Budras_Анатомия лошади

aSupraspinatus

bDeltoideus, resected

cInfraspinatus

dTeres minor

Triceps brachii:

eLong head

fLateral head, resected

gMedial head

hBrachialis

iBiceps brachii

jFlexor carpi radialis, resected

kExtensor carpi radialis

lSupf. digital flexor

mCommon digital extensor (humeral head)

nCommon digital extensor (radial head)

oDeep digital flexor

pLat. digital flexor

qUlnaris lateralis

rFlexor carpi ulnaris, resected

sExtensor carpi obliquus

(Medial view)

Chapter 3: Pelvic Limb

11. The Skeleton of the Pelvic Limb

2The skeleton of the pelvic limb actually includes the bones of the

pelvic girdle: ilium, pubis, and ischium, known together as the hip bone (os coxae). For didactic and applied-clinical reasons the hip bone, in fact the entire bony pelvis, is considered with the pelvic organs.

3a) The FEMUR presents on its head (1) a relatively large, triangular fovea (2). The apex of the fovea lies near the center of the femoral head and its base is close to the medial border of the femoral head.

The fovea, devoid of articular cartilage, gives attachment in the vicinity of its apex to the ligament of the head of the femur and, closer to its base, to the accessory ligament that arises from the prepubic tendon with most of its fibers originating from the insertion tendon of the rectus abdominis. The neck of the femur (3) is no real constriction in the horse; it is continuous laterally with the greater

4''

(Caudolateral view)

4

1

2

5

3

6

7

Clinical and Functional Anatomy p. 130–132

face are further divided by less distinct transverse ridges into large gliding and small resting surfaces; the resting surface of the trochlea is proximal to the gliding surface, that of the patella is distal to it. When both resting surfaces are in contact, the patella “rests” on the proximal end of the trochlea as is the case when the standing horse is bearing weight equally on both hindlimbs.

half-way down the tibia. The distal end of the fibula is represented by the lateral malleolus (35) that has been incorporated in the tibia.

trochanter (4) which is divided into a cranial (4') and a more salient caudal (4'') part. The caudal part extends considerably above the head of the femur, but more ventrally contributes also to the lateral border of the trochanteric fossa (5). The medial border of the fossa is formed by the lesser trochanter (6). The prominent third trochanter (7) projects from the lateral border of the femur at the junction of its proximal and middle thirds. The supracondylar fossa (13) is on the caudal surface of the bone at the junction of middle and distal thirds where it provides origin for the supf. digital flexor. From the fossa's raised lateral edge, known as the lateral supracondylar tuberosity, arises the lateral head of the gastrocnemius. The medial (14) and lateral (17) condyles at the distal end of the femur are separated by a roomy intercondylar fossa (20). Both

4condyles extend cranially to the trochlea (21) whose medial ridge (21') is markedly larger than the lateral ridge and drawn out proximally to provide a tubercle which plays a critical role in the locking mechanism of the stifle joint (see p. 24). The trochlea presents

5an extensive gliding surface for articulation with the patella (69). The latter, roughly triangular, presents a base (69') proximally and an apex (69'') distally. The medial border is drawn out by the patellar fibrocartilage (69''''). The articular surface of the patella (69''''') is divided by a sagittal ridge that occupies the groove between the two ridges of the trochlea. Both patellar and trochlear articular sur-

69'

(Caudal view)

69''''

69'''''

69''

43

42

37 44

45 46

(Medioplantar view)

d) The METATARSAL BONES, PHALANGES AND SESAMOID BONES are

similar to corresponding bones in the forelimb (see p. 4). Mt3 has a round cross section, while that of Mc3 is a lateromedially oriented oval.

Pelvic Limb

Femur

Head (1)

Fovea of femoral head (2) Neck (3)

Greater trochanter (4) Cranial part (4') Caudal part (4'') Trochanteric fossa (5)

Lesser trochanter (6) Third trochanter (7) Body of femur (8)

Rough surface (9)

Lat. border of rough surface (10) Med. border of rough surface (11)

Popliteal surface (12)

Lat. supracondylar tuberosity (fossa) (13) Medial condyle (14)

Medial epicondyle (16) Lateral condyle (17)

Lateral epicondyle (19) Intercondylar fossa (20) Trochlea (21)

Popliteal line (27')

Body of tibia (28)

Subcutaneous surface (28')

