muscular system part 1
TRANSCRIPT
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MuscularSystemOrigin - Point of attachment which is
more proximal and more fixed Insertion - The more distal and more
movable (flexible) point of attachment
Belly - Fleshy or middle part of a
muscle
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TypesofMuscles
Flexors - bend or flex a part
Extensor - straighten of extend a
part
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Abductors - pull a part away from the
median line or axis of the body
Adductors - Pull a part toward the
median line of the body
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Synergist - muscles that help the prime mover by producing the
same movement or reducing undesirable or unnecessary movement
ex. Sternoradialis – synergist of Biceps brachii Antagonist - muscle working in opposition to another muscle
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Naming of Skeletal Muscles 1. Location and direction of muscle fibers ex External Oblique Rectus abdominis Rectus femoris 2. Number of origin ex. Biceps – muscle of the arm with 2 heads Triceps – muscle with 3 heads 3. Action ex. Extensor cruris Flexor tarsi anterior 4. Shape of the muscle ex. Deltoid 5. Attachment ex. Scapulohumeralis (origin – scapula, insertion – deltoid ridge of
humerus 6. Size of the muscle ex. Gracilis major Gracilis minor
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Dorsal Muscles of the Head and TrunkTemporalis - Muscle posterior to the eye
and about the level of tympanic membrane
Action – raise the lower jaw and closes the mouth
Depressor mandibulae - Flattened muscle posterior
to the temporalis muscle Action – depress the jaw Dorsalis scapula(e) - large, broad muscle
underneath the depressor mandibulae
Action – abduct the arm
Temporalis
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Latissimus dorsi - large, flat, triangular
muscles posterior to the depressor mandibulae
Action – draws the forelimbs upward and backward
Longissimus dorsi - Muscle posterior to the L.
dorsi tapering posteriorly Action – extends the back
and elevates the head
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Iiolumbaris - muscle lateral to the Longissimus dorsi Action – bends the back Coccygeosacralis - paired - small V shaped muscle immediately posterior to
Longissimus dorsi Action – draws the back and the urostyle nearer to each other Coccygeoiliacus - pair of V shaped muscle posterior to the coccygeo-
sacralis Action - fixes the urostyle and helps extend the back
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Ventral Muscle of the Head, Trunk and AbdomenMylohyoid - thin, broad, transverse
muscle divided into halves my median longitudinal c. tissue (median raphe) on the ventral side of the floor of the mouth
Action – raises the floor of the mouth during swallowing and breathing
Geniohyoid - flat muscle underneath the
mylohyoid Action – draws the hyoid
forward and upward
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Sternoradialis - median pair of muscles partly covered by the
mylohyoid Action – flexor of the forearm Deltoid (Scapulohumeralis) - thick muscle that passes obliquely to the
sternoradialis Action – prime mover for arm adduction Triceps brachii (upper arm) - large muscle on the posterior side of the
upper arm Action – prime mover for extension of the
forearm Biceps brachii (upper arm) Action – flex the forearm Pectoralis muscle - (anterior, middle and posterior) Action – adductor and rotator of the arm
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Rectus abdominis - large muscle that forms the ventral
abdominal wall linea alba- median ventral connective tissue dividing the muscle into longitudinal halves inscriptiones tendinae - divides the muscle into segments Action - compress and support the abdomen External oblique - outer muscle that forms the lateral wall of
the abdomen - fibers obliquely directed Action – constrict the abdomen Transversus abdominis - innermost muscle of the abdomen - thin muscle underneath the external oblique Action – constrict the abdomen
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Dorsal Muscles of the ThighTriceps femoris - largest and most anterior 3
headed muscle of the thigh Action – draws the hind limb
forward and extends the leg Gluteus - small but thick muscle found
anterior to the Vastus externus and medial to the Rectus femoris anticus
Action – rotates the femur forward
Biceps femoris (Iliofibularis ) - slender muscle posterior to the
triceps Action – flex the leg
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Semimembranosus - large muscle with oblique
markings posterior to Biceps femoris
Action – adducts the thigh, flex and extend the shank
Pyriformis - slender, short muscle found
between the V. externus and proximal end of Semimembranosus
Action – pulls the urostyle to one side
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Dorsal Muscles of the Shank
Gastrocnemius - largest and most posterior muscle of the shank Action – flexor of the leg and
extensor of the foot Peroneus - anterior to the Gastrocnemius - antagonist of Gastrocnemius Action - ? Tibialis anticus - most anterior muscle of the shank and splits into two slips Action – extensor of the leg ,
flexor of the foot
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Ventral Muscles of the Thigh
Sartorius - flat muscle that runs obliquely
downwards Action – flexor of the thigh Adductor longus - flat muscle underneath the Sartorius Action – pulls thigh ventrally and forward Adductor magnus - thick, triangular muscle posterior
to the adductor longus Action – pulls the thigh forward,
adductor or abductor of the thigh