2- Thoracic cage

Question 1

How many pairs of ribs are there?

Answer 1

There are 12 pairs of ribs.

Question 2

What are the characteristics of the “true” ribs?

Answer 2

Ribs 1-7 are considered “true” ribs as they connect to the sternum via their costal cartilages.

Question 3

How do the “false” ribs differ from the true ribs?

Answer 3

Ribs 8-10 are considered “false” ribs as they articulate with their costal cartilages and do not directly connect to the sternum.

Question 4

What are the characteristics of the “floating” ribs?

Answer 4

Ribs 11 and 12 are called “floating ribs” because they do not have any anterior articulation.

Question 5

What are the components of a typical rib?

Answer 5

A typical rib consists of a head with two articular facets, a neck for attachment to the costotransverse ligament, a tubercle with a facet for articulation with the corresponding vertebra, and a flattened shaft with an angle marking the lateral limit of attachment for the erector spinae muscles. The shaft also possesses a subcostal groove for vessels and nerves.

Question 6

What are the characteristics of the first rib?

Answer 6

The first rib is the shortest, flattest, and most curved rib. It has a prominent tubercle on the inner border of its upper surface for the insertion of the scalenus anterior muscle. The subclavian vein crosses the rib in front of the scalene tubercle, while the subclavian artery and the lowest trunk of the brachial plexus are related to the rib in the subclavian groove behind the scalene tubercle. The neck of the first rib is crossed by the sympathetic trunk, superior intercostal artery, and T1 of the brachial plexus. The first digitation of the serratus anterior muscle attaches to the outer edge, and the suprapleural membrane (Sibson’s fascia) is attached to the inner border.

Question 7

What are the characteristics of the second rib?

Answer 7

The second rib is less curved than the first rib and is twice as long.

Question 8

What are the characteristics of the tenth rib?

Answer 8

The tenth rib has only one articular facet on its head.

Question 9

What are the characteristics of the eleventh and twelfth ribs?

Answer 9

The eleventh and twelfth ribs are short, have no tubercles, and only have a single facet on their heads. The eleventh rib has a shallow subcostal groove, while the twelfth rib has no subcostal groove and no angle.

Question 10

What can happen as a result of rib fractures?

Answer 10

Fracture of any rib may lead to trauma to the lung and the development of a pneumothorax (collapsed lung).

Question 11

Which organs can be affected by fractures of the lower ribs?

Answer 11

Fracture of the left lower ribs (ninth, tenth, and eleventh) may traumatize the spleen, while fracture of the right lower ribs may traumatize the right lobe of the liver.

Question 12

What other complications can occur due to rib fractures?

Answer 12

Rib fractures may also cause trauma to related intercostal vessels, leading to the accumulation of blood in the chest cavity (haemothorax).

Question 13

What happens in coarctation of the aorta?

Answer 13

In coarctation of the aorta, collateral vessels develop between the vessels above and below the blockage

Question 14

How does the blood supply to the intercostal arteries bypass the narrowed aorta?

Answer 14

The superior intercostal artery, which is derived from the costocervical trunk of the subclavian artery, supplies blood to the intercostal arteries of the aorta, bypassing the narrowed segment.

Question 15

What changes occur in the intercostal vessels due to increased flow in coarctation of the aorta?

Answer 15

As a consequence of increased blood flow, the intercostal vessels dilate and become more tortuous.

Question 16

What can be seen on an X-ray in cases of coarctation of the aorta?

Answer 16

On an X-ray, notching can be observed on the lower border of the ribs. This notching is caused by the erosion of the ribs due to the dilated and tortuous intercostal vessels.

Question 17

What is the incidence of cervical ribs?
How often are cervical ribs bilateral?

Answer 17

The incidence of cervical ribs is 1 in 200 individuals.
Cervical ribs are bilateral in approximately 1 in 500 individuals.

Question 18

What are the possible variations in the structure of cervical ribs?

Answer 18

A cervical rib may be complete, articulating with the transverse process of the seventh cervical vertebra behind and the first rib in front. However, it can also have a free distal extremity or be represented only by a fibrous band.

Question 19

What symptoms can cervical ribs cause?

Answer 19

Cervical ribs may cause vascular or neurological symptoms.

Question 20

What are the vascular consequences of cervical ribs?

