Thoracic anatomy notes

Question 1

Superior Mediatinum borders

Answer 1

Superior – Thoracic inlet.
Inferior – Continuous with the inferior mediastinum at the level of the sternal angle.
Anterior – Manubrium of the sternum.
Posterior – Vertebral bodies of T1-4.
Lateral – Pleurae of the lungs.

Question 2

Three major branches of the aortic arch arise within the superior mediastinum?

Answer 2

Brachiocephalic artery
Left Common carotid artery
Left Subclavian artery

Question 3

Right vagus nerve path

Answer 3

runs parallel to the trachea and passes posteriorly to the superior vena cava and the right primary bronchus.

Question 4

Left vagus nerve path

Answer 4

enters the superior mediastinum between the left common carotid and the left subclavian arteries.
It descends anteriorly to the aortic arch, before travelling posterior to the left bronchus.

Question 5

left recurrent laryngeal nerve path

Answer 5

arises from the left vagus nerve as it passes the aortic arch. It loops under the arch, to the left of ligamentum arteriosum, before continuing its journey to the larynx in the tracheal-oesophageal groove.

Question 6

Phrenic Nerve Path

Answer 6

From the anterior surface of the anterior scalene muscle, the phrenic nerves (roots C3, C4 and C5) enter the superior mediastinum lateral to the great vessels.

Question 7

Where do Ribs 1-7 attach

Answer 7

Independently to sternum

Question 8

Where do Ribs 8-10 attach

Answer 8

Ribs 8 – 10 attach to the costal cartilages superior to them.

Question 9

Where do Ribs 11 and 12 attach?

Answer 9

Ribs 11 and 12 do not have an anterior attachment and end in the abdominal musculature. Because of this, they are sometimes called ‘floating ribs’.

Question 10

Azygos vein – Formed by?

Answer 10

union of the right lumbar vein and the right subcostal vein. It enters the mediastinum via the aortic hiatus and drains into the superior vena cava.

Question 11

Hemiazygos vein - Formed by?

Answer 11

union of the left lumbar vein and left subcostal vein. It enters the mediastinum through the left crus of the diaphragm, ascending on the left side. At the level of T8, it turns to the right and combines with the azygos vein.

Question 12

Accessory hemiazygos vein

Answer 12

Formed by the union of the fourth to eighth intercostal veins. It drains into the azygos vein at T7.

Question 13

Ligaments of vertebral column

Anterior and posterior longitudinal ligaments:

Answer 13

Long ligaments that run the length of the vertebral column, covering the vertebral bodies and intervertebral discs.

Question 14

Ligamentum flavum

Answer 14

Connects the laminae of adjacent vertebrae.

Question 15

Interspinous ligament

Answer 15

Connects the spinous processes of adjacent vertebrae.

Question 16

Supraspinous ligament:

Answer 16

Supraspinous ligament: Connects the tips of adjacent spinous processes.

Question 17

11 pairs of external intercostal muscles. What are their origins and attachements?

Answer 17

Originate at the lower border of the rib, inserting into the superior border of the rib below

Question 18

Actions and innervation of external intercostal muscles?

Answer 18

Elevates ribs, increases thoracic volume

Innervation - Intercostal nerves T1-t11

Question 19

Internal intercostals - deep to the external intercostals. Like the external intercostals, they run from the rib above to the one below, but in an opposite direction (inferoposteriorly)

Answer 19

Attachments: Originates from the lateral edge of the costal groove and inserts into the superior surface of the rib below.
Actions: The interosseous part reduces the thoracic volume by depressing the ribcage, and the interchondral part elevates the ribs.
Innervation: Intercostal nerves (T1-T11).

Question 20

Transversus Thoracis

Answer 20

continuous with transversus abdominis inferiorly.

Attachments: From the posterior surface of the inferior sternum to the internal surface of costal cartilages 2-6.
Actions: Weakly depress the ribs.
Innervation: Intercostal nerves (T2-T6).

Question 21

Right crus

Answer 21

Arises from L1-L3 and their intervertebral discs. Some fibres from the right crus surround the oesophageal opening, acting as a physiological sphincter to prevent reflux of gastric contents into the oesophagus.

Question 22

Left crus

Answer 22

Arises from L1-L2 and their intervertebral discs.

Question 23

Three openings and structures passing through diaphragm

Answer 23

T8 - Inferior vena cava
T10- Oesophagus, Vagus x2, Oesophageal branches of left gastric artery.vein
T12- Aorta, Thoracic duct, Azygous vein

Question 24

Blood supply to the diaphragm?

Answer 24

Inferior phrenic arteries - directly from the AA

Question 25

What will bilateral diaphragmatic paralysis show on LFTs

Answer 25

Restrictive deficit

Pardoxical movements of diaphragm - down on expiration, up on inspiration

Question 26

What pharyngeal pouch is thymus gland derived from?

Answer 26

Third pharyngeal pouch

Question 27

Relevance of DiGeorge syndrome to thymus?

Answer 27

DiGeorge- CATCH

C ONGENITAL HEART SOUNDS
A BNORMAL FASCIES
T HYMIC APLASIA
C LEFT PALATE
H YPOPARATHYROIDISM 

Susceptible to recurrent infections due to underdeveloped immune system

Question 28

Blood supply to medial aspect of the breast?

Answer 28

Internal Mammary artery (aka internal thoracic) - branche of subcalvian

Question 29

Blood supply to the lateral aspect of the breast?

Answer 29

1) Lateral thoracic and thoracoacromial branches – originate from the axillary artery.
2) Lateral mammary branches – originate from the posterior intercostal arteries (derived from the aorta). They supply the lateral aspect of the breast in the 2nd 3rd and 4th intercostal spaces.
3) Mammary branch – originates from the anterior intercostal artery.

Question 30

Breast location in thoracic wall?

Answer 30

anterior thoracic wall.
extends horizontally from the lateral border of the sternum to the mid-axillary line.
2nd and 6th costal cartilages vertically

Question 31

Lymphatic drainage of the breast

Answer 31

Axillary nodes (75%)
Parasternal nodes (20%)
Posterior intercostal nodes (5%)

Question 32

Lymphatic drainage of the Skin overlying breast

Answer 32

Axillary, inferior deep cervical, inferiorclavicular nodes

Question 33

Lymphatic drainage of nipple and areola

Answer 33

Drains to subareolar lymphatic plexus

Question 34

Nerve supply to the breast

Answer 34

anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves.