Lecture 8.3: Thoracic walls and diaphragm

Question 1

What are breasts?

Answer 1

They are a collection of mammary glands, located on the thoracic wall of females; they are part of us

Question 2

What does the bony framework of our thorax consist of?

Answer 2

Sternum, 12 thoracic vertebrae and 12 ribs

Question 3

Name the parts of the sternum and what they do

Answer 3

1. Manubrium: articulates with the clavicle
2. Body: most ribs attach here
3. Xiphoid process: cartilaginous

Question 4

What kind of bones are ribs?

Answer 4

They are flat bones

Question 5

Describe the ribs: group names, numbers, where they attach

Answer 5

First we have the ‘true’ ribs; 1-7 because they attach directly to the sternum. Then we have the ‘false’ ribs; 8-10 because they do not attach directly, rather, they attach to the superior rib. Lastly, we have the ‘floating’ ribs; 11-12, the don’t articulate with the sternum at all.

Question 6

What is the main difference between ribs 1-10 and 11-12?

Answer 6

1-10 have their own costal hyaline cartilage whereas 11-12 do not.

Question 7

Describe the structure of a typical rib; which number ribs have this similar layout?

Answer 7

Ribs 3-9

• HEAD of the rib; articulates with the vertebrae at two small impressions called the superior and inferior facets
• NECK of the rib
• TUBERCLE; with a smooth facet attaching nothing and a rough bump that attaches muscles/ligaments
• BODY; curved and vertically orientated, has a superior and an inferior border; also has the COSTAL GROOVE on the inferior border, where the “VAN” will lay!

Question 8

What are some features of the THORACIC vertebra?

Answer 8

• Longer and more verticle spinous process
• Since the T vertebra articulate with the ribs, it must have inferior and superior costal facets at the posterior end of the body
• Also articulates with the ribs at the transverse processes

Question 9

What are the joints in the thorax called? (2) Describe them.

Answer 9

1. Costovertebral: between the head of the rib and the vertebrae
2. Costotransverse: between the transverse process of the vertebra and the smooth part of the rib

Question 10

Describe the costovertebral joint in detail

Answer 10

So the head of the rib articulates with the inferior costal facet of the vertebra above, the IV disc, and also the superior costal facet of the vertebra below. WE NUMBER THE RIB BY THE VERTEBRA BELOW

Question 11

What ligament is associated with the costovertebral joint? describe it

Answer 11

The RADIATE ligament; ‘radiating’ around all the articulating points of the costovertebral joint

Question 12

What ligament is associated with the costotransverse joint? describe it

Answer 12

There are 3 but we are focusing only on the lateral costotransverse ligament; it joins the transverse process and the rough part of the rib tubercle

Question 13

What are apertures?

Answer 13

An opening, hole, or gap

Question 14

Name and describe the thoracic apertures we have

Answer 14

1. Superior aperture; hole is formed by the superior part of the manubrium, the inferior walls of the first pair ribs, and the superior part of the T1 vertebra
2. Inferior aperture: larger hole formed by the xiphoid process of the sternum, the costal margin, the inferior border of the 12th rib and the T12 vertebra.

Question 15

Describe the closing off/opening of the superior and inferior aperture.

Answer 15

Superior: partially closed by the suprapleural membrane
Inferior: completely closed off by a muscle called the DIAPHRAGM

Question 16

What is the costal margin?

Answer 16

It’s the upside down shape V when you look at the rib cage

Question 17

Describe the peripheral attachments of the diaphragm

Answer 17

• The xiphoid process
• Costal margin
• 11th and 12th ribs
• The arcuate ligaments
• The lumbar vertebral body via left an right vrus

Question 18

Describe how the diaphragm sits in the body

Answer 18

It has two domes; the right side (on your own body) is higher than the left due to placement of the liver. These domes attach to the LUMBAR vertebra via CRURA, which are ligaments.

Question 19

Describe the ligaments of the disphragm.

Answer 19

The right crus is longer as the right dome sits higher; this crus attaches to L1-L3.
The left crus attaches L1-L2

Question 20

What is the central tendon?

Answer 20

In the middle of the diaphragm, is a sheet of pearly white fibrous tissue… does not have any bony attachments

Question 21

How does the diaphragm help with breathing?

Answer 21

Its contraction increases the volume of the thorax and so inflates the lungs.

Question 22

What are hiatuses?

Name the ones we have

Answer 22

They are three large holes found in the diaphragm that provides a pathway for structures running through the thorax

1. IVC: inferior vena caval
2. Oesophagus
3. Aortic

Question 23

Describe the nervous innervation of the diaphragm

Answer 23

Motor: supplied by the phernic nerves, left and right
Sensory: supplied by intercostal and subcostal nerves

Question 24

Describe and name the intercostal space

Answer 24

The space between the ribs. 3 layers.

1. External
2. Internal
3. Innermost

Question 25

Describe the external intercostal space

Answer 25

Outermost layer, fibres in a ‘pocket’ direction, when they contract they pull the ribs up and out

Question 26

Describe the internal intercostal space

Answer 26

fibres run opposite to pocket, don’t really help with anything

Question 27

Describe the innermost intercostal space

Answer 27

patchy and have altering fibre directionality

Question 28

What is the neuromuscular bundle?

Answer 28

Found in the COSTAL GROOVE of the ribs; VEINS, ARTERY, NERVES; V.A.N

Question 29

If you hear the word “intercostal”, what should you automatically think of?

Answer 29

Atomical features between the space of the ribs

Question 30

Describe the intercostal nerves/arteries/veins

Answer 30

Nerves: originate from anterior rami of spinal nerves
T1-T11. Runs between the middle and deepest layer; also branches
Artery/veins: arises both anterior and posterior. provides blood to intercostal muscles and thoracic walls. Each artery is paired with a vein

Question 31

Describe the movements of the thorax

Answer 31

Can be changed by muscle:

1. Vertically; up/down by diaphragm
2. Front/back (AP); contraction of 1-7 rib because they push the sternum outwars
3. Lateral (Left/right); external intercostal muscles of ribs 8-10; since they don’t directly articulate with the sternum, it pushes laterally.