Written By Manisha Minni
Last Modified 25-01-2023

Human Skeletal System: Definition, Functions, Disorders

What is our endoskeleton made up of? How do we get a definite shape? Which organ system protects the internal organs of the body? The human skeletal system is the base structure of the human body. A human body has \(206\) bones. The human skeletal system can be divided into two parts namely, the axial skeleton and appendicular skeleton.

The human skeletal system is composed of bones, cartilage, ligaments, and tissues, and it carries \(20\% \) weight of the human body. In this article, we will learn about the human skeletal system, its anatomy, parts, functions, disorders, and much more. Continue reading to learn more!

Learn About Axial Skeleton Here

What is Skeletal System in Human Body?

The skeletal system consists of a framework of bones and a few cartilages. This system has a significant role in movement shown by the body. The skeletal system of humans can be basically divided into two parts axial skeleton and appendicular skeleton.

Diagram of Human Skeletal System

Below we have provided the diagrammatic representation of the human skeletal system:

Anatomy of Human Skeletal System

The skeleton system of a human being has two divisions:

Axial Skeleton
Appendicular Skeleton

The division of the bones in Axial and Appendicular Skeleton is as shown below:

Axial Skeleton

The axial skeleton consists of the skull, the vertebral column, and the thoracic cage. It consists of \(80\) bones.

Components of the Axial Skeleton	Description
Skull	1. The skeletal framework of the head is called the skull. 2. It is a protective cover for the brain, i.e. cranium and it supports the structure of the face. 3. The two parts of the skull are the cranium and mandible. 4. The skull has a total of \(22\) bones.
Vertebral column	1. A group of bones that extends from the skull base to the pelvis is called vertebral bones. It is also known as the spine. 2. Vertebral bones in child \(= 33\) 3. Vertebral bones in adult \(= 26\)
Thoracic cage / Rib cage	1. The thoracic cage is a bony structure consisting of ribs and the sternum. It is also known as a rib cage. 2. It is made up of \(25\) bones, i.e. \(1\) sternum and \(24\) ribs. 3. It protects the organs of the heart and lungs. 4. True ribs: \(7\) pairs (\(14\) bones) – First seven pairs 5. False ribs: \(3\) pairs (\(6\) bones) – \({{\rm{8}}^{{\rm{th}}}}{\rm{,}}{{\rm{9}}^{{\rm{th}}}}\) and \({\rm{1}}{{\rm{0}}^{{\rm{th}}}}\) pairs 6. Floating ribs: \(2\) pairs (\(4\) bones) \({\rm{1}}{{\rm{1}}^{{\rm{th}}}}\)- and \({\rm{1}}{{\rm{2}}^{{\rm{th}}}}\) pairs

Additional Facts: In some human \({\rm{1}}{{\rm{3}}^{{\rm{th}}}}\) and \({\rm{1}}{{\rm{4}}^{{\rm{th}}}}\) floating ribs are found, which are known as Gorilla Ribs.

Appendicular Skeleton

The appendicular skeleton consists of bones of upper and lower limbs, pelvic girdle, and pectoral girdle. It consists of \(126\) bones.

Components of the Appendicular Skeleton	Description
Pectoral girdle	1. The pectoral girdle is also known as the shoulder girdle. 2. It is responsible for attaching the upper limbs to the axial skeleton. 3. It comprises \(4\) bones, i.e. \(2\) clavicles and \(2\) scapula.
Pelvic girdle	1. The pelvic girdle is a composition of bones that functions as the point of attachment of the lower limbs to the axial skeleton. 2. It comprises \(2\) bones, i.e. pubic or coxal bone.
Bones of arms or forelimbs	1. The upper limb is composed of the bones of the arm, the forearm, the wrist, and the hand. 2. It comprises \(60\) bones, i.e. \(30\) bones in each hand.
Bones of legs or hindlimbs	1. The lower limb is composed of the thighs, legs, and feet. 2. It comprises \(60\) bones, i.e. \(30\) bones in each leg.

What are the 5 Main Parts of the Skeletal System?

The parts or components of the skeletal system are bones, joints, cartilage, ligaments, and tendons.

1. Bones:

Bones form the skeleton of a human body. The bone is composed of calcium phosphate and calcium carbonate. It protects the internal organs. In a human child, the number of bones is \(270\) that decreases to \(206\) in an adult.

