VNSA3 Flashcards
Define anatomy
Physical structure of the body
Define physiology
Way in which the body systems work
Define ventral
Towards the belly or lowermost surface of the animal
Define dorsal
Towards the back of the animal
Define caudal (posterior)
Towards the rear or tail end of the animal
Define cranial (anterior)
Towards the front or head of the animal
Define Rostral
Towards the nose
Define proximal
Towards the body
Define distal
Away from the body
Define palmar
Rear surface of the front paw
Define plantar
Rear surface of the hind paw
Define dorsal paw
Front aspect of either paw
Define medial
Closer to the median plane or midline of the animal
Define lateral
Away from the median plane or midline of the animal
Define sternal/ventral recumbency
On its stomach
Define dorsal recumbency
On its back
Define lateral recumbency
On its side
Define
Median or sagittal plane
Divides the body into L and R
Define
Transverse plane
Perpendicular to long axis of the body cutting it into front and back
Define
Dorsal plane
Parallel to back cutting into top and bottom
Define
Para-sagittal plane
Parallel to median plane moving more laterally
Define contralateral
Affecting the opposite side
Define ipsilateral
On the same side
Define deep
Closer to the centre of the body
Define superficial
Near to the surface of the body
Define Abduction
Movement away from the medial plane
Define adduction
Movement towards the medial plane
Define protraction and retraction
Protraction = to protrude or stick out a part of the body
Retraction = movement that brings a protracted body part back to its original position
Define supination and pronation
Supination = a motion toward the centre of the body (rolling foot inwards)
Pronation = a motion towards the outside of the body (rolling foot outwards)
What are the 3 body cavities ?
Thoracic
Abdominal
Pelvic
What structures are found within the thoracic
Lungs, heart, diaphragm, oesophagus, trachea, arteries and veins, thymus gland
What structures are found within the abdominal cavity?
Stomach, intestines, kidneys, liver, pancreas, gall bladder, spleen, adrenal gland, ureter and bladder
What structures are found within the pelvic?
Bladder, reproductive organs, colon, rectum, urethra
What does the pleura line
Thorax or thoracic cavity
What does the peritoneum line mean?
The abdominal cavity
What is the pleura and peritoneum?
A serous membrane.
Produces a watery fluid ensuring friction free movement between the surfaces of the cavity and organs/structures within it.
What is parietal and visceral
Parietal = serous membrane lining the boundaries or sides (walls) of the cavity
Visceral = serous membrane covering the organs (viscera) within the cavity
What are the boundaries of the thoracic cavity ?
Cranially = thoracic inlet: first thoracic vertebrae, fist pair of ribs and cranial end of sternum
Caudally = diaphragm
Dorsally = thoracic vertebrae and hypaxial muscles
Ventrally = sternum
Laterally = ribs and intercostal muscles
What is the central space between the thoracic cavity called ?
Mediastinum
Containing: the heart, trachea, oesophagus and major blood vessels
What are the boundaries of the abdominal cavity?
Cranially = diaphragm
Caudally = pelvic inlet
Dorsally = lumbar vertebrae
Ventrally = abdominal muscles
Laterally = abdominal muscles
Define omentum
A lacy sheet of peritoneum from the stomach extending to the caudal abdomen
Define mesentery
The visceral peritoneum associated with the small intestines
What are the boundaries of the pelvic cavity ?
Cranially = pelvic inlet
Caudally = pelvic outlet
Dorsally = sacrum
Ventrally = floor of pelvis
Laterally = lateral walls of the pelvis
MRS GREN
Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition
Levels of organisation (smallest to largest)
Cell, tissue, organ, organ system, organism
Cell or plasma membrane
Provides structure surrounding the cell
Semi-permeable
Approx 8nm wide
Made up of phospholipid bilayer containing protein and carbohydrate molecules
Define free entry
(Semi-permeable)
Some substances can pass through the membrane easily
Define entry via protein transport system
(Semi-permeable)
Some substances can pass through the membrane via the protein transport system, providing some control
Define excluded
(Semi-permeable)
Some substances are prevented from entering the cell
What is passive transport ?
Across a gradient of concentration, pressure or electrical charge, no energy required
What is diffusion ?
Movement of molecules from an area of high concentration to low concentration through a semi-permeable membrane.
Small molecules (O2, CO2, H2O) can pass freely through the pores, same for lipid soluble substances.
What is facilitated diffusion?
Passive movement of large molecules/ions across a semi-permeable membrane, from an area of high concentration to low concentration with the use of proteins
What is osmosis?
Movement of water from an area of low concentration to an area of high concentration through a semi-permeable membrane, when large molecules cannot get through.
What is active transport?
Requires energy to transport molecules (glucose/amino acids) or ions (sodium/potassium) across a cell membrane, against concentration gradient.
Energy is provided by glycolysis.
ATP is converted into ADP, releasing energy
Then used to ‘push’ the substance against the concentration gradient.
What is endocytosis ?
Material taken into the cell
What is exocytosis ?
Material removed from the cell
What can be seen under a light microscope ?
Nucleus, vacuoles, cell membrane, cytoplasm.
What can be seen under an electron microscope?
All cell parts
Lysosomes, Golgi vesicles, ribosomes, RER, SER, cell membrane, cytoplasm, microtubules, centrioles (centrosome), nucleus, nucleolus, Golgi apparatus, mitochondria.
What are somatic cells
All cells in the body except for reproductive cells
Replicate by mitosis and contain diploid number of chromosomes.
What are germ cells?
