Thorax

Question 1

Describe the surface landmarks of the thorax

Answer 1

Bony
1. Suprasternal notch(jugular notch)- T2
2. Sternal angle(angle of Louis)- 2nd rib
3. Xiphisternal joint- T9
4. Costal margin- L3
5. Subcostal angle
6. Thoracic vertebral spines
• 7th intercostal space- at posterior axillary line( pleural tap)

Soft tissue
1. Nipple- around 4th intercostal space/ T4

Question 2

Describe the sensory innervation of the thoracic wall, pinpointing the various dermatomes.

Answer 2

Above horizontal line drawn at level of sternal angle
• supraclavicular nerves C3 and C 4

Below
• anterior and lateral cutaneous branches of the 2nd-6th intercostal nerves. (T2-T6)

• The area supplied by C4 spinal segments directly meets the area supplied by T2 spinal segment. This is because the nerves derived from C5-T1 spinal segments form brachial plexus to supply upper limb.

Question 3

Outline the skeletal and muscular components of the chest wall

Answer 3

1. Sternum (anterior)
   -manubrium sterni
   - body
   - xiphoid process
2. Vertebral column (posteriorly)
3. Ribs (costae)
   Cl

Question 4

State the boundaries of the thoracic inlet.

Answer 4

Anterior: suprasternal notch(closed by suprapleural membrane)
Posterior: first thoracic vertebra
Sides: first rib

Question 5

Name the contents of the thoracic inlet.

Answer 5

Vessels
• 3 branches of the aortic arch; (right)brachiocephalic artery, (left) CCA and left subclavian) left and right internal thoracic and left and right superior thoracic
• Brachiocephalic veins
• inferior thyroid veins
• R+L 1st posterior intercostal veins
• thoracic duct

Nerves
• l+r vagus nerves
• left recurrent laryngeal
• l+r phrenic nerves
• sympathetic chain
• R+L 1st thoracic nerve (T1)

viscera
• apex of lung and pleura
• esophagus
• trachea

Muscles
- sternothyroid
- sternohyoid
- Longus colli

Others
• lymphatics
• anterior longitudinal ligament

Question 6

State the boundaries of the thoracic outlet.

Answer 6

Anterior- xiphoid process
Posterior- T12 vertebrae
Sides: last 6 costal cartilages & last rib
- closed by abdominal diaphragm

Question 7

State the parts, articulations and vertebral levels of the STERNUM.

Answer 7

Parts
1. Manubrium
2. Body
3. Xiphoid process

Articulations
• costal cartilages from 1-7 by synovial joints except the 1st which articulates with the manubrium by primary cartilaginous joint

Vertebral levels
1. Suprasternal notch- lower border of T2.
2. Manubrium- T3 and T4
3. Sternal angle- lower border of T4.
4. Body- T5-T8
5. Xiphisternal junction- T9

Question 8

State the muscle attachments of the sternum.

Answer 8

Anterior
1. Manubrium - sternomastoid
2. Body- pectoralis major
3. Xiphoid process - rectus abdominis

Posterior
1. Manubrium- sternohyoid and sternothyroid.
2. Body- sternocostalis
3. Xiphoid process- diaphragm

Question 9

List the structures at the level of the sternal angle

Answer 9

1. 2nd costal cartilage
2. Lower border of T4
3. Bifurcation of the Trachea
4. Bifurcation of the pulmonary trunk
5. Azygos vein enters superior vena cava
6. Aortic arch begins
7. Aortic arch ends
8. Ascending aorta ends
9. Descending thoracic aorta begins
10. Thoracic duct crosses to the left side of the esophagus

Question 10

State the types, features and articulations of the ribs.

