Hindlimb Flashcards
what is integument?
skin
what are the main functions of integument?
thermoregulation, secretion, sensory input, pigmentation, vitamin D metaolism
what is thermoregulation?
the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different
what parts of the body are the core temperature?
brain, thorax and abdomen
what happens to temperature after a normal increase in metabolic rate?
increase in temp
Describe the negative feedback loop for temperature
change in temp/body heat production change in body temp change in thermosensors change in hypothalamic activity altered heat loss/production body temp returns to normal range
what is the sacrotuberous ligament called in horses?
broad ligament
what is the difference in the sacrotuberous ligament in dogs and cats?
absent in cats
what muscles arise from the sacrotuberous ligament?
bicep femoris, superficial gluteal, piriformis and tenuissimus
where does the biceps femoris insert?
by way of aponeurosis over the proximal stifle region onto the tibial tuberosity, further aponeurosis and small tendon also contribute to the calcanean tendon
what is the action of the biceps femoris?
flexion and extension of the stifle, extension of the hock
what is the innervation of the bicep femoris?
ischiatic nerve
where is the femoral triangle?
proximal medial thigh
what are the boundaries of the femoral triangle?
caudal edge of caudal belly or sartorius, cranial edge of pectineus, iliopsoas
what important structures lie within the femoral triangle?
VAN - vein, artery nerve
femoral region so femoral VAN
which of the femoral VAN lies most caudally?
femoral vein most caudal, femoral vein is most cranial
do the femoral VAN lie superficially or deep within the femoral triangle?
superficially
what muscle does the femoral nerve supply?
sartorius and quadriceps
what are the GAPE muscles?
gracillis, adductors, pectineus, external obturator muscles
what cutaneous area does the femoral nerve supply?
doesn’t directly supply any cutaneous area
supplied by the saphenous branch of the femoral nerve
what area of the skin does the femoral nerve supply?
caudal/plantar leg, crus and pes
what area of skin does the saphenous nerve supply?
medial leg, crus and pes
is there a saphenous artery/vein on the medial aspect of the crus?
yes
medial and lateral branches of both artery and vein
how many heads does the gastrocnemius have?
2 heads - one medial and one lateral
which bony structures might be associated with the heads of the gastrocnemius?
the fabellae - one medial and one lateral
where does the gastrocnemius insert?
by way of strong tendon onto the calcanean tuberosity
gastrocnemius tendon initially lies superficial to the tendon of the SDFT, but then runs lateral and eventually deep to it to insert on the calcanean tuberosity
what is the innervation of the gastrocnemius muscle?
tibial branch of the ischiatic nerve
what does the sympathetic branch of the autonomic nervous system do to aid physiological thermoregulation?
changes in the blood supply to the skin and contracts the erector pili muscle
what are the the physiological thermoregulation responses?
autonomic nervous system, evaporative heat loss (panting and sweating), thermogenesis (shivering and non-shivering)
what is the role of the sympathetic nervous system in thermoregulation?
stimulates contraction of vascular smooth muscle controlling resistance in small blood vessels, stimulates contraction of erector pili muscle adjusting the insulating properties of fur and plumage by increasing thickness of trapped layer of air
what is the result of high ambient temperatures on sympathetic activity and what is the body’s response?
decreased sympathetic activity
relaxation of resistance arterioles so blood directed to the dermis through subcutaneous adipose tissue, bypassing insulation
erector pili muscle relaxed so less trapped air
what is the result of low ambient temperatures on sympathetic activity and what is the body’s response?
increased sympathetic activity
contraction of resistance arterioles, reduced blood flow in dermis and subcutaneous fat layer provides insulation against heat loss from vasculature
erector pili contracts, stands hairs up and increases trapped air in fur, providing further insulation
what is the order of species in regards to their normal core temperatures from low to high?
horse, cow/ox, pig, sheep, cat, dog
HOPS cat dog
which of the domestic species sweat the most?
horses sweat lots, cattle and sheep sweat moderately, pigs, dogs and cats sweat minimally
what do pigs, dogs and cats rely on most for evaporative heat loss?
panting
how does panting work?
rapid and shallow breathing that doesn’t go all the way down to the lungs, natural frequency of oscillation so relatively little energy expended, most of the water is coming from the nasal turbinates
will a panting dog develop a respiratory alkalosis?
no - panting doesn’t affect ventilation as it is only in the nasal turbinates
where does most energy generation take place in the body?
