Gluteobiceps

• Origin: Spines of the sacrum, the sacrotuberal ligament, the ischiatic tuberosity at the rear end of the pelvis, and the fascia covering the gluteus medius and the tail.

• Insertion: Into the fascia of the leg, ultimately into the patella, the lateral patellar ligament, the front edge of the tibia, and the heel bone.

• Action: Extends the hip joint; extends the ankle joint; pulls the limb away from the body. With different portions, it both flexes and extends the knee joint.

• Structure: The gluteobiceps is a very large, roughly rectangular muscle, wide above and below, and narrower in the middle. Its front edge is thin, and its rear edge is thick. It is divisible into two portions—a large front portion passing from the hip region to the knee, and a long triangular rear portion beginning at the rear end of the pelvis. The division between these two portions is more visible near the pelvis, and it diminishes lower down, where the muscle fibers attach to the leg fascia. A long, narrow, tendinous band passes from the lower end of the muscle to the heel.

The gluteobiceps consists of the biceps femoris fused to the rear portion of the gluteus superficialis. It is not present in the horse, dog, or feline, where there are separate gluteus superficialis and biceps femoris muscles.

Biceps femoris

HORSE

• Origin: Long head: From the ligament connecting the sacrum to the ilium of the pelvis, in the vicinity of the third and fourth sacral spines, and from the surface of the gluteal muscles and the tail. Short head: Lower edge of the rear end of the pelvis.

• Insertion: All portions fuse deeply and then first insert into the back of the femur, about one third of the way down the bone. The lower ends of the muscle develop into a wide aponeurotic (tendinous) sheet that fuses into the fascia of the leg at and below the knee. The two heads ultimately insert as follows: Long head—into the patella and lateral patellar ligament. Short head/front portion—into the lateral patellar ligament and the front edge of the tibia. Short head/rear portion—into the leg fascia, and the end of the heel bone (calcaneus).

• Action: Entire muscle extends the hip joint (forward propulsion, kicking, rearing), and pulls the limb away from the body. The long head extends the knee joint, the short head/front portion flexes the knee joint, and the short head/rear portion flexes the knee joint and extends the ankle joint (extends the foot).

• Structure: The biceps femoris is a massive muscle that consists of a long head (long vastus) and a short head that separates into two portions, producing a total of three forms. The long head is crescent-shaped—widest at its center (where it covers the greater trochanter of the femur) and tapered at its ends. It begins at the top of the sacrum and ends at the level of the bottom of the patella. Its front edge is thin, whereas its rear edge is thicker and more clearly defined on the surface. The short head is a triangular volume that separates into two forms. Its front portion flattens and lies on the outside of the knee. The rear portion, which is thicker and rounder, ends distinctly on the surface of the outer side of the gastrocnemius muscle. A long, narrow tendon passes from the lower end of the biceps femoris muscle to the heel.

The semitendinosus muscle covers the rear edge of the upper half of the long head and the upper end of the short head. A strong vertical groove on the back of the thigh separates the biceps femoris from the semitendinosus.

• Origin: Superficial head: Outer corner of the ischiatic tuberosity at the rear end of the pelvis, and the rear third of the sacrotuberal ligament. Deep head: Bottom of the outer corner of ischiatic tuberosity, deep to the origin of the superficial portion.

• Insertion: Into the fascia of the leg, ultimately into the patella, the patellar ligament, the front edge of the upper end of the tibia, and the end of the heel bone (calcaneus).

• Action: The entire muscle extends the hip joint. The upper front fibers extend the knee joint, and the lower rear fibers extend the ankle joint and may also flex the knee joint.

• Structure: Large, wide muscle that begins narrow at the pelvis and then fans out to cover the rear portion of the outside of the thigh. Because its muscle fibers insert into a wide sheet of fascia that ultimately inserts further on, contracting muscle fibers pull on the fascia and may create raised ridges in line with the direction of those muscle fibers. This pulling can distort the volumes of the underlying muscles. The line where the muscle fibers attach to the fascia can occasionally be seen on the surface, which can also confuse the volumes of the muscles of the leg.

Along the rear edge of the muscle, new fibers begin deeply, wrap around to the outside, and then pass downward and forward on the surface. This structure may divide the overall muscle into several subtle forms.

