CHAPTER 2 : THORAX PART 1 : THORACIC WALL Flashcards
Contained within the protective thoracic cage are the important
life-sustaining organs—lungs, heart, and major blood vessels.
In
addition, the lower part of the cage overlaps the upper abdominal
organs, such as the liver, stomach, and spleen, and offers them considerable protection.
Although the chest wall is strong,
- *blunt or penetrating wounds** c**an injure the soft organs beneath
it. **
T or F
True
This is especially so in an era in which automobile accidents,
stab wounds, and gunshot wounds are commonplace.
■■ Because of the clinical importance of the chest wall, examiners
tend to focus on this area.
Questions concerning the ribs and
their movements; the diaphragm, its attachments, and its function;
and the contents of an intercostal space have been asked
many times.
What is thorax?
The thorax (or chest) is the **region of the body between the neck**and the**abdomen**
Describe the outside appearance of thorax.
It is flattened in front and behind
but rounded at the sides.
Define and describe the thoracic cage.
The framework of the walls of the
thorax, which is referred to as the thoracic cage.
Thoracic cage is formed
by the :
- BEHIND :vertebral column
- EITHER SIDE: the ribs and intercostal spaces on
- FRONT: sternum and costal cartilages in
Superiorly, the thorax communicates with the
________
neck
inferiorly thorax is separated from the abdomen by
the______
diaphragm
The thoracic cage protects the lungs and
heart and affords attachment for the muscles of the thorax,
upper extremity, abdomen, and back.
What is the mediastinum?
The cavity of the thorax can be divided into a median
- *partition, called the mediastinum**, and the laterally placed
- *pleurae and lungs**.
What is a visceral pleura?
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) to the inner surface of the chest wall, where it is called the parietal pleura.
How are the pleural cavities formed?
The cavity of the thorax can be divided into a median
partition, called the mediastinum, and the laterally placed pleurae and lungs.
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) to 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, one on
each side of the thorax, between the lungs and the thoracic
walls.
Structure of the Thoracic Wall
- Sternum
- Ribs
- Costal Cartilages
- Intercostal Spaces
- Intercostal Muscles
- Intercostal Arteries and Veins
- Intercostal Nerves
- Suprapleural Membrane
- Endothoracic Fascia
- Diaphragm
- Internal Thoracic Artery
- Internal Thoracic Vein
- Levatores Costarum
- Serratus Posterior Superior Muscle
- Serratus Posterior Inferior Muscle
Sternum
- body of the sternum
- xiphoid process
- sternal angle (angle of Louis),
- xiphisternal joint
The sternum lies in the ___________
midline of the anterior chest wall.
What type of bone is the sternum?
It is a flat bone.
Sternum can be divided into three parts:
- manubrium sterni,
- body of the sternum,
- and xiphoid process.
Describe manubirum.
The manubrium is the upper part of the sternum.
Manubrium articulates
with the body of the sternum at the ____________
manubriosternal
joint,
Manubrium
also articulates with the :
- clavicles and
- the 1st costal cartilage
- and the upper part of the 2nd costal cartilages
- on each side (see Fig. 2.1).
Sternum lies opposite the __________ vertebrae.
3rd
and 4th thoracic
The body of the sternum articulates above with the
manubrium at the manubriosternal joint and below with
the xiphoid process at the_______
xiphisternal joint.
The body of the manubrium articulates on each side,
with the ___________
2nd to the 7th costal cartilages
Discuss the xiphoid process.
The xiphoid process (see Fig. 2.1) is a thin plate of cartilage that becomes ossified at its proximal end during adult
life.
No ribs or costal cartilages are attached to the xiphoid process.
T or F
TRUE
The sternal angle (angle of Louis), formed by the articulation
articulation of the manubrium with the body of the sternum,
The sternal angle can be recognized by the presence of ____________(Fig. 2.2).
a transverse ridge onthe anterior aspect of the sternum
The transverse
ridge lies at the level of the ___________
2nd costal cartilage, the point
from which all costal cartilages and ribs are counted.
The sternal angle lies opposite the intervertebral disc between
the ___________vertebrae.
4th and 5th thoracic
The xiphisternal joint lies opposite the body of the
__________ vertebra
ninth thoracic
Sternum and Marrow Biopsy
Why is the Sternum a common site for 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 thebone.
The sternum may also be split at operation to allow
the surgeon to gain easy access to the heart, great vessels,
and thymus.
T or F
True
Describe the Ribs.
