Ribs & Rib cage

Ribs & Rib cage: Anatomy & FunctionKey facts about the anatomy of the ribs
~ 4 min

The thorax consists of the ribs, the sternum, and thoracic vertebrae.

Thorax
Thorax

There are 12 pairs of ribs (costae) in the human body, which are divided into several types:

  • True ribs I-VII (costae verae). Each is connected to the sternum by a separate cartilage.

True ribs I-VII (costae verae)
True ribs I-VII (costae verae)
  • False ribs VIII-X (costae spuriae), the cartilages of these ribs fuse with each other and with the cartilages of the upper ribs. Consequently, a costal arch (arcus costalis) is formed.

    False ribs VIII-X (costae spuriae)
    False ribs VIII-X (costae spuriae)
  • Floating ribs XI-XII (costae fluctuantes), the anterior edges of these ribs are not attached to the sternum, and simply lie in the muscle thickness.

Floating ribs XI-XII (costae fluctuantes)
Floating ribs XI-XII (costae fluctuantes)

Sometimes the last two ribs are also referred to as false ribs, and the term “floating” is used as a subdivision. Hoever, this is not of high importance.

Let us look at the typical rib structure (some ribs have their own features, which will be described later).

A rib has two parts — a bony part and a cotal cartilage (cartilago costalis);

The bony part and a cotal cartilage (cartilago costalis)
The bony part and a cotal cartilage (cartilago costalis)

two surfaces — an internal (facies interna) and external surface (facies externa);

The internal surface (facies interna)
The internal surface (facies interna)
The external surface (facies externa)
The external surface (facies externa)

and two borders — the superior border (margo superior) and the inferior border (margo inferior).

The superior border (margo superior)
The superior border (margo superior)
The inferior border (margo inferior)
The inferior border (margo inferior)

The bony part consists of the head (caput costae), the neck (collum costae) and the body (corpus costae).

The head (caput costae)
The head (caput costae)
The neck (collum costae)
The neck (collum costae)
The body (corpus costae)
The body (corpus costae)

On the head is the articular surface of the rib head (facies articularis capitis costae), which is used for articulation with the costal facets on the bodies of the respective vertebrae.

The articular surface of the rib head (facies articularis capitis costae)
The articular surface of the rib head (facies articularis capitis costae)

The heads of all ribs except I, X, XI, and XII have a crest of the rib head (crista capitis costae) that is wedged between the demi-facets of the overlying and underlying vertebrae. Because these ribs are connected to the larger facet on the vertebrae separately, they do not have a crest.

The crest of the rib head (crista capitis costae)
The crest of the rib head (crista capitis costae)

The neck of the ten upper ribs also has a ridge (crista colli costae), which serves as an attachment point for the costotransverse ligament.

The ridge (crista colli costae)
The ridge (crista colli costae)

The main formation on the rib body is the tubercle (tuberculum costae).

It is present on the ten upper ribs and contains an articular facet (facies articularis tuberculi costae) for articulation with the costal facet of the transverse process of the corresponding thoracic vertebra.

The tubercle (tuberculum costae)
The articular facet (facies articularis tuberculi costae)
The tubercle (tuberculum costae)

The costal surface curves slightly in front of the tubercle to form the angle of the rib (angulus costae).

The angle of the rib (angulus costae)
The angle of the rib (angulus costae)

On the internal surface of the ten upper ribs, at their INFERIOR border, there is a costal groove (sulcus costae) in which the intercostal artery, vein, and nerve pass.

The costal groove (sulcus costae)
The costal groove (sulcus costae)

Let us examine some characteristics of the first rib (costa prima).

The first rib (costa prima)
The first rib (costa prima)

In contrast to the others, it has other orientations because it has a more horizontal position. These are two facets — the superior facet (facies superior) and the inferior facet (facies inferior), and two borders — the medial border (margo medialis) and the lateral border (margo lateralis).

Moreover, the angle of the first rib matches its tubercle.

The medial border (margo medialis)
The medial border (margo medialis)
The lateral border (margo lateralis)
The lateral border (margo lateralis)

On the superior facet, the scalene tubercle (tuberculum musculi scaleni anterioris) can be distinguished.

The scalene tubercle (tuberculum musculi scaleni anterioris)
The scalene tubercle (tuberculum musculi scaleni anterioris)

Behind this tubercle lies the groove for the subclavian artery (sulcus arteriae subclaviae) and in front lies the groove for the subclavian vein (sulcus venae subclaviae).

The subclavian artery (sulcus arteriae subclaviae)
The subclavian artery (sulcus arteriae subclaviae)

It is also to be repeated that the first rib has no crest on the head.

The groove for the subclavian vein (sulcus venae subclaviae).
The groove for the subclavian vein (sulcus venae subclaviae).

Let us consider the specificity of the second rib (costa secunda).

On the external surface of this rib lies the tuberosity for the serratus anterior (tuberositas musculi serrati anterioris).

The serratus anterior (tuberositas musculi serrati anterioris)
The serratus anterior (tuberositas musculi serrati anterioris)
Dictionary

Ribs & Rib cage

ribs
costae
true ribs
costae verae
false ribs
costae spuriae
costal arch
arcus costalis
floating ribs
costae fluctuantes
costal cartilage
cartilago costalis
internal surface
facies interna
external surface
facies externa
superior border
margo superior
inferior border
margo inferior
head of rib
caput costae
neck of rib
collum costae
body of rib
corpus costae
articular facet of head of rib
facies articularis capitis costae
crest of head of rib
crista capitis costae
crest of neck of rib
crista colli costae
rib tubercle
tuberculum costae
articular facet of rib tubercle
facies articularis tuberculi costae
costal angle
angulus costae
costal groove
sulcus costae
first rib
costa prima
superior facet
facies superior
inferior facet
facies inferior
medial border
margo medialis
lateral border
margo lateralis
scalene tubercle
tuberculum musculi scaleni anterioris
groove for subclavian artery
sulcus arteriae subclaviae
groove for subclavian vein
sulcus venae subclaviae
second rib
costa secunda
tuberosity for serratus anterior
tuberositas musculi serrati anterioris
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