Rib - wikipedia Rib This article is about the part of the skeleton. For other uses, see Rib ( disambiguation ). This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( June 2008 ) Rib The human rib cage ( Source : Gray 's Anatomy of the Human Body, 20th ed. 1918 ) Detail of a single human rib Details Identifiers Latin costae MeSH D012272 FMA 7574 Anatomical terminology ( edit on Wikidata ) In vertebrate anatomy, ribs ( Latin : costae ) are the long curved bones which form the rib cage. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax. In some animals, especially snakes, ribs may provide support and protection for the entire body. Contents 1 Human anatomy 2 In animals 3 Additional images 4 See also 5 References Human anatomy Main article : Rib cage Humans have 24 ribs ( 12 pairs ). The first seven sets of ribs, known as `` true ribs '' ( costae verae ) also known as vertebrosternal ribs, are directly attached to the sternum through the costal cartilage. Rib 1 is unique and harder to distinguish than other ribs. It is a short, flat, C - shaped bone. 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 have a more traditional appearance and become longer and less curved as they progress downwards. The following five sets are known as `` false ribs '' ( costae spuriae ), three of these sharing a common cartilaginous connection to the sternum, while the last two ( eleventh and twelfth ribs ) are termed floating ribs ( costae fluctuantes ) or vertebral ribs. They are attached to the vertebrae only, and not to the sternum or cartilage coming off of the sternum. Some people lack one of the two pairs of floating ribs, while others have a third pair. 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. X-ray image of human chest, with ribs labelled The ribcage 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. In animals Skeleton of a dog showing the location of the ribs Ribcage of Eptesicus fuscus ( Big Brown Bat ) In 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. Sharks, for example, have no dorsal ribs, and only very short ventral ribs, while lampreys have no ribs at all. In some teleosts, there may be additional rib - like bones within the muscle mass. Tetrapods, however, only ever have a single set of ribs which are probably homologous with the dorsal ribs of fishes. In the early tetrapods, every vertebra bore a pair of ribs, although those on the thoracic vertebrae are typically the longest. The sacral ribs were stout and short, since they formed part of the pelvis, connecting the backbone to the hip bones. In most subsequent forms, many of these early ribs have been lost, and in living amphibians and reptiles, there is great variation in rib structure and number. For example, turtles have only eight pairs of ribs, which are developed into a bony or cartilagenous carapace and plastron, while snakes have numerous ribs running along the full length of their trunk. Frogs typically have no ribs, aside from a sacral pair, which form part of the pelvis. In birds, ribs are present as distinct bones only on the thoracic region, although small fused ribs are present on the cervical vertebrae. The thoracic ribs of birds possess a wide projection to the rear ; this uncinate process is an attachment for the shoulder muscles. Usually dogs have 26 ribs. Mammals usually also only have distinct ribs on the thoracic vertebra, although fixed cervical ribs are also present in monotremes. In marsupials and placental 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 ribs are never found in mammals. Additional images Human ribs ( shown in red ). It consists of 24 ribs. Left and right of first rib to twelfth rib. Spinal cord. Spinal membranes and nerve roots. Deep dissection. Posterior view. Spinal cord. Spinal membranes and nerve roots. Deep dissection. Posterior view. Spinal cord. Spinal membranes and nerve roots. Deep dissection. Posterior view. See also Wikimedia Commons has media related to Ribs ( skeleton ). Look up rib in Wiktionary, the free dictionary. Anatomical terms of location Bone terminology Rib fracture Rib removal Ribs ( food ) References ^ Jump up to : Saladin, K.S. ( 2010 ). Anatomy and Physiology : The Unity of Form and Function ( 5th ed. ). New York, NY : McGraw - Hill. ^ Jump up to : Romer, Alfred Sherwood ; Parsons, Thomas S. ( 1977 ). The Vertebrate Body. Philadelphia, PA : Holt - Saunders International. pp. 170 -- 173. ISBN 0 - 03 - 910284 - X. Clinically Oriented Anatomy, 4th ed. Keith L. Moore and Robert F. Dalley. pp. 62 -- 64 Human regional anatomy Head Ear Face Cheek Chin Eye Mouth Nose Forehead Jaw Occiput Scalp Temple Neck Adam 's apple Throat Trunk Abdomen Waist Midriff Navel Back Thorax Breast Pelvis Sex organs Limbs Arm Shoulder Axilla Brachium Elbow Forearm Wrist Hand Finger Thumb Index Middle Ring Little Leg Buttocks Hip Thigh Knee Calf Foot Ankle Heel Sole Toe Other Écorché General anatomy : systems and organs, regional anatomy, planes and lines, superficial axial anatomy, superficial anatomy of limbs GND : 4178211 - 2 NDL : 00569649 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Rib&oldid=844969569 '' Categories : Thorax ( human anatomy ) Skeletal system Hidden categories : Pages with unresolved properties Articles needing additional references from June 2008 All articles needing additional references Articles containing Latin - language text All articles with unsourced statements Articles with unsourced statements from November 2016 Wikipedia articles with GND identifiers Wikipedia articles with NDL identifiers Talk Contents About Wikipedia ܐܪܡܝܐ Atikamekw Avañe'ẽ Авар Azərbaycanca Башҡортса Беларуская Български Bosanski Brezhoneg Català Чӑвашла Čeština ChiShona Cymraeg Dansk Deutsch Eesti Emiliàn e rumagnòl Español Esperanto Euskara فارسی Français Gaeilge Gàidhlig Galego 贛 語 客家 語 / Hak - kâ - ngî 한국어 हिन्दी Hrvatski Ido Bahasa Indonesia Íslenska Italiano עברית Basa Jawa Қазақша Лакку Latina Latviešu Lietuvių Magyar Македонски मराठी Bahasa Melayu Mìng - dĕ̤ng - ngṳ̄ Nederlands नेपाल भाषा 日本 語 Norsk Norsk nynorsk Occitan Polski Português Română Русский Scots Shqip Simple English Slovenčina Slovenščina کوردی Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் తెలుగు ไทย Türkçe Українська ئۇيغۇرچە / Uyghurche Tiếng Việt West - Vlams Winaray 粵語 Žemaitėška 中文 Bahasa Hulontalo 73 more Edit links This page was last edited on 8 June 2018, at 12 : 39 ( UTC ). 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Question: how many ribs does a human body have
Answer: 24 ribs (12 pairs)