There are 12 pairs of ribs, all of which are attached posteriorly
to the thoracic vertebrae
L is the 12th letter of the alphabet
Love is for heart
L is for lungs
Alll of which is contained in side the thoracic cavity
The ribs are divided into three categories:
- True ribs:
- False ribs:
- Floating ribs
Describe the True ribs
The upper seven pairs are attached anteriorly to
the sternum by their costal cartilages.
Upper Seven Heaven
Describe the false ribs.
False ribs:
The 8th, 9th, and 10th pairs of ribs are attached
anteriorlyto each other and to the7th rib by means of
their costal cartilages and small synovial joints.
Describe the floating ribs.
Floating ribs: The 11th and 12th pairs have no anterior
attachment
Desribe the TYPICAL RIB.
A typical rib is a long, twisted, flat bone having a rounded,
smooth superior borderand asharp, thin inferior border
(see Figs. 2.4 and 2.5).
Describe the inferior border of the ribs.
The inferior border overhangs and
forms the costal groove, which accommodates the intercostal
vessels and nerve.
The anterior end of each rib is
attached to the corresponding costal cartilage
What are the parts of the ribs?
A rib has a head, neck, tubercle, shaft, and angle
Describe the head of the rib.
The head has two facets for articulation
with the numerically corresponding vertebral body
and that of the vertebra immediately above
Discuss the neck part of the ribs.
The neck is a constricted portion situated between the
head and the tubercle
Discuss the tubercle of the rib.
The tubercle is a prominence on
- *the outer surface** of the rib at the junction of the neck
- *with the shaft.**
What is the function of the tubercle?
It has a facet for articulation with the
transverse process of the numerically corresponding vertebra
Describe the shaft of the rib.
The shaft is thin and flattened and
twisted on its long axis.
Its inferior border has the costal
groove.
” nasa baba ng rib ang intercostal vessel so always remember to puncture or insert needle superiorly”
Descirbe the angle of the ribs.
The angle is where the shaft of the rib bends
sharply forward.
What is the ATYPICAL RIB?
First RIB.
Why is the first rib clinically important?
The 1st rib is important clinically because of its close relationship to the lower nerves of the brachial plexus and the main vessels to the arm, namely, the subclavian artery and vein (Fig. 2.6).
Describe the
Describe the first rib.
This rib is small and flattened from above
downward.
What is attached to the upper surface and inner border of the first rib?
The scalenus anterior muscle is attached to its
upper surface and inner border.
Anterior to the scalenus
anterior,what vesses crosses the rib?
the subclavian vein crosses the rib
posterior to the scalenus
anterior attachment, what crosses the ribs?
the subclavian artery and the lower trunk of the brachial plexus cross the rib and lie in contact with the bone.
Describe the Costal Cartilages
Costal cartilages are bars of cartilage connecting the upper seven ribs to the lateral edge of the sternum and the 8th, 9th, and 10th ribs to the cartilage immediately above.
The cartilages of the 11th and 12th ribs end in the _________(see Fig. 2.1).
abdominal
musculature
What is the function of the costal cartilages?
The costal cartilages contribute significantly to the elasticity
and mobility of the thoracic walls.
In old age, the
costal cartilages tend to lose some of their flexibility as the
result of superficial calcification.
T or F
T
Joints of the Chest Wall
Joints of the Sternum
- manubriosternal joint
- xiphisternal joint
manubriosternal joint
The manubriosternal joint is a cartilaginous joint
between the manubrium and the body of the sternum.
A small amount of angular movement is possible during
respiration
describe xiphisternal joint
The xiphisternal joint is a cartilaginous joint
between the xiphoid process (cartilage) and the body of the
sternum.
T
The xiphoid process usually fuses with the body
of the sternum during middle age.
T or F?
T
Joints of the Ribs
- Joints of the Heads of the Ribs
- Joints of the Tubercles of the Ribs
- Joints of the Ribs and Costal Cartilages
- Joints of the Costal Cartilages with the Sternum
Joints of the Heads of the Ribs
The 1st rib and the three lowest ribs have a s
single synovial joint with their corresponding vertebral body. ‘
For the
2nd to 9th ribs, the head articulates by means of a :
synovial
joint with the corresponding vertebral body and that of
the vertebra above it (see Fig. 2.4). There is a strong intraarticular
ligament that connects the head to the intervertebral
disc
Joints of the Tubercles of the Ribs
The tubercle of a rib articulates by means of a synovial
joint with the transverse process of the corresponding vertebra
(see Fig. 2.4). (This joint is absent on the 11th and
12th ribs.)
Joints of the Ribs and Costal Cartilages
These joints are cartilaginous joints. No movement is
possible.
