Free Ross & Wilson Anatomy and Physiology in Health and Illness by Anne Waugh, Allison Grant Page B

secretes clear, sticky, oily synovial fluid , which lubricates and nourishes the joints (see Ch. 16 ).

    Glands
    Glands are groups of epithelial cells that produce specialised secretions. Glands that discharge their secretion onto the epithelial surface of hollow organs, either directly or through a duct , are called exocrine glands . Exocrine glands vary considerably in size, shape and complexity as shown in Figure 3.24 . Secretions of exocrine glands include mucus, saliva, digestive juices and earwax. Figure 3.25 shows simple tubular glands of the large intestine. Other glands discharge their secretions into blood and lymph. These are called endocrine glands (ductless glands) and their secretions are hormones (see Ch. 9 ).

Figure 3.24  Exocrine glands: A. Simple glands. B. Compound (branching) glands.

Figure 3.25  Simple tubular glands in the large intestine. A stained photograph (magnified × 50).

Organisation of the body

Learning outcomes
After studying this section you should be able to:
define common anatomical terms
identify the principal bones of the axial skeleton and the appendicular skeleton
state the boundaries of the four body cavities
list the contents of the body cavities.

    This part of the chapter provides an overview of anatomical terms and the names and positions of bones. A more detailed account of the bones, muscles and joints is given in Chapter 16 .

    Anatomical terms

    The anatomical position
    This is the position assumed in all anatomical descriptions to ensure accuracy and consistency. The body is in the upright position with the head facing forward, the arms at the sides with the palms of the hands facing forward and the feet together.

    Median plane
    When the body, in the anatomical position, is divided longitudinally through the midline into right and left halves it has been divided in the median plane.

    Directional terms
    These paired terms are used to describe the location of body parts in relation to others, and are explained in Table 3.1 .
    Table 3.1  Paired directional terms used in anatomy
Directional term
Meaning
   Medial
   Structure is nearer to the midline. The heart is medial to the humerus
   Lateral
   Structure is further from the midline or at the side of the body. The humerus is lateral to the heart
   Proximal
   Nearer to a point of attachment of a limb, or origin of a body part. The femur is proximal to the fibula
   Distal
   Further from a point of attachment of a limb, or origin of a body part. The fibula is distal to the femur
   Anterior or ventral
   Part of the body being described is nearer the front of the body. The sternum is anterior to the vertebrae
   Posterior or dorsal
   Part of the body being described is nearer the back of the body. The vertebrae are posterior to the sternum
   Superior
   Structure nearer the head. The skull is superior to the scapulae
   Inferior
   Structure further from the head. The scapulae are inferior to the skull

    Regional terms
    These are used to describe parts of the body ( Fig. 3.26 ).

Figure 3.26  Regional and directional terms.

The skeleton
    The skeleton ( Fig. 3.27 ) is the bony framework of the body. It forms the cavities and fossae (depressions or hollows) that protect some structures, forms the joints and gives attachment to muscles. A detailed description of the bones is given in Chapter 16 . Table 16.1 , page 385 lists the terminology related to the skeleton.

Figure 3.27  Anterior view of the skeleton: axial skeleton – gold, appendicular skeleton – brown.
    The skeleton is described in two parts: axial and appendicular (the appendages attached to the axial skeleton).

    Axial skeleton
    The axial skeleton (axis of the body) consists of the skull, vertebral column, sternum (or breast bone) and the ribs.

    Skull
    The skull is described in two parts, the cranium , which contains the brain, and the face . It consists of a number of bones, which develop separately but