L3. Thoracic wall anatomy

Question 1

Describe the boundaries, bony and muscular components and general contents of throracic cage

Answer 1

Bordered by T1-12 vertebral bodies, Ribs 1-12, manubrium, sternum and xiphoid process.
Containing organs, major vessels and Somatic and ANS nerves.
Sup Thoracic aperture : T1 body, rib 1 and manubrium.

Question 2

What are the 3 parts of the sternum and what do they articulate with

Answer 2

Manubrium: with clavicle, rib 1 and 2,mesosternum
Mesosternum: other 2 parts and cartilage of ribs 2-7
Xiphisternum; nothing

Question 3

What are the structures at the angle of louis- T4/5- transthoracic plane

Answer 3

Rib 2, Arch of aorta, bifurcation of pulmonary trunk, tracheal bifurcation, ligamentum arteriosum, azygos+ SVC.
Used for JVP measuring and counting ribs

Question 4

Which are the true, false and floating ribs. Which are typical and atypical

Answer 4

Typical ribs are 3-9
Atypical ribs are 1-2, 10-12. (top and bottom)
True ribs articulate directly with the sternum (via costal cartilage)= 1-7
False ribs join sternum indirectly/ not at all= 8-12
Floating ribs have no attachment, more mobile protection= 11 & 12

Question 5

Describe the 4 main features of typical ribs

Answer 5

1. Head that articulates with demifacets on body of its own vertebra and the one above + the IV disc via the crest.
2. Tubercle articulates with articular part of transverse process of own vertebra. Non articular part for costotransverse ligament
3. Costal angle= most curved part of the body
4. Costal groove on inferior border protects intercostal neurovascular bundle.

Question 6

What are the features of the first atypical rib

Answer 6

1st rib: Single facet on the head which articulates with T1 only. There is no subcostal groove, but there are grooves on the superior surface for subclavian vessels(vein more anterior) separated by the Scalene tubercle.

Question 7

What are the features of the second atypical rib

Answer 7

2nd rib: There is a rough area on the upper surface: tuberosity for serratus anterior

Question 8

What are the features of the bottom atypical ribs

Answer 8

Ribs 10-12 all only have a single facet on the head to articulate with only their own vertebra
Rib 11 and 12 especially have no neck or tubercle with free end in abdominal musculature. 
#12 doesn't have subcostal groove or angle

Question 9

Most joints are synovial, what are the fibrocartilagenous ones in the intervertebral and sternocostal joints

Answer 9

Intervertebral joints: between vertebral bodies.
Sternocostal: between manubrium and rib 1 and manubriosternal joint.
NB: interchondral joints at the lower ribcage are synovial plane joints.

Question 10

Describe the costovertebral joints and ligaments

Answer 10

At the joint of the ribs with the vertebral body, there are two separate synovial joint cavities for each costal demifacet separated by an intra-articular ligament. Contained in 1 joint capsule.
3 Costotransverse ligaments to support and stabilise joint, one to transverse process of superior, and one posterior and one lateral to tp of own level

Question 11

Describe the movement of ribs during inspiration

Answer 11

Upper ribs have more lateral axis so have more ant and superior movement. Lower ribs have more posterior axis so have lateral and superior bucket handle movement

Question 12

What passes through the inferior aperture

Answer 12

IVC at T8, Oesophagus at T10, Aorta at T12, Vagus CNX to abdominal plexus, Splanchnic nerves and Thoracic duct.

Question 13

What are the 3 intercostal muscles and the neurovascular plane

Answer 13

Out to in: External intercostal (becomes membrane at costal cartilage), Internal intercostal (starts form sternum), innermost intercostal.
Neurovascular plane is between internal and innermost intercostal

Question 14

What is the organisation of nerves in intercostal space, and the order of structures overall in the neurovascular bundle

Answer 14

The intercostal nerve originates from the vertebral level (at the 12=subcostal nerve). The Anterior rami give motor and sensory nerves. There are lateral and anterior perforating (cutaneous) branches.
Order from top to bottom= Vein, Artery, Nerve

Question 15

What is the arterial supply in the intercostal space

Answer 15

Anterior intercostal arteries for 1-6 originate from the internal thoracic artery which runs parasternally between ribcage and transversus thoracis muscle.
The 7-9 is from musculophrenic (alternative branch to sup epigastric)
these meet in the middle with the posterior intercostal arteries.
1 and 2 from Supreme intercostal artery. 3-11 and subcostal from Thoracic aorta.

Question 16

What is the venous drainage in the intercostal space

Answer 16

Anterior intercostal veins: from internal thoracic vein

Posterior intercostal veins drain to azygos vein on right side, accessory hemiazygos and hemiazygos on the left side.

Question 17

What is the structure, and lymphatic drainage of the female breast

Answer 17

Mostly adipose tissue (and glandular) on top of deep pectoral fascia.
75% to axillary nodes, remainder to parasternal nodes which can cross to the opposite side, inferior breast may drain small to abdominal nodes

Question 18

What is the blood supply to the breast

Answer 18

Arterial: Medial mammary branches from the internal thoracic artery and Lateral mammary branches from the lateral thoracic artery.
Venous drainage by the medial and lateral mammary veins

Question 19

What is T4 dermatome landmark

Answer 19

The nipples. Above this more likely to be referred pain from heart/ lungs. Below until umbilicus (t10) epigastric pain with some overlap

Question 20

Whats the difference between kyphosis and lordosis

Answer 20

Kyphosis is hunchback, lordosis is potbelly