Joints of the Costal Cartilages with the Sternum
The 1st costal cartilages articulate with the (see Fig. 2.1).
manubrium, by cartilaginous joints that permit no movement
The 2nd to 7th costal cartilages articulate with ________________.
the lateral
border of the sternum by synovial joints
In addition, the
6th, 7th, 8th, 9th, and 10th costal cartilages articulate with
one another along their borders by small synovial joints.
The cartilages of the 11th and 12th ribs are embedded in
the _________
abdominal musculature.
Movements of the Ribs and Costal Cartilages
The 1st ribs and their costal cartilages are fixed to the manubrium
and are immobile.
The raising and lowering of the
ribs during respiration are accompanied by movements in
__________________
both the joints of the head and the tubercle, permitting the neck of each rib to rotate around its own axis.
Openings of the Thorax
What is the thoracic outlet?
The chest cavity communicates with the root of the neck through an opening called the thoracic outlet.
Why is it called thoracic outlet?
It is called an outlet because important vessels and nerves emerge from the thorax here to enter the neck and upper limbs.
What are the bounderies of the thoracic outlet?
- The opening is bounded posteriorly by the 1st thoracic vertebra,
- laterally by the medial borders of the 1st ribs and their costal cartilages, and
- anteriorly by the superiorborder of the manubrium sterni.
Describe the opening of the thoracic outlet.
The opening is obliquely
placed facing upward and forward.
Through this small
opening pass the esophagus and trachea and many
vessels and nerves.
Because of the obliquity of the opening,
the apices of the lung and pleurae project upward
into the neck
The thoracic cavity communicates with the abdomen
through a large opening.
What are the bounderieS?
The opening is bounded:
- posteriorly by the 12th thoracic vertebra,
- laterally by the curving costal margin, and
- anteriorly by the xiphisternal joint.
Through this large opening, which is closed by the diaphragm, pass the esophagus and many large vessels andnerves, all of which pierce the diaphragm.
What is the Thoracic Outlet Syndrome?
The brachial plexus of nerves (C5, 6, 7, and 8 and T1) and the subclavian artery and vein are closely related to the upper surface of the 1st rib and the clavicle as they enter the upper limb
(see Fig. 2.6).
It is here that the nerves or blood vessels may
be compressed between the bones.
Most of the symptoms are
caused by pressure on the lower trunk of the plexus producing pain down the medial side of the forearm and hand and wasting of the small muscles of the hand.
- *Pressure on the blood**
- *vessels may compromise the circulation of the upper limb.**
Intercostal Spaces
The spaces between the ribs contain three muscles of respiration.
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 _____________ (Fig. 2.8).
intermediate and
deepest layers of muscles
What is the arrangement of the intercostal vessels?
They are arranged in
the following order from above downward:
- intercostal vein,
- intercostal artery,
- and intercostal nerve (i.e., VAN).
Intercostal Muscles
- external intercostal muscle
- anterior (external) intercostal membrane
- internal intercostal muscle
- innermost intercostal muscle
Describe the external intercostal muscle.
The external intercostal muscle forms the most superficial
layer.
Its fibers are directed downward and forward
- *from the inferior border of the rib above to the superior**
- *border of the rib below** (see Fig. 2.8).
The external intercostal muscle extends
forward to the costal cartilage where it is replaced by an
aponeurosis, the _______
anterior (external) intercostal membrane
Describe the internal intercostal muscle.
The internal intercostal muscle forms the intermediate
layer.
Its fibers are directed downward and backward
from the subcostal groove of the rib above to the upper border of the rib below (see Fig. 2.8).
The internal intercostal muscle. extends
backwardfrom the sternum in front to the angles of the
ribs behind, where the muscle is replaced by an aponeurosis,
the ___________(see
Fig. 2.9).
posterior (internal) intercostal membrane
Describe the innermost intercostal muscle.
The innermost intercostal muscle forms the deepest
layer and corresponds to the transversus abdominis muscle in the anterior abdominal wall.
It is an incomplete muscle
layer and crosses more than one intercostal space within the ribs.
It is related internally to fascia (endothoracic fascia)
and parietal pleura and externally to the intercostal
nerves and vessels.
The innermost intercostal muscle can be divided into three portions (see Fig. 2.9), which are more or
less separate from one another.
What happens when the intercostal muscles contract?
When the intercostal muscles contract, they all tend to
pull the ribs nearer to one another.
What happens during insipiration with the intercostal muscles?
If the 1st rib is fixed
by the contraction of the musclesin the root of the neck,
namely, the scaleni muscles, the intercostal muscles raise
the 2nd to the 12th ribstoward the 1st rib, as in inspiration.
