Class #9 Chest Muscles and
Bones
Clavicle p.4
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Sternal End
Acromical end
Body
Sternum p.4
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Manubrium: Clavicular notch
Jugular notch
Body: sternal angle- where 2nd rib
attaches to the body, it’s where the
heart is.
Xiphoid Process: be cautious of this
during CPR, landmark for hand
placement
Ribs p.4
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True: make a direct attachment to the
sternum, 1st 7pairs
False: attach anteriorly to each other by
costal cartilages, pairs 8-10
Floating: have no anterior attachments,
ribs 11 & 12
Chest and Abdomen Muscles:
Pectoralis Major:
Sternal and clavicular heads, forms anterior
border of axilla
O: Clavicle, sternum, upper 6ribs
I: Lateral lip of bicipital groove
A: Clavicular head-flexion of humerus at
shoulder joint horizontal adduction.
Sternal head-Flexion of humerous at shoulder
joint
Whole muscle-Adduction at shoulder joint
medial rotation of humerus
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Pectoralis Minor
*brachial plexus (bundle of nerves) runs just
underneath, can get impinged.
O: Ribs 3,4,5
I: coracoid process of scapula
A: -Protraction
-Depression
-Downward rotation-pulls on coracoid in such
a way that glenoid fossa is oriented
downward.
Subclavius
O: 1st rib
I: Clavicle
Holds clavicle in place
Intercostals
3 layers of muscle that lie between your
ribs
External- most superficial
Fiber direction, like putting
hands in pockets
Inhalation/Inspiration
Intercostals cont;
Internal-
Fiber direction, 90 degrees
difference
Exhalation/Expiration
Innermost- Same fiber direction and
same action as internal
Transverse Thoracis- very deep, lies beneath
xiphoid process
Involved with expiration by
depressing the ribs.
Serratus Anterior
O: lateral surface of upper 8 ribs
Looks like serrated edge of knife—runs
close to ribs and between ribs and
scapula before:
I: Anterior vertebral border of scapula
A: Protraction, Holds scapula against ribs.
Serratus Anterior cont:
N: Long thoracic nerve
Serratus Anterior Long Thoracic (jagged
edge of knife, cut steak and then put
SALT on it)
Weak serratus anterior causes winging
out of scapula
Rectus Abdominis
Pubic symphysis/crest > xiphoid process and
costal cartilages of ribs 5,6,7.
2 masses separated by linea alba
Anterior and Posterior rectus sheath cover and
interconnect to form tendinous inscriptions
Actions: Flexion of torso/trunk
helps compress abdominal contents
thereby supporting abdominal
organs and assisting in
forced expiration
Diaphragm
-Looks like a big mushroom
-Primary muscle of respiration
N: Phrenic Nerve
-Flat muscle that divides chest from
abdominal area.
Diaphragm cont:
-Has 3 openings (apertures)
-Vena Caval foramen: allows for
passage of inferior vena cava (brings
back deoxygenated blood to heart)
-Esophageal hiatus: esophagus passes
thru here, about level of T10.
Herniation can occur (hiatal herniastomach pops thru this opening)
Diaphragm cont:
-Aortic hiatus: about level of T12,
descending portion of aorta, carrying
oxygenated blood to body.
Vena Cava = T8
Esophageal = T10
Aortic Hiatus = T12
Set Goals or Achieve Nothing!
Now time for class assignment.
Questions-Chest
1.Which muscle forms the anterior wall of the
axilla?
2. What is the relationship between pectoralis
minor and the brachial plexus?
3. What is the nerve supply to the respiratory
diaphragm?
4. Name the openings of the respiratory
diaphragm and what structures pass through
each openings?
Questions-Chest
5. A weak _____causes winging of the scapula?
6. State the origin, insertion and action for each
muscle in this area:
-Pectoralis Major and Minor
-Subclavius
-Intercostals
-Serratus Anterior
-Rectus Abdominis
-Diaphragm
Questions-Chest
7. List the bony landmarks of the chest:
ribs, sternum, clavicle.
The End!
Quiz next class on the chest and
abdominal muscles.