Answer 10

** According to relations to the vertebral column**
* Typical and atypical *
• Typical- posterior end of each articulates with 2 thoracic vertebra and the IVD between them. (3-9)
• Atypical - head of each articulates with the vertebra of the same number with the exception of the 2nd rib which articulates with 2 vertebrae, T1 and T2. (1,2,10,11,12)
* The 2nd rib is considered non typical because it’s shaft differs from that of typical ribs.*

**According to the relation with the sternum.
2. True and false
• True ribs are articulate with the sternum anteriorly. From 1-7. Called vertebrosternal.
• False ribs articulate with vertebrae posteriorly and anteriorly with each other. Called vertebrochondral (8,9,10)
• floating ribs end freely in abdominal muscles (11,12)

Features
Typical ribs:(3-9)
1. Posterior end- has head (superior facet, ridge and inferior facet), neck and tubercle( articular and non articular
2. Shaft- has costal groove( contains intercostal vessels and nerves;VAN)
3. Anterior end- articulates with costal cartilage by primary cartilaginous joint

Atypical ribs
First rib
• shortest and broadest
• has scalene tubercle for attachment of scalenus anterior
• groove before scalene tubercle - for subclavian artery
• groove after scalene tubercle- subclavian vein
• neck- related to sympathetic chain, superior intercostal artery, 1st posterior intercostal vein, 1st thoracic nerve T1. ( They are anterior, from medial to lateral)

Articulations of typical ribs
Posterior articulation: e.g. rib 5
• upper facet articulates with T4, ridge with IVD and lower facet with T5.
• the tubercle articulates with the transverse process of T5
Anterior articulation:
• with costal cartilage by primary cartilaginous joint and costal cartilage articulates with sternum by synovial joint.

Question 11

Clinical relationships

Answer 11

How do you count the ribs?
- From the sternal angle, the rib opposite is second rib.
How do you count intercostal spaces?
- begin from the second rib. Each intercostal spaces lies below its own rib.
* The first rib can not be felt, it is covered by muscles

Question 12

Describe the morphological organisation of the lung.

Answer 12

• Pyramidal in shape with an apex (extends into the root of the neck and is covered by the suprapleural membrane) and base ( Rests on the upper surface of the diaphragm).
• Has 2 surfaces: costal (facing the ribs) and medial (facing the heart)
• Has 3 borders:
1. Anterior: sharp
a. Right- straight
b. Left - has cardiac notch and lingula
2. Posterior- rounded
3. Inferior
• Has fissures:
1. Oblique- in both lungs
2. Horizontal/ transverse - in the right lung opposite the fourth rib.
• Lobes:
1. Right lung- 3 lobes ( upper, middle and lower)
2. Left lung: 2 lobes (upper and lower)

Question 13

State the differences between the right and left lung.

Answer 13

** Right lung**
1. Slightly larger- shorter due to upward bulge of right domebof diaphragm.
2. Straight anterior border
3. Has 2 fissures: oblique & horizontal.
4. Has 3 lobes: upper, middle and lower.
5. Hilum: 2 bronchi (eparterial and hyparterial) and 1 bronchial artery.

Left lung
1. Smaller and narrower because the heart bulges to the left side.
2. Anterior border has cardiac notch and lingula.
3. Has one oblique fissure.
4. Has 2 lobes: upper and lower.
5. Hilum: 1 main bronchus and 2 bronchial arteries

Question 14

Describe the layers and parts of the pleura

Answer 14

Layers **
*Parietal:- outer layer, lines the thoracic wall.
* Visceral: - inner layer, covers the lobes of the lung & extends into the fissures

Parts
1. Cervical- extends into the neck
2. Costal- ribs and costal cartilages
3. Mediastinal- mediastinum
4. Diaphragmatic- above diaphragm

Question 15

State the innervation of the pleura

Answer 15

Parietal pleura- similar to chest wall
• sensitive to pain- supplied by somatic nerves
1. Intercostal nerves: supply costal and peripheral diaphragmatic pleura.
2. Phrenic nerves: mediastinal and central diaphragmatic pleura.

Visceral pleura- similar to lung
• not sensitive to pain- autonomic nerves
1. Anterior and posterior pulmonary plexuses. ( Vagus nerves and sympathetic chain)

Question 16

State the blood supply of the pleura.

