Anatomy

Body Cavities

Anatomists typically divide the body into two membrane-lined internal cavities that protect the organs within them, each having 2 major subdivisions.

• Dorsal body cavity

– Part of the axial portion of the body, encased in bony structures for protection

– Houses the fragile nervous systems organs

– Includes:

• Cranial cavity: holds the

brain (encased by the skull)

• Vertebral (Spinal) cavity: holds the spinal cord within the bony vertebrae

Body Cavities

Anatomists typically divide the body into two membrane-lined internal cavities that protect the organs within them, each having 2 major subdivisions.

• Ventral body cavity

– Part of the axial portion of the body, less protected but allows more mobility

– Houses the visceral organs

– Includes:

• Thoracic cavity: holds the heart and lungs (protected by ribs and chest muscles)

– Pleural cavities: hold the lungs

– Pericardial cavity (within the mediastinum): holds the heart, esophagus, and trachea

• Abdominopelvic cavity: holds the abdomen and pelvis

Body Cavities

A bit more about the abdominopelvic cavity

• Abdominopelvic cavity: holds the abdomen and pelvis

– Abdominal cavity: holds the stomach, intestines,

spleen, liver (as well as other organs)

– Pelvic cavity: holds the bladder, some reproductive organs, and rectum (protected by the pelvis)

Often divided into 4 quadrants

Other Body Cavities

• These other body cavities are much smaller and many have external openings.

– Oral cavity: contains the mouth, including the teeth and tongue

– Digestive cavity: connects the oral cavity all the way to the rectum

– Nasal cavity: within and behind the nose

– Orbital cavities: hold the eyes

– Middle ear cavities: contain tiny bones medial to the eardrums

– Synovial cavities: joint cavities

Body Membranes

• Body membranes line body cavities and cover the organs within them.

– Cutaneous membrane: your skin, which covers your body’s surface

• The only dry membrane!

– Mucous membranes (Mucosae): line all body cavities that open to the outside of the body

• Ex. Nasal cavity, mouth, etc.

– Serous membrane (Serosa): lines ventral body cavities that are closed, as well as covering many organs

• Parietal membrane: lines the body cavity

• Visceral membrane: covers the internal organs

• These serous membranes are separated by serous fluid

– Meninges: the membrane that covers the brain and spinal cord in the dorsal body cavity