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CLINICAL ANATOMY OF THE PREPUBIC TENDON INTHE DOG AND A COMPARISON WITH THE CAT
INTRODUCTION
n The objectives of this paper are to show in the most
detailed manner the composition of the prepubic
tendon in the dog, its relationships with the
neighboring structures and clinical correlations for
diagnosis and surgical treatment of any pathological
condition.
n This is not a comprehensive review. The paper
focused on clinically important details not mentioned
before. A review based on selected references is
suggested prior to surgery.
n The prepubic tendon is a dense mass of collagenous
tissue which serves as the attachment for the ventral
abdominal muscles on the cranial border of pubis (the
pecten of pubis).
n The prepubic tendon is a complex of tendons, mainly
of musculi pectinei and musculi recti abdominis
attached to rami craniales ossium pubis ¹,
81
Cercetãri Experimentale & Medico-Chirurgicale
Anul XIV · Nr.2-3/2007 · Pag. 81-85 C e r c e t a r ie x p e r i m e n ta le &
m edico-chirurgicale
)
SUMMARY:Several authors were interested in the structure of the prepubic tendon in the dog in the lastcentury. No similar structure was found in the cat. The descriptive anatomy of the prepubictendon was either superficially or not correlated at all of to the clinical aspects of theveterinary medical profession. The implication of this structure in the pathology of the areais of high importance, considering that the physical examination and the surgical techniques should be correctly applied not only on to the prepubic tendon, but also to the neighboringstructures, such as the superficial inguinal ring and the inguinal canal with its content.
Key Words: prepubic tendon, superficial inguinal ring, dog, cat
ANATOMIA CLINICÃ A TENDONULUI PREPUBIAN LA CÂINE ÎN COMPARAÞIE CUPISICA
REZUMAT: Câþiva autori au fost interesaþi de structura tendonului prepubian la câine în secolul trecut.La pisicã nu a fost gasitã o structurã similarã. Anatomia descriptivã a tendonului prepubian a fost tratatã fie superficial, fie nu a fost corelatã cu aspectele clinice ale profesiunii medicalveterinare. Implicazþia acestei structuri în patologia ariei anatomice este de o mareimportanþã, þinând cont de faptul ca examenul fizic ºi tehnicile chirurgicale trebue sa fieaplicate corect nu numai asupra tendonului prepubian, dar de asemenea ºi asuprastructurilor vecine, ca de exemplu inelul inguinal superficial ºi canalul inguinal cu conþinutulsau.
Gheorghe M.Constantinescu1,Menolly R. Beittenmiller2,F. A. Mann3
Ileana A.Constantinescu4
Received for publication: 25.04.2007
Revised: 11.08.2007
1- DVM, PhD, mult. Drhc, Professor, Dept. of Biomedical Sciences, College of Veterinary Medicine, University of Missouri,2- Senior Student, College of Veterinary Medicine, University of Missouri3-DVM, MS, Diplomate ACVS, Diplomate ACVECC, Professor, Dept. of Veterinary Medicine and Surgery, College ofVeterinary Medicine, University of Missouri4 - DVM, MS, Clinical Assistant Professor, Dept. of Biomedical Sciences, University of Missouri
Correspondence to: Gheorghe M.Constantinescu ,Dept. of Biomedical Sciences, College of Veterinary Medicine, Universityof Missouri, 1600 E. Rollins, Columbia, MO 65211-5120 USA, e-mail: [email protected]
n The prepubic tendon, which has also been called
“cranial pubic ligament” similar to the “superior
pubic ligament” in humans ² serves as a point of
attachment for the ventral abdominal musculature
onto the pelvis. In this capacity the prepubic tendon
aids in the action of the abdominal press which
makes possible the acts of expiration, urination,
defecation, and parturition ³.
n This structure has been described numerous times in
the dog, but a homologous structure is not present in
the cat 4.
n It is imperative to have a thorough knowledge of the
prepubic tendon and the neighboring structures to
diagnose correctly any pathological condition and to
use the appropriate surgical technique for repair.
