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

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Don’t it is in fooled their long, curved shape! Rib bones are not divide as lengthy bones. Instead, anatomists divide the ribs as level bones, and they are located within the axial skeleton. In addition to the sternum, thoracic vertebrae, and costal cartilages, the ribs type the thoracic cage, additionally called the bony thorax.

Ribs Anatomy

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


True Ribs, False Ribs, and also Floating Ribs

The true ribs include rib bag 1-7, with each rib articulating posteriorly come the thoracic vertebrae and also anteriorly come the sternum via costal cartilages. Because the true ribs affix to both the thoracic vertebrae and the sternum, anatomists sometimes splice those terms together and also call the true ribs “the vertebrosternal ribs.”The false ribs encompass rib bag 8-12. Favor the true ribs, these false ribs articulate v thoracic vertebrae posteriorly. However, they carry out not affix directly to the sternum anteriorly, and instead, connect to the costal cartilage the the preceding (superior) rib, except for false ribs 11-12, which room the floating ribs. Because the false ribs affix to the vertebrae posteriorly and costal cartilage anteriorly, anatomists sometimes contact the false ribs vertebrochondral ribs (vertebro = vertebrae; chondral = cartilage).The floating ribs (11-12) space the last two pairs the false ribs, but unlike the various other false ribs, they do not affix to the cartilage of the coming before ribs on the anterior side. Instead, they affix posteriorly come the thoracic vertebrae and “float” there is no attaching to the costal cartilage anteriorly, therefore anatomists simply contact them “vertebral ribs.”

Intercostal Spaces

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


There room three main varieties of intercostal muscle, i beg your pardon facilitate chest movement: outside intercostal muscles, internal intercostal muscles, and also innermost intercostal muscles.

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

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

As I discussed in mine sternum anatomy video, the 2nd pair the ribs meet at the junction in between the manubrium and also the human body of the sternum, creating the sternal angle (or angle of Louis). The 2nd intercostal room will be just listed below the second pair that ribs. Indigenous there, you have the right to count the intercostal spaces to situate the apical pulse, i m sorry is top top the left next of the chest at the fith intercostal space, under the midclavicular line.

Other intercostal spaces will permit you to assess different chest evaluate sounds.

Rib Bone Anatomy and also Landmarks

When examining individual rib bones, you’ll notification that some have different structures, so anatomists categorize ribs right into two key types: typical and atypical.

Typical Rib Bones

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


The anterior extremity is concave and also porous, permitting for the attachment of the costal cartilage in ~ the prior of the thoracic cage.The pillar (body) of a common rib is flat however long, and it curve sharply close to its posterior end, developing an angle recognized as the costal angle (or edge of the rib). A groove called the costal groove extends down the worse (bottom) part of the rib’s shaft, which permits for the passage of intercostal vessels and nerves. This groove creates a spicy inferior border compared to the smoother superior border, which permits you to determine the proper orientation the the rib bone (sharper side constantly faces down).The tubercle is the tiny bumpy area where the body meets the neck. The articular component of the tubercle articulates through the transverse procedure of the inferior vertebra, and also the non-articular part allows for the attachment of the ligament that the tubercle.The neck associate the body (shaft) the the rib come the head.The head is top top the posterior end, and 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 that articulates with the vertebra that the same rib number (example: rib 3 articulates through thoracic vertebra 3 at the inferior facet and vertebra 2 and also the premium facet). This facets are separated through 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 more comprehensive than all other ribs, and its broad, flat surface has grooves that assistance the subclavian vessels. Because rib 1 articulates with an initial thoracic vertebra only, there is a solitary facet on its head (typical ribs have two facets, as mentioned above). A scalene tubercle allows for the attachment of the scalene muscles.Rib 2 is also quite curved, but it is longer than rib one and also not as flat. The serratus anterior muscle originates from a roughened area near the middle of this rib, and it articulates v thoracic vertebrae 1 and 2 (T1 and also T2).Rib 10 has actually only a single articular facet on that is head.Ribs 11 and also 12 also have a solitary articular facet on the head, however no necks or tubercles.

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Free Quiz and an ext Anatomy Videos

Take a free ribs anatomy quiz come test her knowledge, or review our ribs anatomy video. In addition, you can want to clock our anatomy and physiology lectures ~ above YouTube, or examine our anatomy and also physiology notes.