Skeletal Muscles Thorax & Back Practical

Question 1

External intercostals

Answer 1

pulls ribs toward one another to elevate rib cage
aid in inspiration
synergists of diaphragm

Question 2

internal intercostals

Answer 2

muscles of posterior abdominal wall and oblique muscles of the abdominal wall
they draw the ribs together and depress the rib cage
aid forced expiration
antagonistic to external intercostals

Question 3

diaphragm

Answer 3

prime mover of inspiration
flattens on contraction
when strongly contracted, dramatically increases intra-abdominal pressure

Question 4

rectus abdominis

Answer 4

flex and rotate lumbar region of vertebral column
fix and depress ribs
stabilize pelvis during walking
increase intra-abdominal pressure
used in sit-ups, curls

Question 5

external oblique

Answer 5

flex vertebral column and compress abdominal wall
increase intra-abdominal pressure
acting individually, aid muscles of back in rotating trunk and flexing laterally
used in oblique curls

Question 6

internal oblique

Answer 6

flex vertebral column and compress abdominal wall
increase intra-abdominal pressure
acting individually, aid muscles of back in rotating trunk and flexing laterally
used in oblique curls

Question 7

transversus abdominis

Answer 7

compresses abdominal contents

Question 8

pectoralis minor

Answer 8

with ribs fixed, draws scapula forward and downward

with scapula fixed, draws rib cage superiorly

Question 9

pectoralis major

Answer 9

adducts and medially rotates arm against resistance; clavicular part assists in flexion when arm is extended and sternal part assists in extension when the arm is flexed
with scapula (and arm) fixed pulls rib cage upward
helps in climbing, throwing, pushing and forced inspiration

Question 10

latissimus dorsi

Answer 10

prime mover of arm extension
powerful arm adductor
medially rotates arm at shoulder
depresses scapula
plays important role in lowering arm in a power stroke, as in striking a blow, hammering, swimming and rowing
with arms fixed overhead it pulls the rest of the body upward and forward, as in chin-ups