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Tendons - Horse Anatomy (view source)
Revision as of 12:34, 11 October 2012
, 12:34, 11 October 2012→Flexors
===Flexors===
===Flexors===
The digital flexor tendons are surrounded by synovial sheaths, which serve a protective function; allowing frictionless movement as the tendons traverse the bony prominences of the carpus and metacarpophalangeal (fetlock) joint.
*'''Carpal Sheath'''
Arises approximately 10cm proximal to the carpus and extends to mid-metacarpal region.
*'''Digital Sheath'''
Arises at the distal metacarpus, approximately 5cm proximal to the metacarpophalangeal joint and extends to the middle of the second phalanx.
'''''Superficial Digital Flexor Tendon'''''
*'''Origin''': Superficial digital flexor muscle on the medial humeral epicondlye
*'''Insertion''': Middle phalanx
*'''Action''': Flexes the proximal and middle phalangeal joints, stabilises metacarpophalangeal joint
The SDFT arises from the superficial digital flexor muscle at the level of the carpus. At this level, the tendon combines with the accessory ligament ('''superior check ligament'''). The tendon passes distally on the caudal aspect of the limb, running through the '''carpal canal''' to the metacarpus. The SDFT and DDFT run within a synovial structure termed the '''carpal sheath'''.
Just proximal to the metacarpophalangeal joint, the SDFT forms a ring-like structure which wraps around the DDFT. This structure is known as the '''manica flexoria'''.
From the distal metacarpus to the level of the middle phalanx, the SDFT and DDFT are enclosed by another synovial structure, the '''digital sheath'''.
The SDFT divides into two branches at the distal end of the proximal phalanx. The branches insert on the lateral and medial eminences of the middle phalanx, a minority of fibres also insert on the lateral aspect of the proximal phalanx.
'''Deep Digital Flexor Tendon (SDFT)'''
*'''Origin''': Deep digital flexor muscle on the medial humeral epicondyle, radius and ulna
*'''Insertion''': Distal phalanx
*'''Action''': Flexes the distal phalanx
The deep digital flexor tendon arises as three bellies from its origin on the medial humeral epicondyle, fusing to form a common tendon just proximal to the carpus on the caudal aspect of the limb. The single tendon passes distally, enclosed in the '''carpal sheath''', through the '''carpal canal'''. In the mid-metacarpal region, the tendon is enforced by an accessory ligament ('''inferior check ligament'''). At the metacarpophalangeal (fetlock) joint, the DDFT passes though the '''manica flexoria''' and over the sesamoid groove. In the mid –region of the proximal phalanx, the DDFT runs between the branches of the SDFT and over the flexor cortex of the distal sessamoid ('''navicular''') bone to insert on the flexor cortex of the distal phalanx.
The '''navicular bursa''' is the space formed between the DDFT and the distal sesamoid ('''navicular''') bone, which is filled with synovial fluid. It extends beyond the borders of the distal sesamoid bone proximally, distally and laterally.
The distal parts of the superficial and deep digital flexor tendons are supported by three annular ligaments:
*Palmar annular ligament
*Proximal digital annular ligament
*Distal digital annular ligament
'''Suspensory Ligament (SL)'''
*'''Origin''': Proximal region of third metacarpal (cannon bone) and distal row of carpal bones
*'''Insertion''': Proximal sesamoids, joins common digital extensor tendon
*'''Action''': Prevents fetlock hyperextension and limits palmar flexion
The suspensory ligament (middle interosseous muscle) is an entirely tendinous structure. The SL originates on the proximal aspect of the third metacarpal (cannon) and distal carpal bones. It lies within the groove between the second and fourth metacarpal bones (splint bones), deep to the SDFT and DDFT. Running distally, it bifurcates into two extensor branches which insert on the proximal sesamoid bones. Each branch extends laterally and medially, either side of the metacarpophalangeal (feltlock) joint, to join the common digital extensor tendon. The major function of the SL is as part of the '''suspensory apparatus'''. It provides support to the fetlock by preventing hyperextension and also limits palmar flexion.
==Pelvic Limb==
==Pelvic Limb==
===Extensors===
===Extensors===
===Flexors===
===Flexors===
==References==
==References==