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Chapter 7. THORACIC AND PELVIC LIMBS ( BOVINE )

7.1 NERVES

The distribution of nerves to muscles is very much the same as in horse and dog.


 7.2 DENSITIZING THE DIGITS OF THORACIC LIMB

The digital nerves are from the radial, median, and ulnar nerves. The radial nerve supplies the dorsal nerves except the lateral dorsal nerve. The ulnar nerve supplies the lateral dorsal nerve, and with the median, the lateral palmar nerve. The median nerve supplies the palmar nerves. Only two alternative sites for desensitizing the digits will be mentioned here. They are:
(a) in the region of the metacarpophalangeal joint; (b) at the junction of proximal and middle thirds of the metacarpus. In each, injection at four points is necessary.
7.2.1 (a) In the region of the metacarpophalangeal joint:
- 1.1/2-1 cm in front of medial accessory digit and subcutaneous (medial dorsal nerve and medial palmar nerve);
- 2.1/2-1 cm in front of lateral accessory digit and
- 3. dorsal midline, immediately below the joint and 1 cm deep (axial dorsal nerves);
- 4. palmar midline, immediately below level of accessory digits and 2 cm deep: large artery and vein here: (axial palmar nerves).
 
Synonyms of the above nerves:
Lateral dorsal nerve - abaxial dorsal nerve of digit IV.
Lateral palmar nerve - abaxial palmar nerve of digit IV.
Medial dorsal nerve - abaxial dorsal nerve of digit III.
Medial palmar nerve - abaxial palmar nerve of digit III.
 
(b) 7.2.2 At the junction of proximal and middle thirds of the metacarpus:
- 1. on the medial border of the deep flexor tendon and 2 cm deep. Large artery and vein here: (median nerve);
- 2. on the lateral border of the deep flexor tendon and 1 cm deep: (palmar branch of ulnar nerve);
- 3. 1 1/2 cm in front of (2) and subcutaneous: (dorsal branch of ulnar nerve);
- 4. on the dorsomedial aspect 1-2 cm medial to the medial extensor tendon and subcutaneous: (radial nerve).
 

7.3 DESENSITIZING THE DIGITS OF THE PELVIC LIMB


The nerves of the digits are from the peroneal and tibial nerves, both of these being branches of the sciatic nerve.
The peroneal (superficial and deep branches) supplies the dorsal nerves. The tibial nerve supplies the plantar nerves.
Only two alternative sites for desensitizing the digits will be mentioned here. They are:
(a) in the region of the metatarsophalangeal joint;
(b) at the junction of proximal and middle thirds of the metatarsus.
In (a) injection at four points is necessary;
 
(a) 7.3.1In the region of the metatarsophalageal joint:
 
1. 1/2-1 cm in front of medial accessory digit and subcutaneous (medial dorsal nerve and medial plantar nerve);
2. 1/2-1 cm in front of lateral accessory digit and subcutaneous (lateral dorsal nerve and lateral plantar nerve);
3. dorsal midline, immediately below the joint and 1 cm deep: large artery and vein here: (axial dorsal nerves);
4. plantar midline, immediately below the level of accessory digits and 2 cm deep (axial plantar nerves).
 
Synonyms of the above nerves:
Lateral dorsal nerve - abaxial dorsal nerve of digit IV.
Lateral plantar nerve - abaxial plantar nerve of digit IV.
Medial dorsal nerve - abaxial dorsal nerve of digit III.
Medial plantar nerve - abaxial plantar nerve of digit III.
 
(b) at five points.
 
(b)7.3.2 At the junction of proximal and middle thirds of the metatarsus:
- 1. on the medial border of the deep flexor tendon, and 1 cm deep (medial plantar nerve);
- 2. on the lateral border of the deep flexor tendon, and 1 cm deep (lateral plantar nerve);
- 3&4. on the dorsolateral aspect on the lateral extensor tendon where the two branches of the superficial peroneal nerve lie one on either side of the dorsal common digital vein, subcutaneously;
- 5. almost on dorsal midline, 1 1/2 cm deep where the two branches of the deep peroneal nerve lie one on either side of the artery in the dorsal groove of the metatarsus which is slightly lateral to midline.