60-70% in the heart, brain, liver and kidney
how much energy is converted to heat during voluntary exercise?
80%
what is the shivering method of thermogenesis?
primary involuntary means of increasing heat production
antagonistic muscles contract simultaneously
what is the non-shivering method of thermogenesis?
increases basal metabolic rate by increasing thyroid hormone levels and in brown fat (skeletal muscle)
when is brown fat important for an animal and how do brown fat levels change as the animal ages?
important for lambs- 40% of heat production
important for hibernating animals
thought to disappear in adults/as the animal changes- some evidence emerging to suggest otherwise
what does thyroid hormone do?
causes slow-developing prolonged increase in metabolism
what does an increase in the secretion of thyroid hormones do to metabolic rate?
increases
what happens if an animal reaches the lower critical temperature of the thermoneutral zone (TNZ)?
animal must start heat production to maintain body temperature
what happens in an animal reaches upper critical temperature of the thermo neutral zone (TNZ)?
cutaneous blood flow has reached its maximum and extra energy is required for losing heat
how does an adult animals LCT and TNZ compare to that of a neonate?
lower LCT and wider TNZ
what is the name of vitamin D3?
cholecalciferol
where is vitamin D3 synthesised?
in the skin
describe vitamin D synthesis
7-dehydrocholesterol (7-DHC) interacts with sun to make cholecalciferol
what inhibits vitamin D synthesis?
dense fur coat and heavy pigmentation
what are the three stages of hair growth?
anagen (growing phase), catagen (transition phase with regression of the lower part of the hair follicle) and telogen (resting phase)
what affects the hair growth cycle?
genetic, age, hormones
when do most animal shed their coat?
seasonally- with the photoperiod
which hormones influence shedding of the coat?
prolactin and melatonin
how does photoperiod influence hair loss?
photoperiod references the length of the day and night
melatonin is produces in the dark
longer nights = more melatonin production = more shedding
how does an decrease in thyroid hormone impact hair growth/loss?
decreased time spent in anagen so less hair growth
increased times spent in telogen so increased hair loss
what do sebaceous glands do?
secrete sebum oil
what is the function of sebum?
oils hairs
forms an oily film on the skin that
retards water loss, lubricates skin, inhibits growth of certain bacteria, helps spread sweat, territorial marker for some animals
how is sebum secreted onto the skin?
escapes during piloerection as contractions of the piloerector muscle squeeze the gland
how is water resistance of the skin improved?
sebaceous gland secretions (lipids)
insoluble keratin within keratinocytes
how are sebaceous glands regulated?
regulated by sex steroid hormones
more active after puberty
larger and more productive in the breeding season
do birds have sebaceous glands?
none within feathers
during preening birds spread secretions from a gland at the base of their tail
what is the sebaceous gland at the base of a birds tail called?
uropygial gland
where are specialised skin glands found? (3 examples)
anal sacs in dogs and cats
interdigital pouch of sheep
infraorbital pouch of sheep
tail glands of dog
why is melanin production important?
camouflage, mimicry, social communication, protection against harmful effects of solar radiation
what is the function of melanocytes?
synthesis and package vesicles of melanin, intact vesicles are transferred into keratinocytes
when the keratinocytes reach the surface of the skin melanin is shed
what are the two pigments of melanin?
eumelanin (black and brown) and pheomelanin (red and yellow)
what can affect pigment synthesis?
genetics, local factors of the skin, hormones
describe the synthesis of melanin
melanin synthesising hormone (MSH) outside the cell binds to a MSH receptor in the cell membrane, reactions inside the cell result in pigment production
what stimulates the production of melanin synthesising hormone (MSH)?
