Anatomy of Thoracic Wall.pdf

Thoracic Wall
Assistant Professor
Muhammad Arif Afridi | Sonologist
BS (Radiology), MPH, MS Ultrasound
Email: drarifafridi@gmail.com
“ in the name of Allah the most beneficent the most merciful. ”
1
Assistant Professor Muhammad Arif Afridi | Radiology

by the thoracic part of the vertebral
column
by the sternum and costal cartilages
by the ribs and intercostal spaces
by the suprapleural membrane
by the diaphragm, which separates
the thoracic cavity from the abdominal
cavity
Posteriorly
Laterally
Anteriorly
Superiorly
Overview
Thoracic Wall
Assistant Professor Muhammad Arif Afridi | Radiology 2

• Region of the body between the neck and the
abdomen.
• Flattened in front and behind but rounded at the sides.
• Exteriorly > Skin and muscles of the shoulder girdle.
• Inner surface > parietal pleura.
• Skeletal framework of thoracic walls called thoracic
cage.
• Thoracic cage protects the lungs and heart
• Provides attachment for the muscles of the thorax,
upper extremity, abdomen, and back.
Overview
Thoracic Wall

• The lungs are covered by a thin
membrane called the visceral pleura.
which passes from each lung at its
root (i.e., where the main air
passages and blood vessels enter)
• The inner surface of the chest wall,
where it is called the parietal pleura.
• In this manner, two membranous
sacs called the pleural cavities are
formed.
Overview
Thoracic Wall

• The sternum is the elongate, flat bone
that lies in the midline of the anterior
chest wall.
• The adult sternum consists of three
parts:
1. Manubrium
2. Body
3. Xiphoid process
Osteology
Thoracic Wall Sternum

• Superior part of the sternum.
• Articulates with the body of the sternum at the
manubriosternal joint.
• Articulates
1. with clavicles
2. with the first costal cartilage
3. upper part of the second costal cartilage
4. Lies opposite the third and fourth thoracic
vertebrae
Osteology
Manubrium

• The suprasternal (jugular) notch is the easily
palpable, concave notch on the superior border of
the manubrium.
• The clavicular notch is an ovoid articular
surface at each superolateral corner of the
manubrium, on each side of the jugular notch.
• Each holds the sternal end of a clavicle.
Osteology
Manubrium

• The body is the relatively long, middle part of the
sternum.
• It articulates above with the manubrium at the
manubriosternal joint and below with the
xiphoid process at the xiphisternal joint.
• It articulates with the second to the seventh
costal cartilages on each side
Osteology
Body

• The xiphoid process is the small, most inferior
part of the sternum.
• thin plate of cartilage that becomes ossified at its
proximal end during adult life.
• No ribs or costal cartilages attach to it.
• However, seventh costal cartilage may have a
shared attachment with the xiphoid process and
the body
Osteology
Xiphoid Process

• The xiphisternal joint lies opposite the body
of the ninth thoracic vertebra.
• The inferior end of the xiphoid provides
attachment for the line aalba of the
abdominal wall.
Osteology
Xiphoid Process

• The articulation of the manubrium with the body
forms the sternal angle (angle of Louis).
• which can be recognized by the presence of a
transverse ridge on the anterior aspect of the
sternum.
• Important landmark
1. manubriosternal joint (fibrocartilaginous joint).
2. attachment points of the second costal
cartilages (attach to both manubrium and
body).
3. a horizontal line that typically projects
posteriorly onto the T4 intervertebral disc.
4. the plane of separation between the superior
and inferior mediastina.
Osteology
Angle of Louis

There are 12 pairs of ribs, all of which are
attached posteriorly to the thoracic vertebrae.
The ribs are divided into three categories
according to their relation to the sternum:
False ribs: The 8th, 9th, and 10th pairs of
ribs are attached anteriorly to each other and
to the 7th rib by means of their costal
cartilages.
True ribs: The upper seven pairs are attached
anteriorly to the sternum by their costal
cartilages
Floating ribs: The 11th and 12th
pairs have no anterior attachment
Osteology
Thoracic Wall Ribs

Osteology
Thoracic Wall Ribs
Typical Rib
A typical rib is a long, twisted, flat bone
having a rounded, smooth superior
border
and
a sharp, thin inferior border
A rib has a head, neck, tubercle, shaft,
and angle
The inferior border forms
THE COSTAL GROOVE
which accommodates the intercostal
vessels and nerve.
intercostal vein
intercostal artery
intercostal nerve
VAN

7 cervical
is composed of 33 vertebrae
12 thoracic
5 lumbar
5 sacral
(fused to form the sacrum)
4 coccygeal
(the lower 3 are commonly fused)
Osteology
Thoracic Wall Vertebral Column