 


7.4 SUPERFICIAL VEINS OF THORACIC LIMB

 

Cephalic vein: drains the palmar aspect of the manus. It ascends outside carpal groove on superficial aspect of carpus, crosses medial border of radius, receives accessory cephalic vein, and ascends on cranial aspect of forearm. Above elbow, it ascends between brachiocephalic and superficial pectoral muscles, and enters terminal part of jugular.
 
Accessory cephalic: which joins it on middle forearm, is large and arrives from the dorsomedial aspect of manus.
 
7.4 SUPERFICIAL VEINS OF PELVIC LIMB
7.4.1 Lateral saphenous vein: arises above the tarsal joint from dorsal and plantar tributaries. The dorsal drains from the dorsolateral aspect of metatarsus and tarsus to reach the saphenous in the space between common calcanean tendon and deep digital flexor. At this point, the saphenous receives its plantar tributary. The lateral saphenous vein then ascends at first on the craniolateral aspect of calcanean tendon, then inclines caudally and disappears between biceps and semitendinosus muscles to join femoral vein.
 
7.4.2 Amputation of a digit:
Is more frequently performed in the pelvic limb since the incidence of infections is higher in pelvic digits. The most common level at which amputation is performed is at the distal extremity of PI.
The largest artery encountered during amputation of a pelvic digit is (axial) proper digital artery. The two axial proper digital arteries arise, just proximal to the level of the proximal interphalangeal joints, by the bifurcation of the dorsal common digital artery. This latter artery is situated on the dorsal aspect of the metatarsophalangeal joint: on passing over the joint, it runs in a plantar direction between the digits to divide as described above. Just before dividing, the large dorsal common digital artery receives the much smaller plantar common digital artery. There are medial and lateral (abaxial) digital arteries. Digital veins are satellite to the arteries but, generally speaking, they tend to be more superficially situated than the arteries.
The same general remarks pertain to the vessels of the thoracic digits, with one notable difference: the axial proper digital arteries are supplied mainly by the palmar common digital artery which receives the much smaller dorsal common digital artery.
If amputation is performed at the level of distal extremity of PI, the tendons which will be cut are those of deep and superficial digital flexor, and long and proper digital extensor: (Deep digital flexor to PIII, long digital extensor to PIII) (Superficial digital flexor to PII, proper digital extensor to PII).
The ligaments which will be cut may be selected from the following mention of digital ligaments in general: There are ligaments reinforcing proximal and distal interphalangeal joints which are additional to the intrinsic ligaments of these joints and whose function is mainly to prevent splaying of the digits. The most important one performing this function is the distal interdigital ligaments (Cruciate ligament). The tension in this ligament can be palpated when the animal puts weight on the limb: just as the hoof contacts the ground the tension can be felt in the plantar part of the interdigital space immediately above the level of the hoof. It is a cruciform ligament, i.e., it consists of two parts which cross in the interdigital space and at that point the fibers of the two parts mingle. Each part has an attachment to the abaxial eminence of PII: from this point, it winds around the tendon of digital flexor and goes then to the distal sesamoid of the other digit. . This is not the whole story, however. In addition to attaching to the axial aspect of the distal sesamoid, some fibers spread around the deep flexor tendon and also the digital cushion to reach the abaxial aspect of the sesamoid and PIII. This fact has functional, pathological, and clinical significance. It means that each time the animal places the hoof on the ground, the tension in the fibers will have a sort of pumping effect on the bursa of the distal sesamoid. If this bursa is the site of suppurative process, the infection will tend to be forced further up the digit by the pumping action.
 
7.4.3 Intrinsic ligaments of the joints in the distal region:
Distal interphalangeal joints (Pedal or coffin joints):-
Each joint has a separate joint capsule and each joint has collateral ligaments, axial and abaxial (the axial being specially strong). Then there are ligaments associated with the distal sesamoid of each joint. In each case these are:
Distal ligament of the distal sesamoid (to PIII) " Distal navicular ligament."
Collateral ligaments of the distal sesamoid (from PII)
If the ligaments of this joint are compared with the ligaments of the corresponding joint of the horse, it will be found that there is a great similarity.
 
7.4.4Proximal interphalangeal joints (Pastern joint )
Each joint has a separate joint capsule and each joint has collateral ligaments, axial and abaxial (the axial being especially strong). In addition, each joint has palmar ligaments. So, again, a close similarity to the corresponding joint of the horse will be observed.
 
