Veterinary Gross Anatomy
BY
Dr. Mohammed Beriso
.
CHAPTER 1. INTRODUCTION
1. General concept on the Anatomy
 Definition: The term anatomy has come to refer the
science that deals with the form and structure of
the animal body.
 It is originated from a Greek word, anatomy which
means cutting apart, because the ancient Greek
scientists uses dissecting instruments for their
investigation.
 In contrast to anatomy, which deals primarily with
structure, physiology is the study of the integrated
functions of the body and the functions of all its
parts including biophysical and biochemical
processes.
Branches of anatomy
1. Gross (macroscopic)anatomy. This is the study of
the form and structures of the body that can be seen
with the unaided eye
2. Developmental anatomy/Embryology: is the
study covering the period from conception (fertilization of
the egg) to birth
3. Microscopic anatomy/histology: The study of tissues
and cells that can be seen only with the aid of a
microscope
4. Applied anatomy: is one type of anatomy which deals
with operational activities of the animal body parts E.g:
surgery
5. Comparative anatomy: is a study of the structures of
various species of animals, with particular emphasis on
those characteristics that aid in classification
Branches cont…
6 Ultra structural anatomy/cytology: which
deals with portions of cells and tissues as they are
visualized with the aid of the electron
microscope.
7. Special Anatomy
It studies a single species or particular part of the
body of an animal.
8. Veterinary Anatomy
studies forms and structures of the domestic
animals.
Importance of Anatomy
It is a base for the study of other medical
courses since it gives most of the
terminologies.
Assists in clinical diagnosis and treatment.
B/se it deals with the form ,structure and
position of tissue, organs and system of the
body.
Methods of studying anatomy
1. Systemic studying type: is a common type of
studying anatomy in which the structure of the
body is studded based on body system
2. Regional/Topographic type of study: is studying
the body by dividing it into specific regions. E.g
axial and appendicular body parts.
Topographic anatomy divides the body of an animal
into four regions:
1. Head and neck
2. Thorax and forelimb
3. Abdomen and
4. pelvic region and Hind limb
2.Definition of terminologies
Topographic Terms: are descriptive terms which
are used in indicating the position and direction of
parts of the body precisely.
 Terms can be classified into two as:
Arbitrary plane
Directional terms
Arbitrary plane or Planes of anatomy
Arbitrary plane are imaginary frame of references used to
describe specific section or regions of the body
 Median plane is an imaginary plane passing through the
body so as to divide the body into equal right and left
halves.
 Sagittal plane is a plane parallel to the median plane. The
median plane is sometimes called the mid sagittal plane.
 Transverse plane is at right angles to the median plane and
divides the body into cranial and caudal segments
 Horizontal/Frontal plane is at right angles to both the
median plane and transverse planes. The horizontal plane
divides the body into dorsal (upper) and ventral (lower)
segments
Directional terms
 Like the directions, North, South, East and West, they
can be used to describe the locations of structures in
relation to other structures or locations in the body.
 They provides a common method of communication
that helps to avoid confusion when identifying
structures.
 Cranial: A directional term meaning toward the head.
Ex. the horn is cranial to the hump.
 Caudal: direction towards the tail.
Ex. Stomach is caudal to the heart
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 Rostral: relative position of the head structures
toward the muzzle.
 Ex. nasal cavity is rostral to the mouth.
 Medial: close to or toward the median plane.
 Ex. Spinal cord is medial to vertebral column
 Lateral: away from the median plane.
 Ex. lungs are lateral to the heart
 Dorsal : directed toward the back(dorsum).
 Ex. wither region is dorsal to sternum
 Ventral : directed toward the belly .
Ex. Spleen is ventral to the kidneys
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Superficial and external: implies proximity to the
skinor the surface of the body.
Deep and internal: Indicate proximity to the center of
anatomical structure.
Directional Terms more useful for extremities/limbs
 Proximal means relatively close to a given part,
usually the vertebral column, body, or center of
gravity. Ex. the knee is proximal to the foot.
 Distal means farther from the vertebral column
• E.g., The hoof is distal to the knee.
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Palmar: caudal surface of the forelimb distal to the elbow.
 Dorsal: when used to the forelimb refers to the
opposite palmar side( structures towards the front of
both limbs).
 Plantar: caudal surface of the hind limb below the
hock.
Prone refers to a position in which the dorsal aspect
of the body or any extremity is uppermost.
Pronation refers to the act of turning toward a prone
position.
Supine refers to the position in which the ventral
aspect of the body or palmar or plantar aspect of an
extremity is uppermost.
Supination refers to the act of turning toward a
supine position.
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limb median axis is called reference axis.
 Axial structures towards the reference axis.
Abaxial structures away from the reference axis.
External  superficial/ towards the skin of an animal.
Internal deep/ profundus/ away from the skin of the
limb.
