IMSK Final MK Review Flashcards
ID parts of the ear
External: pinna, vertical canal, horizontal canal, tympanic membrane
Middle: tympanic bulla (bony septum, 2 compartments in cats), ossicles, vestibular window
Inner: vestibular organ (balance), cochlea (hearing organ)
describe the phases of the hair growth cycle
Anagen: growth phase; cells mitotically active, melanin production increases
Thyroid and growth hormones increase the activity of this phase; glucocorticoids and estrogen decrease the activity of this phase
Catagen: regressive/resting phase; mitotic activity decreases and then ceases
Caspase activity and keratinocyte apoptosis increases and melanin production decreases
Telogen: resting phase; follicle eventually cycles back to mitotically active
Small dermal papilla and no mitotic activity
Exogen: shedding before returning to anagen
list the layers of the skin and what they contain
Epidermis: primary envelope containing water, electrolytes, and macromolecules like protein, carbohydrates, and fat; also melanocytes, intraepidermal macrophages, merkel cells
Dermis: fibers (mainly collagen) + polymers (proteoglycans and hyaluranan)
Fibers resist pull/tensile forces and polymers resist push/compression forces
Subcutis/hypodermis: protective padding of skin, mainly adipose tissue
Same thing as midterm just adjusted, same label pic- Layers of skin: epidermis, dermis, subcutis
describe the cell membrane
phospholipid bilayer, hydrophobic molecules can diffuse right through but charged molecules like ions require channels
describe membrane potential and what contributes to it/how ions move
cell resting potential is more negative, so potassium (K+) is kept inside by attraction to the negative;
there is usually more K+ inside the cell than outside and it wants to move out of the cell via its channels;
There is usually more sodium (Na+) outside of the cell than inside and it wants to move inside the cell via its channels
There is usually more chloride outside the cell than inside (Cl-)
There is not much calcium inside or outside of the cell at rest. Since it is Ca2+, it really really wants to move inside the cell. It is a very large molecule though so it can sometimes block sodium channels (how some anesthetics work)
describe voltage and ligand gated ion channels
Voltage gated channels open and close in response to changes in membrane potential
Ligand gated channels open when a chemical ligand binds to the protein
describe depolarization
Leaky sodium channels slowly bring membrane potential to threshold
Once threshold reached, voltage-gated sodium channels fly open, rapid (+) influx, membrane depolarizes and action potential is propagated
K+ channels open and rapid efflux of (+) leaving cell hyperpolarizes
describe absolute refractory period
Absolute refractory period is when the membrane cannot produce another action potential because sodium channels are inactivated or blocked; is important because when an AP is propagated, it sets up a local current that could travel both forward and backward bc physics, so the absolute refractory period ensures that the AP only moves forward
describe hypokalemia
If have low extracellular potassium, the excess potassium would rush out of the cell, causing the cell to hyperpolarize and decreasing excitability; can be caused by diuretics, vomiting, diarrhea, and diabetes
describe major differences in skeletal/cardiac/smooth muscle in the context of myasthenia gravis
myasthenia gravis only affects the skeletal muscle and in very rare cases will affect the cardiac muscle
Myasthenia gravis destroys the communication network between muscles and nerves in skeletal muscle
Acetylcholinesterase typically breaks down acetylcholine in the synapse, allowing responses only when there is an action potential
If a drug blocks acetylcholinesterase, acetylcholine will stay in the cell and the muscle will continue to contract, which can be useful for myasthenia gravis patients (acetylcholinesterase inhibitors)
describe the effects of monoamine oxidase
Monoamine oxidase
Degrades epinephrine, norepinephrine, and dopamine
When inhibited via MAOIs, there is an increased amount of neurotransmitters left in the synapse
Since there is an increase in norepinephrine, looks like there’s sympathetic activation
Because there is more norepi available to bind to adrenergic receptors and cause a response. Same mechanism as acetylcholinesterase inhibitor effect on acetylcholine.
describe generation of skeletal muscle tension
Contracting from resting length will generate the most muscle tension
If contract from an extended position, not as much interaction between thin and thick filaments
If contract from already somewhat contracted position, thin and thick filaments have too much interaction and can’t shorten farther than their capacity
what is stringhalt and how is it fixed?
Stringhalt- high stepping gait and abnormal and exaggerated flexion of the hock due to neuropathy of the lateral digital extensor
Remove the entire belly of the lateral digital extensor and allow long digital extensor to take over to fix
describe fibrotic myopathy in equines
Damage to the semi-muscle complex (biceps femoris) leads to
Scar tissue formation that limits extension;
decreased range of motion, will see foot swing forward and then snap back on/to ground
what structures connect the femur to the tibia?