What happens duing expiration with the intercostal muscles?
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.**
How does the intercostal muscles help in the intrathoracic pressure?
In
addition, the tone of the intercostal muscles during the
different phases of respirationserves tostrengthen the tissues
of the intercostal spaces,thuspreventing the sucking
in or the blowing out of the tissues with changes in
intrathoracic pressure.For further details concerning the
action of these muscles, see Mechanics of Respiration on
Intercostal Arteries and Veins
Each intercostal space contains a
- large single posterior intercostal artery
- and two small anterior intercostal arteries.
posterior intercostal arteries of the first two spaces
are branches from?
The posterior intercostal arteries of the first two spaces
are branches from the superior intercostal artery, a
branch of the costocervical trunk of the subclavian
artery.
The posterior intercostal arteries of the lower
nine spacesare branches of the :
descending thoracic
aorta
The anterior intercostal arteries of
the lower spacesarebranches of the____________
musculophrenic artery, one of the terminal branches of the internal
thoracic artery.
Each intercostal artery gives off branches to the muscles,
skin, and parietal pleura. In the region of the breast in the
female, the branches to the superficial structures are particularly
large.
The corresponding posterior intercostal veins drain
backward into the __________ (Figs. 2.10
and 2.11),
azygos or hemiazygos veins
anterior intercostal veins drain forward
into the_____________
internal thoracic and the musculophrenic veins.
What are the intercostal nerves?
The intercostal nerves are the anterior rami of the first
11 thoracic spinal nerves (Fig. 2.12).
What is the 12th intercostal nerve?
The anterior ramus of
the 12th thoracic nervelies in theabdomen and runs forward in the abdominal wall as thesubcostal nerve.
Describe how the intercostal nerve enters the intercostal space.
Each intercostal nerve enters an intercostal space
between the parietal pleuraand theposterior intercostal
membrane(see Figs. 2.8 and 2.9).
It then runs forward
inferiorly to the intercostal vessels in the subcostal groove
of the corresponding rib,between the innermost intercostal
and internal intercostal muscle.
The first six nerves are
distributed within their _____
intercostal spaces.
The 7th to 9th
intercostal nerves leave the anterior ends of their intercostal
spaces by passing deep to the costal cartilages, to enter the
___________
anterior abdominal wall.
The 10th and 11th nerves, since
the corresponding ribs are floating, pass directly into the
abdominal wall.
Intercostal nerve branches
- Rami communicantes connect the intercostal nerve to a ganglion of the sympathetic trunk (see Fig. 1.26). The gray ramus joins the nerve medial at the point at which the white ramus leaves it
-
collateral branch runs forward inferiorly to the
main nerve on the upper border of the rib below. - lateral cutaneous branch runs forward inferiorly to the main nerve on the upper border of the rib below.
- anterior cutaneous branch
- Muscular branches run to the intercostal muscles.
- Pleural sensory branches go to the parietal pleura.
-
Peritoneal sensory branches (7th to 11th intercostal
nerves only) run to the parietal peritoneum
The first intercostal nerve is joined to the ______________.
brachial plexus
by a large branch that is equivalent to the lateral cutaneous branch of typical intercostal nerves
The remainder of the
first intercostal nerve is small, and there is no anterior cutaneous
branch.
The second intercostal nerve is joined to the medial
cutaneous nerveof the arm by a branch called the ___________ which isequivalent to the lateral cutaneous
branch of other nerves.
intercostobrachial
nerve,
The 2nd intercostal nerve
therefore supplies the skin of the armpit and the upper
medial side of the arm.
With the exceptions noted, the 1st six intercostal nerves
therefore supply the skin and the parietal pleura covering the outer and inner surfaces of each intercostal space, respectively, and the intercostal muscles of each intercostal space
and the levatores costarum and serratus posterior muscles.
In addition, the 7th to 11th intercostal nerves supply the
skin and the parietal peritoneum covering the outer and inner surfaces of the abdominal wall, respectively, and the anterior abdominal muscles, which include the external oblique, internal oblique, transversus abdominis, and rectus
abdominis muscles.
In coronary artery disease, pain
is referred along this nerve to the medial side of the arm.
Second intercostal nerve
What is a Cervical Rib?
A cervical rib (i.e., a rib arising from the anterior tubercle of the transverse process of the 7th cervical vertebra) occurs in about 0.5% of humans (Fig. 2.7). It may have a free anterior end, may be connected tbo the 1st rib by a fibrous band, or may articulate
with the 1st rib.
The importance of a cervical rib is that it
can cause pressure on the lower trunk of the brachial plexus in some patients, producing pain down the medial side of the forearm and hand and wasting of the small muscles of the hand.
