Thorax Anatomy 2

Question 1

What does the thoracic wall consist of?

Answer 1

skeletal elements and muscles

Question 2

What does the thoracic wall consist of posteriorly?

Answer 2

made up of twelve thoracic vertebrae and their intervening intervertebral discs

Question 3

What does the thoracic wall consist of laterally?

Answer 3

-the wall is formed by ribs (twelve on each side) -three layers of flat muscles, which span the intercostal spaces between adjacent ribs, move the ribs, and provide support for the intercostal spaces;

Question 4

What does the thoracic wall consist of anteriorly?

Answer 4

The wall is made up of the sternum

Question 5

What does the sternum consist of?

Answer 5

-manubrium of sternum -body of sternum -xiphoid process

Question 6

What forms the sternal angle?

Answer 6

-The manubrium of sternum, angled posteriorly on the body of sternum at the manubriosternal joint -This is a major surface landmark used by clinicians in performing physical examinations of the thorax

Question 7

What is the vital end of each rib composed of?

Answer 7

costal cartilage, which contributes to the mobility and elasticity of the wall.

Question 8

What do ribs articulate with?

Answer 8

1. All ribs articulate with thoracic vertebrae posteriorly 2. Most ribs (from rib II to IX) have three articulations with the vertebral column 3. The head of each rib articulates with the body of its own vertebra and with the body of the vertebra above 4. As these ribs curve posteriorly, each also articulates with the transverse process of its vertebra. 5. Anteriorly, the costal cartilages of ribs I to VII articulate with the sternum.

Question 9

What do the costal cartilages VIII to X articulate with?

Answer 9

the inferior margins of the costal cartilages above them

Question 10

What are ribs XI and XII called?

Answer 10

-floating ribs -they do not articulate with other ribs, costal cartilages, or the sternum -Their costal cartilages are small, only covering their tips.

Question 11

What does the thoracic wall extend between?

Answer 11

-the superior thoracic aperture, bordered by vertebra TI, rib I, and the manubrium of the sternum 
-the inferior thoracic aperture, bordered by vertebra TXII, rib XII, the end of rib XI, the costal margin, and the xiphoid process of the sternum

Question 12

Where do intercostal spaces lie between?

Answer 12

adjacent ribs and are filled by intercostal muscles

Question 13

Where are intercostal nerves?

Answer 13

Intercostal nerves and associated major arteries and veins lie in the costal groove along the inferior margin of the superior rib and pass in the plane between the inner two layers of muscles

Question 14

What happens in each space?

Answer 14

1. The vein is the most superior structure and is therefore highest in the costal groove 2. The artery is inferior to the vein, and the nerve is inferior to the artery and often not protected by the groove. 3. Therefore, the nerve is the structure most at risk when objects perforate the upper aspect of an intercostal space 4. Small collateral branches of the major intercostal nerves and vessels are often present superior to the inferior rib below.

Question 15

What is deep to the intercostal spaces and ribs (and separating these structures from the underlying pleura) ?

Answer 15

a layer of loose connective tissue, called endothoracic fascia, which contains variable amounts of fat

Question 16

What is superficial to the spaces?

Answer 16

-deep fascia, superficial fascia, and skin -muscles associated with the upper limbs and back overlie the spaces.

Question 17

What is a cervical rib?

Answer 17

-Cervical ribs are present in approximately 1% of the population. -A cervical rib is an accessory rib articulating with vertebra CVII; the anterior end attaches to the superior border of the anterior aspect of rib I. -Plain radiographs may demonstrate cervical ribs as small horn-like structures -It is often not appreciated by clinicians that a fibrous band commonly extends from the anterior tip of the small cervical ribs to rib I, producing a “cervical band” that is not visualized on radiography. In patients with cervical ribs and cervical bands, structures that normally pass over rib I are elevated by, and pass over, the cervical rib and band.

Question 18

What is thoracic outlet syndrome?

Answer 18

-Clinically, “thoracic outlet syndrome” is used to describe symptoms resulting from abnormal compression of the brachial plexus of nerves as it passes over the first rib and through the axillary inlet into the upper limb -The anterior ramus of T1 passes superiorly out of the superior thoracic aperture to join and become part of the brachial plexus -The cervical band from a cervical rib is one cause of thoracic outlet syndrome by putting upward stresses on the lower parts of the brachial plexus as they pass over the cervical band and related cervical rib.

Question 19

What happens in the subcutaneous position of the sternum?

Answer 19

-The subcutaneous position of the sternum makes it possible to place a needle through the hard outer cortex into the internal (or medullary) cavity containing bone marrow -Once the needle is in this position, bone marrow can be aspirated -Evaluation of this material under the microscope helps clinicians diagnose certain blood diseases such as leukemia

Question 20

What can happen after severe trauma?

