Lesson 18 - ligaments & tendons of equine & ultrasound

Where is the origin of the superficial digital flexor muscle?

medial epicondyle of humerus

Where is the insertion of the superficial digital flexor muscle?

middle phalanx

Where is the origin of the deep digital flexor muscle?

medial epicondyle, caudal radius, caudal olecranon

Where is the insertion of the deep digital flexor muscle?

flexor surface of distal phalanx

Where is the origin of the interosseous muscle?

proximal end of metacarpal bones and joint capsule of carpus

Where is the insertion of the interosseous muscle?

proximal sesamoids, joins common digital flexor tendon

Where is the origin of the accessory ligament of superficial digital flexor muscle?

caudal radius

Where is the insertion of the accessory ligament of superficial digital flexor muscle?

superficial digital flexor

Where is the origin of the accessory ligament of deep digital flexor muscle?

palmar carpal ligament

Where is the insertion of the accessory ligament of deep digital flexor muscle?

deep digital flexor

What is the action of the accessory ligament of the superficial digital flexor muscle?

prevent over extension of the limb

What is the action of the accessory ligament of the deep digital flexor muscle?

prevent over extension of the limb

In the proximal palmar aspect of metacarpus, what is the most superficial structure?

superficial digital flexor tendon

In the proximal palmar aspect of metacarpus, what is the second most superficial structure?

deep digital flexor tendon

In the proximal palmar aspect of metacarpus, what is the second deepest structure?

accessory ligament of the deep digital flexor

In the proximal palmar aspect of metacarpus, what is the deepest structure?

suspensory ligament

What aspect of the metacarpus has the accessory ligament present?

accessory ligament of deep digital flexor

In the mid palmar aspect of metacarpus, what is the most superficial structure?

superficial digital flexor ligament

In the mid palmar aspect of metacarpus, what is the middle structure?

deep digital flexor ligament

In the mid palmar aspect of metacarpus, what is the deepest structure?

suspensory ligament

What is absent in the mid palmar aspect of the metacarpal?

accessory ligament of the deep digital flexor

Proximal to the fetlock region, what is the most superficial structure?

superficial digital flexor tendon

Proximal to the fetlock region, what is the second most superficial structure?

deep digital flexor tendon

Proximal to the fetlock region, what is the second deepest structure?

manica flexoria

Proximal to the fetlock region, what is the deepest structure?

suspensory ligament with two divisional branches

What is the deepest structure in the pastern region?

oblique sesamoidean ligament

What is the second deepest structure in the pastern region?

straight sesamoidean ligament

Where is the origin of the straight sesamoidean ligament?

base of proximal sesamoid bones and palmar ligament

Where is the insertion of the straight sesamoidean ligament?

middle phalanx

Where is the origin of the oblique sesamoidean ligament?

base of proximal sesamoid bones and palmar ligament

Where is the insertion of the oblique sesamoidean ligament?

proximal phalanx

What is the most superficial structure over the fetlock?

palmar annular ligament

What is the deepest structure at the level of the fetlock?

intersesamoidean ligament

What is the most superficial structure at the level of the pastern?

proximal digital annular ligament

What is the most superficial structure at the coffin region?

distal digital annular ligament

What is the second most superficial structure at the coffin region?

deep digital flexor tendon

What is an expensive diagnostic tool for tendons, soft tissue, or bone abnormalities?

magnetic resonance imaging

What is the diagnostic method of choice for assessing equine tendon injuries?

ultrasonagraphy

What are ultrasounds?

sounds over 20,000 Hz

What is frequency?

number of cycles per second

What is 1 hertz?

one cycle per second

How does wavelength change as frequency is higher?

sound wavelength is shorter

How does wavelength change as frequency is lower?

sound wavelength is longer

What type of probe has the shortest depth?

linear

What type of probe has the longest depth?

phased array

What is the probe of choice for ultrasounding equine limbs?

linear probe

Why is the linear probe best for equine limbs?

more frequency and less depth so that more details are obtained

Why does a higher frequency pick up more details?

more waves can pass through multiple areas of the tissues picking up more details

What type of frequency travels deeper into tissue?

low frequency

What type of frequency doesn't travel as far into the tissue?

high frequency

What are the properties of sound waves?

reflection, absorption, scattering, attenuation, refraction

What does all biological tissue do to sound?

cause impedance which influences the velocity of the sound

What tissues absorb ultrasound waves?

bone and minerals

What tissue reflects ultrasound waves?

air

What tissue refracts ultrasound waves?

air and tissues

What tissue scatter ultrasound waves?

small and irregular structures

What is attenuation?

weakening of sound traveling through medium because of reflection, refraction, scattering and absorption of heat by the tissues

How much sound energy is attenuated by air within 0.05cm with a 2.0 MHz transducer?

half of the sound energy

How are sound waves made into an image?

device detects the depth of the returning echoes and the time it takes to return

What are the modes of the ultrasound?

B-mode, M-mode, doppler mode

What is the b-mode also called?

brightness mode

What is the m-mode also called?

motion mode

What is b-mode?

ultrasound measures intensity of the returning echoes and expresses them in terms of pixel brightness on the monitor

What determines how a tissue looks on the ultrasound in b-mode?

normal appearance, tissue type, depth

What is echogenicity?

ability of a tissue to reflect sound waves and produce echoes

What tissues are the most echogenic?

bone and gas

What tissues are the least echogenic?

fluid like blood and urine

What is the term for brighter echoes?

hyperechoic

What is the term for low level of gray echoes?

hypoechoic

What is the term for black appearance on ultrasound?

anechoic

What is the most hyperechoic?

bone and gas

What is the second most hyperechoic?

connective tissue

What is slightly more hypoechoic than connective tissue?

fat

What is slightly more hypoechoic than fat?

spleen

What is slightly more hypoechoic than the spleen?

liver

What is the most anechoic?

blood/fluid

What is slightly more hypoechoic than blood?

renal cortex

What is m-mode?

one beam of sound that catches structures while they are moving and displays the movement in a one-dimensional plane to show how the structure moves over time

What is the doppler shift?

as you move toward a sound source the frequency will increase and vice versa

What is a pulsed wave doppler?

new sound waves will not be transmitted until the transducer has received the echoes from the previous burst

What is a continuous-wave doppler?

continuously sends out sound and continuously receives sound

What is color-flow doppler?

real-time iages and color-flow mapping at the same time

What is the rule of thumb for the color doppler?

blue away, red towards

What is an ultrasound artifact?

anything seen missing on the image that is in the wrong place, the wrong size, the wrong shape, or is missing

What can cause ultrasound artifacts?

improper use of machine, improper settings, poor patient preparation, misinterpretation

What is the region of ultrasound interest in equine forelimb?

just below the accessory carpal bone to below the fetlock

What is the region of ultrasound interest in equine hindlimb?

metatarsal region up to the chestnut

How does the site for ultrasound need to be prepped?

clipping, washing with chlorhexidine scrub, wetting using alcohol

What transducer should be used for the proximal suspensory ligament?

micro-convex transducer

What are the planes for ultrasound imaging?

transverse and longitudinal

What is the scanning order for ultrasounding legs?

start proximal and move distal and begin with transverse views

What are the zones for the forelimb imaging?

3 zones with 6 regions

What are the zones for the hindlimb imaging?

4 zones with 8 regions

How does shape of the SDFT change from the carpus distally?

oval to circular located palmaro-medial, then becomes concave crescent, then thins and forms a ring around DDFT

What is the shape of the DDFT?

oval

What is the shape of the interosseous ligament?

rectangular

What is the appearance of the interosseous ligament?

less echogenic, more heterogenous than the other tendons

What are the shapes of the interosseous ligament branches?

initially oval then become tear-drop more distally

What suggests an acute injury to tendons on ultrasound?

hypoechoic change due to edema/increased water content

What suggests a chronic injury to tendons on ultrasound?

hyperechoic change