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Descriptive Terms Useful in the Study of
Anatomy
3. Cell
 All living things, both plants and animals, are
constructed of small units called cells
 The simplest animals, such as the ameba, consist of a
single cell that is capable of performing all functions
commonly associated with life
 These functions include growth (increase in size),
metabolism (use of food), response to stimuli (such
as moving toward light), contraction(shortening in
one direction), and reproduction(development of new
individuals of the same species)
Cell cont…
 A typical cell consists of three main parts,
the cytoplasm, the nucleus, and the cell membrane
Structures of animal cell
Cell cont…
1. The Plasma Membrane: The thin plasma membrane
surrounds the cell, separating its contents from the
surroundings and controlling what enters and leaves the
cell.
 The plasma membrane is composed of two main
molecules, fats (phospholipids) and proteins
 The fats are arranged in a double layer with the large
protein molecules dotted about in the membrane
 Some of the protein molecules form tiny channels in
the membrane which helps to transport substances
from one side of the membrane to the other
Cell cont…
 Substances need to pass through the membrane to
enter or leave the cell and they do so in two ways
1. Require no energy i.e. they are passive transport,
which includes
A. diffusion – movement of molecules from high
concentration on one side of the cell membrane to
move across the membrane until they are present in
equal concentrations on both sides
B. Osmosis is in fact the diffusion of water across a
membrane that allows water across but not larger
molecules. This kind of membrane is called a semipermeable membrane
Cell cont…
2. Require energy i.e. they are active transport that
includes
A. Active transport - When a substance is transported
from a low concentration to a high concentration i.e. uphill
against the concentration gradient, energy has to be used.
 Active transport is also important for reabsorption of
glucose, amino acids and sodium ions from the urine
B. Phagocytosis - Phagocytosis is sometimes called “cell
eating”. It is a process that requires energy and is used by
cells to move solid particles like bacteria across the plasma
membrane.
Cell cont
Cell cont…
C. Pinocytosis - Pinocytosis or “cell drinking” is a very similar
process to phagocytosis but is used by cells to move fluids across
the plasma membrane
D. Exocytosis - is the process by means of which substances
formed in the cell are moved through the plasma membrane into
the fluid outside the cell (or extra-cellular fluid).
2. The Cytoplasm – the internal part of the cell and it includes:
 Cytosol - clear jelly-like fluid or intracellular fluid
 cell inclusions
 organelles
 microfilaments and microtubules are found
Organelles
 Organelles are the “little organs” of the cell - like the
heart, kidney and liver are the organs of the body
 They are structures with characteristic appearances and
specific “jobs” in the cell
 Most can not be seen with the light microscope and so
it was only when the electron microscope was
developed that they were discovered
 The main organelles in the cell are the ribosomes,
endoplasmic reticulum, mitochondrion, Golgi
complex and lysosomes
► Ribosomes are tiny spherical organelles that make
proteins by joining amino acids together
Organelles cont…
► Endoplasmic reticulum (ER) is a network of
membranes that form channels throughout the
cytoplasm from the nucleus to the plasma
membrane.
 Smooth ER is where the fats in the cell are
made and in some cells, where chemicals like
alcohol, pesticides and carcinogenic molecules
are inactivated.
 Rough ER has ribosomes attached to its
surface. The function of the Rough ER is
therefore to make proteins that are modified,
stored and transported by the ER
Organelles cont…
► Mitochondria are the “power stations” of the cell
 They make energy by “burning” food molecules
like glucose. This process is called cellular
respiration
 The reaction requires oxygen and produces carbon
dioxide which is a waste product
 The overall equation for cellular respiration isGlucose + oxygen = carbon dioxide + water +
energy
► Golgi apparatus - modifies and sorts the proteins
and fats made by the ER, then surrounds them in a
membrane as vesicles
Organelles cont…
► Lysosomes are large vesicles that contain digestive
enzymes. These break down bacteria and other
substances that are brought into the cell by
phagocytosis or pinocytosis
► Microfilaments & Microtubules - Threadlike
structures called microfilaments and microtubules that
can contract and relax for cell movement
 These structures also form the projections from the
plasma membrane known as flagella (singular
flagellum) as in the sperm tail, and cilia found lining
the respiratory tract and used to remove mucus that has
trapped dust particles
Organelles cont…
3. Nucleus is the largest structure in a cell and can be seen with
the light microscope
 It is a spherical or oval body that contains the chromosomes
 Nucleus controls the development and activity of the cell
 Most cells contain a nucleus although mature red blood
cells have no nucleus and muscle cells have several nuclei
 Controls the two cell divisions i.e
 Mitosis - division of somatic cells to produce two daughter
cells. division of diploid cells into 2 similar diploid cells
with each other and their mother cell
 Meiosis - division of germ cells (diploid cells) into 4
different haploid cells from its mother cells