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SURFACE ANATOMY &
MARKINGS OF THE
THORAX
G.LUFUKUJA
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Bony Landmarks of the thorax
• The thorax (or chest) is the region of the body
between the neck and the abdomen. The jugular notch
is in the same horizontal plane as the lower border of the
body of the second thoracic vertebra (T2)
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Bony Landmarks…
• The sternal angle corresponding to the second costal
cartilage, is at the level opposite the intervertebral disc
between the fourth and fifth thoracic vertebrae is so readily
found that it is used as a starting-point from which to count
the ribs.
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The sternal angle (angle of Louis)
• The angle is formed by the articulation of the manubrium with the
body of the sternum, can be recognized by the presence of a
transverse ridge on the anterior aspect of the sternum. The
transverse ridge lies at the level of the second costal cartilage,
the point from which all costal cartilages and ribs are counted.
The sternal angle lies opposite the intervertebral disc between the
fourth and fifth thoracic vertebrae
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Landmarks…
• Lungs
• The apex of the lung is situated in the neck above the medial
third of the clavicle. The height to which it rises above the
clavicle varies very considerably, but is generally about 2.5 cm.
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Landmarks…
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Landmarks…
• Trachea. This may be marked out on the back by a line from the
spinous process of the sixth cervical to that of the fourth
thoracic vertebra (C6-T4). In front, the point of bifurcation
corresponds to the sternal angle. It’s a point where trachea
bifurcates.
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Landmarks…
• Esophagus.—The extent of the esophagus may be
indicated on the back by a line from the sixth cervical
to the level of the ninth thoracic spinous process (C6T9), 2.5 cm. to the left of the middle line.
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Landmarks…
• Heart:-The apex of the heart is first determined,
either by its pulsation or as a point in the fifth
interspace, 9 cm.
• The position of the various orifices is as follows:
The pulmonary orifice is situated in the upper angle
of the third left sternocostal articulation; the aortic
orifice is a little below and medial to this, close to
the articulation. The left atrioventricular opening is
opposite the fourth costal cartilage, and rather to the
left of the midsternal line; the right atrioventricular
opening is a little lower, opposite the fourth
interspace of the right side.
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Structure of the Thoracic Wall
• The thoracic wall is
covered on the outside by
skin and by muscles
attaching the shoulder
girdle to the trunk. It is
lined with parietal pleura.
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Thoracic vertebra:
 They are 12 in number
Classification:
Typical thoracic vertebra:
Second to Eight
Atypical thoracic vertebra:
First, Nine to Twelve
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Features of typical thoracic vertebra:
Body: It is heart shaped; Presence of two costal demifacets
The transverse process: Tips bear oval costal facets
Spinous process: Long and slopes downward
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Features of typical thoracic vertebra…
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Features of typical thoracic vertebra…
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Atypical thoracic
vertebra:
First, Nine to Twelve
have only a
single pair of
costal facets
Atypical
typical
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Thorax…
• The framework of the walls of the thorax, which is
referred to as the thoracic cage, is formed
posteriory by the vertebral column, the ribs and
intercostal spaces on either side, and the sternum
and costal cartilages in front
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Structure of the Thoracic Wall
• The thoracic wall is formed posteriorly by the thoracic part of
the vertebral column; anteriorly by the sternum and costal
cartilages; laterally by the ribs and intercostal spaces;
superiorly by the suprapleural membrane; and inferiorly by the
diaphragm, which separates the thoracic cavity from the
abdominal cavity
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Skeleton of the Thoracic Wall
• The thoracic skeleton
includes 12 pairs of ribs
and associated costal
cartilages, 12 thoracic
vertebrae
and
the
intervertebral
discs
interposed
between
them, and the sternum.
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Sternum
• The sternum lies in the
midline of the anterior
chest wall. It is a flat
bone that can be divided
into
three
parts:
manubrium sterni, body
of the sternum, and
xiphoid process.
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The manubrium
• The manubrium is the upper part of the sternum. It
articulates with the body of the sternum at the
manubriosternal joint, and it also articulates with the
clavicles and with the first costal cartilage and the upper
part of the second costal cartilages on each side. It lies
opposite the third and fourth thoracic vertebrae
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Applied anatomy
• Sternum and Marrow Biopsy
• Since the sternum possesses red hematopoietic
marrow throughout life, it is a common site for marrow
biopsy. Under a local anesthetic, a wide-bore needle is
introduced into the marrow cavity through the anterior
surface of the bone.
• The sternum may also be split at operation to allow the
surgeon to gain easy access to the heart, great
vessels, and thymus.
