04 Thoracic Cavity. Mediastinum. Thymus. Pleura.
cervical pleura
-extends through the superior thoracic aperture into the root of the neck -forms a cup-shaped pleural dome over the apex of the lung
anterior and posterior intercostal, superior phrenic and mediastinal arteries.
Arteries of the parietal layer
bronchial arteries
Arteries of the visceral layer
a deep infection of the neck; penetrating wounds of the chest; esophageal perforations. Air can escape into the connective tissue spaces and ascends beneath the fascia to the root of the neck, producing subcutaneous emphysema.
Causes of Mediastinitis
Median partition - the mediastinum. Lateral partitions - pleural sacs with lungs. The cavity is lined with the endothoracic fascia.
Cavities within the thoracic cavity
the cervical pleura extends up into the neck, covered by the suprapleural membrane; reaches a level 2.5 cm above the medial third of the clavicle;
Cervical pleurae boundaries and features
decreased lung expansion on the side of the effusion, with decreased breath sounds and dullness on percussion over the effusion.
Clinical signs of a pleural effusion
lines the inner surfaces of the thoracic wall, except the front of the vertebral bodies
Costal pleura boundaries
diaphragmatic pleura
Covers superior surface of diaphragm
covers the thoracic surface of the diaphragm
Diaphragmatic pleura area
Each pleural sac has a visceral and a parietal layer, separated by the slitlike pleural cavity containing 5-10ml of fluid The two layers become continuous with one another at the hilum of each lung. To allow for movement of the pulmonary vessels and large bronchi during respiration, the pleural cuff hangs down as a loose fold called the pulmonary ligament.
Features of the Pleurae including layers
in front - the body of the sternum; behind - the lower 8 thoracic vertebrae.
Inferior Mediastinum borders
thymus, heart, pericardium, phrenic nerves, esophagus, vagi nerves, thoracic duct, descending aorta, azygos and hemiazygos veins, sympathetic trunks.
Inferior mediastinum contents
receives an autonomic nerve supply from the pulmonary plexus
Innervation of the visceral pleura (stretch only)
intercostal nerves
Innervations to pain, temperature, touch and pressure of the parietal costal pleura
phrenic nerve and lower 6 intercostal nerves around the periphery
Innervations to pain, temperature, touch and pressure of the parietal diaphragmatic pleura
Phrenic nerve
Innervations to pain, temperature, touch and pressure of the parietal mediastinal pleura
parasternal and internal intercostal lymph nodes near the heads of the ribs
Lymph drainage of the parietal pleura
Lung cancer typically involves the mediastinal lymph nodes, which on enlargement may compress the left recurrent laryngeal nerve, producing paralysis of the left vocal fold. An expanding cyst or tumor can partially occlude the superior vena cava, causing severe congestion of the veins of the upper part of the body. Other pressure effects can be seen on the sympathetic trunks, phrenic nerves, and sometimes the trachea, main bronchi, and esophagus.
Mediastinal tumors or cysts presentations
costal pleura
Parietal pleura attached to ribs.
sternal angle
Ridge between manubrium and body at second rib
costomediastinal recess
Small space of the pleural cavity near heart
costomediastinal recess
Space where the left costal and mediastinal parietal pleura meet and leave a space for the cardiac notch of the left lung (occupied by the lingula during inspiration)
The mediastinum is divided into superior and inferior mediastina. The inferior mediastinum is subdivided into the middle mediastinum; the anterior mediastinum; the posterior mediastinum.
Subdivisions of the Mediastina
in front - the manubrium sterni; behind - upper 4 thoracic vertebrae.
Superior Mediastina Borders
thymus, large arteries and veins, phrenic and vagi nerves, trachea, esophagus, thoracic duct, and sympathetic trunks.
Superior Mediastinum Contents
The approach is performed by dividing the sternum down the middle of the chest. The manubrium should be completely divided and the sternotomy is carried to the level of the 3rd or 4th intercostal space. performed as a part of an access to the heart and great vessels in the neonatal period; for the treatment of thymomas, primary thymic lymphomas and myasthenia gravis. The biopsy may be necessary primary to the removal.
Thymectomy procedure overview
inferior thyroid, internal thoracic, mediastinal arteries.
Thymus blood supply
exceedingly minute branches of the vagi and sympathetic trunk reach the gland; the branches are vasomotor.
Thymus innervation
- lies in the superior and anterior inferior mediastinum within area interpleuralis superior; - in superior mediastinum it is related to the manubrium sterni in front and to the large vessels behind; - in inferior anterior mediastinum it is related to the body of sternum in front and to the pericardium behind; - has 2 lobes of pinkish-gray color, each surrounded by fibrous capsule; - the septae of the capsule separate the lobes of the gland into the lobules.
Thymus locations and relative communicating structures
In the newborn infant, it reaches its largest size relative to the size of the body; it may extend up through the superior mediastinum in front of the great vessels into the root of the neck. The thymus continues to grow until puberty but thereafter undergoes involution.
Thymus relative size at birth and development
The tube is inserted in the 4th or 5th intercostal space along the anterior axillary line. The chest tube allows for continuous, large volume drainage until the underlying pathology can be more formally addressed.
Tube thoracostomy placement and purpose
Parietal layer: anterior and posterior intercostal, superior phrenic and mediastinal veins. Visceral Layer: bronchial veins
Venous drainage of the pleurae
true thymic hyperplasia (idiopathic, associated with the use of steroids, rebound to chemotherapy, radiation, burns or other severe systemic stress); lymphoid hyperplasia (lymphoid follicular hyperplasia or autoimmune thymitis). Both manifest as diffuse symmetric enlargement of the thymus.
