oesophagus, trachea and great vessels of...
TRANSCRIPT
Oesophagus, Trachea and Great vessels of Thorax
Dr. Ifeanacho
ABIREH MBBS, MSc, PGDE, MWACS
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Introduction -Mediastinum
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OESOPHAGUS A muscular tube 25 cm in length Begins at the lower border of the cricoid
cartilage (C6) Passes through the diaphragm at T10 Ends in the abdomen at the cardiac orifice of
the stomach at T11 Has cervical, thoracic and abdominal parts 7/8/2019 www.abireh.com 3
Oesophagus -parts Cervical portion Begins in the midline in front of the
prevertebral fascia Inclines to the left Enters the thoracic inlet
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Oesophagus -parts
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Oesophagus -parts
Thoracic portion Passes downwards through the superior
mediastinum Returns to midline at T5 Deviates to the left again at T7 Curves forward to pass in front of the
descending thoracic aorta
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Oesophagus -parts
Pierce the diaphragm 2.5 cm to the left of the midline at 7th left costal cartilage
Here fibres from the right crus of the diaphragm sweep around the oesophageal opening in a sling-like loop
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Oesophagus -parts
Abdominal portion 1-2cm Length depends on muscle tone and degree
of distension of the stomach
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Oesophagus -Relations Superior mediastinum It is crossed by the arch of the aorta on its left,
and vena azygos on its right Trachea lies anteriorly
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Oesophagus -Relations
Posterior mediastinum Anterior Left main bronchus and the right pulmonary
artery Pericardium and the posterior sloping fibres
of the diaphragm Posterior Thoracic duct 7/8/2019 www.abireh.com 10
Oesophagus -Relations
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Oesophagus -Relations
Thoracic duct lies at first, to its right, then behind and to its left in the superior mediastinum
Hemiazygos, accessory hemiazygos and right posterior (aortic) intercostal arteries
Mediastinal pleura touches the oesophagus on both sides
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Oesophagus -Constrictions Cricopharyngeal sphincter Narrowest part of the oesophagus Commencement of the oesophagus 15 cm from the incisor teeth Aortic arch 22 cm from incisor
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Oesophagus -Constrictions
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Oesophagus -Constrictions
Left principal bronchus 27 cm from incisor Opening in the diaphragm 38 cm from the incisor teeth Left atrium Causes indentation when enlarged
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Oesophagus –Arterial supply Upper part -Inferior thyroid arteries Middle part Oesophageal branches from aorta Bronchial arteries Lower part -Oesophageal branches of left
gastric artery
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Oesophagus –Venous drainage Upper part -Brachiocephalic veins Middle part -Azygos system of veins Lower part-Oesophageal tributaries of left
gastric vein (empties into portal vein There is an anastomosis between portal and
systemic venous systems in this lower part It lies at T8 (level with the central tendon) (T8
vertebra)
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Oesophagus -Lymphatics Cervical part -Deep cervical nodes Thoracic part -Tracheobronchial and
posterior mediastinal nodes Abdominal part -left gastric and coeliac nodes There exist lymphatic channels within the
wall of the oesophagus So drainage from any given area does not
strictly follow the above pattern
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Oesophagus -Nerve supply Upper part -Recurrent laryngeal nerves Sympathetic fibres from cell bodies in the
middle cervical ganglia Middle and lower parts -fibres from thoracic
sympathetic trunks and greater splanchnic nerves
Parasympathetic from the vagus nerves
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Oesophagus -Nerve supply
Motor supply Vagus From cell bodies in the nucleus
ambiguous for the upper striated muscle part From the dorsal motor nucleus with
relay in plexuses in the wall for the lower visceral muscle part
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Oesophagus -Nerve supply
Secretomotor fibres from the vagus
Pain fibres run with the vagal and sympathetic supply
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TRACHEA It is the continuation of the larynx It is 10 cm long and 2 cm wide 3mm wide in first year of life Equal in mm to age in years Starts below the cricoid cartilage at C6 5 cm above jugular notch
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Trachea It enters thoracic inlet in the midline Passes downwards and backwards behind the
manubrium Bifurcate into two principal (main) bronchi at
T5 May stretch up o 15cm in full inspiration Then bifurcation descends to the level of T6
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Trachea -Parts Cervical part This is 5 cm long From cricoid cartilage to the jugular notch This part lies in the midline in contact with
front of the oesophagus Recurrent laryngeal nerve runs in the groove
