VETA 50: Microscopic Anatomy I (PDF)

VETA 50: MICROSOCPIC ANATOMY I 2. TOPOGRAPHIC ANATOMY – relative positions INTRODUCTION of the various parts of the body are accurately Branch of science that deals with the form and determined....

VETA 50: MICROSOCPIC ANATOMY I 2. TOPOGRAPHIC ANATOMY – relative positions INTRODUCTION of the various parts of the body are accurately Branch of science that deals with the form and determined. structure of all organisms. Morphology of the animals 3. APPLIED ANATOMY – anatomical facts in Morphology – form and structure of an organism relation to surgery, physical diagnosis, and other (shape, location, texture) practical branches. Describing its morphology Greek word anatome – to cut into or to open a HISTORY OF THE CURRENT MEDICAL ETYMOLOGY AND ANATOMICAL NOMENCLATURE particular structure; the art of separating the parts of an organism in order to ascertain their position, Anatomy – different terms relations, structure, and function. 1895 Basle Nomina Anatomica 1955 Nomina Anatomica – International Congress of HOW DO WE STUDY ANATOMY? DIVISIONS Anatomists in Paris 1986 6th ed of Nomina Anatomica – published by 1. MACROSCOPIC OR GROSS ANATOMY - study of structure of the body (tissues and organs) with Churchhill Livingstone 1968 Nomina Anatomica Veterinaria – publishes by the naked eye. International Committee on Veterinatu Anatomical Nomenclature (appointed by the Word Association of 2. COMPARATIVE ANATOMY – study of structure of different animal species; focusing on the Veterinary Anatomists) 1994 4th ed of Nomina anatomica veterinaria distinct anatomical differences and correlations between these differences. e.g., The bones of the dog’s forearm are composed of 2 bones; radius and ulna VETA 50: TOPOGRAPHICAL AND DIRECTIONAL TERMS USED IN ANATOMY Horse – fused in a singular bone called radioulnar PLANES 3. MICROSCOPIC ANATOMY (cytology and 1. MEDIAN PLANE - an imaginary plane passing histology) – study of cells and structural through the body craniocaudally. It divides the organization of tissues, organs, and systems with body into equal right and left halves. the use of microscope. Nasa gitna ng body a. ULTRASTRUCTURAL CYTOLOGY – Median – strictly at the middle of the animal study of ultrastructural feature of cells The animal only has one median plane (very minute structural details cellular components) with the use of an electron 2. SAGITTAL /PARAMEDIAN PLANE - any plane microscope. parallel to the median plane b. PATHOLOGIC ANATOMY – study of Paramedian = parang median, malapit sa organs functionally deviating from the median normal. The animal can have a lot of paramedian plane 4. EMBRYOLOGY – study of the developmental anatomy (ontogenesis); beginning from 3. TRANSVERSE PLANE - plane at right angles or fertilization to birth of the offspring. perpendicular to the median plane (cross-section of body); dividing the body into cranial and caudal METHODS OF STUDY parts. 1. SYSTEMATIC APPROACH – the body is Can be called “cross-sectional plane” – the regarded as consisting of systems of organs section is directly at across with the median which are similar in origin and structure and are plane associated in the performance or certain functions. 4. DORSAL PLANE - plane at right angles to both a. Skin – dermatology median and transverse plane. Dividing the trunk b. Bones – osteology into a dorsal and ventral part. c. Muscles – myology ‘Yung nasa ibabaw ng animal is already the d. Visceral – splanchnology (splanch – dorsal plane visceral organs) Dorsum – buong likod ng animal; ibabaw e. Nerves brain – neurology f. Blood vessels and the heart – angiology and cardiology g. Sensory organs – esthesiology (anesthesia) For better visualization: The inner surface of the limb is closer to the median plane; therefore, it is the MEDIAL surface of the limb. 5. LATERAL - means away from the median plane The outer surface of the limb is the LATERAL surface. 6. DORSAL - means toward or beyond the vertebral column or backbone. Dorsum – the dorsal portion of the back (ibabaw) E.g., Ibabaw ng ulo ng aso, sa may forehead na part = dorsal surface Dorsal surface ng paw = dorsal pa rin 7. VENTRAL - means away from the vertebral column, towards the mid-abdominal wall. It is used for parts of the body far from the vertebral column (ilalam ng body) E.g., Ilalim ng ulo ng aso, sa may chin part = ventral surface Ventral surface ng fore paw (fore limb) – PALMAR Hind paw (hind limb) = PLANTAR Note: Sa animals, ‘yung ventral surface ng paw ay pwedeng mabago para magkaroon ng denomination ang fore limb and hind limb. AREAS/LOCATION 8. DEEP AND INTERNAL - refer to closeness to the 1. CRANIAL AND ANTERIOR - mean more center of gravity or center of extremity. towards or relatively closer to the head. The term Structures found inside the skin. applies to the limbs proximal to the carpus and tarsus. 9. SUPERFICIAL AND EXTERNAL - refer to Towards the head (used as a reference proximity to skin or surface of body or surface of point) an extremity Pinaka-superficial na structure ng animal is 2. CAUDAL AND POSTERIOR - mean more its skin. towards the tail. e.g., 2 layers of muscle Towards the tail (used as a reference Ibabaw = superficial; ilalim = deep point) There are some muscles na may 3 layers, ang tawag sa E.g., The hind limb is more caudal than gitna ay MIDDLE the fore limb. Middle – any other structures that are found in the middle There can never be any structure that of the superficial and deep can be more caudal than the tip of the tail. Note: Any structures na may mga layer ay pwede gamitan Note: Cranial and caudal are used when we are talking ng deep and internal and superficial and external. about the whole body. 10. PROXIMAL - means close to a given part usually 3. ROSTRAL - means toward or close to the nose body, vertebral column or center of gravity. It is (used only when referring to structures of the usually used in reference to the limbs (parts of head) limb near the vertebral column) The eye is more caudal than the nose, Proximity = malapit; Proximal = malapit sa while the nose is more rostral than the body eye. Also used at the limbs There can never be any structure that can be more rostral than the nose. 11. DISTAL – used for parts of the limb far from the vertebral column 4. MEDIAL - means toward or close to the median Distant = malayo; Distal = malayo sa body plane. e.g., Index finger Usually used at the limbs; inner and outer There are three segments in the index finger (phalanges): surface 1. Proximal phalanx – pinakamalapit sa katawan  2. Distal phalanx – dulong segment 9. ABDUCTION – movement away from the median 3. Middle phalanx – nasa gitna plane Pertaining the limbs 12. AXIAL – situated around, in the direction of, on, Hinila