Thoracic Limb 2 Flashcards
In the horse, what are the two insertions of the biceps brachii m.?
Deep: radial tuberosity
Superficial: proximal MC 3
What is the superficial part of the biceps brachii called and what does it blend with?
lacertus fibrosus; blends with epimysium of extensor carpi radialis
In the horse, what is the origin and insertion of the flexor carpi radialis?
O: medial epicondyle of humerus
I: proximal MC bones
In the horse, what are the 2 heads of the flexor carpi ulnaris and where do they insert?
ulnar and humeral; insert on the accessory carpal bone
In the horse, what is the origin and insertion of the superficial digital flexor?
O: medial epicondyle of humerus
I: distal P1, proximal P2 (like the pelvic limb)
What species have check ligaments?
horse only
In the horse, where does the superior/proximal check ligament originate and insert?
O: distal radius
I: tendon of the superficial digital flexor
In the horse, what are the 3 heads of the deep digital flexor and where do they insert?
ulnar, humeral, radial; insert on P3
In the horse, where does the inferior/distal check ligament originate and insert?
O: fascia over the carpal bones
I: tendon of the deep digital flexor
Which check ligament is almost always present in the horse and what is its relative thickness to the other check ligament?
inferior/distal check lig; is THICK compared to the superior/proximal
What is the range of movement of the carpal (knee) joint?
flexion and extension only
What happens in the carpal (knee) joint as the thoracic limb comes under weight?
Shock is transmitted up the limb, reaches the carpal area, carpal bones are able to expand and contract, and the ligaments keep everything together.
What can happen to the carpal region when it comes under excessive force (especially in racehorses, for example)?
Can end up with hyperextension, +/- fractured bones
What ligaments in the carpal region are very robust?
collateral ligaments
How many joint capsules does the carpal region have?
1 (there are individual sacs surrounding each joint, however)
What are the 3 joints of the carpal region?
- Antebrachiocarpal
- Middle carpal
- Carpometacarpal
Which joints of the carpal region communicate with each other?
middle and carpometacarpal
Which joint of the carpal region is on its own/does NOT communicate with other joints?
antebrachiocarpal joint
Where is the antebrachiocarpal joint located?
Carpal region - bt radius and proximal carpal bones
Where is the middle carpal joint located?
Carpal region - bt proximal and distal carpal bones
Where is the carpometacarpal joint located?
Carpal region - bt distal carpal bones and MC bones
How many injections are needed when treating the carpal region for full anesthesia?
2
How many degrees of flexion can you have across the entire carpal region?
135
Which carpal joint has the greatest range of flexion and how many degrees is it?
Antebrachiocarpal joint - 90 degrees
How many degrees of flexion does the middle carpal joint have?
45
Which carpal joint has the least range of flexion and how many degrees is it?
Carpometacarpal joint - it is immotile (0 degrees flexion or extension)
What is the range of movement of the elbow (cubital) joint?
flexion and extension only
What reinforces the restricted range of movement of the cubital joint?
substantial medial and lateral collateral ligaments
How does the radius articulate with the humerus?
When the humerus is engaged with the radius, it is on a flat part of the humerus
Where does the central part of the articular surface between the humerus and radius sit in relation to the collateral ligaments?
cranial to the collateral ligaments
What does the cranial orientation of the articular surface in relation to the collateral ligaments result in at the elbow joint?
A lot of surface tension in the ligaments and makes the joint stable at rest
What type of joint is the horse’s elbow at rest?
“snap” type joint; is stable at rest
How many joint capsules/sacs surroudn the elbow joint?
1 capsule, 1 sac
How many injections are needed in the elbow joint for anesthesia?
1
Where is the intertubercular bursa of the shoulder located?
Deep to the biceps brachii tendon
What is the function of the interbubercular bursa?
It is in place to help dissipate forces on the shoulder
Is the intertubercular bursa a true bursa in large animals?
Yes because it is separate from the joint space (however, it is not a true bursa in the small animal)
T/F: The shoulder joint has true collateral ligaments
False
What supplies medial stabilization to the shoulder joint?
subscapularis m.
What supplies lateral stabilization to the shoulder joint?
infraspinatus m.
What holds the tendon of the biceps brachii into the bicipital groove?
transverse humeral ligament
What is the clinical relevance of the transverse humeral ligament with the tendon of the biceps brachii?
It can become inflamed and cause severe lameness
What is the axillary a. a continuation of?
subclavian a.
What are the 3 branches of the axillary a.?
- Suprascapular a.
- Subscapular a.
- Cranial circumflex humeral a.
Where does the suprascapular a. run?
goes around the cranial scapula
Where does the subscapular a. run?
Bt the teres major and subscapular mm.
What is a branch of the subscapular a. and what does it supply?
thoracodorsal a. –> latissimus dorsi m.
What marks the transition from the axillary to brachial a.?
cranial circumflex humeral a.
What are the branches of the brachial a.?
- Deep brachial a.
- Bicipital a.
- Transverse cubital a.
- Collateral ulnar a.
- Common interosseus a.
Where does the deep brachial a. run?
Caudally to the triceps m.
Where does the bicipital a. run?
Cranially to the flexors of the elbow
Where does the transverse cubital a. run?
Cranially to the elbow
Where does the collateral ulnar a. run?
Caudally to the antebrachium near the ulnar a.
Where does the common interosseous a. run?
Caudally to the distal limb, through the proximal interosseous space
What marks the transition bt the brachial and median a.?
common interosseous a.