Answer 20

Vascular consequences of cervical ribs include poststenotic dilatation of the subclavian artery, which can lead to local turbulence, thrombosis, and the possibility of distal emboli. Subclavian aneurysm may also arise.

Question 21

What neurological symptoms can result from pressure on the lower trunk of the brachial plexus by cervical ribs?

Answer 21

Pressure on the lower trunk of the brachial plexus can result in paraesthesia (abnormal sensation) in the dermatomal distribution of C8/T1, along with wasting (muscle atrophy) of the small muscles of the hands (myotome T1).

Question 22

What are the three parts of the sternum?

Answer 22

The sternum consists of the manubrium, body, and xiphoid.

Question 23

What are the characteristics of the manubrium?

Answer 23

The manubrium is approximately triangular in shape and articulates with the medial end of the clavicle. The first costal cartilage and upper part of the second also articulate with the manubrium. It articulates with the body of the sternum at the manubriosternal joint (angle of Louis).

Question 24

What are the relations of the manubrium?

Answer 24

The manubrium serves as the anterior boundary of the superior mediastinum. Its lowest part is related to the arch of the aorta. The upper part is related to the left brachiocephalic vein, left brachiocephalic artery, left common carotid artery, and left subclavian artery. Laterally, it is related to the lungs and pleura.

Question 25

What are the characteristics of the body of the sternum?

Answer 25

The body of the sternum is composed of four pieces called sternebrae. Its lateral margins are notched to receive most of the second and third to seventh costal cartilages.

Question 26

What are the relations of the body of the sternum?

Answer 26

On the right side of the median plane, the body is related to the right pleura and the thin anterior border of the right lung, which intervenes between it and the pericardium. On the left side of the median plane, the upper two pieces are related to the pleura and left lung, while the lower two pieces are related directly to the pericardium.

Question 27

What are the characteristics of the xiphoid?

Answer 27

The xiphoid is small and cartilaginous, remaining so into adult life. It may become more prominent if the patient loses weight.

Question 28

What is the function of the external intercostal muscle?

Answer 28

The external intercostal muscle passes downwards and forwards from the rib above to the rib below. In the front, it is replaced by the anterior intercostal membrane.

Question 29

What is the function of the internal intercostal muscle?

Answer 29

The internal intercostal muscle passes downwards and backwards. It is deficient behind where it is replaced by the posterior intercostal membrane.

Question 30

What is the function of the innermost intercostal muscle?

Answer 30

The innermost intercostal muscle may cover more than one intercostal space.

Question 31

Where does the neurovascular bundle lie within the intercostal space?

Answer 31

The neurovascular bundle lies between the internal and the innermost intercostal muscles.

Question 32

What does the neurovascular bundle consist of?

Answer 32

The neurovascular bundle consists of the vein, artery, and nerve. The vein lies directly in the groove on the undersurface of the corresponding rib.

Question 33

Where does the trachea extend from and to?

Answer 33

The trachea extends from the lower border of the cricoid cartilage (level of the sixth cervical vertebra) to the termination into two main bronchi (level of the fifth thoracic vertebra). It is approximately 11 cm long.

Question 34

What is the composition of the trachea and how is it prevented from collapsing?

Answer 34

The trachea is composed of fibroelastic tissue and is prevented from collapsing by a series of U-shaped cartilaginous rings. These rings are open posteriorly, and the ends are connected by smooth muscle called trachealis.

Question 35

What is the lining of the trachea composed of?

Answer 35

The lining of the trachea is composed of columnar ciliated epithelium that contains numerous goblet cells.

Question 36

What are the anterior, lateral, and posterior relations of the trachea in the neck?

Answer 36

In the neck, the trachea is anteriorly related to the isthmus of the thyroid gland over the second to fourth tracheal rings, inferior thyroid veins, sternohyoid, and sternothyroid muscles. Laterally, it is related to the lobes of the thyroid gland and the carotid sheath. Posteriorly, it is related to the esophagus and the recurrent laryngeal nerves in the groove between the trachea and esophagus.

Question 37

What are the anterior and posterior relations of the trachea in the thorax?

