THE HINDLIMB JOINTS AT THE BROWN BEAR
Spãtaru Mihaela, C. Spãtaru
USAMV Iasi, Faculty of Veterinary Medicine, Aleea M. Sadoveanu nr 8
Keywords: bear, joint, tibia, menisci, flexion
Abstract: The passing from the patrupedal moving to the biped station determines the hindlimb joints
solicitation on the corporal weigh and muscular activity actions. Consequently, the modifications of the articular
structures that are produced, determine the moving in good conditions. So, at the sacro-iliac joint level, facies
auricularis is extended to all sacral vertebras and to the whole dorsal half of the ilium palette, it being
strengthened by short and strong fascicles that consolidate them as a whole. In addition to that, two-three iliolumbaris
fascicle double the ventral sacro-iliac ligament. The ligamentar acetabular fosse displacement facilitates
the prancing and the biped position through the displacing of the weigh center towards the median plan. In
flexion, the medial tibial rotation is produced by the caudal sliding of the lateral menisci. The plantigrad station
determines the thickness and impregnating with cartilage that leads to from the transformation of the tarsometatarsian
joint into an articular complex with a reduced mobility. The missing of the collateral ligaments, an
aspect in correlation with the aspect of the navicular distal articular surface, determines the foot deviation
towards the interior. The lateral moving is limited by the calcanean articular surfaces.
INTRODUCTION
The brown bear (Ursus arctos) is a plantigrad animal with a predominantly patrupedal
movement. The passing from the patruped to the biped station determines the supplementary
solicitation of the hindlegs joints both by the muscles activity and because they support the
whole weight.
MATERIAL AND METHODS
The study was made on two bears killed by hunting. The articulations of the pelvic leg
were processed through the classic anatomical methods that include the dissection, the
identification and preparation of the articular structures and drying and airing preservation.
After the dissections, for exemplifying and interpretation, the results were photographed.
RESULTS AND DISCUTIONS:
The brown bear presents, as the human being, the plantigrad support. On the other
hand it moves the body with the same easiness both in the patruped and biped station (1, 8).
Consequently, by bears, the pelvic joint with the spine is extremely solicited, the coxo-sacral
articular surfaces are extended to the whole dorsal half of the ilium palette and on all the
sacrale vertebras. The articulation is consolidated by the intraarticular ligaments and the
dorsal and ventral sacroiliac ligaments which are extremely short and very strong and at the
same time united with the same periostal fibres (fig. 1, A, B) (7, 8). To the bear, one can see a
bunch formed by two-three ventral ilio-lumbar fascicles with insertion between the ilium
palette and the transversus process of the last lumbar vertebras (fig. 1, B). The sacro-tuberos
ligament is represented by a strong and thick band that, together with its opposite, coordinate
the prancing muscles force (fig 1-A).
The hip joint is particularized by a large mobility, but limited by the muscular mass
(2). The articular capsule is inserred to the base of the femoral head articular circumference
(fig. 2-A, B). The articular surface of the acetabular cavity is more excavated being
interrupted in its centre by a ligamentar fosse that is large and oriented towards to the medial.
In the biped station the body weigh is moved towards the central axis, in this way being better
sustained by the inferior legs.
The femoral head has a hemicylindrical articular surface, having a ligamentar fosse
with a circle aspect. The round ligament is conical in shape, 1 cm length, aspect that allows
the ample abduction and rotation moving of the leg (fig. 1-A). At the same time, the conic
disposition of the round ligament determines the pressure produced through a muscle action
on each segment to the cavity to be uniformly supported by whole articulatory complex,
especially when moving the body up and down in biped station.
The femuro-tibial joint (the principal part of the knee joint), as to the rest of mammals,
presents the main articular surfaces incongruent as an aspect (4, 5). The capsule is large.
Laterally and medially the well represented collateral ligaments are structured (1, 2).
The medial collateral ligament, thicker than the other, is inserred to the ligamentar fosse of
the medial condile of the femur and to the basis of the tibial medial condile. The lateral
collateral ligament is represented by a more reduced ligament that is inserred on the
ligamentar fosse of the lateral condil and proximal extremity of fibula (fig. 3-A, B).
The decussated ligaments are formed by the thicker fascicles. The anterior ligament
has its origin on the tibial central ligamentary fosse and the insertion on the medial faces of
the lateral femoral condil. The caudal fascicle, thicker too, is inserred into the femoral
intercondilar fosse and to the tibial caudal incisure (fig. 3- C).
The articulary menisci have a half moon aspect and relatively thin and are united by a
bunch of fibres. Caudally, as to the rest of mammals, the lateral meniscus has a double
insertion, menisco-tibial and menisco-femural ligaments. The medial meniscus is anterior
inserred by the ligamentar tubercle of the posterior ligament and this is being placed to the
other condile of the tibia. This long insertion limitates its moving. During the flection, the
lateral meniscus moves to the caudal zone, through its sliding on the rounded articulary
surface of the lateral condile of the tibia. Therefore, these aspects allow the tibial rotation
around it axis in report of the femur (fig. 1- A). The articular surfaces of the femoral condiles
are particularized through the disposition of the articular surfaces that are separated into two
plans that are limited by a reduced articular crest: one plan for extension and the other for
flexion. The femuro-patelar articulation is made between the femur throchlea and patellar
cochleea, as usual (2, 3). The throchlea appears as a large notch delimited by a reduced crests.
