Thoracic Skeleton, Ventilation & Thoracic Wall

Question 1

What is the function of the thoracic skeleton?

Answer 1

• attachment for upper limb muscles (bony landmarks)
• protection and landmarks to the underlying viscera of the thorax (heart & lungs) and superior abdominal cavity
• openings for communication with superior and inferior region (aperatures)
• movement for respiration (ribs)

Question 2

What 3 bones make up the sternum?

Answer 2

Manubrium
Body
Xiphoid process

Question 3

What internal structures make up the sternal angle?

Answer 3

superior and inferior mediastinum

Question 4

Where is the sternal angle found in the transverse thoracic plane?

Answer 4

between T4 & T5

Question 5

Where is the sternocostal joint?

Answer 5

Between the sternum and the costal cartilage

Question 6

where is the costochondral joint?

Answer 6

between the costal cartilage and the ribs

Question 7

what is the function of costal cartilage?

Answer 7

increases elasticity of the structure

better for movement

Question 8

What are the true ribs?

Answer 8

Ribs 1-7

Question 9

What are the false ribs?

Answer 9

ribs 8-10 (attaches to the superior costal cartilage)

Question 10

what are the floating ribs?

Answer 10

ribs 11 & 12 (attaches to T11 and T12 vertebral bodies)

Question 11

Where is the costal margin located?

Answer 11

inferior boundary anterior thoracic wall

Question 12

what does the costal margin do?

Answer 12

attachment for diaphragm and abdominal wall muscles

Question 13

Where is the costovertebral joints located?

Answer 13

between the vertebral body and rib (costal facet)

Question 14

where is the costotransverse joint located?

Answer 14

between the tubercle of rib with the transverse process

Question 15

What does the tubercle of rib 5 articulate with?

Answer 15

• transverse process of T5

Question 16

What is the relationship between the rib and vertebral body?

Answer 16

number rib attaches to same number vertebral body

Question 17

What does the head of rib 5 articulate with?

Answer 17

superior costal facet of T4
interior costal facet of T5
T4/T5 intervertebral disc

Question 18

what is unique about the 1st rib?

Answer 18

only has one articulation - T1 vertebrae

Question 19

where is the costal groove located and why is it significant?

Answer 19

located on inferior border of rib and the intercostal neurovascular bundle can be found here

Question 20

what is the weakest part of the rib?

Answer 20

anterior to the angle - many trauma related fractures occur here

Question 21

why are rib fractures painful?

Answer 21

• can puncture the lining resulting in pneumothorax

- neurovascular bundle is located within the costal groove

Question 22

what is the order of the neurovascular bundle?

Answer 22

rib –> thoracic wall
Vein
Artery
Nerve

[muscle]

Nerve
Artery
Vein
(rib)

Question 23

describe the location of the superior thoracic aperature

Answer 23

1st rib, T1 vertebra, jugular notch of sternum

Question 24

describe the passageway for vital structures in and out of the thoracic cavity to the superior thoracic aperature

Answer 24

thoracic cavity neck

thoracic cavity upper limb

Question 25

describe the passageway for vital structures in and out of the thoracic cavity to the inferior thoracic aperture

Answer 25

thoracic cavity abdominal cavity

Question 26

describe the location of the inferior thoracic aperature

Answer 26

enclosed by the diaphragm

Question 27

during inhalation and exhalation, how do the structures move?

Answer 27

everything moves up and down together

Question 28

What happens to the thoracic skeleton during inhalation?

Answer 28

volume increases pressure decreases ribs move up and out diaphragm flattens

Question 29

what happens to the thoracic cavity during exhalation?

Answer 29

volume decreases pressure increases ribs fall diaphragm moves up

Question 30

what nerve innervates the diaphragm?

Answer 30

phrenic nerve (C3, C4, C5)

Question 31

where does the diaphragm sit at the right dome?

Answer 31

liver inferior | level of the 5th rib at rest

Question 32

where does the diaphragm sit at the left dome?

Answer 32

stomach and spleen inferior | level of the 5th intercostal space at rest

Question 33

what is the superior attachment of the diaphragm?

Answer 33

central tendon

Question 34

what are the functions of the diaphragm?

Answer 34

- separates thoracic cavity and abdominal cavity - encloses inferior thoracic aperture - primary muscle for ventilation

Question 35

what are the inferior attachments to the diaphragm?

Answer 35

- xiphoid process of sternum - costal margin - ends of ribs 11 and 12 - arcuate ligaments across posterior wall - lumbar vertebrae

Question 36

What major structure passes through the caval opening/vena caval hiatus and at what level?

Answer 36

Inferior vena cava | Level T8

Question 37

what major structure passes through the esophageal hiatus and at what level?

Answer 37

Esophagus | Level T10

Question 38

what major structure passes through the aortic hiatus and at what level?

Answer 38

thoracic aorta | level T12

Question 39

what other structures pass through the caval opening?

Answer 39

right phrenic nerve

Question 40

what other structures pass through the esophageal hiatus?

Answer 40

vagal trunks

Question 41

what other structures pass through the aortic hiatus?

Answer 41

azygos vein thoracic duct sympathetic trunks

Question 42

what are the accessory muscles used in forced inspiration?

Answer 42

``` external intercostals neck muscles (sternocleidomastoid and scalene group) ```

Question 43

what are the accessory muscles of expiration?

Answer 43

``` internal intercostals abdominal muscles (external oblique and rectus abdominus) ```

Question 44

name the thoracic wall muscles

Answer 44

``` pec major pec minor serratus anterior sternocleidomastoid anterior, middle, posterior scalenes external oblique rectus abdominus ```

Question 45

name the true muscles of thoracic wall (muscles directly on the ribs)

Answer 45

transversus thoracis subcostal (found in between each rib) serratus posterior superior and inferior levatores costarum longus and brevis

Question 46

what are the functions of the intercostal muscles?

Answer 46

- maintain structure of thoracic wall - rib movement during respiration - inner layers enclose neurovascular bundle

Question 47

what does the external intercostal layer do and what way does the fibers run?

Answer 47

- elevates ribs during inspiration | - fibers run hands in pockets

Question 48

where is the external intercostal membrane located?

Answer 48

sternum anteriorly

Question 49

what does the internal intercostal muscles do and which way does the fibers run?

Answer 49

- depress ribs during exhalation | - "oh my" muscle fiber direction

Question 50

where is the internal intercostal membrane located?

Answer 50

vertebral bodies posteriorly

Question 51

which intercostal muscle layer is the most deep and has same fiber direction as the internal layer?

Answer 51

innermost intercostal muscles

Question 52

between which layers are the intercostal vein, artery and nerve found?

Answer 52

between internal and innermost layers - innermost does not have intercostal membrane

Question 53

describe the posterior intercostal vein system

Answer 53

posterior intercostal veins drain into azygos vein accessory hemi-azygos vein and hemi-azygos vein drain into azygos vein azygos vein drains into the superior vena cava superior vena cava branches to the right and left brachiocephalic veins

Question 54

at superior levels where does the posterior intercostal veins sometimes drain into?

Answer 54

straight into the brachiocephalic vein

Question 55

describe the anterior vein drainage

Answer 55

anterior intercostal veins drain into internal thoracic veins internal thoracic veins drain into brachiocephalic veins

Question 56

which two main sources does the intercostal arteries originate from?

Answer 56

subclavian artery | thoracic aorta

Question 57

describe the anterior drainage from the subclavian artery

Answer 57

suclavian artery supplies blood to the internal thoracic artery internal thoracic artery supplies blood to anterior intercostal arteries

Question 58

describe the posterior blood supply of the subclavian artery

Answer 58

subclavian artery supplies blood to costocervical trunk | costocervical trunk supplies blood to 1st and 2nd posterior intercostal arteries

Question 59

describe the blood supply from the thoracic aorta

Answer 59

thoracic aorta supplies blood to posterior intercostal arteries (T3-T11) AND subcostal artery (T12)

Question 60

where do the intercostal and subcostal nerves arise from?

Answer 60

anterior rami of thoracic spinal nerves

Question 61

describe the pathway of the intercostal nerve

Answer 61

intercostal nerve --> lateral cutaneous branch --> anterior cutaneous branch

Question 62

what is the motor innervation of the intercostal nerve?

Answer 62

intercostal mm transversus thoracis mm subcostal mm rectus abdominus and external oblique (abdominal wall muscles)

Question 63

what is the sensory innervation for the intercostal nerves?

Answer 63

skin at each thoracic nerve level (dermatomes) - can overlap 1-2 dermatome levels lower thoracic nerves (T6-T11) and subcostal nerve cross the costal margin

Question 64

what does sympathetic innervation in the periphery do?

Answer 64

- activate sweat glands - cause hair follicles to stand on end - vasoconstricts blood vessels in the skin

Question 65

what is involved in the sympathetic pathway?

Answer 65

sympathetic chain - will see its location in the posterior mediastinum