Anatomy of thorax /certified fixed orthodontic courses by Indian dental academy

ANATOMY OF
THORAX
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


BONES- RIB CAGE


THE RIBCAGE
• There are 12 ribs on each side, the no may be
increased by a cervical or a lumbar rib or it
may be reduced to 11 by the absence of 12 th
rib.
• The gaps between the ribs are called as
intercostal spaces. These spaces are deeper in
front than behind, and deeper between the
upper than between the lower ribs.
• The ribs are placed obliquely, the upper being
less oblique than the lower.
• The length of the ribs increases from the first
to the 7 th ribs,and then gradually decreases
th
th
from 7 to 12 ribs.

• The breadth of the ribs decreases from above
downwards. In the upper ten ribs the anterior
ends are broader than post ends.
• The first seven ribs which are connected
through there cartilages to the sternum are
called true ribs, or vertebrosternal ribs.
• The remaining are false ribs , out of these the
cartilages of 8 th ,9 th and 10 th are joined to the
next higher cartilage
( vertebrochondral
ribs), while the anterior ends of the 11 th and 12 th
ribs are free and are called floating ribs
( vertebral ribs).
• The costal cartilages represent the unossified
ant parts of the ribs. They are made up of
hyaline cartilage. They contribute materially to
the elasticity of the thoracic wall.

POSTERIOR VIEW


THE STERNUM
•

The sternum is a flat bone, forming the anterior median
part of the thoracic skeleton. In shape it resembles a
short sword.

•

Three parts:- 1) upper part- manubrium
2) middle part- body
3) lower part- xiphoid procs
MANUBRIUM: the anterior border is thick, rounded and
concave. It is marked by a suprasternal notch in the
median part, and by the clavicular notch on each side.

•

The clavicular notch articulates with the medial end of
the clavicle to form the sternoclavicular joint.

XIPHOID PROCESS:- smallest part of the sternum, it is at
first cartilagenous but in adult it becomes ossified near
its upper end.
• It varies greatly in shape and may be bifid or perforated.

THE MUSCLES
• There are two sets:
1) EXTRINSIC MUSCLES
2) INTERCOSTAL MUSCLES
• Extrinsic muscles:-pectoralis major
-trazepius
-serratus anterior
-latissimus dorsi
-levator scapulae
-rhomboideus major
- Rhomboideus minor
-serratus post sup
-Serratus post inf

INTERCOSTAL MUSCLES:- external intercostal muscle
- internal intercostal muscle
- transversus thoracis muscle( 3 parts)
1)subcostalis
2)intercostalis intimi
3)sternocostalis
NERVE SUPPLY:• The intercostal nerves are the ant primary rami of spinal
nerves t1 to t11. the primary ramus of the 12 th thorasic
nerve forms the subcostal nerve.
•

In addition to supplying the intercostal spaces yhe upper
three intercostal nerves also supply the upper limb, and
the lower five intercostal nerves(t7 to t11) also supply
the abdominal wall.

•

The remaining nerves(t4,5,6) supply only the thoracic
wall and so are called typical intercostal nerves.

MUSCLES


INTERNAL VIEW


THE MEDIASTENUM

•

The mediastenum is the median septum of the thorax between
the two lungs.

•

BOUNDRIES:ant- sternum
post- vertebral colum
sup- thoracic inlet
inf- diaphragm
on each side- mediastinal pluera

•

DIVISIONS:- superior mediastenum
- inferior mediastenum(ant, middle and post mediastenum)

•

The inf mediastenum is subdivided into 3 parts.the area infront
of the pericardium is ant mediastenum, the area behind the
pericardium is post mediastenum and the pericardiuum and its
contents form the middle mediastenum.

•

SUPERIOR MEDIASTENUM:BOUNDRIES: ant- manibrium sterni
post- upper 4 thoracic
vertebrae
sup- plane of the thoracic
duct
inf- an imaginary plane passing through the sternal
angle in front, and the lower border of the 4 th throcic vertebrae
behind.
CONTENTS:muscles-sternohyoid, sternothyroid
arteries- arch of aorta, bracheocephalic artery, left common
carotid artery,and left subclavian artery
veins- r & L bracheocephalic veins, l sup intercostal vein
nerves- vagus, pherinic, cardiac nerves and l recurrent
laryngeal nerve
thymus
thoracic duct

Note: there is very little loose connective tissue between the mobile organs therefore
, the space can be readily www.indiandentalacademy.com fluids and neoplasms.
dilated by the inflamatory

• ANTERIOR MEDIASTENUM :lymphnodes, lowest part of thymus
• Middle mediastenum- heart,
ascending aorta, pulmonary trunk,
2 pulmonary veins, and bifurcation
of trachea
• Posterior mediastenum:oesophagus, vagi and splanchnic
nerves.