MATERIAL AND METHODS
Two fresh and eight embalmed dogs, three fresh and
seven embalmed cats were used in this study. The fresh
specimens were provided from a Humane Society,
whereas the embalmed specimens were first used by the
students in the dissection room, and were provided either
by different companies or embalmed in our Anatomy
Laboratory. In this case the embalming fluid had the
following formula:
1200 ml Formaldehyde
400 ml Propylene or Ethylene glycol
1000 ml Phenol
add water to 20 liters
RESULTS
According to our findings, Fig. 1 shows the superficial
level of structures beneath the skin and the
subcutaneous connective tissue. The right external and
internal abdominal oblique muscles were reflected from
the linea alba to expose the rectus abdominis muscle.
The superficial inguinal ring, the femoral lamina, the
femoral triangle and the corresponding vessels are
shown. We should first mention that at the very cranial
border of the pubic bones a poorly developed cranial
pubic ligament connects the symmetrical pecten of pubic
bones; in some cases this ligament was not present.
According to our findings, the transversus abdominis
muscle did not attach to the prepubic tendon. Its caudal
border, called “Linea arcuata” ended cranial to the pecten
of pubis. The point of attachment of the prepubic tendon
and of the aforementioned muscles on the pubis was not
the median ventral pubic tubercle. Only the medial part of
muscular fibers of the rectus abdominis muscle attached
to the ventral pubic tubercle (Fig. 2). The largest lateral
part of the rectus abdominis muscle, and the
aponeuroses of the two abdominal oblique muscles
attached to the pecten of pubis (see Fig. 2). The lateral
part of the rectus abdominis muscle was provided with
an elliptically shaped aponeurosis overlapping muscle
fibers (see Fig. 2). The aponeurosis sent fibers that
passed over and under the prepubic tendon (see Fig. 2).
The two crura of the superficial inguinal ring (from the
82
external abdominal oblique muscle) were strong and
attached to the prepubic tendon and the pectineus
muscle (the medial crus to the tendon, while the lateral
crus to the muscle fibers of the pectineus) (see Fig. 2).
The prepubic tendon has been shown to extend from
the pecten to the iliopubic eminence on either side, but
little cross-over of fibers was noted in dogs. The structure
of the prepubic tendon in the dog is most similar to that
seen in ungulates; however, one significant difference
noted in the dog is the incorporation of the iliopubic
cartilage which was found to be intercalated in the
pectineus tendon 5 .
In the cat, the abdominal and pectineus muscles had
separate attachments to the pubis and thus, a prepubic
tendon does not exist. However, based on our findings
the two crura of the superficial inguinal ring were as
strong as to firmly attach on the cranial border of pubis on
both sides of the insertion of the pectineus muscle on the
iliopubic eminence (Fig. 3). We noticed three-four strong
attachments of the aponeurosis of the external
83
abdominal oblique muscle on the medial aspect of the
thigh: the most lateral attachment is the continuation of
the lateral crus of the superficial inguinal ring, whereas
the other attachments originate from the medial crus of
the ring and the aponeurosis of the muscle itself ( Fig. 3).
The aponeurosis of the external abdominal oblique
muscle sent in addition a strong attachment to the tendon
of the pectineus muscle (Fig. 4).
COMMENTS AND CLINICALCORRELATES
Developmentally, the prepubic tendon is stronger in
species with a heavy abdominal mass and proportional
with the volume of the abdominal viscera, such as the
ruminants and the horses. In carnivores this structure is
less developed. The aponeurotic attachments of the
ventral abdominal muscles pull the prepubic tendon
ventro-cranially, in an angle that varies with the species
and the weight of the abdominal mass. In humans,
vertical posture changed the angle and the relationship of
the attachment of the ventral abdominal muscles. Thus,
there is no prepubic tendon in humans, but a superior
pubic ligament. The latter is attached to the superior
border of the pubic bones and joins the symmetrical
pecten of pubic bones overlapping the interpubic disc. In
addition, in humans the pubic attachment of the rectus
abdominis muscles is doubled ventrally by a dependence
of the aponeuroses of the external abdominal oblique
muscles, and dorsally by an enlargement of linea alba
called “adminiculum lineae albae” 6.
