ANATOMY AND PHYSIOLOGY NOTES FOR YEAR 1 slide one.pptx
1. 0841 451 03/A: ANIMALANATOMY AND
PHYSIOLOGY I
BY : STEVE
General Objective
To give basic knowledge on the anatomical structure and functioning of the animal body.
1. Introduction 3 hrs
By the end of this topic the trainee should be able to:
a) Define Veterinary Anatomy, Physiology, Histology, embryology, and cytology.
b) List the branches of anatomy including gross, histology embryology and cytology
c) Explain the descriptive terms used in Anatomy- Positional, displacement and Directional terms
d) Define Cell, tissue, organ, system
e) Describe the cell structure and explain the functions of the cell organelles.
f) List the primary types of tissues, their functions and locations in the body system- epithelia,
connective tissue, muscles, nervous tissue
g) Describe the different types of tissues -epithelia, connective tissue, muscles, nervous tissue and
explain their histology 1
2. 2. Osteology and Arthrology 4 hrs
• By the end of this topic the trainee should be able to:
a)Define osteology
b)List the types and parts of the skeleton
c)State the functions of bones
d)Classify bones and give examples
e)Illustrate the gross structure of a long bone
f) Define arthrology
g)List the joints of the animal body
h)Classify joints (structural &functional) and give examples
i) Describe a synovial joint and a simple joint
2
3. 3 Myology 5 hrs
• By the end of this topic the trainee should be able to:
a) Define myology
b)State the functions of muscles
c) Classify muscles - skeletal, smooth, cardiac
d)Explain the structural difference of muscles - skeletal, smooth, cardiac
e) Define flexors, extensors, abductors, adductors, and sphincters.
f) Name the muscles of the following groups- gluteal, abdominal, respiratory,
masticatory, neck, thigh, shoulder, sphincter muscles.
g)State the function of the groups of muscles; gluteal, thigh, shoulder, brachial,
abdominal, respiratory, neck, masticatory, cutaneous and sphincter muscles.
3
4. 4. The Integumentary System 4 hrs
•By the end of this topic the trainee should be able to:
a)Define the term integumentary
b)State the functions of the integumentary system
c)Illustrate the structure of the skin
d)Illustrate the structure and the functions of the following
appendages- horn, hoof, claws, hairs and fur.
e)Illustrate the structure of the mammary gland
f)Explain the function of the mammary gland.
4
5. 5. Respiratory and Circulatory Systems
5.1 Respiratory system 4 hrs
• By the end of this topic the trainee should be able to:
i. List the parts of the respiratory system.
ii. Describe the structures of the respiratory system (Nostrils, pharynx, trachea,
Bronchi, bronchioles, alveoli.)
iii.Describe the division of respiratory system (Upper respiratory system, Lower
respiratory system)
iv.Describe the histology of the lungs in relation to gaseous exchange.
v. Explain the physiological process of respiration, - external/ internal
respiration, gaseous exchange, blood gas transport, inspiration and expiration
vi.Define the following terms used in respiration-Total lung capacity, Vital
capacity, Tidal volume.
5
6. 5.2 Circulatory system 4 hrs
• By the end of this topic the trainee should be able to:
a) List the parts of the cardiovascular system- Heart, Arteries, Veins and
Capillaries,
b)Describe the structures of the cardiovascular system.
c) State the functions of the cardiovascular system.
d)Name the components of blood (plasma proteins, blood cells and serum)
e) State the sites for the formation of blood cells.
f) State the function of plasma proteins, blood cells and serum.
g)Define blood clotting/coagulation
h)Name the factors that cause blood clotting/coagulation.
i) Name the factors that delay or prevent blood clotting.
6
7. 5.3 Lymphatic system: 1hr
• By the end of this topic the trainee should be able to:
a) List the parts of the lymphatic system. Lymph, lymphatic vessels and
Lymphoid tissues (bone marrow, lymph nodes, tonsils , thymus, bursa of
fabricius spleen)
b)State the functions of the lymphatic system.
c) List the superficial lymph nodes in domestic animals.
7
8. • 6 Female Reproductive system 5hrs
• By the end of this topic the trainee should be able to:
a) List the parts and functions of the female reproductive system: ovaries,
fallopian tube, uterus, vagina, and vulva.
b)Illustrate the structures of the female reproductive system
c) Define and explain the function of the following- ovarian follicles, placenta,
corpus luteum, endometrium,
d)Explain the following physiological processes- Oogenesis, oestrus cycle,
fertilization, implantation, pregnancy, proestral, metestral and post-estral
bleeding
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9. 7. Practical 15hrs
• By the end of these sessions the trainee should be able to:
a) Identify both gross and microscopic structures of various tissues covered: epithelial, connective, blood,
muscles (smooth, striated, cardiac) nervous and skin tissues:
b) Identify the various groups of muscles using a carcass
c) Identify the positional and directional aspects of animals
d) Identify histological tissues under a microscope/charts
e) Identify different types of bones
f) Draw cross section of different types of bones
g) Identify the various types of joints
h) Demonstrate the various joint movements
i) Identify the parts of the mammary gland
j) Identify the various types of skins(hides and skins) and associated structures
k) Identify parts of the respiratory system
l) Identify the various gross structures of the lung
m) Demonstrate blood clotting
n) Identify the heart and blood vessels
o) Identify parts of the lymphatic system
p) Identify the superficial lymph nodes
q) Identify parts of the female reproductive system
• TOTAL 45HRS
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10. INTRODUCTION
Definitions :
Veterinary Anatomy is the branch of biological science, which deals with the form
and structure of the body and its parts.
Animal Physiology is the study of how animals work, and investigates the
biological processes that occur for animal life to exist.
Cytology- relates to the study of cells as fundamental units of living things.
Cytopathology- deals with abnormalities of a cell.
Histology is the microscopic study of tissues of an organism.
Histopathology- study of tissues in relation to disease/injury/infection.
Embryology – refers to the study of the development of animals from the
fertilized egg to the new adult organism.
Osteology- morphological study of bones.
Arthrology- study of joints and associated structures.
Myology – study of muscles and associated structures.
Neurology – study of nerves/nervous system.
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12. Branches of anatomy :
1) Cytology – is the study of cells of the body.
2) Histology - uses a microscope to study fine details of structural
tissue cells .
3) Gross anatomy/ macroscopic anatomy –is the study of anatomy at
the visible or macroscopic level.
4) Comparative anatomy – studies forms and structures between
different animal groups e.g. poultry anatomy
5) Special anatomy – study forms and structures of a single species
e.g. the human anatomy
6) Embryology/ Developmental anatomy – Is the study of changes
and development of an animal from conception to birth.