between trachea and oesophagus
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Trachea -Parts
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Trachea -Parts
Carotid sheath and lobes of thyroid gland lie to the side
Isthmus of the thyroid gland is adherent to 2nd , 3rd and 4th tracheal rings
Inferior thyroid veins and anterior jugular venous arch lie in front
Thyroidea ima artery and the upper end thymus also lie anterior
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Trachea -Parts Thoracic part This runs through the superior mediastinum in
front of the oesophagus Anterior relations Manubrium with sternohyoid and sternothyroid
muscles attached Thymus (remnants) Inferior thyroid and left brachiocephalic veins Brachiocephalic and left common carotid
arteries
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Trachea -Relations
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Trachea -Relations
Lateral relations -right Right vagus Right lung and pleura Arch of the azygos vein Right brachiocephalic vein Superior vena cava
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Trachea -Relations
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Trachea -Relations
Lateral relations – left Left common carotid and subclavian arteries Pleura Left vagus nerve Arch of the aorta (curves backwards over the
left bronchus) Left recurrent laryngeal nerve
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Trachea -Relations
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Trachea –Blood supply Branches of inferior thyroid and
bronchial arteries Veins drain to inferior thyroid vein
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Trachea -Lymphatics Pre- and paratracheal nodes Inferior deep cervical nodes
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Trachea –Nerve supply Mucous membrane Afferent fibres -Vagi and recurrent laryngeal
nerves Smooth muscles and blood vessels Sympathetic fibres from upper ganglia of the
sympathetic trunks
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Trachea –Nerve supply
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Trachea -Function The rings keep the airway open Mucus traps particles Cilia clears debris (by beating upwards) Glandular secretion helps to humidify
air
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Trachea -Function
During swallowing the trachea is stretched as the larynx moves upwards
ut the bifurcation does not move Elasticity restores the normal position The trachealis muscle controls the diameter of
the tube
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Trachea -Function
During coughing there is a 30% increase in transverse diameter
Produced by compressed air in the trachea while the vocal cords are shut
The trachea narrows to 10% less than the resting diameter at the instant the cords open
This increases the explosive force of the blast of compressed air
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GREAT VESSELS -THORAX These vessels carry blood to and from the
heart They include: Aorta Pulmonary trunk Superior vena cava Inferior vena cava
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Aorta The thoracic portion can be divided into: Ascending aorta Arch of aorta Descending (Thoracic aorta) Only the arch of the aorta is in the superior
mediastinum
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Aorta
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Ascending aorta The ascending aorta emerges from the
pericardium Then approaches the manubrium And becomes arch of aorta at the level of
manubriosternal joint T4/5
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Arch of aorta The arch of aorta passes backwards over the
left bronchus to reach the body of T4 to the left of the midline
The arch is initially anterior and finally lateral to the trachea
Three branches arise from the superior border of the arch of the aorta
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Arch of aorta
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Arch of aorta -Relations Phrenic and vagus nerves crosses on its left
side Phrenic nerve passes in front of root of the
lung Vagus nerve passes behind the root of the
lung Sympathetic and vagus branches to the
superficial part of the cardiac plexus lie between the phrenic and vagus nerve
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Arch of aorta -Relations
Left superior intercostal vein passes across the arch deep to the phrenic nerve
Left recurrent laryngeal nerve hooks around the ligamentum arteriosum to pass upwards on the right side
The pulmonary trunk bifurcates into right and left pulmonary arteries in the concavity of the arch
The trachea and oesophagus lie on the right
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Arch of aorta -Relations
The adventitial layer of the arch contains baroreceptors innervated by vagal nerve fibres, which are concerned with the reflex control of the heart rate
Aortic bodies lie under the arch (around the ligamentum arteriosum)
Supplied by vagal fibres Chemoreceptors concerned with respiratory
reflexes
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Arch of aorta -Branches Brachiocephalic trunk Left common carotid Left subclavian arteries At their origins, all three are crossed