Reproductive cells - sperm and ova
Replicate by meiosis and contain a haploid number of chromosomes
Mitosis
( I paid my aunt twice)
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
(Mitosis)
Known as the ‘resting phase’
Cells grow and prepare for next division
Chromosomes become more visible
Prophase
(Mitosis)
Nuclear membrane breaks down
Chromosomes replicate
Identical pairs of chromatids remain joined at the centromere
Centrioles move to opposite ends and from spindle fibres
Metaphase
(Mitosis)
Chromosomes line up at the equator of the cell
Chromatids start to pull apart at the centromere
Anaphase
(Mitosis)
Chromosomes attach to the spindle, which then contracts
Chromatids pulled to opposite ends of the cell
Telophase
(Mitosis)
Spindles break down and nuclear membrane reforms
Cell constricts separating into 2 cells
Cytokinesis
(2 identical daughter cells with diploid number of chromosomes, they unravel)
Meiosis
Interphase
Prophase I
Metaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase II
Interphase
(Meiosis)
2 pairs of identical chromosomes
Prophase I
(Meiosis)
Each chromosome replicates, crossing over may occur
Metaphase I
(Meiosis)
Chromatids arrange in pairs along the equator of the cell
Anaphase/telophase I
(Meiosis)
Chromatids migrate to the syncytium poles and the cell starts to divide
(First meiotic division, cytokinesis - 2 identical daughter cells, each containing the diploid number of chromosomes)
Prophase II
(Meiosis)
Transitory, no chromosome replication
Metaphase II
(Meiosis)
Chromosomes arrange themselves along the equator of the cell and fibrous spindles form.
Anaphase II
(Meiosis)
Chromatids migrate to the poles
Telophase II
(Meiosis)
Each cell divides and the nuclear membrane begins to form
(2nd meiotic division - cytokinesis - 4 identical daughter cells form each containing haploid number of chromosomes. These cells are not identical to the parent cell).
Fluid is present in the body in a variety of forms
Define - Intracellular
Inside cells
Fluid is present in the body in a variety of forms
Define - extracellular
Interstitial
Extracellular fluid that surrounds the cells
Fluid is present in the body in a variety of forms
Define - intravascular
Found in the vascular system
(Blood)
Normal water loses for cats and dogs
Urine - 20mls/kg/day
Faeces - 10-20mls/kg/day
Respiration and sweating - 20mls/kg/day
Water requirements
Cats, dogs, rabbits
Cats and dogs - 50-60mls/kg/day
Rabbits - 100ml/kg/day
About the cell membrane
- permeable to small molecules
-larger molecules cannot pass through
-movement of water is controlled by the osmotic and hydrostatic pressure (they oppose each other)
Passive transport - simple diffusion
Water, dissolved gases or lipid-soluble molecules move from an area of HIGH concentration to an area of LOW concentration.
Passive transport - OSMOSIS
Diffusion of water across a semi-permeable membrane from an area of LOW sugar concentration to an area of HIGH sugar concentration to reach equilibrium. The water has to move as the sugar cannot pass through the membrane as it’s too large.
Name the osmotic pressures in the body
Hypertonic
Isotonic
Hypotonic
Define renation
Water leaves faster than it enters
Define lysis
Water enters cells rapidly, can cause cells to burst
Atoms
- have no electrical charge
-if they gain a charge they become ions
-if they lose a charge they become positively charged
-if they gain a charge they become negatively charged
Positive ions
Called cation
(Sodium Na+, potassium K+, calcium Ca+2, magnesium Mg+2, iron Fe+2 and hydrogen H+)
Negative ions
Called anion
(Chloride Cl- , bicarbonate HCO3- , sulphate SO4-2 , phosphate HPO4-2 and protein anions
Electrolytes
Chemicals that dissolve, or split in water forming positive and negative ions (an element that carries an electrical charge)
Help regulate the osmosis of water between water compartments. Some are involved in acid-base regulations
pH levels
pH 7 is neutral
pH greater than 7 is alkaline
pH less than 7 is acid
Normal pH of blood is 7.35-7.45
If pH falls below 7.35 acidaemia exists
If pH is greater than 7.45 alkalaemia exists
Acidosis and alkalosis
Both terms describe abnormal processes and conditions that cause acidaemia or alkalaemia.
Acidosis and alkalosis can exist without acidaemia/alkalaemia bcs of the body’s secondary compensatory mechanisms.
It is essential for proper cellular function that the blood pH is kept within normal range.
The body has various mechanisms for dealing with hydrogen ions that are produced within the body to prevent dramatic fluctuations in pH.
(Buffers, respiratory response, renal response).
Acid-based regulations
Buffering
Buffers react with acids to limit the pH change that they would normally produce.
buffers trap hydrogen (H+) ions, preventing the pH (e.g bicarbonate and phosphate)
These are classed as extracellular buffers
Acid-based regulations
Respiratory system
Carbon dioxide is dissolved in the body fluids as increasing respiration removes carbon dioxide from the body anf therefore raises pH.
Decreasing respiration increases carbon dioxide and therefore lowers pH
Acid-based regulations
Renal system
Bicarbonate (a buffer) can be generated within the cells of the kidney, neutralising H+ ions.
The kidney will also increase the amount of H+ ions that are excreted in urine, removing H+ ions.
Acidosis
Respiratory and metabolic
Respiratory = impaired ventilation, inspired carbon dioxide, increased carbon dioxide production
Metabolic = accumulation of H+, ruptured bladder/blocked urethra, diabetic keto-acidosis, chronic diarrhoea
Alkalosis
Respiratory and metabolic
Respiratory = over ventilation
Metabolic = loss of H+, over administration of sodium bicarbonate
What is a tissue?
