In this anatomy lesson, i’m going to cover the rib bones, additionally called costae in Latin. The ribs help protect an important organs in the thorax such as the heart and lungs, and they aid with breathing.

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Don’t it is in fooled your long, curved shape! Rib bones room not divide as lengthy bones. Instead, anatomists share the ribs as flat bones, and also they are situated within the axial skeleton. In addition to the sternum, thoracic vertebrae, and costal cartilages, the ribs form the thoracic cage, additionally called the bony thorax.

Ribs Anatomy

The average skeleton includes 24 individual ribs, created in 12 pairs, and also they are separated into three key categories: true ribs, false ribs, and floating ribs.


True Ribs, False Ribs, and Floating Ribs

The true ribs include rib pairs 1-7, with each rib articulating posteriorly come the thoracic vertebrae and also anteriorly come the sternum via costal cartilages. Since the true ribs connect to both the thoracic vertebrae and also the sternum, anatomists occasionally splice those state together and also call the true ribs “the vertebrosternal ribs.”The false ribs incorporate rib pairs 8-12. Prefer the true ribs, this false ribs articulate v thoracic vertebrae posteriorly. However, they perform not connect directly come the sternum anteriorly, and also instead, affix to the costal cartilage of the preceding (superior) rib, other than for false ribs 11-12, which room the floating ribs. Due to the fact that the false ribs affix to the vertebrae posteriorly and also costal cartilage anteriorly, anatomists sometimes call the false ribs vertebrochondral ribs (vertebro = vertebrae; chondral = cartilage).The floating ribs (11-12) are the last 2 pairs that false ribs, yet unlike the other false ribs, they perform not affix to the cartilage the the preceding ribs top top the anterior side. Instead, they attach posteriorly to the thoracic vertebrae and “float” there is no attaching come the costal cartilage anteriorly, therefore anatomists simply speak to them “vertebral ribs.”

Intercostal Spaces

The space between each rib is referred to as the intercostal space, and also there room 11 intercostal spaces in the thoracic cage, which are filled with nerves, lymph nodes, arteries, veins, and muscles. In fact, when you eat ribs at a restaurant, you’re eat the intercostal muscles of one animal.


There are three main species of intercostal muscle, i beg your pardon facilitate chest movement: external intercostal muscles, interior intercostal muscles, and innermost intercostal muscles.

Each intercostal room is numbered after the rib directly above it. For this reason the an initial intercostal space will it is in the space just listed below the very first rib; the second intercostal room is the an are below the second rib, and so on.

These intercostal spaces are important landmarks because that nurses and also other medical care professionals, particularly when assessing lung sounds and heart sounds.

As I discussed in my sternum anatomy video, the second pair the ribs accomplish at the junction in between the manubrium and also the human body of the sternum, forming the sternal angle (or edge of Louis). The 2nd intercostal room will it is in just below the 2nd pair the ribs. Indigenous there, you have the right to count the intercostal spaces to find the apical pulse, i beg your pardon is top top the left side of the chest in ~ the fith intercostal space, under the midclavicular line.

Other intercostal spaces will permit you to assess various chest assessment sounds.

Rib Bone Anatomy and Landmarks

When assessing individual rib bones, you’ll notification that some have various structures, so anatomists categorize ribs into two main types: typical and atypical.

Typical Rib Bones

Typical ribs incorporate ribs 3-9, and also they feature a column (or body), head, neck, groove, tubercle, and anterior extremity.


The anterior extremity is concave and also porous, enabling for the attachments of the costal cartilage in ~ the prior of the thoracic cage.The tower (body) of a usual rib is flat but long, and it curve sharply close to its posterior end, creating an angle recognized as the costal angle (or edge of the rib). A groove dubbed the costal groove extends down the inferior (bottom) part of the rib’s shaft, which permits for the passage of intercostal vessels and also nerves. This groove creates a spicy inferior border compared to the smoother superior border, which allows you to identify the ideal orientation the the rib bone (sharper side always faces down).The tubercle is the small bumpy area whereby the body meets the neck. The articular component of the tubercle articulates with the transverse procedure of the worse vertebra, and also the non-articular part allows for the attachments of the ligament that the tubercle.The neck connect the human body (shaft) the the rib to the head.The head is on the posterior end, and also it articulates with vertebrae via 2 facets: a smaller upper facet, i beg your pardon articulates v the vertebra above, and also a larger facet the articulates v the vertebra that the same rib number (example: rib 3 articulates with thoracic vertebra 3 at the inferior facet and also vertebra 2 and the exceptional facet). These facets are separated by a bony crest, to which the intra-articular (or interarticular) ligament attaches.

Atyipcal Rib Bones

The atypical ribs include ribs 1, 2, 10, 11, and also 12.


Rib 1 is usually much shorter and more comprehensive than all other ribs, and also its broad, flat surface includes grooves that support the subclavian vessels. Since rib 1 articulates with an initial thoracic vertebra only, over there is a single facet top top its head (typical ribs have actually two facets, as discussed above). A scalene tubercle allows for the attachments of the scalene muscles.Rib 2 is likewise quite curved, but it is longer than rib one and not together flat. The serratus anterior muscle originates indigenous a roughened area near the middle of this rib, and it articulates through thoracic vertebrae 1 and also 2 (T1 and T2).Rib 10 has actually only a solitary articular side on the head.Ribs 11 and also 12 likewise have a single articular facet on the head, yet no necks or tubercles.

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Free Quiz and an ext Anatomy Videos

Take a cost-free ribs anatomy quiz come test your knowledge, or evaluation our ribs anatomy video. In addition, you might want to watch our anatomy and physiology lectures ~ above YouTube, or examine our anatomy and physiology notes.