{"id":55190,"date":"2019-08-26T15:33:48","date_gmt":"2019-08-26T15:33:48","guid":{"rendered":"https:\/\/www.mometrix.com\/academy\/?page_id=55190"},"modified":"2026-03-26T13:00:13","modified_gmt":"2026-03-26T18:00:13","slug":"skeletal-system","status":"publish","type":"page","link":"https:\/\/www.mometrix.com\/academy\/skeletal-system\/","title":{"rendered":"Skeletal System"},"content":{"rendered":"\n\t\t\t<div id=\"mmDeferVideoEncompass_iNeWdY8wyZ0\" style=\"position: relative;\">\n\t\t\t<picture>\n\t\t\t\t<source srcset=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.webp\" type=\"image\/webp\">\n\t\t\t\t<source srcset=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.png\" type=\"image\/jpeg\"> \n\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" loading=\"eager\" id=\"videoThumbnailImage_iNeWdY8wyZ0\" data-source-videoID=\"iNeWdY8wyZ0\" src=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.png\" alt=\"Skeletal System Video\" height=\"464\" width=\"825\" class=\"size-full\" data-matomo-title = \"Skeletal System\">\n\t\t\t<\/picture>\n\t\t\t<\/div>\n\t\t\t<style>img#videoThumbnailImage_iNeWdY8wyZ0:hover {cursor:pointer;} img#videoThumbnailImage_iNeWdY8wyZ0 {background-size:contain;background-image:url(\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/02\/319-skeletal-system-1.webp\");}<\/style>\n\t\t\t<script defer>\n\t\t\t  jQuery(\"img#videoThumbnailImage_iNeWdY8wyZ0\").click(function() {\n\t\t\t\tlet videoId = jQuery(this).attr(\"data-source-videoID\");\n\t\t\t\tlet helpTag = '<div id=\"mmDeferVideoYTMessage_iNeWdY8wyZ0\" style=\"display: none;position: absolute;top: -24px;width: 100%;text-align: center;\"><span style=\"font-style: italic;font-size: small;border-top: 1px solid #fc0;\">Having trouble? <a href=\"https:\/\/www.youtube.com\/watch?v='+videoId+'\" target=\"_blank\">Click here to watch on YouTube.<\/a><\/span><\/div>';\n\t\t\t\tlet tag = document.createElement(\"iframe\");\n\t\t\t\ttag.id = \"yt\" + videoId;\n\t\t\t\ttag.src = \"https:\/\/www.youtube-nocookie.com\/embed\/\" + videoId + \"?autoplay=1&controls=1&wmode=opaque&rel=0&egm=0&iv_load_policy=3&hd=0&enablejsapi=1\";\n\t\t\t\ttag.frameborder = 0;\n\t\t\t\ttag.allow = \"autoplay; fullscreen\";\n\t\t\t\ttag.width = this.width;\n\t\t\t\ttag.height = this.height;\n\t\t\t\ttag.setAttribute(\"data-matomo-title\",\"Skeletal System\");\n\t\t\t\tjQuery(\"div#mmDeferVideoEncompass_iNeWdY8wyZ0\").html(tag);\n\t\t\t\tjQuery(\"div#mmDeferVideoEncompass_iNeWdY8wyZ0\").prepend(helpTag);\n\t\t\t\tsetTimeout(function(){jQuery(\"div#mmDeferVideoYTMessage_iNeWdY8wyZ0\").css(\"display\", \"block\");}, 2000);\n\t\t\t  });\n\t\t\t  \n\t\t\t<\/script>\n\t\t\n<p><script>\nfunction iyb_Function() {\n  var x = document.getElementById(\"iyb\");\n  if (x.style.display === \"none\") {\n    x.style.display = \"block\";\n  } else {\n    x.style.display = \"none\";\n  }\n}\n<\/script><\/p>\n<div class=\"moc-toc hide-on-desktop hide-on-tablet\">\n<div><button onclick=\"iyb_Function()\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2024\/12\/toc2.svg\" width=\"16\" height=\"16\" alt=\"show or hide table of contents\"><\/button><\/p>\n<p>On this page<\/p>\n<\/div>\n<nav id=\"iyb\" style=\"display:none;\">\n<ul>\n<li class=\"toc-h2\"><a href=\"#Skeletal_System_Functions\" class=\"smooth-scroll\">Skeletal System Functions<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Axial_Skeleton\" class=\"smooth-scroll\">Axial Skeleton<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Appendicular_Skeleton\" class=\"smooth-scroll\">Appendicular Skeleton<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Bone_Characteristics\" class=\"smooth-scroll\">Bone Characteristics<\/a><\/li>\n<\/ul>\n<\/nav>\n<\/div>\n<div class=\"accordion\"><input id=\"transcript\" type=\"checkbox\" class=\"spoiler_button\" \/><label for=\"transcript\">Transcript<\/label>\n<div class=\"spoiler\" id=\"transcript-spoiler\">\n<p>Hey, guys! Welcome to this Mometrix video about the skeletal system.