Thorax 1.2

Question 1

What does the spinal nerve divide into?

Answer 1

into a small posterior ramus that supplies the intrinsic muscles of the back and a larger anterior ramus (intercostal nerve) that innervates all the muscles lining the trunk

Question 2

What does the anterior ramus divide into?

Answer 2

• a lateral cutaneous branch at the midaxillary line

- anteriorly, and lateral to the sternum, it gives rise to an anterior cutaneous branch

Question 3

Where do the intercostal nerves course?

Answer 3

• between the internal intercostal and innermost intercostal muscles
• Intercostal arteries and veins accompany the intercostal nerves

Question 4

What do the first 11 thoracic nerves give rise to?

Answer 4

anterior rami that constitute the intercostal nerves (T12 is the subcostal nerve, and it is inferior to the 12th rib)

Question 5

Where do thoracic anterior rami run? Why is this important?

Answer 5

1. Thoracic anterior rami (intercostal nerves) run in the costal groove at the inferior margin of each rib
2. physicians must be aware of this positioning when entering the intercostal space (for injections or chest tube placements).

Question 6

What is the cardiac muscle of the hear innervated by?

Answer 6

The autonomic nervous system

Question 7

Where do the sympathetic contributions to the cardiac plexus arise from?

Answer 7

1. from cardiac nerves that originate largely from the cervical portions of the sympathetic trunk (although their preganglionic fibers arise from neurons in the upper 4 thoracic spinal cord levels)
2. but also send direct thoracic cardiac branches (postganglionic sympathetics) medially toward the heart

Question 8

Where do the parasymapthetic contributions to the heart travel?

Answer 8

(preganglionic) travel with the vagus nerve (CN X)

Question 9

What is the cardiac plexus formed from?

Answer 9

• the parasympathetic and sympathetic branches form a rich cardiac plexus around the great vessels arising from the heart and around the bifurcation of the trachea.
• The vagus preganglionics synapse on postganglionics in this plexus

Question 10

What does sympathetic and parasympathetic innervation to the heart do?

Answer 10

1. Sympathetic innervation to the heart increases the heart rate and contractile force 2. Parasympathetic innervation decreases the heart rate

Question 11

Where is angia pectoris conveyed? Where is the referred pain?

Answer 11

1. Pain sensation from myocardial ischemia, called angina pectoris, is conveyed to the upper 4 thoracic spinal cord levels via the sympathetic pathways
2. accounting for referred pain over the T1-T4 dermatome regions, primarily on the left side. 3. This pain may be initially interpreted by the patient as somatic pain (musculoskeletal) rather than pain from the ischemic cardiac muscle of the heart

Question 12

What type fo nerves are of the oesophagus and posterior thoracic wall?

Answer 12

somatic nerves (thoracic intercostal nerves) and autonomic nerve

Question 13

What do thoracic spinal cord segments give rise to?

Answer 13

intercostal nerves, which are connected by rami communicantes to the sympathetic trunk

Question 14

What happens in the thorax?

Answer 14

the latter gives rise to the greater, lesser, and least splanchnic nerves (all preganglionic sympathetics), which course through the diaphragm to the abdomen

Question 15

What is the parasympathetic contribution of the oesophagus and posterior thoracic wall?

Answer 15

• via the vagus nerve

- As they pass through the diaphragm, the left and right vagus nerves form a plexus on the esophagus

Question 16

What would a mass in posterior mediastinum present as?

Answer 16

• pain, neurologic symptoms, or difficulty swallowing (dysphagia)
• The most common masses include tumors of the peripheral nerves or their sheath cells (e.g., schwannomas), or tumors or diverticula of the esophagus

Question 17

Where do posterior intercostal arteries arise from and course?

Answer 17

• from the thoracic aorta bilaterally

- course along the inferior margin of each rib between the innermost intercostal muscles and internal intercostal muscle

Question 18

What happens at the midaxillary line?

Answer 18

these intercostal vessels give rise to a lateral cutaneous artery

Question 19

What do the intercostal vessels do anteriorly?

Answer 19

anastomose with the anterior intercostal arteries arising from the internal thoracic (mammary) artery

Question 20

What do the intercostal veins and nerves course with?

Answer 20

ith the intercostal arteries

Question 21

Where should injections and tubes be placed?

