Support and movement

what are the 2 categories that lead to developmental defects

genetic mutations

teratogens

teratogenic

agents that lead to genetic defects in an embryo

how do we stop developmental defects

stop breeding the animals with the mutant gene

eliminate the teratogen

what factors affect the severity of developmental defects

dose of the teratogen
the amount of time the embryo is exposed to the teratogen

what are common factors of reproductive failure

chromosomal abnormalities

teratogenic factors

poor conditions (nutrition and stress)

idiopathic

co-dominant traits

both genes are expressed (blood types)

haploinsufficiency

when only 1 allele is able to be expressed and the other is null leading to the dominant gene only being partially expressed

single gene mutations

when a mutation occurs on a single gene (albinism, dwarfism, myotania congeita)

Malignant hypothermia in pigs

autosomal dominant mutation of RYR1
affects calcium channel in muscles
point mutated gene is dominant over wild type allele causing production of bad protein

how are we able to observe chromosomal abnormalities

using a microscope

aneuploidy

having an abnormal amount of chromosomes

monosomt

lose of a chromosome (X0)

trisomy

having an extra chromosome (XXY)

how does selective breeding lead to genetic consequences

over selecting for 1 gene can cause deleterious affects on other genes (incel chicken)

teratogen agent categories

environmental pollutants

mycotoxins

latrogens (injury from medical treatment)

ionizing radiation

infection

bacteria

protozoa

metabolic imbalance

iatrogenesis

harm caused by medical treatment

what are the six principles of teratology

severity depends on the genotype

depends on when the embryo is affected

how the teratogen gets to the embryo

teratogens act in specific ways

manifestations of development (death, malformation, growth retardation, functional defecct)

low levels of teratogen = low effect

what stage of development have low sensitivity to teratogens

fertilization and zygote

what stage of development has high sensitivity to teratogens

blastocyst, embryo, and fetus

palate, urigeneital, repro system and cerebellum remain developing into late gestation

what are the 5 components of the musculoskeletal system

Bone

Muscle

tendon

ligament

joints

what are the functions of bone

provide support and structure

protection of organs

movement

hematopoiesis

endocrine regulation (calcium)

sesamoid bone occur where

>90 degrees range of motion

significant force at the end of motion

Function of a sesamoid bone

protects the tendon and aid with muscle leverage

what are the 4 classifications of bones

long bones (femur and humerus) longer than they are wide

short bones (carpal and tarsal bone)

flat bones (skull and ilium)

irregular bones (vertebrae and mandible)

diaphysis

shaft of the long bone

metaphysis

neck of the bone

between diaphysis and epiphysis

physis

growth plate

cartilagenous

only seen while bone is growing (only juveniles)

epiphysis

region between physis and joint of the bone

apophysis

site of tendon or ligament attachment

non articular

large bony marking when mature

separate center of ossification

compact bone

solid inner part of the bone

found in the diaphysis of the bone

spongy bone

found in the metaphysis and epiphysis of the bone

medullary cavity

hollow space within the bone

site of hemtopoiesis

periosteum

outer surface of the bone

innervated (lots of sensation)

fibrous outer layer

inner osteogenic cell layer

endosteum

thin layer lining medullary cavity

helps to build and maintain bone

fossa

depression in bone

foramen

hole in bone

what are the 3 types of joints

fibrous

cartilaginous

synovial

ligament

connects bone to bone

made of collagen

strong but poor blood supply

what are the components and functions of synovial joints

synovial cavity with synovial fluid

joint capsule

synovial lining

hyaline cartilage

subchondral bone

high motion

fibrous joints

connective tissue junction

limited movement

suture joints

found in the skull

dense irrgeular connective tissue

syndesmoidal joints

ligamental sheet to connect long bones

gomphosis

ligamentous connection

connect bone to jaw

cartilaginous joints

connective tissue junction

limited junction

cartilage present

synchondrosis

bones connected by cartilage (ribs to sternum)

symphysis

bones connected by cartilage and connective tissue (vertebrae)

