{"id":72,"date":"2021-12-07T05:28:17","date_gmt":"2021-12-07T05:28:17","guid":{"rendered":"https:\/\/pressbooks.publishdot.com\/anatomyphysiology\/?post_type=chapter&p=72"},"modified":"2021-12-07T05:31:52","modified_gmt":"2021-12-07T05:31:52","slug":"1-4-anatomical-terminology","status":"publish","type":"chapter","link":"https:\/\/pressbooks.publishdot.com\/anatomyphysiology\/chapter\/1-4-anatomical-terminology\/","title":{"raw":"1.4 Anatomical Terminology","rendered":"1.4 Anatomical Terminology"},"content":{"raw":"
\r\n

Learning Objectives<\/strong><\/p>\r\n\r\n<\/header>\r\n

\r\n\r\nBy the end of this section, you will be able to:\r\n
    \r\n \t
  • Demonstrate the anatomical position<\/li>\r\n \t
  • Describe the human body using directional and regional terms<\/li>\r\n \t
  • Identify three planes most commonly used in the study of anatomy<\/li>\r\n \t
  • Recognise the posterior (dorsal) and the anterior (ventral) body cavities, identifying their subdivisions and representative organs found in each<\/li>\r\n \t
  • Describe serous membranes and explain the functions<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\nAnatomists and health care providers use terminology that can be bewildering to the uninitiated. However, the purpose of this language is not to confuse, but rather to increase precision and reduce medical errors. For example, is a scar \u201cabove the wrist\u201d located on the forearm two or three inches away from the hand? Or is it at the base of the hand? Is it on the palm-side or back-side? By using precise anatomical terminology, we eliminate ambiguity. Anatomical terms derive from ancient Greek and Latin words. Because these languages are no longer used in everyday conversation, the meaning of their words does not change.\r\n\r\nAnatomical terms are made up of roots, prefixes, and suffixes. The root of a term often refers to an organ, tissue, or condition, whereas the prefix or suffix often describes the root. For example, in the disorder hypertension, the prefix \u201chyper-\u201d means \u201chigh\u201d or \u201cover,\u201d and the root word \u201ctension\u201d refers to pressure, so the word \u201chypertension\u201d refers to abnormally high blood pressure.\r\n

    Anatomical Position<\/h2>\r\nTo further increase precision, anatomists standardise the way in which they view the body. Just as maps are normally oriented with north at the top, the standard body \u201cmap,\u201d or\u00a0anatomical position<\/strong>, is that of the body standing upright, with the feet at shoulder width and parallel, toes forward. The upper limbs are held out to each side, and the palms of the hands face forward as illustrated in\u00a0Figure 1.4.1. Using this standard position reduces confusion. It does not matter how the body being described is oriented, the terms are used as if it is in anatomical position. For example, a scar in the \u201canterior (front) carpal (wrist) region\u201d would be present on the palm side of the wrist. The term \u201canterior\u201d would be used even if the hand were palm down on a table.\r\n\r\n \r\n
    \"Regions
    Figure 1.4.1<\/strong>.\u00a0Regions of the human body.<\/strong>\u00a0The human body is shown in anatomical position in an (a) anterior view and a (b) posterior view. The regions of the body are labelled in boldface.<\/figcaption><\/figure>\r\nA body that is lying down is described as either prone or supine.\u00a0Prone<\/strong>\u00a0describes a face-down orientation and\u00a0supine<\/strong>\u00a0describes a face up orientation. These terms are sometimes used in describing the position of the body during specific physical examinations or surgical procedures.\r\n

    Regional Terms<\/h2>\r\nThe human body\u2019s numerous regions have specific terms to help increase precision (see\u00a0Figure 1.4.1). Notice that the term \u201cbrachium\u201d or \u201carm\u201d is reserved for the \u201cupper arm\u201d and \u201cantebrachium\u201d or \u201cforearm\u201d is used rather than \u201clower arm.\u201d Similarly, \u201cfemur\u201d or \u201cthigh\u201d is correct, and \u201cleg\u201d or \u201ccrus\u201d is reserved for the portion of the lower limb between the knee and the ankle. You will be able to describe the body\u2019s regions using the terms from the figure.\r\n

