B4L3: LA Thoracic Limb: Passive Stay Apparatus and Fibrous Support

How do large animals oppose gravity without expending lots of energy?

downward force due to weight of the body

Functions of the stay apparatus

- reduce the energy required to stand

- make movement efficient conserving energy

Describe the Stay apparatus

- allows horse to doze while standing up, using minimal muscular activity\

What percentage of weight is on the thoracic limbs?

60%

Glenohumeral joint correlates to

shoulder joint

Humeroradioulnar joint correlates to

elbow joint

Layman's term of metacarpal III

cannon bone

Layman's term of metacarpal II and IV

splint bones

Layman's term of the carpus

knee

What joints make up the carpus?

- antebrachiocarpal joint

- middle carpal joint

- carpometacarpal joint

Layman's term of the proximal interphalangeal joint

pastern joint

Layman's term of the interphalangeal joint

coffin joint

Layman's term of the metacarpophalangeal joint

Fetlock joint

The body weight is transferred to the limb via what muscles?

pectoral muscles and serratus ventralis

What prevents the shoulder from flexing

tendon of the biceps brachii

Where does the bicep tendon lock on the humerus

intermediate tubercle

- makes the shoulder joint unable to flex

- tendon distance is fixed , cannot increase

When the shoulder is locked, body weight is balancing on crooked post, what helps make corrections if necessary to keep balanced?

tricep muscle

What happen to the Extensor carpi radialis muscle during the flexion of the carpus?

elongation of the ECR is required

What part does the lacertus fibrosus play on the thoracic limb of the horse?

transmits the tension on the biceps brachii m. to the extensor carpi radialis m.

- carpus cannot flex unless ECR m. is relaxed

What part does the palmar carpal ligament play on the thoracic limb of the horse?

- prevents hyperextension of the carpus joints

- dorsal border of the carpal canal

What counteracts the downward force on the fetlock joint?

Proximal and distal check ligaments

What "checks" the tension on the tendons of the SDF and DDF

- the accessory ligaments of these tendons

What ligament is stretched with the downward force on the fetlock?

suspensory ligament ~ interosseous ligament

What covers the proximal sesamoids?

scutum

Origin on the interosseous lig.?

proximal metacarpus

insertion of the interosseous lig.

proximal sesamoids

- extensor branches joint the common digital extensor tendon

What are the 3 sesamoid ligaments?

- straight

- oblique

- cruciate

What is the role of the sesamoidean ligaments?

inhibit hyperextension of the fetlock joint

Origin of the sesamoidean ligaments

proximal sesamoid bones

insertion of the sesamoidean ligaments

proximal phalanx