<\/p>\n<p>Every one of the systems in the body plays a critical role in our ability to function, but the skeletal system is particularly important. Without a skeletal system we wouldn\u2019t be able to walk, and we would have no way to protect our vital organs like our <a class=\"ylist\" href=\"https:\/\/www.mometrix.com\/academy\/heart-anatomy-and-physiology\/\">heart<\/a> and brain. That\u2019s why the skeletal system and its network of 206 bones are so important to us. <\/p>\n<h2><span id=\"Skeletal_System_Functions\" class=\"m-toc-anchor\"><\/span>Skeletal System Functions<\/h2>\n<p>\nSo let\u2019s talk about the skeletal system\u2019s main functions. There are six of them, and they\u2019re all important.<\/p>\n<h3><span id=\"Support\" class=\"m-toc-anchor\"><\/span>Support<\/h3>\n<p>\nThe skeletal system supports our bodies and the organs and tissues within it. Our skeleton gives us shape and holds us up, so without a skeletal system, we couldn\u2019t stand.<\/p>\n<h3><span id=\"Movement\" class=\"m-toc-anchor\"><\/span>Movement<\/h3>\n<p>\nThe skeletal system gives us the ability to move. The bones allow movement by acting like a kind of pulley. When muscles contract, they pull the skeletal bones, which cause movement. Joints also play a critical part in movement because they determine flexibility. So, while you can bend your knee up to a 135-degree angle, your back\u2014the thoracic spine\u2014only bends about 60 degrees, at most. The bottom line is this\u2014you need muscles, bones, and joints to move and bend and stretch.<\/p>\n<h3><span id=\"Protection\" class=\"m-toc-anchor\"><\/span>Protection<\/h3>\n<p>\nOur skeletons protect our organs. Our skull protects our <a class=\"ylist\" href=\"https:\/\/www.mometrix.com\/academy\/brain-anatomy\/\">brain<\/a>. Our rib cage holds up and protects our lungs and heart. The spinal cord, well, that\u2019s protected by the vertebrae.<\/p>\n<h3><span id=\"Production_of_Blood_Cells\" class=\"m-toc-anchor\"><\/span>Production of Blood Cells<\/h3>\n<p>\nAnd while those are some of the obvious ways our skeleton works for us, there are some less obvious ones. We need our skeletal system to produce blood cells. There\u2019s a process called hematopoiesis that takes place in the skeletal system. That\u2019s blood cell development, both red blood cells, which transport oxygen, and white blood cells, which fight infection. In other words, this is the process by which the body replenishes its blood system.<\/p>\n<h3><span id=\"Mineral_Storage\" class=\"m-toc-anchor\"><\/span>Mineral Storage<\/h3>\n<p>\nNot only that, the skeleton acts as a storage system for the minerals calcium and phosphorous, and we need both for our nerves, muscles, and body organs to function. This results in an interesting tug of war within our own body. You see, the skeleton needs calcium and phosphorous to stay strong while at the same time distributing these minerals to other parts of the body that need them as well. So, if the skeleton shares too much of its mineral base it can become weak and lead to bone problems.<\/p>\n<h3><span id=\"Endocrine_Regulation\" class=\"m-toc-anchor\"><\/span>Endocrine Regulation<\/h3>\n<p>\nLastly, the skeletal system is the main cog in the endocrine regulation which means it plays a big role in regulating energy metabolism. This is a relatively recent finding since the research study wasn\u2019t published until 2007. The study showed bones release osteocalcin, a protein hormone, that regulates insulin productivity and sensitivity.<\/p>\n<p>Now that we know the skeletal system\u2019s six main functions, let\u2019s look at the two parts of the skeletal system.<\/p>\n<h2><span id=\"Axial_Skeleton\" class=\"m-toc-anchor\"><\/span>Axial Skeleton<\/h2>\n<p>\nThe axial skeleton has 80 bones made up of the skull, inner ear ossicles, hyoid bone, vertebral column, and the ribs and sternum, which is called the bony thorax. Taken together, this means that the axial skeleton protects our central nervous system. Let\u2019s take a look at the axial skeleton in more detail.<\/p>\n<p>The skull has 28 bones that protect our head and face and contains the cranial and facial bones. Each bone has its own function. Let\u2019s start with the cranial bones.<\/p>\n<h3><span id=\"Cranial_Bones\" class=\"m-toc-anchor\"><\/span>Cranial Bones<\/h3>\n<p>\nThe cranial bones include the parietal, the temporal, frontal, occipital, sphenoid, and ethmoid bones. The two <strong>parietal bones<\/strong> are the flat bones on each side of your head, located behind the frontal bone The <strong>temporal bones<\/strong> are located under the parietal bones. These two irregular shaped bones are at the base and sides of the skull and house the ear structures.<\/p>\n<p>Then there\u2019s the <strong>frontal bone<\/strong>. That\u2019s your forehead, and it also contains the eye sockets. The <strong>occipital bone<\/strong> is located at the back of the skull and it has an opening at the bottom. It\u2019s from that opening that the spinal cord connects to the brain. The <strong>sphenoid bone<\/strong> forms a large part of the base of your skull. The <strong>ethmoid bone<\/strong>, located in front of the sphenoid bone, forms a part of the nasal cavity.<\/p>\n<h3><span id=\"Facial_Bones\" class=\"m-toc-anchor\"><\/span>Facial Bones<\/h3>\n<p>\nNow let\u2019s look at the facial bones, which have their own unique functions. The facial bones include the maxilla, zygomatic, mandible, nasal, palatine, concha, lacrimal, and vomer bones.<\/p>\n<p>The <strong>maxilla bone<\/strong> holds the upper teeth in place and forms the upper jaw. The <strong>zygomatic bone<\/strong>, despite the name, is an easy one to remember because it\u2019s commonly referred to as the cheekbone. The bone also forms the outer side of the eye socket. The <strong>lower jaw bone<\/strong>, called the mandible bone, lets us open and close our mouth and chew since the bone houses our lower teeth.<\/p>\n<p>The <strong>nasal bone<\/strong> is an easy one. It\u2019s those two bones in the middle of our face that make up the bridge of our nose. The <strong>palatine bone<\/strong>, that\u2019s an L-shaped bone that forms the nasal and oral cavities. The <strong>inferior nasal concha<\/strong> is a thin, spongy and bony plate that forms the lower part of the nasal cavity\u2019s lateral wall. The <strong>lacrimal bone<\/strong> is a small and thin bone\u2014actually, it\u2019s the smallest and thinnest in the skull\u2014and it forms part of the eye socket. And the <strong>vomer bone<\/strong> separates the left and right nasal cavity.<\/p>\n<h3><span id=\"Vertebral_Column\" class=\"m-toc-anchor\"><\/span>Vertebral Column<\/h3>\n<p>\nLet\u2019s move on to the bones in our back. The vertebral column has 33 bones and we\u2019ll describe them here.<\/p>\n<p>The <strong>cervical vertebrae<\/strong> are the neck vertebrae that run right below the skull. The cervical spine contains seven vertebrae each designated C1 through C7. The first two vertebrae have more specialized functions, and each have their own name. The C1 vertebrae, called the atlas, connects to the occipital bone and supports the base of the skull. The C2 vertebrae, called the axis, allows the head to rotate. The C3, C4, C5, and C6 vertebrae all have the same characteristics, with a vertebral body, arch, and facet joints. The C7, at the bottom of the spine, connects with the top of the Thoracic spine.