The framework of the human body is the skeletal system. Skeletal system organs include the bones, joints, cartilages, ligaments, tendons and teeth. Bones offer support for the muscles, protect our vital organs, and allow us to eat food. Our joints allow our body to move, twist and bend. Cartilage, like our ears and nose, offer soft structures that are more malleable than bones. Two separate bones are connected by ligaments, and bones and muscles are connected by tendons. Our teeth allow us to bite and chew our food. Skeletal structure is similar among all people around the world, with the greatest diversity occurring between the sexes. We will explore each system in greater detail and provide descriptions for our skeletal structure.
Skeletal System Organs
The adult human body consists of 206 bones. Bones offer a wide variety of purposes for our body. The skull and rib cage are designed to contain the vital organs of our body. Ligaments and tendons are connected the the bones and allow us to move. Small structures, like our hyoid and auditory ossicles are special structures that allow us to swallow and hear. Our spine gives protection to our spinal cord, and it also allows us to bend and is the connection point for our skull, rib cage and pelvis. Our shoulder and pelvis provide support for our body and are where our limbs are connected. Our hands and feet are made from numerous bones. Within our body we have long bones, like our femur; short bones, like the bones in our hands; and flat bones, like the bones of our skull. Within certain bones is our marrow, which produces our blood cells.
Cartilage is soft and flexible tissue that is similar to bones in that it provides structure. Cartilage forms our nose, ears and other organs. It is also found in our joints, which acts to reduce friction between bones that would otherwise be destroyed by friction. Cartilage is pliable, which is why our ears can twist into unusual shapes. If our ears were made of bone, then their exposed position might result in serious damage.
Joints appear throughout our body. Our ability to move turn our head is because of our spine’s ability to twist and turn. Our shoulders and hips allow our arms to move in circles. Our elbows and knees are hinge joints, which allow us to extend or retract our hands and feet. Our wrists and ankles give is the ability to move them in circles. Our fingers and toes are hinge joints as well. Every place in your body that moves, like your jaw, does so because of joints.
Ligaments are made of fibrous collagen tissue. The purpose of the ligaments are to connect two bones to each other. These connections are located at joints, which control and enhance our movements. Our hips, shoulders, elbows and knees are connected by ligaments. People who are double jointed have ligaments that allow them to move their joints further than people who are not double jointed.
Tendons, like ligaments, are also made of fibrous collagen tissue. Tendons connect muscles to bones, which allow the movements of our muscles to cause our bones to move. When a muscle contracts, it pulls the tendon, which causes the bone in the arm to contract. When we walk, lift items, talk or make dinner, we are moving our tendons.
Our teeth allow us to bite and chew our food. Our teeth are connected to our jaw and are incredibly durable. Teeth are one of the most important indicators of our health. Baby teeth are temporary teeth that are able to fit into the mouth of the child. As we age and grow, our permanent teeth develop. Wisdom teeth appear in most people, and some dentists remove them for the comfort of their patients.
Skeletal System Divisions
The skeletal system organs are divided into two types, the axial skeleton and the appendicular skeleton. The axial skeleton, which contains 80 bones, protects our vital viscera and gives our body a central structure. The skull, spine, and rib cage are parts of the axial skeletal division. The appendicular skeleton, which contains 125 bones, allows our body to move and manipulate our world. Our arms and legs are parts of the appendicular skeletal diviosn.
1. Axial Skeleton
The skull is made of the cranium, which protects our brain; the face, which allows us to breath, eat and communicate; and the auditory ossicles, which allow us to hear. The hyoid bone, which is the central structure of our throat, allows to to talk, sing, breath and eat. The spinal column protects the integrity of our spine and provides support for our other organs. Our spine runs from the base of our skull and ends with our tail bone. The thoracic cage, often known as the rib cage, protects our vital organs and provides structure for connective tissue.
2. Appendicular Skeleton
The shoulder girdle contains our clavicle, or collar bone, and our scapula, or shoulder bones. This provides a place for our upper limbs, our arms, forearms and hands, to connect to the rest of our body. Our pelvic bone provides protection and structure to our vital and reproductive organs. It also allows our lower limbs, the leg and feet bones, to connect to our body.
Our bones are classified into four categories based on the size and shape of the bones. These include flat bones, long bones, short bones, and irregular bones.
1. Flat Bones
Flat bones are broad, flat and curved. These include the bones of our rib cage and cranium. These are used for protection of our vital organs and offer surface area for connective tissue. Our rib cage is connected by cartilage that allows it to expand and contract with our breathing.
2. Long Bones
Our legs and arms are examples of long bones. These are longer than they are wide. Long bones also protect and contain blood producing marrow. Long bones give length and strength to our bodies and are connected to powerful muscles and joints.
3. Short Bones
Short bones, such as the bones of our hands and feet, are cube shaped. They are structured to provide maximum range of movement and flexibility. These bones are connected by tissues that allow them to bend in twist in ways that long, flat and irregular bones are unable to.
4. Irregular Bones
Bones such as our pelvic bone, vertebrae and mandible are oddly shaped and difficult to classify. These bones are unique and provide structure for our body. Our spine is made up of a wide variety of differently shaped irregular bones.