Anatomy, Skeletal System

Body Cavity – Definition and Structure

Dorsal body cavity and ventral body cavity

The Body Cavities:- The place to keep vital & other organs in the body and provide them with adequate space is called a cavity. Mainly it is divided into two parts. Dorsal body cavity and ventral body cavity. Four major cavities in the body are the cranial, thoracic, abdominal, pelvic. And many others such as orbital, nasal, oral.

1. Dorsal body cavity –

Dorsal body cavity protects manly nervous system organs in the cranial cavity protect brain and its associate organs(cranial nerves) other division spinal (vertebral) cavity protect the spinal cord (spinal nerves). Other cavities – Orbital Cavity protects the eye. Nasal Cavity it’s part of the respiratory system located nostrils to the pharynx. Oral cavity part of the digestive system called the buccal cavity, mouth cavity beginning of the alimentary canal which leads to the pharynx and to the esophagus. In this cavity, Cranial is a major cavity.

Cranial cavity

This consists of the cranium which protects the brain and its boundaries are formed by the bones of the skull.

  • Anteriorly – 1 Frontal Bone.
  • Laterally – 2 Temporal Bones.
  • Posteriorly – 1 Occipital Bone.
  • Superiorly – 2 Parietal Bones.
  • Inferiorly – 1 sphenoid & 1 Ethmoid And part of frontal-temporal and occipital bones.

2. Ventral Body Cavities

The ventral cavity is a human body cavity that is made up of the superior thoracic cavity and the inferior abdominopelvic cavity. A diaphragm physically separates the two cavities the thoracic cavity contains respiratory organs lungs tracheae etc. circulatory organ heart and major blood vessels. The abdominal cavity contains digestive organs stomach liver pancreas gall bladder intestine etc, the pelvic cavity contains the urinary bladder, internal reproductive organs, and rectum.

Thoracic Cavity

This is important cavity is situated in the upper part of the trunk and its wall (boundaries) are formed by a bony framework and supporting various muscles.

  • Anteriorly – Sternum and costal cartilages and ribs
  • Laterally – Ribs 12 pairs and intercostal muscles
  • Posteriorly – The Thoracic vertebrae
  • Superiorly – The root of the neck with its muscles and blood vessels
  • Inferiorly – The Diaphragm A large dome -shape muscle. diaphragm physically separates the thoracic and abdominal cavity.

Contents of the Thoracic Cavity –

  • The Trachea, 2 bronchi, 2 lungs. Lungs occupy the greater part of the thoracic cavity.
  • The heart, aorta, superior and inferior vena cava, And other blood vessels.
  • The esophagus.
  • Thymus gland.
  • Lymph vessels and lymph nodes
  • And some impotent nerves the phrenic and vagus nerve.

Abdominal Cavity

The abdominal cavity is the largest cavity in the human (Ventral) body and is an oval shape. by convention, the abdominal cavity divided into the nine regions.

  • Anteriorly – The front of the abdominal cavity is the abdominal muscles. These muscles are – The rectus abdominis muscles known as (abdominal muscle), transversus abdominis muscle, and internal oblique muscle.
  • Laterally – The lower floating ribs and part of abdominal wall muscles.
  • Posteriorly – The lumbar Vertebral column in the midline and the psoas, quadratus lumborum, and iliacus muscle on each side.
  • Superiorly – The diaphragm which separates the thoracic cavity and abdominal cavity.
  • Inferiorly – Continues with the pelvic cavity.

Contents of The Abdominal cavity

Most of the abdominal cavity is occupied by the digestive system organs, glands and upper part of the urinary system . these are –

  • The stomach, small intestine, maximum part of the large intestine.
  • The liver, gall bladder, pancreas, and bile ducts.
  • The spline
  • Adrenal glands (Suprarenal) – 2
  • Kidney and upper part of ureters -2
  • Major blood vessels (Abdominal aorta, Inferior vena cava)
  • Lymph Nodes.

Pelvic cavity

The pelvic body cavity is roughly funnel-shaped and extends from the lower and of the abdominal cavity. The boundaries are –

  • Anteriorly – The pubic bones and the symphysis pubis.
  • Posteriorly – The sacrum and coccyx.
  • Laterally – The innominate bones (Ischium bones on each side).
  • Superiorly – The Pelvis cavity is continuous with the abdominal cavity.
  • Inferiorly – The muscles of the pelvic floor. Through the pelvic floor pass the lower part of the bowel (rectum) in the hollo formed by the sacrum behind, the urethra, and in the female vagina towards the front.

Content of Pelvic Cavity

  • The lower part of the large intestine (Sigmoid colon, Rectum, and Anus)
  • The lower part of ureters, Urinary bladder, and urethra
  • Reproductive system organs in female – uterus, uterine tubes and ovaries vagina, etc.
  • Reproductive system organs in male – Prostate gland, seminal vesicles, spermatic cords, different (vas deferens ) ducts, ejaculatory ducts, and urethra (the urethra is common in reproductive and urinary system).

Other small body cavity

Some others like Synovial cavities are small cavities. The Synovial cavities surround freely movable joints and secrete a lubricating fluid-like serous membranes

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