
Number of divisions within the muscle—ex: triceps
So by looking at the name of the muscle, it can give you clues as to where it is
located, what is does, etc.
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ability to shorten or contract
Extensibility—ability to stretch
Elasticity—ability to return to resting length
Tonicity—firmness or hardness (tone)
Excitability—responds to stimuli
Contractibility—
All muscles have these behavioral properties. Tendons do not, however. Tendons are
NOT contractile.
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muscle shortens and causes
movement
Isometric—prevented from shortening
Isotonic—
Once again there is an anatomical classification for how muscle contracts, however,
we are more concerned with the movement. So we will be using the Kinesiological
classification terminology.
muscle shortens
Static (Isometric)—no change in joint angle
Eccentric—muscle lengthens
Concentric (Isotonic)—
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This is a basic understanding of the anatomy of the muscle. We are not going to go in
depth in it for this class, but you will need to know these basic facts. The epimysium
is the outer covering and surrounds the entire muscle, holding it together. The
perimysium is the connective tissue sheath that surrounds each bundle of muscle
fibers. The endomysium surrounds each individual muscle fiber.
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You will need to know this basic anatomy of a sarcomere. A sarcomere is the basic
functional unit of skeletal muscle and is made up of different proteins (actin is the
thin protein and myosin is the thick protein) and regions. 1 sarcomere goes from Z
line to Z line. In the picture you can see the A band—the A band is the area where
both proteins (actin & myosin) overlap each other. The I bands are the areas where
only the actin protein is. The H zone is the middle of the A band visible only when
the muscle is relaxed, but when the muscle contracts the H zone disappears because
the actin and myosin slide on top of each other.
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Actin and myosin are the protein builders for muscle action and the contraction
process is powered by ATP (adenosine triphosphate). The Sliding Filament Theory
deals with the contraction process and is taught in depth in your exercise physiology
class. Remember a sarcomere goes from Z line to Z line and
sarcomere+sarcomere+… = a myofibril. During contraction the sarcomeres will
become shorter as the Z lines come closer together—just the sarcomere shortens,
not the proteins.
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SO = slow oxidative--slow twitch fibers which are used more for endurance since
they have a high resistance to fatigue (ex: marathon runners)
FOG = fast oxidative glycolytic—fast twitch fibers “a” that are used for short, high
intensity events such as the 400 meter event
FG = fast glycolytic—fast twitch fibers “b” that are used for all-out effort, highly
explosive events like the 50 yd dash, hammerthrow, etc.
Which fiber type do you think you have more of for the steeplechase?? The 100
meter??
Now you can’t increase the amount of muscle cells you have (differs genetically), but
you can increase the cell’s size which is called hypertrophy.
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Muscles on the anterior side of the vertebral column do head/neck flexion. Muscles
on the posterior side will do the opposite—extension. For the sternocleidomastoid
to do neck flexion, both sides have to contract. To do lateral flexion and rotation,
only 1 side contracts. Now it is able to rotate to the opposite side when 1 side
contracts because the muscle fibers have a downward, medial orientation. Try and
visualize if both sides contract that neck flexion occurs. Now try and visualize if 1 side
shortens. What happens??
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In the Scalenes group there is an anterior, medius, and a posterior, but we are going
to group them all together. The Scalenes also act as a synergist muscle for
respiration, which we will go over later. For these muscles you just need to know the
action and general region where they are located, not specific origin and insertions.
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These are muscles on the posterior side of the vertebral column so they do extension
of the head/neck. Once again for the splenius capitus and splenius cervicis, to obtain
extension both sides have to contract and only 1 side has to contract to do the lateral
flexion and rotation.
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