14 - intercostal space
TRANSCRIPT
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Thorax Region of the body between
the neck and abdomen Flattened in front and
behind, but rounded on thesides
The bony framework of thewalls is called the thoraciccage, which is formed of:
Vertebral columnposteriorly
Ribs & intercostal spaceson the sides
Sternum and costalcartilages anteriorly
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Superiorly: It communicates withthe neck through an openingbounded:
Posteriorly by 1st thoracicvertebra
Laterally by medial border ofthe 1st ribs and their costal
cartilages Anteriorly by superior border of
manubrium sterni
This opening is occupied:
In the midline, by the structuresthat pass between the neck andthe thorax
On either sides, it is closed by adense suprapleural membrane
1
1st rib
Suprapleural
membrane
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Suprapleural Membrane Tent shaped dense fascial sheet that
covers the apex of each lung.
An extension of the endothoracicfascia
Extends approximately an inchsuperior to the superior thoracic
aperture It is attached:
Laterally to the internal border ofthe first rib & costal cartilage
At its apex to the transverseprocess of C7 vertebra.
Medially to the fascia covering thestructures passing through thesuperior thoracic aperture
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Inferiorly: Itcommunictes with the
abdomen through alarge opening bounded:
Posteriorly by the 12ththoracic vertebra
Laterally by curvingcostal margin
Anteriorly by xiphisternal
joint This opening is closed
by the diaphragm
Costal margin
2th rib
12
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The thoracic cage:
Protects the lungs, heart
and large vessels Provides attachment to
the muscles of thorax,
upper limb, abdomen &
back
The cavity of thorax is
divided into:
A median partition, themediastinum
Laterally placed pleurae &
lungs
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Cutaneous Nerves Anterior wall:
Above the level of sternalangle: Supraclavicular nerves
Below the level of sternal
angle: Segmental innervation
by anterior and lateral
cutaneous branches of the
intercostal nerves
Posterior wall:
Segmental innervation byposterior rami of the thoracic
spinal nerves nerves
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Thoracic Dermatomes
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The Intercostal Space
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Intercostal Space
It is the space between two ribs
Since there are 12 ribs on each side,
there are 11 intercostal spaces. Each space contains:
Intercostal muscles
Intercostal neurovascular bundle
Lymphatics
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Internal Intercostal Muscle
Intermediate layer
Fibers directed downward &backward
Origin: from subcostal grooveof the rib above
Insertion: upper border of ribbelow
Extends from the sternum infront to the angle of the ribbehind
Deficient posteriorly &replaced by internal (posterior)intercostal membrane
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Innermost Intercostal Muscle
Deepest layer
Incomplete layer,divided into three
portions
Fibers cross more than
one intercostal space
Related externally to
intercostal nerve and
vessels, and internallyto endothoracic fascia
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Endothoracic Fascia
It is the extrapleural fasciathat lines the wall of thechest
It is located between themuscles and bones of thethoracic wall and the parietalpleura, extends over the apex(cupola) of the pleura as thesuprapleural membrane, andforms a thin layer betweenthe diaphragm and thepleura.
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Intercostal Nerves
Twelve pairs
Are the anterior primary
rami ofthe thoracic spinal
nerves.
1-6 distributed in theintercostal spaces, 7-11th
supply the anterior
abdominal wall
Anterior ramus of12th nerveruns forward in the
abdomen as the subcostal
nerve
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Intercostal Nerves contd
These are mixed nerves & supply the:
The skin Muscles of the intercostal space & abdomen
The parietal pleura & parietal peritoneum
Branches:
Rami communicantes
Collateral branches
Lateral cutaneous
Anterior cutaneous Muscular branches
Pleural
Peritoneal (7th-11th)
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Intercostal Arteries
Each intercostal space contains:
Asingle posterior &
Two anterior intercostal arteries
Each artery gives off branches to the muscles,
skin, parietal pleura (& breast)
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Posterior Intercostal Arteries
In the upper two spaces,arise from the superiorintercostal artery (abranch of costocervicaltrunk of the subclavianartery)
In the lower nine spaces,arise from the branchesofthoracic aorta
The course andbranching of the
intercostal arteriesfollow the intercostalnerves
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Applied Anatomy
Sternum:
used for marrow biopsy
May be split to make surgical access to heart, greatvessels and thymus
Sternal angle as an important landmark for countingribs, costal cartilages and intercostal spaces
Thoracic outlet syndrome: Compression of nerves/vessels at the superior aperture of thorax
Cervical rib
Referred pain: Disease in the thorax may reveal pain inthe anterior abdominal wall Why?
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