1. Stay Apparatus

2. Fore limb Stay Apparatus
The “Stay Apparatus” allows the horse to remain standing while relaxed or “catnapping”.
The Stay Apparatus and the Suspensory System share some of the same features.
The Scapula is held in extension by the Serratus Ventralis Muscles, the Supraspinatus and the Biceps and Triceps Brachii.
The Humerus by the Biceps Brachii and the Triceps Brachii.
The Radius and Ulna and 3rd Metacarpal being on a vertical line require slight tension on the the Lacertus Fibrous and the Extensor Carpi Radialis to ensure the Carpal joint remains closed.
The distal portion of the Stay Apparatus is made up of the Suspensory Ligament, the Flexor Tendons and their respective Check Ligaments. The Distal Ligaments of the Proximal Sesamoids and the ligaments of the Distal Sesamoid.
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3. Extensor Carpi Radialis Radial Check Ligament
Serratus Ventralis
Biceps Brachii
Lacertus Fibrous
Extensor Carpi Radialis
Radial Check Ligament
Superficial Flexor Tendon
Deep Digital Flexor Tendon
Sub-Carpal Check Ligament
Triceps Brachii
Supraspinatus Muscle
Suspensory Ligament
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4. H I
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5. Stay Apparatus of the Hind Limb
As with the fore limb, the Stay Apparatus of the Hind allows the leg to be locked; Allowing the horse to relax or sleep while standing.
This is accomplished by a slight upwards movement of the Patella by the Quadriceps Femoris Muscle. The Medial Patella ligament then slides over the medial tuberosity of the distal end of the Femur allowing the muscle to relax.
The weight of the horse is now borne on the Patella ligaments.
The Peroneus Tertius Muscle, (comparable to the biceps of the fore limb), originates on the distal cranial face of the Femur and inserts on the proximal face of the 3rd. Metatarsal.
This is opposed by the Gastronemius and the mostly fibrous Superficial Flexor Muscle, both of which attach to the point of the hock.
These tissue and those of the Fetlock then cause the Stifle, Hock and Fetlock to flex in unision.
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6. Superficial Flexor Tendon
Tensor Fascia latae
Patella Ligaments
Peroneus Tertius
Superficial Flexor Tendon
Gluteal Muscles
Biceps Femoris Muscle
Same as fore below hock
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7. A B C D F E
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