Clinical Applications of Human Anatomy and Physiology for Healthcare Professionals. Jassin M. Jouria

refer to the bones in the vertical axis, is composed of 80 bones that include the vertebral (spinal) column, the rib cage, and the skull.15 The appendicular skeleton, named after the term appendage, is made up of the remaining 126 bones, including the bones of the shoulder girdle, the pelvic girdle, and the arms, legs, hands, and feet.16

      Figure 1-17 X-rays of skeletal bones and joints.

      Along with some auxiliary structures such as ligaments, tendons, joints, and cartilage – the skeletal system functions as a platform permitting movement, protection of organs, providing support and stability, storage of minerals such as calcium and iron, and production of red blood cells or hematopoiesis. These processes will be discussed in much greater detail in Chapter 4: The Skeletal System.

      Urinary system

      The urinary system functions as a whole to remove excess, unnecessary, and sometimes harmful substances, including toxins, fluids, and metabolic byproducts from the body through the production and excretion of urine.

      Figure 1-18 Urinary system components.

      The urinary system, also called the excretory system, is the organ system responsible for the formation, storage, and excretion of urine. In the human body, the macroscopic structures include the kidneys, ureters, bladder, and urethra. The kidneys are “bean-shaped” organs that float just beneath the ribcage in the abdominal cavity. They are retro-peritoneal, meaning they are located behind the peritoneum.

Although a relatively small structure, (each kidney is approximately four to six inches long and three inches wide), the kidneys receive anywhere from 20–25% (approximately 1200 ml of the total blood pumped from the heart each and every minute!17

      The kidney’s prime function is to filter excess fluid, toxins, and byproducts from the blood, and expel it form the body. Once urine leaves the kidneys, it is carried to the bladder by two hollow tube-like projections, called ureters. From the bladder, urine is expelled from the body via the urethra.

      Other functions of the kidneys include salt and water regulation, pH balance, medication clearance, and erythropoietin production. Several other structures play a significant role within the urinary system and will be discussed in greater detail later. Some of these structures include the glomerulus, the renal corpuscle, Bowman’s capsule, the nephron, and the renal tubules.

      The urinary system will be discussed in greater detail in Chapter 12: The Urinary System.

       ■Anatomical Terminology

      In order to avoid ambiguity and confusion, standard anatomical terminology is used universally when studying the science of any organism, and with specific regards to its anatomy. Because an organism can change position with respect to the environment, and because parts of the organism (head, arms, legs, etc.) can change position with respect to the organism’s body itself, it is fundamental that descriptive and positional terms refer to the organism when it is in standard anatomical position.

      Standard anatomical position is assumed when the body is standing erect, facing forward, feet slightly apart, with the arms resting at the sides – slightly rotated outward so that the palms face forward and the thumbs are pointed away from the body.

      While studying anatomy, one should become familiar with some of the vocabulary used to describe various aspects of the human body. Any and all directional and descriptive terms are made with reference to the body in its standard anatomical position.

      Anatomical directional terms can be used like the directions of a map to precisely communicate the positions of structures, abnormalities, and lesions of the body. This ensures a scientific method of communication that prevents incorrect and possibly life-threatening mistakes.Likewise, anatomical directional terms are also directed to cuts or sections of the body. Body planes, as they are also referred to, are a valuable way to explain and isolate distinctive views of the body.

      Some of the most universally applied anatomical directional terms are listed below, followed by body planes and sections.

      Superior – above

      Inferior – below

      Anterior/Ventral – front

      Posterior/Dorsal – back

      Medial – towards the middle/midline

      Lateral – away from the middle/midline

      Cephalad – toward the head

      Caudal – toward the tail (bone)

      Proximal – toward the trunk

      Distal – away from the trunk

      Superficial – towards the surface

      Deep – towards internal structures

      Ipsilateral – same side of the midline

      Contralateral – opposite sides of the midline

      Note: In humans, the terms “anterior” and “ventral”, as well as “posterior” and “dorsal” are interchangeable because human beings stand erect in anatomical position. Therefore, these terms become identical. Using directional terms such as “proximal” and “distal” is reserved for reference in describing the limbs.

      Let’s take a look at some specific examples:

      The head is superior to the heart.

      The leg is inferior to the thigh.

      The nose is anterior/ventral to the occipital bone.

      The tibia is medial to the fibula.

      The radius is lateral to the ulna.

      The thorax is cephalad to the umbilicus.

      The inguinal region is caudad to the umbilicus.

      The elbow is proximal to the wrist.

      The ankle is distal to the knee.

      The skin is superficial to muscle tissue.

      The bones are deep to muscle tissue.

      The spleen and left lung are ipsilateral to each other.

      The ears are contralateral to each other.

      Body planes/sections

      It is also important to become familiar with the different sections or planes of the body, as this will facilitate the study of anatomy. The first step is to imagine a series of horizontal and vertical lines passing through the body. These lines, called planes, divide the body according to their location. Three main types of planes should be noted:

      Sagittal Plane – This is an imaginary vertical line that runs from the top of the body all the down to the bottom, cutting the body into two halves, left and right. A subtype of plane that often confuses people is the distinction between a sagittal plane and a mid-sagittal plane. The only difference is that a mid-sagittal plane or cut divides the body into two equal left and right halves, whereas a sagittal plane simply divides the body into any two-unequal left and right sides.

      Frontal/Coronal Plane – This is an imaginary vertical line that runs down the epicenter of your body from one side to the other, splitting the body into a ventral (anterior) and dorsal (posterior) partition. (It helps to know and remember the location of the coronal suture in your skull, after which this plane was named.)

      Transverse Plane – This is an imaginary horizontal line cutting through the middle of your body, separating it into an upper portion and lower portion. This plane is usually the easiest to imagine, and hence remember.

      Anatomical