ang limb palayo sa katawan or along an axis Pertaining to the limbs 10. ADDUCTION – movement towards the median AXIS - a straight line about which a body plane or a geometric figure rotates or may be Movement pabalik sa katawan supposed to rotate; a straight line with respect to which a body region is symmetrical; central line of the body or any of its parts 13. ABAXIAL - situated out of or directed away from the axis E.g., The skeleton of the horse na makikita sa gitna ng body is called AXIAL SKELETON. ‘Yung nasa limbs naman is called APPENDICULAR/ABAXIAL SKELETON. MOVEMENT/DIRECTION 1. DORSAD - movement towards the vertebral column Movement towards the dorsum (pataas) 2. VENTRAD - movement away from the vertebral column (pababa) Movement towards the ventrad e.g., Transect the skin from dorsad moving ventrad 3. CAUDAD - movement towards the tail Towards the caudal region 4. CRANIAD - movement towards the head Towards the cranial region e.g., Move the forelimb of the animal caudad – hihilahin palikod (towards the tail) Craniad – hilahin paharap 5. PALMAR/VOLAR - flexion or caudal surface of forelimb below the elbow Movement to palmar surface 6. PLANTAR - caudal surface of hindlimb below the hock joint or ankle Movement to plantar surface 7. PRONE/PRONATE - position in which the dorsal aspect or dorsum of body or extremity is uppermost Pronation - turning toward a prone position Pronate – nakadapa E.g., Planking position 8. SUPINE - position in which the ventral aspect or dorsum of body (nakahiga), volar (forelimb) or plantar (hindlimb) part is uppermost Supination - turning toward the supine position  VETA 50: OSTELOGOY OSTEOLOGY – study of bones OSTEO – bones BONES Bones are hard materials that are composed of organic and inorganic component. TYPICAL STRUCTURE OF THE BONE Organic component – carbon atoms COLLAGENOUS MATRIX – organic component of the bones, it is a matrix of tissue composed of collagen; a type of protein Inorganic component – no carbon atoms HYDROXYAPATITE CRYSTALS OF CALCIUM PHOSPHATES – inorganic component of the bones The matrix looks like a gauze, it provides the structure of the bone. The inorganic components would provide the material (nasa loob siya). ZONE 1: Zone of reserved cartilage Disproportion of the bone ratio would cause the following: This zone is still composed of pure cartilage 1. OSTEOMALACIA – bone softening ZONE 2: Zone of cell proliferation Bumababa ‘yung inorganic component ng bones This cartilage will proliferate or multiply greatly 2. OSTEOPOROSIS – bone brittling ZONE 3: Zone of cell hypertrophy Bumababa ‘yung organic component sa bone The cells will get bigger They are still cartilage; they are called FUNCTIONS OF THE BONE CHONDROCYTES 1. Supporting and protecting framework of the body Mitosis stops; there are changes on the cellular 2. As levers for muscle action, to change position of matrix of the chondrocytes force and fulcrum Chondro—pertains to cartilage, Osteo—pertains to The bones of the limbs are jointed, there is bones, Osteocytes—bone cells movement in between of those structures. ZONE 4: Zone of Calcification 3. Storehouse for calcium, phosphorous and other There will be deposition of calcium elements in small amounts ZONE 5: Zone of Bone Deposition 4. Blood cell formation Its function is from the bone marrow which can be Chondrocytes will die and will be replaced with found inside the bones osteocytes INTRAMEMBRANOUS - forms directly from the CLASSIFICATION OF BONES mesenchyme ORIGIN All cells of the embryo are mesenchyme ENDOCHONDRAL BONE FORMATION - forms from They are open cartilage models. Mesenchyme cells directly develop to osteocytes Bones start as a cartilage then eventually ossify to become a bone. (Usually true for long bones) We will see the calcium deposition in between the epiphysis and the diaphysis known as the epiphyseal plate. EPIPHYSEAL PLATE – this is where the bone grows e.g., Bones from the base of the skull SHAPE 2. SHORT BONES 1. LONG BONES Compressed rods Long bones are termed as “ossa longga”- long They are termed as “ossa brevis” bones “Brevis” – short “Ossa” – bones, “Os” – bone Parts of a Long bone: Carpal and tarsal bones - each have 7 bones 2 epiphyses (proximal and distal) Cuboidal or irregularly compressed rods 1 diaphysis (shaft of the bone) Parts: diaphysis, metaphysis, epiphysis, epiphyseal plate, Tarsal bones or cartilage Ankle bones Ends of long bones enter formation of freely movable joints Indentations (grooves) are produced by blood vessels, nerves, roughened elevations or depression produced by attachment of tendons and ligaments Ends are enlarged and smooth They have numerous facets (the smooth surfaces of the bone) and they can be Epiphyses have attached to other bones. rounded projections because they serve as the contact points of the joint. These are usually found in freely movable joints such as the head of the humerus 3. SESAMOID BONES and the condyle (distal “ossa sesamoida” part). Found near freely moving joints e.g. in tendons, in ligamentous tissues where tendons pass Sesamoid bones protect tendons at places where greatest friction is developed They look like sesame seeds There is an indentation or groove on the bone, that is where the blood vessels are seen; supplying the areas of the bone. e.g., Patella (kneecap in humans) It has rounded edges It is convex on its dorsal side Concave on its ventral side There are also They are usually found rough portions on the in freely movable joints bone, they serve as the muscle or tendon They are embedded attachments. within the tendons The function of the sesamoid bones is to relieve the pressure from friction.  The patella resides on Frontal bone the groove of the femur. 4. FLAT BONES Limb girdles, flat bones of the cranium consist of outer and inner tables of compact bone and an 5. IRREGULAR BONES intermediate uniting spongy bone, the diploe “ossa irregulare” For muscular attachment, surround and protect There are many jotting processes in its bones sense organs and brain Paranasal sinuses are formed by growth of bone tables that subsequently invade the diploe; pneumatic bones are bones that contain air cavities Termed as “ossa plata” e.g., SCAPULA There are many irregular bones in the skull, especially in its ventral surface. STRUCTURE *It has various structures that arise from it which serves DIFFERENT STRUCTURE OF BONE TISSUES as sites for muscular attachment such as its angles and 1. CORTICAL BONE the big structure in the middle; the spine. Compact, hard bone It is composed of concentric layers of tissue Another example of flat bone is the SKULL. known as the LAMELLA/LAMELLAE Functional unit of bone – Osteon Osteon is composed of concentric layer of lamellae Majority of the bones in the skull are composed of flat bones. We can see sutures on the skull 2. SPONGY/TRABECULAR BONE or site of bone It is composed of trabecula attachment. Trabecula – looks like sponge, there are spicules, Parietal Bone osteocytes have irregular deposition. Pink – Bone Tissue Much softer than the cortical bone  POSITION The skeleton of the bones can be divided into 2: 1. AXIAL SKELETON – group of bones found in the axis of the dog Ventral aspect of the skeleton of the dog (nakatayo) The bones that are In some bones, such as flat bones, these two structures encircled with the red line is are present composing a sandwich. the axial skeleton. Diploe Usually found in the bone of the skulls MECHANICAL CONSIDERATIONS OF BONE Property of bones – strength 2. APPENDICULAR SKELETON Strength – amount of strain a bone can withstand without Bones that breaking made up the limb of the dog are known There are different types of strength of a bone according as the to the forces acting upon it. APPENDAGES. 