Osteology of the thorax - Ribs (dave's notes)

Question 1

Which are the typical ribs? What angle to they lie at?

Answer 1

Ribs 2-10, angle down at 45’, the angle is the most posterior part

Question 2

Describe the head of a typical rib

Answer 2

Bevelled with two articular facets

Question 3

Describe the neck of a typical rib

Answer 3

Flattened with the upper border curling up into a thin prominent ridge.

Question 4

Describe the tubercle of a typical rib

Answer 4

Two smooth facets, medial and lateral. The medial is covered with hyaline cartilage and makes a synovial joint with its own vertebrae. The lateral facet receives the lateral costotransverse ligament from the tip of its own transverse process

Question 5

Describe the shaft of a typical rib

Answer 5

The shaft contains a costal groove.

Question 6

What are the atypical ribs?

Answer 6

The 1st, 11th and 12th ribs

Question 7

What is atypical about the 11th rib?

Answer 7

It has a single articular facet

Question 8

What is atypical about the 12th rib?

Answer 8

It varies in length, has a single articular facet but no tubercle, angle or groove.

Question 9

Describe the head of the first rib.

Answer 9

Small, and carries a single facet

Question 10

Describe the neck and relations of the neck of the first rib.

Answer 10

Slopes backwards and upwards (anterior rami of C8 is above, anterior rami of T1 are below).

Question 11

What structures of note are relations of the first rib?

Answer 11

First rib neck :anterior rami of C8 is above, anterior rami of T1 are below
Sympathetic trunk near the head
Supreme intercostal vein
Superior intercostal artery
First thoracic nerve

Question 12

Describe the tubercle of the first rib

Answer 12

The highest and most posterior part (fusion of the tubercle and angle), and has a synovial joint and a lateral ligament.

Question 13

Describe the shaft of the first rib

Answer 13

Has a groove for artery, scalene tubercle and a groove for the subclavian vein

Question 14

What type of joint does the first rib have with the manubrium?

Answer 14

A primary cartilaginous joint

Question 15

When is the cartilage of the ribs laid down?

Answer 15

In the 6th week

Question 16

When does the bony centre of the rib develop? What about the head and neck of the ribs?

Answer 16

Week 8, head and neck remain cartilaginous until weeks 15-25

Question 17

Which costal cartilages tend to calcify?

Answer 17

All cartilages, especially the first, tend to calcify and then ossify.