Where is pes anserinus

The pes anserinus PA is composed of the combination of tendinous insertions of the sartorius, gracilis, and semitendinosus muscles. These three muscles attach to the medial side of tibia to generate a shape reminiscent of a goose's foot, which is the literal meaning of its name. This structure is clinically important in the reconstructive surgery involving tendons or in the steroid injection for anserine bursitis AB.

The PA tendons are commonly used as autografts in ligamentous reconstruction of the knees [ 1 , 2 ]. The main advantage of this approach is the low donor side morbidity and the fact that harvesting PA tendons does not lead to any clinical or functional deficits [ 1 ].

However, a minimally invasive surgery demands an understanding of the exact locations of PA tendons from the insertion site. There have been anatomical studies investigating on the shapes of the PA in various populations [ 1 , 2 , 3 ].

The present study sought to determine in detail the relation between the relative positions and shapes of the insertion site and the PA, in a Korean population. The anserine bursa is located at the upper medial aspect of the tibia, at the insertion of the conjoined tendon of the PA muscles.

The AB can often be the source of discomfort in patients experiencing knee pain [ 4 ]. The AB has been clinically diagnosed in In contrast, Steroid injection in the bursa is a method to treat bursitis that can provide pain relief [ 4 , 6 , 7 , 8 , 9 ]. The accuracy of anserine bursa injection with ultrasound-guidance is markedly higher compared to the blind injection [ 10 ].

In clinical practices, however, surgeons are often confronted with the situations requiring blind injections, although they are well-aware that the ultrasound-guided injection is highly preferred.

In the case of a blind injection, understanding and identifying the recommended site based on the anatomical knowledge would be very helpful. Prior studies have investigated the human bursa [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ], but the anatomical information of anserine bursa was limited.

In this reason, The aim of this study was to identify the boundary of the anserine bursa to determine the recommended injection site and the shape of the insertion area of PA.

The present study aimed to investigate the shape of a footprint of the PA, 60 embalmed and 26 non-embalmed specimens from 45 Korean adult cadavers 26 males and 19 females, age range of years, and height range of cm. An incision was made at the knee area on the antero-medial surface.

After removing the skin around the knee, the insertion site of the PA tendons was exposed completely and was carefully dissected to identify the shape of the PA. The width of the insertion site was measured and the shape of the insertion site was recorded with photographs and by drawing. Water was sprayed on the cadaver during dissection to prevent them from drying. The measurements of the PA were performed as follows Figs. Sartorius tendon variation at the insertion site. Some parts of the sartorius tendon were inserted into deeper layer than the gracilis and semitendinosus tendons arrow.

Typical insertion site of the pes anserinus. Dotted line denotes the inferior border of the sartorius muscle. A Semitendinosus was attached to the inner space of the inferior borders of sartorius. B Semitendinosus was attached inferior to the Sartorius. Variation of the semitendinosus tendon at the insertion site. A The semitendinosus tendon was divided into two. B The semitendinosus tendon was divided into three. To investigate the anserine bursa, 34 non-embalmed specimens from 18 Korean adult cadavers 9 males and 9 females, same ranges in age and height as previously noted were studied.

The skin and soft tissue around the knee area were removed. To find the best injection site in the anserine bursa, various methods were explored in the preliminary study. The optimal location for injection, which was presently used for all specimens, was 20 mm medial from the IMPTT, with the superior border of sartorius from that point used as the injection site.

A solution of 26 ml containing 5. The nerves and vessels on the anserine bursa were traced to determine their distribution Figs. After checking the shape of PA at the insertion site, the shape of bursa was determined and recorded as described above.

The measurements of the anserine bursa are as follows:. The injection method in the anserine bursa. The anserine bursa revealed by injection of gelatin containing blue ink. The distribution of nerves and vessels in the anserine bursa. A single observer made all measurements using a digitalized caliper Absolute Digimetric, Mitutoyo Corp, Kanagawa, Japan.

Also, we divided into 9 parts on the basis of maximum and minimum points on the bursa. Then, we investigated the frequency of the passage of vessels and nerves in each of the 9 parts for all specimens, and the frequency was presented in percentage Fig. All metric data were analyzed by using SPSS version Comparisons between males and females were performed by using the t -test. The insertion width of the sartorius on the medial side of the tibia was 32 mm range, The average tendon width was 7.

