14 - Intercostal Space

7/29/2019 14 - Intercostal Space

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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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14 - Intercostal Space