Thoracic Wall

Question 1

Which is the longest rib?

Answer 1

7th Rib

Length increases from 1-7, then gradually decreases.

Question 2

Which rib has the greatest lateral projection?

Answer 2

8th Rib

Transverse diameter increases from 1-8

Question 3

How are ribs classified according to features?

Answer 3

Typical ribs : 3-9
- have the same general features

Atypical ribs : 1, 2, 10-12
- have differentiating features

Question 4

How are ribs classified according to relation with sternum?

Answer 4

True Ribs : 1-7
- articulate with the sternum anteriorly

False Ribs : 8-12
- do not articulate with the sternum

Question 5

How are ribs classified according to articulation?

Answer 5

Vertebrosternal ribs : 1-7
- articulate anteriorly with sternum

Vertebrochondral ribs : 8-10
- articulate anteriorly with the cartilage of the above rib

Floating ribs : 11-12
- anterior end is free

Question 6

What features are present on anterior end of rib?

Answer 6

A small concave depression

Question 7

What features are present on posterior end of rib?

Answer 7

Head
Neck
Tubercle - on outer surface

Question 8

What are the features of a typical rib head?

Answer 8

(A) a lower articular facet and a smaller (B) upper articular facet, separated by (C) a crest.

Question 9

What does the lower articular facet articulate with?

Answer 9

body of the numerically corresponding vertebrae

Question 10

what does the upper articular facet articulate with?

Answer 10

Next higher vertebrae

Question 11

How is a rib tubercle divided?

Answer 11

(a) medial articular part

(b) lateral non-articular part

Question 12

What is the difference between articular part and non-articular part of rib tubercle?

Answer 12

Articular part
- Bears an oval facet

Non-Articular part

• rough
• pierced by foramina

Question 13

What does the oval facet articulate with?

Answer 13

transverse process of corresponding vertebrae

Question 14

Describe the superior border of a rib shaft.

Answer 14

Is thick and rounded

Has an outer lip to which the external intercostal muscle attaches.

Has a inner lip to which the internal intercostal & intercostalis intimus muscles attach.

Question 15

Describe the lower border of a rib shaft.

Answer 15

Is sharp

Forms lower border of costal groove.

Question 16

Which muscle attaches to lower border of rib shaft?

Answer 16

External intercostal muscles

Question 17

Describe the outer surface of rib shaft.

Answer 17

Smooth and convex

Question 18

Describe the inner surface of rib shaft?

Answer 18

Smooth and concave

Presents costal groove near lower border

Question 19

What sits within the costal groove?

Answer 19

Intercostal VAN

Question 20

What are the distinguishing features of 1st rib head?

Answer 20

• Small
• Rounded
• Bears single circular articular facet

Question 21

What are the distinguishing features of 1st rib shaft?

Answer 21

• Slopes obliquely upwards, backwards and forwards to its sternal end
• No costal groove

Question 22

What are the distinguishing features of 1st rib neck?

Answer 22

• rounded
• elongated
• directed upwards, backwards and laterally.

Question 23

What are the features rib 1s upper surface?

Answer 23

Presents a scalene tubercle about its middle

Two oblique grooves separated by ridge:

(a) anterior groove
(b) posterior groove

Question 24

What attaches to the scalene tubercle?

Answer 24

Scalenus anterior muscle

Question 25

List the muscles attaching to rib I

Answer 25

Scalenus medius - area behind posterior groove

Scalenus anterior - Scalene tubercle

Subclavius - area anterior to anterior groove

Costoclavicular L. - area anterior to anterior groove

Question 26

What lodges within anterior and posterior groove of Rib I?

Answer 26

Anterior - subclavian vein

Posterior - subclavian artery & lower trunk of brachial plexus

Question 27

At what level is the manubrium situated?

Answer 27

T3 - T4