What are causes of and what is thymic hyperplasia?
• thymomas are found in 10-15% of patients with myasthenia gravis; • symptoms are sometimes confused with bronchitis because of compression of the recurrent laryngeal nerve; • all thymomas are potentially cancerous; • treatment of thymomas often requires complete thymectomy.
What are some of the general features associated with Thymomas
thoracic outlet and the root of the neck, the diaphragm, the sternum and the vertebral column.
What are the Mediastinum Borders
the thymus, the heart and large blood vessels, the trachea and esophagus, the thoracic duct and lymph nodes, the vagus and phrenic nerves, and the sympathetic trunks.
What are the Mediastinum contents
slitlike spaces between the costal and diaphragmatic parietal pleura.
What are the costodiaphragmatic recesses?
pleural surfaces becoming coated with inflammatory exudate, causing the surfaces to be roughened; - this produces friction; - a pleural rub can be heard with the stethoscope on inspiration and expiration; - the exudate becomes invaded by fibroblasts, which lay down collagen and bind the visceral pleura to the parietal pleura, forming pleural adhesions.
What causes pleurisy?
a collection of pus in the pleural cavity
What is Empyema
- it is a diagnostic procedure for obtaining of specimens of tracheobronchial lymph nodes; - a small incision is made in the midline just above the suprasternal notch; - the superior mediastinum is explored down to the region of the bifurcation of the trachea.
What is Mediastinoscopy and how is it performed
air in the pleural cavity associated with serous fluid.
What is a hydropneumothorax?
abnormal accumulation of serous fluid in the pleural cavity (300 ml is sufficient for its clinical detection).
What is a pleural effusion
air in the pleural cavity
What is a pneumothorax?
air enters the pleural cavity suddenly without its cause being immediately apparent
What is a spontaneous pneumothorax?
air enters on inspiration but cannot exit through the wound; air pressure builds up on the wounded side and pushes the mediastinum toward the opposite side; opposite lung is compressed by the deflected mediastinum
What is a tension pneumothorax?
Thoracocentesis (pleural puncture) is performed in purposes of diagnostics and treatment of pneumothorax and pleural effusions. For evacuation of effusion: the 7th or 8th intercostal space between midaxillary and scapular lines along the upper edge of the lower rib. For evacuation of air: the 2nd or 3rd intercostal space along midclavicular line.
What is a thoracocentesis and how is it performed for effusion? air?
pleural cavity is open to the outside air
What is an open pneumothorax?
lymph in the pleural cavity.
What is chylothorax?
air associated with blood
What is hemopneumothorax?
inflammation of the pleura, secondary to inflammation of the lung (e.g., pneumonia);
What is pleurisy (pleuritis)?
air associated with pus.
What is pyopneumothorax?
Failure of thymic development DiGeorge syndrome, also known as 22q11.2 deletion syndrome, is the most common cause of thymic aplasia in humans. Patients may present with a profound immunodeficiency disease, due to the lack of T cells.
What is thymic aplasia and most common cause?
air was purposely injected into the pleural cavity to collapse and rest the lung (artificial pneumothorax)
What was the old treatment for tuberculosis?
mainly for myasthenia gravis treatment. A 1,5 - inch incision at the bottom of the neck, just above the sternum. No bone is divided and only the skin is cut.
When is transcervical thymectomy typically performed
situated along the anterior margins of the pleura.
Where are the costomediastinal recesses?
The formation of the fluid results from hydrostatic and osmotic pressures. It is secreted from capillaries of the parietal pleura to the pleural cavity, and, than absorbed into the capillaries of the visceral pleura.
Where does pleural fluid originate and where is it absorbed?
azygos vein
a vessel that drains blood from the chest wall and empties into the superior vena cava
anterior mediastinum
between pericardium and sternum contains loose CT, fat, lymphatic vessels, some vasculature
middle mediastinum
contains the heart, roots of great vessels, and pericardium
pulmonary ligament
continuation of the parietal and visceral pleurae that extend inferiorly from the root of the lung between the lung and mediastinum
mediastinal parietal pleura
covers lateral aspect of mediastinum and organs separating the pulmonary cavities and their pleural sacs. It is continuous with the visceral pleura at the hilum of the lung
subclavian artery
either of the arteries that carry blood into the arms
phrenic nerve
innervates the diaphragm
sympathetic trunk
lies to either side of the vertebral column
lymphatic vessels penetrate into the lung parenchyma to join the bronchial lymph vessels
lymph drainage of the visceral pleura
thymus gland
lymphoid organ in the mediastinum that conditions T cells to react to foreign cells and aids in the immune response
covers and forms the lateral boundary of the mediastinum.
mediastinal pleura boundaries
mediastinal pleura
parietal pleural lining covering the mediastinum
posterior mediastinum
posterior to the pericardium and diaphragm Contains the thoracic aorta, esophagus, veins, lymphatic structures, nerves (vagus, phrenic, thoracic sympathetic trunk)
costodiaphragmatic recess
potential space; when it abnormally fills with air or fluid, it compromises lung expansion
thyroid gland
produces hormones that regulate metabolism, body heat, and bone growth
common carotid artery
supplies right side of head and neck
posterior intercostal arteries
supply the vertebrae, spinal cord, intercostal muscles, and deep muscles of the back
visceral pleura
the inner layer of pleura that surrounds each lung
vagus nerve
the tenth cranial nerve that innervates digestive organs, heart and other areas
suprapleural membrane
thickening of endothoracic fascia over cervical pleura
pariental pleura
thin membrane covering the surface of the chest wall, medistinum, and diaphragm that is continuous with the visceral pleura around the lung hilum
