Thorax

Question 1

Mediastinum

Answer 1

Cavity in the median sagittal position of the thorax.

Contains:
Heart
Oesophagus
Trachea
Major Systemic blood vessels
Phrenic nerves

Question 2

Function of the thorax

Answer 2

Protection:

• Thoracic wall protects vital organs: heart, lungs, great vessels
• Protects some viscera organs

Breathing:

• The pleural cavity contains the lungs and the cavity extends beyond the first rib
• The thoracic wall acts as mechanical support and well as the diaphragm which curves up to the 6th rib.

Conduit:

• Allows a passage for structures to connect from one region to another
• Connects organs in the thorax to other parts of the body

Question 3

Sternum

Answer 3

Composed of :
Manubrium, Main body and Xiphoid process.

Forms a sternal angle that is can be seen in surface anatomy- a bump

Allows attachment of true ribs: 1-7

Question 4

Manubrium

Answer 4

Superior section of the sternum.

Superior surface contains a jugular notch.

Attached to main body through a manubriosternal joint.

Allows attachment for the first rib and the upper end of rib 2 through the demifacet.

Contains oval fossa for the attachment of the clavicle.

Question 5

Main body of the sternum.

Answer 5

Inferior to the manubrium inferior to the xiphoid process.

At the lateral superior border contains demifacet for the attachment of the second rib.

Contains articular facets for the attachments for ribs 3-6.

The lateral inferior border contains a demifacet for rib 7.

The anterior surface contains many transverse ridges

Question 6

Xiphoid process

Answer 6

The inferior sections of the sternum.

The anterior lateral margin contains:
A demifacet for the articulation of the costal cartilage of the inferior end of the 7th rib.

Question 7

Describe a typical rib

Answer 7

Includes ribs 3-9, 10
Contains: Head, neck, angle, costal cartilage and costal groove, tubercle.

Head: Contains two articular surfaces separated by a crest.

Tubercle: Contains non-articular and articular regions. Articular region articulates with the transverse process of the vertebrae.
Non-articular forms attachments to the vertebrae by a ligament.

Costal groove: Section where nerves and blood vessels run.

Costal margin: Anterior end of the rib which articulates with the sternum or other ribs.

Question 8

True rib

Answer 8

Ribs that articulate with the sternum:

Ribs 1-7

Question 9

False rib

Answer 9

RIbs that articulate with other ribs:

Ribs 8-10

Question 10

Floating ribs

Answer 10

Ribs that do not articulate to the sternum or other ribs:

Ribs 11-12

Question 11

Articular facet of ribs

Answer 11

The superior articular facet at the posterior end attaches to the inferior costal facet of the vertebrae above its associated one.

The inferior articular facet attaches to the superior costal facet of its associated vertebrae.

Question 12

Typical thoracic vertebrae

Answer 12

Includes ribs 2, 3-8 and 9 sometimes

Contains:

• Heart shaped vertebral body.
• Lamina which overlaps with the vertebrae below.
• Superior articular process and inferior articular process.
• Costal facet:
  Superior articulates with the inferior end of its own rib.
  Inferior articulates with the superior end of the rib below.
• Transverse process: Allows attachment of tubercle, contains facets for the articulation with the tubercle.

Spinous process: Inferior pointing

Question 13

The atypical thoracic vertebrae

Answer 13

T 1, 10-12 and sometimes 9

1- Contains complete costal facet which allows rib 1 to only attach to T1 and not T2 as well

10- Single costal facet.

11+12- Single costal facet and no costal facet on the transverse process.

Question 14

Costotransverse

Answer 14

Synovial joint between the tubercle and transverse process of a vertebrae.

Question 15

Costochondral

Answer 15

Joint between a rib and costal cartilage between ribs.

Question 16

Sternocostal

Answer 16

Joint between the costal cartilage from the rib and the sternum

Question 17

Costovertebral

Answer 17

Joint between a rib and a vertebrae:

Between the articular facets of the head of the rib and the costal facets of the vertebrae.