3. HETEROTROPHIC BONE – either axial or appendicular Only found in males It is called the os penis; the penis of the dog is reinforced with a bone ASSOCIATED STRUCTURE OF THE BONES The strongest strength of a bone is the COMPRESSION STRENGTH. “against its grain” Compression strength – strength against the compressive strain This strength is against the long axis of the bone. Tensile strength – ½ of compression; comparable to tendons & ligaments Sheer strength – ¼ of compression; most fracture is the All the extent of the bone is covered by a mucus result of shear forces membrane called PERIOSTEUM. We can see this in the extremities of the bone Peri – all surface Periosteum - covers non-articular surface of all bones; Bones are designed to provide adequate strength with a divided into outer fibrous and inner osteogenic layer minimal material (minimal mass or weight). LAYERS OF PERIOSTEUM a. HEAD a. FIBROUS LAYER It gives the structure of the periosteum b. OSTEOGENIC LAYER Inner layer, if there is a fracture on the bone, this will be the source of the repair cells When we do surgery, we must return the periosteum, especially the inner layer. Inside the bone, we can find the marrow/medullary cavity The head of the femur that is lined by a tissue called ENDOSTEUM. Spherical projection (head of femur) It has a rounded projection which participates in ENDOSTEUM - lines medullary cavities, condensed the articulation of bones peripheral layer of the bone marrow b. CONDYLES There is another specialized lining in the bone that is usually find in the bone sinuses. The distal ends of the femur and humerus are known as CONDYLES. Bone sinuses – air spaces within the bone such as the More or less cylindrical mass; resemble a pair of frontal sinuses of the dog. knuckles (e.g., condyles of distal femur) MUCOPERIOSTEUM – the lining on the bone sinuses; it They resemble a pair of knuckles; rounded is part of the nasal cavity of dogs. projection Covers bones forming boundaries of respiratory c. TROCHLEA or digestive system and lines all paranasal sinuses. Exostoses occur when the broken part of the bone is over-repaired with bone of poor quality. EXTERNAL FEAUTURES OF BONES Surface contour of bones has irregularities (projections and depressions) which may either be articular or non- The other side has a raised structure which articular resembles a pulley known as TROCHLEA Trochlea – a pulley-mass found in the distal end They are classified into 2: of femur and humerus; this is where the patella 1. PROJECTIONS – raised structures, process, slides. pointy structure, or convex 2. DEPRESSIONS – depressed structures; d. FACETS lowered, concave flat surface found between adjacent carpal/tarsal These classifications can be further divided into 2 bones according to their function: It resembles the head, but smaller a. ARTICULAR – they participate in joint formation Part of joints; bone to bone attachment 2. NON-ARTICULAR PROJECTIONS IN A BONE b. NON-ARTICULAR – muscle and other tissue a. PROCESS/PROCESSES – pointed, bony attachments structure (e.g., spinous and transverse process of vertebra) CLASSIFICATION OF THE EXTERNAL FEAUTURES OF BONES Vertebra has a lot of 1. ARTICULAR PROJECTIONS IN A BONE – bony projections raised surfaces in the bones which participate in It has a spinous, the formation of articulation or joints. transverse, mammillary, and articular processes They serve as muscle attachments  f. NECK – cylindrical part of where head is attached The spinus process is Attaches the head to the epiphysis of the long found in the middle (left side bone of the picture) Some muscles are still attaching their tendons on the neck of the femur b. TUBEROSITY – large rounded non-articular projection (e.g., lateral tuberosity of humerus) e. LINE – small ridge or mark on a bone; straight c. TUBERCLE – small rounded projection structures Trochanter (specific in the femur) – bony mass found in the bones; they are rounded projections that do not participate in articulation Lateral line of the femur Greater tuberosity or tubercle of the humerus Greater trochanter of the femur Tricipital line This is where triceps muscle originates d. SPINE – a pointed prominence on a bone (e.g., 3. ARTICULAR DEPRESSIONS spine of the scapula) a. GLENOID CAVITY – shallow articular depressions or concavity Spine of the e.g., Scapula scapula It is long compared to process Site of attachment of muscles e. CREST – sharp ridge For muscle and ligament attachment b. COTYLOID – deep articular depression (acetabulum of the hip joint) Nuchal crest e.g., Hip bone This where the nuchal ligaments originate; supports the head when it is up  c. NOTCH – articular indentation d. CANAL – tunnel through one or more bones e.g., Ulna e.g., Vertebral Canal – union of different vertebral foramen Radial Notch - If the different vertebra unites, a canal will be formed at The radius will articulate the end. This is now where the spinal cord resides. here 4. NON-ARTICULAR DEPRESSIONS a. FOSSA/FOSSAE – large non-articular depression (e.g., infraspinous fossa of scapula) e.g., Trochanteric or Intertrochanteric Fossa – it is in BLOOD VESSELS AND NERVES between two trochanters 1. Nutrient or medullary artery and vein – serves the marrow passing through the nutrient foramen and canal In long and short bones, these terminate into epiphyseal plates and anastomose with branches from periosteal vessels, in young animals, they end in capillaries. 2. Periosteal artery and vein – supply extremities of long and compact bones 3. Lymph vessels – found in the periosteum as perivascular sheaths 4. Nerves are primarily sensory BONES COMPRISING THE CANINE SKELETON AXIAL SKELETON skull and hyoid – 50 vertebral column – 50 ribs and sternum – 34 APPENDICULAR SKELETON pectoral limb – 90 The humerus has 2 fossae in its distal region: pelvic limb – 96 Olecranon fossa: cranial surface Radial fossa: caudal surface HETEROTROPIC SKELETON os penis – 1 These fossae will unite to form a singular structure. If the ___ fossa has a hole, it is now a FORAMEN. 