Mylohyoid

Forward Head Posture Fix

Forward Head Posture Fix

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DOG AND FELINE

• Origin: Inside surface of the lower jaw, just below the tooth sockets.

• Insertion: Into the same muscle of the other side, along the midline, and then into the hyoid bone.

• Action: Raises the floor of the mouth and the tongue; pulls the hyoid bone forward.

• Structure: The mylohyoid forms the downward bulging floor of the mouth. Both sides together form a sling under the lower jaw. This sling drops down below the level of the lower jaw and therefore forms part of the profile of the throat when not obscured by loose skin folds.

The mylohyoid of the ox may drop slightly below the lower edge of the jaw, whereas in the horse is does not, and therefore does not participate in creating the profile.

Jugular Furrow Horse AnatomyManubrium Dog Anatomy

Sternocephalicus

The sternocephalicus ("sternum-to-head" muscle) is the general name for the muscle that begins on the front end of the sternum (the manubrium) and ends on various parts of the skull. When it inserts onto the lower jaw, or mandible, it is called the stemomandibularis; onto the mastoid process on the base of the skull, the sternomastoid; and onto the occipital bone on the upper rear edge of the skull, the sterno-occipltalis.

HORSE (Stemomandibularis)

• Origin: Cartilage at the front end of the sternum.

• Insertion: Halfway down the rear edge of the lower jaw.

• Action: Both sides together: Pull the head and neck downward. One side only: Pulls the head and neck to that side.

• Structure: The stemomandibularis is a long narrow muscle that passes up the neck from the midline on the front of the chest to the rear edge of the lower jaw. The muscles on each side of the body are initially in contact with each other beginning at the sternum; they then begin to separate and diverge one half to two thirds of the way up the neck. At its upper end, the muscle narrows and then disappears under the parotid gland, which lies on and behind the rear edge of the lower jaw. The jugular vein is located between the stemomandibularis and the brachiocephalicus. At a level just above the bottom of the lower jaw, the jugular vein sends a branch forward, which lies on the upper end of the sternocephalicus. This venous branch can appear as a furrow on the surface.

OX (Stemomandibularis and Sternomastoid)

• Origin: Front end of the sternum and the cartilage of the first rib.

• Insertion: Stemomandibularis: Lower edge of the lower jaw and the

Jugular Furrow Equine

surface of the front edge of the masseter muscle. Sternomastoid: Base of the skull in the region behind the ear hole.

• Action: See above. Also opens the mouth by pulling the lower jaw downward.

• Structure: The sternocephalicus consists of two separate muscles— the stemomandibularis, which attaches to the lower jaw, and the sternomastoid, which attaches to the base of the skull. For most of the neck, the two muscles parallel each other; the sternomastoid lies to the inside of, and is partly overlapped by, the stemomandibularis. Below and behind the angle of the jaw, the sternomastoid continues upward, passing under the stemomandibularis on its way to its higher and deeper insertion on the base of the skull. The sternomastoid muscles of both sides of the body are in contact with each on the lower third of the front of the neck, where they come to the surface. Here they lie between the stemomandibularis muscles, which are not in contact with each other.

DOG AND FELINE (Sternocephalicus)

• Origin: Front end of the sternum, in common with the muscle of the other side of the body.

• Insertion: Sterno-occipitalis: Upper edge of the rear end of the skull. Sternomastoid: Base of the skull behind the ear hole (mastoid process).

• Structure: Most of the sternocephalicus, from its origin upward, is a single belly. Near the head, it separates into the wider, thinner sterno-occipitalis, and the tapering sternomastoid. The sternomastoid lies to the front of the sterno-occipitalis; it inserts on a deeper plane onto the base of the skull behind the ear hole. The sternocephalicus muscles of both sides of the body are in contact with each other for a short distance above the sternum before they diverge.