muscle

50% of body weight

composed of 2 types of fibers

large blood supple

innervation is specific to each muscle

where do muscles attach to bones

origins (less motion) and insertions (more motion)

tendon sheaths

column of fluid around the tendon

contain synovial lining and fluid

bursa

pocket of fluid between the tendon and bone

decreases friction on the tendon

contain synovial lining and fluid

plantargrade

the entire plantar is on the surface of the ground

digitigrade

only the digits are on the ground

unguligrade

hooved animals

only the 3rd phalanx is on the ground

proximal carpal bones

accessory carpal bone

named for adjacent long bones

ulnar carpal bone lateral

radial carpal bone medial

distal carpal bone

numbered from medial to lateral

clavicle

not found in dogs only cats

stabilizes thoracic limb allows for abduction

antebrachium in ruminant

complete ulna

partial fusion to the radius

carpus of ruminant

proximal carpal bones (radial, intermediate, ulnar accessory)

distal carpal bones (fused II and III) and IV (lateral)

metacarpals in ruminant

III and IV (III is medial IV is lateral)

II and V vestigial

equine carpus osteology

only 1 metacarpal bearing weight (metacarpal III)

II and IV act as splint bones

equine antebrachium

vestigial ulna

fused radius

thoracic sling

Trapiezius (superficial)

Rhomboid (deep)

serratus ventrails

pectoralis

passive stabilization

requires no muscular activity and is provided by bony anatomy

active stabilization

muscles actively contract to prevent movement

shoulder stablizers

supraspinatus (cranial to spine of scapula)

infraspinatus (caudal to spine of scapula)

subscapularis (medial aspect of the scapula)

Equine biceps brachii

contains bicipital bursa to lubricate the joint

olecranon

formed from apophysis

anconeal process

coranoid processes

styloid process

cranial elbow flexors

biceps

brachialis

caudal elbow flexors

triceps brachii (4 heads in dogs)

elbow rotations

pronator teres
supinator

Small animal carpal bones

Proximal intermedioradial, ulnar, and accessory

Distal I, II, III, IV

fetlock

metacarpophalangeal joint

pastern

proximal interphalangeal joint

Coffin

distal interphalangeal joint

Carpal and digital extenders

Extersor carpi radialis

Common digital extensor

Later digital extensor

ulnaris lateralis

Carpal and digital flexors

Flexor carpi radialis

flexor carpi ulnararis

superficial digital flexor tendon

deep digital flexor tendon

digital flexors and extenders in the horse

no muscle fibers in distal limb

accessory ligaments for superficial and deep digital flexors

Feline digit

digit III retracts

Fibers of ECM

collagenous or fibrilis

reticular

Elastic

Ground substance of ECP

contains GAG’s and PG

structural glycoproteins

why does collagen quarter stagger

in bone the first mineral accumulates in those spaces

chondrocyte

cell pertaining to cartilage

how are fibrils aligned in cartilage

crossed over each other

why is a type 2 collagen molecule made of

trimeric protein

positively charged

what is the backbone of ground substance made of

GAG’s (chondroitin sulfate or Keratan sulfate)

where do sugars attach in cartilage

The PG (very negatively charged) attach to the GAG’s

what is the downside of PG’s being negativly charged

PG’s try to maximize the distance between each other due to their charge

PG’s are hydrophilic meaning that thy bind lots of water leaving the matrix to be squishy

causes stain to be very purple

Type 2 collagen

positively charged

trimeric molecule

PG/PAG’s

negativly charged

chondroitin and keratan sulfated side chains

Hyaline cartilage

avascular

nutrient and gas exchange in ECM

releases water when compressed but can reabsorb when compression alleviated

mesenchymal cell

precursor of all connective tissue cells

chondroblasts

divide and secrete ECM

distance themselves from neighbors

chondrocytes

cell completely surround by ECM

Isogenic cells

group of daughter cells in close proximity to one another

apositional growth

differentiation of chondroprogenitor cells into chondroblasts

interstitial growth

division of per-existing chondricytes in cartilage matrix

hyaline cartilage

structural support, rapid growth withstanding compression

found in fetal skeleton and respiratory passage