Editing Rib

{{Short description|Long bone in vertebrates that protects vital respiratory and cardiovascular organs}}
{{About|the part of the skeleton}}
{{Refimprove|date=June 2008}}
{{Infobox anatomy
| Name        = Rib
| Latin       = costae
| Width       = 
| Image       = Costae - collection.jpg
| Caption     = Collection of single ribs in the Faculty of Education of [[Charles University]]
| Image2      = Ribs animation.gif
| Caption2    = Animation of all ribs, including the false ones in humans
}}

In [[vertebrate]] [[anatomy]], '''ribs''' ({{langx|la|costae}}) are the long curved [[bone]]s which form the [[rib cage]], part of the [[axial skeleton]].<ref>{{Citation|last=Gillen|first=Glen|title=Chapter 18 - Trunk Control: Supporting Functional Independence|date=2016-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780323172813000186|work=Stroke Rehabilitation (Fourth Edition)|pages=360–393|editor-last=Gillen|editor-first=Glen|publisher=Mosby|language=en|doi=10.1016/b978-0-323-17281-3.00018-6|isbn=978-0-323-17281-3|access-date=2020-11-03|url-access=subscription}}</ref> In most [[tetrapod]]s, ribs surround the [[thoracic cavity]], enabling the lungs to expand and thus facilitate [[breathing]] by expanding the thoracic cavity. They serve to protect the [[lung]]s, [[heart]], and other [[vital organ]]s of the thorax. In some animals, especially [[snake]]s, ribs may provide support and protection for the entire body.

==Human anatomy==
===Rib details===
Human ribs are [[flat bone]]s that form part of the [[rib cage]] to help protect internal organs. Humans usually have 24 ribs, in 12 pairs.<ref name=":0">{{Citation|last1=Sly|first1=Peter D.|title=Chapter 7 - Applied Clinical Respiratory Physiology|date=2008-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780323040488500116|work=Pediatric Respiratory Medicine (Second Edition)|pages=73–88|editor-last=Taussig|editor-first=Lynn M.|place=Philadelphia|publisher=Mosby|language=en|doi=10.1016/b978-032304048-8.50011-6|isbn=978-0-323-04048-8|access-date=2020-11-03|last2=Collins|first2=Rachel A.|editor2-last=Landau|editor2-first=Louis I.|url-access=subscription}}</ref> 1 in 500 people have an extra rib known as a [[cervical rib]]. People may have a cervical rib on the right, left or both sides.<ref>{{cite journal |last1=Oner |first1=Zulal |last2=Oner |first2=Serkan |last3=Sahin |first3=Necati Emre |last4=Cay |first4=Mahmut |title=Evaluation of congenital rib anomalies with multi-detector computed tomography in the Turkish population |journal=Folia Morphologica |date=26 January 2023 |doi=10.5603/FM.a2023.0006|pmid=36794687 |s2cid=256899032 |doi-access=free }}</ref>  All are attached at the back to the [[thoracic vertebrae]] and are numbered from 1 to 12 according to the vertebrae to which they attach. The first rib is attached to thoracic vertebra 1 (T1). At the front of the body, most of the ribs are joined by [[costal cartilage]] to the [[sternum]]. Ribs connect to vertebrae at the [[costovertebral joints]].<ref>{{cite book |last1=Moore |first1=Keith L. |last2=Dalley |first2=Arthur F. |last3=Agur |first3=Anne M. R. |title=Clinically Oriented Anatomy |date=2018 |publisher=Wolters Kluwer |location=Philadelphia |isbn=9781496347213 |pages=293–297 |edition=8th}}</ref>

The parts of a rib includes the head, neck, body (or ''shaft''), tubercle, and angle. 

The '''head of the rib''' lies next to a vertebra. The ribs connect to the vertebrae with two costovertebral joints, one on the head and one on the neck. The head of the rib has a superior and an inferior articulating region, separated by a crest. These articulate with the [[superior costal facet|superior]] and [[inferior costal facet]]s on the connecting vertebrae.<ref name="Netter">{{cite book |last1=Netter |first1=Frank |title=Atlas of human anatomy |date=2014 |publisher=Saunders |isbn=9781455704187 |pages=183–184 |edition=Sixth}}</ref> The crest gives attachment to the [[intra-articular ligament of head of rib|intra-articulate ligament]] that joins the rib to the vertebra of the same number, at the [[intervertebral disc]]. Another [[ligament]], the [[radiate ligament of head of rib|radiate ligament]] joins the head of the rib to both the body of the upper vertebra and to the body of the lower vertebra. The smaller middle part of the ligament connects to the intervertebral disc. This [[plane joint]] is known as the [[articulation of head of rib|articulation of the head of the rib]].

