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“Yesterday is history. Tomorrow is a mystery. Today is a gift. That’s why we call it ‘The Present’.” – Eleanor Roosevelt

Human Skeletal System


 

The human skeletal system is one of the major systems in the human body. It is made up of many different bones. In this lesson you can know about human body facts – skeleton & bones facts!

 

What is the skeleton?

 

The internal framework of our body is the skeleton. It is made up of bones. Bones help muscles to act as levers to move the legs, arms and other body parts. We could no longer move our body without bones. In fact, you will look like a huge blob of jelly, without the skeleton.

 

blob-of-jelly

Have you ever thought that you would look like a huge blob of jelly without your skeleton?

 

What does the skeleton do?

 

Following is a list of things that the skeleton does;

 

1. The skeleton provides shape and support to the body.

2. It protects the internal organs such as the brain, the heart,  and the lungs and keep them in their proper place.

3. It helps us to move as our muscles are attached to our bones.

4. Bones in the skeleton help producing blood cells.

 

How many bones are there in the human skeleton?

 

Our human skeletal system is made up of about 300 bones at birth. As the body matures, some of these bones gradually, fuse together to form one bone. Therefore, by adulthood the human skeleton only consists of 206 bones.

 

Human Skeletal System

 

human skeletal system

Human Skeletal System

 

 

The two main divisions of the human skeletal system

 

The human skeletal system is divided into two main divisions. They are;

 

1. The Axial Skeleton

2. The Appendicular Skeleton

 

 

The Axial Skeleton

 

The axial skeleton consists of the skull bones, sternum, spine (vertebral column) and the rib cage. The axial skeleton contains 80 bones all together.

 

the-axial-skeleton

Bones in the axial skeleton

 

The Skull

 

The skull is a bony structure that supports the structures of the face and provides a protective cavity for the brain. It consists of the following parts;

 

1. The cranium

2. The facial bones

3. The mandible or the jaw bone

 

human skeletal system - the skull

Parts of the skull

 

The Sternum

 

The sternum is also called the breastbone. It is a long flat bone, which is located in the centre of the chest and connects to the ribs with cartilage . The sternum consists of three main parts;

 

1. The manubrium

2. Sternal body

3. The xiphoid process

 

human skeletal system - sternum

Parts of the sternum

 

The Rib Cage

 

The rib cage is formed by the spine (vertebral column), sternum, ribs and cartilages. It encloses the heart and lungs. There are three types of ribs in the rib cage. They are;

 

1. True ribs

2. False ribs

3. Floating ribs

 

human skeletal system - the rib cage

Parts of the rib cage

 

The Spine

 

The spine is also known as the vertebral column or backbone. The human vertebral column consists of 33 vertebrae.  A vertebra (plural – vertebrae) is one of the bony segments of the vertebral column. Vertebrae are irregular bones in the skeleton.

 

human skeletal system - the vertebral column

Parts of the vertebral column

 

 

The Appendicular Skeleton

 

Out of 206 bones in the human skeleton, the appendicular skeleton contains 126 bones. The appendicular skeleton consists of the following bones.

 

Region Types of bones No. of bones all together
Chest girdles Left and right collarbones (clavicle) (2 bones)
Left and right shoulder blades (scapula) (2 bones)
4
Arms and forearms Left and right humerus (2 bones)
Left and right ulna (2 bones)
Left and right radius (2 bones)
6
Hands and wrists Left and right carpals (wrist ) (16 bones)
Left and right metacarpals (10 bones)
Left and right phalanges (fingers) (28 bones)
54
Pelvis (Pelvic girdle) Left and right hip bones (2 bones) 2
Thighs and legs Left and right femur (thigh) (2 bones)
Left and right patella (knee) (2 bones)
Left and right tibia (leg) (2 bones)
Left and right fibula (leg) (2 bones)
8
Feet and ankles Left and right tarsals (ankle) (14 bones)
Left and right metatarsals (10 bones)
Left and right phalanges (toes) (28 bones)
52
Total no. of bones in the appendicular skeleton 126

 

appendicular-skeleton

Bones in the appendicular skeleton

 

The clavicle

 

Also known as the collarbone. It is a long bone that acts as a rod between the shoulder blade (scapula) and the sternum (breastbone) to link them. Collarbone is the only long bone in our body that lies horizontally. There are two clavicles or collarbones in our skeleton. They are;

 

1. The right collarbone

2. The  left collarbone

 

human skeletal system - collarbone

The right and the left collarbones

 

The Scapula

 

The scapula (plural – scapulae) is also known as the shoulder blade. It connects the humerus (upper arm bone) with the collarbone. There are two scapulae.