Medial and lateral collateral ligaments
Medial, intermediate, and lateral patellar ligaments
describe the trochlear groove of the femur
This groove is significant because the patella can get stuck on top of the medial trochlear ridge during movement, can cut the medial patellar ligament to unlock patella and return motion
describe the reciprocal aparatus
Peroneus tertius originates from femur and extends across the tibia to metatarsal region
Works with the SDF to ensure that hock and stifle are either synchronously flexed or extended
give the major flexors of the stifle joint
Biceps femoris- inserts on tuber calcanei
Semimembranosus- inserts on medial tibial condyle
Semitendinosus- inserts on tuber calcanei
gastrocnemius and SDF help too (tibial nerve)
All innervated by sciatic nerve
give the major flexors of the hip joint
Iliopsoas- inserts on lesser trochanter
Rectus femoris- inserts on tibial tuberosity through the patellar ligament
Both innervated by femoral nerve
describe the attachments of the cruciate ligaments
Cranial cruciate- attaches at the cranial aspect of tibial intercondyloid space
Caudal cruciate- attaches at the caudal aspect of tibial intercondyloid space
describe tibial nerve damage
Extension of hock and digit flexion is affected
Signs and symptoms include a sunken walk and animal possibly walking plantigrade (with foot flat on ground)
describe fibular nerve damage
Is motor to the flexors or tarsus and extensors of the digits (cranial tibial, long digital extensor, peroneus longus)
Sensory to skin on craniolateral surface of the leg, tarsus, paw
Damage affects straightening of the hock and knuckling over the digits
Signs will be of animal having difficulty extending digits
a fibular fracture is the most common cause of damage to the fibular nerve (over the lateral head of the gastrocnemius)
where to be careful when giving IM injections?
between muscles of the caudal thigh;
Damage to sciatic nerve if injected into the groove between muscles
Isolate the muscle belly and inject there
describe the obturator nerve (4)
Located in the cranial part of the obturator foramen, medial to the surface of the adductor muscle on the inside of the thigh
Motor supply to external obturator and all medial thigh muscles (PAGE) except sartorius (femoral nerve does sartorius)
NO CUTANEOUS INNERVATION
Damage results in difficulty adducting the limb and commonly occurs during parturition in large animals (see sad splits cow)
describe the femoral nerve (4)
THE MOST IMPORTANT NERVE- weight bearing
INNERVATES THE MOST IMPORTANT WEIGHT BEARING
MUSCLE (quadriceps femoris)
Moto supply to iliopsoas and quadriceps femoris
Damage: unable to bear weight on stifle
what is done anatomically in TPLO?
Change the angle of the tibial plateau to prevent backwards shift of the femur
what structures cut during FHO?
Head of the femur, neck of the femur, and ligament of the head of the femur
what 2 veins are commonly used for venipuncture in dogs?
Lateral saphenous vein
Cephalic vein
describe movement associated with the tarsal joints
Tarsocrural joint is the high motion joint of the hock
The others are low motion and do not flex or extend
Function is absorption
Top two joints communicate in tarsus:
tibiotarsal/tarsocrural and proximal intertarsal joints
what 2 structures originate from the extensor fossa?
Long digital extensor
Peroneus tertius
describe the canine stifle joint
Five joints:
Femorotibial, femoropatellar, proximal tibiofibular, joint between femur and gastrocnemius sesamoids, joint between lateral tibial condyle and popliteal sesamoid
One patellar ligament
Two collateral ligaments and two cruciates attach femur to crus
Medial and lateral femoropatellar ligaments hold patella in place
describe the equine stifle joint
Lack sesamoids in gastrocnemius and popliteus
3 patellar ligaments
Lateral, middle, and medial
Medial and lateral femoropatellar ligaments hold patella in place
what is common of both the equine and bovine stifle joints? clinical relevance?
All joints communicate- leads to problems when there is a joint infection or arthritis
what species has a sacrotuberous ligament?
Present in canines only, not felines or horses
what 6 (7ish) structures are innervated by the sciatic nerve?
Biceps femoris
Gluteobiceps (bovine)
Semitendinosus
Semimembranosus
Internal obturator
Gemelli
Quadratus femoris
if you place a rod to fix a femoral fracture and the rod slips proximally, what could happen?