Tibial tuberosity (29)

Cranial border (29')

Cochlea (30)

Medial malleolus (31)

Fibula

Head (32)

Articular surface (33)

Body of fibula (34)

Lateral malleolus (35)

Interosseous space (36)

Tarsal bones

Talus (37)

Body of talus (38)

Trochlea (39)

Head (41)

Calcaneus (42)

Calcanean tuber (43)

Sustentaculum tali (44)

Central tarsal bone (Tc – 45)

Tarsal bone 1+2, 3, 4 (46)

Metatarsal bones II–IV

Base (47)

Body (48)

Head (49)

Digital bones

Proximal phalanx (50)

Middle phalanx (51)

Base (52)

Flexor tuberosity (53)

Body (54)

Head (55)

Distal phalanx (56)

Articular surface (57)

Extensor process (58)

Parietal groove (59)

Plantar process (59')

Sesamoid bones

Proximal sesamoid bones (66)

Distal (navicular) sesamoid bone (67)

Patella (69)

Base (69')

Apex (69'')

Cartilage process (69''')

Patellar fibrocartilage (69'''')

Articular surface (69''''')

4''

4' 4

5

7

(Caudolateral view)

9

10

11

8

13

12

20

17

14

26

32

36

34

27'

28

T III

49

66 66

53

57

67

59'

The two Figures on the opposite page show the structures mentioned in the account below to best advantage. The following steps would reproduce the dissection upon which the two Figures were based.

The limb is skinned to midmetatarsus, preserving the subcutaneous veins and the larger nerves (see p. 21). Dorsolaterally on the croup, the large gluteus medius (3) is transected at the level of the coxal tuber, and again where it inserts on the greater trochanter, so that the muscle between these cuts can be removed. The gluteus accessorius (9), deep to it and covered by a glistening aponeurosis, remains in place. At the latter's caudal border, the gluteus profundus (6) comes into view. The gluteus superficialis (11) and tensor fasciae latae (20) are detached at their origin (coxal tuber) and termination. Most of the biceps femoris (22) is removed, leaving in place its vertebral and pelvic origins, and its termination on the crural fascia, and its tarsal tendon. The lateral head of the gastrocnemius (26) is detached from the femur to expose the supf. digital flexor (31). The gracilis (21), on the medial surface is fenestrated.

1a) MEDIAL SIDE OF THE THIGH. The obturator and femoral nerves innervate the muscles in this region.

The obturator nerve (5) courses along the medial surface to the shaft of the ilium, exits from the pelvic cavity through the obturator foramen, and sends branches to the muscles described below.

The external obturator muscle arises from the ventral surface of the pelvic floor in the vicinity of the obturator foramen and ends together with the gemelli, quadratus femoris, and the internal obturator in the trochanteric fossa. The pectineus (and long adductor; 14) takes origin from the contralateral iliopubic eminence so that its tendon of origin crosses the median plane. The tendon of origin, and that of the pectineus of the other side, thus form the bulk of the prepubic tendon. The spindle-shaped belly of the pectineus ends at the middle of the medial border of the femur. The adductor (magnus et brevis; 19) is a large fleshy muscle; it arises from pelvic symphysis and symphysial tendon. It ends on the caudal surface and the medial epicondyle of the femur. The gracilis (21) originates from the pelvic symphysis and the symphysial tendon. It ends largely on the crural fascia.

The femoral nerve (12) leaves the abdominal cavity together with the sartorius muscle, gives off the saphenous nerve (25) (see further on) and innervates the sartorius, the quadriceps, and (with a sensory branch) also the stifle joint.

The sartorius (10) arises from the iliac fascia covering the iliopsoas, exits from the abdominal cavity by passing caudal to the inguinal ligament, and ends on the medial aspect of the stifle.

The rectus femoris of the quadriceps (15) takes origin from the body of the ilium, while vastus lateralis, intermedius, and medialis come from the upper end of the femur. The insertion tendon partially encloses the patella and terminates via the intermediate patellar ligament (15) on the tibial tuberosity.

The femoral triangle (16) is bounded cranially by the sartorius and caudally by the gracilis and pectineus; its medial wall is the external abdominal oblique aponeurosis. The apex of the triangle points ventrally; the vascular lacuna forms the (dorsal) base. The triangle contains the femoral vessels (18), the saphenous nerve, and the deep inguinal lymph nodes (B).

b) LATERAL SIDE OF THE THIGH AND CROUP. The innervation of the

muscles in this region comes from the cranial and caudal gluteal, the sciatic, and the tibial nerves.

