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

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Don’t it is in fooled their long, curved shape! Rib bones are not share as long bones. Instead, anatomists classify the ribs as flat bones, and also they are located within the axial skeleton. Together with the sternum, thoracic vertebrae, and costal cartilages, the ribs kind the thoracic cage, additionally called the bony thorax.

Ribs Anatomy

The average skeleton consists of 24 separation, personal, instance ribs, developed in 12 pairs, and also they are split into three main categories: true ribs, false ribs, and floating ribs.


True Ribs, False Ribs, and also Floating Ribs

The true ribs include rib pairs 1-7, with each rib articulating posteriorly to the thoracic vertebrae and also anteriorly come the sternum via costal cartilages. Because the true ribs attach to both the thoracic vertebrae and also the sternum, anatomists periodically splice those terms together and call the true ribs “the vertebrosternal ribs.”The false ribs include rib bag 8-12. Choose the true ribs, these false ribs articulate through thoracic vertebrae posteriorly. However, they execute not attach directly come the sternum anteriorly, and instead, attach to the costal cartilage the the coming before (superior) rib, other than for false ribs 11-12, which room the floating ribs. Since the false ribs connect to the vertebrae posteriorly and also costal cartilage anteriorly, anatomists sometimes contact the false ribs vertebrochondral ribs (vertebro = vertebrae; chondral = cartilage).The floating ribs (11-12) room the last 2 pairs that false ribs, however unlike the other false ribs, they perform not attach to the cartilage that the preceding ribs ~ above the anterior side. Instead, they connect posteriorly to the thoracic vertebrae and “float” without attaching come the costal cartilage anteriorly, so anatomists simply contact them “vertebral ribs.”

Intercostal Spaces

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


There room three main species of intercostal muscle, i m sorry facilitate chest movement: outside intercostal muscles, interior intercostal muscles, and also innermost intercostal muscles.

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

These intercostal spaces are crucial landmarks for nurses and also other health care professionals, especially when assessing lung sounds and heart sounds.

As I stated in my sternum anatomy video, the 2nd pair of ribs accomplish at the junction in between the manubrium and the human body of the sternum, developing the sternal edge (or angle of Louis). The 2nd intercostal room will be just listed below the second pair of ribs. Indigenous there, you deserve to count the intercostal spaces to find the apical pulse, which is on the left side of the chest in ~ the fith intercostal space, down the midclavicular line.

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

Rib Bone Anatomy and Landmarks

When assessing individual rib bones, you’ll notification that part have different structures, therefore anatomists categorize ribs right into two main types: typical and atypical.

Typical Rib Bones

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


The anterior extremity is concave and also porous, enabling for the attachments of the costal cartilage at the prior of the thoracic cage.The tower (body) that a typical rib is flat yet long, and it curves sharply close to its posterior end, forming an angle well-known as the costal angle (or edge of the rib). A groove dubbed the costal groove extends under the worse (bottom) part of the rib’s shaft, which permits for the passage of intercostal vessels and also nerves. This groove create a spicy inferior border compared to the smoother exceptional border, which permits you to recognize the ideal orientation that the rib bone (sharper side constantly faces down).The tubercle is the tiny bumpy area whereby the body meets the neck. The articular component of the tubercle articulates with the transverse process of the worse vertebra, and also the non-articular part allows for the attachments of the ligament that the tubercle.The neck connect the body (shaft) of the rib to the head.The head is top top the posterior end, and also it articulates through vertebrae via 2 facets: a smaller sized upper facet, which articulates with the vertebra above, and a bigger facet that articulates with the vertebra that the exact same rib number (example: rib three articulates v thoracic vertebra 3 in ~ the worse facet and also vertebra 2 and also the superior facet). These facets space separated by a bony crest, come which the intra-articular (or interarticular) ligament attaches.

Atyipcal Rib Bones

The patent ribs incorporate ribs 1, 2, 10, 11, and also 12.


Rib 1 is usually much shorter and wider than all various other ribs, and its broad, flat surface consists of grooves that support the subclavian vessels. Because rib 1 articulates with an initial thoracic vertebra only, there is a single facet top top its head (typical ribs have two facets, as mentioned above). A scalene tubercle permits for the attachment of the scalene muscles.Rib 2 is also quite curved, however it is much longer than rib one and also 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 also T2).Rib 10 has actually only a solitary articular facet on its head.Ribs 11 and 12 likewise have a solitary 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 to test her knowledge, or review our ribs anatomy video. In addition, you can want to watch our anatomy and physiology lectures on YouTube, or inspect our anatomy and also physiology notes.