Chapter3: Thorax (thoracic cage)

Question 1

Thoracic cage is formed of

Answer 1

Front> sternum
Behind> 12 thoracic vertebrae
Sides> ribs

Question 2

Function of thoracic cage

Answer 2

1. Supports and protects thoracic viscera

2. Protects upper abdominal viscera

Question 3

Thoracic inlet boundaries

Answer 3

Ant> upper border of manubrium sterni (jugular/suprasternal notch)
Post> 1st thoracic vertebra
On side> inner border of first pair of ribs

Question 4

Structures passing through thoracic inlet

Answer 4

Oesophagus
Trachea
Apices of lungs+ pleura

Question 5

Vessels through thoracic inlet

Answer 5

Innominate A
Lt common carotid A 
Lt subclavian A 
Internal mammary arteries 
Sup ICA 
Thoracic duct

Question 6

Nerves through thoracic inlet

Answer 6

Phrenic nerves
Vagi nerves 
Sympathetic chains 
Ventral ramus of T1 
Lt recurrent laryngeal nerve

Question 7

Supra pleura membrane shape

Answer 7

Triangular in shape

Question 8

Apex of supra pleura membrane

Answer 8

Post attached to transverse process of C7

Question 9

Base of supra pleura membrane

Answer 9

Lat attached to the medial border of 1st rib and costal cartilage

Question 10

Function of supra pleura membrane

Answer 10

Protect cervical pleura and apex of lung
Prevents the inward suction of structures at root of the neck during inspiration
Prevents the upward bulging of apex of lung during respiratory efforts

Question 11

Thoracic outlet boundaries

Answer 11

Front> xiphoid process
Side> costal margin
Behind> 12th vertebra

Question 12

Manbrium

Answer 12

2 inches long
4 borders : upper lower 2 lateral
Upper lateral > clavicular notch
* articulate with medial end of clavicle > sternoclavicular joint
Upper border> suprasternal notch
Lower border> manubrosternal angle
Lat border articulate with 1st cc > 1ry cartilaginous joint & upper half of 2nd CC { synovial }

Question 13

Body of sternum

Answer 13

4 inches long (T5-T9)
Post surface > concave + smooth
Ant surface > convex +rough

Question 14

Xiphoid process

Answer 14

Remains cartilage till age of 40

Xiphisternal joint at level of T9

Question 15

Muscle attachments to sternum (Ant surface)

Answer 15

• manubrium > sternomastoid, pectoralis major
• body >pectoralis major
• xiphoid > rectus abdominis

Question 16

Muscle attachments to sternum (post surface)

Answer 16

• manubrium > sternohyoid, sternothyroid
• body > sternocostalis
• xiphoid > sternal origin of diaphragm + tip of the xiphoid > linea alba

Question 17

post relation of the sternum

Answer 17

• manubrium > 1. Remmant of thymus gland + ant border of pleurae and lungs
  2. lt innominate vein ( in front of the aortic arch)
  3. Innominate A, lt common carotid, lt subclavian
• body > sternopericardial ligament + Ant border of pleurae and lungs , remnant of thymus gland
• Xiphoid > liver & falciform ligament

Question 18

structures at level of sternal angle

Answer 18

1. Beginning and end of aortic arch
2. end of ascending aorta
3. beginning of descending aorta
4. bifurcation of trachea and deep cardiac plexus
5. division of pulmonary trunk
6. azygos vein joins the SVC
7. thoracic duct reaches lt side of esophagus
8. ligamentum arteriosum + superficial cardiac plexus

Question 19

sternal puncture

Answer 19

specimen of bone marrow can be taken from sternum by a needle (easy because sternum is subcutaneous and has thin cortical bone)

Question 20

sternum splitting

Answer 20

help in operation on the heart or thymus