Waldeyer’s ring is a collection of lymphoid tissue or follicles in the upper part of digestive system. This ring is formed by: Superiorly- Pharyngeal tonsils or Adenoids. Inferiorly- Lingual tonsil. Laterally- Palatine tonsils and tubal tonsils. I. Pharyngeal Tonsil: Lie postero superiorly under the mucous membrane of the roof and adjoining posterior wall of nasopharynx. II. Lingual Tonsil: This is [...]
In this article we will discuss about the meaning, parts and surfaces of frontal bone which belongs to human skull. Meaning and Parts of Frontal Bone: This is a membrane bone, forms forehead and lodges frontal air sinus, i.e., pneumatic bone. Parts: Three parts are: 1. Squamous part 2. Orbital plates are on either side 3. Nasal part. I. Squamous [...]
The human body has got several mechanisms to combat infections due to pathogenic organisms. It should be realised that many harmless organisms live in symbiosis in our body in the upper respiratory tract, in the lower bowels and in the skin. These may occasionally infect the tissues when the resistance is extremely low or viral infections have devitalised mucosal membrane. [...]