The Human Body: An Orientation Part B Flashcards
Anatomical Position
Definition: The standard reference position used in anatomy to describe body parts and their locations.
Characteristics of Anatomical Position:
Body is erect.
Feet are slightly apart.
Palms face forward.
Thumbs point away from the body.
Orientation and Directional Terms
Superior (cranial):
Definition: Toward the head end or upper part of a structure or the body; above.
Example: The head is superior to the abdomen.
Inferior (caudal):
Definition: Away from the head end or toward the lower part of a structure or the body; below.
Example: The navel is inferior to the chin.
Anterior (ventral):
Definition: Toward or at the front of the body; in front of.
Example: The breastbone is anterior to the spine.
Comparative Note: While the terms ventral and anterior are synonymous in humans, this is not the case in four-legged animals. "Ventral" specifically refers to the "belly" of a vertebrate animal, which is the inferior surface of four-legged animals.
Posterior (dorsal):
Definition: Toward or at the back of the body; behind.
Example: The heart is posterior to the breastbone.
Comparative Note: Although dorsal and posterior surfaces are the same in humans, "dorsal" specifically refers to an animal's back. In four-legged animals, the dorsal surface is the superior surface.
Medial:
Definition: Toward or at the midline of the body; on the inner side of.
Example: The heart is medial to the arm.
Lateral:
Definition: Away from the midline of the body; on the outer side of.
Example: The arms are lateral to the chest.
Intermediate:
Definition: Between a more medial and a more lateral structure.
Example: The collarbone is intermediate between the breastbone and shoulder.
Proximal:
Definition: Closer to the origin of the body part or the point of attachment of a limb to the body trunk.
Example: The elbow is proximal to the wrist.
Distal:
Definition: Farther from the origin of a body part or the point of attachment of a limb to the body trunk.
Example: The knee is distal to the thigh.
Superficial (external):
Definition: Toward or at the body surface.
Example: The skin is superficial to the skeletal muscles.
Deep (internal):
Definition: Away from the body surface; more internal.
Example: The lungs are deep to the skin.
Regional Terms and Subdivisions
Primary Subdivisions:
Axial: Includes the head, neck, and trunk.
Appendicular: Includes the appendages or limbs.
Posterior Regional Terminology:
Cephalic (head): Includes the Otic (ear) and Occipital (back of head or base of skull) regions.
Upper extremity: Includes the Acromial (point of shoulder), Brachial (arm), and Olecranal (back of elbow) regions.
Manus (hand): Refers to the hand region.
Dorsum or dorsal (back): Includes the Scapular (shoulder blade), Vertebral (spinal column), Lumbar (loin), and Sacral (between hips) regions.
Gluteal: The buttock region.
Perineal: The region situated between the anus and the external genitalia.
Lower extremity: Includes the Femoral (thigh), Popliteal (back of knee), Sural (calf), Calcaneal (heel), and Plantar (sole) regions.
Body Planes and Sections
Sagittal Plane: Divides the body into right and left parts.
Midsagittal (Median) Plane: A sagittal plane that lies exactly on the midline.
Frontal (Coronal) Plane: Divides the body into anterior (front) and posterior (back) parts.
Transverse (Horizontal) Plane: Also known as a cross section; it divides the body into superior (upper) and inferior (lower) parts.
Oblique Section: Specific cuts made diagonally between the horizontal and vertical planes.
Anatomical Variability
Standard Accuracy: Over of all anatomical structures match textbook descriptions.
Typical Variations:
Nerves or blood vessels may be slightly out of place.
Small muscles may be entirely missing in some individuals.
Rarity: Extreme anatomical variations are seldom encountered.
Body Cavities
Dorsal Cavity: Protects the nervous system; divided into two subdivisions:
Cranial cavity: Located within the skull and encases the brain.
Vertebral cavity: Runs within the vertebral column and encases the spinal cord.
Ventral Cavity: Houses internal organs (viscera); divided into two main subdivisions:
Thoracic Cavity: Further subdivided into:
Pleural cavities: Each housing a lung.
Mediastinum: Contains the pericardial cavity and surrounds remaining thoracic organs.
Pericardial cavity: Specifically encloses the heart.
Abdominopelvic Cavity: Separated from the superior thoracic cavity by the dome-shaped diaphragm. It consists of:
Abdominal cavity: Contains the stomach, intestines, spleen, liver, and other organs.
Pelvic cavity: Located within the pelvis; contains the bladder, reproductive organs, and rectum.
Ventral Body Cavity Membranes
Parietal Serosa: Lines the internal body walls.
Visceral Serosa: Covers the external surfaces of internal organs.
Serous Fluid: A lubricating fluid that separates the parietal and visceral serosae to reduce friction.
Specific Example (The Heart):
The heart is surrounded by the parietal pericardium (outer wall), the pericardial space containing serous fluid, and the visceral pericardium (inner wall directly covering the heart).
Other Body Cavities
Oral and Digestive: The mouth and the cavities of the digestive organs.
Nasal: Located within and posterior to the nose.
Orbital: Cavities that house the eyes.
Middle Ear: Contain the ossicles (small bones) that transmit sound vibrations.
Synovial: Joint cavities.
Abdominopelvic Regions and Quadrants
Nine Abdominopelvic Regions:
Umbilical Region: The centermost region.
Epigastric Region: Located superior to the umbilical region.
Hypogastric (Pubic) Region: Located inferior to the umbilical region.
Right and Left Iliac (Inguinal) Regions: Located lateral to the hypogastric region.
Right and Left Lumbar Regions: Located lateral to the umbilical region.
Right and Left Hypochondriac Regions: Located lateral to the epigastric region.
Internal Organs of the Abdominopelvic Regions:
Liver and Gallbladder: Found primarily in the right hypochondriac and epigastric regions.
Stomach: Found in the epigastric and left hypochondriac regions.
Large Intestine: Includes the ascending colon, transverse colon, descending colon, and cecum.
Small Intestine: Occupies most of the central and lower regions.
Urinary Bladder: Located in the hypogastric region.
Appendix: Located in the right iliac region.
Abdominopelvic Quadrants:
Right Upper Quadrant (RUQ)
Left Upper Quadrant (LUQ)
Right Lower Quadrant (RLQ)
Left Lower Quadrant (LLQ)