The Thorax Flashcards
State the functions of the thoracic cage
- Protection: Bony cage around the vital organs
2. Respiratory movements: changes in thoracic volume underlie movement of fresh air into lungs and stake air out
The thoracic cage is formed posteriorly by what part of the vertebral column?
The 12 thoracic vertebrae part of the vertebral column
The thoracic cage is formed anteriorly by what?
The stern and costal cartilages
How many processes make up the sternum and what are they called?
3 processes make up the sternum:
- The manubrium
- The body
- The Xiphoid process
What is the sternal angle?
The line separating the manubrium and body in the sternum
Why is the sternal angle an important clinical feature?
The sternal angle is an important bony landmark at the T4 or 5 vertebral level.
It indicates the manubriosternal junction and the level of the second costal cartilages
It is a reference point in counting ribs.
If you were to cut horizontally from the sternal angle you would find the:
T4 or 5 vertebral
2nd rib articulates here
The aortic arch
Azygous vein
Left recurrent laryngeal nerve
Bifurcation of the pulmonary trunk
Bifurcation of the trachea
What 2 categories can the ribs be split into?
Typical ribs
Atypical ribs
What is the 5th rib articulated to?
The vertebral column posteriorly
Sternum column anteriorly
What are the 2 functions of the costa cartilage?
- extend the ribs into forward motion
- the cartilage also contributes to elasticity within the walls of the thorax allowing the chest to expand during respiration
Which is the lowest rib that forms part of the costal margin?
The 7th rib
Which ribs fall under the typical category?
Ribs 3-9
What makes a rib “typical” ?
Typical ribs are ribs with typical (similar) features
The typical rib consists of a head, neck and body
Describe the head of a typical ribs
The head is wedge shaped and has two articular facets separated by a wedge of bone. One facet articulates with the numerically corresponding vertebrae, and the other articulates with the vertebrae above.
Describe the neck of a typical ribs
The neck of a typical rib contains no bony prominences, but simply connects the head with the body. Where the neck meets the body there is a roughed tubercle, with a facet for articulation with the transverse process of the corresponding vertebrae.
Describe the body of a typical ribs
The body, or shaft of the rib is flat and curved. The internal surface of the shaft has a groove for the neurovascular supply of the thorax, protecting the vessels and nerves from damage
Which ribs fall under the atypical category?
Ribs 1, 2, 10, 11 and 12
What makes rib 1 atypical
Rib 1 is shorter and wider than the other ribs.
It only has one facet on its head for articulation with its corresponding vertebrae (there isn’t a thoracic vertebrae above it).
The superior surface is marked by two grooves, which make way for the subclavian vessels.
What makes rib 2 atypical
Rib 2 is thinner and longer than rib 1,
Has two articular facets on the head as normal.
It has a roughened area on its upper surface, where the serratus anterior muscle attaches.
What makes rib 10 atypical
Rib 10 only has one facet – for articulation with its numerically corresponding vertebrae
What makes rib 11 and 12 atypical
Ribs 11 and 12 have no neck, and only contain one facet, which is for articulation with their corresponding vertebrae
How do structures pass through the diaphragm?
They pass through a number of apertures associated with the diaphragm.
Why do structures need to pass through the diaphragm
In order to pass between the thoracic and abdominal cavities
Which structures pass through the aortic opening?
Aorta
Thoracic duct Azygos vein
Which structures pass through the oesophageal opening?
Oesophagus
Vagus nerves,
Oesophageal branches of the gastric vessels
Lymphatics
Which structures pass through the vena caval opening?
Inferior vena cava
Right phrenic nerve
Which structures pass through the diaphragm?
Sympathetic trunk Left phrenic nerve Superior epigastric artery Aorta Thoracic duct Azygos vein Oesophagus Vagus nerves Oesophageal branches of the gastric vessels Lymphatics Inferior vena cava Right phrenic nerve
Which nerve innervates the diaphragm and from which spinal roots does this nerve originate?
Innervated from a phrenic nerve
Each phrenic nerve is formed in the neck within the cervical plexus and contains spinal roots C3-C5
What can the thoracic cavity be divided into?
The thoracic cavity can be divided into the left and right pleural cavities on both sides of the mediastinum
What are the 2 layers that make up the pleura?
- Visceral Layer
2. Parietal Layer
What does the Visceral Layer cover?
It lines the lungs
What does the Parietal Layer cover?
It lines the rib cage, diaphragm, and mediastinal structures.
What lies between the lungs?
The mediastinum
What is the mediastinum divided into?
The the superior mediastinum
The inferior mediastinum
What separates the superior mediastinum from the inferior mediastinum?
A horizontal plane passing through the sternal angle and the lower border of the 4th thoracic vertebra
What is the inferior mediastinum divided into?
- The anterior mediastinum
- The middle mediastinum
- The posterior mediastinum.
What is the mediastinum covered by?
By the mediastinal parietal pleura.
Where is the only place the mediastinum isn’t lined by mediastinal parietal pleura?
At the lung roots, where structures pass between the mediastinum and the lungs
What are the contents of the superior mediastinum?
The great vessels (the aorta, pulmonary trunk and the superior vena cava) Thymus Trachea Oesophagus Vagus nerves Phrenic nerves Left recurrent laryngeal branch of the vagus nerve Thoracic duct
What is the function of the thymus in children?
The thymus is an important part of your child’s lymphatic system.
Tthe thymus is instrumental in the production and maturation of T-lymphocytes (T cells)
The thymus produces and secretes thymosin, a hormone necessary for T cell development and production.
How does the structure of the thymus change with advancing age?
It is at its largest in children.
Once you reach puberty, the thymus starts to slowly shrink and become replaced by fat and by adipose tissue
Where is the anterior mediastinum found?
The anterior mediastinum is the area between the posterior aspect of the sternal body and the anterior aspect of the pericardium
What does the anterior mediastinum contain?
It contains the ligaments binding the fibrous pericardium to the posterior aspect of the sternum with one or two lymph nodes and small vessels.
What borders the anterior mediastinum laterally?
The mediastinal pleura
What borders the anterior mediastinum inferiorly?
The diaphragm
What does the middle mediastinum compromise of?
the pericardium the heart Also includes: the pulmonary trunk the two bronchi the ascending aorta the terminal part of the superior vena cava
What borders the posterior mediastinum anteriorly?
The posterior aspect of the fibrous pericardium
What borders the posterior mediastinum posteriorly?
The anterior surface of the thoracic vertebral bodies T4- T12.
What borders the posterior mediastinum laterally?
It is bounded by mediastinal parietal pleura
What are the principal contents of the posterior mediastinum?
Thoracic aorta and its branches Oesophagus Thoracic duct Azygos and Hemiazygos veins Lymph nodes Thoracic splanchnic nerves Sympathetic trunks
What is the function of the oesophagus?
The esophagus is a tube that connects the throat and the stomach.
It allows food and drink to travel along it to make it to the stomach
What is the function of the descending aorta?
It supplies blood to the esophagus, lungs, and the chest area, including the ribs and mammary glands
What are the 6 branches of the decending aorta?
- bronchial arteries (found in the thorax)
- mediastinal arteries (found in the thorax)
- oesophageal arteries
- pericardial arteries
- superior phrenic artery
- intercostal arteries. (found in the thorax)
Which 3 branches of the descending aorta are found in the thorax?
- The bronchial arteries
- The mediastinal arteries
- The intercostal arteries
From where does the azygous vein enter the thorax from?
Through the aortic opening