Answer 21

1. Because of the location of the major intercostal neurovascular bundle (nerve, artery, and vein) just inferior to each rib (costal groove)
2. any injections or tubes placed into the intercostal space should be positioned closer to the superior edge of the rib margin to avoid piercing the neurovascular bundle.

Question 22

What forms the right and left brachiocephalic veins?

Answer 22

The union of the internal jugular veins, which drain the head and neck region, and the subclavian veins, which drain the upper limbs

Question 23

What do the 2 brachiocephalic veins join to form?

Answer 23

the superior vena cava

Question 24

Where does the pulmonary trunk receive blood from?

Answer 24

the right ventricle and divides into right and left pulmonary arteries

Question 25

Where does the ascending aorta recipe blood from?

Answer 25

the left ventricle and arches over the pulmonary trunk, continuing inferiorly as the thoracic aorta

Question 26

What can cardiac tamponade result from?

Answer 26

fluid accumulation or bleeding into the pericardial cavity. The accumulated fluid can compromise the heart's ability to contract and relax effectively, thus decreasing venous return and cardiac output

Question 27

Where does the right coronary artery arise from?

Answer 27

the ascending aorta

Question 28

What does the right coronary artery supply?

Answer 28

1. the right atrium 2. most of the right ventricle 3. the diaphragmatic surface of the left ventricle 4. part of the atrioventricular septum 5. the sinuatrial node (60% of the time) 6. the atrioventricular node (80% of the time)

Question 29

What does the left coronary artery arise from?

Answer 29

the ascending aorta

Question 30

What does the left coronary artery supply?

Answer 30

1. the left atrium 2. most of the left ventricle 3. some of the right ventricle 4. most of the interventricular septum 5. the sinuatrial node (40% of the time) 6. and the atrioventricular node (20% of the time).

Question 31

What is the coronary sinus? Where does it receive blood from?

Answer 31

- The coronary sinus is the largest vein draining the heart | - It receives blood from the great, middle, and small cardiac veins and drains into the right atrium.

Question 32

What leads to cardiac ischemia and potential myocardial infarction?

Answer 32

Forty percent to 50% of cases of coronary artery occlusion lead to cardiac ischemia and potential myocardial infarction in the proximal portion of the left anterior descending branch of the left coronary artery

Question 33

What is the thoracic aorta?

Answer 33

the direct continuation of the arch of the aorta

Question 34

What does the thoracic aorta give rise to?

Answer 34

1. to bronchial 2. esophageal 3. pericardial 4. mediastinal 5. posterior intercostal 6. subcostal 7. superior phrenic arteries.

Question 35

What is in the posterior mediastinum?

Answer 35

The esophagus and descending thoracic aorta are in the posterior mediastinum, deep to the heart, which lies in the middle mediastinum

Question 36

What lies posterior to the oesophagus?

Answer 36

the thoracic lymphatic duct

Question 37

What do the small bronchial arteries do?

Answer 37

The small bronchial arteries (usually 1 right and 2 left arteries) are the nutritive arteries, delivering essential nutrients and oxygen to the pulmonary visceral pleura, bronchi and bronchial glands, connective tissue of the lungs, and walls of the larger intrapulmonary arteries

Question 38

Where is the azygos venous system?

Answer 38

ies on either side of the vertebral column and drains deep structures of the back, thoracic wall, and abdominal walls

Question 39

What does the azygous venous arise from?

Answer 39

arises from the inferior vena cava or right ascending lumbar vein, and the hemiazygos vein (the principal tributary of the azygos vein) arises from the left ascending lumbar vein or renal vein

Question 40

Where does the azygous system drain?

Answer 40

most of the blood from the azygos system drains into the superior vena cava

Question 41

What does the azygous venous system form?

Answer 41

The azygos venous system forms an important venous conduit between the inferior vena cava and the superior vena cava

Question 42

Does the azygous venous system have valves?

Answer 42

The azygos veins do not contain valves, so blood flow may occur in different directions depending on where the pressure is highest

Question 43

What is azygous venous system a large component in?

Answer 43

Via its connections with the left gastric vein in the abdomen, the azygos system is an important component of the portosystemic anastomosis in conditions such as portal hypertension