    Directional Terms<\/h2>\r\nCertain directional anatomical terms appear throughout this and any other anatomy textbook (Figure 1.4.2). These terms are essential for describing the relative locations of different body structures. For instance, an anatomist might describe one band of tissue as \u201cinferior to\u201d another or a physician might describe a tumour as \u201csuperficial to\u201d a deeper body structure. Commit these terms to memory to avoid confusion when you are studying or describing the locations of particular body parts.\r\n\r\nAnterior<\/strong>\u00a0(or\u00a0ventral<\/strong>) Describes the front or direction toward the front of the body. The toes are anterior to the foot.\r\n\r\nPosterior<\/strong>\u00a0(or\u00a0dorsal<\/strong>) Describes the back or direction toward the back of the body. The popliteus is posterior to the patella.\r\n\r\nSuperior<\/strong>\u00a0(or\u00a0cranial<\/strong>) describes a position above or higher than another part of the body proper. The orbits are superior to the oris.\r\n\r\nInferior<\/strong>\u00a0(or\u00a0caudal<\/strong>) describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column). The pelvis is inferior to the abdomen.\r\n\r\nLateral<\/strong>\u00a0describes the side or direction toward the side of the body. The thumb (pollex) is lateral to the digits.\r\n\r\nMedial<\/strong>\u00a0describes the middle or direction toward the middle of the body. The hallux is the medial toe.\r\n\r\nProximal<\/strong>\u00a0describes a position in a limb that is nearer to the point of attachment or the trunk of the body. The brachium is proximal to the antebrachium.\r\n\r\nDistal<\/strong>\u00a0describes a position in a limb that is farther from the point of attachment or the trunk of the body. The crus is distal to the femur.\r\n\r\nSuperficial<\/strong>\u00a0describes a position closer to the surface of the body. The skin is superficial to the bones.\r\n\r\nDeep<\/strong>\u00a0describes a position farther from the surface of the body. The brain is deep to the skull.\r\n
    \"Directional
    Figure 1.4.2<\/strong>.\u00a0Directional terms applied to the human body.<\/strong>\u00a0Paired directional terms are shown as applied to the human body.<\/figcaption><\/figure>\r\n

    Body Planes<\/h2>\r\nA section is a two-dimensional surface of a three-dimensional structure that has been cut. Modern medical imaging devices enable clinicians to obtain \u201cvirtual sections\u201d of living bodies. We call these scans. Body sections and scans can be correctly interpreted, however, only if the viewer understands the plane along which the section was made. A plane is an imaginary two-dimensional surface that passes through the body. There are three planes commonly referred to in anatomy and medicine, as illustrated in\u00a0Figure 1.4.3.\r\n\r\nThe\u00a0sagittal plane<\/strong>\u00a0is the plane that divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body, it is called the midsagittal or median plane. If it divides the body into unequal right and left sides, it is called a parasagittal plane or less commonly a longitudinal section.\r\n\r\nThe\u00a0frontal plane<\/strong>\u00a0is the plane that divides the body or an organ into an anterior (front) portion and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane. (\u201cCorona\u201d is Latin for \u201ccrown.\u201d)\r\n\r\nThe\u00a0transverse plane<\/strong>\u00a0is the plane that divides the body or organ horizontally into upper and lower portions. Transverse planes produce images referred to as cross sections.\r\n
    \"Planes
    Figure 1.4.3<\/strong>.\u00a0Planes of the body.\u00a0<\/strong>The three planes most commonly used in anatomical and medical imaging are the sagittal, frontal (or coronal), and transverse plane.<\/figcaption><\/figure>\r\n