UV light disease states (cushings syndrome) other external signals (camouflage)
what are keratinocytes?
main cells in the epidermis, stem cells in the stratum basale
what are melanocytes?
dispersed between basal cells, produce pigment (melanin)
what are Langerhans cells?
monocytes-derived dendritic cells, immuno-surveillance cells, important in antigen presentation
what are Merkel cells?
mostly present in basal layer, sensory associated with nerve endings
what are the layers of the skin starting deep?
dermis basal lamina stratum basale stratum spinosum stratum granulosum stratum lucidum stratum corneum
MOST SUPERFICIAL
what is the stratum basale?
a single layer of cuboidal cells in contact with the basal lamina
stem cells that divide to form new keratinocytes to replace those lost at the surface
what is the stratum spinosum?
spinous/prickle cell layer
several layers of keratinocytes bound tightly together by desmosomes
what is the stratum granulosum?
few layers of cells, lots of keratinisation, abundant granules
what is the stratum lucidum?
outermost dead cells, loss of nuclei, translucent keratinised epidermal cells
what is the stratum corneum?
the outermost layer of epidermis
flattened cells
dead keratinised cells, continuously sloughed off
what are the two layers of the dermis?
papillary layer (superficial) and reticular layer (deep)
which bones make up the pelvis?
ilium, pubis, acetabulum, ischium
which part of the pelvis is best used for harvesting bone marrow?
wing of the ilium
How many bones are in the sacrum of the dog compared with the horse?
3 in dog, 5 in horse
what kind of joint is the sacro-iliac joint?
fibrous joint, fused
what supports the sacro-iliac joint?
ligaments from lumbar and sacral vertebrae
what is the iliopubic eminence?
where the ilium meets the pubis
where is the pecten?
the concavity at the cranial aspect of the pubis
what fills the pecten?
prepubic tendon
what is the function of the prepubic tendon?
provides attachment for the gracilis, pectineal and several abdominal muscles
what attaches to the ischiatic arch?
muscle attachment for reproductive organs
what does the sacrotuberous ligament originate and insert?
originates at sacrum
inserts at tuber ischium
what is the pelvis symphysis?
where the two halves of the pelvis meet in the middle
what kind of joint if the pelvis symphysis?
a cartilage joint
how is the obturator foramen bound?
by the pubis and ischium
what passes through the obturator foramen?
blood vessels and nerves - obturator nerve
internal obturator muscle of hip rotation and stabilisation
what does the acetabulum articulate with?
the femur to make the hip joint
what ligament is in the acetabular notch?
transverse ligament
what attaches to the acetabular fossa?
teres ligament
what are the main centres of ossification for the pelvis?
in each bone of the pelvis - ischium, ilium, pubis, acetabulum
where are the secondary centres of ossification in the pelvis?
dorsal iliac crests, tuber ischium and ischiatic arch
how can you tell the difference between the pelvis of a cat and a dog on an xray?
in a dog, the wings of the ilium and ischium diverge
in a cat, the wings are parallel
cat has a larger and more oval shaped obturator foramen, a smaller greater trochanter and a larger lesser trochanter
how is the head of the femur arranged?
the greater trochanter is lateral and the head is medial
where are trochanters, trochlea and condyles on the femur?
trochanters are proximal
trochlear are distal cranial and condyles are distal caudal
what do the condyles of the femur articulate with?
the tibia to make the stifle joint
what ligament attaches to the intercondylar fossa of the femur?
cruciate ligaments
where is the popliteal fossa found?
the hollow behind the knee
where are the centres of ossification in the femur?
head
greater trochanter
body
distal epiphysis
what shape is the patella?
pyramid shaped
where is the patella?
sits in the trochlear groove
cranial distal femur
what directions does the patella move?
proximal and distal
how does the patella interact with muscle?
embedded in quadriceps muscle tendon of insertion, continues as patellar ligament inserts onto tibial tuberosity
what are the sesamoid bones of the femur called and where do they sit?
fabella
embedded in the gastrocnemius muscle at the caudal distal femur
which of the fabella is not usually ossified and so not visible on a radiograph of a cat?
medial fabella
which nerves supply the hindlimb?
gluteal
obturator
femoral
sciatic - branches into the tibial and fibular/peroneal
what bones make up the hip joint?
head of the femur and the lunate surface of the acetabulum of the pelvis
what stabilises the hip joint?
teres ligament/round ligament and surrounding muscle mass
what are the extrinsic abductor muscles of the hindlimb?
where are they in regards to the hip?
where to they originate and insert?
what innervates them?
gluteal muscles- superficial, middle and deep
dorsal to the hip
originate- sacrum and pelvis on the gluteal surface
insert- greater trochanter
innervated by gluteal nerve
what are the extrinsic adductors of the hip?
where are they in regard to the hip?
what innervates them?