12
13. • WHY STUDY ANATOMY AND PHYSIOLOGY?
Animal anatomy and physiology is key discipline in the field of
veterinary medicine, as fundamental scientific discipline offers vital
foundational knowledge on how the structure of an organ relates to
its function and health.
It also helps in understanding the health status of patients/ animals.
Also aid in assessing, evaluating, diagnosing, and tracking a
patient’s health.
13
14. Positions and directional terms used in anatomy
Descriptive terms are used when referring to the location of body parts. These frames of
reference are in relation to the animal itself and apply regardless of the position or direction
of the animal.
Cranial- towards the head
Caudal- towards the tail
Medial –near/towards the median plane/long axis
Median plane – divides the body into two similar halves
Dorsal – towards the backbone/away from the plane of support(ground)
Ventral –towards the plane of support(ground)
Proximal – Part of the limb nearer along the long axis.
Distal – Part of the limb further along the long axis
Lateral- Away from the median plane or towards the side.
Transverse – cuts the body into cranial and caudal parts.
Sagittal – parallel to the medial plane
Profundus- running deep e.g. muscles
Rostral – towards the nose/muzzle
14
19. Superficial – towards the body surface
Anterior – nearing the head
Posterior – nearing the tail
Palmar – the rear surface of the fore paw that bears the footpads; the opposite
surface (i.e., the front surface of the paw) is the dorsal surface
Plantar – the rear surface of the hind paw that bears the footpads; the opposite
surface (as above) is the dorsal surface.
A transverse plane is at right angles to the median plane and divides the body
into cranial and caudal segments.
A horizontal 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.
19
20. Methods used to study anatomy
i. Applied method
ii. Topographical method/Regional
iii. Systemic method
Applied method/clinical anatomy.
- Is the application of anatomical facts and skills to medicine and surgery.
Topographical method /regional
- Involves studying anatomy of the body based on specific regions and the relations of
the structures contained in that region e.g. the head and the neck, lower extremity and
upper extremity, and thorax, abdomen and pelvis.
Systemic method
- Study of a particular system and its associated parts ,and then moving on to the next
system e.g. digestive system, skeletal system etc.,
20
21. NB :
• Methods of studying anatomy have progressively and dramatically
improved , advancing from the examination of animals by dissection of
carcasses and cadavers (corpses) to 20th centaury medical imaging
techniques (Radiological anatomy) including ;
1) X- ray
2) Echocardiography/ cardiac ultrasound – uses sound waves to produce
images of the heart
3) Ultrasonography – e.g., in pg diagnosis
4) Magnetic resonance imaging – MRI
5) Endoscopy – uses an endoscope to examine internal organs of the
digestive system
6) Computed tomographic scanning (CT scanning)
21
22. CYTOLOGY/ CELL BIOLOGY (Mammalian cell)
A cell is a basic unit of life in organism(s).
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24. Cell organelles and their functions
The nucleus contains the genetic material(DNA) and controls all the activities of the
cell. The nucleus also contains several nucleoli, where the ribosomes are manufactured.
Ribosomes these float free in the cytoplasm and are the site for protein synthesis within
the cell.
Endoplasmic reticulum (ER)- Production, processing and transportation of synthesized
proteins by ribosomes.
Rough endoplasmic reticulum - The function of rough ER is to transport the proteins
that have been synthesized by ribosomes.
Smooth endoplasmic reticulum- are not ribosome attached unlike rough endoplasmic
reticulum and therefore function in storage, synthesizing lipids and steroids and
removal of wastes.
Golgi apparatus – receives proteins from the ER and folds, sorts and packages this
proteins into vesicles (membrane bound compartment)
• Lysosomes- These are membrane-bound sacs that contain lysozymes or digestive
enzymes. Their function is to digest materials taken in by the cell during the process of
phagocytosis or endocytosis. Lysosomes also destroy worn-out organelles within the
cell and, in some cases, the cell itself.
24
25. Cytoplasm – Is a gel like liquid consisting of primarily water, ions ,proteins and small
molecules. Provides nourishment to the cell organelles.
Mitochondria – are energy producing organelles. They break down sugars and fats into
smaller units(ATP) that the cell can utilize.
Cell membrane – Surrounds the cell and support its components. It is selectively
permeable. Functions include :
• Cell membrane surrounds the cell.
• Facilitate cell to cell communication
• Control the rate of certain molecules entering and leaving the cell.
• Support the components of the cell
• Regulation of cell growth through the balance of endocytosis and exocytosis.
• It is selectively permeable to molecules
Centrosome and centrioles – the centrosome contains a pair of rod-like structures called
centrioles. These lie at right angles to each other and are involved in cell division
(mitosis).
Cytoskeleton- consists of microtubules, microfilaments that provide shape and strength
of organelles. 25
27. Cell division
• The cells of the body are classified into two types:
Somatic cells – these include all the cells of the body except those involved
in reproduction. Somatic cells divide by mitosis and contain the diploid
number of chromosomes.
Germ cells – these are the ova (within the ovaries) and the spermatozoa
(within the testes). Germ cells divide by meiosis and contain the haploid
number of chromosomes.
27
28. The chemistry of the body
• The cells, and therefore the tissues and organs, which are all made of cells, are composed of
chemicals. Chemical compounds can be divided into two groups:
Organic compounds are those that contain the element carbon ( Carbohydrates(sugars),
proteins(amino acids), lipids(fatty acids and glycerol)
Inorganic compounds are all those compounds that do not contain carbon (Minerals cations
such as sodium, potassium and magnesium , minerals anions such as chloride ions,
bicarbonate ions)
• Both groups are found in the body, but let us first look at the most biologically important
inorganic compound of the body – water (H2O)
Water content of the body
• An individual mammalian cell contains 80% water. In fact, 60– 70% of the whole body’s
weight is water, which is divided into two main body compartments:
1) intracellular (ICF) and
2) extracellular (ECF) water.
• ICF is that which is found inside the cells of the body and can be subdivided into the fluid
within the blood cells and the fluid in all other cells.
• ICF takes up 40% of total body weight.
28
29. Cont’
• ECF is that which lies outside the cells (i.e., the surrounding environment of
the cells). ECF takes up 20% of total body weight and includes the fluid in
which the blood cells are suspended (the plasma), the fluid within the
lymphatic system (lymph) and the cerebrospinal fluid (the transcellular
fluid) and the fluid that surrounds all the other cells of the body (the
interstitial or tissue fluid).
• Plasma takes up about 5% of body weight. It forms the medium in which the
blood cells are transported within the blood–vascular system. It is rich in
proteins, termed plasma proteins.
