Download 3_Chest Wall

Chest Wall
Objectives
 Identify the sternum and ribs with their characteristic
features.
 Define intercostal space with its contents.
 Describe intercostal muscles with their nerve supply
and actions.
 Enlist the respiratory muscles with their actions.
 Explain the Bucket handle and pump handle
movements.
Thoracic cage
THORACIC CAGE
Conical in shape
 Formed of:
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Sternum & costal cartilages:
anteriorly
Twelve pairs of ribs: laterally
Twelve thoracic vertebrae:
posteriorly
Has 2 apertures (openings):
1. Superior (thoracic outlet):
narrow, open, continuous
with neck
2. Inferior: wide, closed by
diaphragm
Articulations
Manubriosternal
(fibrocartilagenous J.)
Small angular
Movement possible
Costovertebral
(Synovial joint)
Costochondral
(cartilagenous J.)
no movements
possible
Xiphisternal
(fibrocartilagenous J.)
no significant
movements
Sternocostal
(synovial),
mobile
EXCEPT first,
which is
cartilagenous
& fixed
Thoracic inlet
Boundaries:
a. Anterior: Supra-sternal notch of the manubrium sterni.
b. On each side: First rib.
c. Posterior:
First thoracic vertebra.
Thoracic outlet
Boundaries:
a. Anterior: Xiphoid
process.
b. On each side: Lower six
costal cartilages & Last two
ribs.
c. Posterior: Last thoracic
vertebra.
- It is closed by the
diaphragm which separates
it from the abdominal
cavity.
Ribs
Classification according to their attachments to the sternum:
Total number of Ribs: 12 pairs
A: True ribs: Upper seven ribs (Directly attached to the sternum).
B: False ribs: Lower five ribs (Indirectly attached to the sternum).
The lower two ribs (11th & 12th) are called the Floating ribs because
they are free anteriorly.
Classification of ribs according to their structure:
A: Typical: 3rd - 9th ribs.
B: Atypical:1st, 2nd, 10th, 11th, and 12th ribs. (first two and last 3) ribs.
Typical rib
Atypical ribs
First rib (general features)
Shortest C- Shaped
Ant end: cup shape.
Post end: It has Head,
neck and tubercle.
Head: One facet
Surfaces: Sup. &
Inferior
Borders: Outer (lateral)
& Inner (medial).
Second rib
-Twice the length of 1st
- Head has 2 facets
- Surfaces of shaft are
in between that of 1st
& typical
Tenth rib
a. Single articular facet on
the head.
Eleventh rib
a. Single articular facet
on the head.
b. No tubercle.
Twelveth rib
a. Single articular facet on the head.
b. No tubercle.
c. No neck.
d. No costal groove.
e. Large head.
f. Tapering anterior end.
Sternum
Sternum
 3 PARTS: Manubrium, Body *
Xiphoid process.
 Manubrium: Lies opposite T3,4.
 Body: T5 toT8
 Xiphoid T9
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 Intercostal Spaces
There are 9 anterior and 11
posterior
Each space contains:
1- Intercostal muscles:
(External, Internal and
transversus thoracicus)
2- An Intercostal nerve.
3- Intercostal vessels:
a. Intercostal arteries
(Anterior & Posterior)
b. Intercostal veins
(Anterior & Posterior).
Respiratory Movements
A- Movements of Diaphragm
Inspiration
Contraction (descent)
of diaphragm
Increase of vertical diameter
of thoracic cavity
Expiration
Relaxation (ascent)
of diaphragm)
Respiratory Movements
B- Movements of Ribs
PUMP HANDLE MOVEMENT
Elevation of ribs
Increase in antero-posterior
diameter of thoracic cavity
BUCKET HANDLE MOVEMENT
Elevation of ribs
Increase in lateral diameter of
thoracic cavity
Inspiratory Muscles
Diaphragm (most important muscle)
External intercostal muscles Rib elevators:
Accessory muscles (only used during forced
inspiration):
1. Scalene muscles
2. Pectoralis major
3. Sternomastoid
EXTERNAL INTERCOSTAL
 Attachments: from
lower border of rib
above to upper
border of rib below
 Direction of fibers:
downward &
medially
 Nerve supply:
intercostal nerves
 Action: rib elevators
(inspiratory)
Internal Intercostal
• Is partly traversed by the
nerve & vessels, which
splits each muscle into 2
parts:
• Outer: Internal Intercostal
(proper)
• Inner: Innermost Intercostal
• (In the middle of the space)
• Transversus thoracicus
• The most inner layer of
thoracic wall
• It is formed of 3 muscles
• 1- Innermost Intercostal.
