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DESCRIBE COURSE, BRANCHES AND DISTRIBUTION OF TYPICAL INTERCOSTAL NERVE (LE).
Formation:
The thoracic spinal nerve is formed by anterior and posterior roots, which arises from the anterior and posterior horns of spinal cord respectively.
The anterior and posterior roots join together to form the trunk. The trunk divides into anterior and posterior rami.
The anterior ramus forms the intercostal nerve.
Course:
The nerve passes through the respective intervertebral foramen and appears in the posterior part of the intercostal spaces.
On reaching the angle of the upper rib, the trunk of the nerve passes forwards along the costal groove between intercostalis internus and intimus muscle.
Intercostal nerves runs in the costal groove and ends near the sternum.
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In the costal groove the arrangements of structures from above downwards are
vein,artery and nerve.
Branches and distribution
Communicating branches.
ganglionic
Distributing branches.
muscular
collateral
cutaenous branches.
lateralcutaeneous
The anterior cutaeneous branch
FIRST INTERCOSTAL SPACE (SE).
The first intercostals space lies between the first and second ribs.
Bounderies:
Above
sharplower margin of the 1st rib and its cartilage.
Below
blunt upper margin of the 2nd rib and its cartilage.
Infront
lateral border of the sternum between the costal notches.
Behind
body of the 1st thoracic vertebra. Contents of the space.
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Intercostal muscles. Vessels.
Nerves. Intercostal muscles . external intercostal muscle. internal intercostal muscle. transversusthoracis muscle. Vessels.
Intercostal arteries
anterior intercostal
Posterior intercostal
Intercostals vein
anterior intercostal vein drains into internal thoracic vein. Posterior intercostal vein drains into brachio cephalic vein.
Intercostals nerve.
First intercostal nerve arises as a slender lower branch from the ventral ramus of the first thoracic nerve.
It passes between the internus muscle and the costal pleura.
The nerve runs along the under surface of the first rib,which is devoid of a costal groove.
It does not usually present collateral and lateral cutaeneous branches. Relation of structures from above downwards are nerve artery and vein.
TYPICAL INTERCOSTAL SPACES AND ITS CONTENTS (SE).
Intervenes between typical ribs and are traversed by vessels and nerves confined to the thoracic wall
3rd to 6th spaces are the typical intercostal spaces.
Boundaries
Above
sharp lower margin of the upper rib and its cartilage.
Below
Blunt upper margin of the lower rib and its cartilage.
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Infront
Lateral border of the sternum between the costal notches.
Behind
Body of the 1st t thoracic vertebra.
Characteristic features
Each space is directed downwards and forwards. Narrow towards vertebral column.
Widest part being at the costochondral junction. Posterior part of each space is inter osseous.
Anterior part intervenes between two cartilages & is intercartilagenous.
Contents.
Intercostal muscles. Vessels.
Nerves.
Intercostal muscles. external intercostal muscle. internal intercostal muscle. transversusthoracis muscle
Vessels.
Intercostal arteries
anterior intercostal
Posterior intercostals
Intercostals vein
anterior intercostals vein drains into internal thoracic vein. Posterior intercostal vein 3rd and 4thdrains into arch of azygous vein. 5th and 6th drains into vertical part of the azygous vein.
Intercostal nerve.
Relation of structures from above downwards are nerve artery and vein.
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TYPICAL INTERCOSTAL
The intercostals nerves are the anterior primary rami of thoracic one to thoracic eleven spinal nerves.
The 3rd to 6th intercostals nerves are typical intercostals nerves because they are confined to the thoracic wall.
Course:
Intercostals nerve runs in the costal groove and ends near the sternum.
Relations:
Each nerve passes below the neck of the rib of the number and enters the costal groove. The relation of the structures in the costal groove from above downwards is posterior intercostals vein,artery and nerve (VAN).
In the greater part of the space ,the nerve lies between the intercostalis intimi and internal intercostal muscle.
In the anterior part it pierces the internal intercostals muscle,the external intercostals membrane and the pectoralis major muscle as the anterior cutaeneous nerve.
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Branches
Communicating branches.
Ganglionic
Distributing branches.
Muscular
Collateral
Cutaenous branches.
Lateralcutaeneous
The anterior cutaeneous branch
INTERNAL THORACIC ARTERY (SE)
Origin
Internal thoracic artery arises from lower border of 1st part of subclavian artery opposite the thyrocervical trunk.
Course and termination
It descends medially and downwards behind sternal end of clavicle,and1st costal cartilage.
Runs vertically downwards 2cm fron lateral border of sternum till 6th intercostals space.
It ends by divding into two terminal branches.
Relations
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Infront:
Upper six intercostals spaces and their muscles.
Crossed by the terminations of upper six intercostals nerves.
Posteriorly
The endothoracic fascia & pleura up to the 2nd or 3rd costal cartilage. Below that level it is covered by the transverses muscle.
Branches
Thepericardio phrenic artery. mediastinal arteries
Two anterior intercostal arteries in each intercostal space. perforating branches.
superior epigastric artery. musculophrenic artery.
MENTION NAME OF STRUCTURES IN ORDER IN THE ITERCOSTAL GROOVE(SA) The structures in the intercostals groove from above downwards are
Intercostal Vein .
Intercostal Artery.
Intercostal Nerve.
Intercostal vein
anterior intercostals vein drains into internal thoracic vein. Posterior intercostal veins drain into the azygos vein.
Intercostal arteries
anterior intercostal
Posterior intercostals
Intercostal nerve
Each nerve is the ventral ramus of thoracic spinal nerve.
