Introduction to the Human Body: Body Cavities
Introduction:
Human beings are the most complex of all the living organisms.
Human body contains many organs which work in an organized manner for an efficient working of the human body.
The study of human body is divided broadly in two divisions,
Anatomy
Physiology.
Human Anatomy is the branch of science that deals with the study of structures of different body parts.
Human Physiology is the branch of science that deals with the study of functions of different body parts.
Human Anatomy: Study of Structure.
Human Physiology: Study Of Functions.
Body Cavities:
These are spaces in the body that protect, separate and support the internal organs of the body.
The body cavities are mainly divided into two types,
Dorsal Body Cavities.
Ventral Body Cavities.
Dorsal Body Cavities:
They are present on the dorsal side of the body.
They are comparatively smaller as compared to the ventral body cavities.
They are classified as,
Cranial Cavity.
Vertebral Cavity.
Cranial Cavity:
It contains Brain.
Boundaries are formed by the bones of the skull (Fig. 1.1):
Anteriorly —1 frontal bone
Laterally — 2 temporal bones
Posteriorly — I occipital bone
Superiorly — 2 parietal bones
Inferiorly — I sphenoid and 1 ethmoid bone and parts of the frontal, temporal and occipital bones.
Fig. 1.1
Vertebral Cavity:
It contains “Spinal Cord.”
Boundaries:
Are made by bones of the vertebral column i.e. by vertebrae and the intervertebral discs between the bodies of the vertebrae.
Ventral Body Cavities:
They are present on the ventral side of the body.
They are much larger in size as compared to the dorsal body cavities.
They are further classified as followings,
Thoracic Cavity
Abdominal Cavity.
Pelvic Cavity.
Thoracic Cavity:
It is formed by,
Anteriorly — the sternum and costal cartilages of the ribs
Laterally — 12 pairs of ribs and the intercostal muscles
Posteriorly — the thoracic vertebrae and the intervertebral discs between the bodies of the vertebrae.
Superiorly — the structures forming the root of the neck
Inferiorly — the diaphragm, a dome-shaped muscle.
Contents
The main organs and structures contained in the thoracic cavities are (Fig. 1.2):
the trachea,
2 bronchi,
2 lungs
the heart,
aorta,
superior and inferior vena cava,
numerous other blood vessels
the oesophagus
Fig. 1.2
The thoracic cavity is divided into three parts,
Pleural Cavity: One around each lungs, Contains fluid.
Pericardial Cavity: Around heart, Contains fluid.
Mediastinum: Central part extends from sternum to vertebral column and from first rib to diaphragm, contains all organs of thoracic cavity except lungs.
Abdominal Cavity:
This is the largest cavity in the body and is oval in shape (Fig 1.3).
It is situated in the main part of the trunk and its boundaries are:
Superiorly — the diaphragm, which separates it from the thoracic cavity
Anteriorly — the muscles forming the anterior abdominal wall
Posteriorly —the lumbar vertebrae and muscles forming the posterior abdominal wall
Laterally — the lower ribs and parts of the muscles of the abdominal wall
Inferiorly — the pelvic cavity with which it is continuous.
Fig 1.3
The abdominal cavity is divided into the nine regions shown in Figure 1.4.
Figure 1.4
Contents
the stomach,
small intestine and most of the large intestine
the liver, gallbladder, bile ducts and pancreas.
the spleen
2 kidneys and the upper part of the ureters
2 adrenal (suprarenal) glands
numerous blood vessels
lymph vessels,
nerves
lymph nodes.
Pelvic Cavity:
The pelvic cavity is roughly funnel shaped and extends from the lower end of the abdominal cavity (Fig 1.4).
The boundaries are:
Superiorly — it is continuous with the abdominal cavity
Anteriorly — the pubic bones
Posteriorly — the sacrum and coccyx
Laterally — the innominate bones
Inferiorly — the muscles of the pelvic floor.
Fig 1.4
The pelvic cavity contains the following structures:
sigmoid colon, rectum and anus
some loops of the small intestine
urinary bladder, lower parts of the ureters and the urethra
in the female, the organs of the reproductive system: the uterus, uterine tubes, ovaries and vagina.
in the male, some of the organs of the reproductive system: the prostate gland, seminal vesicles, spermatic cords, deferent ducts (vas deferens), ejaculatory ducts and the urethra.
Commonly Asked Questions:
Enlist different body cavities along with their locations.
Write in short about,
Thoracic Cavity.
Abdominal Cavity.
Pelvic Cavity.