Types of bones	Features	Functions	Examples
Long	It is cylindrical in shape and it is longer as compared to its breadth.	It provides movement and support to the human body.	Femur, tibia, fibula, metatarsals, ulna, radius, metacarpals, phalanges.
Short	It is cubical in shape and approximately equal in length, width, and thickness.	It provides stability and support while allowing movement.	Carpals and tarsals.
Flat	It is thin and curved.	Points of attachment for muscles, protectors of internal organs.	Sternum, ribs, scapula, cranial bones.
Irregular	Complex shape	Protect internal organs, provide movement, and support.	Vertebrae, facial bones.
Sesamoid	Small and round, embedded in tendons	Protect tendons from excessive forces, allow effective muscle action.	Patellae

2. Joints

The Joint is the connecting point of two or multiple bones. Joints help in the movement of the human body.

Types of Joints

Name of Joints	Mobility	Location
Fibrous Joint	Fibrous joints do not allow any movement.	Between skull bones
Cartilaginous Joint	Cartilaginous joints permit limited movements.	Between the adjacent vertebrae in the vertebral column
Synovial Joint	Synovial joints allow considerable movement.	Between two bones having synovial fluid
Ball and Socket Joint	Ball and socket joints provide movement in multiple planes.	Between humerus and pectoral girdle
Saddle Joint	The saddle joint shows movement in two planes.	Between the carpal and metacarpal of the thumb
Hinge Joint	Hinge joints provide movement in one plane.	Found in the knee and elbow joint
Condyloid Joint	Condyloid joints allow movement in two planes.	In wrist bones
Pivot Joint	The pivot joint helps in rotation around the axis.	Between atlas and axis and wrist bones
Gliding Joint	The gliding joint allows sliding movements.	Between the carpals

3. Cartilage: Cartilage is a soft, flexible tissue that acts as padding to cover and protect the long bones at the joints and nerves. It is a connective tissue between two or more bones that facilitates movement.

Types of Cartilage

The types of cartilages are:

Hyaline	Elastic	Fibrous
It is a crystal-clear matrix with fewer fibres and forms articular surfaces at the joints of long bones.	It has numerous yellow elastic fibres found in-ear, pinna, external auditory, meatus, eustachian tube, etc.	It has numerous white fibres found in pubic symphysis and sternoclavicular joints.

4. Ligaments: Ligaments are like bands made of rigid and flexible tissues which connect the bones of the body. It limits the amount of movement between bones.

5. Tendon: The tissues that attach the muscle to the bone are called a tendon. It helps in resisting tensile forces while transmitting forces from muscle to bone.

Functions of Human Skeletal System

The main functions of the Human Skeletal System are:

Support: It supports the human body by keeping it upright and providing structure for muscle and tissue attachment.
Posture: It helps in maintaining a correct posture to our body.
Protection: It reduces the risk of injuries by protecting the internal organs of the human body.
Movement: It is also responsible for the direction of the human body. The joints act like levers that allow muscles to produce motion by contracting and pulling on the bones.
Blood cell production: The bone marrow is available in some bones, produces red blood cells. The pelvis, sternum, humerus and femur are the bones that contain bone marrow.
Storage of minerals: The bones are made of minerals and are a reservoir for minerals like calcium, iron, potassium, and phosphorus.

Disorders of Human Skeletal System

The disorders of the human skeletal system are as follows:

Arthritis: Inflammation of joints. It is of three types: Rheumatoid arthritis, osteoarthritis, and Gout.
Osteoporosis: Age-related disorder characterized by decreased bone mass and increased chances of fractures. Decreased levels of estrogen are a common cause.
Gout: Inflammation of joints due to accumulation of uric acid crystals.

Summary

The skeletal system works as a supporting structure of the human body. It consists of bones of the skeleton, cartilages, ligaments, and other tissues that interconnect bones. Its function is to support, protect, leverage, production of blood cells, and storage of minerals. It also provides stability to the human body. The femur is the longest bone in the human skeletal system. Furthermore, it is important to note that a human body has 206 bones.

FAQs on Human Skeletal System

Q.1. Name the longest bone in the human body.
Ans: The femur is the longest bone in the human body.

Q.2. What is the human skeletal system?
Ans: Skeletal system consists of a framework of bones and a few cartilages. This system has a significant role in movement shown by the body.

Q.3. Name the bone which is not attached to any other bone in the human body.
Ans: Hyoid bone is not attached to any other bone in the human body.

Q.4. How many bones does an adult human body have?
Ans: An adult human body has 206 bones.

Q.5. What is arthritis?
Ans: Inflammation of joints is called arthritis.

Q.6. What are the functions of the human skeletal system?
Ans: The human skeletal system functions to provide support, posture, movement, blood cell production, and storage of minerals.

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Human Skeletal System: Definition, Functions, Disorders