321 b. FORAMEN – hole/perforation in bone (e.g., foramen magnum, nutrient foramen) The hole at the end of the skull (caudal side) is known as the FORAMEN MAGNUM. c. FOVEA – small non-articular depression e.g., fovea capitis on head of femur VERTEBRAL COLUMN Caudal process (postzygapophysis) Function: Protect the spinal cord and roots of spinal faces caudoventrally or laterally nerves, support of the head, attachment of muscles related to body movements Classification of vertebra based on region: 1. cervical BASIC MOVEMENTS OF THE VERTEBRAL COLUMN 2. thoracic 1. Flexion or dorsal arching of the spine 3. lumbar 2. Extension, straightening or ventral arching of the 4. sacral spine 5. caudal or coccygea 3. Lateral flexion 4. Rotation Vertebral formula of the dog: C7T13L7S3Cd20 A vertebral formula consists of the first letter of Typical vertebrae consist of the body, vertebral arch with the word designating each vertebral group a right and left pedicle and lamina, and processes for followed by the digit designating the number of muscular or articular connection. vertebrae in a specific group. All vertebrae except the sacral remain separate 1. BODY and articulate with contiguous vertebrae in Convex cranial articular surface forming movable joints. Centrally depressed caudal articular The three (3) sacral vertebrae fuse to form the surface sacrum (os sacrum). Intervertebral fibrocartilage or disc is located in between adjacent vertebrae Center of the vertebrae has a pulpy VETA 50: ARTHROLOGY/SYNDESMOLOGY nucleus (nucleus pulposus) surrounded ARTICULATION OR JOINT – formed by union of two or by a fibrous ring more bones or cartilage by other tissues Any union or connection of bone to bone via a 2. VERTEBRAL ARCH OR NEURAL ARCH uniting medium Pedicle E.g., The mandible forms a synovial joint with the Laminae – dorsal part of vertebral arch temporal bone, hyoid bone is attached to temporal bone composed of a right and left lamina by cartilage, and sutures are immovable joints between The vertebral arch and body form the bones of the skull. vertebral foramen All foramina concur to form the vertebral TYPES OF JOINTS canal 1. FIBROUS JOINT or SYSDESMOSIS Cranial vertebral notch is shallow Syn – joints, desmo – fibrous Caudal vertebral notch is deep Segments are united by fibrous tissue; this When the vertebrae are articulated, fibrous tissue is known as the COLLAGEN. notches on either side of adjacent As the animal grows old, this tissue ossifies. vertebrae with fibrocartilage form the (nagiging buto, tumitigas, mas nagiging rigid) right and left intervertebral foramina Fixed or immovable joint where the spinal nerves, arteries and No joint cavity veins pass Most are temporary and later ossify with a resulting synostosis 3. PROCESSES When the joint ossifies, it will now be called as Spine or spinous process – the union of SYNOSTOSIS. the right and left lamina Types: Transverse processes projects laterally a. SUTURES – found in the bones of the skulls; In the cervical region, the transverse joints in the skull foramen divides the process into dorsal When the dogs are neonates (pup pa lang), and ventral parts magkakahiwalay pa ‘yung bones and they’re o Dorsal part is an integral part of being united by sutures. the transverse process e.g., the transverse process of the thoracic vertebrae o Ventral part is homologous to a rib Articular processes are present in the cranial and caudal surface at the junction of the root and lamina Cranial process (prezygapophysis) faces craniodorsally or medially  As they grow old, nago-ossify na ‘yung sutures 2. CARTILAGINOUS JOINT or kaya rigid na sila. SYNCHONDROSIS Fontanelle (technical term) or Bunbunan – in Uniting medium = cartilage between the frontal, temporal, and parietal bones United by fibrocartilage or hyaline or a of a baby; movable pa combination of both Types: a. INTERMANDIBULAR SYNCHONDROSIS (hyaline cartilage joint) – temporary – cartilage is converted to bone before adult life Made up of hyaline Kapag tinamaaan sa ulo ‘yung animals, pwede maputol or mabiyak ‘yung kanilang mandible Mandibles are composed of 2 halves b. SYNDESMOSIS – uniting medium is white fibrous or elastic tissue or a mixture. Connecting medium in between the ulna and radius. e.g., Epiphyseal plate, basilar part of occipital bone with This type of joint would still give small amount of body of basisphenoid, petrous temporal bone and movement in the radius and ulna because this stylohyoid, costochondral junction, intermandibular union will never ossify. synchondrosis o Shafts of metacarpals o Attachment to each other of costal b. SYMPHYSIS (FIBROCARTILAGINOUS) – cartilages contiguous bones are united by fibrocartilage o When opposed ends are united by during some phase of their existence fibrous tissue e.g., fusion of radius and Type of cartilage – fibrocartilage; combination of ulna in the fibrous materials and cartilaginous material o Horse, the original material undergoes e.g., pelvic symphysis, sternebrae, joints between bodies ossification with age (synostosis) of vertebrae Pelvic Symphysis - Mas movable siya especially in parturition (panganganak) - Some hormones released into the system would lead to the softening of the pelvic synthesis para mas bumuka siya at mas lumaki ang pelvic outlet c. GOMPHOSIS – applied to the implantation of teeth into alveoli Fibrous tissue uniting the tooth’s structure Alveolus of mandible – socket kung saan nakadikit ‘yung tooth Joints between bodies of vertebrae Vertebra is connected via the intervertebral disk; it is made up of cartilage It gives more movement compared to fibrous tissue  3. SYNOVIAL JOINT (DIARTHRODIAL) That is a problem in geriatric animals Presence of a joint cavity known as synovial joint (matatanda), mabagal na mag-repair ang capsule articular cartilage nila; mas mabagal na sila A joint cavity with synovial membrane in joint gumalaw kasi masakit na mga joint nila. capsule is present *Crunchy part ng paa ng manok A movable joint It is movable because it has a cavity and a lubricating medium inside it. It is filled with SYNOVIAL FLUID. Synovial joint can either be SIMPLE or COMPLEX SIMPLE – union between 2 bones; COMPLEX – more than 2 bones participate in the formation of the joint cavity Simple joints are formed by two articular surfaces Composite joints are formed by several articular surfaces c. ARTICULAR CAPSULE A tube with its ends attached around articulating surfaces. Externally it is made up of fibrous tissue, its internal surface is lined by synovial membrane. It connects the two moving bones which encloses that joint cavity to have room between them. This room/cavity is filled with a lubricating medium known as the SYNOVIAL FLUID. SYNOVIAL FLUID – composition is similar to ESSENTIAL STRUCTURES OF SYNOVIAL JOINT tissue fluid plus albumin, mucin, salts; it is alkaline a. ARTICULAR SURFACE – smooth, dense bone and contains mucous cells. Made up of dense tissue or material Function: Lubricates the joints, transport nutrient Cortical in structure materials to hyaline articular cartilages If there will be motion between the 2 bones, it It is enclosed by the joint capsule should be smooth It makes the motion between the joints easier Some bones have more than 1 articular surfaces, especially in the carpal joints This articular surface is being protected by an ARTICULAR CARTILAGE. 