Biological aspects of a human endoskeleton

November 23, 2022by wahaj

Embedded within the human body’s muscular system is the endoskeleton that imparts requisite stiffness and support for retaining upright stature. It not only upholds impeccable body shape but also assists in locomotion and safeguards delicate body organs. The biological aspects of the endoskeleton are substantial, it grants multiple benefits that couldn’t be denied.

Status of endoskeleton

The endoskeleton secures significant status within the human body providing major purposes like:

  • This hard structure supports the body without which the human body will be like jelly.
  • It stores lipids and minerals such as calcium, and phosphorous which when needed by the body are released into the bloodstream. The human endoskeleton has regeneration power, it disintegrates and then restores itself utilizing minerals we intake.
  • Certain delicate organs within the human body are protected by an endoskeleton. A good example of this is the lungs sheltered by the ribcage and the brain confined within the skull.
  • Some of the bones have stem cells to yield blood cells.
  • The endoskeleton allows body movement

Endoskeleton divisions

The human endoskeleton is a network of bones linked together through joints. These joinery junctions are held in place by soft tissues i.e. ligaments, muscles, and tendons. Endoskeleton in coordination with muscular system succor body locomotion. For convenience and the sake of learning biological aspects of an endoskeleton, this complex system is divided into axial skeleton and appendicular skeleton.

Axial skeleton

Focusing on the central axis of the human body axial skeleton comprises the skull, throat bone (hyoid bone), vertebral column, and ribcage. To describe precisely, the axial skeleton provides protection to the organs like the brain, lungs, heart and spinal cord. Muscles that help in the movement of the neck, head and trunk are attached to the axial skeleton thus it’s a supportive structure and holds a significant position in assisting respiratory activities. Also, it is responsible for the stability of the appendicular skeleton.

  • Skull

Skull bones are 22 in number and are of two types i.e. facial bones and cranial bones. There are eight cranial bones that cover the brain and offer a ground for the head and neck muscles attachment. However, facial bones are 14 in total joined in a way to provide an opening for the eyes, nose, and mouth. Facial muscles are attached to these bones. Skull provides support to the head and face maintaining the shape. The hard covering of skull bone protects the delicate brain inside from an injury.

  • Vertebral column

The human spinal cord is a major connection between the body and the brain. It is protected by the vertebral column which we often referred as the spine or backbone. The vertebral column contains 26 bones with a hole in the center of each individual bone through which the spinal cord passes. The vertebral column of the human endoskeleton is head support and a point for the attachment of ribs. Muscles like that of the neck and back adhere to the vertebral column. The curve shape of the vertebral column enhances the strength and makes the backbone flexible enough to absorb shocks. Intervertebral discs are located between the joining points of two vertebrae. This disc is fibrous cartilage which offers a frictionless surface for joint movement, absorbs shocks, and serves as a ligament to hold vertebrae together.

  • Ribcage

A ribcage grants protection to organs such as the heart and lungs, keeping them safe inside from injury due to external blows. It’s a part of the endoskeleton comprising ribs, thoracic vertebrae, sternum and costal cartilages. A ribcage is 12 pairs of ribs, attached to thoracic vertebrae at the back and to a long flat bone called the sternum at the front. It provides stability to the shoulder and arms and offers a place for the attachment of the back, chest, neck and shoulder muscles. A diaphragm that aids in the breathing process is also attached to the ribcage.

Appendicular skeleton

The appendicular endoskeleton comprises bones of the upper limbs, lower limbs, shoulder girdle and pelvic girdle. A shoulder or pectoral girdle is a mode of attachment of upper limbs i.e. hand, forearm, and arm to the body while a pelvic girdle attaches lower limbs i.e. bones of the thigh, leg, and foot to the axial skeleton. Upper limbs help in holding and manipulating objects whereas lower limbs let us move from our place.

  • Pectoral or shoulder girdle

It comprises bones that ensure the joining of upper limbs to the body’s trunk. The collarbone and shoulder blade (scapula) is part of it. The collarbone is a horizontally positioned long bone right above the first rib of the thoracic cage. The scapula on the other hand is a flat bone in a triangular shape that supports muscles passing by the shoulder joint.

  • Upper limb

30 bones together structure the upper limb which includes the largest bone humerus running from shoulder to elbow. Radius and ulna are forearm bones joined to the humerus through the elbow then the carpal bones of the wrist, metacarpals in the hand and finally phalanges, the bones in the fingers.

  • Pelvic girdle

The pelvic girdle is attached to the axial skeleton in the most secure and strong way because lower limbs have to bear body weight and indulge in locomotion so they need to have a strong joining with the upper body. Further strength is imparted by attachment with hip bones.

  • Lower limbs

The lower limb is composed of the thighbone (femur), leg bones (fibula and tibia), the kneecap (patella), ankle bones (tarsals), and foot bones (metatarsals), and bones of the toes (phalanges). These bones of the human endoskeleton are strong and thicker in size as compared to bones of upper limbs as they have to stand upper body weight and endure force due to locomotion.