Nuchal Ligament

Rhomboid

HORSE

• Origin: The side of the lower two thirds of the nuchal ligament and the tips of the upward projections of the thoracic vertebrae and intervening ligament to the seventh thoracic vertebra.

• Insertion: Inner surface of the cartilage of the shoulder blade.

• Action: Pulls the upper end of the shoulder blade upward, forward, and against the body. When the shoulder is fixed, it lifts the neck; one side only pulls the neck to that side.

• Structure: The rhomboid is an irregular four-sided muscle with an extremely pointed front end. It consists of two parts (neck and chest parts), which are continuous, and is here treated as a single structure. The portion on the neck is long and narrow. Its tip is superficial—the remainder can be distinctly seen under the trapezius as an elongated triangular form, widest where it meets the shoulder blade.

• Origin: The side of the rear two thirds of the nuchal ligament and the tips of the upward projections of the thoracic vertebrae and intervening ligament to the fifth thoracic vertebra.

• Structure: The rhomboid is completely covered by the trapezius. Its form can be detected as an elongated triangle on the side of the neck, under cover of the trapezius.

DOG AND FELINE

• Origin: Midline on the back of the neck and shoulder from approximately the second neck vertebra to the sixth thoracic vertebra; base of the skull.

• Insertion: Upper edge of the shoulder blade.

• Structure: The rhomboid is also covered completely by the trapezius. It is thicker in the dog and the feline than in the horse and the ox. The neck portion sends a separate outer muscular band to the base of the skull, attaching a short distance away from the midline. The rhomboid is not seen under the trapezius as a distinct form, but rather adds a muscular fullness to the back of the neck in front of the shoulder.

Spinal Muscles

The spinal muscles are a complicated group of muscles that pass along the back of the animal from the pelvis to the middle of the neck. Each muscle consists of numerous overlapping bundles that continuously originate and insert along the spine. They lie on either side of the upper surface of the vertebral column, separated by the upright spines. This powerful muscle group consists of four units: the longissimus, the ilio-costalis, the spinalis & semispinalis, and the multifidus, all of which may be divided into regional components (cervicis, thoracis & lumborum). The longissimus, iliocostalis and spinalis comprise the erector spinae (sacrospinalis). The longissimus capitis (to the head) and longissimus atlantis (to the first neck vertebra) are described with the neck muscles.

• Action: They primarily extend the vertebral column. Their contraction will also fix the spine into a rigid column. A muscle contracting on one side only will bend the spine toward that side. Some units also pull the ribs rearward, which assists in breathing.

HORSE AND OX

Longissimus (cervicis, thoracis & lumborum)

• Origin: Deep surface of the front of the pelvis from its inner to its outer expansions, and the upper bony projections of the thoracic and lumbar vertebrae and front half of the sacrum.

• Insertion: Sides of the thoracic and lumbar vertebrae, the upper ends of all the ribs except the first, and the sides and tops of the last four neck vertebrae (fourth through the seventh).

• Structure: The longissimus is the longest and largest muscle in the body. The thick lumbar portion is called the "common mass." A depression in its upper surface, just to the front of the pelvis, gives origin to the gluteus medius muscle. This depression in the ox is smaller and doesn't advance as far forward as in the horse. At the middle of the trunk, the longissimus divides into upper and lower portions, both of which insert into the last four neck vertebrae. The upper portion, the spinalis & semispinalis, inserts into their upper spines, and the lower portion, a continuation of the longissimus, attaches to their side projections. The overall mass is usually slighter in the ox, especially the cow, allowing the bony projections of the vertebral column and the pelvis to be conspicuous.

iliocostalis (thoracis & lumborum)

• Origin: Fascia covering the longissimus, beginning deep at the level of the fourth lumbar vertebra, and the upper ends of the last fifteen ribs. Ox: Also from the crest of the pelvis and the sides of the lumbar vertebrae.

• Insertion: Upper ends of all the ribs, and the side of the last (seventh) neck vertebra.

