Thoracic Blood/Nerve Supply

Anterior rami of T1-T11

Anterior rami of T1-T11

These nervous structures form the intercostal nerves
- Bonus: "" T12 forms the subcostal nerve

Posterior rami of T1-T12

These nervous structures pass posteriorly to supply the joints, muscles, and skin of the back in the thoracic region

Between the pleura

In the posterior thorax, the intercostal nerve lies here instead of between the intercostalis intimi and internal intercostal muscle
- Top to bottom: VAN

myotome

Group of muscles innervated by a single spinal nerve

dermatome

Area of skin supplied by a single spinal nerve
- T4 includes the nipple
- T10 includes the umbilicus

First intercostal nerve (T1)

This spinal nerve joints the ventral ramus of C8 to form the lower trunk of the brachial plexus

Second intercostal nerve (T2)

This spinal nerve gives a branch that joins the medial cutaneous nerve of arm, called intercostobrachial nerve

- In CAD, pain is referred along this nerve to the medial arm

mediastinitis

Due to:

- Deep infection of the neck

- Penetrating chest wound

- Esophageal perforation

Air can escape to CT spaces and produce subcutaneous emphysema (air bubbles below the skin)

mediastinoscopy

Diagnostic procedure to obtain tracheobronchial lymph specimens

- Small incision above suprasternal notch

- Superior mediastinum is explored

- Tuberculosis, sarcoidosis, lymphoma, lung cancer

mediastinal lymph nodes

Lung cancer typically involves these.

Enlargement can compress:

- left recurrent laryngeal nerve (hoarseness)

- Superior vena cava (congestion of veins of upper body)

- Sympathetic trunk, phrenic nerves, trachea, bronchi, esophagus

thymus

This organ is supplied as follows:

- Artery: Inferior thyroid, internal thoracic, mediastinal arteries

- Nerve: Small branches of the vagus, recurrent laryngeal, phrenic

- Venous: Drains into left brachiocephalic and internal thoracic veins

DiGeorge Syndrome

Most common cause of thymic aplasia - thymus fails to develop > T cells do not mature - non-functional
- Immunodeficiency

thymic hyperplasia

Idiopathic inflammation of the thymus often associated with steroids, rebound to chemotherapy, radiation, burns, or other systemic stress

- Lymphoid hyperplasia

thymoma

Tumor of the thymus, found in 10-15% of patients with myasthenia gravis (progressive muscular weakness at NMJ)

- Compression of the recurrent laryngeal nerve

- Treatment by complete thymectomy

3rd/4th ICS

Where should the sternotomy be carried in a thymectomy procedure?
- For patients with myasthenia gravis and thymoma

Cervical esophagus (upper)

Artery: Inferior thyroid artery

Vein: Inferior thyroid vein

Lymph: Deep Cervical nodes

- This structure has skeletal muscle

Thoracic esophagus (middle)

Artery: Esophageal branches of the aorta and bronchial arteries

Vein: Azygos and hemiazygos vein

Lymph: Posterior mediastinal nodes

- This structure has a mix of skeletal and smooth muscle

Abdominal esophagus (lower)

Artery: Esophageal branches of left gastric and left inferior phrenic arteries

Vein: Hemiazygos vein, tributary of interior vena cava + left gastric vein, tributary of portal vein

Lymph: Left gastric nodes

- This structure has only smooth muscle

Recurrent laryngeal and esophageal plexus (vagus nerves)

The parasympathetic nerve supply to the esophagus is supplied by these nerves

- 1st supplies the upper half, 2nd supplies the lower half

- These nerves are sensory, motor, and secretomotor in function

Middle cervical and upper 4 thoracic ganglia

These ganglia supply the sympathetic innervation for the esophagus.

- 1st supplies the upper half, 2nd supplies the lower half as the esophageal plexus

- These nerves are sensory and vasomotor in function

Portal hypertension

What condition leads to esophageal varices?

- The lower esophagus is drained by these - dilation of esophageal veins > rupture

- On barium swallow - worm-like shadows

Left atrial enlargement, aortic arch aneurysm, lymph node enlargement, abnormal right subclavian artery

What 4 conditions leads to dysphagia due to compression of the esophagus from the outside?

Barrett's esophagus

Lower esophageal squamous epithelium > gastric columnar epithelium with goblet cells due to chronic acid exposure

- Typically due to malfunction in LES

- Associated with esophageal adenocarcinoma

Lower 1/3

Malignant tumors of the esophagus typically affect this portion
- This drains to the celiac lymph nodes past the diaphragm, spreading to these nodes

Esophagojejunostomy

If there is a tumor of the esophagus, often the esophagus, stomach, spleen, and omenta will all need to be resected due to the communication with celiac lymph nodes.

How is the continuity of the gut restored?

Trachea

This structure is supplied by:
- Artery: Inferior thyroid arteries
- Vein: Left brachiocephalic vein
- Lymph: Pretracheal and paratracheal nodes

Vagus and recurrent laryngeal

These nerves supply parasympathetic innervation to the trachea

- Sensory, secretomotor (to the mucus membrane), and motor (to the trachealis) in function

Middle cervical ganglion

This ganglion supplies sympathetic innervation to the trachea

- Travels along thyroid arteries

- Vasomotor

Mediastinal shift

The trachea is normally midline in position, any shift of the trachea indicates a _

- Palpated in the suprasternal notch

Thyroid, thymus, lymph nodes, aortic arch

The trachea may be compressed by enlargement of these 4 structures, leading to dyspnea, cough, and hoarseness

Between 2nd/3rd tracheal rings

Where is a tracheostomy typically done?
- In the case of blockage in nose/larynx