Types of bones in the human endoskeleton

The human endoskeleton consists of 206 bones, they vary in size and are shaped according to the function it performs. Type of bones that exist in the human body are:

  • Long bones

Long bones within the body assist in movement and are weight-bearing bones. Their length is larger than the width example the femur, which is the longest bone present in the human leg. However, bones in the fingers are also counted among long bones although they are relatively smaller in size, their length is longer than their width. Long bones are usually part of the appendicular skeleton i.e. bones of upper limbs such as the humerus, ulna, radius, metacarpals, and phalanges. Bones of lower limbs such as tibia, fibula, femur, metatarsals, and phalanges.

  • Flat bones

Bones like occipital, parietal, nasal, frontal, lacrimal, and vomer are flat bones present in the skull. Sternum and ribs are flat bones in the ribcage while ilium, ischium, and pubis are flat bones located in the pelvis. Their function is to secure delicate organs like the skull shielding brain, the ribcage secure heart and lungs, and the pelvis to protect pelvic organs. Due to their flat nature, these bones offer a larger surface area for muscle attachment.

  • Short bones

The width and length of short bones are almost similar and thus are cubic in shape. Short bones assist in movement and provide stability to joints like the ankle and wrist. In the wrist, these short bones are found as carpals and in the ankle as tarsals.

  • Sesamoid bones

Sesamoid bones are embedded within the tendon and strengthen them. Tendons of the knees, hands and feet are good examples of sesamoid bones. These bones are smaller in size and round in shape but work effectively to relieve stress over tendons and protect them from wear and tear. The kneecap or patella is a prominent and better example of sesamoid bones.

  • Irregular bones

As the name implies such bones are irregular in shape having a complex structure. The vertebral column is formed with the joining of small vertebrae that are irregular in shape but their function is vital in shielding the spinal cord.

Composition of bones

What our endoskeleton is made of? We are advised to intake calcium for strong bones. It is because this hard framework is made up of collagen, a protein which further harden by the deposition of calcium phosphate. Bones are a storehouse of calcium which when required by the body absorb in the bloodstream. Thus bones degenerate and then regenerate, this process keeps going throughout life which needs to be balanced through sufficient intake of calcium and vitamin D. While exploring the biological aspects of bones it is discovered that three kinds of bone cells are responsible for this phenomenon:

  • Osteoblasts

These are bone-building cells that help to strengthen the endoskeleton. Osteoblasts perform two major functions. Firstly they help release different types of proteins for bone formation and the second is a regulation of bone minerals.

  • Osteocytes

Initially, the meticulous functioning of osteocytes was unknown but with technological advancement their part in bone maintenance and development become clear. Osteocytes can trigger the working of cells covering them and can also help in osteoblast stimulation. These cells can sense, transport signals, and exchange ions to and from bones. The cell arrangement and shape support the bone mechanics.

  • Osteoclasts

Osteoclasts show very different behavior when compared with other bone cells. Their function is to absorb bone, and degenerate it so that new cells could develop. A decrease in the number of osteoclasts develops a bone disease called osteopetrosis whereas an increase in number leads to osteoporosis, a disease in which bones began to disintegrate rapidly, become weak and are more vulnerable to fracture.

The bones of a human endoskeleton are composed of two types of tissues, a hard outer layer and a soft spongy inner part. The solid outer covering is termed compact bone which is similar in appearance to ivory and is strong. Whereas the inner part is called cancellous which is sponge-like and a bit softer than the outer covering. This inner spongy part is filled with bone marrow. But not all the bones in the body have bone marrow. Only a few bones contain it which have stem cells to produce blood cells and platelets.

Health issues regarding endoskeleton

Bone construction and destruction is the natural process that keeps on going within us, this process runs in a balanced way unless some sort of disturbance is created. If the bones regenerate more than degeneration it leads to a disease called osteopetrosis and if bone absorbs faster than recreation a disease called osteoporosis overcomes in which bone density reduces and it becomes fragile enough to break easily. Arthritis is the major concern of every person nowadays. It weakens bones making them painful and limiting the range of motion.

Osteonecrosis is another bone concern where the blood supply to bone is limited leading to bone death. Pain induction and disability are its major symptoms. Bone infection also disintegrates bone health making it weak and painful. Moreover, by birth bone or inherited deformity is also an issue that needs attention and can be treated through surgery. An accidental fall, sudden hit or blow, twists, or turns are more reasons that run down the healthy endoskeleton causing fractures.

Growing age is the major factor causing bone issues which need to be balanced through a good diet, physical therapy and exercise as recommended by an orthopedist. Issues that still exist even after non-surgical methods can be addressed through surgery which gives a successful renewal of joints and bones.


The endoskeleton makes locomotion possible and conserves body shape. A little damage to bones can deprive us of routine activities, which could be frustrating. Therefore, bone health comes first. Keeping a balance between bone degeneration and regeneration is essential, take good food with sufficient calcium to safeguard your endoskeleton system.