Lecture 34 - Thoracic walls and diaphragm

Question 1

What are the functions of the thorax?

Answer 1

o Breathing
o Protection
o Passageway

Question 2

Name and describe the features of the bones contributing to the thoracic cage

Answer 2

o Thoracic vertebrae (12)
o Ribs (12 pairs)
 True ribs (1-7)
 False ribs (8-10)
 Floating ribs (11-12)
o Sternum
 Manubrium
 Body
 Xiphoid process

Question 3

Describe the thoracic vertebrae

Answer 3

o Twelve vertebral bones characterised by additional articular surfaces for the ribs
o Heart-shaped, two small demi facets for articulation with heads of ribs
o Transverse process has facet for articulation with tubercle of rib
o Long, thin, overlapping spinous processes

Question 4

What are true ribs?

Answer 4

Attach directly to the sternum

Question 5

what are false ribs?

Answer 5

attach via costal cartilage of rib

Question 6

What are floating ribs?

Answer 6

Only attached to vertebral column

Question 7

What are typical ribs?

Answer 7

o Ribs 3-9
o Anterior end
 Continuous with costal cartilage
o Posterior end
 Head = articulates with thoracic vertebrae
 Two articular surfaces for its own and the superior vertebrae
o Costal surface
 Internal surface
 Marked with the costal groove
o External surface
 Palpable

Question 8

what are the atypical ribs?

Answer 8

ribs 1, 2, 10, 11, 12

Question 9

Why is rib 1 atypical?

Answer 9

o Flat, almost horizonal
o Only articulates with T1
o Superior surface marked with grooves for arteries and veins

Question 10

Why is rib 2 atypical?

Answer 10

also flat like rib 1

Question 11

Why is rib 10 atypical?

Answer 11

Only articulates with T10 vertebra

Question 12

Why are ribs 11 and 12 atypical?

Answer 12

o Only articulate with their own vertebrae
o Do not curve around torso
o Do not connect at costal cartilage
o Project slightly anteriorly

Question 13

What are the joints of the thorax

Answer 13

o Costovertebral + costotransverse
o Costochondral
o Sternocostal
o Interchondral
o Sternal symphyses

Question 14

Costovertebral + costotransverse joints

Answer 14

o Between ribs and vertebrae
o Multiple articulations
o Separate synovial compartments

Question 15

Costochondral joints

Answer 15

Between the ribs and the costal cartilage (cartilaginous joint – synchondrosis)

Question 16

Sternocostal joints

Answer 16

o Between the ribs and the sternum
o Ribs 1 synchondrosis and 2-7 synovial

Question 17

interchondral joints

Answer 17

o Between costal cartilage and the false ribs
o Synovial, reinforced with ligaments

Question 18

Sternal symphyses

Answer 18

o Manubriosternal
o Xiphisternal

Question 19

Understand the borders of the inferior thoracic apertures and structures passing through each

Answer 19

 Large, expandable, consist of bone, cartilage and ligaments
 Lines and sealed by diaphragm

Question 19

Understand the borders of the superior thoracic apertures and structures passing through each

Answer 19

 Rib 1, costal cartilage, manubrium, T1
 Orientated obliquely

Question 20

Describe the features of the diaphragm

Answer 20

o Double domes shape
o Muscle fibres radiate from the margins f the outlet to a central tendon
o Openings for structures passing between thorax and abdomen

Question 21

Describe the attachments of the diaphragm

Answer 21

o Muscular fibres converge centrally
o Attaches at xiphoid process, inferior 6 costal cartilages and ribs, to lumbar vertebrae via median and lateral arcuate ligaments

Question 22

Describe the apertures of the diaphragm

Answer 22

o Caval opening for inferior vena cava
o Oesophageal hiatus of oesophagus
o Aortic hiatus for aorta (not an opening through diaphragm, instead a gap at posterior edge)

Question 23

Describe the innovation of the diaphragm

Answer 23

o Innervated by two phrenic nerves
o Arise from anterior rami of C3-5
o C3, 4, 5 keeps the diaphragm alive!

Question 24

Blood supply of thoracic wall

Answer 24

o Thoracic aorta
o Internal thoracic artery
o Intercostal Arteriors (posterior an anterior)

Question 25

Venous drainage of thoracic wall

Answer 25

o Anterior intercostal veins
 Empty into internal thoracic and brachiocephalic
o Posterior intercostal veins
 Empty into azygous venous system

Question 26

Innervation of the thoracic wall

Answer 26

o Diaphragm = phrenic nerve
o Intercostal muscles = intercostal nerves

Question 27

Movements of thoracic wall

Answer 27

o Anteroposterior and lateral changes in the thoracic wall due to rotation of the ribs on the vertebrae
 External intercostals
 Bucket handle-type movement
o Vertical changes in the thoracic wall due to contraction of the diaphragm
o Any mm in the neck or back attaching to the ribs can act as accessory respiratory mm
 Abdominal & neck mm
 Forced breathing

Question 28

What are the muscles of the thoracic wall?

Answer 28

o Muscles filling the spaces between the ribs
 Intercostal spaces
o Muscles passing between the ribs and the sternum
o Muscles spanning multiple ribs