• Structure: This narrow, flattened, thin muscle lies on the surface of the upper portion of the rib cage. Emerging from under the longissimus between the last rib and the pelvis, it passes forward along the outer edge of the longissimus.

Multifidus

• Structure: The multifidus, extending along the entire spine as a continuous series of small overlapping bundles, lies on the sides of the upwardly projecting spines of the vertebrae. It does not come to the surface as it is covered by the longissimus.

DOG AND FELINE

Longissimus (cervicis, thoracis & lumborum)

• Origin: Inner (deep) surface of the wing (ilium) of the pelvis and its crest, and the upper bony projections (spinous processes) of the lumbar vertebrae.

• Insertion: Sides of all the lumbar and thoracic vertebrae, the upper ends of all the ribs, and the side of the sixth neck vertebra.

• Structure: This is the largest of the spinal muscles, and along with the iliocostalis, forms a very thick, columnar muscle mass in the lumbar region. In the feline, the lumbar portion of the longissimus is not covered by the iliocostalis, which begins from a more forward position.

Iliocostalis (thoracis & lumborum)

• Origin: Inner surface of the wing of the pelvis and its crest, the sides of the lumbar vertebrae, and the upper ends of the ribs.

• Insertion: Upper ends of the ribs, and the side of the last (seventh) neck vertebra.

• Structure: Outermost of the spinal muscles, the iliocostalis passes from the pelvis to the base of the neck. In the feline, this muscle is thinner than in the dog and begins at the rear end of the rib cage, not at the pelvis.

Spinalis & Semispinalis (thoracis)

• Origin: Surface of the longissimus dorsi toward the rear of the rib cage (from the level of the seventh to the eleventh thoracic vertebrae).

• Insertion: Upward projections on the tops of the sixth neck vertebra to the sixth thoracic vertebra.

• Structure: The muscle mass of the spinalis & semispinalis sits above the longissimus, toward the midline of the back. Not directly seen on the surface, it adds a muscular fullness to the back before diving under the shoulder blade.

Multifidus (thoracis & lumborum)

• Origin: Various places on the sides of the vertebrae, from the third thoracic vertebra to the first tail vertebra.

• Insertion: Spinous processes of the seventh neck vertebra to the sixth lumbar vertebra.

• Structure: Lying in contact with the upright spines of the vertebrae, the multifidus comes to the surface on the middle of the back, especially in the lumbar region, where it is thickest. It is made up of numerous small bundles that begin on the side of one vertebra, pass forward over one or two vertebrae, and insert on the top of the next vertebra.

depression for gluteus medius sacrum

LONG ISS! MUS

spinalis « semispinals iliocostals a

ILIOCOSTALIS

Sacral Ligament Cattle

depression for gluteus medius sacrum a

ILIOCOSTALIS

LONG ISS! MUS

spinalis « semispinals iliocostals

Cows Gluteus MuscleInfraspinatus Animal

C Cervical vertebra; I lliocostalis; Lo Longissimus; L Lumbar vertebra; M Muttifidus; S Spinalis 8 Semispinolis; T Thoracic vertebra.

HORSE

Horse Abdomen Anatomy

HORSE

Internal abdominal oblique (Obliquus internus abdominis)

HORSE

• Origin: Outer expansion of the front of the pelvis ("point of the hip")

• Insertion: Inner surface of the cartilage of the last four or five ribs, and by its wide tendon, into the midline on the bottom of the abdomen (linea alba) and the front end of the bottom of the pelvis.

• Action: Compresses the abdomen and supports its contents; assists in bending the spine to one side.