GAPE muscles- all originate at ventral surface of hip Gracilis - inserts tibia and calcaneus Adductor Pectineus - femur External obturator innervated by obturator nerve
what are the extrinsic limb protractors/hip flexors?
tensor fascia latae
iliopsoas muscle
sartorius
rectus femoris
where does the tensor fascia latae originate and insert, and what is its innervation?
originates ilium, inserts fascia latae
gluteal nerve
where does the iliopsoas originate and insert, and what is its innervation?
originates lumbar vertebrae and ilium, inserts lesser trochanter of femur
femoral nerve
where does the sartorius originate and insert, and what is its innervation? how many heads does this muscle have?
2 heads
originates ilium, inserts femur (short head) and tibial tuberosity (long head) via patellar ligament
femoral nerve
where does the rectus femoris originate and insert, and what is its innervation?
part of the quadriceps muscle
originates at ilium, inserts at tibial tuberosity via patellar ligament
femoral nerve
which muscles are extrinsic limb retractors/hip extensors?
biceps femoris
semitendinosus
semimembranosus
where does the biceps femoris originate and insert, and what is its innervation?
originates tuber ischium, inserts fascia latae and calcaneus
sciatic nerve
where does the semitendinosus originate and insert, and what is its innervation?
originates ischium, inserts tibia and calcaneus
sciatic nerve
where does the semimembranosus originate and insert, and what is its innervation?
originates ischium, inserts femur and tibia
sciatic nerve
which bone of the crural region is weight bearing?
tibia
is the fibula medial or lateral?
lateral
is there rotation in the crus region?
no
where are the centres of ossification in the tibia?
proximal end, tibial tuberosity, body and distal end
where are the centres of ossification in the fibula?
proximal end, body, distal end
what are the bones of the stifle joint?
femur and tibia (and patella)
what are the menisci and where are they?
C shaped cartilage that is wedges, sits bewteen the femur and tibia at the stifle joint, one medial and one lateral
what are the functions of the menisci?
stabilise stifle joint, cushioning, proprioception (contain nerve endings, painful if damaged)
what do the menisco-tibial ligaments (MTL) do?
hold menisci to tibia
what does the transverse ligament of the stifle joint do?
between the cranial aspects of the menisci to stabilise menisci
what does the menisco-femoral ligament (MFL) do?
holds femur to menisci
where do the collateral ligaments of the stifle joint originate and insert?
medial epicondyle of femur to tibia
lateral epicondyle of femur to fibula and tibia
how do the cruciate ligaments sit?
in a cross (one cranial and one caudal) from the intercondylar fossa to the medial aspect of the lateral condyle (cranial) and the intercondylar fossa (caudal)
what is the function of the cruciate ligaments?
maintain femur over the menisci and resist rotation
where does the patellar ligament insert?
on tibial tuberosity
where does the patellar move when the limb is extended?
proximally onto the femur
where does the patellar move when the limb is flexed?
distally onto the tibia
what muscles are the extensors of the stifle?
sartorius (2 heads)
what muscles are the extensors of the stifle?
sartorius (2 heads)
what muscles are the extensors of the stifle?
sartorius (2 heads)
what muscles are the extensors of the stifle?
sartorius (2 heads)
quadriceps
what muscles are the flexors of the stifle?
biceps femoris
semitendinosus
semimembranosus
gastrocnemius
in which species are all the tarsal bones present?
pig and dog
what are the centres of ossification for the tarsal region?
each tarsal has one in the centre, except the calcaneus which has two
what is the joint called between the tarsus and crus?
which bones are articulating at this joint?
tarso-crural joint
between the talus and the tibia and fibula
what is the joint called between the proximal and medial rows of the tarsals called?
proximal intertarsal joint
what is the joint called between the medial and distal rows of the tarsals called?
distal intertarsal joint
what is the joint called between the tarsus and metatarsals?
tarso-metatarsal joint
what is the joint support at the tarsus?
synovial joint with capsules
what supports the tarsal region?
collateral ligaments (long and short)
plantar ligament
fibrocartilagenous reinforcement of joint capsule
retinaculum
where is the long collateral ligament of the tarsal region?
laterally - fibula to 5th metatarsal
medially - tibia to 2nd metatarsal
where is the plantar ligament and how does it work?
between the calcaneus and the metatarsal bones
counteracts pull on the calcanean tuberosity by common calcanean tendon
what are the functions of the fibrocartilagenous
reinforcement of joint capsule?