2The cranial gluteal nerve (8) supplies the tensor fasciae latae (20) and the glutei: gluteus profundus (6), accessorius (9), medius (3), and superficialis (11). These muscles arise variously from the coxal tuber, the gluteal surface of the ilium, and from the gluteal fascia.

The gluteus accessorius is considered to be a deep part of the gluteus medius. The gluteus superficialis is partly fused with the tensor fasciae latae; both arise from the coxal tuber but also from the gluteal fascia.

The caudal gluteal nerve (2) supplies the vertebral heads of biceps, semitendinosus, and semimembranosus (the hamstring muscles).

(Lateral view)

22

49

A

r

r

u

(See p. 65)

The skin over the dorsal and lateral regions of the croup is innervated by cranial, middle, and caudal clunial nerves that arise from the lumbar, sacral, and caudal spinal nerves, respectively; one of them is recognized as the caudal cutaneous femoral nerve (17). The craniolateral surface of the thigh receives cutaneous innervation from the ventral branches of the first (L1; 2) and second (L2; 3) lumbar nerves. The craniomedial surface is supplied by the lateral cutaneous femoral nerve (6), the medial surface by the genitofemoral nerve (5), and the caudal surface by the caudal cutaneous femoral nerve (17).

The skin of the leg (crus) is supplied medially by the saphenous nerve (9); craniolaterally by the common peroneal nerve, especially the lateral cutaneous sural nerve (21); and caudomedially by the tibial nerve, especially its caudal cutaneous sural nerve (23).

The medial surface of metatarsus and digit receives its skin innervation from the saphenous nerve and farther distally by a mixture of tibial and peroneal nerve branches. The dorsal surface is supplied by the dorsal metatarsal nerves (15) which are branches of the deep peroneal nerve, and the plantar surface is supplied by the medial and lateral plantar nerves (26) and their continuations, the medial and lateral digital nerves (27).

Cutaneous Nerves of the Pelvic Limb

Blood supply to, and return from, the pelvic limb flows predominantly through the external iliac vessels, though the internal iliac vessels are also involved.

The internal iliac vessels (1) release the cranial (18) and caudal (16) 1 gluteal vessels to the croup and thigh. The cranial gluteal artery gives off the obturator artery, while the satellite obturator vein is a branch of the external iliac vein.

As the external iliac vessels (4) enter the thigh by passing caudal to the inguinal ligament, they become the femoral vessels (8). These at once give rise to the deep femoral vessels (19) which in turn release the pudendoepigastric trunks (19'). As the femoral vessels traverse the femoral triangle they give off the lateral circumflex femoral vessels (7) that enter the quadriceps between rectus femoris and vastus medialis, and the saphenous vessels (9) of which the vein is very much larger than the artery; these accompany the like-named nerve and in the proximal third of the leg divide into cranial (10) and caudal (11) branches. The cranial branch of the vein passes the tarsus dorsomedially to become the dorsal common digital vein II (14) in the metatarsus. This crosses the large metatarsal bone obliquely and unites with the medial plantar vein (see p. 22). The caudal branches of the medial saphenous vein and artery pass distally in the groove cranial to the common calcanean tendon. The vein anastomoses proximal to the hock with the caudal tibial vein (25) and with the lateral saphenous vein (23) and passes the hock plantaromedially where it divides into medial and lateral plantar veins (26). The saphenous artery anastomoses with the caudal tibial artery (25; see further on) and gives rise to the medial and lateral plantar arteries (26).

In the distal third of the thigh the femoral vessels release the descending artery and vein of the stifle (20) and other vessels to that joint. Some of the latter arise from the popliteal vessels (24; see further on) that continue the femoral vessels at this level. The last branches of the femoral artery and vein are the caudal femoral vessels (22). The large caudal femoral vein releases the lateral saphenous vein (23) which follows the caudal border of the gastrocnemius distally to anastomose proximal to the hock with the caudal branch (11) of the medial saphenous vein and with the caudal tibial vein (25; see above). Opposite the head of the fibula, the popliteal vessels bifurcate to give rise to the cranial (12) and the smaller caudal (25) tibial vessels. The caudal tibial vessels descend caudal to the tibia. The cranial tibial vessels, however, pass cranially between tibia and fibula, follow the tibia craniolaterally, and at the hock become the short dorsal pedal vessels (14). The continuation of the pedal artery, the dorsal metatarsal artery, is the largest artery in the metatarsus. It passes over the lateral surface of the cannon bone, then between this bone and the distal end of the lateral splint bone to the plantar surface where it receives the thin plantar metatarsal arteries that descend on the plantar aspect of the metatarsal bones.