    Body Cavities and Serous Membranes<\/h2>\r\nThe body maintains its internal organisation by means of membranes, sheaths, and other structures that separate compartments. The\u00a0dorsal (posterior) cavity<\/strong>\u00a0and the\u00a0ventral (anterior) cavity<\/strong>\u00a0are the largest body compartments (Figure 1.4.4). These cavities contain and protect delicate internal organs, and the ventral cavity allows for significant changes in the size and shape of the organs as they perform their functions. The lungs, heart, stomach, and intestines, for example, can expand and contract without distorting other tissues or disrupting the activity of nearby organs.\r\n
    \"Diagram
    Figure 1.4.4<\/strong>.\u00a0Dorsal and ventral body cavities.<\/strong>\u00a0The ventral cavity includes the thoracic and abdominopelvic cavities and their subdivisions. The dorsal cavity includes the cranial and spinal cavities.<\/figcaption><\/figure>\r\n

    Subdivisions of the Posterior (Dorsal) and Anterior (Ventral) Cavities<\/h2>\r\nThe posterior (dorsal) and anterior (ventral) cavities are each subdivided into smaller cavities. In the posterior (dorsal) cavity, the\u00a0cranial cavity<\/strong>\u00a0houses the brain, and the\u00a0spinal cavity<\/strong>\u00a0(or vertebral cavity) encloses the spinal cord. Just as the brain and spinal cord make up a continuous, uninterrupted structure, the cranial and spinal cavities that house them are also continuous. The brain and spinal cord are protected by the bones of the skull and vertebral column and by cerebrospinal fluid, a colourless fluid produced by the brain, which cushions the brain and spinal cord within the posterior (dorsal) cavity.\r\n\r\nThe anterior (ventral) cavity has two main subdivisions: the thoracic cavity and the abdominopelvic cavity (see\u00a0Figure 1.4.4). The thoracic cavity is the more superior subdivision of the anterior cavity, and it is enclosed by the rib cage. The\u00a0thoracic cavity<\/strong>\u00a0contains the lungs and the heart, which is located in the mediastinum. The diaphragm forms the floor of the thoracic cavity and separates it from the more inferior abdominopelvic cavity. The\u00a0abdominopelvic cavity<\/strong>\u00a0is the largest cavity in the body. Although no membrane physically divides the abdominopelvic cavity, it can be useful to distinguish between the abdominal cavity, the division that houses the digestive organs, and the pelvic cavity, the division that houses the organs of reproduction.\r\n

    Abdominal Regions and Quadrants<\/h2>\r\nTo promote clear communication, for instance about the location of a patient\u2019s abdominal pain or a suspicious mass, health care providers typically divide up the cavity into either nine regions or four quadrants (Figure 1.4.5).\r\n
    \"Regions
    Figure 1.4.5<\/strong>.\u00a0Regions and quadrants of the peritoneal cavity<\/strong>. There are (a) nine abdominal regions and (b) four abdominal quadrants in the peritoneal cavity.<\/figcaption><\/figure>\r\nThe more detailed regional approach subdivides the cavity with one horizontal line immediately inferior to the ribs and one immediately superior to the pelvis, and two vertical lines drawn as if dropped from the midpoint of each clavicle (collarbone). There are nine resulting regions. The simpler quadrants approach, which is more commonly used in medicine, subdivides the cavity with one horizontal and one vertical line that intersect at the patient\u2019s umbilicus (navel).\r\n