Osteology
Thoracic Wall Vertebra
The vertebral arch gives rise to seven processes:
a-One spinous
b-Two transverse
c- Four articular
(2 superior 2 inferior)
A typical thoracic vertebra consists
of:
1-a rounded body anteriorly (body
bearing)
2-a vertebral arch posteriorly.
(protect the spinal cord)
They enclose a space called
The vertebral foramen
through which run the spinal cord and
its coverings

The body is heart shaped
The vertebral foramen is
small and circular
The spines are long and
inclined downward
Costal facets are present on
the sides of the bodies for
articulation with the heads of
the ribs
Costal facets are present on
the transverse processes for
articulation with the
tubercles of the ribs
Characteristics of a Typical Thoracic Vertebra

The body and the vertebral arch are connected by means of pedicles

The pedicles
are notched on their
upper and lower borders
Forming
the superior and inferior
vertebral notches.
These foramina, in an
articulated skeleton, serve to
transmit the spinal nerves
and blood vessels.
On each side
the superior notch of one
vertebra and the inferior
notch of an adjacent
vertebra together form an
intervertebral foramen.

Thoracic Apertures
1. The chest cavity communicates with the root of
the neck through a narrow opening called the
superior thoracic aperture, or thoracic outlet.
• This is called an outlet because important vessels
and nerves emerge from the thorax here to enter
the neck and upper limbs.
2. The thoracic cavity communicates with the
abdomen through a large opening called the
inferior thoracic aperture.

Superior
thoracic aperture
Outlet
1. obliquely directed,
2. facing upward and forward,
3. Conveys
i. esophagus,
ii. trachea,
iii. several vessels and nerves.
Because of the angled tilt of the opening,
the apices of the lungs and pleurae
project upward into the neck at C7.
posterior boundary > Body of the first thoracic
vertebra
lateral boundaries > medial edges of the first
ribs and their costal cartilages
anterior border > superior margin of the
manubrium sterni.

Inferior thoracic aperture
• Posterior boundary: body of the 12th thoracic
vertebra.
• Anterior border:
• lateral boundaries of the curving costal margin,
• the xiphisternal joint.
• Inferior aperture: diaphragm
• esophagus, aorta are passing through thoracic
and abdominal cavities

Suprapleural Membrane
• The thoracic outlet transmits structures that pass between the thorax
and the neck and for the most part lie close to the midline.
• A dense fascial layer called the suprapleural membrane closes the
thoracic outlet on either side of these structures.
• Tent-shaped fibrous sheet attaches
• Laterally > medial border of the first rib & costal cartilage;
• medially > fascia investing the structures passing from the thorax into
neck; and, at its apex.
Fascial Functions
Connective tissue layer
1. Separation
2. Connect
3. Stabilized

Endothoracic Fascia
• a thin layer of loose connective tissue
• separates the parietal pleura from the thoracic wall
• Suprapleural membrane is a thickening of Endothoracic fascia.

Intercostal Spaces
• Intercostal spaces are the gaps between adjacent ribs.
• A needle passing through the entire depth of an intercostal space must penetrate seven structural
layers.
• These are most pronounced in the lateral aspect of the thoracic wall.
• In superficial to deep sequence, the layers are the following:
1. Skin
2. Superficial fascia
3. Deep fascia
4. Intercostal muscles
5. Endothoracic fascia
6. Extra pleural fatty layer
7. Parietal pleura

Three intercostal muscles
fill the intercostal spaces:
1. external intercostal
2. internal intercostal
3. innermost intercostal.

Diaphragm
• The diaphragm is a thin muscular
and tendinous septum that
separates the chest cavity above
from the abdominal cavity below.
• Structures that pass between the
thoracic and abdominal cavities
(e.g., esophagus, aorta) must
either pierce the diaphragm or go
around the diaphragm.

The diaphragm is a thin muscular
and tendinous septum that
separates
the chest cavity above
from
the abdominal cavity below
The diaphragm is the most
important muscle of respiration.
It is dome shaped and consists
of a
peripheral muscular part
and a centrally placed tendon
The diaphragm

The inferior vena cava
passes through the central tendon
at approximately vertebral
level T8
The esophagus
passes through the muscular part
of the diaphragm, approximately
at vertebral
level T10
The aorta passes behind the
posterior attachment of the
diaphragm at vertebral
level T12
Main Openings in the diaphragm

Components
• It is dome shaped
• Consists of a peripheral
muscular part, which
arises from the margins
of the thorax, and a
centrally placed
tendon.
Domes or Cupola of diaphragm Tendinous part (central tendon)x
Muscular part
Base of the diaphragm

Diaphragm origin
The origin of the diaphragm can
be divided into 3 parts:
1. sternal part arising from the
posterior surface of the
xiphoid process.
2. costal part arising from the
deep surfaces of the lower six
ribs and their costal cartilages.
3. vertebral part arising by
vertical columns (crura) and
from the arcuate ligaments.