A long, narrow tendon develops on the deep surface of the biceps femoris, emerges at its lower end, and descends along the surface of the gastrocnemius muscle. It eventually fuses with the Achilles tendon, which attaches to the heel bone (calcaneus).

FELINE

• Origin: Only from the ischial tuberosity, not from the sacrotuberal ligament.

• Structure: Because of its small point of origin, the biceps femoris assumes a more fan-shaped belly, and its fiber arrangement is simpler, than it is in the dog. It is divisible into a large front portion and a smaller rear portion.

The ox has no biceps femoris, but rather a gluteobiceps, which is an extensive, complex, single-bellied muscle consisting of the combined biceps femoris and gluteus superficialis.

FIRST TAIL VERTEBRA

Semimembranosus Muscle Dog

BICEPS fEMO RIS Long head Short head

TENDON TO HEEL

SACRUM

PATELLA

Long And Short Head Tendons

BICEPS FEM OR IS Long head Shorl held

[Front portion) [Rear part Ion}

Femoris Muscle Tail

REAR VIEW

[TENDON TO HEEL NOT SHOWN)

OUTSIDE VIEW FRONT

SACRUM

BICEPS fEMO RIS Long head Short head

PATELLA

TENDON TO HEEL

FIRST TAIL VERTEBRA

BICEPS FEM OR IS Long head Shorl held

[Front portion) [Rear part Ion}

OUTSIDE VIEW * FRONT

REAR VIEW

* OUTSIDE

[TENDON TO HEEL NOT SHOWN)

Biceps Femoris Equine

BICEPS F EM ORI S Superficial head

TENDON TO HEEL

Deep head

PATELLAR LIGAMENT

patella

SACROTUBERAL LIGAMENT

BICEPS F EM ORI S Superficial head

TENDON TO HEEL

PATELLAR LIGAMENT

patella

Deep head

SACROTUBERAL LIGAMENT

Semitendinosus Horse

ALL LEFT REAR LIMB

REAR VIEW OUTSIDE

Semitendinosus

HORSE

• Origin: First and second tail vertebrae, fascia of the tail, and the lower edge of the rear end of the pelvis.

• Insertion: Fascia of the inside of the leg, ultimately into the front edge of the tibia and the heel bone (calcaneus).

• Action: Extends the hip joint and the ankle joint; flexes the knee joint; rotates the leg inward.

• Structure: The semitendinosus is a long muscle that begins on the top of the base of the tail, passes down the back of the thigh, and ends on the inside of the upper end of the tibia. It forms the entire rear profile of the thigh in the horse. The muscle belly is triangular in cross section. The semitendinosus begins thin and narrow at the tail, and gets thicker as it descends. The lower end becomes thin again and flattened side-to-side, then terminates in a wide tendon that fuses with the fascia of the inside of the leg. A separate long, narrow, tendinous band passes from the lower end of the belly to the heel bone. The upper part (between the tail and the rear end of the pelvis) is unique to the horse.

A deep head originates from the rear end of the pelvis, but it soon fuses to the main body of the muscle.

• Origin: Only from the lower edge of the rear end of the pelvis.

• Structure: The fleshy muscle is elongated and slightly tapered at both ends. Its lower end is flattened side-to-side. The semitendinosus forms the lower edge of the rear profile of the thigh; the semimembranosus projects past it to form the upper edge.

DOG AND FELINE

• Origin: Outer corner of the rear end of the pelvis.

• Insertion: Front edge of the tibia, about one fourth of the way down the tibia, and the heel bone (calcaneus).

• Structure: This is an elongated muscle that passes between the rear end of the pelvis and the upper end of the inside of the knee region. Its lower end, flattened from side-to-side, sends off a wide tendon to the front edge of the tibia and a long, narrow one to the heel. The muscle belly lies on the middle of the back of the thigh and forms a very small part of the middle portion of the rear profile of the thigh. The semimembranosus forms the upper profile, and the biceps femoris creates the lower profile.

The semitendinosus descends in contact with the biceps femoris located to its outside. When they reach the back of the knee, the biceps femoris veers toward the outside (and descends lower), whereas the semitendinosus shifts inward. This leaves a triangular depression on the back of the knee.