    Membranes of the Anterior (Ventral) Body Cavity<\/h2>\r\nA\u00a0serous membrane<\/strong>\u00a0(also referred to a serosa) is one of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavities. The parietal layers of the membranes line the walls of the body cavity (pariet- refers to a cavity wall). The visceral layer of the membrane covers the organs (the viscera). Between the parietal and visceral layers is a very thin, fluid-filled serous space, or cavity (Figure 1.4.6).\r\n
    \"Serous
    Figure 1.4.6<\/strong>.\u00a0Serous membrane.\u00a0<\/strong>Serous membrane lines the pericardial cavity and reflects back to cover the heart\u2014much the same way that an underinflated balloon would form two layers surrounding a fist.<\/figcaption><\/figure>\r\nThere are three serous cavities and their associated membranes. The\u00a0pleura<\/strong>\u00a0is the serous membrane that surrounds the lungs in the pleural cavity; the\u00a0pericardium<\/strong>\u00a0is the serous membrane that surrounds the heart in the pericardial cavity; and the\u00a0peritoneum<\/strong>\u00a0is the serous membrane that surrounds several organs in the abdominopelvic cavity. The serous membranes form fluid-filled sacs, or cavities, that are meant to cushion and reduce friction on internal organs when they move, such as when the lungs inflate or the heart beats. Both the parietal and visceral serosa secrete the thin, slippery serous fluid located within the serous cavities. The pleural cavity reduces friction between the lungs and the body wall. Likewise, the pericardial cavity reduces friction between the heart and the wall of the pericardium. The peritoneal cavity reduces friction between the abdominal and pelvic organs and the body wall. Therefore, serous membranes provide additional protection to the viscera they enclose by reducing friction that could lead to inflammation of the organs.\r\n
    \r\n

    Section Review<\/strong><\/p>\r\n\r\n<\/header>\r\n

    \r\n\r\nAncient Greek and Latin words are used to build anatomical terms. A standard reference position for mapping the body\u2019s structures is the normal anatomical position. Regions of the body are identified using terms such as \u201coccipital\u201d that are more precise than common words and phrases such as \u201cthe back of the head.\u201d Directional terms such as anterior and posterior are essential for accurately describing the relative locations of body structures. Images of the body\u2019s interior commonly align along one of three planes: the sagittal, frontal, or transverse. The body\u2019s organs are organised in one of two main cavities\u2014dorsal (also referred to posterior) and ventral (also referred to anterior)\u2014which are further sub-divided according to the structures present in each area. The serous membranes have two layers\u2014parietal and visceral\u2014surrounding a fluid filled space. Serous membranes cover the lungs (pleural serosa), heart (pericardial serosa), and some abdominopelvic organs (peritoneal serosa).\r\n\r\n<\/div>\r\n<\/div>\r\n
    \r\n

    Review Questions<\/strong><\/p>\r\n\r\n<\/header>\r\n

    \r\n
    \r\n
    [h5p id=\"16\"]<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n
    \r\n

    Critical Thinking Questions<\/strong><\/p>\r\n\r\n<\/header>\r\n

    \r\n
    \r\n
    [h5p id=\"17\"]<\/div>\r\n<\/div>\r\n
    \r\n
    [h5p id=\"18\"]<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\nClick the drop down below to review the terms learned from this chapter.\r\n
    \r\n
    [h5p id=\"19\"]<\/div>\r\n<\/div>","rendered":"
    \n
    \n

    Learning Objectives<\/strong><\/p>\n<\/header>\n

    \n

    By the end of this section, you will be able to:<\/p>\n

      \n
    • Demonstrate the anatomical position<\/li>\n
    • Describe the human body using directional and regional terms<\/li>\n
    • Identify three planes most commonly used in the study of anatomy<\/li>\n
    • Recognise the posterior (dorsal) and the anterior (ventral) body cavities, identifying their subdivisions and representative organs found in each<\/li>\n
    • Describe serous membranes and explain the functions<\/li>\n<\/ul>\n<\/div>\n<\/div>\n

      Anatomists and health care providers use terminology that can be bewildering to the uninitiated. However, the purpose of this language is not to confuse, but rather to increase precision and reduce medical errors. For example, is a scar \u201cabove the wrist\u201d located on the forearm two or three inches away from the hand? Or is it at the base of the hand? Is it on the palm-side or back-side? By using precise anatomical terminology, we eliminate ambiguity. Anatomical terms derive from ancient Greek and Latin words. Because these languages are no longer used in everyday conversation, the meaning of their words does not change.<\/p>\n

      Anatomical terms are made up of roots, prefixes, and suffixes. The root of a term often refers to an organ, tissue, or condition, whereas the prefix or suffix often describes the root. For example, in the disorder hypertension, the prefix \u201chyper-\u201d means \u201chigh\u201d or \u201cover,\u201d and the root word \u201ctension\u201d refers to pressure, so the word \u201chypertension\u201d refers to abnormally high blood pressure.<\/p>\n

