Thorax Anatomy Flashcards
What are the nerve roots of the phrenic nerve and what does it supply?
Nerve roots: C3,4,5
Supplies: Diaphragm, sensation central diaphragm and pericardium
What is the path of the phrenic nerve as it enters the thorax and how does it differ on the left from the right?
Phrenic nerve passes with the IJV across Scalenus Anterior.
- Left: crosses anterior to the 1st part of Subclavian artery
- Right: crosses anterior to the 2nd part of the subclavian artery
Both sides, the nerve runs posterior to the subclavian vein and Internal Thoracic artery as it enters the thorax
What path does the left phrenic nerve take as it travels down the thorax?
- Passes lateral to the Left Subclavian Artery and Aortic Arch
- Then passes Anterior to the Root of the lung
- Pierces the Diaphragm
What path does the RIGHT phrenic nerve take in the mediastinum?
Travels Anterior to the Right VAGUS nerve and lateral to the SVC
Passes over the right ATRIUM and exits diaphragm at T8
What are the roots and origins of the Long Thoracic Nerve?
Derived from the Ventral Rami of C5,C6 and C7
What muscle does the Long Thoracic nerve innervate and what clinical sign is associated with damage to this nerve?
Innervates the Serratus Anterior muscle
- damage causes Winged Scapula
What is the nerve supply of the Breast?
Branches of intercostal nerves T4 - T6
What is the blood supply of the breast?
Internal mammary artery (branch of subclavian)
External mammary artery (supplies lateral)
What is the structure that suspends the spinal cord in the dural sheath?
Denticulate ligaments
What is the name of the fascia that overlies the apices of both lungs?
Sibson’s fascia
At what vertebral level does the aorta, oesophagus and vena cava traverse the diaphragm?
Aorta - T12
Oesophagus - T10
Vena cava - T8
What structure separates the subclavian artery from the vein?
Anterior scalene muscle
At what level does the trachea bifurcate?
T5
What nerve is commonly injured in axillary node clearances and what would a patient present with?
Thoracodorsal nerve
Innervates the latissumus dorsi.
Pt would present with quick fatigue of the arm of the affected side
What is the nerve supply of the oesophagus?
Upper half: Recurrent Laryngeal nerve
Lower half: Oesophageal plexus (vagus)
What are the arterial supplies of the oesophagus and it’s venous drainage?
Upper third:
- inferior thyroid artery
- inferior thyroid vein
- deep cervical lymph
Middle third:
- Aortic branches
- azygos veins
- mediastinal nodes
Lower third:
- Left gastric artery
- left gastric vein
- gastric lymph nodes
What are the 4 constrictions of the oesophagus?
1- Cricoid cartilage (15cm)
2- Arch of the aorta (22.5cm)
3- Left principal bronchus (27cm)
4- Diaphragmatic hiatus (40cm)
What are the relations of the oesophagus in the thorax?
Anteriorly:
Trachea (T4) / Recurrent laryngeal nerve / Left bronchus / Diaphragm
Posteriorly:
Thoracic duct to the left (T5) / Descending aorta
Left:
Thoracic duct / Left subclavian artery
Right: Azygos vein
What are the borders of the safety triangle (chest drain insertion)?
Mid axillary line in 5th intercostal space
- Anterior edge of Latissimus dorsi
- Lateral border of Pectoralis major
- Line superior to horizontal level of nipple
- Apex below axilla
What is the investigation of choice for upper airway compression?
Flow volume loop
What is contained within the superior mediastinum?
- SVC
- Arch of the aorta
- Trachea
- Oesophagus
- CN X
- Phrenic nerve
- Left recurrent laryngeal nerve
- Thoracic duct
- Brachiocephalic veins
What is contained within the middle mediastinum?
- Pericardium
- Heart
- Aortic root
- Arch of azygos vein
- Main bronchi
What is contained within the posterior mediastinum?
- Oesophagus
- Thoracic aorta
- Azygos vein
- Thoracic duct
- Vagus nerve
- Sympathetic nerve trunks
- Splanchnic nerves
What separates the subclavian artery from the subclavian vein and where does this structure insert?
Scalenus anterior
Runs from transverse processes of C3,4,5,6 and inserts onto Scalene tubercle of the 1st rib