Answer 16

Parietal pleura- similar to chest wall
1. Intercostal arteries
2. Internal thoracic artery
3. Musculophrenic artery
4. Superior phrenic artery

Visceral pleura- similar to lung
1. Bronchial arteries

Venous drainage
Parietal - intercostal veins, internal thoracic veins, musculophrenic vein, superior phrenic vein.
Visceral- bronchial veins

Question 17

State the clinical relevance of the pleura

Answer 17

1. Pleural effusion - collection of fluid in the pleural cavity, mostly in the costodiaphragmatic recess

Question 18

Describe the lymphatic drainage of the pleura.

Answer 18

Parietal pleura
1. Cervical and costal- intercostal and internal thoracic lymph nodes.
2. Mediastinal - posterior mediastinal LN
3. Diaphragmatic-phrenic lymph nodes.

• Visceral pleura:**
  1. Bronchopulmonary (hilar) lymph nodes;
  2. Tracheobronchial LN;
  3. Bronchomediastinal lymph trunk;
  4. Left bronchomediastinal trunk; thoracic duct.
  5. Right bronchomediastinal trunk; right lymphatic duct.
• ; means drains into*

Question 19

State the origin, course, distribution and clinical relevance of the phrenic nerve.

Question 20

Name and identify the primary and secondary muscles of respiration

Answer 20

Primary:
1. Inspiration- diaphragm and external intercostal muscles
2. Expiration- diaphragm

** Secondary**
1. Inspiration- sternocleidomastoid and scalini
2. Expiration- external and internal intercostals, external and internal obliques, transverse abdominal and rectus abdominis.

Question 21

Explain the mechanisms of inspiration

Answer 21

Increase in vertical diameter
- descent/ contraction of the diaphragm.

Anterosuperior
- pump handle movement of the sternum ( brought about by the elevation of vertebrosternal ribs)

** Transverse**
Bucket handle movement of the vertebrosternal ribs and floating ribs.

Question 22

What is pleura?

Answer 22

• serous membrane that surrounds the lung.
• It has two layers; parietal and visceral.
• there’s a cavity between the 2 layers containing clear serous fluid

Question 23

Discuss the pleural recesses

Answer 23

**Definition:*
• Part of pleural cavity not filled with the lung.
Function:
• allow expansion of lung during forced inspiration.

Sites/types:
1. Costomediastinal recess- along the anterior border of the pleura. Deeper on the left.
2. Costodiaphragmatic recess- along inferior border(base) of the pleura. Largest.o

Question 24

Discuss the root of the lung

Answer 24

Definition:- formed by structures which enter or leave the lung.
Vertebral level: T5-T7
Contents:
1. Bronchus- the left divides after entering the lung, the right divides before entering the lung into eparterial and hyparterial bronchus.
2. Pulmonary artery
3. Superior and inferior pulmonary veins.
4. Bronchial arteries- left lung (2) and right lung (1)
5. Bronchopulmonary lymph nodes.
6. Anterior and posterior pulmonary plexuses: vagus and sympathetic fibers.

Arrangement of structures:

Question 25

Discuss the mediastinal surface of the left lung.( Impressions)

Answer 25

Above the root
1. Aortic arch.
2. (From medial to lateral):
- left CCA
- left phrenic
- left vagus
- left subclavian artery
- trachea
- left recurrent laryngeal
- oesophagus
- thoracic duct
* No impression for the nerves and duct*
In front of the root:
Cardiac impression

Behind the root:
-Descending aorta
-Esophagus

Question 26

Discuss the mediastinal surface of the right lung
* In relation with veins *

Answer 26

Grooves for:
1. Arch of azygos vein
2. Right brachiocephalic vein
3. Superior vena cava
4. Trachea
5. Esophagus
6. Cardiac impression( right atrium) and right phrenic nerve
7. Ascending aorta and thymus gland
8. Azygos vein
9. Inferior vena cava

Question 27

Describe the blood supply of the lungs

Answer 27

Arterial
Right lung- 1 bronchial artery form right 3rd posterior intercostal artery or upper left bronchial artery.
Left lung - 2 arteries form the descending thoracic aorta.