<\/p>\n<p>Speaking of which, the <strong>thoracic spine<\/strong> has 12 vertebrae. Located in the upper back, the ribs connect to the thoracic spine and protect many of our vital organs and our spinal cord. The thoracic cage itself contains the ribs and the sternum.<\/p>\n<p>The <strong>lumbar spine<\/strong> has 5 vertebrae (L1 to L5), located in the lower back, where the spine curves in towards the abdomen. The lumbar vertebrae support the weight of the entire torso and are most prone to injury.<\/p>\n<p>The <strong>sacrum<\/strong> is a large bone made up of 5 fused vertebrae at the base of the spine and is part of the pelvic cavity, while the coccyx is made up of 4 small fused bones that can really, really hurt if you fall on it. Most people know it as the tailbone.<\/p>\n<p>So that\u2019s the axial skeleton. <\/p>\n<h2><span id=\"Appendicular_Skeleton\" class=\"m-toc-anchor\"><\/span>Appendicular Skeleton<\/h2>\n<p>\nThe appendicular skeleton has 126 bones that cover our arms, legs, hands, feet, our pelvic girdle, and our shoulder girdle. That means the appendicular skeleton governs movement. The appendicular skeleton can be subdivided into four areas.<\/p>\n<h3><span id=\"Pectoral_Girdle\" class=\"m-toc-anchor\"><\/span>Pectoral Girdle<\/h3>\n<p>\nThe pectoral girdle covers the clavicle and scapula, which connect the upper extremities to the trunk. The clavicle is commonly known as the collarbone, and the scapula as the shoulder blade.<\/p>\n<h3><span id=\"Upper_Extremities\" class=\"m-toc-anchor\"><\/span>Upper Extremities<\/h3>\n<p>\nThe upper extremities (your arm) includes the humerus, radius, ulna, carpals, metacarpals, and phalanges.<\/p>\n<h3><span id=\"Pelvic_Girdle\" class=\"m-toc-anchor\"><\/span>Pelvic Girdle<\/h3>\n<p>\nThe pelvic girdle, your hip bone, serves as the attachment mechanism for the lower limbs.<\/p>\n<h3><span id=\"Lower_Extremities\" class=\"m-toc-anchor\"><\/span>Lower Extremities<\/h3>\n<p>\nThe lower extremity, or your legs, cover the femur, tibia, fibula, patella, tarsals, metatarsals, and phalanges.<\/p>\n<p>So as we can see, the skeletal system controls movement and protects our vital organs. Not only that, relatively new research shows how the skeletal system plays a role in regulating energy metabolism. <\/p>\n<p>Now, let\u2019s take a look at the bones that play such an important part in the skeletal system. <\/p>\n<h2><span id=\"Bone_Characteristics\" class=\"m-toc-anchor\"><\/span>Bone Characteristics<\/h2>\n<p>\nWe know that the skeletal system is made up of bones. But what exactly are bones, and what other functions do they have?<\/p>\n<p>Bones are connective tissue, and some bones are more rigid than others. That\u2019s why bones have two classifications.<\/p>\n<h3><span id=\"Compact_Bones\" class=\"m-toc-anchor\"><\/span>Compact Bones<\/h3>\n<p>\nThere are compact bones, which are dense and rigid and make up much of the skeleton\u2019s hard structure. Compact bones are stronger. They support the body, protect vital organs, and are the engine that power movement.  Compact bones also release calcium and phosphorus into the body when it needs it. The body\u2019s long bones, like the tibia, femur, and fibula, are examples of compact bones.<\/p>\n<h3><span id=\"Cancellous_Bones\" class=\"m-toc-anchor\"><\/span>Cancellous Bones<\/h3>\n<p>\nCancellous bones are located within the compact bones. They\u2019re softer and spongier, which is why these bones are often called spongy bone. What do they do? They control the production of red blood cells, and you\u2019ll also find nerves and bone marrow in this spongy bone.