• Transcellular fluid is formed by active secretory mechanisms and its volume
varies. It is considered to take up about 1% of body weight and it includes
fluids such as cerebrospinal fluid, digestive juices and lymph. Interstitial fluid
takes up 15% of body weight and lies outside the blood vascular system,
surrounding the cells. It is formed from the blood by a process of
ultrafiltration. 29
30. TISSUES AND BODY CAVITIES
• The cells of the body are arranged into four basic tissue types: epithelial, connective,
muscle and nervous tissue.
Epithelial tissue covers the outside of the body and lines all the body cavities and the
structures within them. Its primary function is to protect but in some areas it may also be
absorbent or secretory. Secretory epithelial tissue forms glands.
Connective tissue is found in varying forms such as blood, fibrous connective tissue,
cartilage and bone. Its main function is to connect and support the parts of the body, but
it also carries nutrients to the tissues and conducts waste material away.
Muscle tissue brings about the movement of the body. It is found as striated muscle
attached to the skeleton, smooth muscle within the internal organs of the body and
cardiac muscle found only in the myocardium of the heart wall. Control of striated
muscle is voluntary, while that of smooth and cardiac muscle is involuntary and brought
about by branches of the autonomic nervous system.
Nervous tissue is found all over the body and its function is to conduct nerve impulses
to and from parts of the body and the central nervous system.
• The body is divided into three body cavities, which contain the visceral systems. The
thoracic and abdominal cavities are lined with a single layer of serous epithelial tissue,
which is named according to its location within the cavity.
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31. • Within the body individual cells are grouped together to form tissues and
organs. Thus:
• A tissue is a collection of cells and their products in which one type of
cell predominates (e.g., epithelial tissue or muscle tissue).
• An organ is a collection of tissues forming a structure within an animal
that is adapted to perform a specific purpose (e.g., liver, larynx, kidney).
• A system is a collection of organs and tissues that are related by function
(e.g., the respiratory system).
31
32. - Epithelial tissue, or epithelium, covers the surface of the body and the
organs, cavities and tubes within it – the internal and external surfaces of
the body. Its main function is to protect delicate structures lying beneath it
but in some areas the epithelium may be secretory (e.g., glands) or
absorbent (e.g., in the small intestine).
- Lines the cavities and surfaces of structures throughout the body.
- Epithelial layers are avascular(lack blood supply). They receive their
nourishment through diffusion of substances across the basement
membrane (which is semi-permeable).
- They’re packed together like bricks leaving very little intracellular
space.
EPITHELIUM TISSUES.
32
33. Functions of epithelium tissues ;
a) Absorption e.g. the small intestines in the GIT
b) Filtration e.g. the kidneys
c) Sensation e.g. sensory epithelia
d) Protection of the skin, viscera and blood vessels.
e) Secretion e.g. salivary glands
33
34. Classification of epithelium tissue :
Epithelium may be described according to the number of
layers of cells (i.e., its thickness):
I. If an epithelium is one cell thick it is said to be simple
II. If there is more than one layer it is said to be stratified or
Compound.
34
35. Cont’
Epithelium may also be described according to the shape of
the cells within it. There are three basic shapes of epithelial cell:
Squamous cells: flattened in shape
Cuboidal cells: square or cube-shaped
Columnar cells: column-shaped (the height is greater than the
width)
35
38. Different types of epithelium and their locations in the body :
Simple cuboidal epithelium - lines many of the glands and their ducts. This type of epithelium has an
absorptive or secretory function depending on its location in the body (e.g., lining the renal tubules).
Simple squamous epithelium - is found in areas of the body where the covering surface needs to be easily
permeable to molecules such as oxygen(e.g., lining the blood vessels and the alveoli of the lungs).
Simple columnar epithelium - lines organs which have an absorptive function (e.g., the small and large
intestines) or a secretory function (e.g., digestive glands)
Ciliated epithelium - lines the upper respiratory tract, where it helps to trap solid particles that have been
inhaled, preventing them from entering the more distal parts of the respiratory system. The uterine tubes are
also lined with ciliated epithelium, which helps to move the fertilized egg along the reproductive tract.
Stratified epithelium - composed of a number of layers of cells and is thicker and tougher than the other types
of epithelium. It is found in areas that are subjected to wear and to friction and shearing forces (e.g., the
epidermis of the skin).
Transitional epithelium - is a type of specialized stratified epithelium found lining parts of the urinary system
(i.e. structures and tubes that are capable of considerable distension and variations in internal pressure and
capacity, such as the bladder and ureters).
Pseudostratified epithelium - appears to be multilayered because of the irregular positioning of the nuclei but is
actually a single layer of cells. This may be found in areas such as the trachea.
38
39. NB;
• Glands may be categorized as either exocrine or endocrine.
Exocrine glands have a system of ducts through which their secretory
products are transported directly to the site where they will be used
e.g., prostrate gland secreting seminal fluid.
Endocrine glands do not have a duct system (ductless glands) and
their secretions, known as hormones, are carried by the blood to their
target organ, which may be some distance away e.g., pancreas
(secreting insulin, anterior pituitary gland secreting ADH, FSH
39
40. CONNECTIVE TISSUES
Are fibrous tissues responsible for supporting and holding all
the organs and tissues of the body in place.
Made up of cells separated by a non living material called the
extracellular matrix/ ground substance.
40
41. Functions of connective tissues
Connect tissues e.g. tendons
Support all other tissues
Bind other tissues together
Protects other body tissues and organs e.g. the ribs
Adipose connective tissue contribute to energy supply in form of fats
Also insulate the body against heat/rays.
41
43. 1. BLOOD
Blood is a specialized connective tissue that circulates via the blood
vessels.
Blood carries oxygen, carbon dioxide and wastes in and out of the cell.
Made of up cellular component (blood cells) and non cellular
components (plasma ,hormones ,nutrients , gases ).
Plasma is the ground substance found in blood.
Plasma is an aq solution of inorganic salts and proteins. These plasma
proteins include :
i. Albumin – maintains the osmotic pressure of the blood
ii. Immunoglobulin – are antibodies e.g. neutrophils
iii. Fibrinogen – contain fibrin that is involved in blood coagulation
43
44. Blood cells
• They make up the solid compartment of the blood
• They are :
1. Red blood cells / Erythrocytes
2. White blood cells / leukocytes
3. Thrombocytes / platelets
44
45. Erythrocytes
Are the most numerous blood cells
In most domestic mammals they are nonnucleated biconcave disks
that contain the protein hemoglobin.