2 layers of the joint capsule: 1. OUTER FIBROUS LAYER – which makes the capsule rigid 2. SYNOVIAL MEMBRANE (inner layer) – capable in producing the synovial fluid b. ARTICULAR CARTILAGE Covers articular surfaces of bones, non-vascular, As the animals grow old, the production of smooth with bluish tinge in the fresh state synovial fluid will slow down. (carcass), decreases effects of concussion and In some cases, the synovial fluid is filled with friction different types of salt. The cartilage is softer than the bone o Urate crystals The cartilage can receive pressure when the joint o E.g., Dalmatians have problematic joints is in motion when they grow old kasi nagkakaroon Without the articular cartilage, movement will be sila ng problem sa kanilang uric acid painful metabolism. Hindi nare-release ‘yung It serves as a padding or insulation to movement uric acid kaya nagkakaroon ng buildup. There is easier repair in cartilage than the bone o The uric acid builds up in the joint cavity as urate crystals.  o Gout in humans Lateral and medial meniscus in dogs d. LIGAMENTS – strong membranes of white The condyles are sitting on them in the tibia fibrous tissue which binds bones together. They can absorb pressure because they are Its structural integrity resembles the tendon. made of fibrocartilage tissues Difference: Tendon – attachment of bone to Problems of meniscus: Meniscal tear muscle; Ligament – attachment of bone to bone Ligaments according to their location: INTRACAPSULAR – ligament found inside the capsule e.g., Cranial cruciate ligament and Caudal cruciate ligament - Found in between the condyles of the femur and articular surface of the tibia. - Humans: Anterior and Posterior cruciate ligament (ACL, f. MARGINAL CARTILAGE PCL) A ring of fibrocartilage encircling the rim of an articular cavity to prevent fracture of the margin. Found in between the articular cartilages EXTRACAPSULAR – ligament found outside the capsule e.g., Patellar Ligaments g. VESSELS AND NERVES Synovial membrane is closely associated with capillaries, veins form plexuses, well supplied with lymph vessels, nerve fibers. Para magka-supply ang synovial fluid, dapat may blood vessels na nagsu-supply sa joint. COLLATERAL – located on sides of a joint TYPES OF MOVEMENTS IN JOINTS INTEROSSEUS – connects directly apposed 1. GLIDING – one surface gliding over another surfaces of bones 2. ANGULAR a. FLEXION – angle between two bones e. ARTICULAR DISCS AND MENISCI/MENISCUS decreases Plates of fibrocartilage or dense fibrous tissue b. EXTENSION – straightening at a joint placed between articular cartilages. c. ABDUCTION – a part is moved away Divides the joint cavity into two compartments. from the midsagittal plane of the body Allows a range of movements d. ADDUCTION – a part is moved toward Decreases concussion the midsagittal plane of the body 3. ROTARY a. CIRCUMDUCTION – bone is made to circumscribe a conical space; quadrupeds can move in this manner to a limited degree  b. ROTATION – rotation of one segment 3. SPHEROID OR ENARTHRODIAL JOINT – ball around the longitudinal axis of the other & socket joint segment forming the joint, e.g., atlanto- Moves in almost all directions (flexion, extension, occipital joint hyperextension, circumduction, abduction, o PRONATION - rotation of adduction) extremity so that the dorsum is Head of 1 bone fits in the depression of the other up bone o SUPINATION - rotation of e.g., Hip joint extremity so that the palmar or Head of the femur; socket: cotyloid cavity or plantar aspect is up acetabulum Spherical in structure and is enclosed in a socket TYPES OF SYNOVIAL JOINTS Fixed by strong ligaments so it won’t pop out 1. GINGLYMUS OR HINGE JOINT - moves in the sagittal plane (extension, flexion, hyperextension) Resembles the hinges of the door e.g., Fetlock jt. There are conditions that there will be a problem on the mechanism of the hip joints Hip dysplasia – common in German shepherd Elbow joint 4. CONDYLAR JOINT - like hinge joint but with more movement (flexion, extension, lateral) Formed by condyles e.g., Temporomandibular joints 5. ELLIPSOID JOINT - char. by an articular surface expanded more in one direction than another Its contact surface is shaped like an ellipse e.g., Joint between distal end of radius + proximal row of carpal bones Confined to 2 principal movement (flexion, extension) 2. ARTHRODIAL (PLANE) JOINT - joint with slight gliding movement between relatively flat apposed surfaces. Glides on 1 plane e.g., Joints between adjacent carpal bones 6. SADDLE JOINT - joint with an english or flat saddle-shaped articular surface; perform all movements except rotation. The previous bone is sitting on the next bone Its motion is confined on a sagittal plane; minimal extension and flexion e.g., carpometacarpal joint of humans, interphalangeal joints of dog These bones have minimal movement due to the facets of the carpal bones.  Pastern joint of the phalanges The middle phalanx sits directly on the distal 3. SKELETAL MUSCLE - multinucleated fibers that phalanx terminate by attaching to connective tissue Shape – elongated Placement of nucleus – multiple, VETA 50: MYOLOGY periphery Myo – muscles; Myology – study of muscles Function – voluntary Presence of striations – present Muscles have the property of CONTRACTILITY and CONDUCTIVITY. CONTRACTILITY OR CONTRACTION – any muscle cell has a property of length and it has the ability to shorten it, producing work and force. o However, it cannot produce work and force without the presence of bones and joints. CONDUCTIVITY OR CONDUCTIVE – muscles can conduct electricity o In muscle physiology, the principles of Muscular tissue is composed of muscle fibers/myofibers. It serves as the structural unit of the muscle and assemble muscle contraction are governed by the an individual cell. electricity. o Also same with the nerves Each muscle fiber is covered by a connective tissue Instead of cells, muscles consist of fibers because of their known as ENDOMYSIUM. arrangement. They are bundled together to form a muscle CLASSIFICATION OF MUSCLES FASCICLE/bundle. This bundle moves in unison. 