• 2- Sternocostalis.
• 3- Subcostalis
RIB DEPRESSORS
1. Internal intercostal
2. Innermost intercostal
Direction: upward & medially
3. Subcostal
4. Transversus thoracis
Nerve supply: intercostal nerves
(ventral rami of T1-T11)
3
1 2
4
Sternocostalis
• 4 to 5 slips which arise from
inner surface of lower part of
body of sternum and costal
cartilages
• Inserted into inner surface of
costal cartilages from 2 to 6.
Subcostalis
muscle
Thin
bands of muscle
fibers.
Mainly in lower 6 spaces.
Only in post. part of spaces.
Origin: Inner surface & lower
border of rib above.
• Insertion: Upper border of 2nd
or 3rd rib below.
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Expiratory Muscles
Act only during forced expiration
• Rib depressors:
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Internal intercostal
Innermost intercostal
Subcostals
Transversus thoracis
• Anterior abdominal wall muscles:
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External oblique
Internal oblique
Transversus abdominis
Rectus abdominis
It contains:
1- Intercostal muscles.
2- Intercostal nerves.
3- Intercostal arteries.
4- Intercostal veins.
Intercostal muscles
I. Outer layer: External intercostal muscle
II. Intermediate layer: Internal intercostal muscle
III. Inner layer: Transversus thoracis group:
subdivided into:
a. Innermost inter-costalis
b. Sterno-costalis
c. Sub-costalis
Transversus thoracis group
Arrangements and extension of the muscles
Intercostal Arteries
Intercostal Arteries:
1- Anterior Intercostal Arteries.
2- Posterior Intercostal Arteries.
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Anterior Intercostal Arteries
Each anterior intercostal space
contains two anterior
intercostal arteries (except in
the lower two inter-costal
spaces).
a. The upper 6 pairs arise
from the internal thoracic
artery.
b. The 7th, 8th, and 9th pairs
arise from the musculophrenic artery.
Posterior Intercostal Arteries
- Each posterior intercostal space
contains one posterior intercostal
artery which runs in the costal
groove .
*The upper two posterior
intercostal
arteries superior intercostal
artery (from the costo-cervical
trunk)  Subclavian artery.
* From 3 - 11 posterior intercostal
arteries and subcostal artery 
descending thoracic aorta.
Intercostal Nerves
- There are
11 intercostal nerves in the upper 11
intercostal spaces and a subcostal nerve (12th
the last rib (on each side).
) below
- Each intercostal nerve arises from the corresponding
thoracic nerve.
Typical Intercostal Nerves
I. Anterior intercostal veins:
- They correspond to the anterior
intercostal arteries.
- They drain into the venae
comitantes of the
musculophrenic and internal
thoracic
arteries.
II. Posterior Intercostal Veins
Right side:
- 1st +2nd + 3rd post.
intercostal veins unite
to form the right
superior intercostal
vein  azygos vein.
-4th - 11th post. intercostal
veins  azygos vein
-Subcostal vein Azygos
Vein
II. Posterior Intercostal Veins
Left side:
- 1stpost. intercostal vein left
innominate vein.
- 2nd + 3rd post. intercostal veins
unite to form the superior
intercostal vein
- 4th – 8th post. intercostal veins
superior hemiazygos.
- 9th – 11th post. intercostal vein
inferior hemiazygos vein.
- Subcostal vein inferior
hemiazygos vein.
Arrangement of intercostal nerve and
vessels in the costal groove
Branches:
 White & grey rami (1)
communicans with
sympathetic ganglion
 Collateral branch to
Intercostals (2)
 Lateral cutaenous branch to
skin (3)
 Anterior cutaenous (4)
 Muscular branches
 Pleural sensory branches
 peritoneal branches (5)
 Articular branches.
Applied anatomy:
Needles introduced into the intercostal spaces
(to remove collection in the pleura)
Site: They are done in the lateral part of the chest wall.
Cause: To avoid injury of the posterio intercostal nerve
and vessels.
(It is also better to be introduced near the rib below).
Thank you