Friction free surface for passage of tendons
Passive maintenance of joint
what muscles flex the hock?
cranial tibial muscle
peroneus longus, peroneus brevis and peroneus tertius
long digital extensor muscle
lateral digital extensor muscle
what is the origin and insertion of the cranial tibial muscle and what innervates it?
originates at lateral tibia, inserts metatarsal bones
innervated by fibular branch of sciatic nerve
what is the origin and insertion of the peroneus longus muscle and what innervates it?
originates lateral tibia and fibula, inserts plantar tarsus
innervated by fibular branch of sciatic nerve
what is the origin and insertion of the peroneus brevis muscle and what innervates it?
originates tibia and fibula, inserts 5th metatarsal bone
innervated by fibular branch of sciatic nerve
what is the origin and insertion of the long digital extensor muscle and what innervates it?
originates at extensor fossa of femur, inserts at all digits
fibular branch of sciatic nerve
what is the origin and insertion of the lateral digital extensor muscle and what innervates it?
originates lateral aspect of tibia, inserts -as fuses with lateral branches of long digital extensor- on a few digits only
what muscles extend the hock?
common calcanean tendon (common tendons of biceps femoris, semitendinosus, gracilis, gastrocnemius and SDF
superficial digital flexor muscle
deep digital flexor muscle
what is the origin and insertion of the superficial digital flexor muscle and what innervates it?
originates at lateral popliteal fossa on the femur (associated with gastrocnemius)
inserts at calcaneus as part of the common calcanean tendon and further branches to all digits
innervated by tibial branch of sciatic nerve
what is the origin and insertion of the deep digital flexor muscle and what innervates it?
originates at tibia
laterally- runs over calcaneus, part of the fibrous reinforcement of joint capsule, held by retinaculum, protected by tendon sheath
medially- runs over medial aspect of tarsus
merges the divides into four branches for the digits to insert
innervated by tibial branch of sciatic nerve
which spinal nerves supply the hindlimb?
L5, L6, L7, S1, S2
dorsal branches to dorsal structures, ventral branches to lumbosacral plexus
what kind of nerves is the gluteal nerve and where does it run?
motor only
runs over dorsal surface of ilium
what kind of nerve is the obturator nerve and where does it pass?
what muscles does this nerve supply?
motor only
passes through obturator foramen down to medial thigh
muscles- adductors so GAPE
gracilis, adductor, pectineus, external obturator
what kind of nerve is the femoral nerve and where does it pass?
what muscles does this nerve supply?
motor and sensory
motor to cranial thigh muscles (hip flexors and stifle extensors), iliopsoas, sartorius and all heads of the quadriceps
what reflex is the femoral nerve involved in? what happens after damage of this nerve? what is it sensory to?
patellar reflex
cannot extend stifle (no weight bearing), loss of patellar reflex
sensory to saphenous branch, including the femoral triangle
what kind of nerve is the sciatic nerve and where does it pass?
what muscles does this nerve supply?
motor and sensory
runs over dorsal surface of body of the ilium, passes caudal to hip and runs beep to biceps femoris
what is the sciatic nerve motor to?
caudal thigh muscles
hip extensors
stifle flexors - biceps femoris, semitendinosus and semimembranosus
what are the branches of the sciatic nerve?
tibial and fibular
what is the tibial nerve motor to?
caudal crural muscles
hock extensors - gastrocnemius
digital dlexors - superficial and deep
what is the tibial branch of the sciatic nerve sensory to?
caudal/plantar aspect of limb
what is the fibular branch of the sciatic nerve motor to?
cranial crural muscles
hock flexors - cranial tibial and peroneus group
digital extensors - long and lateral
what is the fibular branch of the sciatic nerve sensory to?
cranial/dorsal limb and lateral thigh
what can happen if the sciatic nerve is damaged?
lose supply to hip extensors/stifle flexors, hock extensors/digital flexors, hock flexors/digital extensors and lose sensation to all limb except medial thigh
can still abduct, adduct and flex hip/extend stifle
what are the two main arteries of blood supply to the hindlimn?
external iliac artery, which leaves the aorta to become the femoral artery
what is the order of arteries in the hindlimn?
external iliac, femoral (gives off saphenous for superficial supply to paw), popliteal, cranial tibial (deep supply to paw)
where is lymphatic drainage in the hindlimb?
in the popliteal area, caudal to the stifle