      Anatomical Position<\/h2>\n

      To further increase precision, anatomists standardise the way in which they view the body. Just as maps are normally oriented with north at the top, the standard body \u201cmap,\u201d or\u00a0anatomical position<\/strong>, is that of the body standing upright, with the feet at shoulder width and parallel, toes forward. The upper limbs are held out to each side, and the palms of the hands face forward as illustrated in\u00a0Figure 1.4.1. Using this standard position reduces confusion. It does not matter how the body being described is oriented, the terms are used as if it is in anatomical position. For example, a scar in the \u201canterior (front) carpal (wrist) region\u201d would be present on the palm side of the wrist. The term \u201canterior\u201d would be used even if the hand were palm down on a table.<\/p>\n

       <\/p>\n

      \"Regions
      Figure 1.4.1<\/strong>.\u00a0Regions of the human body.<\/strong>\u00a0The human body is shown in anatomical position in an (a) anterior view and a (b) posterior view. The regions of the body are labelled in boldface.<\/figcaption><\/figure>\n

      A body that is lying down is described as either prone or supine.\u00a0Prone<\/strong>\u00a0describes a face-down orientation and\u00a0supine<\/strong>\u00a0describes a face up orientation. These terms are sometimes used in describing the position of the body during specific physical examinations or surgical procedures.<\/p>\n

      Regional Terms<\/h2>\n

      The human body\u2019s numerous regions have specific terms to help increase precision (see\u00a0Figure 1.4.1). Notice that the term \u201cbrachium\u201d or \u201carm\u201d is reserved for the \u201cupper arm\u201d and \u201cantebrachium\u201d or \u201cforearm\u201d is used rather than \u201clower arm.\u201d Similarly, \u201cfemur\u201d or \u201cthigh\u201d is correct, and \u201cleg\u201d or \u201ccrus\u201d is reserved for the portion of the lower limb between the knee and the ankle. You will be able to describe the body\u2019s regions using the terms from the figure.<\/p>\n

      Directional Terms<\/h2>\n

      Certain directional anatomical terms appear throughout this and any other anatomy textbook (Figure 1.4.2). These terms are essential for describing the relative locations of different body structures. For instance, an anatomist might describe one band of tissue as \u201cinferior to\u201d another or a physician might describe a tumour as \u201csuperficial to\u201d a deeper body structure. Commit these terms to memory to avoid confusion when you are studying or describing the locations of particular body parts.<\/p>\n

      Anterior<\/strong>\u00a0(or\u00a0ventral<\/strong>) Describes the front or direction toward the front of the body. The toes are anterior to the foot.<\/p>\n

      Posterior<\/strong>\u00a0(or\u00a0dorsal<\/strong>) Describes the back or direction toward the back of the body. The popliteus is posterior to the patella.<\/p>\n

      Superior<\/strong>\u00a0(or\u00a0cranial<\/strong>) describes a position above or higher than another part of the body proper. The orbits are superior to the oris.<\/p>\n

      Inferior<\/strong>\u00a0(or\u00a0caudal<\/strong>) describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column). The pelvis is inferior to the abdomen.<\/p>\n

      Lateral<\/strong>\u00a0describes the side or direction toward the side of the body. The thumb (pollex) is lateral to the digits.<\/p>\n

      Medial<\/strong>\u00a0describes the middle or direction toward the middle of the body. The hallux is the medial toe.<\/p>\n

      Proximal<\/strong>\u00a0describes a position in a limb that is nearer to the point of attachment or the trunk of the body. The brachium is proximal to the antebrachium.<\/p>\n

      Distal<\/strong>\u00a0describes a position in a limb that is farther from the point of attachment or the trunk of the body. The crus is distal to the femur.<\/p>\n

      Superficial<\/strong>\u00a0describes a position closer to the surface of the body. The skin is superficial to the bones.<\/p>\n