A group of similar cells that function together to perform a specialised activity.
Every tissue is made up of 3 elements:
-cells
-intercellular products
-interstitial fluid
What is the study of tissue called?
Histology
What are the 4 main types of tissues in the body?
-muscle
-nervous
-epithelial
-connective
(Mum never eats cake)
Epithelial tissue
Covers all internal and external surfaces of the body.
Functions = protection, secretion, absorption
2 main divisions = covering/lining and glandular
Epithelium is classified according to how many layers of cells it contains and the sub-divided again depending on the types of cells it contains
Define simple epithelium
Epithelium is 1 cell thick
Define stratified or compound epithelium
Epithelium with 2 or more layers of cells.
Define simple squamous
-single sheet of thin, flattened cells on a basement membrane
-very thin and delicate
-found in areas where diffusion occurs
Define simple cuboidal
-one layer of cube shaped cells
-found lining many glands and ducts (kidney tubules, respiratory bronchioles)
-often has a secretory or absorption role
Define simple columnar
-tall and rectangular cells
-found lining many tissues with absorptive functions and secretory functions.
(Lines the intestines - aids in absorption of soluble food material).
Define ciliated
-more specialised, normally columnar epithelium
-free surface of cells have tiny hair like projections
-cilia on surface of each cell, increasing their surface area
-lines tubes and cavities where materials must be moved (respiratory tract and oviducts)
Define stratified (compound) epithelium
Dependant of the type of cells within the epithelium’s top layer, this can be stratified squamous, cuboidal or transitional.
-series of layers make it very tough (protective)
-found in areas subject to friction and wear (oesophagus, mouth, rectum)
-in abrasive areas, it’s strengthened further by infiltration with protein and keratin (keratinised) found on thr pads and skin
Define pseudostratified epithelium
Gives multiple layered appearance, but only single
Nuclei irregularly placed
Define transitional epithelium
-specialised stratified epithelium (many layers)
-found in structures that stretch and distend (bladder and ureters)
-appearance of cells will change according to distension of the structure
Define glandular epithelium
-columnar epithelium containing goblet cells
-goblet cells secrete materials into the cavity or space they are lining
-folding of glandular epithelium results in formation of a gland
-secretions from glands include enzymes, mucus, milk, sweat, tears, wax and saliva
Define endocrine glands
Secretions enter extracellular fluid and then diffuse directly into the bloodstream without flowing through a duct. These secretions are called hormones and regulate many metabolic and physiological activities to maintain homeostasis.
Develop from epithelium tissue, but separated from epithelium surface
Define exocrine glands
Secretions flow onto the free surface of the epithelium, usually via tube-like ducts.
(Sweat and salivary glands)
‘Pockets’ in epithelial tissue
Ducts connecting onto the surface
Variety of shapes
Define adenoma
Benign tumor
Formed from the glandular structures.
Type of exocrine gland
-sweat/sudorific gland
-mribomian (eye) gland
- 4 salivary glands
-anal gland
-mammary gland
-gastric/fundic (stomach)
-Brunners (duodenum)
-sebaceous
Type of exocrine gland
-pituitary
-thyroid
-adrenal medulla
-adrenal cortex
-islets of Langerhans (pancreas)
-ovaries
-parathyroid
-testes
Define connective tissue
Responsible for supporting and binding together all the organs and tissues of the body. It forms the transport system carrying nutrients around the body and removing waste.
Connective tissue consists of a ground substance or matrix, with cells and fibres embedded within the matrix.
What are the 2 types of fibres in connective tissue?
Collagen = gives strength to tissues (secreted by fibroblasts)
Elastic = allows stretching
Define loose connective tissue
Most common type of connective tissue
Define areolar connective tissue
Found all over the body
Lots of cells arranged in a loose irregular network of fibres
Contains - loose network of 2 types of protein fibres (collagen and elastic) , some adipose cells, varying numbers of macrophages.
Forms subcutaneous tissue of the skin and is located between organs
Protective function
Define adipose tissue
Similar structure to areolar but contains a greater number of fat cells
Functions: energy source, insulator against heat loss, protective role around the kidney and eye, food reserve
Define dense connective tissue
2 types = regular or irregular
The name refers to the arrangement of the collagen and elastic fibres within the tissue
Parallel - regular
Irregularly interwoven - irregular
This tissue contains large number of fibres in proportion to the number of cells within the matrix.
Define regular fibrous/dense connective tissue
Collagen fibres are parallel
Forming strong bands of fibrous tissue (tendons and ligaments)
Tendons connect - muscle to bone
Ligaments connect - bone to bone
Irregular fibrous/dense connective tissue
Forms sheets of connective tissue
Fascia and aponeuroses
Fibres are irregularly arranged - making the tissue impact resistant, bearing stress in all directions
Define cartilage
A specialised connective tissue
Rigid, yet flexible and able to bear weight.
It’s avascular, no blood supply.
Nutrition is supplied by perichondrium (fibrous connective tissue covering the cartilage)
Consists of:
-gel like ground substances
- fibres
-chondrocyte cells
Name the 3 types of cartilage
Hyaline
Elastic
Fibrocartilage
Define hyaline cartilage
-simplest and commonest form of cartilage
-chondrocytes within a hyaline matrix fine with collagen fibres, randomly arranged
-appears bluish-white and translucent
Found on articular surfaces or joints
-smooth surface for joint movement
-absorbing some of the forces placed on the joint
-also found on nose, larynx, trachea, bronchi and embryo skeleton
Function - covers the bone ends and provides a smooth surface to prevent friction.