The other costovertebral joint is that between the tubercle on the neck and the transverse process of the corresponding thoracic vertebra, known as the [[costotransverse joint]]. The [[superior costotransverse ligament]] attaches from the non-articular facet of the tubercle to the transverse process of the vertebra.

The '''neck of the rib''' is a flattened part that extends laterally from the head. The neck is about 3&nbsp;cm long. Its anterior surface is flat and smooth, whilst its posterior is perforated by numerous foramina and its surface rough, to give attachment to the ligament of the neck. Its upper border presents a rough crest (''crista colli costae'') for the attachment of the anterior [[costotransverse ligament]]; its lower border is rounded. 

A '''tubercle of rib''' on the posterior surface of the neck of the rib, has two facets (surfaces) one articulating and one non-articulating. The articular facet, is small and oval and is the lower and more medial of the two, and connects to the [[transverse costal facet]] on the thoracic vertebra of the same rib number.<ref name="Netter" /> The transverse costal facet is on the end of the transverse process of the lower of the two vertebrae to which the head is connected. The non-articular portion is a rough elevation and affords attachment to the ligament of the tubercle. The tubercle is much more prominent in the upper ribs than in the lower ribs.


===Rib cage===
{{Main|Rib cage}}
[[Image:Ribs labeled.png|thumb|left|200px|[[X-ray]] image of human chest, with ribs labelled]]
The first seven sets of ribs, known as "[[true ribs]]", are attached to the [[sternum]] by the [[costal cartilage]]s. The first rib is unique and easier to distinguish than other ribs. It is a short, flat, C-shaped bone, and attaches to the manubrium.<ref>{{Citation|last1=Sly|first1=Peter D.|title=Chapter 7 - Applied Clinical Respiratory Physiology|date=2008-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780323040488500116|work=Pediatric Respiratory Medicine (Second Edition)|pages=73–88|editor-last=Taussig|editor-first=Lynn M.|place=Philadelphia|publisher=Mosby|language=en|doi=10.1016/b978-032304048-8.50011-6|isbn=978-0-323-04048-8|access-date=2020-11-03|last2=Collins|first2=Rachel A.|editor2-last=Landau|editor2-first=Louis I.|url-access=subscription}}</ref> The vertebral attachment can be found just below the [[neck]] at the first thoracic vertebra, and the majority of this bone can be found above the level of the [[clavicle]]. Ribs 2 through 7 then become longer and less curved as they progress downwards.<ref name="Saladin, K. S. 2010">Saladin, K. S. (2010). Anatomy and Physiology: The Unity of Form and Function (5th ed.). New York, NY: McGraw-Hill.</ref> The following five sets are known as "[[false ribs]]", three of these sharing a common cartilaginous connection to the sternum, while the last two (eleventh and twelfth ribs) are termed [[floating rib]]s.<ref name=":0" /> They are attached to the [[vertebrae]] only, and not to the sternum or cartilage coming off of the sternum. 

In general, human ribs increase in length from ribs 1 through 7 and decrease in length again through rib 12.  Along with this change in size, the ribs become progressively oblique (slanted) from ribs 1 through 9, then less slanted through rib 12.<ref name="Saladin, K. S. 2010"/> 

The rib cage is separated from the lower abdomen by the [[thoracic diaphragm]] which controls breathing. When the diaphragm contracts, the thoracic cavity is expanded, reducing intra-thoracic pressure and drawing air into the lungs. This happens through one of two actions (or a mix of the two): when the lower ribs the diaphragm connects to are stabilized by muscles and the central tendon is mobile, when the muscle contracts the central tendon is drawn down, compressing the cavity underneath and expanding the thoracic cavity downward. When the central tendon is stabilized and the lower ribs are mobile, a contraction of the diaphragm elevates the ribs, which works in conjunction with other muscles to expand the thoracic indent upward.

==Development==
Early in [[human embryogenesis|the developing embryo]], [[somite]]s form and soon subdivide into three [[mesoderm]]al components – the [[myotome]], [[Somite|dermatome]], and the [[sclerotome]]. The vertebrae and ribs develop from the sclerotomes.<ref name="Larsen">{{cite book |last1=Larsen |first1=William |title=Human embryology |date=2001 |publisher=Churchill Livingstone |isbn=0443065837 |pages=80–85 |edition=3rd}}</ref>