      Deep<\/strong>\u00a0describes a position farther from the surface of the body. The brain is deep to the skull.<\/p>\n

      \"Directional
      Figure 1.4.2<\/strong>.\u00a0Directional terms applied to the human body.<\/strong>\u00a0Paired directional terms are shown as applied to the human body.<\/figcaption><\/figure>\n

      Body Planes<\/h2>\n

      A section is a two-dimensional surface of a three-dimensional structure that has been cut. Modern medical imaging devices enable clinicians to obtain \u201cvirtual sections\u201d of living bodies. We call these scans. Body sections and scans can be correctly interpreted, however, only if the viewer understands the plane along which the section was made. A plane is an imaginary two-dimensional surface that passes through the body. There are three planes commonly referred to in anatomy and medicine, as illustrated in\u00a0Figure 1.4.3.<\/p>\n

      The\u00a0sagittal plane<\/strong>\u00a0is the plane that divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body, it is called the midsagittal or median plane. If it divides the body into unequal right and left sides, it is called a parasagittal plane or less commonly a longitudinal section.<\/p>\n

      The\u00a0frontal plane<\/strong>\u00a0is the plane that divides the body or an organ into an anterior (front) portion and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane. (\u201cCorona\u201d is Latin for \u201ccrown.\u201d)<\/p>\n

      The\u00a0transverse plane<\/strong>\u00a0is the plane that divides the body or organ horizontally into upper and lower portions. Transverse planes produce images referred to as cross sections.<\/p>\n

      \"Planes
      Figure 1.4.3<\/strong>.\u00a0Planes of the body.\u00a0<\/strong>The three planes most commonly used in anatomical and medical imaging are the sagittal, frontal (or coronal), and transverse plane.<\/figcaption><\/figure>\n

      Body Cavities and Serous Membranes<\/h2>\n

      The body maintains its internal organisation by means of membranes, sheaths, and other structures that separate compartments. The\u00a0dorsal (posterior) cavity<\/strong>\u00a0and the\u00a0ventral (anterior) cavity<\/strong>\u00a0are the largest body compartments (Figure 1.4.4). These cavities contain and protect delicate internal organs, and the ventral cavity allows for significant changes in the size and shape of the organs as they perform their functions. The lungs, heart, stomach, and intestines, for example, can expand and contract without distorting other tissues or disrupting the activity of nearby organs.<\/p>\n

      \"Diagram
      Figure 1.4.4<\/strong>.\u00a0Dorsal and ventral body cavities.<\/strong>\u00a0The ventral cavity includes the thoracic and abdominopelvic cavities and their subdivisions. The dorsal cavity includes the cranial and spinal cavities.<\/figcaption><\/figure>\n

      Subdivisions of the Posterior (Dorsal) and Anterior (Ventral) Cavities<\/h2>\n

      The posterior (dorsal) and anterior (ventral) cavities are each subdivided into smaller cavities. In the posterior (dorsal) cavity, the\u00a0cranial cavity<\/strong>\u00a0houses the brain, and the\u00a0spinal cavity<\/strong>\u00a0(or vertebral cavity) encloses the spinal cord. Just as the brain and spinal cord make up a continuous, uninterrupted structure, the cranial and spinal cavities that house them are also continuous. The brain and spinal cord are protected by the bones of the skull and vertebral column and by cerebrospinal fluid, a colourless fluid produced by the brain, which cushions the brain and spinal cord within the posterior (dorsal) cavity.<\/p>\n

      The anterior (ventral) cavity has two main subdivisions: the thoracic cavity and the abdominopelvic cavity (see\u00a0Figure 1.4.4). The thoracic cavity is the more superior subdivision of the anterior cavity, and it is enclosed by the rib cage. The\u00a0thoracic cavity<\/strong>\u00a0contains the lungs and the heart, which is located in the mediastinum. The diaphragm forms the floor of the thoracic cavity and separates it from the more inferior abdominopelvic cavity. The\u00a0abdominopelvic cavity<\/strong>\u00a0is the largest cavity in the body. Although no membrane physically divides the abdominopelvic cavity, it can be useful to distinguish between the abdominal cavity, the division that houses the digestive organs, and the pelvic cavity, the division that houses the organs of reproduction.<\/p>\n