It can also exert pressure on the overlying subclavian artery and interfere with the circulation of the upper limb.
What is Rib Excision?
Rib excision is commonly performed by thoracic surgeons wishing to gain entrance to the thoracic cavity.
A longitudinal incision
is made through the periosteum on the outer surface of the rib, and a segment of the rib is removed.
A second longitudinal
incision is then made through the bed of the rib, which is the
inner covering of periosteum. After the operation, the rib regenerates
from the osteogenetic layer of the periosteum
Skin Innervation of the Chest Wall and
Referred Pain
Above the level of the sternal angle, the cutaneous innervation
of the anterior chest wall is derived from the supraclavicular
nerves (C3 and 4). Below this level, the anterior and
lateral cutaneous branches of the intercostal nerves supply
oblique bands of skin in regular sequence. The skin on the
posterior surface of the chest wall is supplied by the posterior
rami of the spinal nerves. The arrangement of the dermatomes
is shown in Figures 1.23 and 1.24.
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.
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.
Herpes zoster, or shingles, is a relatively common condition caused by the reactivation of the latent varicella-zoster virus in a patient who has previously had chickenpox.
The lesion is
seen as an inflammation and degeneration of the sensory neuron in a cranial or spinal nerve with the formation of vesicles with inflammation of the skin. In the thorax, the first symptom is a band of dermatomal pain in the distribution of the sensory
neuron in a thoracic spinal nerve, followed in a few days by a skin eruption.
The condition occurs most frequently in patients
older than 50 years.
Describe the suprapleural membrane.
Superiorly, the thorax opens into the root of the neck by a narrow aperture, the thoracic outlet (see page 39).
The outlet transmits structures that pass between the thorax and the neck (esophagus, trachea, blood vessels, etc.) and for the most part lie close to the midline.
On either side
of these structures, the outlet is closed by a dense fascial layer called the suprapleural membrane (Fig. 2.13). This tent-shaped fibrous sheet is attached laterally to the medial border of the 1st rib and costal cartilage.
It is attached at
its apex to the tip of the transverse process of the seventh cervical vertebra and medially to the fascia investing the
structures passing from the thorax into the neck.
It protects the underlying cervical pleura and resists the changes
in intrathoracic pressure occurring during respiratory
movements.
Thoracic Cage Distortion
The shape of the thorax can be distorted by :
congenital anomalies
of the vertebral column or by the ribs.
Destructive disease
of the vertebral column that produces lateral flexion or
scoliosis results in marked distortion of the thoracic cage.
What is the endothoracic fascia?
The endothoracic fascia is a thin layer of loose connective tissue
that separates the parietal pleura from the thoracic wall.
The suprapleural membrane is a thickening of this fascia.
Describe the diagphragm.
The diaphragm is a thin muscular and tendinous septum
that separates the chest cavity above from the abdominal
cavity below (Fig. 2.16).
It is pierced by the structures that
pass between the chest and the abdomen.
It is dome shaped and consists of a peripheral muscular part, which arises from the margins of the thoracic opening, and a centrally placed tendon (
The
origin of the diaphragm can be divided into three parts:
- sternal part
- costal part
- vertebral part
Where does the sternal part of the diagphram arises?
A sternal part arising from the posterior surface of the
xiphoid process
Where does the costal part of the diaphram arises?
A costal part arising from the deep surfaces of the lower six
ribs and their costal cartilages
Where does the vertebral part of the diagphram arises?
A vertebral part arising by vertical columns or crura and
from the arcuate ligaments
Where does the right crus of the diaphragm arises?
The right crus arises from the sides of the bodies of the first three lumbar vertebrae and the intervertebral discs.
Where does the left crus arises?
the left crus arises from the sides of the bodies of the first two lumbar
vertebrae and the intervertebral disc
Lateral to
the crura the diaphragm arises from the :
medial and lateral arcuate ligaments
The 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.
The lateral arcuate ligament extends from the tip
of the transverse process of the first lumbar vertebra to the lower border of the 12th rib.
The lateral arcuate ligament extends from the tip
of the transverse process of the first lumbar vertebrato thelower border of the 12th rib.
The medial borders of the two
crura are connected by a ________, which
crosses over the anterior surface of the aorta
median arcuate ligament
The diaphragm is inserted into a ______- which
is shaped like three leaves.
central tendon
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 slinglike loop.
These fibers appear to act as a sphincter
and possibly assist in the prevention of regurgitationof the stomach contents into the thoracic part of the esophagus
Traumatic Injury to the Thorax
Traumatic injury to the thorax is common, especially as a result
of automobile accidents.