1. SMOOTH MUSCLES - spindle-shaped cells in The muscle fascicle is covered by a connective walls of hollow organs and blood vessels, glands, tissue known as PERIMYSIUM. eyeball, hair follicle, produces weak rhythmic but These muscle fascicles are again collected to sustained contractions, involuntary form the individual muscle. This muscle is Shape - spindle covered by a connective tissue called Placement of nucleus – single, centrally EPIMYSIUM. located A bundle surrounded by perimysium and the Function – involuntary, they move on entire muscle by epimysium. their own not on our conscious control Presence of striations – No striations Endomysium covers the muscle fiber/myofibers, perimysium covers the muscle fascicles, and the epimysium covers the muscle itself. 2. CARDIAC MUSCLE - with cross-striations, involuntary Shape – branched Placement of nucleus – single, centrally located FASCIA – connective tissue separating muscles Function – involuntary from each other and binding them in position; Presence of striations - present  depending on their location, can be superficial or e.g., Triceps brachii – it has 4 origins, each origin is deep fascia. termed as the HEAD. It covers the muscles aside from the epimysium. If it has more than 1 insertion, it is now called as 2 layers: TAIL. 1. DEEP – composed of fibrous connected tissue, dense, strong, rigid. (Deeper than the superficial, A muscle would be able to produce work, force, nakadikit sa epimysium) or its own strength if it’s able to traverse (travel 2. SUPERFICIAL – relatively loose. In some well- across or through) one joint. conditioned animals, this loose connective tissue The triceps brachii originates from the humerus is filled up with ADIPOSE TISSUE. and inserts in the ulna, it traverses one joint. Sometimes it is called as HYPODERMIS – serves as the adipose bank of an animal, Fat found under the skin. PARTS OF A MUSCLE A muscle is typically elongated. If the belly would contract, there will be motion in the insertion. (It is more movable in the origin) The movement is the extension of the elbow. APPEARANCE BASED ON ARRANGEMENT OF FIBERS 1. STRAP MUSCLE (PARALLEL FIBERS) e.g., Triceps brachii, medial head Their fibers and parallel to each other and they It has a proximal and distal end. are directly perpendicular to their attachment. Proximal attachment is known as the ORIGIN. Usually found in the superficial layer of muscles Distal attachment is known as the INSERTION. Thin; only moves in one direction. In between them, the muscular part, is known as the MUSCLE BELLY – fleshiest portion of the muscle. The strength of the muscle is directly proportional to the diameter of the muscle belly. Mas kumakapal ang muscle belly, mas tumataas ‘yung strength ng muscle. In some cases, there are muscles with 2 bellies. It is called DIGASTRICUS. This muscle digastricus is the only muscle that opens the mouth. e.g., Sartorius muscle (it looks like a belt found in the medial side of the thigh) The insertion is much more movable than the origin. The origin is fixed. Sometimes, the origin can be described as the HEAD OF THE MUSCLE when there are more 2. PENNATE MUSCLE than 1 origin for the muscle. Their origin and insertion are at an ANGLE. Stronger and thicker  Still in a singular direction - UNIPENNATE MULTIPENNATE More than 2 muscle fiber directions Seen in animals with fully functional digits; dogs cannot control their individual digits (toes, fingers). e.g., Semimembranosus, Semitendinosus of the hind limb Humans can control their individual digits, our extensors have multipennate belly. 3. FUSIFORM BIPENNATE The thickest part of a muscle is the belly. An Two directions intermediate tendon produces two bellies The muscle belly is being traversed by an (digastric). additional tendon (accessory or secondary). To produce skeletal movements, the muscle must traverse at least one joint. o Muscles in association with superficial fascia move the skin o Sphincters surround a natural body orifice o Constrictors are arranged on walls of tubes or cavities Origin – attachment of muscles which remain stationary during movement, the opposite is its insertion. In the limbs, the origin is the proximal attachment while the insertion is the distal attachment. e.g., Biceps brachii Lacertus fibrosus – accessory tendon of the biceps brachii Groups of muscles combine their effort to produce a characteristic movement. These muscles are called However, in dogs, it is incomplete but it still PRIME MOVERS OR AGONISTS. makes the muscle fiber bipennate. An ANTAGONISTIC MUSCLE opposes In other larger animals, such as horses and movements produced by agonists. ruminants, the lacertus fibrosus is fully functional and it would traverse all of the biceps brachii. The action of a muscle or group of muscles on a joint depends on their location relative to a joint. Extensors are on the side of a hinge joint where contraction will align the bones or straighten the limb.  Flexors cross the surface where the smaller angle Counterpart: Antagonist – flexor muscles, flexion between bones are formed. muscles (makikita sa kabilang side ng bones) Tendons are bound to the limb by annular ligaments RETINACULUM or ANNULAR LIGAMENTS – belt-like (retinacula). If there is much movement or change in structures which fix the muscles on their location. direction over a joint, the tendon is surrounded by a Fixes the muscles and their tendons on their synovial sheath. location. These tendons are found in the specific grooves If limited movement but pressure exists against a part of along the bone. the long bone, a bursa occurs between tendons and bone. If they move, they will slip causing sprain. The retinaculum prevents it. Aponeuroses are thick sheets of connective tissue that serves as origin or insertion to muscles. STRUCTURES OF MUSCLES CONCERNING THEIR MOTION AND MOVEMENT DEEP FASCIA e.g., Antebrachial Fascia – holds the different muscles that is found in the cranial region of the radius. TENDONS - join skeletal muscle to bone Function: Transmit force in one direction, and act as shock-absorbers May pass through groove or sheath Golgi tendon organs: Special nerve endings: measure force (stretch?) Outer sheaths: White; random collagen; many fibroblasts - epitenon, epiligament Insertions: Blend with periosteum; some penetrate bone; folding at myotendinous junction Their function is for EXTENSION. The cranial portion of the radius has different Continuous from the connective tissue of muscles muscles (4: Extensor carpi radials, Ulnaris