Define elastic cartilage
Similar to hyaline, but as well as collagen fibres they also contain a large number of elastic fibres
Fibres run through the matrix at all directions
Function - support and flexibility
Found - external ear and epiglottis
Define fibrocartilage
Strongest form of cartilage
Higher number of collagen fibres in place of hyaline
Function - to give strength and tough support
Found - intervertebral discs, menisci of the stifle, attaches the tendons and ligaments to bone
Define bone
Ground substance containing collagen fibres and a protein (osteonectin) osteoid
Surrounded by fibrous membrane - periosteum
Calcium phosphate is deposited into osteoid
Bone hard and rigid - compact bone
Blood vessels and nerves run through the bone matrix - cancellous/spongy bone
Define haematopoietic tissue
Specialised connective tissue forming bone marrow in long bones
Jelly like consistency
Role - formation of blood cells
Define blood
Highly specialised connective tissue that circulates through the blood vessels
Role - supply oxygen and nutrients, remove waste to other organs for excretion
Consists of a number of different cells, fluid ‘ground substance’ , plasma
Name the 3 different types of muscle
-cardiac
-skeletal
-smooth
Define skeletal muscle
Voluntary movement
Provides movement of the skeleton
Consists of muscle cells - long and cylindrical in parallel
Fibres are grouped together in bundles - held by connective tissue
Whole muscle is enclosed by a connective tissue muscle sheath. Continuous with the tendons connecting it to the bone
Define smooth muscle
Involuntary movement
‘Visceral’ muscle , found in internal organs walls
Long, spindle shaped cells
Surrounded by connective tissue forming sheets
Nuclei in the centre of the cell - unlike striated muscle
No ‘stripes’ hence smooth muscle
Define cardiac muscle
Involuntary
Makes up the myocardium
Responsible for heart contractions - under the control of the autonomic nervous system
Cells are cylindrical as striated muscle
Fibres branch creating a ‘network’ - linked by intercalated discs
Centrally placed by nucleus
Define nervous tissue
Main cell within the nervous tissue is a neuron
- transmits nerve impulses from one area to another
Multiple neurons and synapses make up nerve pathways
-neuromuscular junction: muscle fibre
Define exoskeleton
An outside skeleton, arthropods (spiders, crustaceans, insects and crabs).
Define endoskeleton
An inside skeleton, vertebrates
What does the structure of bone consist of.
- Osteocytes sitting in lacunae in the matrix
- Cell types
- Matrix comprised of abundant mineral salts and collagen fibres
Define osteoblasts
Forms bone tissue
Define osteocytes
Maintains bone tissue
Define osteoclasts
Functions in resorption.
The destruction of bone matrix
Compact bone
-in the cortex
-outer compact bone = very hard, formed by concentric layers (lamellae) that surround small holes (Haversian systems).
-A Haversian canal surrounded by concentric lamellae forms a unit called osteon.
-osteons = packed together to form compact bone
- 1 osteon = Haversian system
Cancellous bone
AKA - spongy bone
-located beneath compact bone
-consists of meshwork of bony bars (trabeculae) with many interconnecting spaces containing bone marrow.
Medulla
-mainly contains yellow marrow in adults, red marrow in young.
-periosteum = membrane covering bone except where articular cartilage is present.
-innervation and blood supply
-long bones = via nutrient epiphyseal and periosteal artery and vein
-rich nerve supply accompanies blood vessels and are present in periosteum.
What is epiphysis ?
End of a long bone where bone growth takes place
What is diaphysis?
Shaft of a long bone
Function = to transport oxygen and immune support, mineral and fat storage
What is metaphysis ?
Part of a long bone
Contains growth plate of the epiphysis
Bone formation: endochondral ossification
-bone develops first as hyaline cartilage in the embryo, then becomes ossified
1. A hyaline cartilage model is made in the embryo
2. Primary centres of ossification appear in the centre of the diaphysis of the bone
3. Osteoblasts are laying down bone to replace the cartilage
4. Gradually extends towards the ends of the bone
5. Secondary centres of ossification appear in the epiphysis
6. Osteoblasts are also laying down new bone
7. Primary and secondary centres of ossification eventually meet at a band of cartilage called the epiphyseal growth plate.
8.the epiphyseal growth plate produces new cartilage on the epiphyseal side, thus steadily elongating the bone.
9. The cartilage cells on the diaphysis side are converted to bone by osteoblasts
10. Still happening
11. Osteoclasts start to remove some of the new bone tissue from the centre of the diaphysis to form the marrow cavity
12. Once the bone reaches its full length, the cartilage cells in the growth plate stop dividing
13. No further growth is possible
Bone formation : intramembranous ossification
-osteoblasts lay down bone between 2 layers of fibrous connective tissue
-there is no cartilage template (eg-skull)
Parathyroid hormone role in bone homeostasis
-increases activity of osteoclasts, calcium is released into the blood stream from the breakdown of bone. Inhibits osteoblasts.
-increases rate phosphate is excreted by the kidney, causing release of calcium and phosphate from the bone
Vit D/calcitriol (precursor) role in bone homeostasis
-increases calcium levels in blood through reabsorption in the gut and kidney
-promotes osteoclast activity
Calcitonin (thyroid c cells)
-has the opposite effect
-decreases the activity of osteoclasts and so blood levels of calcium fall
-increases activity of osteoblasts so more calcium is stored.