- Fractured Sternum
- Rib Contusion
- Rib Fractures
- Flail Chest
Traumatic Injury to the Thorax
What is the reason that fracture to the sternum is not common?
The sternum is a resilient structure that is held in position by relatively pliable costal cartilages and bendable ribs.
however, it does
occur in high-speed motor vehicle accidents.
Remember that the
heart lies posterior to the sternum and may be severely contused
by the sternum on impact.
Traumatic Injury to the Thorax
What is the most common rib injury?
Rib Contusion
Bruising of a rib, secondary to trauma, is the most common rib injury.
In this painful condition, a small hemorrhage occurs
beneath the periosteum.
Traumatic Injury to the Thorax
What is the common chest injuries?
Fractures of the ribs are common chest injuries.
Why is rib fracture in children rare?
In children,
the ribs are highly elastic, and fractures in this age group are therefore rare.
Unfortunately, the pliable chest wall in the young
can be easily compressed so that the underlying lungs and heart may be injured.
With increasing age, the rib cage becomes more
rigid, owing to the deposit of calcium in the costal cartilages, and the ribs become brittle.
The ribs then tend to break at their weakest
part, their _________.
angles
What ribs are prone to fracture?
The ribs prone to fracture are those that are exposed or relatively fixed.
Ribs 5 through 10 are the most commonly fractured
ribs.
The first four ribs are protected by the clavicle and pectoral muscles anteriorly and by the scapula and its associated muscles posteriorly.
The 11th and 12th ribs float and move with the force of
impact.
Because the rib is sandwiched between the skin externally and the delicate pleura internally, it is not surprising that the jagged ends of a fractured rib may penetrate the lungs and present
as a pneumothorax.
What is the most important symptom of a fractureed rib?
Severe localized pain is usually the most important symptom of a fractured rib.
The periosteum of each rib is innervated by the
intercostal nerves above and below the rib. To encourage the
patient to breathe adequately, it may be necessary to relieve the
pain by performing an intercostal nerve block.
What is a flail chest?
In severe crush injuries, a number of ribs may break.
If limited
to one side, the fractures may occur near the rib angles and anteriorly near the costochondral junctions.
This causes flail chest, in which a section of the chest wall is disconnected to the rest of the thoracic wall.
If the fractures occur on
either side of the sternum, the sternum may be flail. In either case, the stability of the chest wall is lost, and the flail segment
is sucked in during inspiration and driven out during expiration, producing paradoxical and ineffective respiratory movements
Traumatic Injury to the Back of the Chest
The posterior wall of the chest in the midline is formed by the vertebral column.
In severe posterior chest injuries, the possibility
of a vertebral fracture with associated injury to the spinal cord should be considered.
Remember also the presence of the scapula,
which overlies the upper seven ribs. This bone is covered
with muscles and is fractured only in cases of severe trauma.
Traumatic Injury to the Abdominal Viscera and the Chest
When the anatomy of the thorax is reviewed, it is important to remember that the upper abdominal organs—namely, the liver, stomach, and spleen—may be injured by trauma to the rib cage.
In fact, any injury to the chest below the level of the nipple line
may involve abdominal organs as well as chest organs
Describe the shape of the Diaphragm.
Shape of the Diaphragm
As seen from in front, the diaphragm curves up into right and left domes, or cupulae.
The right dome of the diaphragm reaches as high
as the upper border of what rib?
5th rib,
and the left dome of the diaphragm may reach the lower border of the_______ rib.
5th
What is the reason behind why the right dome of the diaphragm lies higher than the left?
(The right dome lies at a higher level, because of the large size of the right lobe of the liver.)
Where does the central tendon of the diaphragm lies?
The central tendon lies at the level of the xiphisternal
joint.
The domes support the right and left lungs,
whereas the central tendon supports the heart.
The levels of
the diaphragm vary with the :
- phase of respiration,
- the posture,
- and the degree of distention of the abdominal viscera.
How is the diaphragm when a person is sitting or standing?
The diaphragm is lower when a person is sitting or standing
What position is the diaphragm higher?
; it is higher in the supine position and after a large meal.
What is the appearance of the diaphragm when its from the side?
When seen from the side, the diaphragm has the appearance
of an inverted J, the long limb extending up from the
vertebral column and the short limb extending forward to the xiphoid process (see Fig. 2.2).
Nerve Supply of the Diaphragm
Motor nerve supply
The right and left phrenic nerves
(C3, 4, 5)
Nerve Supply of the Diaphragm
Sensory nerve supply
The parietal pleura and peritoneum
covering the central surfaces of the diaphragm are from
the phrenic nerve and the periphery of the diaphragm is
from the lower six intercostal nerves
What is the action of the Diaphragm?
