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Mediastinum in Anatomy

Mediastinum, the anatomic region located between the lungs contains all the principal tissues and organs of the chest except the lungs. It extends from the sternum, or breastbone, back to the spinal column and is bounded laterally by the pericardium, the membrane enclosing the guts, and therefore the mediastinal pleura, membranes that are continuous with those lining the thoracic cage. The mediastinum may be a division of the thoracic cavity; it contains the guts, thymus, portions of the oesophagus and trachea, and other structures. For clinical purposes, it's traditionally divided into the anterior, middle, posterior, and superior regions.

One of the very first structures which may be observed when the external structure of the guts is viewed is that the pericardium.


The human heart is placed to the left of the chest and is filled within a fluid-filled cavity described as the pericardial cavity. The walls and lining of the pericardial space are made from a membrane referred to as the pericardium.

The pericardium may be a fibre membrane found as an external covering around the heart. It protects the heart by producing a serous fluid, which serves to lubricate the heart and stop the friction between the encompassing organs. The pericardium also helps by holding the heart in its position and by maintaining a cavity for the heart to expand itself when it's full. The pericardium has two exclusive layers-

  • Visceral Layer: It directly covers the surface of the heart.

  • Parietal Layer: It forms a sac around the outer region of the heart that contains the fluid within the pericardial space. 

Structure of the Heart Wall

The heart wall is formed from 3 layers, namely:

  • Epicardium – Epicardium is that the outermost layer of the guts. It is composed of a thin-layered membrane that serves to lubricate and protect the outer section.

  • Myocardium – this is often a layer of muscle tissue, and it constitutes the centre layer wall of the heart. It contributes to the thickness and is liable for the pumping action.

  • Endocardium – it's the innermost layer that lines the inner heart chambers and covers the guts valves.

Function of Heart

The function of the heart in any organism is to take care of a continuing flow of blood throughout the body. This replenishes oxygen and circulates nutrients among the cells and tissues. Also, because the human heart may be a homologous organ, it functions no differently from the other vertebrates that possess a heart. Following are the main functions of the heart:

  • One of the first functions of the human heart is to pump blood throughout the body.

  • Blood delivers oxygen, hormones, glucose and other components to varied parts of the body, including the human heart.

  • The heart also ensures that adequate vital sign is maintained within the body

  • There are two sorts of circulation within the body, namely circulation and circulation.

Human Respiratory System

The different human respiratory system parts that play different roles. The different parts of the respiratory system anatomy are explained below along with their functions.

1. Nose

It is one of the important respiratory system organs that possess two exterior nostrils divided by septum. The Septum is a cartilaginous structure that divides the left nostril from the right nostril.  Numerous tiny hair follicles are present that cover the interior nostril’s lining and thus act as the body’s first line of defence against foreign bodies (pathogens). The hair also provides humidity for inhaled air.

2. Larynx

Also known as the voice box or Adam’s apple, it is situated in the top of the neck facilitating the action of breathing. It is in the form of two cartilaginous chords and is located at the point of conjuction between the pharynx and trachea. It acts by rising or falling during the swallowing process and generates sound when air passes through the hollow portion in the middle. It also protects the trachea against food aspiration.

3. Pharynx

It is the part of the throat present behind the nasal cavity and the mouth, and above the larynx and oesophagus. It is a wide hollow space and a common path for air and food. It doesn’t allow the food particles entry into the windpipe. There is elastic cartilage between the oesophagus and the larynx that acts as a switch to allow the passage of air into the airway to the lungs and food into the gastrointestinal tract.

4. Trachea

It is the windpipe which is a tubular structure of about 4 inches long and half an inch in diameter. This airway system carries oxygen-rich air to the lungs. It begins under the larynx and runs down the neck through the breastbone or sternum. Its outer walls consist of C-shaped rings which are cartilaginous and provide hardness to it and can also expand completely. The trachea divides into smaller tubes called bronchi. 

5. Bronchi

The trachea splits into smaller tubes called bronchi which is the main passageway into the lungs. It is further divided into secondary and tertiary bronchioles and then again into small air-sacs known as alveoli. Alveoli are minute air sacs with thin walls that enable the exchange of gases into or away from the bloodstream.

6. Lungs

It is the spongy air-filled chief organ of the respiratory system anatomy in humans and other vertebrates. Located in the thoracic cavity of the chest on either side of the heart, they are present as a pair and help in exchanging gases between the bloodstream and the air. The right lung appears to be heavier and bigger than the left lung.

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FAQs on Mediastinum

1. What is the Human Respiratory Tract Composed of?

Ans - It is made up of the nasal chamber, nostril, larynx, pharynx, trachea, epiglottis, bronchioles, alveoli, bronchi, and lungs. Epiglottis is a flap-like structure covering the glottis and prevents the entry of food into the windpipe. The other parts of the human respiratory system are vital for the inhalation of oxygen and exhalation of carbon dioxide.

2. What are the Respiratory System Organs that Enable us to Inhale and Exhale?

Ans - Different parts of the respiratory system that are responsible to undertake the exchange of gases like oxygen and carbon dioxide include nasal cavity, oral cavity, larynx, 

pharynx, trachea, epiglottis, bronchi, bronchioles, and lungs.