chest wall

Question 1

Which nerve innervates the serratus anterior muscle?

A. Thoracodorsal nerve
B. Long thoracic nerve
C. Intercostal nerve
D. Medial pectoral nerve
E. Lateral pectoral nerve

Answer 1

B. Long thoracic nerve

The serratus anterior is innervated by the long thoracic nerve, which arises from the roots of C5–C7. It travels on the surface of the muscle — which is clinically important because it can be damaged easily during surgery, leading to a winged scapula.

Question 2

Which vertebra forms the posterior boundary of the superior thoracic aperture?

A. T12
B. C7
C. T1
D. T2
E. L1

👉 What’s your answer?

Answer 2

C . The T1 vertebra forms the posterior boundary of the superior thoracic aperture, also called the thoracic inlet.

Question 3

What feature is found at the manubriosternal joint and used as a surface landmark?

A. Costal margin
B. Jugular notch
C. Sternal angle
D. Xiphoid process
E. Clavicular notch

👉 What’s your answer?

Answer 3

c.✅ Correct again!
The sternal angle (also called the angle of Louis) is located at the manubriosternal joint and is an important surface landmark—used for rib counting (marks the level of the 2nd rib) and several anatomical transitions.

Question 4

Which rib is associated with the sternal angle for rib counting?

A. First
B. Second
C. Third
D. Fifth
E. Seventh

👉 Your answer?

Answer 4

B.
✅ Correct!
The second rib articulates at the sternal angle, which is why it’s used as the key landmark for rib and intercostal space counting.

Question 5

Question 4
Which structure is NOT typically associated with the thoracic outlet boundary?

A. Xiphisternal joint
B. 1st pair of ribs
C. T12 vertebra
D. Costal cartilages of ribs 7–10
E. 11th and 12th ribs

👉 What’s your answer?

Answer 5

B.
✅ Correct!
The 1st pair of ribs is part of the superior thoracic aperture, not the thoracic outlet (inferior aperture). The xiphisternal joint, T12, ribs 7–12, and costal cartilages are all components of the thoracic outlet.

Question 6

Question 5
Which costal movement mechanism is primarily associated with upper ribs?

A. Hinge-like movement
B. Bucket-handle movement
C. Sliding movement
D. Pump-handle movement
E. Axial rotation

👉 Your answer?

Answer 6

D.
✅ Spot on!
Upper ribs (especially ribs 2–6) move with a pump-handle motion during inspiration, increasing the anterior-posterior diameter of the thorax.

Question 7

Question 6
Which muscle attaches from the ribs 3–5 to the coracoid process and assists respiration?

A. Serratus anterior
B. Pectoralis major
C. Pectoralis minor
D. Scalene
E. Rectus abdominis

👉 Your answer?

Answer 7

C.
✅ Correct!
Pectoralis minor originates from ribs 3–5 and inserts on the coracoid process. When the shoulder girdle is fixed, it acts as an accessory muscle of respiration.

Question 8

where does pectoralis minor originate from?

Answer 8

ribs 3-5 and inserts on the coracoid process

Question 9

Question 10
Which nerve innervates the serratus anterior muscle?

A. Thoracodorsal nerve
B. Long thoracic nerve
C. Intercostal nerve
D. Medial pectoral nerve
E. Lateral pectoral nerve

Answer 9

Long thoracic nerve

The serratus anterior is innervated by the long thoracic nerve, which arises from the roots of C5–C7. It travels on the surface of the muscle — which is clinically important because it can be damaged easily during surgery, leading to a winged scapula.

Question 10

Question 11
The diaphragm increases intrathoracic volume during:

A. Forced expiration
B. Passive expiration
C. Inspiration
D. Swallowing
E. Sneezing

👉 What’s your answer?

Answer 10

C. Inspiration

The diaphragm contracts during inspiration, pulling downward and increasing intrathoracic volume. This creates negative pressure that draws air into the lungs.

Expiration is usually passive, especially at rest, due to elastic recoil of the lungs and diaphragm.

Question 11

Question 12
Which of the following structures does not pass through the superior thoracic aperture?

A. Trachea
B. Aorta
C. Oesophagus
D. Subclavian artery
E. Phrenic nerve

Answer 11

B. Aorta

The aorta does not pass through the superior thoracic aperture (aka the thoracic inlet). Instead, it starts lower down, becoming the arch of the aorta after exiting the left ventricle, and descends into the thorax behind the heart.

The trachea, oesophagus, phrenic nerve, and subclavian artery all pass through the superior thoracic aperture.

Question 12

Question 13
What separates the internal intercostal and innermost intercostal muscles?

