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

You are watching: The ribs are attached posteriorly to the

Don’t be fooled your long, bent shape! Rib bones room not share as long bones. Instead, anatomists divide the ribs as flat bones, and they are situated within the axial skeleton. Along with the sternum, thoracic vertebrae, and also costal cartilages, the ribs form the thoracic cage, likewise called the bony thorax.

Ribs Anatomy

The mean skeleton includes 24 individual ribs, created in 12 pairs, and also they are divided 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, through each rib articulating posteriorly to the thoracic vertebrae and anteriorly to the sternum via costal cartilages. Since the true ribs connect to both the thoracic vertebrae and the sternum, anatomists periodically splice those state together and also call the true ribs “the vertebrosternal ribs.”The false ribs incorporate rib pairs 8-12. Favor the true ribs, these false ribs articulate with thoracic vertebrae posteriorly. However, they perform not attach directly to the sternum anteriorly, and also instead, attach to the costal cartilage the the coming before (superior) rib, except for false ribs 11-12, which space the floating ribs. Because the false ribs affix 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, yet unlike the other false ribs, they carry out not connect to the cartilage the the coming before ribs ~ above the anterior side. Instead, they attach posteriorly come the thoracic vertebrae and “float” without attaching come the costal cartilage anteriorly, therefore anatomists simply contact them “vertebral ribs.”

Intercostal Spaces

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


There are three main types of intercostal muscle, which facilitate chest movement: external intercostal muscles, interior intercostal muscles, and innermost intercostal muscles.

Each intercostal space is numbered after ~ the rib directly over it. So the very first intercostal an are will be the an are just listed below the first rib; the 2nd intercostal an are is the space below the 2nd rib, and also so on.

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

As I stated in mine sternum anatomy video, the 2nd pair that ribs meet at the junction between the manubrium and the human body of the sternum, creating the sternal angle (or edge of Louis). The 2nd intercostal an are will be just listed below the 2nd pair of ribs. Native there, you have the right to count the intercostal spaces to find the apical pulse, i m sorry is ~ above the left next of the chest at the fith intercostal space, down the midclavicular line.

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

Rib Bone Anatomy and Landmarks

When evaluating individual rib bones, you’ll notice that part have different structures, for this reason anatomists categorize ribs right into two key types: typical and atypical.

Typical Rib Bones

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


The anterior extremity is concave and porous, permitting for the attachment of the costal cartilage at the former of the thoracic cage.The pillar (body) that a usual rib is flat however long, and also it curve sharply near its posterior end, creating an angle recognized as the costal angle (or angle of the rib). A groove referred to as the costal groove extends down the inferior (bottom) part of the rib’s shaft, which allows for the i of intercostal vessels and also nerves. This groove creates a spicy inferior border contrasted to the smoother superior border, which allows you to determine the suitable orientation the the rib bone (sharper side always faces down).The tubercle is the little bumpy area whereby the body meets the neck. The articular part of the tubercle articulates with the transverse process of the inferior vertebra, and the non-articular portion allows for the attachments of the ligament of the tubercle.The neck associate the human body (shaft) that the rib to the head.The head is ~ above the posterior end, and it articulates with vertebrae via 2 facets: a smaller upper facet, i beg your pardon articulates through the vertebra above, and also a bigger facet that articulates through the vertebra that the very same rib number (example: rib 3 articulates through thoracic vertebra 3 in ~ the worse facet and also vertebra 2 and the superior facet). This facets space separated by a bony crest, to which the intra-articular (or interarticular) ligament attaches.

Atyipcal Rib Bones

The atypical ribs encompass ribs 1, 2, 10, 11, and 12.


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

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Free Quiz and much more Anatomy Videos

Take a cost-free ribs anatomy quiz come test your knowledge, or review our ribs anatomy video. In addition, you can want to watch our anatomy and also physiology lectures on YouTube, or check our anatomy and physiology notes.