Semimembranosus Animal

OUTSIDE VIEW 4 FRONT

REAR VIEW

1 OUTSIDE

HORSE

SEMIMEMBRANOSUS

Gracilis Semimembranosus Horse

sacrotuberal ligament

AIL LEFT REAR LIMB

Canine Upper Hind Leg Anatomy

SACROTUBERAL LIGAMENT'

sacrotuberal ligament

AIL LEFT REAR LIMB

HORSE

SEMIMEMBRANOSUS

Horse Profile Anatomy

Semimembranosus

HORSE

• Origin: Rear free edge of the sacrotuberal ligament (passing from the second tail vertebra to the top of the rear end of the pelvis) and the lower edge of the rear end of the pelvis.

• Insertion: Inner surface of the lower end of the femur.

• Action: Extends the hip joint; pulls the limb toward the centerline of the body.

• Structure: The semimembranosus is a large, thick muscle located on the rear portion of the inside of the thigh, where most of it comes to the surface. It runs alongside the semitendinosus and is partly covered by the gracilis, mostly at its lower end. The muscle begins at the base of the tail and ends on the inside of the knee. Pointed on its upper end, the descending muscle belly is joined by a deep head that originates from the rear end of the pelvis. The upper end of the muscle, between the tail and the pelvis, is unique to the horse. The semimembranosus is not seen in the side view of the thigh (it does not form part of the rear profile).

• Origin: From the lower edge of the rear end of the pelvis only, but from a more extensive area than in the horse.

• Insertion: Inner surface of the lower end of the femur, and the inner surface of the uppermost end of the tibia.

• Structure: The semimembranosus in the ox more closely resembles this muscle of the dog than the horse. The lower end splits and sends a major portion to the femur and a smaller portion to the tibia. This separation and insertion is deep and not visible on the surface.

The upper end of the belly slightly projects past the semitendinosus to form the upper portion of the rear profile of the thigh.

DOG AND FELINE

• Origin: A line on the lower edge of the rear end of the pelvis.

• Insertion: A vertical line on the inner back comer of the lower end of the femur, ending a short distance from the bottom of the bone, and a small area on the inner side of the uppermost end of the tibia.

• Structure: This is a thick fleshy muscle consisting of two heads. One head inserts into the femur, while the other crosses the knee joint and inserts into the tibia. The belly comes to the surface on the upper, inner rear corner of the thigh, between the semitendinosus and the gracilis. The upper portion of the muscle projects past the semitendinosus to form the upper portion of the rear profile of the thigh.

Gracilis Horse

REAR VIEW INSIDE VIEW REAR VIEW

Gracilis HORSE

• Origin: Front two thirds of the line of fusion of the two halves of the pelvis, on the midline on the bottom of the pelvis (variously from bone, ligament, and tendon).

• Insertion: Medial patellar ligament, inner surface of the tibia, and the fascia of the leg.

• Action: Primarily pulls the limb toward the centerline of the body; extends the hip joint.

• Structure: The gracilis is a wide, thin, somewhat rectangular muscle lying on the rear portion of the inner side of the thigh. This flat muscle thins toward its rear edge. It shares its origin with the same muscle of the other leg; the upper ends of the two muscles are in contact with each other when the animals is in the standing position. The muscle belly ends below, developing a wide tendon that fuses with the fascia of the leg.

• Insertion: Also to the heel bone.

• Action: Also extends the ankle joint.

• Structure: The lower end of the muscle belly also sends a tendinous band to the heel bone.

DOG AND FELINE

• Origin: Line on the midline on the bottom of the pelvis that veers outward as the rear projections of the pelvis diverge.

• Insertion: Ultimately into the front edge of the tibia and into the heel bone.

• Action: Also flexes the knee joint and extends the ankle joint.

• Structure: The muscle thickens toward its rear edge, opposite to that of the horse. The muscle belly is also narrower than in the horse. In addition to the tendon to the front of the tibia, the lower end of the belly sends a tendinous band back to the heel bone, along with the semitendinosus.