Answer 20

-Single rib fractures are of little consequence, though extremely painful. -After severe trauma, ribs may be broken in two or more places. If enough ribs are broken, a loose segment of chest wall, a flail segment ( flail chest ), is produced -When the patient takes a deep inspiration, the flail segment moves in the opposite direction to the chest wall, preventing full lung expansion and creating a paradoxically moving segment. -If a large enough segment of chest wall is affected, ventilation may be impaired and assisted ventilation may be required until the ribs have healed.

Question 21

What is the diaphragm?

Answer 21

a thin musculotendinous structure that fills the inferior thoracic aperture and separates the thoracic cavity from the abdominal cavity

Question 22

What is the diaphragm attach peripherally to?

Answer 22

1. xiphoid process of the sternum, 
2. cstal margin of the thoracic wall, 3. ends of ribs XI and XII, 4.ligaments that span across structures of the posterior abdominal wall, and 
5. vertebrae of the lumbar region.

Question 23

What happens from the peripheral attachments of the diaphragm?

Answer 23

-muscle fibers converge to join the central tendon -the pericardium is attached to the middle part of the central tendon.

Question 24

What is in the median sagittal plane ?

Answer 24

-the diaphragm slopes inferiorly from its anterior attachment to the xiphoid, approximately at vertebral level TVIII/IX, to its posterior attachment to the median arcuate ligament , crossing anteriorly to the aorta at approximately vertebral level TXII

Question 25

What are some structures that travel between the throat and abdomen passing through the diagram or between the diaphragm and its peripheral attachments?

Answer 25

1. The inferior vena cava passes through the central tendon at approximately vertebral level TVIII. 2. The esophagus passes through the muscular part of the diaphragm, just to the left of midline, approximately at vertebral level TX. 3. The vagus nerves pass through the diaphragm with the esophagus. 4. The aorta passes behind the posterior attachment of the diaphragm at vertebral level TXII. 
5. The thoracic duct passes behind the diaphragm with the aorta. 
6. The azygos and hemiazygos veins may also pass through the aortic hiatus or through the crura of the diaphragm. -Other structures outside the posterior attachments of the diaphragm lateral to the aortic hiatus include the sympathetic trunks. The greater, lesser, and least splanchnic nerves penetrate the crura.

Question 26

Where are the pleural cavities?

Answer 26

Two pleural cavities , one on either side of the mediastinum, surround the lungs

• Superiorly, they extend above rib I into the root of the neck.
• Inferiorly, they extend to a level just above the costal margin.
• The medial wall of each pleural cavity is the mediastinum.

Question 27

Where are the lungs?

Answer 27

-lie on either side of the mediastinum surrounded by the right and left pleural cavities -Air enters and leaves the lungs via main bronchi, which are branches of the trachea.

Question 28

Which lung is bigger?

Answer 28

The right lung is normally a little larger than the left lung because the middle mediastinum, containing the heart, bulges more to the left than to the right.

Question 29

What is the structure of the lung?

Answer 29

-Each lung has a half-cone shape, with a base, apex, two surfaces, and three borders 
-The base sits on the diaphragm. 
-The apex projects above rib I and into the root of the neck.

Question 30

What are the two surfaces of the lung? Where are they?

Answer 30

1. The costal surface lies immediately adjacent to the ribs and intercostal spaces of the thoracic wall 2. The mediastinal surface lies against the mediastinum anteriorly and the vertebral column posteriorly and contains the comma-shaped hilum of the lung, through which structures enter and leave.

Question 31

What are the three borders of there lung? Where are they?

Answer 31

-the inferior border of the lung is sharp and separates the base from the costal surface -The anterior and posterior borders separate the costal surface from the medial surface. -Unlike the anterior and inferior borders, which are sharp, the posterior border is smooth and rounded.

Question 32

What projects inferiorly from the root of the lung?

Answer 32

1. A thin blade-like fold of pleura projects inferiorly from the root of the lung and extends from the hilum to the mediastinum 2. This structure is the pulmonary ligament 3. It may stabilize the position of the inferior lobe and may also accommodate the down-and-up translocation of structures in the root during breathing.

Question 33

Where does the vagus and phrenic nerve pass?

Answer 33

In the mediastinum, the vagus nerves pass immediately posterior to the roots of the lungs, while the phrenic nerves pass immediately anterior to them

Question 34

What is within each root and located in the hilum?

Answer 34

1. a pulmonary artery, 
2. two pulmonary veins, 
3.a main bronchus, 
4. bronchial vessels, 
5. nerves, and 6. 
lymphatics.

Question 35

What is around the hilum?

Answer 35

1. the pulmonary artery is superior at the hilum 2. the pulmonary veins are inferior 3. the bronchi are somewhat posterior in position. -On the right side, the lobar bronchus to the superior lobe branches from the main bronchus in the root, unlike on the left where it branches within the lung itself, and is superior to the pulmonary artery

Question 36

What is the thoracic wall composed of?

