T, L & P 2

Question 1

Describe the role and 3 divisions of the aorta.

Answer 1

Main arterial trunk that delivers oxygenated blood from the left ventricle to the tissues of the body
Divided into;
Ascending:
Anterior to trachea
Gives rise to coronary arteries
Arch:
Moves backwards and to the left of the trachea
Gives rise to; brachiocephalic, left common carotid, left subclavian
Descending thoracic aorta:
Lies in the posterior mediastinum
Runs downwards alongside oesophagus and left lung
Passes behind the diaphragm at T12 to become abdominal aorta
Oesophagus at T10

Question 2

What is an aortic aneurysm

Answer 2

Bulging, weakened area in the wall of the aorta
Results in an abnormal widening or ballooning greater than 50% of the vessels normal diameter
Characterised by its location, shape, and cause
Once formed, an aneurysm will gradually increase in size and there will be progressive weakening of the aneurism wall
Treatment for a thoracic aneurysm may include surgical repair or removal of the aneurysm to prevent rupture

Question 3

Describe the course of the oesophagus in both cervical and thoracic regions.

Answer 3

In cervical region oesophagus behind trachea. The laryngeal pharynx continues down as the trachea anteriorly and the oesophagus posteriorly. Back of tracheas open (not covered by C-shaped cartilage ring) to allow the oesophagus to expand into when swallowing.
As oesophagus passes into the thoracic region it sits posteriorly to the trachea by fitting into the bronchus, and has a close relationship with the aorta.

Question 4

Give detail on vagus nerve

Answer 4

Arises from medulla oblongata
Autonomic control of the heart and digestive tract
Supplies motor parasympathetic fibres to all the organs except the suprarenal (adrenal) glands, from the neck down to the second segment of the transverse colon
Controls a few skeletal muscles
Superior, middle and inferior pharyngeal constrictors which help form oesophagus
Muscles of the larynx

Question 5

Give detail on laryngeal innervation

Answer 5

Innervated by the Superior Laryngeal Nerve Internal Branch and the Recurrent Laryngeal Nerve, both branches of the vagus nerve.
Sensory above the vocal folds = Superior laryngeal
Sensory below the vocal folds = Recurrent laryngeal

Question 6

Give detail on phrenic nerve

Answer 6

Originates from the cervical plexus (within head and neck)
Contains motor, sensory and sympathetic nerve fibres
Provides the only motor supply to the diaphragm (C3,4,5 keeps the diaphragm alive) as well as sensation to the central tendon.
In the thorax, each phrenic nerve supplies the mediastinal pleura and pericardium.

Enters the superior mediastinum lateral to the vagus nerve and behind the brachiocephalic veins.
Passes anteriorly to the hilum of the lung and over the pericardium of the heart, sending small pericardial branches to it

Question 7

Describe how infections can spread into the mediastinum

Answer 7

Paratracheal route to the anterior mediastinal space
Lateral pharyngeal route to the medial mediastinal space
Retropharyngealretrovisceral route to the posterior mediastinal space

(causes mediastinitis)

Question 8

Give detail on role of sympathetic chain ganglia

Answer 8

Preganglionic fibres are short and synapse with roughly 30 postganglionic neurones

This facilitates divergence and a more widespread response