Dog Bone Structure Front View

FRONT VIEW OUTSIDE ►

Tibialis Cranialis

Alt LEFT REAR LIMB

FRONT VIEW OUTSIDE ►

INSIDE VIEW FRONT »-

Alt LEFT REAR LIMB

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INSIDE VIEW FRONT »-

Tibialis cranialis (Tibialis anterior in humans) HORSE

• Origin: Upper end of the outer side of the tibia, including the concavity and adjacent bony prominences, and the fascia of the leg.

• Insertion: Front of the upper end of the large metatarsal bone, and the inside back corner of the ankle (into the rear bone on the lower tarsal row).

• Action: Flexes the ankle joint.

• Structure: The tibialis cranialis is a flattened muscle lying on the front of the tibia. Its flat face is directed forward and outward; the extensor digitorum longus and the peroneus tertius lie on this surface. The muscle begins fleshy above and becomes tendinous below. In front of the ankle, its tendon emerges through the perforated tendon of the overlying peroneus tertius, and then splits, sending one branch straight down and the other around to the inside of the ankle.

Only the inner edge of the muscle belly is visible on the surface between the tibia and the extensor digitorum longus. The inner branch of the tendon can be seen when the ankle is flexed.

• Structure: The tibialis cranialis is a thinner and more concealed muscle than in the horse. Only the upper end of the belly, between the tibia and the peroneus tertius, and the tendon, is superficial. The tendon remains single and veers to the inside of the ankle to attach into adjacent areas on the lower row of tarsal bones and the upper end of the large metatarsal. It pierces the tendon of the peroneus tertius, as in the horse.

DOG AND FELINE

• Origin: Vertical line on outer side of tibia, just to the outside of the front edge, continuing up into the concavity at the top of the outside of the bone. Feline: Also into the upper end of the fibula.

• Insertion: Dog: Inner edge of the foot, into the lower tarsal bone and the adjacent upper end of the inner metatarsal. Feline: Into the metatarsal only.

• Action: Flexes the ankle joint; rotates the foot slightly outward.

• Structure: This elongated muscle is wider at its upper end. In the dog, it develops a flat tendon two thirds of the way down the bone. In the feline, the lower end of the muscle belly becomes tendinous closer to the ankle than in the dog, covering more of the belly of the extensor digitorum longus. The tendon descends and then veers inward, crossing the front of the foot, and then ends on the inner edge of the foot. The slightly flattened belly sits on the outer front edge of the lower leg and wraps (side-to-side) around the underlying muscles. The tibialis cranialis is not covered by the extensor digitorum longus and the peroneus tertius, as it is in the horse and the ox.

FRONT VIEW OUTSIDE ►

PERONEUS TERTIUS

Peroneus Tertius Horse

OUTSIDE VIEW < FRONT

HORSE

PERONEUS TERTIUS

FRONT VIEW OUTSIDE ►

PERONEUS TERTIUS

FRONT VIEW OUTSIDE ►

HORSE

ALL LEFT REAR LIMB

OUTSIDE VIEW < FRONT

PERONEUS TERTIUS

Peroneus tertius (Fibularis tertius)

HORSE

• Origin: From a depression on the outer surface of the very bottom of the femur.

• Insertion: Upper front end of the large metatarsal bone and the front of the tarsal bone above it; the outside of the ankle, into the base of the heel bone and the adjacent tarsal bone just below it.

• Action: Rigid cable that forces the ankle joint to flex when the knee joint is flexed.

• Structure: The peroneus tertius is a strong tendon, devoid of any muscle fibers, which begins on the femur and ends on the ankle. Sandwiched between the bellies of the tibialis cranialis and the extensor digitorum longus on the front of the lower leg, it emerges from between them approximately two thirds of the way down the leg. At the level of the bottom of the tibia, the peroneus tertius is perforated, and the tendon of the underlying tibialis cranialis emerges through this hole. The peroneus tertius then continues straight down to the metatarsal bone. Below the level of the perforation, it sends off a small tendinous branch that passes around to the outside of the ankle, splits, and then attaches to the outside of the ankle.

The peroneus tertius has virtually no effect on the surface, but is presented here because its lower end is superficial, and for comparison with the same muscle of the ox.

• Insertion: Inner front corner of the upper end of the large (fused) metatarsal; inner rear corner of the ankle, into several adjacent bones, including the upper end of the large metatarsal bone.

