Finding Bony Landmarks Flashcards
Fascial crest
You can see it without feeling it. Stand off to one side facing the horse’s head. You will notice these long prominences on either side of the face.
Nuchal crest/Occipital ridge
While standing off to one side, feel for the bump(s) in between the ears.
Mandibular ramus
This ridge is easy to feel along the back (caudal edge) of the lower jaw (mandible).
Nasoincisive notch
This is the notable junction where the incisive bone meets the nasal bone. With your finger pads placed behind the nostrils, gently move back (caudally) until you feel the notch. An alternative approach it to rest your finger pads on either side of the nasal bone and
slide forward (cranial) until you fall into the
notch.
Orbital rim
Caution must be taken here so you do not poke the horse in the eye. It is best to stand at the side of the horse’s head, about where the ears are, and face forward. To feel the upper (dorsal) portion, rest your inside hand on the horse’s forehead so your finger tips are facing downward. Gently feel the ragged edge with your thumb. You will find using this position keeps your hand in place in case the horse moves. To locate the lower portion of the orbital rim, rest the same hand
in a loose fist position on the lower jaw (mandible) so your little finger rests against the jaw. This again stabilizes your hand should the horse move. Using the side of your index finger so you are not pointing at the eyeball, rest on the edge of the lower edge of the orbit to explore.
Zygomatic arch
With your hand pointing the same way as the last exercise, rest your fingers on top, and your thumb below, on the prominence just behind the eye. Gently
explore.
Mandibular process or condyle process
Below the zygomatic arch is a small projection, which
is the mandibular process. If you are careful, you will feel a small gap that separates the zygomatic arch and the mandibular process. This is where the upper skull (maxilla) joins with the lower skull (mandible). This joint
space is the temporomandibular joint (TMJ).
Coronoid process
As you watch a horse chew, you will notice movement above his eyes. Rest your hand on the horse’s forehead and spread your fingers to rest on one side above the zygomatic arch with your thumb on the other side, just above the zygomatic arch. If you feed your horse a tidbit and you keep your weight of touch very light, you will feel the coronoid processes moving
Wing of Atlas
Place your fingers behind the base of the ears. Move them backwards (caudally) until you come to an obvious, bony enlargement. This is the wing of the
atlas (C1). If you ask the horse to lower his head, you will see this process. There will be a space in between the wing of atlas and the jaw. You can also try rest your hand on the horse and use your thumb to locate the wing as shown here.
C5
If you place your hands on the lower portion of the neck at its widest part these are easily felt. It is easier to see if you step to the front of the horse and off to the side facing the hind end and incline the neck
away from your body. Sometimes it helps to squat and look up at it, just mind your safety. Usually C5 is the most prominent bone from this view. C7 is usually covered by the bridging neck and shoulder muscles.
Scapular cartilage
Place your fingers on the higher portion of the withers, ease down with a very light pressure until you feel a change of texture; your finger will glide across the cartilage. Make sure you are moving perpendicular to the edge so you run over it. This dorsal edge is much easier to see if you lower the head and neck.
Scapular spine
Lay four fingers perpendicular to where you imagine the scapular spine to be. If you rest your hands on the shoulder, it will allow you more control with less effort. Run your finger pads across as if you were running over a speed bump. Make sure you are using a lightweight touch. Some breeds tend to have so much muscling that the spinatus muscles project beyond the spine lying deep between the muscles. Other lighter breeds or those with less shoulder muscling appear to
have a scapular spine that sticks out.
Humerus: cranial and caudal divisions of the major tuberosity
Some reference this prominence as the greater
tubercle. The cranial portion is actually, what a layman calls the “point of shoulder”. The “corner” of the horse’s shoulder is the cranial portion’s edge. Stand next to the horse’s shoulder and face forward. Using the outside hand, reach around your body and rest your hand on the chest. Draw your fingers towards the side of the shoulder from the corner of the shoulder. The first slight bump you run across is the cranial portion of this landmark. If you continue back (caudally) and upwards (dorsally) you will feel a small groove before you run across a second bump which is the caudal portion of the major tuberosity.
Deltoid tuberosity
If you look at the front limb, you will notice that the muscling makes an “A” as shown circled in red. From the same position used in the last check, place the fingertips of your outside hand on the apex (the upper point) of the “A,” making sure your fingertips point downward. From there, move your fingers forward (cranially) and feel for the edge of the deltoid tuberosity. Quite a bit of muscling is in the area so it will not be very prominent; think of feeling for the area that does not yield.
Radius; lateral proximal tuberosity
On the painted horse, this is the white area about
six inches behind the “A” you just located. Step towards the horse’s head. Turn around to face the hind end and rest your inside hand on the neck. The lateral head of the triceps (the light purple muscle below the large pink long head triceps muscle on the painted horse) makes a distinct line. Run your fingertips along this line and you will run over a bump, which is the lateral radial proximal tuberosity. Do not be afraid to go beyond the bump so you are sure of its location, you can always back track!
Olecranon
Take your hand off the neck, reach around the back of the leg (coming in from the outside), and gently wiggle the chestnut on the medial (inside) surface. This will
encourage the horse to unlock his leg. In doing so, the olecranon will show its point and you do not even have to bend over to pick up the leg! Your outside hand is free to feel for it.
Accessory carpal bone
This is one of the easier things to feel on the leg. Run your hand down the back of the limb and at the level of the carpus (the “wrist” of the horse which laypersons call the “knee) and you will feel the hard surface of the accessory carpal bone.
Styloid processes
If you step to the front of the horse (stay off to the side slightly for safely) and look at the carpal joint (layman’s knee) you will notice a projection on the lateral (outside) and medial (inside) surface of the leg. Still standing slightly off to the side, let a hand rest on each of these. Slide down and just as you fall off the projections, you are on the styloid process
Fourth metacarpus; lateral splint bone; proximal end or base
Just as the third metacarpus (cannon bone) widens, you will find a slight projection. It is best felt if you run
across the bone perpendicularly. Sometimes it is easier to pick up the seam between the cannon bone and lateral splint bone lower and then follow it upward.
The structure lying behind (caudal) the cannon bone and splint bone is the suspensory ligament. It may feel like bone when the horse is bearing weight, but will have slack when you pick up the leg and palpate.
Fourth metacarpus; lateral splint bone; distal end
It is easier to feel this down the back (palmar) edge of the cannon bone since it is not very prominent. Sometimes it is difficult to feel this on the outside (lateral) surface, but is typically simpler to feel on the inside (medial) splint bone, which is the second metacarpus.
Proximal sesamoids
Check for the area yield minimally at the back of the fetlock. Let your index finger cradle the back of the fetlock. There is a broad ligament (annular) which encases and covers these so they are not distinct when the horse is weight bearing. You can also try locating these by picking up the limb and letting your thumbs rest lightly against the back of the fetlock. If you open and close the fetlock joint a few times (fl ex
and extend), you will feel structures sliding over the sesamoids
When you pick up the limb, think about resting your outside arm on your outside limb. This protects your back and offers the horse support and confidence. Again, check in that your thumbs rest lightly (about the
pressure you would use on your eyelids) so you can feel the sesamoids under the surrounding structure. Note that the little fingers of the hands are as close as possible to the band where the top of the hoof meets
the hair of the limb. The little fingers bend the fetlock by lifting the hoof.
Shelf of ribs
You will be able to find this shelf, even on horses that fill out their skin well, by starting below the shelf about mid barrel (trunk). Running upwards (dorsally), your fingertips will hook the shelf.
Last rib
Again, this is easy to find on all body types. However, please think about your safety. By standing closer to the shoulder, you can see if the horse objects and starts to kick with the hind leg. You’ll start in front of what lay people refer to as the “point of hip” (coxal tuberosity) where the hair swirls in the flank area. While standing closer to the shoulder, reach with your outside hand and rest your fingertips midway on the
“flank swirl”. Now, draw your fingers towards yourself (cranially) and you will bump up against the last rib.
Transverse process of the lumbar
This is an area that is more of a suggestion. It is difficult to feel on most horses and best to find it by falling off the edge of the processes. The transverse processes run about the same level as the shelf of the ribs. Check for them beyond the last rib at the level of the shelf.
Sternum
This landmark can be difficult to find the first time until you know what it feels like. Thoroughbred type horses tend to have a “canoe” shape to the chest and you can see exactly where the sternum lies. There are two methods to finding this landmark. The first way begins with placing your fingers in the crease of the pectoral muscles (this crease is covered by the hand in the photo and lies ventral). Run up the crease until you find on a ledge. This ledge is the tip of the cartilage of the sternum (manubrium) and the landmark we are
targeting. The second way is accomplished by resting your palm above the shown hand position in the photo and running it down until you land on the tip of the sternum.
Sacral tuberosities
On some horses these are quite apparent, especially if they are a bit underweight or in below average condition. Lay people refer to this as the “point of croup”. If there has been an insult to the joint that connects the pelvis to the spine (sacroiliac joint), causing a disruption to the joint ligaments, the tuberosities may appear to be higher or uneven and the lay term “hunter’s bump” is used. To find these, run your hand down the spine so your fingers are all on one side and your thumb on the other side using light pressure. Your fingers and thumb will go wider as you run past the tuberosities. Once you locate this wider area, place your fingers on the centre of the spine and move towards your body. You will feel a small area where the tissue does not yield as much. This is the sacral tuberosity that lies on the side you are working. If you find this difficult, try it on a horse with a
prominent sacral tuberosity so you get idea as to how these feel when they are covered by tissue.
Some people also find it easier run your palm crossing perpendicular to the spine and bumping into
it that way instead.
Coxal tuberosity
The widest projection of the pelvic bone is the coxal tuberosity. Lay people refer to this as the “point of hip”. Please note this is not the hip joint. Find the top portion of the coxal tuberosity first and then explore its edges.
Ischial tuberosity
The point of buttock is formed by this tuberosity. The firm hamstrings cover it making it more difficult to feel. If you cock your wrist and run to the point of buttock, you land on the tuberosity. Slip over the bone and press up with your palm to locate the bottom edge. Sometimes can be felt from the medial surface
Femur; greater trochanter
Several muscles cover this landmark and it is typically easier to find cranial portion of the trochanter
as you zero in on the area. Start in the position shown below by locating the coxal tuberosity edges. Let the tuberosity go and allow your palm to rest behind the landmark. Begin pressing caudally with your palm
towards the point of buttock. You will notice that the palm does not sink as far inward as you run towards the cranial portion of the greater trochanter. Check slightly behind this (caudally) and upward (dorsally) so
you can catch the caudal part of the greater trochanter.
Third trochanter
You will know you found this landmark after you run past it the first time. Draw a circle around the greater trochanter. We will call this the “hip joint circle”. You will want to stay out of the circle for this run. Also, note the “dimple” of the stifle. Keep your fingers pointing forward for this entire run and allow your palm to do the search. Start on the rump and run the line towards the dimple of the stifle. About a third of the way on the portion of the line from the circle to the dimple you will fall off something firm. That is the third trochanter
Femur; lateral trochlear ridge
Before you begin exploring this area, make sure the horse is comfortable and desensitized. Some really
object and may kick. The lateral trochlear ridge is typically found below (ventral) and to the side (lateral) of the dimple of the stifle. Come in slowly to the area with distinct contact so the horse does not confuse you with a fly. Once you are close to the dimple drop down then let your fingers move out to the side. Here
you will feel an almost vertical ridge.
Patella
From the last position, slide your fingers across the dimple area staying cranially. The best way to find the patella for the first time is by asking the horse to take a step forward with your hand resting across the dimple area. As always, think about safety first before you attempt the exercise.
Tibial crest
Stand at the horse’s barrel and face the hindend. Rest your fingers as shown when the leg tapers inward. You are on the crest already, more specifically on the “tuberosity” of the crest. A portion of the crest runs craniomedially (from the front to the inside). There will be a space behind the crest and if you continue you will bump into the cranial edge of the lateral tibial condyle.
Tibia; lateral condyle
Begin as you did for the crest of the tibia. Lead with your middle finger running caudally. You will feel the same and then hit the cranial edge of the lateral tibial condyle. It is a good idea to run beyond the tibial condyle a few times, so you appreciate the edges.
Tibia; lateral malleolus
Keep your contact from the last position and slide down the leg. Just above the hock, you will be airborne. You just jumped off the lateral tibial malleolus.
Talus; lateral trochlear ridge
As soon as you landed after coming off the tibial malleolus, you were on the talus bone of the hock (tarsus). The talus is a component of the hock joint. The bone itself looks like a spool of thread on its side. It is fairly easy to feel both the lateral (outside) and the medial (inside) ridges of this bone. Note the lateral
tibial malleolus above the hock.
Calcaneal tuberosity
This is an easy one since you can actually see it. Lay people refer to it as the “point of hock”.
Fourth metatarsus; lateral splint bone; proximal end
You will check this the same way you did in the forelimb. Just as the third metatarsus (cannon bone) widens you will find a slight projection. It will lie more
rearward than the head in the front end.
Fourth metatarsus; lateral splint bone; distal end
It is easier to feel this down the back (plantar) edge of the cannon bone. It is not very prominent and sometimes it is difficult to feel this on the outside (lateral) surface, but typically simpler to feel on the
inside (medial) splint bone which is the second metatarsus.
Proximal sesamoids
You will check these bones the same way you did the forelimb. Again, please use caution back here. Check
for the area yield minimally at the back of the fetlock. Let your index finger cradle the back of the fetlock. There is a broad ligament (annular) which encases and covers these so that they are not distinct when the
horse is weight bearing. You can also try locating these by picking up the limb and letting your thumbs rest lightly against the back of the fetlock. If you open and close the fetlock joint a few times (fl ex and extend), you will feel structures sliding with the sesamoids.
