The Body Cavities – Definition and Structure of body cavities

The Body Cavities

The place to keep vital & other organ in the body and provide them with adequate space is called body cavity. Mainly it is divided into two parts. Dorsal body cavity And Ventral body cavity.In the body four major cavity and many other cavity.like orbital cavity, nasal cavity, oral cavity.

1. Dorsal body cavity –

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

Cranial cavity

This consist 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.
  • Infriorly – 1 sphenoid & 1 Ethmoid And part of frontal temporal and occipital bones.

2. Ventral Body Cavities

The ventral body cavity is a human body cavity 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 upper part of 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
  • Infriorly – 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 oesophagus.
  • 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 body and is 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 – rectus abdominis muscles, 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 mid line and the psoas, quadratus lumborum and iliacus muscle on each side.
  • Superiorly – The diaphragm wich separates the thoracic cavity and abdominal cavity.
  • Infriorly – Continues with pelvic cavity.

Contents of The Abdominal cavity

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

  • The stomach, small intestine, maximum part of 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 caval)
  • Limph Nodes.

Pelvic cavity

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

  • Anteriorly – The pubic bones and simphysis pubis.
  • Posteriorly – The secrum and coccyx.
  • Laterally – The inominate bones (Ischium bones on each side).
  • Superiorly – The Pelvis cavity is continous with abdominal cavity.
  • Infriorly – 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 vigina towards the front.

Content of Pelvic Cavity

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

Other small cavities

Some other 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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