• Action: Flexes the ankle joint.

• Structure: The muscle has a fleshy, slightly flattened belly, rather than just a tendon, as in the horse. It lies superficially on the front of the lower leg. Passing from the knee to the ankle, it begins and ends with tendons; its muscle belly is pointed at both ends. At the level of the lower end of the tibia, the tendon is perforated, allowing the tendon of the underlying tibialis cranialis to emerge, as in the horse. Below the perforation, it sends a tendinous branch to the inside of the ankle (opposite that of the horse). The peroneus tertius covers most of the extensor digitorum longus and is closely adherent to it.

The peroneus tertius is not present in the dog or the feline; the extensor digitorum lateralis has in the past been called the peroneus tertius.

Cat Tibialis Cranialis

EXTENSOR DIGITORUM LONGUS

EXTENSOR DIGITORUM LONGUS

Fibularis Tertius Cat Anatomy

EXTENSOR DIGITORUM LONGUS

■ EXTENSOR■ DIGITORUM LONGUS

FRONT VIEW

OUTSIDE VIEW

FRONT VIEW

OUTSIDE VIEW

< FRONT

■ EXTENSOR■ DIGITORUM LONGUS

FRONT VIEW

Extensor digitorum longus (Extensor pedis) HORSE

• Origin: From a depression on the outer surface of the very bottom of the femur, in common with the tendon of the peroneus tertius.

• Insertion: Upper edge of the front surface of all three toe bones, primarily into the last.

• Action: Extends all three toe joints; flexes the ankle joint.

• Structure: The extensor digitorum longus is a long muscle with a very long tendon that passes from the femur to the last toe. The slightly flattened muscle belly, tapered at both ends, lies on the outer front corner of the lower leg. It becomes tendinous above the level of the ankle joint. The long tendon lies on the front of the leg bones and disappears under the hoof. Halfway down the metatarsal bone, the tendon is joined by the tendon of the extensor digitorum lateralis. Lower down, on the upper toe bone, both edges of the tendon receive branches from the suspensory ligament.

• Insertion: Upper edge of the front surface of the last toe bone of both toes, and the upper edge of the middle toe bone of the inner toe.

• Structure: The muscle is much thinner than in the horse, and also more concealed, as its inner portion is covered by, and closely adheres to, the peroneus tertius. The muscle, overall, is pointed at both ends and consists of two bellies, each of which develops a long tendon at the level of the ankle joint. The inner tendon inserts into the inner toe. The outer tendon splits at its lower end and inserts into both toes.

DOG AND FELINE

• Insertion: Last toe bone of all four digits.

• Structure: The upper end of the belly of the extensor digitorum longus is covered by the tibialis cranialis and the peroneus longus. The extensor digitorum longus then emerges from between them, one third of the way down the tibia. It becomes tendinous before reaching the ankle joint, and then travels alongside the tendon of the tibialis cranialis for a short distance. The tendon of the tibialis cranialis soon moves away, veering to the inside of the ankle. The tendon of the extensor digitorum longus then separates into four tendons, one for each toe.

In the feline, the belly of the tibialis cranialis is wider and descends lower than in the dog, thereby covering more of the extensor digitorum longus, which closely adheres to it. This leaves the outer part of the lower portion of the extensor digitorum longus visible on the surface. The muscle fibers of the belly continue down to the level of the ankle joint before it becomes tendinous.

Equine Anatomy Calcaneus

FRONT VIEW OUTSIDE ►

OUTSIDE VIEW A FRONT

OUTSIDE VIEW < FRONT

OUTSIDE VIEW < FRONT

FRONT VIEW OUTSIDE ►

OUTSIDE VIEW A FRONT

OUTSIDE VIEW < FRONT

OUTSIDE VIEW < FRONT

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Responses

  • DENNIS CLINE
    Where are the semimembranosus located on a dog?
    8 years ago
  • ky
    What muscles are affected when dog is band legged and base wide front?
    8 years ago
  • ZAHRA
    Which is visible semitendinosus and semimembranosus?
    7 years ago
  • maxima burrowes
    Where is the fibularis tertius on the horse?
    7 years ago
  • Casimiro
    Where is gracilis tendon?
    6 years ago

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