The main function of the RBCs is to carry hemoglobin. Hemoglobin
in turn has the primary function of carrying oxygen from the lungs to
all tissues of the animal.
Function within the blood vessels(so are platelets)
Transport oxygen and co2
Formed within a stem of the bone marrow by a process called
erythropoeisis
45
46. Leukocytes
• Are nucleus present
• Function outside the blood vessels
• Defend the body against infections
• They are five types of leukocytes that are classified into :
A. Granulocytes – are phagocytic cells that contain granules in the cytoplasm.
They’re ;
I. Neutrophil-are phagocytic cells
II. Basophils- secret histamine and heparin
III. Eosinophils-control mechanisms associated with allergy and play a role in
parasitic infestation.
46
47. Cont’
B . Agronulocytes- Have a clear cytoplasm(no granules). They
include
i. Lymphocytes- main type of cells found in lymph. Produce B and T
cells (responsible for immune system). From thymus(T cells and B
cells are from bursa in birds and bone marrow in other animals)
ii. Monocytes – are phagocytic cells and form macrophages
(phagocytosis necrotic debris) when they mature.
47
49. Thrombocytes
• Involved in blood clotting
• Are small disc with no nuclei
• They’re present in blood
• When thrombocytes are decreased in number, we use a
term called THROMBOCYTOPENIA.
49
50. 2. Haemapoetic tissue
Are jelly like connective tissue forming the bone marrow within the long bones.
Are responsible for the formation of blood cells
50
51. 3. Areolar tissue/ loose connective tissues
• Areolar meaning spaces.
• Also called loose connective tissues
• Found all over the body e.g. beneath the skin, around
blood vessels and nerves
• Are made up of two protein fibres, collagen and elastin
that allows stretching and recoiling.
51
52. 4. Adipose tissue
• Made up of fat filled cells closely packed together
• They act as energy reserves
• In the dermis of the skin, they insulate the body thus
preventing heat loss
• Protect the skin from extreme thermal radiation
52
53. 5. Dense connective tissue
• Also called fibrous/ collagenous tissues
• Consists of collagen fibers bundles e.g. tendons
• This fibers are arranged into two ways ;
1) Parallel arrangement – these are regular fibrous
connective tissues e.g. tendon and ligaments with
strong bands
2) Irregular interwoven fibers – seen in the capsule of
joints, lymph nodes and dermis of the skin
53
54. 6. Cartilaginous tissue
• Made up of avascular(no blood) dense tissue called
cartilage
• The cartilage is rigid, flexible and resilient in order to
bear weight.
• Composed of the following cells ;
Chondrocytes – mature cells of the cartilage
Chondroblasts – immature cells of the cartilage
Chondroclasts – resorption/dissolve of warn out
cartilaginous cells. 54
56. 1. Hyaline cartilage
• Has a translucent, bluish white appearance.
• Most common cartilage of the body
• Forms the articular surface of the joint
• Forms the skeleton of the embryo before it becomes ossified
through a process called ENDOCHONDRIAL
OSSIFICATION.
• Provides support to the nose, trachea, larynx/voice box,
bronchus
56
57. 2. Elastic cartilage
• Provides elasticity and rigidity of the body
organ/tissue
• Made up of elastic fibers
• Found in the external ear, epiglottis
57
58. 3. Fibrous cartilage
•Forms semi elastic cushions
•Have considerable strength
•Found in areas where tissues are exposed to
pressure e.g. intervertebral disc, stifle joint
(cruciate and collateral ligament), shoulder joint
• It also attaches the tendons and ligaments to
bone.
58
59. 7. Bone tissue/ Osseous tissue
• Made of connective tissue forming the skeleton
• Has extensive vascular network
• Made up of specific bone cells ;
Osteoblasts – immature bone cells
Osteocytes – mature bone cells
Osteoclasts – necessary for resorption
59
60. Cont’
• Calcification (calcium deposition) gives the bones its rigidity
and hardness.
• A fibrous membrane called PERIOSTEUM covers the outer
surface of all types of bones.
• Bone tissue has two layers :
I. Compact layer
II. Spongy/ cancelleous layer
60
61. Cont’
• Compact layer
Forms the solid and outer layer of the bone
The haversian systems of compact bones are densely packed
together.
Haversian system contains canals that carry blood vessels
and nerves.
• Spongy layer
They are found in the end of long bones, and in the core of
short and flat bones.
61
62. Structure of a bone
• Compact (dense or cortical) bone is the hard layer that constitutes the exterior of most bones and
forms almost the entire shaft of long bones.
• Cancellous (spongy) bone is composed of spicules arranged to form a porous network. The spaces are
usually filled with marrow.
• The medullary cavity (marrow cavity) is the space surrounded by the cortex of a long bone.
• In young animals it is filled with red marrow(hematopoietic tissue), which gradually is replaced by
yellow marrow (fat) as the animal ages.
• Epiphysis refers to either end of a long bone. The end closest to the body is the proximal epiphysis,
and the end farthest from the body is the distal epiphysis.
• The diaphysis is the cylindrical shaft of a long bone between the two epiphyses.
• The metaphysis of a mature bone is the flared area adjacent to the epiphysis.
• Epiphyseal cartilage or disk (physis) is a layer of hyaline cartilage within the metaphysis of an
immature bone that separates the diaphysis from the epiphysis. This is the only area in which a bone
can lengthen.
• Articular cartilage is a thin layer of hyaline cartilage that covers the articular (joint) surface of a bone.
• Periosteum is a fibrous membrane that covers the surface of a bone except where articular cartilage is
located. Osteoblasts (bone-producing cells) of the periosteum are responsible for increases in the
diameter of bones, and activity of periosteal cells is important in the healing of fractures. The
periosteum is vascular and well-innervated.
62
66. Functions of bones
• Gives shape to the animal
• Provide support when they are attached to muscles
during movement
• Protect delicate organs e.g. bones of the skull protect
the brain
• Acts as the center of growth
• Storage organ for minerals (Ca and P)
66
67. THE MUSCLE TISSUE
• A muscle is a locomotory organ.
• It is made up of cells called muscle fibers.
• A muscle fiber is a long, cylindrical cell which may contain a single
or multiple nuclei.
• It is capable of contracting and relaxation
• Also capable of transmitting impulses from one muscle fiber to
another.
• Muscle fibers are surrounded by membrane called sarcolemma
• The cytoplasm of the muscle fiber is called sarcoplasm, which
contains a bundle of myofibrils. 67
68. Cont’
• Myofibrils contain the contractile protein called myosin and actin,
(thick and thin filaments)which slide through each other during
contraction.