c) LYMPHATIC STRUCTURES

Numerous lymph vessels leave the hoof and, similar to the forelimb (see p. 8), unite proximal to the fetlock joint to form a small number of larger lymphatics. Most of these lie on the medial aspect of the metatarsus between the flexor tendons; they ascend medial to hock and leg until they reach the popliteal lymph nodes (see p. 19.A). These lie caudal and proximal to the stifle between biceps and semitendinosus. From here the lymph travels to the deep inguinal nodes (see p. 19.B) which occupy the femoral triangle, and finally to the medial iliac nodes (see p. 19.C). The deep inguinal nodes receive lymph also from the medial surface of leg and thigh that does not pass through the popliteal nodes. Croup and cranial thigh drain to the subiliac nodes (see p. 19.D) which lie on the cranial border of the thigh between coxal tuber and patella. From here the lymph travels first to the lateral and then to the medial iliac nodes. A portion of the lymph from the medial aspect of the thigh passes to the supf. inguinal lymph nodes.

9Saphenous artery and nerve, and medial saphenous vein

10Cranial branches of 9

11Caudal branches of 9

k

h'

21 Lat. cutaneous sural nerve (peroneal)

22 Caudal femoral vessels

23 Lat. saphenous vein and caudal cutaneous sural nerve (tibial)

24 Popliteal vessels

25 Caudal tibial vessels

15 Medial and lateral dorsal metatarsal nerves (peroneal)

27 Medial and lateral plantar vessels and nerves

aDeep circumflex iliac vessels

bUmbilical artery

cInternal pudendal vessels

dPudendal nerve

eObturator vessels and nerve

fFemoral nerve

gMedial circumflex femoral vessels

hCommon peroneal nerve

h' Supf. peroneal nerve h'' Deep peroneal nerve

iTibial nerve

jAnastomosis betw. obturator and caudal femoral vessels

m

p

kVessels to the stifle

lMedial dorsal metatarsal vein

mLat. dorsal metatarsal artery

nDeep branch of lat. plantar nerve

oDeep branches of medial plantar vessels

pMedial plantar metatarsal nerve

qMedial digital nerve

rCaudal gluteal nerve

sAccessory ext. pudendal vein Quadriceps femoris

(See p. 19, 22, 23, 81)

1

2

e

i

j

k

Saphenous artery and nerve, and medial saphenous vein

aCranial branches

bCaudal branches

cLat. saphenous vein and caudal cutaneous sural nerve (tibial)

dCaudal tibial vessels

eTibial nerve

fGastrocnemius

gPopliteus

hMed. digital flexor

iSupf. digital flexor

jTibialis caudalis

kLat. digital flexor

lTibialis cranialis

mPeroneus tertius

nLong digital extensor

oLateral digital extensor

7 Dorsal common digital vein II

8 Medial dorsal metatarsal vein and nerve

9 Dorsal metatarsal artery and lateral dorsal metatarsal nerve

10 Medial plantar vessels and nerve

11 Lateral plantar vessels and nerve

12 Communicating branch

13 Medial plantar metatarsal nerve

14 Lateral plantar metatarsal nerve

15 Medial digital vessels and nerve

16 Lateral digital vessels and nerve

17 Dorsal branches of digital nerves

18 Branches to the digital cushion

(See p. 19, 21, 22, 25)

23

1The PASSIVE STAY-APPARATUS prevents collapse of the hindlimb with only a minimum of muscular effort. That is to say, it prevents flexion in stifle and hock joints and overextension in the fetlock and phalangeal joints. These joint movements are opposed by the various components of the stay-apparatus (which include the deep fascia) and by the horse's ability to lock the stifle joint. When horses stand quietly for extended periods they support the hindquarters with only one hindlimb while resting the other (relaxed) on the toe of the hoof with the pelvis tilted slightly toward the “shorter”, nonsupporting limb. The horse itself appears relaxed and comfortable with the three-legged support. (It cannot rest one of the forelimbs, however.)