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Ribs
• Ribs (L. costae) are the long curved, flat bones that
form most of the thoracic cage
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Ribs…
• There are three types of rib:
• True (vertebrocostal) ribs (1st to 7th ribs): They attach
directly to the sternum through their own costal
cartilages.
• False (vertebrochondral) ribs (8th, 9th, and usually
10th ribs): Their cartilages are connected to the
cartilage of the rib above them; thus their connection
with the sternum is indirect.
• Floating (vertebral, free) ribs (11th, 12th, and
sometimes 10th ribs): The rudimentary cartilages of
these ribs do not connect even indirectly with the
sternum; instead they end in the posterior abdominal
musculature.
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Ribs…
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Ribs…
• Typical ribs (3rd to 9th) have the following components:
• Head: wedge-shaped and has two facets
• Neck: connects the head with the body at the level of the
tubercle
• Tubercle: at the junction of the neck and body and has a
smooth articular part, for articulating with the
corresponding transverse process of the vertebra
• Body (shaft): thin, flat, and curved, most markedly at the
costal angle where the rib turns anterolaterally, the concave
internal surface of the body has a costal groove paralleling
the inferior border of the rib
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Typical ribs (3rd to 9th)
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Intercostal spaces
• Intercostal spaces separate the ribs and their costal
cartilages from one another.
• There are 11 intercostal spaces and 11 intercostal
nerves. Intercostal spaces are occupied by intercostal
muscles and membranes, and two sets (main and
collateral) of intercostal blood vessels and nerves,
identified by the same number assigned to the space.
• The space below the 12th rib does not lie between
ribs and thus is referred to as the subcostal space,
and the anterior ramus of spinal nerve T12 is the
subcostal nerve.
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Intercostal spaces
• The spaces between the ribs contain three muscles of
respiration: the external intercostal, the internal intercostal, and
the innermost intercostal muscle. The innermost intercostal
muscle is lined internally by the endothoracic fascia, which is
lined internally by the parietal pleura. The intercostal nerves and
blood vessels run between the intermediate and deepest layers
of muscles
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Applied anatomy:
Pleural effusion is excess fluid that accumulates
between the two pleural layers, the fluid-filled space
that surrounds the lungs. Excessive amounts of such
fluid can impair breathing by limiting the expansion of
the lungs during ventilation.
Pleural tap
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Applied Anatomy:
Thoracentesis
Sometimes it is necessary to insert a hypodermic needle through
an intercostal space into the pleural cavity (thoracentesis) to
obtain a sample of fluid or to remove blood or pus
Inserting the needle into the 9th intercostal space in the
midaxillary line during expiration will avoid the inferior border of
the lung.
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Intercostal muscles
• Action
• When the intercostal muscles contract, they all tend to pull
the ribs nearer to one another. If the 1st rib is fixed by the
contraction of the muscles in the root of the neck, namely,
the scaleni muscles, the intercostal muscles raise the 2nd
to the 12th ribs toward the first rib, as in inspiration. If,
conversely, the 12th rib is fixed by the quadratus
lumborum muscle and the oblique muscles of the
abdomen, the 1st to the 11th ribs will be lowered by the
contraction of the intercostal muscles, as in expiration.
• Nerve Supply
• The intercostal muscles are supplied by the corresponding
intercostal nerves.
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Vasculature of the Thoracic Wall
• Arteries of the Thoracic Wall
• The arterial supply to the thoracic wall derives from the:
Thoracic aorta, through the posterior intercostal and
subcostal arteries. The internal thoracic arteries. Axillary
artery, through the superior and lateral thoracic arteries
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Applied anatomy:
Referred Pain
• An intercostal nerve not only supplies areas of skin,
but also supplies the ribs, costal cartilages, intercostal
muscles, and parietal pleura lining the intercostal
space. Furthermore, the 7th to 11th intercostal nerves
leave the thoracic wall and enter the anterior
abdominal wall so that they, in addition, supply
dermatomes on the anterior abdominal wall, muscles
of the anterior abdominal wall, and parietal
peritoneum.
• This latter fact is of great clinical importance because
it means that disease in the thoracic wall may be
revealed as pain in a dermatome that extends across
the costal margin into the anterior abdominal wall.
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Applied anatomy:
Referred Pain
For example, a pulmonary thromboembolism or a
pneumonia with pleurisy involving the costal parietal
pleura could give rise to abdominal pain and tenderness
and rigidity of the abdominal musculature. The
abdominal pain in these instances is called referred pain.
Irritation of the mediastinal and central diaphragmatic
areas of the parietal pleura results in pain that is referred
to the root of the neck and over the shoulder
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Lymph Drainage of the Thoracic
Wall
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