1. Sternal part 2. Costal part 3. Vertebral part

Attachments
• Xiphoid process anteriorly (T8-T9)
• Costal margin of the thoracic wall
• Ends of ribs XI and XII;
• Ligaments & crura that span across
structures of the posterior
abdominal wall
• Vertebrae of the lumbar region.
Median arcuate ligament
Medial arcuate ligaments
Lateral arcuate ligaments

Crura
• Right crus arises from first three
lumbar vertebrae and intervertebral
discs.
• Left crus arises from bodies of the
first two lumbar vertebrae and
intervertebral disc.
• Lateral to the crura, the diaphragm
arises from the medial and lateral
arcuate ligaments.

1. Medial arcuate ligament extends
from the side of the body of the
second lumbar vertebra to the tip of
the transverse process of the first
lumbar vertebra.
2. Lateral arcuate ligament extends
from the tip of the transverse process
of the first lumbar vertebra to the
lower border of the 12th rib.
3. Median arcuate ligament which
crosses over the anterior surface of
the aorta, connects the medial borders
of the two crura.

Central tendon
• The diaphragm inserts into a central
tendon, which is shaped like three leaves.
• The superior surface of the tendon is
partially fused with the inferior surface of
the fibrous pericardium.
• Some of the muscle fibers of the right crus
pass up to the left and surround the
esophageal orifice in a sling like loop.
• These fibers appear to act as a sphincter
and possibly assist in the prevention of
regurgitation of the stomach contents into
the thoracic part of the esophagus.

Structures pass through
T10
T8
T12

Nerve supply
•Motor:
• Phrenic nerve (C3,4,5)
•Sensory (proprioceptive)
• Costal margin by intercostal nerves
• Central area by phrenic nerves

Blood supply
• Costal margin (Lateral): lower five intercostal and
subcostal arteries
• Muscle fibers arising from crura (posterior): Left & right
inferior phrenic arteries from abdominal aorta.
• Other contributions (Interior and Superior):
pericardiacophrenic & musculophrenic from internal thoracic
artery superior phrenic from thoracic aorta.

Actions
Inspiration / Breath in
Abdominal straining

Terminology
• Artery term use Supply
• Vein and Lymphatic system term use Drainage
• Nerve term use Innervation
• Arterial System
1. Main arteries and their origination
2. Continuation of main arteries
3. Branches of main arteries & region that they supply
• Venous system
• Blood circulate in the order from the Branched vein to large vein.

thoracic aorta,
subclavian artery and
axillary artery supply
the thoracic walls.
Vasculature

The subclavian artery
provides blood through
its superior intercostal
and internal thoracic
branches.
Vasculature

The axillary artery
supplies via its superior
thoracic and lateral
thoracic branches.
Vasculature

The thoracic aorta gives
off posterior intercostal
and subcostal
branches.
Vasculature

Internal Thoracic Artery
The internal thoracic artery
supplies the anterior wall of the
body from the clavicle to the
umbilicus.
It is a branch of the first part of the
subclavian artery in the neck.
It descends vertically on the pleura
behind the costal cartilages

fingerbreadth lateral to the
sternum, and ends in the
sixth intercostal space,
dividing into the superior
epigastric and
musculophrenic arteries

Two anterior intercostal
arteries supply the upper
six intercostal spaces.
Perforating arteries
accompany the
terminal branches of
the corresponding
intercostal nerves. Pericardiacophreni artery
accompanies the phrenic
nerve and supplies the
pericardium.
The superior epigastric
artery enters the rectus
sheath of the anterior
abdominal wall and
supplies the rectus muscle
as far as the umbilicus.
musculophrenic artery
runs around the costal
margin of the diaphragm
and supplies the lower
intercostal spaces and
the diaphragm.

Homework
• Learn all muscles name, origin, insertion, nerves name and action
• Vasculature

Intercostal Arteries & Veins
• Each intercostal space contains:
1. A large single posterior
intercostal artery
2. Two small anterior intercostal
arteries

Posterior intercostal arteries
• The posterior intercostal arteries of the first two spaces are branches
from the superior intercostal artery.
• Which is a branch of the costocervical trunk of the subclavian artery.
• The posterior intercostal arteries of the lower nine spaces are branches
of the descending thoracic aorta.

Anterior intercostal arteries
• The anterior intercostal arteries of the first six spaces are branches of
the internal thoracic artery.
• which arises from the first part of the subclavian artery.
• The anterior intercostal arteries of the lower spaces are branches of
the musculophrenic artery.
• Which is the terminal branches of the internal thoracic artery.

Thank You!
60
Assistant Professor Muhammad Arif Afridi | Radiology

Anatomy of Thoracic Wall.pdf

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