Question 18

Costotransverse

Answer 18

Joint between the tubercle of the rib and the transverse process of the vertebrae.

Question 19

Sternoclavicular

Answer 19

Joint between the sternum and clavicle.

Question 20

Inferior thoracic aperture.

Answer 20

Bottom of the thoracic cage:

Border:
- Body of T12, posteriorly

• Xiphoid process, anteriorly
• Rib 12 and distal rib 11, posteriolaterally
• Costal cartilage of ribs 7-10, anteriolaterally

Question 21

Superior thoracic aperture

Answer 21

Superior opening of the thoracic cage.

Borders:
- Body of T1, posteriorly

• Manubrium, anteriorly
• Rib 1 on each side at the medial margin. This is angled anteriorly.

Question 22

Describe some of the paediatric variations in the thoracic wall

Answer 22

• Ribs are more horizontal,
• Xiphoid process may protrude
• More circular cavity which causes less expansion laterally when breathing.

Question 23

Origin and insertion of the pectoralis major

Answer 23

Insertion:
Lateral lip of the intertubercular sulcus of the humerus.

Origins:
Medial half of the clavicle

Anterior surface of the sternum and costal cartilages 1-7

Question 24

Innervation of the pectoralis major

Answer 24

Medial and lateral pectoral nerves.

Question 25

Function of the pectoralis major

Answer 25

Medial rotation of the arms.

Flexion of the humerus at the shoulder.

Adduction.

Question 26

Origin and insertion of the pectoralis minor.

Answer 26

Origin:
Ribs 3-5

Insertion:
Coracoid process of the scapula.

Question 27

Innervation of the pectoralis minor

Answer 27

Medial pectoral nerve

Question 28

Function of the pectoralis minor

Answer 28

Stabilises the scapula

Pulls the tip of the shoulder inferiorly

Question 29

Describe the glands of the breast.

Answer 29

Mammary glands, secretory glands:

Drains into lactiferous ducts and out the lactiferous sinus

Question 30

Bloody supply of the breast

Answer 30

Branches of the internal thoracic artery.

2-4th intercostal arteries supply the anteromedial part of the breast.

Question 31

Innervation of the breast.

Answer 31

• Anterior and lateral cutaneous branches of the second to sixth intercostal nerves.
• The nipple is innervated by the fourth intercostal nerve.

Question 32

Lymphatic vessels of the breast.

Answer 32

25% of lymph drains into the parasternal lymphatic vessel.

75% drains into the axillary region.

Question 33

Innervation and function of the external intercostal muscle

Answer 33

Innervation:

Intercostal nerves originating from T1- T11

Function:
Moves ribs superiorly

Runs in the Inferior/ anterior direction

Question 34

Innervation and function of the internal intercostal muscle

Answer 34

Innervation:

Intercostal nerves arising from T1-T11

Function:
Moves ribs inferiorly, allows forced exhalation

Runs in the inferior/ posterior direction

Question 35

Innervation and function of the innermost intercostal muscle

Answer 35

Innervation:

Intercostal nerves arising from T1-T11

Function:
Moves ribs inferiorly

Runs in the inferior/ posterior direction

Question 36

Blood supply of the intercostal muscles

Answer 36

Arterial:
Anterior and posterior intercostal arteries.

Vein:
Internal thoracic veins

Question 37

Serratus anterior

Answer 37

Most superficial muscle in the thoracic wall.

Sits on the lateral surfaces of ribs 1-9

Question 38

Origin and insertion of the serratus anterior

Answer 38

Origin:

Ribs 1-9

Insertion:

Medial border of the scapula

Question 39

Function of the serratus anterior

Answer 39

Protracts the scapula

Question 40

Innervation of the serratus anterior

Answer 40

Long thoracic nerve:

branched from the brachial plexus

Question 41

Scalene tubercle

Answer 41

Located on the first rib: Separates two grooves.

The anterior groove is where the subclavian vein sits
The posterior groove is where the subclavian artery sits.