Intercostals vein
anterior intercostals vein drains into internal thoracic vein. Posterior intercostal vein 3rd and 4thdrains into arch of azygous vein, 5th and 6th drains into vertical part of the azygous vein.
Intercostal arteries
anterior intercostal
Posterior intercostals
Intercostal nerve
Each nerve is the ventral ramus of thoracic spinal nerve.
ANTERIOR INTERCOSTAL MEMBRANE (SA)
Anterior intercostal membrane is an aponeurosis of the external intercostalsmuscle,present in the intercartilagenous part.
It is also known as external intercostals membrane.
The neurovascular bundle runs forwards in the costal groove ,first between the pllura and internal intercostals membrane and then between the internal intercostals and intercostalisintimi muscle.
The typical thoracic spinal nerve pierces this membrane and terminates as the anterior cutaneous nerve of thorax.
EXTERNAL INTERCOSTAL MUSCLE (SA)
Origin:
lower border of rib.
Insertion:
upper border of rib below origin.
The direction of the fibres of the external intercostals muscle is downwards,forwards and medially
Replaced anteriorly by external intercostal membrane.
Nerve supply: Intercostal nerve.
Action:
Elevate ribs in forced inspiration
TYPICAL INTERCOSTAL NERVE (SA)
The 3rd to 6th intercostals nerves are typical intercostals nerves because they are confined to the thoracic wall.
Formation:
The thoracic spinal nerve is formed by anterior and posterior roots,which arises from the anterior and posterior horn of spinal cord respectively.
The anterior and posterior roots join together to form the trunk. The trunk divides into anterior and posterior rami.
The anterior ramus forms the intercostal nerve.
Branches: communicating branches.
ganglionic branches. distributing branches. muscular branches. collateral branches
cutaenous branches. lateralcutaeneous nerve. anterior cutaeneous branch
SUPERIOR INTERCOSTAL ARTERY (SA)
Superior intercostal artery is the branch from the costocervical trunk of the subclavian artery.
The first two posterior intercostals arteries arises from this artery.
The superior intercostals artery passes over the anterior surface of the neck of the first rib.
The artery is related to following structures from mediolaterally,beneath the pleura,sympathetictrunk,first posterior intercostalsvein,and the ascending branch of ventral ramus of first thoracic nerve.
BRANCHES OF THE INTERNAL THORACIC ARTERY (SA)
Thepericardio phrenic artery.
The mediastinal arteries
Two anterior intercostal arteries in each intercostal space.
The perforating branches.
The superior epigastric artery.
The musculophrnic artery
NAME THE TERMINAL BRANCHES OF INTERNAL MAMMARY ARTERY (SA)
The terminal branches of the internal mammary artery are
Themusculophrenic artery.
The superior epigastric artery.
The musculophrenic artery
It gives two anterioir intercostal branches to each of 7th to9th intercostal spaces.
It pierces the diaphragm and supplies it.
The superior epigastric artery.
It enters the rectus sheethand anastomoses with the inferior epigastric artery.
AZYGOS SYSTEM OF VEINS- DEFINITION, LABELLED DIAGRAM, APPLIED ANATOMY (SE)
Definition:
The term azygos means unpaired. (in Greek zygo – pair)
Azygos system of veins includes veins which are unpaired, straight in course, paravertebral in position and drains blood from back, thoracic & abdominal walls. consists of azygos vein, hemiazygos vein & accessory hemiazygos vein.
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Applied anatomy:
In case of Superior venae cava or Inferior venae cava obstruction azygos vein provides an important collateral pathway for venous
return to the heart
Lobe of azygos vein- sometimes medial part of superior lobe is partially separated by a fissure which contains arch of azygos vein
AZYGOS VEIN (SE)
The term azygos means unpaired (in Greek zygo – pair)
It is present only on right side in upper part of posterior abdominal wall and posterior mediatinum
It is provided with valves
It drains venous blood from thoracic wall & upper lumbar region It connects Superior venae cava and Inferior venae cava
Formation:
Is formed in one of the following ways
arises as lumbar azygos vein from the posterior aspect of Inferior venae cava or
formed by union of right subcostal & right ascending lumbar vein or
as a continuation of right subcostal vein
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Course:
ascends in front of lumbar vertebra
enters thoracic cavity by piercing right crus of diaphragm or passing through aortic opening of diaphragm
ascends upto 4th thoracic vertebra , arches forward forming arch of azygos vein
Termination:
Arch of azygos vein opens into Superior venae cava
Tributaries:
Trunk formed by union of right ascending lumbar vein & right subcostal vein Right superior intercostal vein formed by union of 2nd, 3rd, 4th right posterior intercostal vein
5th to 11th right posterior intercostal veins AccessoryHemiazygos vein
Hemiazygos vein
Applied anatomy:
In case of SVC or IVC obstruction azygos vein provides an important collateral pathway for venous
return to the heart
Lobe of azygos vein- sometimes medial part of superior lobe is partially separated by a fissure which
contains arch of azygos vein .
AZYGOS VEIN – LEVEL, FORMATION, TERMINATION AND TRIBUTARIES (SA)
It is an unpaired vein present only on right side in upper part of posterior abdominal wall, posterior mediatinum
Formation:
Is formed by the union of lumbar azygos, right subcostal & right ascending lumbar vein
Termination:
Arch of azygos vein opens into Superior venae cava
Tributaries:
Right superior intercostal vein
5th to 11th right posterior intercostal veins Accessory Hemiazygos vein Hemiazygos vein
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