anteriorly by the left brachiocephalic vein
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Arch of aorta -Branches
Brachiocephalic trunk (First branch) Largest of the three branches At origin it lies behind the manubrium It is slightly anterior to the other two
branches It ascends slightly posteriorly and to the right
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Arch of aorta -Branches
The brachiocephalic trunk divides at right sternoclavicular joint into:
Right common carotid artery Right subclavian artery The arteries mainly supply the right side of
the head and neck and the right upper limb, respectively
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Arch of aorta -Branches
Thyroidea ima artery is a branch of brachiocephalic trunk seen occasionaly
Supply the thyroid gland
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Arch of aorta -Branches
Left common carotid artery (2nd branch) It arises from the arch just to the left and
posterior to the brachiocephalic trunk Ascends through the superior mediastinum
along the left side of the trachea Supplies the left side of the head and neck
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Arch of aorta -Branches
Left subclavian artery (3rd branch) It arises from the arch of aorta just to the left
posterior to the left common carotid artery Ascends through the superior mediastinum
along the left side of the trachea Supplies the left upper limb
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Thoracic aorta Begins at the lower edge of vertebra T4 As continuation of the arch of aorta It ends at lower edge of T12 It passes through the aortic hiatus posterior to
the diaphragm at T12 It lies directly anterior to the lower thoracic
vertebral bodies
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Thoracic aorta -Branches
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Thoracic aorta -Branches
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Superior vena cava Formed by confluence of the two
brachiocephalic veins At lower border of 1st right costal cartilage It passes vertically downwards behind the
right border of the sternum Pierces the pericardium at 2nd costal cartilage Enters the upper border of the right atrium at
3rd right costal cartilage
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Superior vena cava
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Superior vena cava
Azygos vein at level of sternal angle There are no valves in the superior vena cava,
brachiocephalic veins or the azygos system of veins
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Superior vena cava
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Pulmonary trunk Contained within the pericardial sac It is covered by the visceral layer of serous
pericardium Lies in a common sheath with the ascending
aorta
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Pulmonary trunk
It arises from the conus arteriosus of the right ventricle
Slightly anterior to aortic orifice Ascends, moving posteriorly and to the left,
lying initially anterior and then to the left of the ascending aorta
Divides at T5/6, posterior to 3rd left costal cartilage
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Pulmonary trunk
Right pulmonary artery Passes to the right, posterior to the ascending
aorta and the superior vena cava, to enter the right lung
left pulmonary artery Passes inferiorly to the arch of the aorta and
anteriorly to the descending aorta to enter the left lung
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Pulmonary trunk
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Inferior vena cava Passes through the diaphragm at T8 It enters the fibrous pericardium A short portion lies within the pericardial sac
before entering the right atrium While within the pericardial sac, it is covered
by serous pericardium except for a small portion of its posterior surface
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Inferior vena cava
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Pulmonary vein A very short segment of each pulmonary vein
lie within the pericardial sac Usually two from each lung Pass through the fibrous pericardium and
enter the superior region of the left atrium on its posterior surface
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Pulmonary vein
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Pulmonary vein
In the pericardial sac, all but a portion of the posterior surface of these veins is covered by serous pericardium
The oblique pericardial sinus is between the right and left pulmonary veins, within the pericardial sac
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Ligamentum arteriosum Ligamentum arteriosum is the obliterated
ductus arteriosus Ductus arteriosus connects the pulmonary
trunk with the arch of aorta and allows blood to bypass the lungs during development
Ductus arteriosus closes soon after birth and forms the ligamentous connection observed in the adult
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Ligamentum arteriosum
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Azygos system of veins
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Diaphragmatic openings
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Thank you for listening
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