Anatomy of the viscera: Overview

Anatomy of the viscera: OverviewAnatomical features of the internal organs. Types of internal organs. Wall of the hollow organ
~ 2 min

Splanchnology is the study of internal organs.

They are located inside the cavities of the body, differ in shape and size, and perform certain functions.

Internal organs
Internal organs

According to their internal structure, the organs of the digestive system are divided into three groups:

  1. Tubular organs
  2. Parenchymal organs
  3. And organs with a specific structure

Tubular or hollow organs have a similar wall structure and contain a cavity. Such organs include:

  • Esophagus
Esophagus (oesophagus)
Esophagus (oesophagus)
  • Stomach
Stomach (gaster)
Stomach (gaster)
  • Small intestine
Small intestine (intestinum tenue)
Small intestine (intestinum tenue)
  • Large intestine
Large intestine (intestinum crassum)
Large intestine (intestinum crassum)
  • Gallbladder
Gallbladder (vesica biliaris / vesica fellea)
Gallbladder (vesica biliaris / vesica fellea)
  • Appendix
Appendix (appendix vermiformis)
Appendix (appendix vermiformis)
  • Trachea and bronchi
Trachea and bronchi (thachea et bronchi)
Trachea and bronchi (thachea et bronchi)

Parenchymal organs include:

  • Liver
Liver (hepar)
Liver (hepar)
  • Pancreas
Pancreas (pancreas)
Pancreas (pancreas)
  • Lungs
Lungs (pulmones)
Lungs (pulmones)
  • Kidneys
Kidneys (ren)
Kidneys (ren)
  • Lymph nodes
Lymph node (nodus lymphoideus)
Lymph node (nodus lymphoideus)
  • Thymus
Thymus (thymus)
Thymus (thymus)
  • Brain
Brain (encephalon)
Brain (encephalon)
  • Adrenal glands
Adrenal gland (glandula suprarenalis)
Adrenal gland (glandula suprarenalis)
  • Ovaries
Ovary (ovarium)
Ovary (ovarium)
  • Testicles
Testicle (testis)
Testicle (testis)

They are composed of a mass of the same consistency.

Only a few organs differ in the specific features of their structure. These include the:

Tongue, which is composed of a mucosal membrane and muscles

Tongue (lingua)
Tongue (lingua)

and the teeth, which are composed of hard tissues.

Teeth (dentes)
Teeth (dentes)

Each organ is described according to the following parameters:

  1. Holotopy, which is the location of an organ in a specific cavity or area of the human body. In this case, the organ is projected onto the surface of the body.
  2. Skeletotopy, which is the location of an organ in relation to certain bone structures.
  3. Syntopy, which is the location of an organ in relation to other organs.
  4. Macroscopic structure of an organ, which includes its main components, surfaces, borders, etc.
  5. Blood supply to the organ, which includes the names of the vessels through which blood flows to the organ and away from it
  6. Innervation of an organ, which includes nerves innervating an organ.
  7. Lymph outflow, which includes the main lymph nodes and lymph outflow pathways.

Parenchyma is the main tissue of organs surrounded by connective tissue called stroma.

Vessels and nerves pass through the stroma.

Structural and functional units are the smallest parts of parenchymal organs capable of performing their function, limited by a connective tissue framework with its proper vascular bed.

A segment is a macroscopically visible part of an organ that has relatively autonomous blood circulation, lymph circulation and innervation.

Tubular organs have three tunicae as part of their walls:

  1. Mucosa (tunica mucosa)
  2. Muscular layer (tunica muscularis)
  3. Adventitia (tunica adventitia)

The mucosa (tunica mucosa) lines the internal surface of hollow organs. Its description reflects the features of the epithelium. It can be either a multi-layered epithelium (of cutaneous type, as in the oral cavity) or a single-layered epithelium (as in the stomach or intestines). The nature of the folds (longitudinal, transverse) is also noted.

Mucosa (tunica mucosa)
Mucosa (tunica mucosa)

The submucosa (tela submucosas) lies on the border of the mucous and muscular membranes. If the folds of the organ are prominent, that means that the submucosa is well developed. It is structurally defined as a connective tissue in which the vascular and nerve plexuses are located. It has high mechanical strength.

Submucosa (tela submucosa)
Submucosa (tela submucosa)

The muscular coat is the middle sheath of a hollow muscular organ. In most cases, it is represented by two differently oriented layers of smooth muscle tissue.

Muscular coat (tunica muscularis)
Muscular coat (tunica muscularis)

The circular layer (stratum circulare) is located inside, directly behind the submucosa, thickens in a number of organs with the formation of sphincters.

Circular layer (stratum circulare)
Circular layer (stratum circulare)

The longitudinal layer (stratum longitudinale) lies externally.

Longitudinal layer (stratum longitudinale)
Longitudinal layer (stratum longitudinale)

The external sheath of hollow organs may be composed of:

  • Adventitia (tunica adventitia)
  • Serosa (tunica serosa)

The adventitia (tunica adventitia) is a part of organs that fuse with the surrounding tissues: pharynx, esophagus, duodenum, etc. They cannot move because they are tightly fixed to neighboring structures.

Adventitia (tunica adventitia)
Adventitia (tunica adventitia)

The serosa (tunica serosa) is a thin, transparent plate, its basis is a fibrous connective tissue covered from the outside with a layer of flat cells. It is called mesothelium. It is capable of producing and absorbing serous fluid. Serous fluid reduces friction when the shape and position of the organ changes.

Serosa (tunica serosa)
Serosa (tunica serosa)
Serosa (tunica serosa)
Serosa (tunica serosa)

Organs covered with the serous coat have some mobility and can shift.

The peritoneum (peritoneum) is the serous coat covering most of the abdominal organs.

Peritoneum (peritoneum)
Peritoneum (peritoneum)
Dictionary

Anatomy of the viscera

Digestive system
systema digestorium
Lip
labium
Oral cavity
cavitas oris
Cheeks
buccae
Tongue
lingua
Pharynx
pharynx
Esophagus
oesophagus
Stomach
ventriculus/gaster
Duodenum
duodenum
Liver
hepar
Pancreas
pancreas
Gallbladder
vesica fellea
Jejunum
jejunum
Ileum
ilium
Caecum
caecum
Vermiform appendix
appendix vermiformis
Ascending colon
colon ascendens
Transverse colon
colon transversum
Descending colon
colon descendens
Sigmoid colon
colon sigmoideum
Rectum
rectum
Internal organs
viscera/splanchna
Mucous membrane
tunica mucosa
Muscular layer
tunica muscularis
Adventitia
tunica adventitia
Submucosa
tela submucosa
Circular layer
stratum circulare
Longitudinal layer
stratum longitudinale
Peritoneum
peritoneum
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