Posterior mediastinum - descending (thoracic) aorta and oesophagus (dave's notes)

Question 1

Where does the thoracic aorta commence?

Answer 1

T4, just to the left of the midline. Slanting until it sits in the midline.

Question 2

Where does the oesophagus commence and terminate? How long is it?

Answer 2

25cm, commences at cricopharyngeus (cricoid cartilage) at C6 in the midline, running to the cardiac orifice at T10, 1” to the left of the midline.

Question 3

What does the descending thoracic aorta give off?

Answer 3

9 posterior intercostal arteries, the subcostal artery, bronchial arteries and small oesophageal vessels.

Question 4

What are the posterior relations of the oesophagus?

Answer 4

Initially in contact with the vertebral bodies, the oesophagus inclines forward so that it is in front of the thoracic aorta

Question 5

How long is the intraabdominal part of the oesophagus?

Answer 5

1-2cm

Question 6

What vessels are on the left and right of the oesophagus?

Answer 6

Crossed by the arch of the aorta on its left side, azygous on its right

Question 7

What are the relations of the oesophagus relative to the pulmonary roots?

Answer 7

Below the tracheal bifurcation, the oesophagus is crossed by the left main bronchus and the right pulmonary artery

Question 8

What is the general course of the oesophagus from the thoracic inlet?

Answer 8

From the thoracic inlet it inclines from the right to the left, posteriorly.

Question 9

What is notable about oesophageal attachments just above the diaphragm?

Answer 9

Firm connective tissue with the aorta here.

Question 10

What is the narrowest part of the oesophagus?

Answer 10

The cricopharyngeal sphincter (15cm from incisor teeth)

Question 11

List the constrictions of the oesophagus

Answer 11

The cricopharungeal sphincter
Slight constrictions:
-where it is crossed by the aortic arch (22cm from incisor teeth)
-crossed by the left main bronchus (27cm from incisor teeth)
-on passing into the diaphragm (38cm from incisor teeth)
If the left atrium is enlarged it can cause an indentation.

Question 12

What is the blood supply and drainage of the upper 1/3rd of oesophagus?

Answer 12

Upper 1/3rd from the inferior thyroid artery, venous drainage to the inferior thyroid veins

Question 13

What is the blood supply and drainage of the middle third of the oesophagus?

Answer 13

Middle third form the oesophageal branches of the aorta, venous to the azygous

Question 14

What is the blood supply and drainage of the lower third of the oesophagus?

Answer 14

The left gastric artery, venous drainage to the left gastric vein.

Question 15

Describe the lymphatic drainage of the oesophagus

Answer 15

Follows the arteries:
Upper third to deep cervical
Middle third to tracheobronchial group
Lower third to preaortic nodes.

Question 16

Describe the structure of the oesophagus

Answer 16

Inner circular and outer longitudinal layers muscle; skeletal (for rapid contraction) to the upper third, visceral in the lower third.

Question 17

What is the inner circular layer of oesophageal muscle in continuity with?

Answer 17

The cricopharyngeus muscle

Question 18

What contributes as a physiological sphincter?

Answer 18

The lower 5cm of inner circular muscle (although no anatomical demarcation of this.