Equine Forelimb Flashcards
Why does the forelimb carry more weight than hindlimb
- forelimb touches the ground first
- bears weight of head, thorax, and neck
List 6 joints of forelimb
1) shoulder
2) elbow
3) carpus (3)
4) fetlock
5) pastern
6) coffin
Shoulder joint articulation…
Between scapula and humerus
Elbow joint articulation…
Humerus and radius and ulna
List the 3 carpus joints
- radiocarpal
- intercarpal
- carpometacarpal
Articulation of radiocarpal joint
Radius and first row of carpal bones
Articulation of intercarpal joint
Between 1st and 2nd rows of carpal bones
Articulation of carpometacarpal joint
Second row of carpal bones and the 2nd, 3rd, and 4th metacarpal bones ( medial splint bone, cannon bone, lateral splint bone)
Articulation of fetlock joint
Distal end of cannon bone (3rd metacarpal), proximal sesamoid bones, and first phalanx
Articulation of pastern joint
1st and 2nd phalanges
Articulation of coffin joint
2nd phalanx, distal sesamoid bone, and 3rd phalanx
Olecranon bursa
- function to reduce friction
- clin sig: capped elbow (calcification and inflammation of bursa)
Muscles on lateral side of scapula
- supraspinatus m.
- infraspinatus m.
Muscle(s) on medial side of scapula
- subscapularis m.
Suprascapular n. Location and clin sig
- under skin, between supraspinatus m. and infraspinatus m.
- sweeney shoulder
Clinical signs of sweeney shoulder
Lameness, scapular muscle atrophy, prominent scapular spine
Bicipital bursa
- location: between tendon of origin of biceps muscle and humerus head
- function: prevents overflexion of shoulder; part of passive stay mechanism
Passive stay mechanism
Allows horse to stand for prolonged periods of time without muscle fatigue
- ligaments and tendons take over weight distribution b/c they fatigue slower
Lateral surface muscles of radius
- extensor carpi radialis m.
- extensor carpi obliquus m.
- common digital extensor m.
- lateral digital extensor m.
(All the EXTENSOR MUSCLES)
Muscles on latero-caudal side of radius
- Lacertus Fibrosus
- flexor carpi radialis m.
- flexor carpi ulnaris m.
- deep digital flexor m.
- superficial digital flexor m.
Significance of muscles on the medial surface of radius
Non-existent
Periosteal stripping
- treats: angular limb deformities
- how: creating an inverted T-shaped incision on the periosteum to allow bone on that side to grow faster
List the 3 procedures used to treat angular limb deformities
- periosteal stripping (encourages growth)
- Transphyseal screw placement ( delays bone growth- one screw)
- Transphyseal bridging (delays bone growth- 2 screws)
Two types of angular limb deformities
- Valgus ( “knock-kneed”; medial side grows faster)
- Varus (“bowlegged”; lateral side grows faster)
Angular limb deformities usually affect________
Foals
Extensor carpi radialis tendon and common digital extensor tendon
Pass over carpus
Extensor carpi radialis m. tendon
- insertion: carpometacarpal joint capsule
- landmark for carpus joint access
How to access carpus joints
Insert needle on either side of ECR tendon
Lacertus fibrosus and tendon of ECR
- Prevent carpus joint over extension
- part of passive stay apparatus ( ECR tendon and lacertus fibrosus and flat surface of carpus joints help mech.)
Common digital extensor tendon
- only tendon to reach distal end of forelimb dorsally
- extends digit
- rupture= overflexion
- insertion: extensor process of 3rd phalanx
- landmark for accessing coffin joint
How to access coffin joint
- insert needle on either side of extensor process of 3rd phalanx
- used for arthrocentesis, arthroscopy, joint anesthesia, joint block, and joint injections
Extensor process of 3rd phalanx
- site where CDE tendon is inserted
- landmark for coffin joint access
- site for pyramid disease
Pyramid disease
- calcification of extensor process of 3rd phalanx
- due to chronic trauma and injury
Tendons of Superficial digital flexor m. and Deep digital flexor m.
- insertion: palmar surface of phalanges 1 and 2 (SDF) and phalanx 3 (DDF)
- function: flex digit
- clin sig: club foot
Club foot
- continuous flexion of SDF and DDF tendons
- treatment: sever 1 or 2 ligaments that originate from both tendons
Proximal check ligament
- origin: SDF tendon
- insertion: radius
- can be severed to treat clubfoot
Distal check ligament
- origin: DDF tendon
- insertion: carpus
- can be severed to treat clubfoot
Forelimb has ___ check ligaments and the hindlimb has ____ check ligaments
2; 1 (distal only)
T or F: radiocarpal and intercarpal joints can be accessed individually and have large joint spaces
True
How do you access the carpometacerpal joint
By injecting the intercarpal joint
Extensor carpi radialis m. and common digital extensor m.
- cover dorsal aspect of carpus
Radial and 3rd carpal bones
- most stress on carpal joints occur
- Osteochondrosis dissecans, slab fractures, chip fractures, and bone cysts common medially and high
Splint bones
2nd and 4th metacarpal bones
Cannon bone
3rd metacarpal bone
Metacarpal region
- CDE tendon covers area dorsally
- SDF, DDF, and Suspensory ligament cover ventral area
- predisposed to: tendonitis, periositits (bucked shins), splint and cannon bone fractures, ruptured tendons, contracted tendons
Suspensory ligament
- splits into medial and lateral branches at level of fetlock joint
- changes direction from ventral/caudal surface of cannon bone to dorsal surface of 1st phalanx
- unites with CDE tendon on dorsal surface of 1st phalanx
Best diagnostic technique for tendon injuries
Ultrasound
Bucked shins
- inflammation of periosteum of 3rd metacarpal bone
- when cannon bone is thicker and denser at the front of bone rather than sides or back
Check ligament of SDF/DDF desmotomies
Treatment for tendon injuries
Landmark to access fetlock for arthrocentesis or arthroscopy
Between 3rd metacarpal bone, distal end of 4th metacarpal bone, and lateral branch of suspensory lig?