On contraction, the diaphragm pulls down its central tendon and increases the vertical diameter of the thorax.
Functions of the Diaphragm
- Muscle of inspiration
- Muscle of abdominal straining
- Weight-lifting muscle
- Thoracoabdominal pump:
Discuss diaphragm as a muscle of inspiration.
Muscle of inspiration:
On contraction, the diaphragm
pulls its central tendon downandincreases the vertical
diameter of the thorax.
The diaphragm is the most
important muscle used in inspiration.
Describe the diaphragm as a muscle of abdomina straining.
Muscle of abdominal straining:
The contraction of the
diaphragm assists the contraction of the muscles of the anterior abdominal wall in raising the intra-abdominal pressure for micturition, defecation, and parturition.
This mechanism is further aided by the person taking
a deep breath and closing the glottis of the larynx.
The
diaphragm is unable to rise because of the air trapped
in the respiratory tract.
Now and again, air is allowed to
escape, producing a grunting sound.
Discuss Diaphragm as a Weight- ligting muscle.
Weight-lifting muscle:
In a person taking a deep
breath and holding it (fixing the diaphragm), the diaphragm
assists the muscles of the anterior abdominal
wall in raising the intra-abdominal pressure to such an
extent that it helps support the vertebral column and
prevent flexion.
This greatly assists the postvertebral
muscles in the lifting of heavy weights.
Needless to say,
it is important to have adequate sphincteric control of
the bladder and anal canal under these circumstances
Discuss the Diaphragm as a Thoracoabdomina pump.
Thoracoabdominal pump:
The descent of the diaphragm
- *decreases the intrathoracic pressure** and at the
- *same time increases the intra-abdominal pressure.**
This
pressure change compresses the blood in the inferior
vena cava and forces it upward into the right atrium of the heart.
Lymph within the abdominal lymph vessels is also compressed, and its passage upward within the thoracic
ductisaided by the negative intrathoracic pressure.
The presence of valves within the thoracic duct prevents backflow.
Explain how is Thoracotomy done?
Thoracotomy
In patients with penetrating chest wounds with uncontrolled intrathoracic hemorrhage, thoracotomy may be a life-saving procedure.
After preparing the skin in the usual way, the
physician makes an incision over the fourth or fifth intercostal space, extending from the lateral margin of the sternum to the anterior axillary line (Fig. 2.15).
Whether to make a right or
left incision depends on the site of the injury.
For access to the
heart and the aorta, the chest should be entered from the left side.
The following tissues will be incised in thoracotomy (see Fig. 2.14):
(a) skin,
(b) subcutaneous tissue,
(c) serratus anterior and pectoral
muscles,
(d) external intercostal muscle and anterior intercostal
membrane,
(e) internal intercostal muscle, (f) innermost
intercostal muscle,
(g) endothoracic fascia, and
(h) parietal pleura.
What is to be avoided in internal thoracic artery?
Avoid the internal thoracic artery, which runs vertically
downward behind the costal cartilagesabout afingerbreadth lateral to the margin of the sternum, and the intercostal vessels and nerve,whichextend forward in the subcostal groove in the
upper part of the intercostal space (see Fig. 2.14).
What is a hiccup?
Hiccup is the involuntary spasmodic contraction of the diaphragm
accompanied by the approximation of the vocal folds
and closure of the glottis of the larynx
. It is a common condition in normal individuals and occurs after eating or drinking as a
result of gastric irritation of the vagus nerve endings.
It may,
however, be a symptom of disease such as pleurisy, peritonitis, pericarditis, or uremia.
How can the Paralysis of the Diaphragm occur?
A single dome of the diaphragm may be paralyzed by crushing or sectioning of the phrenic nerve in the neck.
This may be necessary
in the treatment of certain forms of lung tuberculosis,
when the physician wishes to rest the lower lobe of the lung on one side.
Occasionally, the contribution from the fifth cervical
spinal nerve joins the phrenic nerve late as a branch from the nerve to the subclavius muscle.
This is known as the accessory
phrenic nerve. To obtain complete paralysis under these circumstances, the nerve to the subclavius muscle must also
be sectioned.
Openings in the Diaphragm
The diaphragm has three main openings:
- aortic opening
- esophageal opening
- caval opening
ACE
Where does the aortic opening lies?
The aortic opening lies anterior to the body of the 12th
thoracic vertebra between the crura (see Fig. 2.16).
Aortic opening transmits what?