Venous
Right- end in azygos vein
Left - end in superior hemiazygos vein.

Question 28

Discuss the lymph drainage of the lung.

Answer 28

Pulmonary lymph nodes;
Bronchopulmonary (hilar) LN;
Tracheobronchial LN ( bifurcation);
Left Bronchomediastinal lymph trunk; thoracic duct.
Right bronchomediastinal lymph trunk; right lymphatic duct

Question 29

Discuss the surface anatomy of the lung and pleura.

Answer 29

Apex:
Extends into the root of the neck 1 inch above the medial third of the clavicle.
Base:- rib level in the midclavicular line, midaxillary line and paravertebral line.
Lung- 6,8,10
Pleura- 8,10,12
(Respectively)

Question 30

Describe the classification of intercostal nerves

Answer 30

2 special nerves
• The 1st nerve- most if it’s fibres ascend to join brachial plexus.
• The last (subcostal) nerve- runs all it’s course in the abdominal wall.

**5 typical **
• From the 2nd to 6th nerves- run all their course in the thoracic wall.

** 5 Nontypical**
• From the 7th to 11th nerves- run part of their course in the thoracic wall & part in the abdominal wall.

Question 31

State the branches of a typical intercostal nerve.

Answer 31

1. Ganglionic branches
- Each nerve gives a white ramus commuicans (preganglionic) and receives a grey ramus communicants (postganglionic) from the corresponding ganglion of the sympathetic chain.

2. Collateral branch (motor)
- Runs along the upper border of the rib below and supplies the intercostal muscles.

3. Lateral cutaneous branch
- Passes laterally in the mid axillary line by piercing the muscles of the intercostal space & serratus anterior to reach the skin where it divides into anterior and posterior branches that supply the side of the chest.

4. Anterior cutaneous branch
- Termination of intercostal nerve. Divides into medial and lateral branches to supply front of the chest.

5. Muscular branch
- From main nerve and it’s collateral branch to supply the intercostal muscles.

6. Pleural & peritoneal branch
- To parietal layeri of the serous membranes.

7. Articular branch
- Joints of the ribs

• Imtercostobrachial nerve is the lateral cutaneous branch of the 2nd intercostal nerve, which unlike the others, does not divide into anterior and posterior branches but it passes laterally to supply the skin of the floor of axilla.**

Question 32

State the characteristics of thoracic vertebra

Answer 32

Characteristics of thoracic vertebra:
- body is heart shaped and has superior and inferior demifacets for articulation with heads of ribs.
- vertebral foramen- narrow and circular.
- transverse process- directed posterolaterally and has an articular surface near the tip to articulate with numerically corresponding rib.
- superior and inferior articular processes are nearly vertical- articulates with 2 vertebra; one above and one below.
- spinous process is long and directed downwards and backwards.

Question 33

Discuss the atypical intercostal nerves

Answer 33

1. First intercostal nerve
- the greater part joins the ventral ramus C8 spinal nerve to form lower trunk of brachial plexus. The remaining nerve is small and lacks both anterior and lateral cutaneous branches.

2. Second intercostal nerve
- lateral cutaneous nerve is called intercostobrachial. It joins the medial cutaneous branch of the arm.
Intercostobrachial supplies the skin of the floor of the axilla and upper part of medial side of the arm.

3. Seventh to eleventh intercostal nerves
- these leave the corresponding intercostal spaces to enter the abdominal wall thus called thoracoabdominal nerves. These nerves supply muscles of the corresponding intercostal spaces, muscles of anterior abdominal wall and the skin and parietal peritoneum covering the inner surfaces of the abdominal wall, respectively