      Abdominal Regions and Quadrants<\/h2>\n

      To promote clear communication, for instance about the location of a patient\u2019s abdominal pain or a suspicious mass, health care providers typically divide up the cavity into either nine regions or four quadrants (Figure 1.4.5).<\/p>\n

      \"Regions
      Figure 1.4.5<\/strong>.\u00a0Regions and quadrants of the peritoneal cavity<\/strong>. There are (a) nine abdominal regions and (b) four abdominal quadrants in the peritoneal cavity.<\/figcaption><\/figure>\n

      The more detailed regional approach subdivides the cavity with one horizontal line immediately inferior to the ribs and one immediately superior to the pelvis, and two vertical lines drawn as if dropped from the midpoint of each clavicle (collarbone). There are nine resulting regions. The simpler quadrants approach, which is more commonly used in medicine, subdivides the cavity with one horizontal and one vertical line that intersect at the patient\u2019s umbilicus (navel).<\/p>\n

      Membranes of the Anterior (Ventral) Body Cavity<\/h2>\n

      A\u00a0serous membrane<\/strong>\u00a0(also referred to a serosa) is one of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavities. The parietal layers of the membranes line the walls of the body cavity (pariet- refers to a cavity wall). The visceral layer of the membrane covers the organs (the viscera). Between the parietal and visceral layers is a very thin, fluid-filled serous space, or cavity (Figure 1.4.6).<\/p>\n

      \"Serous
      Figure 1.4.6<\/strong>.\u00a0Serous membrane.\u00a0<\/strong>Serous membrane lines the pericardial cavity and reflects back to cover the heart\u2014much the same way that an underinflated balloon would form two layers surrounding a fist.<\/figcaption><\/figure>\n

      There are three serous cavities and their associated membranes. The\u00a0pleura<\/strong>\u00a0is the serous membrane that surrounds the lungs in the pleural cavity; the\u00a0pericardium<\/strong>\u00a0is the serous membrane that surrounds the heart in the pericardial cavity; and the\u00a0peritoneum<\/strong>\u00a0is the serous membrane that surrounds several organs in the abdominopelvic cavity. The serous membranes form fluid-filled sacs, or cavities, that are meant to cushion and reduce friction on internal organs when they move, such as when the lungs inflate or the heart beats. Both the parietal and visceral serosa secrete the thin, slippery serous fluid located within the serous cavities. The pleural cavity reduces friction between the lungs and the body wall. Likewise, the pericardial cavity reduces friction between the heart and the wall of the pericardium. The peritoneal cavity reduces friction between the abdominal and pelvic organs and the body wall. Therefore, serous membranes provide additional protection to the viscera they enclose by reducing friction that could lead to inflammation of the organs.<\/p>\n

      \n
      \n

      Section Review<\/strong><\/p>\n<\/header>\n

      \n

      Ancient Greek and Latin words are used to build anatomical terms. A standard reference position for mapping the body\u2019s structures is the normal anatomical position. Regions of the body are identified using terms such as \u201coccipital\u201d that are more precise than common words and phrases such as \u201cthe back of the head.\u201d Directional terms such as anterior and posterior are essential for accurately describing the relative locations of body structures. Images of the body\u2019s interior commonly align along one of three planes: the sagittal, frontal, or transverse. The body\u2019s organs are organised in one of two main cavities\u2014dorsal (also referred to posterior) and ventral (also referred to anterior)\u2014which are further sub-divided according to the structures present in each area. The serous membranes have two layers\u2014parietal and visceral\u2014surrounding a fluid filled space. Serous membranes cover the lungs (pleural serosa), heart (pericardial serosa), and some abdominopelvic organs (peritoneal serosa).<\/p>\n<\/div>\n<\/div>\n

      \n
      \n

      Review Questions<\/strong><\/p>\n<\/header>\n

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