A. Costal cartilage
B. Parietal pleura
C. Intercostal neurovascular bundle
D. Endothoracic fascia
E. Pericardium

👉 What’s your answer?

Answer 12

✅ Correct!

The intercostal neurovascular bundle (Vein, Artery, Nerve — VAN) separates the internal intercostal from the innermost intercostal muscles. This bundle lies in the costal groove of the rib above, making it an important area to be cautious of during procedures like chest drains or nerve blocks.

Question 13

Question 14
Which joint type is found at the manubriosternal junction?

A. Synovial
B. Hinge
C. Syndesmosis
D. Symphysis
E. Synchondrosis

Answer 13

D. Symphysis

The manubriosternal joint is a secondary cartilaginous joint, also called a symphysis. It’s slightly movable and becomes ossified with age. It forms the sternal angle, an important surface landmark.

Question 14

The posterior intercostal arteries for ribs 3–11 arise from the:

A. Aortic arch
B. Subclavian artery
C. Internal thoracic artery
D. Thoracic aorta
E. Musculophrenic artery

Answer 14

D. thoracic aorta

The posterior intercostal arteries for ribs 3–11 arise directly from the thoracic aorta, which runs down the posterior thorax after the arch of the aorta.

Question 15

Which structure drains into the azygos vein on the right side?

A. 1st posterior intercostal vein
B. Left superior intercostal vein
C. Subcostal vein
D. Internal thoracic vein
E. Musculophrenic vein

Answer 15

C. Subcostal vein

The subcostal vein, which lies beneath the 12th rib, drains into the azygos vein on the right side. On the left, it drains into the hemiazygos vein, which then crosses over to join the azygos vein.

The internal thoracic vein instead drains anterior intercostal veins into the brachiocephalic vein — part of the anterior venous system, not the posterior azygos system.

Question 16

Question 18
The accessory hemiazygos vein drains which intercostal spaces on the left side?

A. 1–4
B. 5–8
C. 4–11
D. 9–12
E. 3–6

👉 What’s your answer?

Answer 16

B. 5–8

The accessory hemiazygos vein is found on the left side of the thorax and drains the 5th to 8th posterior intercostal veins. It then crosses to the right and joins the azygos vein, which ultimately drains into the superior vena cava (SVC).

Question 17

Which spinal nerves contribute to the intercostal nerves?

A. Ventral rami of cervical nerves
B. Dorsal rami of thoracic nerves
C. Anterior rami of thoracic nerves
D. Posterior rami of lumbar nerves
E. Anterior rami of lumbar nerves

Answer 17

C.
The intercostal nerves come from the anterior (ventral) rami of the thoracic spinal nerves — specifically T1 to T11. These nerves run in each intercostal space and innervate the intercostal muscles and overlying skin.

Question 18

The internal thoracic artery gives rise to anterior intercostal arteries for which rib spaces?

A. 1–9
B. 1–6
C. 1–5
D. 7–9
E. 1–12

Answer 18

B. 1–6

The internal thoracic artery gives rise to anterior intercostal arteries for the 1st to 6th intercostal spaces.
For the 7th to 9th, the anterior intercostals come from the musculophrenic artery, which is a branch of the internal thoracic.

Question 20

Where do the 1st and 2nd posterior intercostal arteries arise from?

Answer 20

From the superior intercostal artery, which branches from the costocervical trunk (a branch of the subclavian artery).

Question 21

What is the source of the 12th intercostal artery?

Answer 21

The thoracic aorta — it’s called the subcostal artery.

Question 22

What do the lateral cutaneous branches of intercostal nerves supply?

Answer 22

Skin on the lateral chest wall.

Question 23

Which muscle layer lies deepest in the intercostal space?

Answer 23

Innermost intercostal muscle.

Question 24

Which venous system drains the anterior chest wall?

Answer 24

Internal thoracic → brachiocephalic vein system.

Question 25

Where do the 1st to 6th anterior intercostal arteries arise from?

Answer 25

From the internal thoracic artery.

Question 26

Where does the hemiazygos vein drain into?

Answer 26

The azygos vein.

Question 27

What is the role of grey ramus communicans?

Answer 27

Returns postganglionic sympathetic fibres to the spinal nerve.

Question 28

What is the role of white ramus communicans?

Answer 28

Carries preganglionic sympathetic fibres to the sympathetic chain.

Question 29

Which venous system drains the posterior chest wall?

Answer 29

Azygos system.

Question 30

What does 'somatic efferent' mean?

Answer 30

Motor signals from spinal cord to skeletal muscles.

Question 31

How are intercostal spaces named?

Answer 31

By the rib that forms their superior border.