• Muscle cells don’t regenerate/rebuild after damage, they grow through
cell enlargement.
68
69. Classification of muscle tissues
1. Skeletal or striated muscle/ voluntary
2. Smooth/ non striated muscle/ involuntary
3. Cardiac muscle/ involuntary
69
70. Skeletal muscles
• Found attached to the skeleton via an origin and insertion points
• Bring about movement
• It is under voluntary control
• Muscle fibers are long and cylindrical and like parallel to each
other
• Muscle fibers are grouped together in bundles called fascicles
• Myofibril contains the contractile protein, myosin and actin.
They give skeletal muscles the striation characteristic.
• Examples of skeletal muscles – deltoid muscle of the shoulder.
70
71. Smooth muscles
• Are non striated and involuntary
• Also called visceral
• They are spindle shaped with a central nuclei
• Contract continuously and rhythmically
• Control by the ANS and hormones e.g. gastrin
• Have low force of contraction
• Muscle fibers are shorter.
• Found in hollow organs e.g. in the GIT, vascular smooth muscles in
vessels especially arteries.
71
72. Cardiac muscle
• Found exclusively on the walls of the heart
• Forms the myocardium of the heart
• Control is automatic and involuntary
• They have a cross type of shape
• Muscle fibers are enlarged.
• Each muscle fiber has one or more branches of network called
intercalated disc. These enable the nerve impulses to be conveyed
across the myocardium quickly, thus producing a rapid response to the
changing needs of the body.
• Well supplied by blood vessels
72
75. The nervous tissue.
Made up of cells called neurons, whose function is to transmit nerve
impulses from one area to another.
Each neuron consists of a cell body, containing the nucleus, several short
processes called dendrons and one long process called the axon.
Dendrons carry information towards the cell body, while axon carries
information away from it and towards its destination.
Many axons within the body are covered in a fatty material called
myelin. This is secreted by specialized cells(schwann cells) wrapped
around each axon.
Myelin sheath is not continuous and there's gap called node of ranvier.
Nerve impulses are transferred from one neuron to another by means of
button like structures known as synapses.
All nerve pathways consists of neurons and synapses.
75
79. The body cavities
These are separate areas dividing the body.
They are completely filled visceral/internal organs and fluid.
All body cavities are lined with a serous membrane or
endothelium, which is a single layer of epithelium that
produces a watery or serous lubricating fluid.
79
80. There are three body cavities :
1) Thoracic
2) Abdominal
3) Pelvic
80
81. The thoracic cavity
Contains the heart ,lungs and other associated structures.
Its skeletal walls are formed by the bony thoracic cage, consisting the
ribs, thoracic vertebrae and sternum.
The entrance into the cavity is known as the cranial thoracic inlet and
is formed by the first thoracic vertebrae, the first pair of ribs and
manibrium.
The exit or caudal border is filled by the diaphragm.
The serous membrane lining the thoracic cavity and its viscera is
known as pleura.
81
82. The abdominal cavity
Lies caudal to the thoracic cavity and contains the abdominal viscera.
These include organs of the digestive system and related glands, the
urogenital system and all the associated vessels and nerves that supply
these systems.
The abdominal cavity is bounded cranially by the diaphragm and
caudally by the pelvic inlet.
Dorsally, the boundary is the lumbar vertebrae and hypaxial & epaxial
muscles of the trunk
The serous membrane lining the internal surfaces of the abdominal
cavity is called peritoneum.
82
83. The pelvic cavity
Lies caudal to the abdominal cavity and contains the urinary bladder,
the rectum and the reproductive organs. There is no physical
separation between the two.
The cavity is bounded cranially to the pelvic inlet and caudally by the
pelvic aperture.
The sacrum and the first coccygeal vertebrae form the dorsal
boundary and the pubis and ischium form the floor of the cavity.
The walls are formed by muscles and ligaments.
83
85. OSTEOLOGY/ SKELETAL SYSTEM.
Osteology is the study of structure and function of the skeleton
and bony structures.
The skeletal system forms the framework upon which the body is
built.
It provides support, protection and enables the animal to move.
The joints are considered to be an integral part of the skeleton.
The SS is made up of specialized connective tissue, bone and
cartilage.
85
86. Functions of the skeletal system
• Supports the body
• Brings about mov’t – locomotion
• Protects the underlying parts of the body e.g. brain
• Storage of essential minerals(Ca & P)
• Haemopoiesis – haemopoietic tissue( bone marrow) manufactures the
blood cells.
• Gives the shape of the animal.
86
87. Classification of bones
• Bones are categorized according to their shapes and mode of development :
a) Long bones – are typically the limb bones and develop by a process called
endochondral ossification. They have a shaft containing a medullary cavity
filled with bone marrow. Also covered by periosteum membrane. Examples
of long bones :
Humerus
Femur
Tibia
Fibula
Ulna
Radius
Metacarpus, metatarsus and phalanges.
87
88. Cont’
b) Flat bones – have an outer layer of compact bone with a layer of
spongy bone inside. Have no medullary cavity. Example are ;
scapula
bones of the skull
Ribs
c) Short bones – have a outer layer of compact bone with a core of spongy
bone and no medullary cavity . Examples :
Carpal bone
Tarsal bone
88
89. Cont’
d) Irregular bones – have similar structure to short bones but a less uniform
shape. They lie in the midline and are unpaired. Example :
Bone of the vertebrae
e) Sesamoid bones – are sesame shaped and develop within a tendon that
runs over an underlying bony prominence. They reduce wear and tear by
changing the angle at which the tendon passes over the bone. Examples
patella associated with stifle joint.
f) Pneumatic bones – contain air filled spaces known as sinuses thus
reducing bone weight. Examples :
Maxillary bone
Frontal bone
89
92. g) Splanchnic/visceral bones – develops in soft organs. Example :
Os penis bone within the dogs, fox, raccoon and cat penis.
Os cordis in the heart of cattle
Os nostra/rostri in the nostril/snout of pigs
Os phrenic in the diaphragm of camels
DEVELOPMENT OF THE BONE.
The process by which bones are formed is called ossification and there
are two types ;
1) Intramembranous ossification
2) Endochondral ossification 92
93. • Intramembranous ossification – process by which flat bones of the
skull are formed. The osteoblasts lay down bone between two layers of
fibrous connective tissue.
• Endochondral ossification – involves replacement of hyaline
cartilage model within the embryo by bone. Long bones of the limb
develop by this process.
93
94. THE SKELETON
• There are 3 types of skeletons in animals
I. Endoskeleton – found in vertebrates . Made up of
framework of bones and cartilages .