Rope like structures that are composed of Dense, lateralis, Extensor digitorum lateralis, Extensor White, Fibrous Connective Tissue (DWFCT). digitorum communis) – they have extension EPITENON - connective tissue that covers the movement tendon. To make their movement efficient, the body covers it with an antebrachial fascia; kapag nag- They have small blood supply; any injury to the move ang isa, magmu-move na rin lahat. tendons will lead to slow recovery. I will not go back to its pristine condition. Tendons are made from fibers. Any fracture of those fibers, the body won’t put it back again, papatungan lang ng additional fibers. Pwede magkaroon ng bundles doon sa structure. May possibility na mag-rupture ulit siya if ‘di maganda ang rehab. Tendons have stretch receptors: GOLGI TENDON ORGANS – sends signal to the brain to recoil the muscle so the tendon won’t rupture. Some muscles would have their tendons as roofs (cylindrical) e.g., Tendons of Anterbrachial Some tendons are sheath instead of rope-like ECLU – agonists of the digit extension; principal (malapad) agonist Known as APONEUROSIS or WHITE TENDON e.g., The tendon of the External abdominal oblique CONDUCTING PORTION Involved in the taking and releasing of air. Passage of air o Conduct air from outside environment of the dog towards the respiratory portion (lungs). o Composed of the EXTERNAL NARES, NASAL CAVITY, PHARYNX, LARYNX, TRACHEA, and the BRONCHIAL TREE. Modify and regulate air o Humidify, removes foreign objects etc. o The air that enters the body must be humidified because moist air has more oxygen. VETA 50: SPLANCHOLOGY o It is done by the turbinates found in the nasal cavity of the dog. ORGANOLOGY – study of the different visceral organs. ▪ TURBINATE – scroll-like structures composed of bones. CLASSIFICATION OF VISCERAL ORGANS IN DOGS ▪ These bones are lined with 1. PARENCHYMATOUS ORGAN mucus membrane which Has parenchyma, that is why when we touch secretes MUCIN OR MUCUS. these organs, they’re firm. ▪ The mucus gives humidity to the It has a fibrous envelope known as the stroma. incoming air. o STROMA – makes up the dense fibrous ▪ Turbinates also filter the air that connective tissue which covers the whole goes inside the conducting surface of any parenchymatous organ. portion (The bones look like a Made up of tissue. mesh). E.g., Liver ▪ The lining epithelium of the turbinates are ciliated, improving 2. TUBULAR ORGAN the filtration of air. A tubular organ has a lumen and a wall. Site of olfactory receptors o LUMEN – the space inside the tubular o The nose of the dog is more powerful organ. than that of a man. E.g., Bloodhounds’ Looks like a tube. nose is 10x more powerful. The wall of a tubular organ is composed of o The scent receptors known as different layers known as TUNICS. ETHMOTURBINATES are embedded in All tubular organs have 4 LAYERS: the mucus membrane of the nasal cavity a) TUNICA MUCOSA or the MUCUS of the dog. LAYER o The larger the nasal cavity of a dog, the b) TUNICA SUBMUCOSA – layer after the more powerful their sense of smell is. tunica mucosa Facilitate heat and water exchange c) TUNICA MASCULARIS – muscular o Dogs have non-functional sweat glands; layer meaning, they do not sweat. d) TUNICA ADVENTITIA – fibrous material o Dogs PANT to relieve their heat. They also put their tongue outside to release heat from their mouths. o They also release heat through INCREASE VASCULARIZATION of the nasal cavity. o Habang mas dumadami ‘yung daan ng air sa nasal cavity and mas mababa ‘yung temperature ng air compared sa blood, nare-release nila ‘yung heat from the blood. Make phonation/sound production possible o True for dogs because of their larynx. o ARYTENOID CARTILAGE - a cartilage RESPIRATORY SYSTEM that acts like a reed. It would vibrate In general, the system is made up of two portions: the when air flows through out. It is the conducting and the respiratory portions. ▪ This cartilage has the vocal process.  ▪ Vocal process vibrates when air CIRCULATORY SYSTEM moves through it. (barking) Circulate the blood of the dog. RESPIRATORY PORTION ORGANS PRESENT IN THE CIRCULATORY SYSTEM Involved in exchange of gases, CO2 to O2. 1. HEART o This will only happen in areas from where 2. ARTERIES a respiratory membrane is present. 3. VEINS o It is found in the alveoli of the lungs. Since all these organs are composed of blood, their structure is tubular. LAYERS OF THE RESPIRATORY MEMBRANE FROM THE ALVEOLUS DIFFERENT TYPES OF CIRCULATION a) SQUAMOUS EPITHELIUM – the alveolus is 1. PULMONARY CIRCULATION – circulation from lined by this membrane. where oxygenation happens. b) BASEMENT MEMBRANE OF THE SQUAMOUS Unoxygenated blood is oxygenated. This EPITHELIUM happens in the lungs. c) BASEMENT MEMBRANE OF THE Main blood vessel involved: PULMONARY ENDOTHELIUM ARTERIES AND VEINS – pulmonary arteries d) ENDOTHELIUM OF THE CAPILLIARIES carry unoxygenated blood towards the lungs while the pulmonary veins carry the oxygenated blood from the lungs back to the heart for general circulation. 2 types of circulation: VASA PUBLICA – blood circulation that moves along an organ but it is not used by that organ. o It only filters the blood and is not used for its organ’s nourishment. o E.g., pulmonary arteries and veins VASA PRIVATA – the blood supply that is used for the organ’s nourishment. o E.g., vasa private of the lungs – blood vessels that supply the lungs known as the BRONCOESOPHAGEAL VESSELS. o This vessel gives nourishment to the lungs. 2. CORONARY CIRCULATION – vasa private of the heart, the only blood supply of the heart. Heart is the organ that pumps blood throughout the body, but it also needs its own nourishment. It is provided by the CORONARY ARTERIES (left and right) and being drained by the GREAT CARDIAC VEIN. 3. PORTAL CIRCULATION – blood drained from the intestines Blood from intestines is shunted to the liver for filtration and bio metabolism. o The alveolus is well vascularized. It has a lot of E.g., carbohydrates – they are absorbed as a capillaries and they contain the blood. disaccharide or monosaccharide. However, o Because of the partial pressure of oxygen and glucose is the only carbohydrate that is used by carbon dioxide, the pressure of the carbon the cells of the body. dioxide is greater than the veins. o Other carbohydrates should be o As stated sa theory of diffusion, lalabas ‘yung converted to glucose before putting them carbon dioxide sa air at papasok naman ‘yung sa into the systemic circulation. oxygen kasi mas mataas ang oxygen sa air at E.g., alcohol – if we don’t have a liver, our mas mababa sa blood ng veins. (Exchange of intestines would absorb the alcohol and will then oxygen and carbon dioxide). enter our systemic system leading to death. Actual air exchange.  