Thorax Flashcards
Enlist all openings in diaphragm .
There are 3 large opening for
1) Inferior vena cava
2) oesophagus
3) aorta
Small opening include opening for
1) Superior epigastric artery
2) Musculophrenic artery
3) Lower 5 intercostal vessels and nerves
4) Subcostal vessel and nerve
5) Sympathetic trunk
6) Greater and lesser splanchnic nerve
7) Left phrenic nerve
Azygos vein
The azygos vein drains the thoracic wall and the upper
lumbar region. Important channel connecting the superior and
inferior venae cavae.
It also
connects portal venous system, caval venous system
and vertebral venous system.
Formation
1) Lumbar Azygos vein
2) Right Subcostal vein
3) Right ascending lumbar veins
Course
1 The azygos vein enters the thorax by passing through
the aortic opening of the diaphragm.
2 The azygos vein then ascends up to fourth thoracic
vertebra and drains into superior vena cava.
Tributaries of Azygos vein
1 Right superior intercostal vein formed by union of second, third and fourth posterior intercostal
veins.
2 Fifth to eleventh right posterior intercostal veins
3 Hemiazygos vein at level of lower border of 8th thoracic vertebra.
4 Accessory hemiazygos vein at level of upper border of 8th thoracic vertebra.
5 Right bronchial vein
6 Several oesophageal, mediastinal, pericardial veins
Typical intercostal space
Typical intercostal spaces are the spaces whose
intercostal nerves and vessels are confined to thoracic
wall only.
Contents
All intercostal muscles
2 anterior intercostal artery and vein
Posterior intercostal artery and vein
Intercostal nerve
Typical intercostal nerve
Upper two intercostal nerves also supply the upper limb.
The lower five intercostal nerves,
seventh to eleventh thoracic nerves, also supply
abdominal wall. These are, therefore, said to be thoracoabdominal nerves.
The remaining nerves, third to sixth,
supply only the thoracic wall; they are called typical
intercostal nerves.
Ascending aorta
Arises from upper end of left ventricle enclosed within pericardium. At the root of aorta there are three dilation called aortic sinuses. These are anterior, left and right posterior.
Right coronary artery arises from anterior aortic sinus.
Left coronary sinus arises from left posterior aortic sinus
Arch of Aorta
Begins at second sternochondral joint.
Ends at level of 4th thoracic vertebra by becoming continuous with descending aorta.
It gives brachiocephalic artery which gives right common carotid and right subclavian artery.
It also gives left common carotid artery and left subclavian artery
Descending aorta
Continuation of arch of Aorta which lies in posterior mediastinum.
Continues as abdominal aorta which ends by dividing into right and left common iliac arteries.
Begins at level of 4th thoracic vertebra. Terminates at level of 12th thoracic vertebra.
Gives nine posterior intercostal arteries on each side for 3rd to 11th intercostal space.
Subcostal artery on each side.
Two left bronchial arteries
Oesophageal branches
Pericardial branches
Mediastinal branches
Superior phernic artery
Clinical anatomy of thorax 1
1)Chest wall of child is highly elastic so there are least chances of rib fracture.
In adults , direct or indirect violence leads to fracture of ribs at the angle of rib
2) Upper 2 ribs are protected by clavicle and lower 2 ribs which are free are least commonly injured.
3) Diaphragm descends during inspiration to increase vertical diameter of thoracic cage.
4) Hiccups occurs due to spasmodic involuntary contraction of diaphragm, gastric irritation of phrenic nerve irritation.
5) A cervical rib is attached to C7 vertebra which occurs in 0.5% subjects. It can exert pressure on lower trunk of brachial plexus. Such person complains abnormal sensation along ulnar border and wasting of muscles of hand supplied by T1 segment .
6) In narrowing of aorta the posterior intercostal arteries get enlarged greatly to establish a collateral circulation.
