L-02-Thoracic-Wall-Muscles

Question 1

Thoracic Muscles
Q: What are the extrinsic muscles of the thorax?
Q: What are the intrinsic (intercostal) muscles of the thorax?

Answer 1

A: Pectoralis major, Pectoralis minor, Serratus anterior
A: External intercostals, Internal intercostals, Innermost intercostals, Transversus thoracis

Question 2

Intercostal Muscles
Q: What is the main function of intercostal muscles?
Q: What is the difference between external and internal intercostal muscles?

Answer 2

A: Assist in respiration by moving the ribs
A:

External intercostals: Elevate ribs during inhalation
Internal intercostals: Depress ribs during forced exhalation

Question 3

Intercostal Spaces
Q: How many intercostal spaces are there?
Q: What structures are found in the intercostal spaces?

Answer 3

A: 11 intercostal spaces (since there are 12 ribs)

A: Intercostal muscles, arteries, veins, nerves, and lymphatics

Question 4

Neurovascular Bundle
Q: What is the order of structures in the neurovascular bundle?
Q: Why is it important to insert needles low in the intercostal space?

Answer 4

A: Vein (V), Artery (A), Nerve (N) from top to bottom
A: To avoid damaging the neurovascular bundle, which runs high in the space

Question 5

Diaphragm
Q: What is the primary function of the diaphragm
Q: What are the three major openings in the diaphragm and their levels?

Answer 5

A: It is the main muscle of respiration

A:

1.Inferior vena cava opening (T8) – Transmits vena cava, right phrenic nerve, and lymphatics

2.Esophageal hiatus (T10) – Transmits esophagus and vagus nerves

3.Aortic opening (T12) – Transmits aorta, thoracic duct, and splanchnic nerves

Question 6

Nerve Supply of the Diaphragm
Q: What is the motor nerve supply of the diaphragm?
Q: What are the sensory nerve supplies of the diaphragm?

Answer 6

A: Phrenic nerve (C3-C5)

A:

Centrally: Phrenic nerve
Peripherally: Lower five intercostal nerves

Question 7

Functions of the Diaphragm
Q: Besides respiration, what other functions does the diaphragm have?

Answer 7

A:

Assists in vomiting, defecation, and urination by increasing intra-abdominal pressure
Prevents acid reflux by exerting pressure on the esophagus
Assists in weightlifting by stabilizing intra-abdominal pressure

Question 8

Mechanism of Respiration
Q: What muscles are involved in quiet respiration?
Q: What muscles are involved in forced inhalation?
Q: What muscles are involved in forced exhalation?

Answer 8

A: Diaphragm and external intercostal muscles
A: Sternocleidomastoid, scalene muscles, and pectoralis minor
A: Internal intercostal muscles and abdominal muscles

Question 9

Clinical Aspects

Q: What condition can result from phrenic nerve damage?

Answer 9

A: Phrenic nerve palsy, leading to an elevated hemidiaphragm on a chest X-ray