Fracture repair
- Inflammatory phase = with haematoma formation
- Repair phase = a fibrocartilage callus is formed and trabecular bone is laid down
- Remodelling phase = the trabecular bone is replaced with compact bone
Healing bones
Direct healing = bone edges close enough to not require the formation of a callus, often requires surgical stabilisation
Indirect healing = a callus forms, initially the response is similar to other tissues (haemorrhage, clot formation and acute inflammation)
Name the bone types
-long
-short
-flat
-irregular
-sesamoid
-pneumatic and splanchnic
Long bones
-connected with large movement
-have a diaphysis and 2 epiphyses
-epiphysis = the two ends of the bone
-metaphysis = the region where the diaphysis meets the epiphysis.
-outer layer of compact bone
-inner medulla contains marrow
Short bones
-almost cube shaped
-associated with smaller, complex movements
-outer layer of compact bone
-core of cancellous bone
-no medullary cavity
-develop from 1 ossification centre
-carpal and tarsus bones
Flat bones
-protect internal organs
-flat in shape
-compact bone outer cortex
-cancellous bone inside
-no medullary cavity
-stretch out in 2 directions as they grow
-skull bones, scapular and ribs
Irregular bones
Structure is similar to short bones, but they are irregular in shape
-vertebrae
Sesamoid bones
-sesame shape
-lie in tendons or occasionally ligaments over bony prominences
-changing the course of the tendon, reducing wear
-patella
Pneumatic bone
-contain air filled spaces within medullary cavity
-reduces the weight
-frontal sinus and avian skeleton
Splanchnic bone
-develop within soft tissue
-unattached from the rest of the skeleton
-os penis
Functions of the skeleton
-support
-protection
-leverage
-attachment of skeletal muscle
-storage
Functions of the skull
-houses and protects the brain
-houses and protects special senses (sight, smell, taste etc)
-houses dentition
-allows air and food entry
-attaches to hyoid apparatus
-attaches to masticatory and expression muscles
-communication
(Most skull bones are joined together by fibrous joints).
Nasal chambers
Nasal septum (cartilaginous plate dividing the nasal chambers lengthways, delicate ‘scrolls’ of bone)
Ethmoid bone (caudal boundary of the nasal chamber, separating it from the cranium)
Cribriform plate (sieve like area with numerous foramina, olfactory never pass nasal mucosa to brain)
Ventral nasal chambers - made up of the hard palate (incisive bone, part of the maxilla bone, palatine bone)
Condylar process
-temporomandibular joint
-coronoid process
-masseteric fossa
Hyoid apparatus
-lies in the intermandibular space
-made up of a number of small bones
-suspends tongue and larynx from base of skull
-articulates with the temporal region (cartilaginous joint)
-moves backwards and forwards (moving the larynx)
Skull shapes
Varies between species
More rounded in the cat, diff shapes for dogs (brachycephalic, dolichocephalic, mesocephalic/mesaticephalic)
Vertebrae
Cervical = neck
Thoracic = ‘chest’
Lumbar = lower back and abdomen
Sacral = pelvic area
Caudal/coccygeal = tail
Vertebral formula of cat and dog = C7, T13, L7, S3, C20-23
Functions of the vertebral column
-stiffen body axis
-protect spinal cord
-protects soft tissue ventral to spine
-insertion of muscles for movement
Basic vertebrae structure
-roughly cylindrical ventral body
-Cranially convex
-Caudally concave
-neural arch = neural or vertebral foramen (containing the spinal cord and link forming vertebral canal)
-the neural arch has a dorsal projection (spinous process), also lateral (transverse process)
-cranial and caudal edges of the neural arch (cranial and caudal articular process)
-various other processes- muscle attachment
Intervertebral discs
-tough fibrocartilage connective tissue
-‘shock absorber’
-connective tissue outer area (annulus fibrosus)
-gelatinous core (nucleus pulposus)
-ligaments join adjacent vertebrae
Cervical vertebrae
Atlas (C1) = no body or spinous process, 2 ‘winged’ lateral masses, articulates with occcipital condyles of the skull
Axis (C2) = elongated spinous process, nuchal ligament, Cranially is the dens/odontoid process
Thoracic vertebrae
Distinctive tall spinous process
Articular with the ribs via:
-costal fovea, forms synovial joint with head of rib
-transverse fovea, forms synovial joint with tubercle of rib
Lumbar vertebrae
Large bodies
Long transverse process extending cranioventrally
Lumbar muscles attach to the transverse processes
Sacral vertebrae
Sacrum
Spinal cord starts to gradually taper in this region
The sacrum forms a fibrosynovial joint between the sacrum and the wing of the ilium.
Sacroiliac joint
Coccygeal vertebrae
Vertebrae that vary in shape and number
Ribs and sternum
Ribs:
Flat bone
Dorsally bone
Ventrally costal cartilage
-ribs 1-8 eternal ribs
-ribs 9-12 asternal or false ribs
-ribs 13 floating rib
Sternum:
8 sternebrae
Manubrium most cranial bone
Sternebrae 2-7 (short cylindrical bone)
8th sternebrae is longer and dorsoventrally flatted (xiphoid process)
What is the appendicular skeleton composed of?