CAROTID BODY AND SINUS


• The carotid body (glomus) contains
chemoreceptors that are activated primarily by
low oxygen levels
arterial blood and, to a lesser extent, by low
blood pH or high levels of carbon dioxide in the
blood.
• consists of a mass of spongy tissue located at
the bifurcation of the common carotid artery
into its internal and external carotid branches.
It has its own independent arterial and venous
connections.
• Innervation of the carotid body occurs via the
carotid sinus nerve, which contains afferent
fibers that join the glossopharyngeal nerve (IX)
and autonomic efferent fibers derived from the
vagus nerve (X). The afferent fibers from the
carotid body play an important role in
increasing respiration in response to a drop in
blood oxygen levels.

• The carotid sinus is a thin-walled, elastic
section of the internal carotid artery, the wall of
which contains stretch receptors. These
receptors are mechanoreceptive endings of
afferent nerve fibers that reach the sinus via
the glossopharyngeal nerve (IX) and carotid
sinus nerves.
• The carotid sinus receptors function as
baroreceptors, informing the central nervous
system about blood pressure within the artery.
Strong stimulation (pressure) on these
receptors results in reflex bradycardia and a
marked fall in blood pressure, and may lead to
loss of consciousness as well (carotid sinus
syncope).
• Since the more sensitive baroreceptive endings
are active even at normal blood pressure
levels, this reflex is constantly acting to restrict
the heart rate and blood pressure.

RESPIRATION


MUSCLES OF RESPIRATION


PNEUMOTHORAX(OPEN/SUCKING)


• Open pneumothorax (air in the pleural cavity)
usually results from a penetrating wound of the
chest wall, including the parietal pleura, and is
always a serious condition.
• In an open or "sucking" wound of the
chest wall (so-called because a sucking sound
is often audible as air is sucked into the pleural
cavitythrough the wound), the lung on the
affected side is exposed to atmospheric
pressure, which results in the lung's collapse
and a shift of the mediastinum to the
uninvolved side. Air passes into the chest more
easilyon inspiration than it can leave during
expiration, and this permits a progressive
collapse of the lung.
• As the lung on the affected side is collapsed,
the increased pleural pressure there pushes
the mediastinum to the uninvolved side,
thereby diminishing the contralateral lung

TREATMENT


HAEMOTHORAX
•

Hemothorax (accumulation of blood within the pleural
cavity) is common in both penetrating and
nonpenetrating injuries to the chest.

•

If the hemorrhage is large, it may cause not only
hypovolemic shock but also dangerously reduced vital
capacity by compressing the lung on the involved side.

•

Persistant hemorrhage usually arises from an intercostal
or internal thoracic artery, and less frequently from the
major hilar vessels.

•

Blood in the pleural cavity normally does not clot
because of the smooth surfaces, the defibrinating action
that occurs with the motions of respiration, and the
presence of an anticoagulant enzyme.

TREATMENT
•

A minimal amount of blood (less than 350 ml) can resorb
spontaneously, and conservative management without
thoracentesis is sufficient.

•

If the hemothorax is greater than minimal, or if
hemopneumothorax is found, intercostal tube
thoracostomy should be performed.

•

A large tube is passed through the chest wall at either
the 4th intercostal space laterally or the 2nd intercostal
space anteriorly.

•

Under local anesthesia, a skin incision is made and blunt
dissection is carried out with a gloved finger to prevent
inadvertent lung puncture by the tube should
unsuspected pleural adhesion be present. tube is then
connected to underwater-seal drainage.

•

If the hemothorax is massive, two tubes are placed in the
chest to evacuate www.indiandentalacademy.com
the blood rapidly and permit the lung
to expand.