7.4.5 Metacarpophalangeal joint and metatarsophalangeal joints ( Fetlock joint ).
Again, there are great similarities with the corresponding joint of the horse. For a start, however, a fundamental realization should be made about the skeletal duplication which occurs in the bovine species. In this species, although McIII and IV are fused (as Mt III and IV are fused), the fused bone has, so to speak, a duplicated distal articular surface so that it can articulate with two PI's. And, of course, there are four proximal sesamoids instead of two.
The function of the interosseus in the bovine species is very similar to that of equine because the attachments are practically the same. There is, however, little to be said about the difference in structure. In both bovine and equine species, the interosseus is a modified muscle, compared with the canine species in which the corresponding structures (there being four in each paw) are proper muscles (mm. interossei). The modification in the large animals takes the form of replacement of muscle tissue by fibrous tissue (equine interosseus is a purely fibrous structure in the adult, whereas the bovine interosseus possesses a minimal amount of muscle fibers throughout life. The functional implication of this is obvious.) The bovine interosseus attaches to the proximal sesamoids just like the equine interosseus does, but divides into four branches (one for each sesamoid) with additional abaxial and axial branches which incline dorsally to join up with proper extensor tendons.
 
7.4.6 The sesamoidean ligaments, i.e., the ligaments which attach the proximal sesamoids to PI, are the same as those of the horse except that there is duplication, and absence of any which reach down to PII (i.e, no superficial sesamoidean).
The synovial structures in the region of this joint are essentially very similar to those of the equine ones.
As in the equine species, there is a single joint capsule with a pouch which, if distended, will appear between metacarpus/metatarsus and interosseus and which can be confused (again as in equine) with distention of the digital synovial sheath; this latter distention being situated between interosseus and flexor tendons. The digital synovial sheath is disposed as in equine except that it is duplicated: the two sheaths are in contact proximally, i.e., just above the level of the joint, but they do not usually communicate with each other.
7.4.7 The suspensory ability of bovine limbs: is between that of equine and that of canine limbs. Bovine limbs are less mechanically oriented (i.e., having more muscle involvement) than equine but are more mechanically oriented (i.e., having more fibrous involvement) that canine. In equine limbs, there are fibrous structures which have been developed specifically to reduce muscle fatigue. In bovine limbs, there are fewer such fibrous structures and those that are present are more in the order of compensatory devices. In canine limbs, muscle involvement is at its greatest. The consequence of the above factors is that while canine sp. (like human sp.) never stands when it can sit down or lie down, bovine sp. can stand for fairly long periods, and equine can stand for very long periods at a time.

 


7.5 THE DISTAL DIGITAL REGION OR HOOF REGION

The incidence of affections in this part of the limb is high. The region comprises the hoof and contents of hoof. The anatomy of the region has many similarities to that of equine sp. Duplication of the hoof in bovine sp. involves, among other considerations, the acknowledgement of an abaxial and an axial aspect of the wall of the hoof. In addition, however, there are some fundamental and important differences, not only of the hoof but also of contents of hoof. In brief, although in both species, there is a torus ungulae, the apex of this in bovine sp. extends on to the ground surface of the hoof and merges with the sole part of the hoof: (in equine sp., this apical part is so highly modified as to deserve a special designation which is cuneus ungulae. In bovine sp., there are no ungual cartilages, and there is a digital cushion similar to that of equine but less well developed.
It is a useful exercise to speculate on the reasons for the differences mentioned in the above paragraph: these differences are associated with differences in the design of what may be called the "anticoncussion structures."

 


7.6 CLINICAL CONSIDERATIONS:

The following are some clinical considerations
 
Nerve paralyses;
 
Nerve blocks;
 
Sites of bursitis and tenosynovitis;
 
Sites of joint puncture (arthrocentesis);
 
Sites of joint capsule distensions ;
 
Sites of pulse;
 
Common affections and surgery of hoof and contents of hoof;
 
Palpable and non-palpable lymph nodes;
 
Course of largest subcutaneous veins;
 
Cutaneous innervation
 
Sites of tendon or muscle rupture;
 
Position of growth plates
 
 
 
 
nerve block sites, thoracic limb
 
 
 
nerve block sites, pelvic limb
lumber and sacral dermatomes