Trachea

- 10 cm long- Begins at lower border of cricoid cartilage opposite 6th cervical vertebra- Ends at lower border of 4th thoracic vertebra where it divides into right and left principal bronchi

just to the right median plane- Descends exactly in median plane, its upper

Trachea and major bronchi of lungs

Relations of trachea

Anteriorly, posteriorly, on each side

Relations in the chest

- Superior mediastinum- Anterior : manubrium sterni, remains of thymus gkand, left brachiocephalic vein, arch of aorta- Posterior : esophagus, left recurrent laryngeal nerve- Right side : right vague nerve

Right principal bronchus

Course and relations

- Passes to right behind right pulmonary artery, having only one bronchial artery on its posterior surface

- The azygos vein arches above its origin to enter SVC- Differs from left bronchus in being wider and shorter, more in line with trachea

Divisions

- Divides before reaching hilus of right lunginto right superior lobar bronchus and right inferior lobar bronchus

Left principal bronchus

Oesophagus

- 25 cm long- Double the length of trachea- Begins at level or cricoid cartilage as continuation of lower end of pharynx- Descends in median plane in front of vertebral column then deviates to left at level of 7th

thoracic vertebra where it crosses in front of desdending aorta - Enters abdomen by piercing the right crus of diaphragm, opposite 10th thoracic vertebra then

rapidly ends at cardiac orifice of stomach at level of 11th thoracic vertebra

Relations in neck

Anteriorly : trachea, recurrent laryngeal nerve

Posterior : vertebral column

Each side : common carotid artery,lobe of thyroid gland

Relations in chest

Anteriorly, posteriorly : right post intercstal arteries, thoracic duct, azygis vein, terminal oarts of 2 hemiazgous vein, descending aorta, , left subclavian artery

Esophageal arteries arises from

- Inferior thyroid artery to cervical part- Descending thoracic aorta to thoracic part- Left gastric artery to abdominal part- Inferior phrenic artery to abdominal part

Venous drainage

- Cervical part : to inferior thyroid veins, to left brachioceg=halic veins- Thoracic part : to azygous vein then to SVC- Abdominal prt :

Vagus nerve

course and relations

- Descends downwards and backwards onside of trachea- Passes behind root of lungm=, where it breaks up into several branches that join symohatetic

branches from 2nd, 3rd and 4th ganglion to form posterior pulmonary plexus and sends twigs to anterior pulmonary plexus

- From posterior pulmonary plexus 2-3 branches descends around esophagus to form esophageal plexus from both vagi

- From lower end of esophageal plexus form anterior vagal trunk and posterior vagal trunk descend on corresponding surfaces of abdominal part of esophagus

Phrenic nerve

Course and relation

- Formed in neck from anterior primary rami of 3th, 4th and 5th cranial nerve, mainly 4th

- Descends on anterior surface of scalenus anterior muscle crossing muscle from lateral to medial deep to sternomastoid muscle

- Carry motor and sensory fibers

- Motor : diapraghm- Sensory : pericardium and parital pleura

Relations of right phrenic nerve

- Descends in right side of right brachiocephalic vein, SVC and IVC, pericardium covering right atrium

- Passes through opening of IVC in diapraghm to supply abdominal surface in right side- It is accompanied by right pericardiaco-phrenic artery

Relations of left phrenic nerve

- Descends on left side of left subclavian and left common carotid arteries- Arch of aorta- Left ventricle separated by pericardium- Pierces substance of diapraghm to supply it from its abdominal surface in left side- Accompanied by left paricardiaco-phrenic artery- Covered laterally by left pleura nad lung

Appliedanatomy

- Irritation of diapraghm referredpain is felt at cutaneous areas supplied by same spinal segments of phrenic nerve

- Found at tip of shoulder

Thoracic duct