<\/p>\n<p>Both compact and spongy bone is found in most bones. Compact bone is the outer shell around spongy bone.<\/p>\n<h3><span id=\"Bone_Shapes\" class=\"m-toc-anchor\"><\/span>Bone Shapes<\/h3>\n<p>\nBone also comes in different shapes, and each with its own purpose. The flat bones, like the sternum and cranium, protect organs. The long bones, like the femur and tibia, support weight.  The cube-shaped short bones, like the carpals in your hand and tarsals in your ankle, provide stability. The irregular bones, like the ones of the vertebrae and pelvis, protect organs. Lastly, the sesamoid bones are small round bones embedded in tendons, such as the kneecap, which protect tendons from stress and wear.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2021\/12\/image158.png\" alt=\"Different Bone shapes\" width=\"600\" height=\"600\" class=\"aligncenter size-full wp-image-105614\" srcset=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2021\/12\/image158.png 800w, https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2021\/12\/image158-300x300.png 300w, https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2021\/12\/image158-150x150.png 150w, https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2021\/12\/image158-768x768.png 768w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><\/p>\n<p>So that\u2019s our overview of the skeletal system, the bones that help us walk, protect our internal organs, produce blood cells, and help with insulin productivity and sensitivity.<\/p>\n<ul class=\"citelist\">\n<li><a href=\"https:\/\/www.ptdirect.com\/training-design\/anatomy-and-physiology\/the-skeletal-system\"target=\"_blank\">\u201cThe Skeletal System \u2014 PT Direct.\u201d 2010. Ptdirect.com<\/a><\/li>\n<li><a href=\"https:\/\/lumbarspineassessment.wordpress.com\/examination\/active-range-of-motion\/\"target=\"_blank\">\u201cActive Range of Motion.\u201d 2012. Lumbar Spine Assessment. October 3, 2012<\/a><\/li>\n<li><a href=\"https:\/\/doi.org\/10.1242\/dev.083147\"target=\"_blank\">Jagannathan-Bogdan, M., and L. I. Zon. 2013. \u201cHematopoiesis.\u201d Development 140 (12): 2463\u201367<\/a><\/li>\n<li><a href=\"https:\/\/www.healthline.com\/health\/cranial-bones\"target=\"_blank\">Seladi-Schulman, Jill. 2018. \u201cCranial Bones Overview.\u201d Healthline<\/a><\/li>\n<li><a href=\"https:\/\/medical-dictionary.thefreedictionary.com\/inferior+nasal+concha\"target=\"_blank\">\u201cInferior Nasal Concha.\u201d 2020. TheFreeDictionary.com<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n<div class=\"home-buttons\">\n<p><a href=\"https:\/\/www.mometrix.com\/academy\/biology\/\">Return to Biology Videos<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Return to Biology Videos<\/p>\n","protected":false},"author":1,"featured_media":91459,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":{"0":"post-55190","1":"page","2":"type-page","3":"status-publish","4":"has-post-thumbnail","6":"page_category-anatomy-and-physiology-videos","7":"page_type-video","8":"subject_matter-science"},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/pages\/55190","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/comments?post=55190"}],"version-history":[{"count":5,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/pages\/55190\/revisions"}],"predecessor-version":[{"id":260803,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/pages\/55190\/revisions\/260803"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/media\/91459"}],"wp:attachment":[{"href":"https:\/\/www.mometrix.com\/academy\/wp-json\/wp\/v2\/media?parent=55190"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}