Question 32

Which intercostal muscle is most active during inspiration?

Answer 32

External intercostal muscle.

Question 33

What runs in the costal groove of a typical rib?

Answer 33

VAN — Vein, Artery, Nerve (superior to inferior).

Question 34

What is the name of the T12 intercostal nerve?

Answer 34

The subcostal nerve.

Question 35

Where do sympathetic fibres in the intercostal nerves come from?

Answer 35

From the sympathetic chain via the grey rami communicantes.

Question 36

Where does the azygos vein receive blood from?

Answer 36

Posterior intercostal veins on the right side (5th to 11th), hemiazygos, and accessory hemiazygos veins.

Question 37

What is the direction of internal intercostal muscle fibres?

Answer 37

Postero-inferiorly, at right angles to external intercostals.

Question 38

Where does the intercostal neurovascular bundle lie?

Answer 38

Between the internal and innermost intercostal muscles.

Question 39

What is the main action of all intercostal muscles?

Answer 39

To keep intercostal spaces rigid during respiration.

Question 40

Where do the 7th to 9th anterior intercostal arteries come from?

Answer 40

From the musculophrenic artery, a branch of the internal thoracic.

Question 41

Where does the right superior intercostal vein drain?

Answer 41

Into the azygos vein.

Question 42

Which intercostal spaces does the hemiazygos vein drain?

Answer 42

9th to 12th posterior intercostal spaces on the left.

Question 43

Where do the 2nd and 3rd posterior intercostal veins drain?

Answer 43

They form the superior intercostal vein.

Question 44

What are intercostal nerves derived from?

Answer 44

The anterior (ventral) rami of thoracic spinal nerves T1–T11.

Question 45

Which intercostal spaces does the accessory hemiazygos vein drain?

Answer 45

5th to 8th posterior intercostal spaces on the left.

Question 46

What do the anterior cutaneous branches of intercostal nerves supply?

Answer 46

Skin on the anterior chest wall.

Question 47

What does the internal thoracic artery branch off from?

Answer 47

The subclavian artery.

Question 48

What is the path of blood from the heart to anterior intercostal arteries?

Answer 48

Left ventricle → ascending aorta → aortic arch → subclavian artery → internal thoracic → anterior intercostals.

Question 49

What does 'somatic afferent' mean?

Answer 49

Sensory signals from skin/muscles to the spinal cord.

Question 50

Where does the 1st posterior intercostal vein drain?

Answer 50

Directly into the brachiocephalic vein.

Question 51

Where does the left superior intercostal vein drain?

Answer 51

Into the left brachiocephalic vein.

Question 52

Where does the accessory hemiazygos vein drain into?

Answer 52

The azygos vein.

Question 53

What is the direction of external intercostal muscle fibres?

Answer 53

"Hands in pockets" – anteroinferiorly.

Question 54

Where do the 3rd to 11th posterior intercostal arteries arise from?

Answer 54

Directly from the thoracic aorta.

Question 55

Where do the anterior intercostal veins drain?

Answer 55

Into the internal thoracic vein.

Question 56

What do the muscular branches of intercostal nerves do?

Answer 56

Innervate intercostal muscles.

Question 57

Where does the internal thoracic vein drain?

Answer 57

Into the brachiocephalic vein.

Question 58

What is the path of blood from the heart to the posterior intercostal arteries?

Answer 58

Left ventricle → ascending aorta → aortic arch → thoracic aorta → posterior intercostal arteries.

Question 59

what sort of joint is the manubrial sternal join

Answer 59

symphysis

Question 60

what sort of joint is the xihpisternal joint

Answer 60

synchondrosis

Question 61

What is the main function of the pectoralis major muscle? 2 functions?

Answer 61

- Adduct the humerus. - Rotate the arm. also Can help to raise the chest, hence helping breathing.

Question 62

What is the primary function of the ‘serratus anterior’?

Answer 62

Helps to move the scapula. , can also help to elevate the chest, to help with inspiration.

Question 63

What is the function of the ‘rectus abdominis’?

Answer 63

flexion of the trunk also helps To depress the ribcage, helping in forced expiration.

Question 64

What are the two muscles which help to counteract the excessive downwards displacement of the ribs due to gravity?

Answer 64

- Scalenes muscle The scalenes muscles attach to the 1st and 2nd ribs distally, and whenever an excessive downwards force is applied, they contract to prevent the excessive depression of the ribs. - Sterno-cleidomastoid muscle The ‘sterno-cleidomastoid’ muscle is attached to the sternum, clavicle and the mastoid process (on the skull). Hence as an accessory function it is able to support the rib cage against excessive downwards depression.