Part 2: Thoracic Wall + Diaphragm

Question 1

What are the joints of the rib?

Answer 1

Joint of head of ribs
Joints at the tubercles (costotransverse joints)
Costochondral
Sternocostal

Question 2

Describe the joints of the head of the ribs

Answer 2

Rib articulates with body of vertebrae. By way of 2 joints - lower articulates to vertebrae of rib and upper to the vertebrae above. Ridge between articulates with IV disc. 3 pronged radiate ligament to each vertebrae and IV disc lies anteriorly for reinforcement. Exceptions are T1, T11 +T12 which only articulate with their own vertebrae

Question 3

Describe the joints at the tubercles

Answer 3

Rib tubercles articulate with transverse process. Medial facet articulates with tip of transverse process with small synovial joint.
Lateral facet is non-articular and gives attachment to lateral costotransverse ligament

Question 4

Describe the 3 costotranverse ligaments

Answer 4

Costotranverse ligament - back of neck of rib to front of transverse process
Lateral costotransverse - lateral facet to transverse process
Superior costotransverse - crest of rib to under surface of transverse process of above veterbrae

Question 5

Describe the costochondral joints

Answer 5

Each rib makes a primary cartilaginous joint with costal cartilage. No movement takes place at these joints.

Question 6

Describe the interchondral joints

Answer 6

Costal cartilages 6+7, 7+8, 8+9 are joined to adjacent surfaces by small synovial joints

Question 7

Describe the sternocostal joints

Answer 7

Should be called sternochondral joints. Rib 1 articulates with manubrium with a primary cartilaginous joint giving fixation necessary for stability of clavicle and pectoral girdle. Next 6 costal cartilages articulate with sternum via synovial joints

Question 8

Describe the manubriosternal joint

Answer 8

Contains hyaline surfaces with intervening disc of fibrocartilage making it a secondary cartilaginous joint

Question 9

Describe the xiphisternal joint

Answer 9

Fibrocartilaginous disc between cartilage covered surfaces

Question 10

Serratus posterior superior is part of the outer muscles of thoracic wall, where does it pass? What is its action?

Answer 10

From C6, 7, T1, 2 to ribs 2-5 covered by levator scapulae and rhomboids
Elevates upper ribs in inspiration

Question 11

Serratus posterior inferior is part of the outer muscles of thoracic wall, where does it pass? What is its action?

Answer 11

T11, 12, L1, 2 and lumbar fascia to ribs 9-12

Depresses lower ribs in expirations

Question 12

Levator costae is part of the outer muscles of thoracic wall, where does it pass? What is its action?

Answer 12

12 pairs spreadin from near tip of transverse process of C7-T11 to insertion in upper border same rib.
Presumably aids in elevation of ribs. Only thoracic muscle to be supplied by posterior rami as originated with back muscles

Question 13

External intercostals are part of the outer muscles of thoracic wall, where does it pass?

Answer 13

Pass obliquely downwards from sharp border of rib above to rounded border of rib below. Extend from costotransverse ligament to costochondral junction blending into anterior intercostals membrane.

Question 14

Internal intercostals are part of the middle muscles of thoracic wall, where does it pass?

Answer 14

Downwards and backwards from costal groove to upper border. Extends from posterior intercostal membrane as far as side of sternum

Question 15

What are the muscles of the inner layer of thoracic wall and how are they positioned?

Answer 15

Subcostal muscles - posterior - cross more than 1 vertebral space
Innermost intercostals - Lateral - cross more than 1 space
Transverse thoracis - Anterior - digitations each side of sternum

Question 16

Where does the NVP lie in the thoracic wall?

Answer 16

Runs between middle and inner layer. Protected under the lip of superior rib

Question 17

What nerves supply thoracic muscles?

Answer 17

Anterior rami of spinal nerves supply all muscles but levator costae (posterior rami)

Question 18

Describe the course of the intercostal nerves

Answer 18

Continuation of spinal nerve once posterior rami has branched off. Runs between middle and inner layer of muscles. Main nerve has lateral cutaneous branch and a terminal anterior cutaneous branch
Lower 5 intercostals slope downwards and supply anterior abdominal wall.
1st nerve is small and supplies no skin.

Question 19

What is the blood supply of the thoracic wall?

Answer 19

Intercostal arteries arise at back and front
Posterior - super intercostal artery supplies upper 2 spaces (comes off subclavian trunk)
Spaces 3-11 are supplied by thoracic aortic branches
Anterior - Upper 6 from internal thoracic, then musculophrenic in 7-9 spaces

Question 20

What is the venous drainage of the thoracic wall?

Answer 20

Intercostal veins drain both posteriorly and anteriorly.
1st space - drains to vertebral/brachiocephalic vein
2-3 - superior intercostal vein -> R to azygous and L to brachiocephalic
Lower 8 - azygous on R, hemiazygous on L

Question 21

Where does the internal thoracic artery arise and where does it go?

Answer 21

1st part subclavian passes vertically down lateral to sternum. Divides into superior epigastric and musculophrenic at costal margin

Question 22

What is the suprapleural membrane?

Answer 22

Dense layer of tissue attached to inner border of 1st rib and costal cartilage and posteriorly to transverse process of C7 where muscles fibres found (scalenus minimus). Gives rigidity to thoracic inlet to prevent gross distortion during respiration

Question 23

Which layer is the diaphragm derived from?

Answer 23

Innermost layer

Question 24

How is the diaphragm anchored to vertebrae?

Answer 24

Crura anchor to vertebrae

R: L1-3, L: L1-2

Question 25

What are the arcuate ligaments?

Answer 25

Median arcuate - between both crus, binds aorta
Medial arcuate - Thickening psoas fascia from body L1 to ridge on transverse process of L1
Lateral arcuate - Ridge transverse process L1 to 12th rib lateral border quadratus lumborum
Lateral and medial give rise to muscle fibres

Question 26

What is the shape of the central tendon?

Answer 26

Club or 3 leaf clover with a leaf towards each paravertebral gutter

Question 27

What are the main diapragmatic openings and what levels are they

Answer 27

T12 - aorta, azygous and thoracic duct (behind median arcuate ligament)
T10 - Oesphagus, vagal trunks, esphageal branches of left gastric vessels (L of midline, fibres of L + R crus form sling
T8 - Vena cava, R phrenic nerve (lies in central tendon)

Question 28

What are other lesser openings of diaphragm?

Answer 28

Hemiazygous vein - L crus
Splanchnic nerves - each crus
Subcostal nerve - behind lateral arcuate ligament
L phrenic pierces the dome
Superior epigastric vessels

Question 29

What are the types of acquired hernias?

Answer 29

Sliding - phreno-oesphageal ligament becomes stretched (commonest)
Gliding - pouch of peritoneum projects upwards alongside oesphagous

Question 30

What is the blood supply to the diaphragm?

Answer 30

R + L inferior phrenic arteries. Intercostal and subcostals supply the costal margin

Question 31

What is the nerve supply of the diaphragm?

Answer 31

Phrenic nerve to each side (C3,4,5) mainly C4.

Question 32

What are the mechanical respiratory movements?

Answer 32

Pump handle - upper ribs move anterior and up (increases anteroposterior dimensions as manubrium is lifted up)
Bucket handles - lower libs elevate up and lateral - increases transverse diameter
Diaphragm moves down increasing vertical diameter

Question 33

What are the muscles of inspiration?

Answer 33

Diaphragm, intercostal muscles, scalene muscles, SCM and EICM are accessory

Question 34

What are the muscles of expiration?

Answer 34

Largely passive

Assisted by abdominal muscles