-pectoral or forelimb
-pelvic or hindlimb
-shoulder and pelvic girdles
Clavicle
(Forelimb)
Clavicle = collarbone (frequently absent in dogs)
-cartilaginous in dogs (vestigial)
-ossified in cats
Scapular or shoulder blade
(Forelimb)
-prominent spine on the lateral surface (supraspinous fossa, Infraspinous fossa)
-distal end of the spine (acromion)
-the scapula narrows distally (neck)
-shallow articular socket (glenoid cavity, articulates with the humerus)
Humerus
(Forelimb)
-proximally large, rounded head (greater tubercle laterally, lesser tubercle medially)
-slightly twisted shaft
-distally it forms the elbow joint (medial epicondyles, lateral epicondyles, olecranon fossa and supratrochlear fossa which is only in dogs)
Radius and Ulna
(Forelimb)
Ulna:
-olecranon = point of elbow
-trochlea notch
-anconeal process
-lateral styloid process
Radius:
-rod shaped bone, shorter than the ulna
-medial styloid process
-fovea capitis - articulation with the humerus
Carpus
(Forelimb)
7 short bones, arranged in 2 rows
Proximal row: radial carpal bone, ulna carpal bone, accessory carpal bone
Distal row: articulates with the 4 metacarpal bones
Metacarpus
(Forelimb)
Dog and cats 1st metacarpal bone is smaller and non weight bearing (dew claw)
Metacarpal II-V articulate proximally with carpal bones and distally with phalanges
Digits or phalanges
(Forelimb)
Proximal phalanx (articulates with metacarpus)
Middle and distal phalanx distally forms ungual process
Small sesamoid bones = metacarpophalangeal joints and distal phalangeal joints
Pelvis
(Hindlimb)
2 hip bones - join and pubic symphysis
Each hip bone us made up of 3 bones = ilium, ischium, pubis
Its a sacroiliac joint
Acetabulum
Teres or round ligament
Obturator foramen (to reduce density, a channel for nerves and arteries, attachment for muscles/ligaments)
Femur
(Hindlimb)
-head of femur
-neck
-greater trochanter
-medial and lateral condyle
-trochlea groove
Tibia and fibula
(Hindlimb)
-Tibia expands proximally forming dorsal prominence (tibial crest, quadriceps femoris attaches)
-The distal tibia = medial malleolus
-fibula is a thinner bone lying laterally = lateral malleolus
Tarsus
(Hindlimb)
7 short tarsal bones (arranged into 3 rows)
-talus and calcaneus
-talus articulates with the tibia
-Calcaneus articulates with the fibula (tuber calcis)
Metatarsus
(Hindlimb)
Anatomy similar to metacarpus and digits of the forelimb
Some animals have a small metatarsus I (hind dew claw)
Splanchnic Skeleton
(Hindlimb)
Develops within soft tissue
Not attached to the rest of the skeleton
(Os penis)
(Urethra runs within the urethral groove on the ventral surface of the bone in dogs)
Define tendon
Connects muscle to the bone
Define tendon
Connect one bone to another bone
Define ligaments
Connects one bone to another bone
Structure of skeletal muscle
-Muscle is made up of individual muscle cells or fibres (myofibre)
-connective tissue surrounds the myofibres (endomysium)
-myofibres are grouped in bundles or fascicles (perimysium)
-connective tissue surrounds the groups of fascicles that make up the muscle (epimysium)
Myofibres
The cell membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm system of channels called the sarcoplasmic reticulum.
Structure of muscle fibre
Each myofibre is made up of myofibrils and each myofibril contains the sarcomere (the unit of contraction), contractile proteins (actin - thin filaments, myosin - thick filaments)
It is these 2 fibres that give the microscopic ‘striped’ appearance (striated muscle).
Slow skeletal muscles (type 1)
‘Slow twtich’
Have more mitochondria, capillaries (red) and myoglobin than their fast-twitch counterparts.
They can burn oxygen very efficiently aerobic, and are very useful for running or cycling for long distances.
Fast skeletal muscles (type 2)
‘Fast twitch;
Burn fuel anaerobically, eg without the use of oxygen in the process. These muscle fibres come in handy when generating speed in short bursts. Fast twitch muscle fibres are useful for running or cycling shorter distances at greater speed.
(Rich in capillaries - red)
Muscle contraction
A nervous impulse arrives at the neuromuscular junction which causes a release of a chemical called acetylcholine (Ach). Depolarisation of the motor end plate causes calcium (Ca+) to be released. In the presence of high Ca+ concentrations, myosin filaments can now attach to the actin, forming a cross-bridge
The breakdown of ATP releases energy which enables the myosin to pull the actin filaments inwards and so shortening the muscle. This repeated pulling of the actin over the myosin is often known as the rachet mechanism.
muscular contraction can last for as long as there is adequate ATP and Ca+ stores.
Once the impulse stops the Ca+ is pumped back and the actin returns to its resting position causing the muscle to lengthen and relax.
A single nerve fibre innervates a number of muscle fibres via a number of muscle fibres via a neuronal impulse (motor unit).
For accurate and delicate movements motor unit contains few muscle fibres.
For movement requiring less accuracy motor unit will be larger.
Define isometric muscle contraction
Tone
The muscle does not shorten
Tone is maintained by a number of motor units contracting whilst others relax within a muscle belly.
The degree of tone in a muscle is controlled by the nervous system.
Increases when anxious/frightened
Reduces when relaxed and asleep.
It also allows the animal to maintain posture, muscles in a state of tension
Define isotonic muscle contraction
Muscle fibres all contact shortening the muscle.
This allows the actin and myosin filaments to move over each other, increasing the degree of overlap.
This is achieved by ‘bridges’ forming between the 2 filaments which are then ‘pulled’ shortening the sarcomere.