If this rod shifted proximally, could cause damage to the sciatic nerve
If damaged, animal can still bear weight not confidently
Can still extend the hip and stifle due to intact obturator and femoral nerves
Hock will be unstable because of the tibial and fibular nerves
what structures are in the femoral triangle? what are the borders?
includes saphenous nerve, femoral artery, and femoral vein
cranial border is sartorius, caudal border is pectineus, lateral border formed by vastus medialis and rectus femoris
compare and contrast the origin of the SDF in large and small animals
Origin is from the medial and lateral supracondylar tuberosities in both large and small animal, but canines have gastrocnemius sesamoids in that spot, so the gastrocnemius originates from the sesamoids in pups
give muscles with common origins and their actions on joints
Middle and deep gluteals originate from ilium and both extend the hip and abduct the limb; all innervated by cranial gluteal nerve
The PAGE muscles (pectineus, adductor, gracilis, and external obturator) all originate from the ischium and all adduct the limb; all innervated by obturator nerve
Biceps femoris, semimembranosus, semitendinosus, (gluteobiceps in cattle) all originate from ischiatic tuberosity and all extend the hip, flex the stifle, and extend the hock (except semimembranosus who doesn’t extend hock due to its separate insertion (all sciatic nerve)
Vastus medialis, vastus intermedius, and vastus lateralis all originate from the femur and all extend the stifle (femoral nerve)
give location of trochanteric and cunean bursas
Trochanteric: sits under the middle gluteal muscle
Cunean- sits under the cunean tendon (medial insertion of cranial tibial muscle)
what muscles originate from lateral and medial epicondyle of humerus, insertion, innervation, result of damage to either condyle
Extensor carpi radialis (extends carpus)
inserts at dorsal side of MC 2 and 3
Innervated by radial nerve
Common digital extensor (extends carpus and digits)
Inserts on distal phalanges 2-5
Innervated by radial nerve
Lateral digital extensor (extends carpus and digits)
Inserts on distal phalanges
Innervated by radial nerve
Supinator
Inserts on mid-proximal radius
Innervated by radial nerve
Medial condyle:
Superficial digital flexor (flexes carpus and digits)
Inserts on P2
Innervated by median nerve
Flexor carpi radialis (flexes carpus)
Inserts on palmar MC 2+3
Innervated by median nerve
Deep digital flexor (flexes carpus and digits)
Humeral head
Inserts on P3
Innervated by median nerve
Ulnaris lateralis (flexes carpus)
Inserts on accessory carpal bone
Innervated by radial nerve
Lateral condyle fracture:
Loss of carpal and digital extensor muscles
No extension of the carpus or digits
Medial condyle fracture
Loss of carpal and digital flexors
No flexion of the carpus or digits
Will still have the ulnar and radial heads of the deep digital flexor tendon, could have still some flexion
what 2 structures attach to accessory carpal bone?
Flexor carpi ulnaris and ulnaris lateralis attach to this bone and will be useless if fractured
what happens when you declaw a cat?
Lose function of deep digital flexor; function should still be fine thanks to SDF though
what happens if a feline fractures its supracondylar foramen?
Median nerve and brachial artery run through here; lose function of muscles innervated by median nerve if fractured (forearm flexors)
what happens to shoulder flexion if axillary nerve is damaged?
Axillary nerve innervates deltoideus, teres major, and teres minor (classical shoulder flexors)
If this nerve is damaged, the animal can still flex the shoulder via the long head of the triceps, which is innervated by the radial nerve
where can the radial nerve be damaged (2) and what would be the result?
If after the lateral head of the triceps, animal can still bear weight but will have knuckling
If before enter long head of triceps, no weight bearing or elbow extension
describe damage of radial, median, musculocutaneous, and ulnar nerves
Radial nerve:
Damage on the medial aspect = non-weight bearing
Damage on lateral aspect = knuckling
Musculocutaneous nerve:
Loss of biceps brachii, brachialis, and coracobrachialis
Will not be able to flex the elbow
Can still extend the shoulder via supraspinatus, infraspinatus, and subscapularis
Median nerve:
Complete loss of superficial digital flexor and flexor carpi radialis
Loss of humeral head of deep digital flexor
ulnar nerve: complete loss of flexor carpi ulnaris; ulnar head of deep digital flexor, mostly covered by median nerve though
compare and contrast gluteal muscle across species
All 3 extend hip and adduct limb
Cow doesn’t have superficial gluteal, has gluteobiceps (biceps femoris + superficial gluteal) instead
Superficial is innervated by caudal gluteal nerve and supplied by caudal gluteal artery
Middle and deep are innervated by cranial gluteal nerve and supplied by cranial gluteal artery
what structures contribute to the common calcanean tendon?
SaD Guys Buy STupid Gifts: superficial digital flexor, gracilis (does not extend tarsus), biceps femoris, SemiTendinosus, gastrocnemius
compare and contrast tarsal bones across species
Canine: 7 arranged in 3 rows
Proximal: talus, calcaneus
Middle: central
Distal: T1-T4
Equine: 6 arranged in 3 rows
Proximal: talus, calcaneus
Middle: central
Distal: fused T1+T2, T3, T4
Bovine: 5 arranged in 3 rows
Proximal: talus, calcaneus
Middle: fused central+T4
Distal: T1, fused T2+T3
function of navicular bursa?
Navicular bursa provides cushioning between navicular bone and deep digital flexor tendon