It transmits the:
- aorta,
- the thoracic duct,
- and the azygos vein.
Where does the esophageal opening lies?
The esophageal opening lies at the level of the 10th thoracic vertebra in a sling of muscle fibers derived from the right crus (see Fig. 2.16).
What does the esophageal opening transmits?
It transmits the esophagus, the
- *right and left vagus nerves**, the esophageal branches of
- *the left gastric vessels,** and the lymphatics from the lower third of the esophagus.
Where does the caval opening lies?
The caval opening lies at the level of the 8th thoracic
vertebra in the central tendon (see Fig. 2.16).
Ceight!! ( KATE)
What does the caval opening transmits?
It transmits
the inferior vena cava and terminal branches of the
right phrenic nerve.
So the arrangement of the opening on the diaphragm maybe as follows:
CEA
- Caval opening
- Esophageal
- Aorta
In addition to the openings of the diaphragm what else can pierce the diaphragm?
- In addition to these openings, the sympathetic splanchnic nerves pierce the crura; the sympathetic trunks pass posterior to the medial arcuate ligament on each side;
- and the superior epigastric vessels pass between the sternal and costal
origins of the diaphragm on each side (see Fig. 2.16).
What does the Internal Thoracic Artery supplies?
The internal thoracic artery supplies the anterior wall of the body from the clavicle to the umbilicus.
The internal thoracic artery is a branch of the ?
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, a fingerbreadth
lateral to the sternum, and ends in the sixth
intercostal space by dividing into the superior epigastric and musculophrenic arteries (see Figs. 2.9 and 2.1
What are the branches of the Internal Thoracic Artery?
Branches:
■■ Two anterior intercostal arteries for the upper six intercostal spaces
■■ Perforating arteries, which accompany the terminal
branches of the corresponding intercostal nerves
■■ The pericardiacophrenic artery, which accompanies the phrenic nerve and supplies the pericardium
■■ Mediastinal arteries to the contents of the anterior
mediastinum (e.g., the thymus)
■■ The superior epigastric artery, which enters the rectus sheath of the anterior abdominal wall and supplies the rectus muscle as far as the umbilicus
■■ The musculophrenic artery, which runs around the
costal margin of the diaphragm and supplies the lower
intercostal spaces and the diaphragm
Where does the Internal Thoracic Vein drain?
The internal thoracic vein accompanies the internal thoracic artery and drains into the brachiocephalic vein on
each side.
Describe the Levatores Costarum.
Levatores Costarum
There are 12 pairs of muscles
. Each levator costa is triangular
in shape and arises by its apex from the tip of the transverse process and is inserted into the rib below.
What is the action of Levatores Costarum?
■■ Action: Each raises the rib below and is therefore an
inspiratory muscle.
What is the nerve supply of the Levatores Costarum?
■■ Nerve supply: Posterior rami of thoracic spinal nerves.
Describe the Serratus Posterior Superior Muscle
The serratus posterior superior is a thin, flat muscle that
arises from the lower cervical and upper thoracic spines.
Its fibers pass downward and laterally and are inserted into
the upper ribs.
What is the action of Serratus Posterior Superior Muscle?
■■ Action: It elevates the ribs and is therefore an inspiratory muscle.
What is the nerve supply of Serratus Posterior Superior Muscle?
■■ Nerve supply: Intercostal nerves.
What is the Serratus Posterior Inferior MM?
Serratus Posterior Inferior Muscle
The serratus posterior inferior is a thin, flat muscle that
arises from the upper lumbar and lower thoracic spines.
Its fibers pass upward and laterally and are inserted into
the lower ribs
What is the Serratus Posterior Inferior muscle action?
■■ Action: It depresses the ribs and is therefore an expiratory
muscle.
What is the Serratus Posterior Inferior nerve supply?
■■ Nerve supply: Intercostal nerves
FIGURE 2.15 Left thoracotomy
. A. Site of skin incision over fourth or fifth intercostal space
. B. The exposed ribs and associated
muscles. The line of incision through the intercostal space should be placed close to the upper border of the rib to avoid
injuring the intercostal vessels and nerve.
C. The pleural space opened and the left side of the mediastinum exposed. The left
phrenic nerve descends over the pericardium beneath the mediastinal pleura. The collapsed left lung must be pushed out of
the way to visualize the mediastinum
FIGURE 2.16 Diaphragm as seen from below. The anterior portion of the right side has been removed. Note the sternal, costal,
and vertebral origins of the muscle and the important structures that pass through it.
What are your inspiratory muscles?
- Serratus posterior superior
- Levatores costarum (12)