The tibio-patelar ligament is represented by a thick fascicle inserred on the cranial tuberosity
of the tibia, about 2-3 cm upper by the articular circumference. The femoral condiles present
the femoral sesamoids articular surfaces with about 1, 5-2cm, their articulations having a
reduced but a strong capsule. Sometimes, only lateral presents is described, because the
medial is as a fibro-cartilaginous condensation into the tendon (fig. 1).
The proximal tibio-fibular joint is represented by a plane articular surface both
fibulary and tibialy. The large tibio-fibular space is completed to the 1/3 distal by an
incomplete and thin fibrous blade (3). The distal fibulo-tibial articulation is plane, obliquely
oriented and its surface forms the lateral wall of the cochlea (fig. 4, 5, 6).
The tibio-tarso-mtatarsien joint (the heel joint) has a large capsule that covers the
whole articular complex. Dorsally it has two ligaments thickness that go from the talus dorsal
ligament fosse to the tibia, cuboideum and first cuneiform, central bone and the ligament
fascicles among the tarsian bones (1). From the collateral ligaments we remark the presence
of the fibulo-calcaneen ligament situated laterally, the fibulo-astragalian ligament situated
caudally and the calcaneo-naviculare ligament. The rest of bones are articulated through some
short ligaments (fig. 5, 6). At the plantar level, a long and strong plantar ligament is present
(1, 2). That goes from the caudal limit of the calcaneus to the fifth metatarsus. Into its
thickness the sesamoid bone appears. Obliquely oriented, the profound ligaments go from
sustentaculum tali to each metatarsus bone. The superficial fascicles, represented by the long
plantar ligament and the interoseous tendons create together a fibro-cartilaginous plaque that
strengthens the local region and offers the place for muscles insertion (fig. 5).
The heel articular complex executes mainly flexion and extension from the tibioastragalian.
The missing of the collateral ligaments, correlated with the aspect as an articular
head of the distal surface of the astragal, lead to the possibility of moving the foot medially
(1, 8). The rest of the bones form together with the metatarsian bones a little mobile articular
complex, determined by the plane or fragmented articular surfaces (fig. 4, 6).
The aspect of the distal articular surfaces of the last tarsian row, that is convex dorsoplantary,
and the presence of the short tarso-metatarsian ligaments, shows a reduced
possibility in moving. The articular consolidation is made by the joint capsule together with
the lateral and medial collateral ligaments each of them represented by anterior and lateral
short and strong fascicles (fig. 4, 5).
The sesamoid bones are articulated through the sesamo-phalanx and intersesamoidien
ligaments (2, 3, 8). By studying the form of the articular surfaces we can observe that the
proximal phalanx are articulated dorsally with the head of each metatarsus and the sesamoid
bones are plantary articulated with the condils of each metatarsus bones (fig 5).
CONCLUSIONS
The sacro-iliac joint is consolidated by the intraarticular ligaments, as well as by the dorsal and
ventral sacroiliac ligaments that are intersected with the periostal fibers and a bunch of two, three
ventral iliolumbar fasciles that are inserred between the ilium plaque and the transverses process
of the last lumbarum vertebra.
In flexion, the lateral meniscus slides caudally on the rounded articular surface of the tibial lateral
condile, aspect that permits the tibial rotation in the femur rapport.
The calcaneo-metatarsal ligaments are represented by the superficial and profound fibers the latter
going from the sustentaculum tali to each metatarsus bones.
The missing of the collateral ligaments of the heel joint correlated with the similar aspect to an
articular head of the astragalian distal articular surface, lead to the possibility of the medial foot
moving towards the medial plan.
BIBLIOGRAPHY
1. Necrasov Olga – Anatomia comparatã a vertebratelor, Ed. Didacticã si Pedagogicã, Bucuresti, 1971, p. 165-
169.
2. CoÑofan V., R. Palicica., Valentina HriÑcu, V. Enciu – Anatomia animalelor domestice, vol. I, Ed. Orizonturi
Universitare, Timisoara, 1999, p. 79-113, 201-211
3. Dyce, K.M, , W. O. Sack,, C.J.G. Wensing - Veterinary Anatomy, , III Edition, d. Saunders, Philadelphia,
ISBN 0-7216, 78966-3, 2002, p. 91-99, 467-477.
4. Spãtaru C., Mihaela Spãtaru – ArticulaÑiile membrului pelvin la capra domesticã (Capra Hircus). Lucr. St.
USAMV, Iasi, seria Med. Vet., vol. 45 (4), F. I, Ed. ,,Ion Ionescu de la Brad”, Iasi , 2002, p.44 -50. ISSN
1454-7406.
5. Spataru C., Mihaela Spataru, V. Vulpe – The functional peculiarities of the osteo-ligamentary and
acropodialy structures at domestic goat C.H. - Lucr. St. USAMV Timisoara, seria Med. Vet., vol. XXXV,
2002, p.65-67 . ISSN 1221- 5295.
6. Tudor Despina, Gh. M. Constantinescu - Nomina Anatomica Veterinaria, Ed a IV-a, Bucuresti, Ed. Vergiliu,
2002, ISBN 973-98540, p. 65-69, 78-83
7. Vulpe V., – Diagnosticul radiologic al afecÑiunilor articulaÑiei coxofemurale la câine. Simp. St. InternaÑional
,, 30 Ani de ÎnvãÑãmânt Medical Veterinar din Republica Moldova” Chisinãu 1-2 octombrie 2004. p. 224 -
225. ISBN 9975-9624-9-1.
8. Spataru C., Mihaela Claudia Spataru,D. Anitã - ParticularitãÑile anatomice ale pelvisului la ursul carpatin,
Lucr. St., vol 49, Med. Vet., Iasi, 2006, p. 33-37.
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