II. Exoskeleton – made up of hard, protective outer
covering. Exists in arthropods e.g. tick, crab ,beetle
III. Hydrostatic skeleton – formed by a fluid-filled
compartment e.g. in earthworm, jellyfish .
94
95. Division of the skeleton
• The skeleton can be divided into three parts:
A. Axial skeleton – runs from the skull to the tip of the tail and includes
the skull , mandibles, vertebrae and sternum.
B. Appendicular skeleton – consists of pectoral (front) and pelvic (hind)
limbs and the shoulder and the pelvic girdles that append/attach them
to the body.
C. Splanchnic skeleton – in dogs and cats is rep by the os penis within
the tissue of the penis, os cardis in bovine heart .
95
97. Axial skeleton
The skull
oBones of the head include the skull, nasal chambers, mandible or
lower jaw and hyoid apparatus. The functions of the skull are :
1. House and protect the brain
2. House special sense organ – eye, ear, nose and tongue
3. Provide attachment to parts of the digestive system – tongue,
teeth
4. Provide attachment to muscles of mastication.
5. Provide bony cavity through which air can enter.
97
99. Cranium
• Is the caudal part of the skull
• Provide a bony case in which the brain sits
• Bones of the cranium include :
1. Parietal – forms much of the dorsal and lateral walls of the cranium
2. Temporal – lies below parietal bone on the caudal lateral surface of
the skull. Ventral part of temporal bone forms a round prominence
called the tympanic bulla, which houses the structure of the middle
ear .
3. Sphenoid - lies on the ventral aspect of the skull, forming the floor of
the cranial cavity.
4. Zygomatic arch – born that projects laterally from the skull forming
cheekbone.
99
100. Cont’
5. Lacrimal – lies at the base of the orbit which houses the eye .
6. Frontal bone – forms the forehead and contains an air filled
chamber called the frontal sinus, which connects to the nasal
chamber.
7. Occipital – lies at the base of the skull on the caudal aspect. In
this region there is a large hole called the foramen magnum,
through which the spinal cord passes. On either side is a pair of
bony prominences ,the occipital condyles. This articulate with
the first cervical vertebrae/ Atlas.
100
108. Nasal chambers
ch chamber is filled with delicate scrolls of bones called nasal tubinates/
chae .Many bones of the skull are joined together by firm, immovable joints
ed sutures.
e roof of the mouth is called the hard plate and is formed from three bones :
1. Incisive bone/ premaxilla
2. Maxilla
3. Palatine
108
110. Mandible/ Lower jaw
• Comprises of two halves or dentaries, joined together at the chin
by cartilaginous joint called the mandibular symphysis.
• Is divided into the body( that carries sockets for the teeth), and the
ramus ( articulates with the rest of the skull at the
temporomandibular joint via a projection called the condylar
process.
110
112. Hyoid apparatus
•Lies into the intermandibular space.
•Consists of a number of fine bones and cartilage joined
together like a trapeze.
•They are the means by which larynx and tongue are
suspended from the skull.
•Articulates to the temporal region of the skull in a
cartilaginous joint.
112
114. Skull shapes
Overall appearance defers greatly, although the anatomy remains the same
among different breeds.
Three morphological shapes in dogs are recognized :
I. Dolichocephalic – the head particularly the nose is long and narrow e.g.
afghan hound
II. Mesaticephalic – is the normal or average shape of the dog skull e.g.
beagle, labrods dogs
III. Brachycephalic – the cranium is rounded and nose is short and pushed
inwards e.g. bulldog, boxers.
114
116. THE VERTEBRAE
• Consists of a number of bones arranged in a series along the midline .
• Extends from the base of the skull to the tip of the tail.
• The vertebrae articulate to one another by two types of joints (Cartilaginous
and synovial)
• It is divided into regions depending upon their positions :
1) Cervical (C) – Neck region
2) Thoracic (T) – Thoracic region
3) Lumbar (L) – Lower back or abdominal region or loin
4) Sacral (S) – Croup or pelvic region
5) Caudal or coccygeal (C) – In the tail .
116
117. Cont’
• Structural parts of the vertebrae bone are ;
The body
The arch
Spinous process
Transverse process
Transverse foramen
Articular surface (joint) – Thoracic
Vertebral foramen
Lamina
117
123. Functions of the vertebral column
• Stiffen the body axis and help maintain posture
• Enclose and protect the spinal cord
• Shield and protect softer underlying structures of the
neck, thoracic, abdomen and pelvis
123
124. Cervical vertebrae
• Almost all mammals have 7 cervical vertebraes except most birds (C14)
• The first C1 is the Atlas and carries the head and the neck of an animal.
• Cervical bones don’t have a body or a spinous process, but consists of
two mass like lateral wings.
• The axis is the second C bone and largest vertebrae in all animals expect
in pigs
• Axis has a dense process which projects cranially towards the head and
articulates ventrally with atlas
• The C3 – C7 are characterized by transverse process which have two
parts, one projecting ventrally and other laterally.
• C7 has only lateral portion of the transverse process.
124
125. Thoracic vertebrae
•Characterized by prominent/tall spinous process and short
bodies
•Are usually 13 in number.
•Have articular surfaces where the ribs attached
•The last thoracic vertebrae articulates only cranially with
the ribs while the other thoracic vertebrae have both
cranial and caudal articulation with the ribs.
125
126. Lumbar vertebrae
• These are usually 7 lumbar vertebrae
• Characterized by well developed transverse process.
• Have spinous processes that aren’t prominent as those
of the Thoracic Vertebrae.
• Normally gives a flexible movement in dogs and cats.
126
127. Sacral vertebrae
•Have fused bones to form the sacrum.
•Has got four main parts/ surfaces - dorsal surface,
pelvic surface, cranial base, and caudal apex
127
128. Coccygeal vertebrae
• Forms the skeleton part of the tail.
• The bones diminish in size from first to the last.
• Towards the tail end, the bones tend to be incomplete
loosing the typical vertebrae structure.
128
131. THE RIBS AND THE STERNUM
• The ribs forms the walls of the bony thoracic cage that protects the
organs of the chest.
• There are 13pairs of ribs in most domestic animals, which articulate
with the thoracic vertebrae.
• A rib is a flat bone consisting of compact bone on the outside packed
with cancellous bone on the inside.
• Each rib has a bony dorsal part and a cartilaginous ventral part , the
costal cartilage.
• The most dorsal part of the rib has two projections ; the head, which
articulates with the costal fovea of the vertebra, and the tubercle/
neck, which articulates with the transverse fovea of the appropriate
thoracic vertebra. 131
134. Cont’
• The costal cartilage articulates with the sternum, either directly or
indirectly .