Answer 37

In the thorax, the trachea is anteriorly related to the brachiocephalic artery, left common carotid artery, left brachiocephalic vein, and thymus. Posteriorly, it is related to the esophagus and the recurrent laryngeal nerves. On the right side, it is related to the vagus nerve, azygos vein, and pleura. On the left side, it is related to the aortic arch, left common carotid artery, left subclavian vein, left recurrent laryngeal nerve, and pleura.

Question 38

What is the level at which the trachea terminates and divides into right and left bronchi?

Answer 38

The trachea terminates at the level of the sternal angle, dividing into right and left bronchi.

Question 39

What are the characteristics of the right main bronchus?

Answer 39

The right main bronchus is wider, shorter, and more vertical than the left main bronchus. It is approximately 2.5 cm long and passes downwards and laterally behind the ascending aorta and superior vena cava (SVC) to enter the hilum of the lung.

Question 40

What are the anatomical relationships of the right main bronchus?

Answer 40

The azygos vein arches over the right main bronchus from behind to enter the SVC. The pulmonary artery lies first below and then anterior to it. It gives off the upper lobe bronchus before entering the lung and divides into bronchi to the middle and inferior lobes within the lung.

Question 41

What are the characteristics of the left main bronchus?

Answer 41

The left main bronchus is approximately 5 cm long and passes downwards and laterally below the arch of the aorta, in front of the esophagus and descending aorta. It gives off no branches until it enters the hilum of the lung, where it divides into bronchi to the upper and lower lobes. The pulmonary artery lies at first anterior to, and then above, the bronchus.

Question 42

What are the clinical points related to the trachea and bronchi?

Answer 42

The trachea can be displaced or compressed by adjacent structures such as the thyroid or arch of the aorta. It may also be displaced if the mediastinum is pushed across, for example, by tension pneumothorax. Calcification of tracheal rings may occur in the elderly and can be visible on X-ray. Foreign bodies are more likely to be aspirated into the right main bronchus due to its wider and more vertical nature. Distortion and widening of the carina, seen at bronchoscopy, usually indicate enlargement of the tracheobronchial lymph nodes at the bifurcation by carcinoma.

Question 43

What are the possible types of skin incisions for tracheostomy?

Answer 43

Either a vertical or cosmetic transverse skin incision may be employed.

Question 44

How is a vertical incision for tracheostomy made?

Answer 44

A vertical incision is made downwards from the cricoid cartilage, passing between the anterior jugular veins.

Question 45

Where is a transverse cosmetic skin crease incision made for tracheostomy?

Answer 45

A transverse cosmetic skin crease incision is placed halfway between the cricoid cartilage and suprasternal notch.

Question 46

What structures are encountered during the tracheostomy procedure?

Answer 46

After making the incision and splitting the pretracheal fascia, bleeding may occur from anterior relations such as the anastomosis between anterior jugular veins, inferior thyroid veins, and thyroidea ima artery (when present). In young children, the brachiocephalic artery, left brachiocephalic vein, and thymus may be apparent in the lower part of the wound.

Question 47

What is encountered after splitting the pretracheal fascia and retracting the strap muscles in tracheostomy?

Answer 47

The isthmus of the thyroid is encountered and can be retracted upwards or divided between clamps to expose the cartilages of the trachea.

Question 48

What is the shape of the lungs?

Answer 48

Conical

Question 49

Where is the apex of each lung located?

Answer 49

The apex of each lung extends above the sternal end of the first rib.

Question 50

What is the base of each lung related to?

Answer 50

The base of each lung is concave and related to the diaphragm.

Question 51

What is the mediastinal surface of each lung related to?

Answer 51

The mediastinal surface of each lung is concave and related to the pericardium.

Question 52

What is the shape of the posterior border of each lung?

Answer 52

The posterior border of each lung is rounded and occupies the groove by the side of the vertebrae.

Question 53

How many lobes does the right lung have?

Answer 53

The right lung has three lobes—upper, middle, and lower—divided by the oblique and horizontal fissures.

Question 54

How many lobes does the left lung have?

Answer 54

The left lung has two lobes and only an oblique fissure.

Question 55

What is the equivalent of the middle lobe of the right lung in the left lung?

Answer 55

The lingula, which lies between the cardiac notch and oblique fissure, is the equivalent of the middle lobe of the right lung in the left lung

Question 56

What is the notch in the anterior border of the left lung?

Answer 56

The anterior border of the left lung has a notch produced by the heart called the cardiac notch.