Title: Skeletal Muscle
1Skeletal Muscle
- Skeletal muscle is attached to bone on each end
by tendons. - Insertion
- More movable attachment.
- Origin
- Are pulled towards it (fixed point).
- Surrounded by connective tissues
2Types of muscles
- Prime mover or agonist (leader)- The muscle that
causes an action - Antagonist (ant against), relaxes while the
prime mover contracts. - Most movements also involve muscles called
synergists, which help the prime mover function
more efficiently by reducing unnecessary
movement. - Fixators stabilizing the origin of the prime
mover so that the prime mover can act more
efficiently.
3Skeletal Muscle
4Naming skeletal muscles
- Most skeletal muscles have names that describe
some feature of the muscle. The following are
some terms relating to muscle features that are
used in naming muscles. - Size vastus (huge) maximus (large) longus
(long) minimus (small) brevis (short). - Shape deltoid (triangular) latissimus (wide)
teres (round) trapezius (like a trapezoid). - Direction of fibers rectus (straight)
transverse (across) oblique (diagonally)
orbicularis (circular).
5Naming skeletal muscles
- Location pectoralis (chest) gluteus (buttock or
rump) brachii (arm) supra- (above) infra-
(below) sub- (under or beneath) lateralis
(lateral). - Number of origins biceps (two heads) triceps
(three heads) quadriceps (four heads). - Origin and insertion sternocleidomastoideus
(origin on the sternum and clavicle, insertion on
the mastoid process) brachioradialis (origin on
the brachium or arm, insertion on the radius). - Action abductor (to abduct a structure)
adductor (to adduct a structure) flexor (to flex
a structure) extensor (to extend a structure)
levator (to lift or elevate a structure)
masseter (a chewer).
6Apneurosis - A sheetlike fibrous membrane,
resembling a flattened tendon, that serves as a
fascia to bind muscles together or as a means of
connecting muscle to bone.
Facial expressions
Mastication
frontalis
neck
7Facial expressions
Mastication
Neck
8Neck superior to hyoid bone
Neck inferior to hyoid bone
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11Thorax and shoulder - superficial
Thorax and shoulder - deep
Abdominal muscles
12External intercostal Origin - lower border of a
rib within an intercostal space Insertion -
upper border of the rib below (muscles of quiet
breathing) Internal intercostal Origin - upper
border of a rib Insertion - lower border of rib
above
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14back and shoulder muscles
Back muscles
Scapula rotators
Rotator cuff
15Abdominal muscles
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17Action on the elbow - flexors
Pronators
Action on the hand - flexors
18Action on the elbow - extensors
Action on the hand - extensors
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