HEIMLICH MANEUVER
• The Heimlich maneuver to expel an
obstructing mass in the airway is an
effective and safe rescue procedure.
• The maneuver is a technique whereby
subdiaphragmatic compression, or
abdominal "thrust,"creates an expulsive
force from the lungs to or through the
upper airways.
• The consequent velocity ofairflow is
often sufficient to forcefully eject an
obstructing object from the airway.

POSITION OF THE RESCUER’S HANDS


ADULT VICTIM


INFANT VICTIM


SELF SAVE PROCEDURE


AUSCULTATION


• (1) Patient sitting up, leaning forward, and,
preferably, in expiration. This position
increases the contact of the apex of the heart
with the anterior chest wall, and is preferred for
auscultation of mitral and left ventricular
sounds and relatively high-pitched murmurs
using the stethoscope diaphragm. The sitting
up, leaning forward position is preferred
particularly for aortic diastolic murmurs.
• (2) Patient supine. This position is best for
pulmonic and tricuspid murmurs.
• (3) Patient in left lateral recumbent (left
decubitus) position. The low-pitched filling
sounds during diastole are heard best in this
position using the stethoscope bell. This
position causes tachycardia and accentuates
the rumbling murmur of mitral stenosis.

DELTO PERCTORAL FLAP
• Indications:
- The flap may serve at almost any head
and neck level below the Ipsilateral
eyebrow or below the mid level of the
Contralateral face.
- The delto pectoral flap can be used for
either external cover or intra oral lining or
both simultaneously.
- It can also be combined with pectoralis
major musculo cutaneous flap.

• ANATOMY
- Two contiguous but separate axially
vascularised zones are present.
- Intercostal perforating branches from
internal mammary artery.
- Cutaneous vessel from
thoracoacromial artery.
- When the flap is elevated its survival
depends entirely on the flow of blood in
the branches form the internal mammary
to the pectoral zone.

• OPERATIVE TECHNIQUES:
1) ROTATION TRANSFER: This open flap can
resurface the entire adjacent side or front of
the neck.
This greatly simplifies the decision in RND to
sacrifice cervical skin infiltrated with advanced
cancer or severely damaged by prior radiation.
2) SUBCUTANEOUS TRANSFER: This transfer
through the dissected neck with the flap pedicle
deepithelialized, simulating an island flap, may
be used for covering a high cervical and carotid
area defect.
This tech eliminates the need for division of the
pedicle in a second stage and may bring
welcome protection to the dissected neck as
well as contour augmentation.

• 3) BRIDGING OVER THE NECK:
This tech is employable for intra oral defects.
With the pedicle tube and with an intervening
span of intact cervical skin form the donor area,
is a more commonly employed method for
transfer to locations on the head.
Additionally, splitting the flap end, folding it to
provide two layers, and deepithelialize the
folded edge ,if necessary are auxillary
maneuvers that may be used on a special
circumstances.

DELTO SCAPULAR SKIN FLAP
Indications:
•

- The location of its base inferior to posterior
neck skin, which commonly receives radiation
in cases of head and neck cancer and which
constitutes the base of the classic shoulder
flap.
• -Its arc of rotation,which extends to difficult to
reach occipital and post neck wounds.
• - Its use as an additional source of tissue
when other methods are failed or not feasible.
ANATOMY:
•

- The blood supply is from the perforating
branches of the post inter costal arteries.

OPERATING TECHNIQUES:
•

The inferior incision is always started as far
medial as the forth and fifth thorasic vertebral
spine and may even be back cut if necessary to
improve the mobility.
• The flap is gradually tappered while distally
incorporating the thinner, more pliable skin of
the deltoid region and upper extremities.
DELAYED MULTIPLE STAGE TECH:
•

This is by limiting medial undermining to a
vertical line at the lateral border of the neck.
• IN initial stage sup and inf incisions are
made,which are followed in 10- 14 days by
undermining.
• 10-14 days later,the distal end is incised.The
flap may be transferred in 2-3 days,when
vialibility is assertained

LATTISMUS DORSI MUSCULO
CUTANEOUS FLAP
• Indication:
• - It has proved esp useful in resurfacing
defects of the cheek and lateral scalp.
• - It is used in areas when a great deal of
bulk or skin or both are needed.
• - It used for reestablishing oropharyngeal continuity, the musculo
cutaneous flap had been used with the
skin portion placed inward and with skin
graft placed in the exposed muscle
surface.
• - Free lattismus dorsi has been used as
a muscle alone with skin graft cover.