• The first eight pair of the ribs attach directly to the sternum and are
called the sternal bones.
• The ribs from pairs 9 to 12 are called asternal or false ribs and
attach via costal cartilages to the adjacent rib, forming the costal
arch.
• The last rib (pair 13) have no attachment at their cartilaginous ends,
which is free in the abdominal muscle – this pairs are called
floating ribs.
134
135. Cont’
• The space between each successive pair is called the intercostal
space and is filled with intercostal muscles of the trunk.
• The sternum forms the floor of the thoracic cage and is
composed of eight bones, (the sternebrae ), and the
intersternebral cartilages
• The most cranial sternebra is the manubrium, which forms part
of the cranial thoracic inlet.
• The last sternebrae is longer and dorsoventrally flattened ,its
called xiphoid process.
• A projection of xiphoid process forms a xiphoid cartilage.
135
137. APPENDICULAR SKELETON
Composed of :
Pectoral (fore) limb
Pelvic (hind) limb
The shoulder and the pelvic girdle
The fore limb has no bony connection to the trunk, only being attached
by muscles.
The hind limb does have a bony articulation in the pelvic girdle, which
forms the platform for the muscles that provide the propulsive forces
as the animal is running.
137
139. Bones of the forelimb
• Clavicle/ color bone – frequently absent in dogs. It is normally present in
cats but does not articulate with other bones. Birds and primates possess a
clavicle which forms a joint with the scapula, but in most quadrupeds (four
footed animal), the clavicle is represented only by the clavicular tendon, a
connective tissue band within the brachiocephalicus muscle
• Scapula/ – also called the shoulder blade. It’s a large flat bone found on the
lateral side of the trunk, at the junction of neck and ribs. It has a prominent
ridge/ spine running down the middle of its lateral surfaces. This divide the
lateral surfaces into two regions : supraspinous fossa and infraspinous
fossa. On the distal end there is a projection called the acromion. The
glenoid cavity forms the shoulder joint with head of the humerus.
139
145. Continuation
• Humerus (arm bone) – long bone forming the upper forelimb. Articulate proximally with the
scapula at shoulder joint, and distally with the radius and ulna, at the elbow joint. The distal
end of the humerus is the condyle. Just proximal to this is a deep hollow called the olecranon
fossa, that receives the process of ulna.
• Radius and ulna – are long bones that lie side by side in the forearm . At the proximal end of
the ulna is a projection known as olecranon, which forms the end of the elbow. In mammals,
the radius is the larger of the two, although in birds it is smaller than the ulna
• Carpus – composed of 7 short bones, the carpal bones ; arranged in proximal and distal rows.
They include :
- proximal carpal bone
- distal carpal bone
- radial carpal bone
- intermediate bone
- ulnar carpal bone
- accessory carpal bone
- pisiform.
145
146. Cont’
• In dogs the radial and intercarpal bones are fused. On the distal row we have
the 1st, 2nd and 3rd carpal bones. The 1st carpal bone is small and inconsistent.
The 2nd and 3rd carpal bones are fused in ruminants.
• Metacarpal bones – composed of five small bones . They articulate
proximally to distal row of carpal bones and distally with phalanges.
• Digits – this are composed of phalanges, which are long bones (proximal,
middle and distal phalanges). The distal phalanx ends in ungual process,
which forms part of the claw or hooves.
146
150. Bones of the hind limb
• The pelvis
Provides means by which the hind limb connects to the body
Consists of two hip bones or ossa coxarum, which joins together at the
pubis symphysis.
They form a firm articulation with sacrum at the sacroiliac joint (between
vertebrae and pelvic).
Each hip bone is formed from three bones : ischium, ilium and pubis,
which meet each other at acetabulum (Articular socket in which the head of
the femur sits, forming the hip joint ) - ball and socket joint
A large opening created by the ischium and pubis of the pelvis forms the
obturator foramen, in which nerves and blood vessels open in it (obturator
nerve, artery and veins that supply the pelvic region)
150
154. Cont’
• The femur/ thigh bone
Forms the skeletal parts of the thigh.
Is a long bone.
Proximally articulates to the acetabulum of the pelvis.
Has medial and lateral condyles that articulate distally to the tibia
at the stifle joint.
The patella runs between the condyles in the trochlea groove
154
157. Cont’
•Patella
Is a sesamoid bone
Found within the tendon of insertion of the quadriceps
femoris muscle, which is the main extensor of the
stifle .
Articulates with the femur in the medial side by use of
a ligament (the patella ligament)
157
159. • Tibia and fibula
These long bones forms the lower legs
They lie parallel to each and the medial bone (tibia) is larger.
Proximally, tibia articulates with the femur.
On the dorsal surface, there is a prominence called the tibia crest ,
for attachment of quadriceps femoris muscle.
Distally, the tibia has a prominent protrusion, the medial
malleolus.
Fibula is a thin long bone lying laterally to the tibia . It ends in a
bony point called the lateral malleolus.
159
160. • Tarsus / the hock
Formed from 7 short bones , tarsal bones
Are arranged in 3 rows : proximal, intermediate/middle and
distal rows .
The two bones forming the proximal row are the talus and
calcaneus/hock bones, which articulate with the distal end of
tibia and fibula at the hock joint.
The distal row is made of two bones ( metatarsal bone).
160
161. Metatarsus and digits.
Closely resemble the pattern of metacarpus and digits in the
forepaw.
Composed of 4 metatarsal bones, although some breeds poses five .
There are three digits ; 1st, 2nd and 3rd .
In bovine the metatarsus articulate to the fetlock, pastern and coffin
joint.
Note – the power of regeneration of bone tissue is very high and
after a fracture the bone heals almost back to normal without a scar.
161
163. Arthrology/Syndesmology.
• Arthrology is the study of the articulations (unions) between
bones, which are commonly called joints.
• Syndesmology is the branch of anatomy that deals with science
of ligaments.
• Also known as arthrosis.
• Joints forms an articulation of one bone to another.
• Joints are classified according to :
1. Type of tissue present (fibrous, cartilaginous or synovial )
2. By degree of movement permitted – ( synarthrosis/
immovable, amphiarthrosis / allowing some degree of
movement or diarthrosis / freely movable )
163
164. Types of joints
A. Fibrous
B. Cartilaginous
C. Synovial.
NOTE : The above type of joints are both under the two classifications of
joints.
164
165. Fibrous joints
• Bones forming them are united by dense connective tissue, e.g. in the skull,
fibrous joints unite majority of the bones and are called sutures.
• The teeth are attached to the bony socket in the jaw bone by fibrous joints.