The sartorius tendon was inserted in the superficial layer, and the gracilis and semitendinosus were inserted deeper on the medial surface of tibia. In one specimen, some parts of sartorius tendon were inserted deeper than the gracilis and semitendinosus tendons Fig.

The semitendinosus tendons were usually connected to the deep fascia of the leg. It is fused with the periosteum over the subcutaneous surfaces of the bones. Overall, the shape of anserine bursa was irregularly circular. However, 8 out of 34 specimens had location at 20 mm above the proximal line of the tibia. In the medial view of the tibia, the anserine bursa was located posteriorly and superiorly from the tibia's midline, and it followed the lines of the sartorius muscle Fig.

When the bursa was divided into 9 parts, area C2 contained the largest number of nerves and vessels. Area A2 and A3, which corresponded to the injection point, contained only 6. The present findings echo those of Laprade et al. The average widths of the PA tendons in the previous and present studies differ by only 1. Variations such as an accessory band of the gracilis and semitendinosus were frequent. Another study using 10 human cadaveric specimens reported that the accessory bands may arise from these two muscle tendons and insert separately into the PA [ 1 ].

The latter study [ 1 ] reported with dissections of accessory bands in all gracilis and semitendinosus tendons. In one specimen, the sartorius tendon was inserted in bifid form to the tibia Fig. Mores study in detail should prove many useful findings applicable to the reconstructive surgery.

Many cases involving pain in the PA insertion region are diagnosed as PA tendinitis or bursitis syndrome. The diagnosis is entirely based on clinical manifestations marked by spontaneous medial knee pain on climbing or descending stairs, tenderness at the PA insertion, and occasional local swelling [ 5 ]. The incidence of AB is higher in women; overweight individuals; individuals with osteoarthritis of the knees, valgus deformities, and pes planus; and those of years of age, although younger obese women can also be affected [ 7 , 9 ].

Presently, the proximal boundary of the anserine bursa was 10 mm medial from the IMPTT and the distal boundary continued in the postero-superior direction in relation to the tendons of PA Fig. The bursa of almost all specimens reached the proximal tibial line, but 8 of the specimens reached 20 mm above the line. These results may lead to further studies for useful understanding and treatment of AB.

Some of the present specimens displayed infrapatellar nerve near the bursa from the saphenous nerve and vein in the inferior direction. However, this was not related to the injection site, which was located 20 mm medially from the IMPTT. Pes anserinus rare plural: pedes anserini is the anatomic name given to the conjoined tendons at the medial aspect of the knee that inserts onto the anteromedial aspect of the tibia. The term "pes anserinus" may also be used to describe the branching point of the facial nerve CN-VII within the parotid gland.

See here for mnemonics for remembering the three conjoined tendons that make up the pes anserinus. These tendons insert onto the anteromedial proximal tibia approximately 4 cm distal to the tibial plateau 2. The pes anserinus inserts on the medial side of the tibial tuberosity below or distal to the tibial tuberosity with significant variant anatomy 3,4 , comprising mostly different accessory tendinous bands appearing from the different tendons. The type of insertion can be classified into a short, band-shaped and fan-shaped, with fan-shaped defined as the insertion being two times the width of the tendon and band-shaped being less than two times the tendon width 3.

The sartorius tendon insertion usually has a short tendon insertion, the gracilis tendon and its accessory bands show most often ca. The pes anserinus bursa lies between the pes anserinus tendons and the more deeply located semimembranosus tendon at the level of the knee joint.

This bursa can become inflamed and symptomatic: pes anserinus bursitis. The variant anatomy is of particular clinical importance since the pes anserinus serves a harvest site for tendon grafts e.

In respect to the accessory bands, the majority seem to emerge from the semitendinosus tendon 3,4. The accessory bands usually insert on the gastrocnemius or popliteus fascia 3.

Some of the accessory bands of the semitendinosus muscle emerge up to 12 cm proximal to the pes anserinus insertion 3. The name comes from the Latin for goose's foot, in view of the similarity of the structure to the webbed foot of the bird. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys.

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