What does the median a. supply?
DISTAL LIMB!!!
In the horse, what is the dorsal carpal rete and what does it give off?
dorsal carpal arterial network; gives off dorsal MC aa. II and III
In the horse, where do the dorsal MC aa. II and III run?
Bt the cannon and splint bones (2nd and 4th MC bones) - but can vary bt individuals
What is the primary supply to the distal thoracic limb?
median a.
In the horse, what does the palmar branch of the median a. join and what do they become?
Joins collateral ulnar a. to become the lateral palmar a.
In the horse, what does the deep branch from the lateral palmar a. fuse with and what do they form?
Fuses with the radial a. to become the proximal deep palmar arch.
In the horse, what does the proximal deep palmar arch give off and where are these branches located in relation to the suspensory ligament?
Gives off medial and lateral palmar MC aa. that run deep to the suspensory ligament
In the horse, what marks the transition from median a. to medial palmar a.?
The point at which the radial a. joins the median a.
In the horse, what is the course of the medial palmar a. distally and what does it give rise to?
Moves deep to the digital flexor tendons and gives rise to medial and lateral palmar digital aa.
In the rmt, what is the dorsal MC a. III similar to?
dorsal MT a. III
In the rmt, where does the dorsal MC a. III run?
deep to the digital extensor tendons and lays in a groove made by the fused 3rd and 4th MC bones
In the rmt, what are the 3 dorsal to palmar connections that come from the dorsal MC a. III?
- Proximal perforating branch (@ proximal cannon)
- Distal perforating branch (@ at distal cannon)
- Interdigital a. (bt P1 of digits 3 and 4)
In the rmt, what comes off of the median a. above the hock?
Nothing (does not have a palmar branch like in the horse)
In the rmt, what does the radial a. become just before the hock region?
medial palmar a.
In the rmt, what makes up the proximal deep palmar arch and what does the arch give off?
Made up of deep branches from medial and lateral palmar aa.
Gives off palmar MC aa. II, III, IV
In the rmt, what marks the transition bt the median a. and the palmar common digital a. III?
Branching of the distal deep palmar arch and lateral palmar a. @ fetlock
How does the median a. reinforce the medial palmar a.?
By giving off the distal deep palmar arch.
After the median a. gives off its branches at the fetlock, what do the medial and lateral palmar aa. become?
palmar common digital aa. II (medial) and IV (lateral), and eventually to the palmar proper digital aa.
What forms the brachial plexus?
Ventral branches of spinal nn. from C6-T2
Where does the suprascapular n. run?
Bt supraspinatus and subscapularis mm. along the cranial margin of the scapula
What does the suprascapular n. supply?
Supraspinatus and infraspinatus mm.
What happens if there is injury to the suprascapular n.?
Can have atrophy to the mm. (sweeny), prominent scapular spine, lateral deviation of the shoulder
What is the proximal course of the musculocutaneous n.?
It forms a loop around the axillary n. to join the median n.
What is another name for the axillary loop?
ansa axillaris
What vessel is caudal to the musculocutaneous n.?
brachial a.
What are the 2 branches of the musculocutaneous n.?
Proximal and distal to the biceps brachii and brachialis mm.
What vessel is cranial to the ulnar n.?
axillary a.
What nerve is caudal to the ulnar n.?
radial n. (it is HUGE)
What does the radial n. innervate?
All extensors distal to the shoulder joint
Where does the axillary n. run?
Bt the teres major and subscapularis mm.
What does the axillary n. innervate?
Teres major, teres minor, deltoideus mm.
What does the thoracodorsal n. innervate?
latissimus dorsi m.
T/F: You can often see 2-4 subscapular nn.
True
In the horse, what innervates the suspensory ligament in the pelvic limb?
lateral plantar n.
In the horse, what innervates the suspensory ligament in the thoracic limb?
lateral palmar n.
What is unique about the radial n. and its branches in the horse?
They do NOT extend below the carpus
In the horse, what does the palmar branch of the median n. join and what do these become?
Joins ulnar palmar branch lateral palmar n.
In the horse, what marks the transition from median n. to medial palmar n.?
Palmar branch of the median n.
In the horse, what branch of the lateral palmar n. dives thru the suspensory ligament to give rise to the palmar MC nn?
ulnar part
In the horse, what does the lateral palmar n. become at the fetlock?
lateral palmar digital n.
In the horse, what does the medial palmar n. give off in the mid-cannon region and what does it join?
Gives off a communicating branch that joins with the lateral palmar n. over the SDF tendon.
In the horse, what does the medial palmar n. become at the fetlock?
medial palmar digital n.
In the rmt, what does the medial palmar n. give off in the mid-cannon region and what does it join?
Gives off a communicating branch that joins with the lateral palmar n. over the SDF tendon.
In the rmt, after the communicating branch from the medial palmar n. joins the lateral palmar n., what is given off?
Common digital nn. II, III, IV
If you block the median n., what other nerve is also blocked distally?
Medial palmar n.
If you block the ulnar n., what other nerve is also blocked distally?
Lateral palmar n.
In the rmt, where are regional anesthesia blocks performed in the distal limb?
Proximal part of the 3rd and 4th MC bones
In the rmt, what are the 2 ulnar branches that are given off on the lateral distal limb?
Lateral palmar branch –> palmar surface of the suspensory ligament
Dorsal branch –> dorsal surface of the suspensory ligament