7) Thoracic inlet syndrome - Subclavian artery and first thoracic nerve arch over first rib. These structures can be pulled or pressed by cervical rib or variation in insertion of serratus anterior. Symptoms are vascular or neural or both
8) Thoracic cavity houses heart, 2 lungs , blood vessels , nerves and lymphatic.
9) Cervical or lumbar rib may be present but only cervical rib gives symptoms.
10) Ribs are weaker at angle and vulnerable to injury at that area.
11) Apex beat lies below and medial to nipple
12) 1-7 ribs reach the sternum, 8-10 ribs reach the costal margin and 11-12 rib do not reach front at all.
Clinical anatomy of thorax 2
1) Root pain or girdle pain occurs due to irritation of intercostal nerves and pain is referred to front of chest or abdomen
2) Herpes virus can cause infection of intercostal nerves. If herpes infection is to 2nd thoracic nerve there is referred pain to upper medial side of arm.
3) Distal end of internal thoracic artery is cut and is joined to narrowed part of coronary artery.
4) Pus from vertebral column tracks around thorax along course of neurovascular bundle.
5) Cardiac pain is an ischemic pain caused due to incomplete obstruction of coronary artery. Axons of these pain fibres reach to thoracic 1 to 5 segment of spinal cord. These dorsal root ganglion also recieve impulses from medial side of arm, forearm and upper part of front of chest, the pain gets referred to these areas.
6) There are 11 intercostal spaces on back and 9 on front
7) Intercostal muscles are 3 in layers - external , internal and transverse.
8) Neurovascular bundle lies in upper part of intercostal space in between internal and innermost intercostal muscles
9) Posterior intercostal artery and it’s collateral branches supply 2/3rd of intercostal space
10) Right posterior intercostal arteries are longer than left one.
11) Accessory hemiazygos vein drains left 5-8 intercostal spaces and 9-11 intercostal spaces drain in hemiazygos vein.
Clinical anatomy of thorax 3
1) Visceral pleura of lungs is derived from splanchnopleuric mesoderm whereas parietal layer is derived from somatopleuric layer of lateral plate mesoderm.
2) Sympathetic system dilates the bronchi whereas parasympathetic system constricts the bronchial tree and is also secretory to glands.
3) Costodiaphragmatic and costomediastinal recess are 2 recesses of parietal pleura which act as reserve spaces for lungs to expand during deep inspiration.
4) Aspiration of any fluid from pleural cavity is paracentesis thoracis. It is done in eighth intercostal space in midaxillary line. Needle is passed through its lower part to avoid injury to principal neurovascular bundle.
5) Pleurisy is inflammation of pleura in which it may be dry or accompanied by collection of fluid in pleural cavity called as pleural effusion. Dry Pleurisy is more painful because during inspiration both layers come in contact and there is friction.
6) Presence of air in pleural cavity is pneumothorax.
7) Presence of blood in pleural cavity is hemothorax.
8) Hydropneumothorax is presence of both fluid and air in pleural cavity.
9) In emphysema there is presence of pus in pleural cavity.
10) Coastal and peripheral part of diaphragmatic pleura are innervated by intercostal nerves. Hence irritation of these layers causes referred pain to anterior thoracic or abdominal wall.
11) Pain on right shoulder occurs due to inflammation of gall bladder and pain on left shoulder occurs due to splenic rupture.
12) Pleural effusion causes obliteration of Costodiaphragmatic recess.
13) Parietal pleura limits the expansion of lungs and visceral pleural behaves in same way as that of lungs.
14) Parietal pleura has same blood and nerve supply as that of the thoracic wall.
15) Pleura lies beyond the thoracic cage at 5 places. Right and left cervical pleura, right and left costoverterbal angles and right xiphicostal angle.Pleura is likely to be injured at these places.
16) Paracentesis thoracis is done in lower part of intercostal space to avoid injury to intercostal vessels and nerves.
17) Pleural effusion is one of sign of tuberculosis of lungs.