-ratchet mechanism shortening the muscle
-the cross bridges then reform and pull again, this process requires energy (ATP).
-relaxation, the cross bonds allow the myosin to move back
Define origin
(Muscles)
The starting point.
The muscle is attached to bone at 2 points. Moves least during contraction.
Proximal or medial tendon
Define insertion
(Muscle)
Opposite end to the origin. Where muscle inserts on the bone.
Define belly
(Muscle)
‘Classically’ shaped muscle.
Thick, fleshy central part
Define head
(Muscle)
Tapers at each end of the belly
Connective tissue muscle sheath is continuous with the dense fibrous connective tissue of the tendon that attaches the muscle to a bone.
Antagonistic pairing
(Muscle)
2 muscles that counteract each other
(Eg biceps, flexing and extending)
Aponeurosis
When muscles are presented in flat sheets the tendon is also drawn out into a flat sheet of connective tissue
(Eg the abdominal muscle)
Define sphincter muscle
Some muscles form a circular ring, controlling entry or exit to a structure
Extrinsic muscles
Muscles originating on the axial skeletal
Inserting on appendicular skeleton
Produce movement of whole limb
Intrinsic muscles
Originate and insert on one structure (such as the limb)
Cause movement within the limb
What is a bursa?
Protective layer under the tendon.
It’s filled with synovial fluid over the point of the bone to reduce friction.
Connective tissue of a bursa may surround the tendon, allowing smooth movement over the the bone (synovial or tendon sheath)
Masseter
(Muscles of mastication)
From dorsal skull
Inserts onto lateral mandible
Closes the jaw
Temporalis
(Muscles of mastication)
Over masseteric fossa on lateral mandible from zygomatic arch
Closes the jaw
Digastricus
(Muscles of mastication)
From caudovental mandible to jugular processes
Opens jaw with gravity
Moves jaw from side to side
Vertebral column
(Muscles of the trunk)
Expaxial muscles = dorsal to transverse processes of vertebrae
Hypaxial muscles = ventral to transverse processes of vertebrae
External and internal intercostals
(Thoracic muscles)
External = most superficial muscle, run caudo-ventrally, inspiration
Internal = next layer down to external, run cranio-ventrally, expiration
Diaphragm
(Thoracic muscles)
Attaches to sternum, caudal rib and lumbar vertebrae.
Central tendinous area
Main muscle of inspiration
Innervated by phrenic nerve
Division of thoracic and abdominal cavities
External abdominal oblique
(Abdominal wall muscles)
Broad, flat muscular sheets
provides abdominal wall strength = protection and support.
Most superficial
Runs in various directions
Originates; lateral surface of ribs and lumbar fascia.
Inserts; midline aponeurosis, linea alba.
Internal abdominal oblique
(Abdominal wall muscles)
Inserts on the linea alba
Transverse abdominis
Inserts onto the linea alba
Rectus abdominus
(Abdominal wall muscles)
Originates - 1st rib and sternum
Inserts - pubis, pre-pubic tendon
Linea alba
(Abdominal wall muscles)
Aponeurosis of the 3 lateral abdominal muscles
Runs from the xiphoid process to the pubic symphysis
Inguinal ring
(Abdominal wall muscles)
Aponeurosis of abdominal muscle at groin
Spermatic cord, vessels and nerves to the external genitalia
Trapezius
(Muscles of the forelimb)
Origin - mid cervical and thoracic vertebrae
Insertion - spine of scapula
Action - abductor of the forelimb and pulls the leg forwards (protraction)
Pectorals
(Muscles of the forelimb)
Origin - ribs and sternum
Insertion - humerus
Action - adducts the limb, keeping it close to the body wall
Latissumus dorsi
(Muscles of the forelimb)
Origin - thoracic vertebrae
Insertion - humerus
Action - flexes the shoulder and retracts the limb
Brachiocephalicus
(Muscles of the forelimb)
Origin - based of skull
Insertion - cranial humerus
Action - limb on ground = bends the neck laterally. foot off ground = pulls leg forwards (protraction)
Supraspinatus and infraspinatus
(Intrinsic muscles - attach and insert on forelimb)
Supraspinatus
origin = Supraspinatus fossa
Insertion = greater tubercle of humerus
Action = stabilises and extends the shoulder
Infraspinatus
Origin = infraspinatus fossa
Insertion = greater tubercle of humerus
Action = stabilises and flexes the shoulder
Both are known as an antagonistic pair.