(Craniomedial view)

patellar ligaments

Medial

Intermediate

Lateral

An important part of the passive stay-apparatus is the so-called

2reciprocal mechanism that links the actions of stifle and hock joints. This is accomplished by the tendinous peroneus tertius muscle and the nearly tendinous supf. digital flexor muscle, both crossing the joint spaces of the two joints. The peroneus tertius arises (by a common tendon with the long digital extensor) from the lateral condyle of the femur and, passing cranial to the tibia, ends by complex attachments on certain tarsal bones and the proximal end of the large metatarsal bone. The supf. digital flexor lies caudal to the tibia and connects the caudal surface of the femur with the calcanean tuber. The schematic representation of the stay-apparatus on the opposite page shows that stifle and hock must move in unison and, if the stifle joint is locked, that the hock joint is als rendered incapable of movement.

The fetlock and phalangeal joints are supported as in the forelimb by the interosseus and the supf. and deep flexor tendons with the fetlock joint slightly overextended in the standing animal. The

3tendinous interosseus arises proximal to the fetlock, attaches on the proximal sesamoid bones, and is functionally continued by the distal sesamoidean ligaments that attach on the plantar surface of the proximal two phalanges. The supf. and deep flexor tendons also attach proximal and distal to the fetlock and lend further support. The tendinous structures are under tension when weight is on the overextended fetlock joint and support the joint by preventing it from overextending further.

There are two differences from the arrangement in the distal part of

4the forelimbs. (1) The accessory (check) ligament of the deep flexor is much thinner and may be absent. (2) The supf. digital flexor tendon has no accessory ligament, but this is compensated for in the hindlimb by its firm attachment on the calcanean tuber: its attachment proximal and distal to the fetlock joint still helps to prevent overextension in this joint when the limb is supporting weight.

By being able to lock the stifle, the horse converts the jointed column of its hindlimb into a weight-bearing pillar. This is accomplished by the very asymmetrical femoral trochlea, the patella, and two of the three patellar ligaments. The medial ridge of the trochlea is larger than the lateral and is prolonged proximally to form a rounded tubercle (see p. 17.21'). The medial patellar ligament connects to the medial border of the patella via the patellar fibrocartilage, while the intermediate patellar ligament attaches directly on the patellar apex. The two ligaments therefore diverge from a common origin on the tibial tuberosity and with patella and its fibrocartilage form a loop that embraces the tubercle on the medial trochlear ridge. When the horse is standing squarely on both hindlimbs the patella rests at the proximal end of the trochlea, without the loop fully embracing the tubercle. Perhaps only the tonus in the muscles attaching on the medial and lateral patellar ligaments (gracilis, sartorius; biceps, tensor fascial latae) keeps the patella in place. When the horse rests one hindlimb on the toe of the hoof, the patella in the supporting limb rotates medially (about 15 degrees) and the fibrocartilage and medial patellar ligament slide farther caudally on the tubercle, fully locking the stifle.

Thus, the locking of this key joint enables the horse to stand with little muscular activity. Some effort must be required, however, because the horse tires after a few minutes and shifts its weight to the other hindlimb.

Distal Phalanx (coffin bone) with ossified Hoof Cartilages

The HOOF AND ITS CONTENTS are popularly known as the foot of the horse, although this structure in no way corresponds to the human foot. The supporting structures enclosed by the hoof include the following: the distal portion of the middle phalanx, the distal phalanx with the insertions of the extensor and flexor tendons, the coffin joint with its capsule and collateral ligaments (see p. 15), the navicular bone and the medial and lateral hoof cartilages. These lie against the concave deep surface of the hoof but project with their dorsal borders above the coronary border of the wall. Several ligaments attach the hoof cartilages to the three phalanges and to the navicular bone. The latter forms part of the plantar (palmar) wall of the coffin joint capsule, articulating with both middle and distal phalanges. It is suspended from the distal end of the proximal phalanx by the collateral navicular ligaments, and distally it is connected by a short but wide distal navicular ligament to the plantar surface of the distal phalanx; the last-named ligament strengthens the coffin joint capsule at his location.

The deep flexor tendon changes direction as it passes over the navicular bone. The navicular bursa between the two structures provides frictionless movement of the tendon over the bearing surface provided by the bone. Navicular bone, bursa, and the tendon are of great clinical importance (see p. 14).