4. SYSTEMIC CIRCULATION – the blood from the effector organ going to the heart for oxygenation then back to the effector organ. a) SYSTEMIC ARTERIES b) SYSTEMIC VEINS DIGESTIVE SYSTEM The digestive system consists of a musculomembranous tube extending from mouth to anus. It functions for ingestion, rendering, digestion and absorption of food, and elimination of solid wastes. It is composed of a canal known as the ALIMENTARY CANAL – its opening is the buccal cavity and its exit is the anus. o Made up of tubular organs LAYERS OF THE TUBULAR ORGAN (DIGESTIVE) a) TUNICA MUCOSA – some tunica mucosa of the digestive system, especially the intestine, have VILLI/VILLUS. Alimentary canal is supported by ACCESORY GLANDS: o VILLI – folds in the intestines. It a) SALIVARY GLANDS – mandibular, parotid, increases the surface area where sublingual and zygomatic (only in the dog and nutrients are absorbed. cat) b) TUNICA SUBMUCOSA – contains reticular b) LIVER INCLUDING THE GALL BLADDER issues c) PANCREAS o It also contains some immune cells which fights infection. (intestines are non- URINARY SYSTEM sterile) The ultimate function of the urinary system is the filtration o Defense of digestive system of blood and elimination of harmful wastes. It is generally c) TUNICA MUSCULARIS – composed of smooth composed of a filtration organ, organ for storage of urine muscle cells. Their primary function is for and means to transport and eliminate urine from the body. PERISTALSIS. In dogs, their filtration organ is the KIDNEYS. It o PERISTALSIS – moving the food from filters out the blood that’s why it has a great the alimentary canal towards the anus. vascularization. d) TUNICA ADVENTITIA OR SEROSA – fibrous The URINE is formed to the kidneys. It will then tissue that covers the tunica muscularis. be transported to the storage organ, which is the BLADDER, by the ureters. Some visceral organs are found inside the cavity of an The excretory organ known as the EXTERNAL animal. It can either be the thoracic or abdominal cavity. GENITALIA (penis&vulva) of the animals house These cavities have a MESOTHELIUM covering it. the URETHRA of the urinary system. In the thoracic cavity, the mesothelium is known as the THORACIC PLEURA. REPRODUCTIVE SYSTEM In the abdominal cavity, it is known as the One cardinal function of a living organ is the ability to ABDOMINAL PERITONEUM. procreate or reproduce. This is the primary function of the reproductive system. It consists of a primary reproductive The mesothelium has 2 layers: organ, a reproductive tract, and accessory organs a) PARIETAL PLEURA AND PARIETAL (external genitalia). PERITONEUM The reproductive organ is usually known as the b) VISCERAL PLEURA AND VISCERAL GONADS. PERITONEUM Reproductive organ of males – TESTIS; from the testis, the gametes or the spermatozoa is All of the visceral organs inside these cavities are covered transported towards the external genitalia by a by mesothelium. It is possible that the tunica adventitia long reproductive tract. will be covered by a mesothelium if the organ is in the o The male reproductive tract would exit thoracic cavity, such as the esophagus; its outermost the body via ejaculation from the penis, layer will be the visceral pleura of an esophagus. But it which is its external genitalia. blends with the tunica adventitia and they are collectively Gonads of females – OVARIES; transported by known as the TUNICA SEROSA. the female reproductive tract which is greatly tubular and much shorter than males, then moves to their external genitalia known as the VULVA. NERVOUS SYSTEM FUNCTIONAL CLASSIFICATION OF THE NERVOUS The nervous system has been by custom categorically SYSTEM divided into central and peripheral systems. SOMATIC NERVOUS SYSTEM The central nervous system is defined as o Under our voluntary or conscious control. consisting of the brain and the spinal cord. AUTONOMIC NERVOUS SYSTEM The PNS includes the cranial and spinal nerves, o Under our involuntary control. It can be their ganglia, and peripheral portions of the further classified into 2: autonomic nervous system. ▪ SYMPATHETIC - #fightorflight The neuron is the genetic, structural, functional, mechanism. It is also known as and trophic unit of the nervous system. It is the the THORACOLUMBAR part of fundamental unit of the nervous system from the ANS. The ganglia are found which more complex structural and functional in this region. concepts must originate. ▪ PARASYMPATHETIC - #rest&digest mechanism. It is The functional unit of the nervous system is the neuron. also known as the NEURON – is the principal cells found in the CRANIOSACRAL. The nerve nervous system. There are 2 types of processes cells that contain of a neuron: parasympathetic nerve cells are o DENDRITE – brings the information or found in the cranial nerves and the impulses from outside the cell some of the sacral spinal nerves. towards the NERVE CELL BODY (SOMA). o AXON – brings the information or VETA 50: THORACIC LIMB impulse away from the body towards The thoracic limb of the dog is also known as the another cell which would have dendrites FORELIMB and we can divide it into 4 regions: and axon. 1. SHOULDER 2. ARM/BRACHIUM 3. FOREARM/ANTEBRACHIUM 4. MANUS – terminal segment of the forelimb; the counterpart of the hand of the human. It can be classified anatomically and physiologically: ANATOMICAL CLASSIFICATION a. CENTRAL NERVOUS SYSTEM (CNS) – made up of the brain and spinal cord b. PERIPHERAL NERVOUS SYSTEM (PNS) – composed of the cranial nerves and the spinal nerves; all the peripheral nerves, including nerve trunks, ganglia, that is found outside CNS, then it SHOULDER REGION is considered as PNS. We can only see the SCAPULA in this region. It is the only functional bone. DIFFERENCES OF CNS AND PNS Unlike in humans, the SHOULDER GIRDLE of Regarding their nerve synapses it is termed either: dogs is incomplete. GANGLIA – if it is found in the PNS o The shoulder girdle of humans, frogs, NUCLEUS – if it is found in the CNS and avian consist of 3 bones: Nerve synapses are made up of nerve cell bodies. CLAVICLE, CORACOID, SCAPULA.  o There are no clavicle and coracoid in SKELETON OF THE FORELIMB dogs. In some cases, they are considering the presence of VESTIGE of BONE OF THE SHOULDER the clavicle as part of the shoulder girdle. SCAPULA However, their shoulder girdle has NO It is a flat bone ARTICULATION with the body. Its shape is like a leaf. In some cases, it has a triangular shape. This triangular shape has borders and angles. ARM/BRACHIUM REGION Consists of the humerus o Caudal angle, cranial angle, dorsal border, caudal border FEATURES AND STRUCTURES OF SCAPULA FOREARM/ANTEBRACHIUM ARTICULAR DEPRESSIONS Represented by the radius, which is more cranial,