Short method for those student who's never under stand the ribs topics

1. ANATOMY OF THE RIBS
 The ribs are a set of twelve paired bones
which form the protective ‘cage’ of
the thorax. They articulate with the
vertebral column posteriorly, and terminate
anteriorly as cartilage (known as costal
cartilage).
 As part of the bony thorax, the ribs protect
the internal thoracic organs. They also have
a role in ventilation; moving during chest
expansion to enable lung inflation.

2. RIB STRUCTURE
There are two classifications of ribs – atypical and typical. The typical ribs
have a generalized structure, while the atypical ribs have variations on this
structure.
1-TYPICAL RIBS:
The typical rib consists of a head, neck and body:
 The head is wedge shaped, and has two articular facets separated by a
wedge of bone. One facet articulates with the numerically corresponding
vertebra, and the other articulates with the vertebra above.
 The neck contains no bony prominences, but simply connects the head
with the body. Where the neck meets the body there is a roughed tubercle,
with a facet for articulation with the transverse process of the
corresponding vertebra.
 The body, or shaft of the rib is flat and curved. The internal surface of the
shaft has a groove for the neurovascular supply of the thorax, protecting
the vessels and nerves from damage.

4. 2-Atypical Ribs:
Ribs 1, 2, 10 11 and 12 can be described as ‘atypical’ – they have features
that are not common to all the ribs.
 Rib 1 is shorter and wider than the other ribs. It only has one facet on its
head for articulation with its corresponding vertebra. The superior surface
is marked by two grooves, which make way for the subclavian vessels.
 Rib 2 is thinner and longer than rib 1, and has two articular facets on the
head as normal. It has a roughened area on its upper surface, from which
the serratus anterior muscle originates.
 Rib 10 only has one facet – for articulation with its numerically
corresponding vertebra.
 Ribs 11 and 12 have no neck, and only contain one facet, which is for
articulation with their corresponding vertebra.

5. ARTICULATIONS
The majority of the ribs have an anterior and posterior
articulation.
Posterior:
All the twelve ribs articulate posteriorly with
the vertebra of the spine. Each rib forms two joints:
 Costotransverse joint – Between the tubercle of the
rib, and the transverse costal facet of the
corresponding vertebra.
 Costovertebral joint – Between the head of the rib,
superior costal facet of the corresponding vertebra,
and the inferior costal facet of the vertebra above.

6. Anterior:
The anterior attachment of the ribs vary
 Ribs 1-7 attach independently to the
sternum.
 Ribs 8 – 10 attach to the costal cartilages
superior to them.
 Ribs 11 and 12 do not have an anterior
attachment and end in the abdominal
musculature. Because of this, they are
sometimes called ‘floating ribs’.

7. THE MUSCLES OF THE THORACIC CAGE
There are five muscles that make up the thoracic
cage;
• INTERCOSTALS (external, internal and
innermost),
• SUBCOSTALS
• TRANSVERSUS THORACIS
These muscles act to change the volume of the
thoracic cavity during respiration.

8.  INTERCOSTALS
The intercostal muscles lie in the intercostal spaces between ribs. They
are organised into three layers.
1. External Intercostals
There are 11 pairs of external intercostal muscles. They run
inferoanteriorly from the rib above to the rib below, and
are continuous with the external oblique of the abdomen.
Actions: Elevates the ribs, increasing the thoracic volume.

9. 2. Internal Intercostals
These flat muscles lie deep to the external intercostals.
They are continuous with the internal oblique muscle of
the abdominal wall.
Actions: The interosseous part reduces the thoracic
volume by depressing the ribcage, and the interchondral
part elevates the ribs.
3. Innermost Intercostals
These muscles are the deepest of the intercostal
muscles, and are similar in structure to the internal
intercostals.
Actions: The interosseous part reduces the thoracic
volume by depressing the ribcage, and the interchondral
part elevates the ribs.

10.  TRANSVERSUS THORACIS
These muscles of the thoracic cage are continuous with transversus
abdominis inferiorly.
Actions: Weakly depress the ribs.
 SUBCOSTALS
The subcostal muscles are found in the inferior portion of the thoracic
wall.
Actions: Share the action of the internal intercostals

11. LIGAMENTS
 Costotransverse ligaments:
The main ligamentous attachment to the ribs is the costotransverse ligament.
This is a fairly complex ligament which is made up of three parts.
The first part is known as ‘The costotransverse ligament’ and it fills the gap between
the rib and the corresponding transverse process.
 Lateral Costotransverse ligaments:
The next group of fibres are known as the lateral costotransverse ligament, which lies
posteriorly and attaches the transverse process of the vertebra to the rib, just distal to
the tubercle.
 Superior costotransverse ligament:
The final part is the superior costotransverse ligament which is a two-layered ligament
with the fibres orientated at right angles. This passes from the superior margin of the
neck of the rib to the transverse process of the above vertebra.