• The implantation of a tooth in its alveolus by means of fibrous union known as
GOMPHOSIS.
• Also classified as synarthroses, a type of joint that permits little or no
movement.
• Are divided into;
1. Sutures – are immovable fibrous joints e.g. joints between bones of the skull.
2. Gomphoses- attachment of tooth to its socket by fibrous periodontal
ligament.
3. Syndesmoses – two bones bound by a collagen fiber/ ligament e.g. joint b2n
tibia and fibula.
165
166. Cartilaginous joints
• Allow limited or no movement at all and are united by cartilage, such as the
pubis symphysis connecting the two hip bones and mandibular symphysis
joining the two halves of the mandible.
• These joints are classified as synarthroses.
• Divided into :
i. Symphyses- the left and right pubis unite at the pubis symphysis.
ii. Synchondroses – joints united by a cartilage e.g. first rib attachment (costal
chondral junction)
166
167. SYNOVIAL JOINT
• Defined by a presence of fluid filled cavity contained within a fibrous capsule. Are freely
movable (diarthroses - allow wide range of movements.)
• Synovial membrane lines and protects joint cavity by secreting synovial fluid ( lubricate the
joint and provide nutrition to the hyaline articular cartilage. This joints are classified into two :
1) Simple joints – formed by two articular bones e.g. the hip and shoulder joints
2) Composite joints – formed by more than two articular bones / surfaces e.g. stifle joint
• All movable joints consist of the following.
1. Articular cartilage
2. Articular surfaces/ joint cavity
3. Synovial fluid
4. Synovial membrane – secrets synovial fluid.
5. Ligament
6. Nerve and blood vessels (aponeurosis)
7. Menisci / articular disc 167
168. Classification of synovial joints
Condylar joints – a convex surface articulates with a concave cavity e.g.
temporomandibular joint between the mandible and the skull
Ball and socket joints/Spheroid - where the ball shaped surface of one
rounded bone fits into the cuplike depression of another bone e.g. hip
(coxofemoral) and shoulder (femorotibial) joints
Pivot/ trochoid joint – allows for rotation only e.g. atlantoaxial joint
Hinge joint/ Ginglymus – permits movement in one plane usually flexion
and extension e.g. stifle and the elbow joints, fetlock joint.
168
173. Range of movements possible in synovial joints
is :
• Flexion – reduces angle between two bones
• Extension – increases angle between two bones
• Abduction – moves the body part away from the median plane / axis
• Adduction – moves the body towards the axis
• Rotation – twisting movement of a segment around the axis
• Circumduction– movt of an extremity in a circular manner.
• Gliding/sliding – articular surfaces of joints slides over one another e.g. patella
and femur.
• Protraction – moving the limb cranially
• Retraction – moves the limbs towards the body
173
176. Joints of the forelimb.
• Clavicle joint – b2n the vertebrae column and scapula
• Shoulder joint – b2n the humerus and the glenoid cavity of scapula
• Elbow joint – b2n the distal part of humerus and proximal part of
radius and ulna
• Carpal joints – distal part of the radius and ulna and proximal
metacarpal bones
• Metacarpal and phalangeal joints – fetlock, pastern, coffin joints
176
183. MYOLOGY - MUSCULAR SYSTEM
Myology is the study of the structure, arrangement, and action of muscles.
All muscles consists of a belly, a point of attachment to a bone, an origin (fixed point
of attachment and RARELY moves during contraction) and an insertion point ( is the
movable distal part of the muscle)
Muscle tissue is always under a degree of tension, known as muscle tone.
The tone increases when an animal is alert or frightened and decreases when it is
relaxed/ asleep.
The muscular tissue is under voluntary control
The nerve stimulates muscle contraction. The nerve splits up into the muscle fibers to
bring about innervation.
A single nerve together with the muscle fibers that it supplies is called motor unit.
The junction between a nerve fiber and a muscle fiber is called the neuromuscular jxn
and a chemical called acetyl choline transmits the impulses across the gap.
183
184. Muscle contraction
• Muscle is stimulated to contract when it receives a nerve impulse from the
CNS. Myofibrils are made of thin actin filaments and thick myosin filaments,
which overlap to form bands / striations. These bands are separated into units
called sarcomeres, which are units of contraction.
• During contraction the heads actin and myosin filaments slide over one
another forming a crossbridge, pulling the thick filaments pasts the thin one,
and sarcomeres shortens.
• Once this movement is completed , the crossbridge detaches itself from the
thin filaments and reattaches itself further away, thus shortening the muscle.
• This process require energy input (ATP) and Calcium ions are also essential .
• The nerve that stimulates the muscle to contract enters the muscle and then
splits up into many fibers for innervation.
184
189. Skeletal muscle can either be divided as ;
I. Intrinsic muscles – lies completely within one region of the body where
they have their origin and insertion. They act on the joints in that part only
e.g. the dog bends the elbow using the intrinsic muscles of the forelimb
II. Extrinsic muscles – runs from one region of the body to another and alter
the position of the whole part (e.g. a limb) in relation to the other. The
muscles that attach the foreleg of the dog to the trunk are extrinsic. They
move the whole foreleg in relation to the trunk.
189
190. Functional groups of muscles
• Extensors - muscles which increase the angle b2n joints e.g. triceps brachii
• Flexors – these muscles decreases the angle b2n joints e.g. bicep brachii
• Adductors – group of muscles which move the limb towards the median plane e.g.
gracillis
• Abductors – groups of muscles which move the limb away from the median plane
e.g. trapezius
• Cutaneous muscles – muscles attached to the skin responsible for twitching e.g.
cutaneous omobrachialis and cutaneous trunci in horses are fly deterrent .
• Sphincter muscles – group of muscles which surround body openings e.g. orbicularis
oris (mouth), orbicularis oculi (eyelids), internalvaginal sphincter , esophageal
sphincter ,urethral sphincter.
• Synergistic muscles – group of muscles working together for a particular motion e.g.
gluteus maximus and hamstrings while running, rear deltoid and biceps while
rowing.
• Antagonistic muscle – pair of muscles that act as opposing force in contraction and
relaxation. E.g. biceps and triceps.
190
191. Muscle organization
• Muscle fibers are bundled as unit within the whole muscle to form
FASCICLES. This organization can be divided into ;
a) Bipennate – fascicles are on both sides of the tendons e.g. rectus femur
b) Unipennate – fascicles are located on one side of the tendon e.g. extensor
digitorum of the forearm
c) Multipennate – fascicle form a complex arrangement b2n the tendons e.g.
deltoid muscle of the shoulder
191
