Anatomy Lecture 3 Flashcards
What is the purpose of the stay apparatus of the horse?
Allows the horse to dose while standing up, using minimal muscular activity
- locks joints and limbs to prevent collapse
What is another name for the shoulder joint?
Glenohumeral joint
What is another name for the elbow joint?
Humeroradioulnar Joint
What are the names of the three joints in the Knee?
Antebrachiocarpal Joint
Intercarpal Joint
Carpometacarpal Joint
What is another name for the Fetlock?
Metacarpophalangeal Joint
What is another name for the Pastern?
Proximal Interphalangeal Joint
What is another name for the Coffin?
Distal interphalangeal joint
What are the muscles involved in the Fibrous support mechanism?
Tendon of the Biceps brachii, Lacertus fibrosus, Extensor carpi radialis, Triceps brachii, SDF and accessory (proximal check) ligament, DDF and accessory (Distal check) ligament, Common digital extensor tendon, Interosseus, Proximal sesamoid bones and sesamoidean ligaments.
The tendon of which muscle prevents the shoulder from flexing (stay apparatus)? How?
Biceps brachii - radial insertion of this muscle is a fixed point since its close to the axis of rotation of the elbow which is stabilized by the weight of the animal.
What allows the shoulder joint to lock (stay apparatus)
Molding of the biceps brachii tendon to the intermediate tubercle of the humerus
What acts to maintain the extension of the elbow when the actual muscle of the triceps brachii is flaccid? (stay apparatus)
The fibrous components within the muscles maintain extension
What muscle at the elbow joint remains engaged during the stance phase?
the anconeus
With the shoulder fixed, how does the weight rest?
on a nearly vertical radius
How is the stabilization of the shoulder achieved?
- biceps brachii maintains extension of the shoulder
How is the stabilization of the Elbow joint achieved?
- fibrous components within the triceps brachii maintain extension of the elbow
- Anconeus remains engaged during the stance phase
- smal corrections made by the carpal and digital flexors to maintain vertical radius of weight
How is the stabilization of the Carpus achieved?
- tension exerted on the tendon of the biceps brachii is transmitted to the extensor carpi radialis m. via the lacertus fibrosus. This exerts overall upwards force that prevents buckling
- Strong palmar carpal ligament also prevents hyperextension
Which muscles are involved in the stabilization of the fetlock, pastern and coffin joints?
- Suspensory apparatus: Interosseus (lateral and medial branches that unite with comon digital extensor), proximal sesamoids, sesamoidean ligaments (Straight, Oblique, Cruciate)
- SDF and proximal check ligament
- DDF and distal check ligament
How is the downward force on the SDF and DDF counteracted?
by the proximal and distal check ligaments respectively
What counteracts the flexing of the coffin joint?
the extensor branches of the interosseus
What counteracts the hyperextension of the fetlock?
the distal sesamoidean ligaments
Where do the distal sesamoidean ligaments attach?
distal attachments to the proximal phalanx, middle phalanx also attached to the middle phalanx
How are the structures of the suspensory apparatus able to “spring back” to their normal state so quickly?
they store energy
What is a digigrade?
walks/bears weight on digits
What is an Unguligrade?
walks/bears weight on the distal phalanx
What metacarpal bone is weight bearing in the horse?
the third metacarpal
What metacarpal bone is weight bearing in the Ox?
Third and Fourth metacarpals
Which metacarpal bones are the medial and lateral splint bones of the horse?
Medial: second metacarpal
Lateral: Fourth metacarpal
Which carpal bones are fused in the dog?
the radial and intermediate proximal carpals
Which carpal bones are fused in the horse?
The first distal carpal is either fused, very tiny, or non-existant
Which carpal bones are fused in the Ox?
The second and third distal carpal bones are fused and the first is missing
What muscle gives the horses shoulder a nice rounded appearance?
the subclavius m.
Which muscle on the horse forms the ventral border of the jugular groove?
the sternomandibularis m. (synonymous with the sternocephalicus)
Which digits are cut when amputating the digit in cattle?
the proximal and distal interdigital ligaments
What muscle has ruptured in a horse with a flying scapula?
serratus ventralis
Carpal bone II rests entirely on what?
the medial splint bone
Carpal bone IV rests on what?
both metacarpals III and IV
Where do popped splint lesions in the forelimb usually occur? What does it result in?
on the medial side - results in damage to the interosseus ligament
How are proximal sesamoid fractures accomplished?
the accessory bone gets pulled on so hard that pieces of bone rip off