In domestic mammals the prepubic tendon is a strong
fibrous structure attached to the cranial border of the
pubic bones, between the symmetrical iliopubic
eminences. In comparison to humans the prepubic
tendon of domestic mammals allows the attachment of
linea alba and the tendons of some ventral abdominal
muscles to the pubis.
The prepubic tendon is defined by one author, not
specifically for the dog, as “a strong squared fibrous
blade attached to the cranial border of the pubic bones,
from one iliopubic eminence to the other. As a complex
structure, it extends directly the linea alba and the
tendons of recti abdominis muscles, and receives part of
the aponeurotic fibers of the symmetrical abdominal
oblique and transverse abdominal muscles. Besides, it
maintains connections, important in ungulates, with the
origin of some muscles of the thigh, such as the
pectineus and gracilis” 6. If we elim i nate “im por tant in
ungulates” and “gracilis”, the def i ni tion may by ap plied to
the dog.
Specifically for the dog the prepubic tendon is defined
by another author as “a strong collagenous mass
composed primarily of the tendons of the paired rectus
abdominis muscles and the tendons of origin of the paired
pectineus muscles. It is firmly attached to the median
ventral pubic tubercle” 3.
Our dissections showed that only the medial part of
muscular fibers of the rectus abdominis muscle attaches
to the ventral pubic tubercle and the largest lateral part of
the rectus abdominis muscle, and the aponeuroses of the
two abdominal oblique muscles attach to the pecten of
pubis.
“An iliopubic cartilage is intercalated in the prepubic
tendon at the junction between the symmetrical
84
pectineus tendon and the external abdominal oblique
tendons at the caudal angle of the superficial inguinal
ring” 5.
Our dissections showed that the iliopubic cartilage is
located between the caudal commissure of the
superficial inguinal ring and the muscular, not the
tendinous part of the pectineus muscle, which should be
given a different consideration in surgery.
In the cat the strong attachments of the two crura of
the superficial inguinal ring on the cranial border of the
pubis on each side and together with the tendon of the
pectineus muscle seems to be as strong as the prepubic
tendon of the dog.
A prepubic tendon is considered not to be present in
any species in which the pectineus and adductor longus
muscles are separate including humans, primates,
rabbits and some rodents 5. This is not true, because in
some dogs the adductor longus is a muscle totally
separated from the pectineus 3.
Based on our anatomical findings and the nature of the
prepubic hernia in dogs and cats 7,8 precise
reconstruction of this anatomy after traumatic injury is
unlikely. However, reattachment of the anatomical
musculature with suture, usually through holes drilled
into the pubis, results in repair of the hernia with high
success 7. Apparently, healing with scar tissue is
sufficient to mimic the function of the prepubic tendon
and related anatomy.
85
REFERENCES
1. Schaller O. et al, 1992: Illustrated Veterinary Anatomical Nomenclature, Enke, Stuttgart2. Feneis H., Dauber W., 2000: Pocket Atlas of Human Anatomy Based on the International Nomenclature, 4th ed., Thieme,
Stuttgart, New York3. Evans H.E., 1993: Miller’s Anatomy of the Dog, 3rd ed., Saunders 4. Budras K.-D.: Leistenband, Leistenkanal und M. cremaster externus der Katze. Anat. Anz. 1967, 121:148-1655. Habel R.E., Budras K.-D.: Anatomy of the prepubic tendon in the horse, cow, sheep, goat, and dog. Am J Vet Res 1992, 53, 11,
2183-21956. Barone R., 2000: Anatomie comparée des mammifères domestiques tome 2 Arthrologie et Myologie, Vigot, Paris7. Mann FA, Tangner CH, Boothe HW, Weber WJ : Cranial pubic ligament rupture in dogs and cats. J Am Anima Hosp Assoc
1986, 22, 519-5248. Friend EJ, White RAS: Rupture of the cranial pubic tendon in the cat. J Small Anim Pract. 2002, 43, 522-525