Naming Skeletal Muscles
Named according to a number of criteria:
• Direction of muscle fibers relative to longitudinal axis of the muscle
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Rectus: Fibers oriented straight with respect to longitudinal axis
Oblique: Fibers run at an angle to the longitudinal axis
Orbicularis: Fibers run in a circular path
Relative size
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Major for bigger and minor for smaller;
Maximus for biggest, intermedius for middle and minimus for smallest
Longus for longest and brevis for shortest.
• Location
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Location of the origin and insertion
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Biceps means two heads
Triceps means three heads
Shape
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Brachioradialis attaches to the humerus (origin) and the radius (insertion)
Number of origins
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Pectoralis major is found in the chest region
Rectus femoris is found near the femur
Deltoid means triangular in shape.
Trapezius is shaped like a trapezium or kite
Action
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Flexor and extensor
Adductor and abductor
Skeletal Muscles Of Facial Expression
Skeletal Muscles Of Facial Expression
• Frontalis: Lies over forehead; wrinkles forehead
and raises eyebrows
• Orbicularis oculi: Encircle eye; close eyes, squint,
blink and wink
• Zygomaticus: From cheek to corner of mouth;
raises corners of mouth for smiling
• Orbicularis oris: Present in lips; closes mouth and
protrudes lips
• Mentalis: In mental region; wrinkles chin,
protrudes lower lip
• Buccinator: Thin muscles, attach to orbicularis
oris; compress cheek as in whistling and sucking
Skeletal Muscles Of Mastication
• Masseter: Powerful muscle covering lateral
aspect of mandibular ramus; elevates
mandible during chewing
• Temporalis: Covers parts of temporal, frontal
and parietal bones; works with masseter to
elevate mandible during chewing
• Digastric: Two bellies united by an
intermediate tendon, forming V shape under
the chin; open mouth and depress mandible
Muscles That Act The Head And Neck
• Sternocleidomastoid:
Extends from
manubrium of sternum
and clavicle to mastoid
process of temporal;
flexes and rotates the
head laterally
Muscles Of Respiration
External intercostals: Lie between
ribs; fibers run downwards and
anteriorly; pull ribs towards one
another to lift rib cage
Internal intercostals: Lie between
ribs; fibers run deep and at right
angles to external intercostals
(i.e. run downward and
posteriorly); depress rib cage
Diaphragm
Muscles Of Respiration
• Diaphragm: Broad muscle, pierced by aorta, inferior vena cava and
oesophagus; forms floor of thoracic cavity; fibers converge from margins of
thoracic cage towards central tendon; prime muscle for inspiration
Muscles Of Abdominal Wall
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Rectus abdominis: Medial superficial
muscle pair extending from pubis to
rib cage; segmented by 3 tendinous
intersections; used in sit ups and curls
External oblique: Largest and most
superficial of 3 lateral muscles; fibers
run downward and medially; flex
vertebral column and compress
abdominal cavity
Internal oblique: Most fibers run
upward and medially
Transverse abdominis: Deepest layer,
fibers run horizontally; compress
abdominal contents
Linea Alba: Tendinous raphe (seam)
between right and left rectus
abdominus
Muscles Of Anterior Thorax
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Pectoralis major: Large fan-shaped
muscle covering superior part of
chest; major muscle for flexion,
rotation and adduction of arm
Serratus anterior: Fan-shaped
muscle, inferior to pectoral muscles
on lateral rib cage; deep to scapula;
origins have saw-tooth appearance;
rotates scapula to inferior angle
laterally and upwards
Trapezius Of Posterior Thorax
• Kite-shaped flat muscle
• Upper fibers run inferiorly
to scapula
• Middle fibers run
horizontally to scapula
• Lower fibers run superiorly
to scapula
• Major muscle for stabilizing,
raising, retracting and
rotating scapula
Muscles Of Posterior Thorax
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Trapezius: Most superficial muscle of
posterior thorax; stabilizes, raises,
retracts and rotates scapula
Levator scapulae: Located at back
and side of neck, deep to trapezius;
elevates or adducts scapula
Rhomboids: Deep to trapezius,
inferior to levator scapulae; the
minor muscle is more superficial;
stabilize scapula
Muscles Of The Arm
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Pectoralis major: Prime mover of arm
flexion
Latissimus dorsi: Prime mover of arm
extension
Deltoid: Thick, rounded shoulder mass,
common site of intramuscular injection;
prime mover of arm abduction
Biceps brachii: Two-headed fusiform
muscle; stabilizes shoulder joint; flexes
elbow joint and supinates forearm
Brachialis: Strong muscle, immediately
deep to biceps brachii on humerus; major
forearm flexer
Brachioradialis: Superficial muscle of
lateral forearm, extends from distal
humerus to distal forearm; forearm flexer
Triceps brachii: Large fleshy muscle of
posterior compartment of arm, has 3
heads (long and lateral heads lie superficial
to medial head); powerful forearm
extensor
Latissimus dorsi
• Broad, flat triangular muscle
of lower back; covered by
trapezius superiorly
• Powerful mover of arm
extension, adducts arm and
medially rotates arm at
shoulder
Rotator Cuff Muscles
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Group of 4 muscles and their tendons in
the shoulder
Muscles form a cuff around shoulder joint
and attach at upper portion of arm
– Supraspinatus: Deep to trapezius,
superior to scacpular spine; stabilizes
shoulder joint, prevents downward
dislocation of humerus
– Infraspinatus: Partially covered by
deltoid and trapezius, inferior to
scapular spine; rotates humerus
laterally
– Teres minor : small elongated
muscle, inferior to infraspinatus
muscle; rotates humerus laterally
– Subscapularis: Forms part of
posterior wall of axilla, tendon passes
in front of shoulder joint; chief
medial rotator of humerus
Muscles Of The Thigh, Leg, Foot And Ankle
Muscles Of The Thigh, Leg, Foot And Ankle
Muscles Of The Thigh, Leg, Foot And Ankle