 

1. The right scapula

2. The left scapula

 

human skeletal system - shoulder bones

The right and the left scapulae

 

The Humerus

 

The humerus (Plural – humeri) is a long bone in the upper arm. It runs from the shoulder to the elbow. There are two humeri.

 

1. The right humerus

2. The left humerus

 

human skeletal system - humerus

The right humerus

 

 

The Radius and the Ulna

 

The radius (also called the radial bone) and the ulna are the two large bones of the forearm. Both run parallel to each other, extending from the elbow to the wrist. The ulna is located at the side of the forearm closest to the body.

 

There are 2 radial bones and 2 ulna bones in the human skeleton. They are;

 

1. Left and right radius

2. Left and right ulna 

 

human skeletal system - radius ulna bones

The left radius and ulna

 

 

 

 

Carpals, Metacarpals and Phalanges of the hand

 

Each human hand consists of 27 bones. Therefore, altogether there are 54 bones in both hands. They are grouped as follows;

 

1. Wrist – Left carpals  (8 bones) and right carpals (8 bones)

2. Left metacarpals (5 bones) and right metacarpals (5 bones)

3. Fingers – Left phalanges (14 bones) and right phalanges (14 bones)

 

The eight short carpal bones of the wrist joint with the bones of the forearm and the bases of the five metacarpal bones of the hand.

 

The heads of the metacarpals joint with the bases of the knuckles, and the heads of the knuckles joint with the phalanges of the fingers and thumb.

 

There are fourteen phalanges to make up the four fingers and thumb. Each finger of the four fingers consists of three bones. The thumb only consists of two bones.

 

human skeletal system - bones of the hand

Bone structure of the left hand

 

The Pelvis

 

This is a symmetrical bone that looks like a basin. The meaning of pelvis is basin in Latin.

 

The pelvis is made of three major bones. These are;

 

1. The hip bone
2. The sacrum
3. The coccyx (tailbone)

 

Connected to either side of the sacrum, the pelvis contains two hip bones. Each hip bone contains three bones fused together. These are;

 

1. The ilium (the top part of the pelvis)
2. The pubis or pubic bone (the middle part of the pelvis)
3. The ischium (the lower part of the pelvis)

 

The pelvic girdle is a ring of bones that connects the vertebral column with the femur of the legs. The pelvic cavity is in the centre of the pelvis. It protects the digestive and reproductive organs and the rectum. The ligaments connected to the pelvis provide movement for running, walking, sitting, standing etc.

 

human skeletal system - pelvis

The Pelvis

 

The Femur

 

The femur is also known as the thigh bone. Thigh bone is the longest and the strongest bone in the human skeletal system. It extends from the hip to the knee. There are two femurs. They are;

 

1. The right femur

2. The left femur

 

human skeletal system - femur

The right femur

 

The Patella

 

This is simply known as the kneecap. Kneecap is a circular-triangular bone. It articulates with the femur. There are two patellas in our skeleton. They are;

 

1. The right patella (The right kneecap)

2. The left patella (The left kneecap)

 

human skeletal system - kneecap

The patella

 

The Tibia and the Fibula

 

The tibia and the fibula are the two long bones in the leg below the knee. The tibia, also known as the shinbone, is the stronger and the larger of the two bones. It connects the knee with the ankle bones. The fibula is the smaller of the two bones and also known as the calf bone. It is the thinnest of all the long bones. There are two tibia bones and two fibula bones. They are;

 

1. Left and right tibia

2. Left and right fibula

 

human skeletal system - right fibula tibia

Right Tibia and Fibula

 

Tarsals, Metatarsals and Phalanges of the foot

 

Each human foot consists of 26 bones. Therefore, altogether there are 52 bones in both feet. They are grouped as follows;

 

1. Ankle – Left tarsals (7 bones) and right tarsals (7 bones)

2. Left metatarsals (5 bones) and right metatarsals (5 bones)

3. Toes – Left phalanges (14 bones) and right phalanges (14 bones)

 

The foot itself can be divided into three parts. they are;

 

1. The hindfoot

2. The midfoot

3. The forefoot

 

The hindfoot forms the heel and the ankle. It contains the largest tarsal bone to form the heel, the talus bone to form the ankle, and another two tarsal bones. The midfoot contains the rest of the tarsal bones. The forefoot consists of the metatarsals and the phalanges.

 

 

human skeletal system - right foot bones

Bone structure of the right foot

 

Now you can get the idea of how each and every bone in the human skeletal system is important to us.