Download V. Trunk Muscles

V. Trunk Muscles
*Trunk muscles include…
1. those that move the vertebral column
2. anterior thorax muscles, which move the
ribs, head, and arms
3. muscles of the abdominal wall, which
help to move the vertebral column and
form the muscular girdle of abdominal
body wall
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
V. Trunk Muscles
1. Anterior Muscles
a. Pectoralis major: a large, fan-shaped muscle
covering the upper part of the chest
function = to adduct & flex the arm
b. Intercostal Muscles (refer to Fig. 6.21 on p. 210 of
text book): deep muscles found between the ribs
that play a role in breathing
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
V. Trunk Muscles
c. Abdominal Muscles: they contain & protect
the abdominal organs/contents & are very
strong
i. Rectus abdominis: the most superficial
muscles of the abdomen that run from the pubis
to the rib cage & commonly are called “the abs”
-main function is to flex the vertebral column,
compress the ab contents during defecation &
childbirth and also are involved in forced
breathing
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
V. Trunk Muscles
ii. External oblique: paired superficial muscles that make
up the lateral walls of the abdomen
-functions are to flex the vertebral column and rotate the
trunk & bend it laterally
iii. Internal oblique: paired muscles deep to the external
obliques
-their fibers run at right angles to those of external
obliques
-same function as external obliques
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
V. Trunk Muscles
iv. Transverse abdominis: the deepest muscle of the
abdominal wall whose fibers run horizontally across the
abdomen
-function is to compress the abdominal contents
v. Diaphragm: the muscle that separates the thoracic cavity
from abdominal cavity
-dome shaped muscle that is the main muscle in
respiration
-when diaphragm contracts, thoracic cavity expands,
allowing lungs to expand and us to breathe in air
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
V. Trunk Muscles
2. Posterior muscles
a. Trapezius: most superficial muscles of the
posterior neck & upper trunk that forms a
diamond- or kite-shaped muscle mass
- function: to extend the head & elevate, depress,
adduct, and stabilize the scapula
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
2. Posterior Trunk Muscles
b. Deltoid: fleshy, triangle-shaped muscles that
form the rounded shape of your shoulders
-these bulky muscles are also a good injection site
when small amounts of medication must be given
into muscle
- function: prime movers of arm abduction
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
VI. Muscles of the Upper Limb
1. Biceps brachii: the most familiar muscle of the forearm
because it bulges when the elbow is flexed
-function= the powerful prime mover for flexion of the
forearm
2. Triceps brachii: the only muscle filling out the posterior
humerus
-function = the powerful prime mover of elbow
extension; it’s the antagonist of the biceps brachii muscle
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings