The aura of the replica: polyurethane models of horse foot anatomy

Montage of model stages, with painted palette.

3D Vet Anatomize have brought together an international team of veterinary imaging and computer modelling specialists to provide unique anatomical replicas of the horse’s foot to meet your specific learning, teaching and demonstration needs.  Colour it yourself and learn the anatomy as you go.

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As you colour the various ligaments and tendons, you will quickly learn and remember their precise shape and size and their points of origin and attachment on the skeleton.  For example, you will see how the distal branches of the superficial digital flexor tendon bifurcate and insert on both the distal proximal phalanx and proximal middle phalanx.  This is an excellent way to learn and remember the complex anatomy of the equine distal limb. You will come to appreciate the mechanics of joint flexion and extension and how the soft tissue structures are located on the bones specifically to accommodate the enormous loads of weight bearing and locomotion. If you own the model you colour it will remain excellent for revision  and a tool for communicating to students and clients details of equine foot anatomy.      

As you colour the structures you will come to realize that the bumps and valleys on the bones are not random but specialised zones for strong attachment of ligaments and insertion of tendons. There are fossae (shallow cavities) on the bones for the integration of ligaments (the distal interphalangeal (coffin) joint collateral ligaments are a good example of this) and roughened, reinforced zones for the insertion of tendons (eg. the insertion of the deep digital flexor tendon on the palmar aspect of the distal phalanx).

Not a preserved dissection but a dry, clean, anatomically correct, polyurethane model derived from genuine, high resolution CT and MR data. Ideal for display, education or instructive purposes, the models are life size and anatomically accurate. All the models are generated from actual imaged anatomy; there is no artistic interpretation of structure. 

The original 3D printed models (the masters) were embedded in two part silicone moulds. Liquid polyurethane, poured into the mould sets up in 5-7 minutes resulting in rigid, light-weight, hollow polyurethane casts.  The master 3D printed models are unique and costly to produce (several hundred dollars). In contrast, the polyurethane models are relatively economical after the expense of the silicone mould has been accounted for.

Choose one or more of our existing, plain white polyurethane models and using the chart provided, colour it yourself learning the anatomy as you go.
Each anatomical item (except the plain white bones) is coloured separately. The task of colouring the tendons and ligaments can be completed in about 20 minutes. For example the distal interphalangeal (coffin) joint collateral ligaments are coloured mid-green, the deep flexor tendon is light brown and so forth. You can colour with water-based Texta Pens (Nylorite 24 colours) and simply wash away the result, enabling another student to complete the task after you.  For a more permanent result, a 24 pack of coloured Sharpie Pens may be used. Solvent based and fast drying, these pens leave indelible colour. Time consuming, but artistically more satisfying, is the use of acrylic paints. From a 12 tube pack of student acrylic paints (Chroma A2 Lightfast Acrylic) all the pastel shades of the colour chart can be matched and applied to the model. Broad brushes are recommended for large area application and fine small brushes for the smaller, more detailed parts. A hair dryer speeds drying of the paint. For more information on colouring the models view this video.

A learning plan

An ideal learning plan would be to purchase model DLB: consisting of just the bones of the distal limb. Learn the names of the bones and joints and study the fossae, tuberosities and processes. Think about where the ligaments and tendons must insert on the bones to not only hold the foot together but make it function.

The chart provided for studying the bones of the distal limb; exploded, dorso-palmar view

Next purchase model DLBLigs: the bones plus the major ligaments of the distal limb. Study where the ligaments attach and insert comparing with the bones only model. Note how each bony fossa, process and tuberosity has a function that relates to a ligament or tendon.

Using the chart, colour in the structures, naming them and noting their size and location as you go.  The model features a detachable straight sesamoidean ligament that can be painted separately before fitting into place. This enables study of the underlying cruciate, short and oblique sesamoidean ligaments.

Note how the collateral ligament of the distal sesamoid bone (the navicular suspensory ligament) inserts over the entire proximal border of the navicular bone and its medial and lateral branches pass around the middle phalanx and attach on the dorsal, distal surface of the proximal phalanx.    

The colour chart provided for studying the sesamoidean and collateral ligaments of the distal limb model DLBLigs0001

Next in the study plan purchase model DLBLigsTends, consisting of the bones, the major ligaments and additionally the flexor and extensor tendons of the distal limb.  As you paint and study the tendons, note how the superficial digital flexor tendon bifurcates mid-pastern forming a medial and a lateral branch. The deep digital flexor tendon (DDFT) passes through the bifurcation, continuing on to insert on a roughened zone on the palmar, distal phalanx. In the model, the DDFT is cut in the sagittal plane to show the close apposition of the tendon to the flexor surface of the distal sesamoid (navicular) bone. The branches of superficial flexor tendon each have two terminal branches with one branch inserting on the distal end of the proximal phalanx and the other on the proximal end of the middle phalanx.   

The colour chart provided for studying the ligaments and tendons of model DLBLigsTends0001.

Finally glue the separate ungual cartilage in place and insert the complete distal limb model into its matching hoof capsule (model NHHCap0001). On a flat surface, the two models will stand alone.

The complete, hand-painted distal limb model (DLBLigsTends0001) placed inside its matching hoof capsule (model NHHCap0001)

* Reference: The Illustrated Horse’s Foot: A Comprehensive Guide. by Emeritus Professor
Christopher C. Pollitt, Elsevier, St Louis. ISBN:978-0-7020-4655-1