Answer 36

-thoracic skeleton is composed of 12 thoracic vertebrae, 12 pairs of ribs and costal cartilages and the sternum -The thoracic vertebrae are 12 in number and they are named T1 to T12.

Question 37

Describe the thoracic vertebrae

Answer 37

-Heart shaped vertebral body and they have facets on the body for articulations with the heads of the ribs. -They also have facets on the transverse process for the articulations with the tubercles of the ribs, except for ribs 11 and 12.

Question 38

What can you see in the superior view of thoracic vertebra?

Answer 38

the body, the pedicle, the transverse process, the lamina, and the spinous process.

Question 39

What does the vertebral foramen in the centre carry?

Answer 39

the spinal cord and the meningeal layers.

Question 40

What do the coastal facets do?

Answer 40

articulate with the head and tubercles of the ribs

Question 41

What are true ribs?

Answer 41

-The first seven ribs reach the sternum and are therefore called true ribs -They articulate with the sternum via their own costal cartilage.

Question 42

What are ribs 8,9,10?

Answer 42

-Ribs 8, 9, and 10 reach the sternum via the costal cartilage of the rib above and are therefore known as the false ribs.

Question 43

What are ribs 11 and 12?

Answer 43

-Ribs 11 and 12 lack an anterior attachment completely and are therefore termed floating ribs.

Question 44

Describe a rib

Answer 44

1. The head which articulates with the body of the vertebral body 2. The tubercle, which articulates with the facet on the transverse process, and we can see the costal cartilage, which attaches the rib to the sternum. -This is the external surface and this is the internal surface and the costal groove runs along the inferior surface.

Question 45

What does the first costal cartilage attach to?

Answer 45

manubrium

Question 46

What does the 2nd costal cartilages attach to?

Answer 46

joint between manibrium and the sternum (the manubriosternal joint)

Question 47

What does the 3rd to 7th costal cartilage attach to?

Answer 47

attach directly to the body of the sternum

Question 48

What does the 8th to 10th costal cartilage attach to?

Answer 48

attach to the sternum via the costal cartilages of the rib above

Question 49

What does the 11th and 12th costal cartilage attach to?

Answer 49

they have no anterior attachment at all to the sternum (floating ribs).

Question 50

What is the superior thoracic aperture?

Answer 50

-It is a ring formed from the first thoracic vertebra posterior, the first ribs, and the manubrium. -This is a conduit for structures passing from the head and neck down into the thorax and into the abdominal cavity, structure such as the esophagus and the trachea. -It is also a conduit for vessels which are going to and from the heart. We can see the internal jugular vein here and subclavian veins here. -Posterior to those, we can see subclavian arteries and also the common carotid arteries. Note on this slide that the apex of the right lung, note how high the apex of the right lung projects into the root of the neck.

Question 51

What does the diaphragm have?

Answer 51

-The diaphragm has a flat, central tendon with muscle radiating out to the costal margin and the vertebrae 1. The dome flattens to increase the vertical diameter of the chest 2. It pulls the costal margin up to increase both the transverse and anteroposterior diameters.

Question 52

What do the intercostal muscles do?

Answer 52

-The intercostal muscles seen here, which sit in between adjacent ribs, help to stiffen the chest wall to improve the efficiency of the breathing movements.

Question 53

What do the sternum and ribs do in the movement of the chest?

Answer 53

-The sternum and ribs move to increase the chest volume and can be likened to a pump handle as seen towards the top of this slide where the sternum moves anteriorly and superiorly to increase the anteroposterior dimension of the chest, and the ribs move in a bucket handle type movement where they elevate and increase the media-lateral dimensions of the chest.

Question 54

What do the intercostal muscles occupy?

Answer 54

-The intercostal muscles occupy the intercostal spaces, which are the spaces between the ribs. -There are three layers organized like plywood i.e at 90 degrees to each other as can be seen on the left of this slide.

Question 55

How are the external intercostals orientated?

Answer 55

-The external intercostals are orientated downwards and laterally from the lower border of the rib above to the rib below. -Muscle is replaced by a membrane at the costalchondral or rib cartilage junction as can be seen here. -Deep to the external intercostal muscles are the internal intercostals.\

Question 56

Where are the attachments?

Answer 56

-The attachments begin anteriorly at sternum from the lower border of the rib above to the rib below. -Their fibers are directed at right angles to the external intercostals. -They are replaced by membrane posteriorly.

Question 57

What is deep to the internal intercostal muscles?

Answer 57

-the innermost intercostals which are orientated in the same direction as the internal intercostals -They are relatively trivial muscles

Question 58

What is between the inter most and internal intercostals?

Answer 58

The neurvascular bundle