Intrinsic muscles of the elbow
Triceps brachii
Origins = 3 heads from the proximal humerus, 4th from the scapula
Insertion = olecranon of ulna (a bursa is also present)
Action - extends the elbow
Biceps brachii
Origin = supraglenoid tubercle of the scapula
Insertion = radius and ulna
Action = flexes the elbow
(Biceps tendon crosses shoulder joint)
Brachialis
Origin = humerus
Insertion = radius
Action = flexes the elbow
Intrinsic muscles of carpus and digits
Carpal extensors
Origin = humerus
Insertion = carpus
(Cranial and lateral aspect of the limb)
Digital extensors
Origin = humerus
Insertion = 3rd phalanx
(Cranial aspect)
Carpal flexors
Run palmar to carpus
Digital flexors
Superficial digital flexor (inserts on 2nd phalanx)
Deep digital flexor (inserts on the 3rd phalanx)
Sub-lumbar hypaxial muscle
(Muscles of hindlimb)
Extrinsic
Ventral to vertebral column attaching to axial skeleton by the pelvis
Less extrinsic muscles compared to the forelimb
Intrinsic muscles of thigh
(Muscles of hindlimb)
Group have common origin and insertion
Origin = pelvic girdle
Insertion = femur
Gluteals (superficial, middle and deep)
(Muscles of the hindlimb)
Create ‘curve’ of rump
Action = extensors of hip
Hamstring group
(Muscles of hindlimb)
Bicep femoris
Origin = pelvis
Insertion = calcaneus
Action = extends hip, flexes stifle and extends hock
Semitendinous
Origin = pelvis
Insertion = tibia and calcaneus
Action = extends hip, flexes stifle and extends hock
Semimembranous
Origin = pelvis
Insertion = femur and tibia
Action = extends hip and flexes stifle
Quadriceps femoris
(Muscles of the hindlimb)
Largest muscle running down the cranial aspect of the thigh
4 parts to the muscle; 3 originating from the proximal femur, 1 originating from the ilium
Insertion = tibial tuberosity
(Tendon of insertion contains the patella)
Action = stifle extension
Adductor muscles
(Muscles of the hindlimb)
Pectineus
Origin = pubis
Insertion = distal femur
Sartorius
Origin = pelvis
Insertion = cranial tibia
Gracillis
Makes up caudal medial thigh
Intrinsic muscles of lower hindlimb
Gastrocnemius
Origin = caudal femur
Insertion = calcaneus
2 small sesamoid bones in tendon caudal to stifle
Action = extends hock, flexes stifle
Achilles tendon
Large, strong tendon running down caudal aspect of leg to point of hock.
Contains 3 tendons of insertion onto calcaneus
One tendon passes over hock - (Superficial digital flexor)
Intrinsic muscles of hock and digits
Anterior tibialis
Origin = proximal tibia
Insertion = tarsus
Action = flexes hock and rotates paw medially
Digital extensors
Run down cranial aspect of limb
Digital flexors
Run down plantar aspect of limb
Superficial digital flexor attaches onto 2nd phalanx
Deep digital flexor attaches onto 3rd phalanx
What are the 3 types of joints?
Fibrous
Cartilaginous
Synovial
Fibrous joints
Joints occur where bones are held rigidly together by fibrous tissue.
Fibrous joints also classed as - synarthroses (a joint that permits little or no movement)
Examples of fibrous joints
Fibrous joints join the flat bones of the skull (sutures)
Syndesmoses (fastened with a band) between 2 areas of bone - radius and ulna
Gomphosis joints - the specialised fibrous joint that anchors the root of a tooth into its bony socket within the maxillary bone (upper jaw) or mandible bone (lower jaw)
Cartilaginous joint
The bones are connected by either fibrocartilage or hyaline cartilage and there is no space between the bones. They allow limited or no movement (amphiarthroses)
2 main types of cartilaginous joints
Synchondroses - bones are connected by hyaline cartilage. They are immovable (synarthrosis)
Eg - the joint between the diaphysis and epiphysis of a growing long bone in a growing animal.
Symphases - where the bones are united by a layer of fibrocartilage. They are slightly moveable (amphiarthrosis)
Eg - include the joints between vertebral bodies and the pubic mandibular symphysis
Synovial joints
Aka diarthroses
Allow a wide range of movement
Joint surfaces (articular surfaces) covered in hyaline cartilage.
Bones are separated by a space filled with synovial fluid (aka joint cavity). The whole joint is surrounded by the joint capsule.
It has an outer fibrous layer (protection)
An inner layer known as the synovial membrane which secretes synovial fluid.
Define articular cartilage
Protects the 2 bones
Define synovial membrane
Producers synovial fluid
Define joint capsule
Holds the joint together in a tough membrane
Name the stabilising ligaments found around/within synovial joints
Collateral Ligaments
Cruciate ligaments
What is menisci
Found within synovial joints.
Intra-articular discs of fibrocartilage act as shock absorbers within joint
Eg- stifle joint and jaw
Synovial fluid
-viscous, straw coloured fluid
-varies in consistency (fitness and disease)
-lubricates joint surfaces
-provides nutrients for articular cartilage
Define flexion and extension
Flexion - decreases angle between bones
Extension - increases angle between bones
Define abduction and abduction
Abduction - moves limb away from body
Adduction - moves limb towards midline of the body
Define Circumduction
The limb moves in a circle
Define rotation
The limb turns round on its long axis, like using a screw driver
Define gliding/sliding
When one articular surface slides over another
Define Pronation and supination
Pronation - Turing the lower surface of the paw downwards
Supination - rotation of the paw upwards
Define protraction and retraction
Protraction - moving the lib cranially, meaning it advances the limb forward (walking)
Retraction - moving the limb back towards the body
What is scapular retraction and protraction ?
Retraction - moving the shoulder blades (scapula) towards the spine
Protraction - moving the shoulder blades away from the spine
Define hinge
Enable movement
similar to the opening and closing of a hinged door, but only in one plane (Flexion and extension)
(Elbow)
Define condylar
Where a convex surface fits onto a concave surface allowing Flexion and extension then over-extension
Allows movement in 2 planes; Flexion, extension and then over-extension (eg carpal joint, stifle)
Define pivot
This is where a bone sits inside another bone and allows rotation
Eg - atlantoaxial Joint
Define ball and socket (spheroidal)
Consist of the ball head of one bone fitting into the socket of an adjacent bone - most freely moveable joint.
Allows Flexion, extension, abduction, adduction, rotation and Circumduction
(Eg hip and shoulder)
