Bones are made from hardened cartilage through a process called ossification. The human body contains 206 bones that make up the skeleton. These bones can be classified as either compact bones or cancellous bones. Compact bones are dense and make up 80% of the bones in our body while cancellous bones have a spongy appearance.
Major Bones of the Skeletal System and Their Functions
The human skeleton creates structure, provides connection and support for muscles, protection for organs and contains bone marrow, which produces red blood cells. Bone formation begins in the embryonic stage and humans reach peak bone mass during early adulthood. A healthy diet containing adequate calcium and exercise helps maintain bone health. Human skeletons can be segmented into 10 bones in the body with more than 20 major bones.
The skull contains the cranium, maxilla and mandible. The bones of the cranium are the upper part of the skull and protect our brains from damage. The maxilla, also known as the upper jaw, assists us with chewing our food, has openings for our nose and forms the lower section of our eye sockets. The mandible, or lower jaw, is made up of two fused joints and is essential for the movement that enables humans to chew food.
The shoulder girdle is made up of the clavicle and scapula. The scapula is commonly referred to as the collarbone and helps to support the shoulder. The scapula, also called the shoulder blade, helps to form the shoulder socket and aid rotational arm movement.
The arm bones consist of the humerus, radius and ulna. The humerus connects with the shoulder socket in the upper arm. The radius and ulna are adjacent in the lower arm. The arm bones connect with muscles, ligaments and the elbow joint to enable arm rotation and movement.
Human hands are especially crucial for creating the dexterity required for tool use that has led to our society today. The main bones in human hands are carpals, metacarpals and phalanges. The carpals and metacarpals are made up of smaller bones for hand movement. The common name for phalanges are fingers and thumbs.
The chest contains the sternum and 24 ribs. The sternum, or breastbone, ribs and thoracic vertebrae make up the ribcage, which helps protect the lungs and heart. With the help of connecting muscles, the ribcage can expand and contract during respiration.
Spines Are the Body's Trunks
Spines are responsible for our posture and shock absorption when we walk or run. Spines also contain the spinal cord, which is made up of nerve fibers that send messages back and forth between the brain and body. The 24 bones in the human spine create an S-shape structure which is divided into three main sections of vertebrae.
The upper section is called the cervical spine and contains seven vertebrae. The next 12 vertebrae make up the thoracic spine. The lower back is made up of five vertebrae called the lumbar section. At the base of the spine, humans have a large triangular bone called the sacrum, followed by the coccyx or tailbone at the very end.
Human pelvic girdles are formed from three bones called the ilium, pubis and ischium. These bones fuse in early adulthood. The pelvic girdle forms the hip socket, where the femur connects.
Three main bones called the femur, tibia and fibula make up human legs. These bones are analogous to the arm bones. The femur is the main bone in the upper leg while the tibia and fibula are in the lower leg. The knee joint, which helps with leg mobility, connects the upper and lower leg.
Ankles contain seven bones which are responsible for the rotation and movement of the feet. The two main ankle bones are the talus and calcaneus. The talus connects with the tibia to form the ankle joint. The large calcaneus, or heel bone, forms the back of the foot.
Two Feet for Walking
Like hands, feet are constructed of many small bones with the main segments called the tarsals, metatarsals and phalanges. The tarsals and metatarsals are responsible for forming the arch in the foot. The arch acts as a lever and helps give humans strength for walking. Phalanges, or toes, are a lot thicker than fingers and assist with locomotion and balance.
- Encyclopaedia Britannica: Compact Bone
- Encyclopaedia Britannica: Bone Formation
- Encyclopaedia Britannica: Human Skeleton
- OrthoInfo: Healthy Bones at Every Age
- Spine Health: Coccyx
- DePuySynthes: Anatomy of the Spine
- ENcyclopaedia Britannica: Clavicle
- Encyclopaedia Britannica: Scapula
- Encyclopaedia Britannica: Tarsal
- Science: Human-Like Hand Use in Australopithecus Africanus