• ANATOMY:
• - The primary blood supply to the muscle
comes primarily from the thoracodorsal
artery,secondary contributions from
perforating branches of the lower post
intercostal arteries.
• - The secondary blood supply,originating
in the intercostal vessels that also
nourish the ribs,is important in head and
neck reconstructions and forms the basis
of osteomusculo cutaneous flap that
carried viable rib with muscle based only
on the thoraco dorsal vessels

•

OPERATING TECHNIQUES:

•

1) Muscle and mucocutaneous flap: An incision is made
just beyond the free edge of the muscle to expose the
vascular pedicle.
The incision is carried post to koin the incised skin
island, which is sutured to the muscle fascia early in the
prodcedure to avoid shearing any musculocutaneous
perforators.
The muscle is dissected superficial to the serratus
anterior and the scapula.
If a transfer of vascularised rib is planned,the perforators
to the rib are preserved,otherwise all the post vessels
are divided.

•

•
•

•

2) Free flap tech:

•

It is similar to that of the muscle flap, except the
insertion of the muscle is divided s well


CERVICO HUMERAL FLAP
• Indications:
• - It is used to cover the anterior cervical
defects or to situations where other
alternatives are not available.
• Anatomy:
• - The dominant vascular pedicle to the
trapezius is the transverse cervical
artery.
• The skin over the deltoid on the lateral
proximal arm is supplied by the post
circum flex humeral artery

• OPERATING TECHNIQUE:
• - The standard procedure is to perform a
preliminary delay 10days prior to definitive
rotation of the cervico humeral flap.
• - The initial delay consists of parallel incisions
of the distal 10-12 cms of the flap with the
subfacial underminig of the included skin.
• This delay ligates the post circum flex humeral
artery.
• Definitive rotation of the flap requires
mobilization proximally to the acromioclavicular
joint, including detachment of the trapezius
muscle from the spine of the scapula.
• The arm donor site has been skin grafted in
every case.

PECTORALIS MAJOR
• Indications: Oro-Pharynx: resection of
the lateral floor of the mouth, alveolar
ridge, Post half of the tounge,and
piriform sinus requires sufficient skin
and bilk for reconstruction’s.
• Orbital Exenteration: This flap is
particularly useful for reconstruction in
this area because it provides bulk and
well vascularized tissue to fill the cavity,
to seal CSF leaks, and to provide
greater protection against bacterial
invasion.
• Temporal bone resection
• Mandibular reconstruction

•

Anatomy: The dominant blood supply is the Thoraco
acromial artery( a branch of sub clavian artery).

•

Operative technique:
-Donor site: Skin paddle- Incise along the infero
lateral portion of the skin paddle first.
A dermis of the skin paddle is sutured to the muscle
fascia with several interrupted sutures along the entire
skin paddle as a dissection proceeds around the paddle.
Once the skin is incised along the Infero lateral border of
the outline, the muscle fibers are split to enter the sub
pectoral space.

Once the muscle is dissected from the sub pectoral
fascia the vascular pedicle in this fascia is separated
from the muscle.
CLOSURE OF THE DONOR SITE: Although some surgeons
covered chest donor site with skin grafts, literature says
it’s totally unnecessary

• RECEPIENT SITE: Orbital exenteration
A PMMC flap is planned with the width
equivalent to the length sufficient to fill the
orbital cavity with soft tissue.

The skin is removed from the distal 4-6 cms, the
exposed muscle and soft tissues are used to fill
the orbital cavity, and the margins of the skin
of the flap are sutured to the skin edges of the
orbit.
MANDIBULAR RECONSTRUCTION: A PMMC flap
incorporating a segment of underlying rib to
reconstruct a jaw, the body and symphysis of
the Mand were reconstructed with the attached
rib while the floor of the mouth and chin were
reconstructed with the overlying double paddle
musculo cutaneous flap.

SCAPULAR FLAP
• Indications: It is useful for repair of
a combined, composite defect of
the tongue floor of the mouth, mand
and neck skin.
• Anatomy: The sub scapular artery
branches within a few mm of its
origin from the axial artery into the
circumflex scapular artery and
thoraco dorsal artery.

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