During the fourth week ([[Human fertilisation|fertilization age]]) ''costal processes'' have formed on the vertebral bodies. These processes are small, lateral protrusions of [[mesenchyme]] that develop in association with the vertebral arches. During the fifth week the costal processes on the thoracic vertebrae become longer to form the ribs. In the sixth week, the costovertebral joints begin to develop and separate the ribs from the vertebrae. The first seven pairs of ribs, the true ribs join at the front to the [[sternum|sternal]] bars. By the [[fetus|fetal]] stage the sternal bars have completely fused.<ref name="Larsen"/>

The ribs begin as cartilage that later [[ossification|ossifies]] – a process called [[endochondral ossification]]. Primary ossification centers are located near the angle of each rib, and ossification continues in the direction away from the head and neck. During [[adolescence]] secondary ossification centers are formed in the tubercles and heads of the ribs.<ref name="Larsen"/>

==Other animals==
[[File:Dog anatomy lateral skeleton view.jpg|thumb|right|Skeleton of a dog showing the location of the ribs]]
[[File:Eptesicus fuscus ribcage.jpg|thumb|right|Rib cage of the [[big brown bat]] (''Eptesicus fuscus'')]]
In [[jawed fish]], there are often two sets of ribs attached to the vertebral column. One set, the '''dorsal ribs''', are found in the dividing septum between the upper and lower parts of the main muscle segments, projecting roughly sideways from the vertebral column. The second set, the '''ventral ribs''' arise from the vertebral column just below the dorsal ribs, and enclose the lower body, often joining at the tips. Not all species possess both types of rib, with the dorsal ribs being most commonly absent. [[Shark]]s, for example, have no ventral ribs, and only very short dorsal ribs. In some [[teleost]]s, there may be additional rib-like bones within the muscle mass.<ref name=VB>{{cite book |author=Romer, Alfred Sherwood|author2=Parsons, Thomas S.|year=1977 |title=The Vertebrate Body |publisher=Holt-Saunders International |location= Philadelphia, PA|pages= 170–173|isbn= 0-03-910284-X}}</ref>

[[Tetrapod]]s, however, only ever have a single set of ribs which are probably [[homology (biology)|homologous]] with the dorsal ribs of fishes. In the earlier [[tetrapodomorph|choanates]], every vertebra bore a pair of ribs, although those on the [[thoracic vertebra]]e are typically the longest. The [[sacral vertebrae|sacral ribs]] were stout and short, since they formed part of the [[pelvis]], connecting the backbone to the [[hip bone]]s.<ref name=VB/>

In most true tetrapods, many of these early ribs have been lost, and in living [[amphibian]]s and [[reptile]]s, there is great variation in rib structure and number. For example, [[turtle]]s have only eight pairs of ribs, which are developed into a bony or cartilaginous [[carapace]] and [[plastron]], while snakes have numerous ribs running along the full length of their trunk. [[Frog]]s typically have no ribs, aside from a sacral pair, which form part of the pelvis.<ref name=VB/>

In birds, ribs are present as distinct bones only on the thoracic region, although small fused ribs are present on the [[cervical vertebra]]e.  The thoracic ribs of birds possess a wide projection to the rear; this '''uncinate process''' is an attachment for the shoulder muscles.<ref name=VB/> 
Usually dogs have 26 ribs.
Mammals usually also only have distinct ribs on the thoracic vertebra, although fixed cervical ribs are also present in [[monotreme]]s. In [[theria]]n mammals, the cervical and lumbar ribs are found only as tiny remnants fused to the vertebrae, where they are referred to as '''transverse processes'''. In general, the structure and number of the true ribs in humans is similar to that in other mammals. Unlike reptiles, [[caudal vertebrae|caudal]] ribs are never found in mammals.<ref name=VB/>

==Ribs as food==
{{Main|Ribs (food)}}
[[Ribs (food)|Ribs as food]] are widely used from many animals. The ribs are the less meaty part of the [[meat chop]] and they are often cooked as part of a slab; five or more is known as a ''rack'', as in a [[rack of lamb]]. [[Short ribs]] are ribs of beef either served singly or several as a ''plate''. A [[rib steak]] from beef is a popular choice used in many [[cuisine]]s. [[Pork rib]]s, including [[spare ribs]] are popular in [[European cuisine|European]] and [[Asian cuisine]].

==Animated images==
<gallery>
File:Thoracic Cage with Spine - Anatomy.gif|Thoracic cage with spine 
</gallery>

==See also==
{{Commons category|Ribs (skeleton)}}
{{wiktionary|rib}}

* [[Anatomical terms of location]]
* [[Bone#Terminology|Bone terminology]]
* [[Rib fracture]]
* [[Rib removal]]

==References==
{{Reflist}}


{{Authority control}}
[[Category:Thorax (human anatomy)]]
[[Category:Skeletal system]]