• Structure: The internal abdominal oblique is a triangular, fan-shaped muscle that develops a large, wide tendon. The muscular portion is located on the upper portion of the side of the abdomen. The muscle and tendon of both sides of the body form a continuous sling that passes under the abdomen and passively supports the abdominal contents when relaxed, or compresses them when the muscle is tensed. The wide tendons from each side of the body fuse on the abdominal midline, contributing to the linea alba. The linea alba is a tendinous thickening of the midline of the abdomen that passes from the rear end of the sternum to the front of the bottom of the pelvis (pubic bone). It is formed primarily by the fusion of the wide tendons of this muscle and the external abdominal oblique.

• Origin: Also from the surface of the lumbar spinal muscle (longissimus).

• Insertion: Most of the rear edge of the last rib and its cartilage, and by its wide tendon into the midline on the bottom of the abdomen (linea alba) and the front end of the bottom of the pelvis.

• Structure: This muscle is irregular in shape rather than triangular. Muscle fibers descending downward and forward from the point of the hip form a raised relief, called the "cord of the flank." This ridge borders the rear side of a triangular depression, the "hollow of the flank." The lumbar spinal muscles border the top of the hollow, and the last rib defines its front border. The cord and the hollow are usually subtle or absent in the horse, but they can be quite prominent in the ox, with the cord separating into two or three separate forms radiating from the point of the hip. Muscle fibers of both the internal and external abdominal obliques are present in the hollow, filling the space between the rib cage and the pelvis. This distance is greater in the ox than in the horse.

DOG AND FELINE

• Origin: Side of the spinal muscle in the lumbar region; lower end of the crest of the ilium at the front of the pelvis.

• Insertion: Lower end of the last rib and the midline of the abdomen via the wide tendon.

• Structure: The internal abdominal oblique lies inconspicuously on the side of the abdomen, mostly under cover of the external abdominal oblique. It does not produce the cord of the flank or the hollow of the flank.

Abdominal Oblique Muscle Horse

HORSE

External abdominal oblique (Obliquus externus abdominis)

HORSE

• Origin: Rear edge of the outer surface of the last fourteen ribs, the fascia between the ribs, and the side of the surface of the spinal muscles in the lumbar region. The position of the origin gets progressively lower on each rib toward the front of the body.

• Insertion: The midline of the abdomen (linea alba), from the sternum to the front end of the bottom of the pelvis (pubic bone), and the outer expansion of the front end of the pelvis (point of the hip).

• Action: Compresses the abdomen; flexes the trunk (primarily at the lumbar vertebrae); one side only bends the trunk toward that side.

• Structure: The external abdominal oblique is a large muscle composed of a muscular band, that curves upward on the side of the body, and an extensive tendon. It embraces part of the side of the rib cage and the entire abdomen. The lower edge of the muscular portion curves upward toward the point of the hip. The front of the muscular portion forms four units whose ends alternate (interdigitate) with the forms of the serratus ventralis thoracis; the forms of both muscles are oriented in roughly the same direction. The remainder intersects with the forms of the ribs, where they meet at a wide angle. The location of the insertion of the muscular fibers into its wide tendon on the side of the abdomen may be seen on the surface, especially during exertion. The wide tendon of the external abdominal oblique fuses to the wide tendon of the underlying internal abdominal oblique; the combined tendon passes over the rectus abdominis muscle to reach the midline of the abdomen. The front portion of the muscular portion of the external abdominal oblique overlaps the flat belly of the rectus abdominis.

• Origin: Rear edge of the outer surface of the last eight ribs and the fascia between the ribs.

• Structure: The upper edge of the muscle in the lumbar region lies just below the level of the point of the hip, but its wide tendon reaches up to insert into it.

DOG AND FELINE

• Origin: Last nine or ten ribs, the fascia between the ribs, and the side of the surface of the spinal muscles in the lumbar region.

• Insertion: The midline of the abdomen (linea alba), from the sternum to the front end of the bottom of the pelvis (pubic bone), and from a short ligament passing upward and forward from the pubic bone.

• Structure: There is no insertion into the upper front end of the pelvis. In the dog, the tips of the originating fibers of the front portion of the muscle (on the side of the rib cage) are covered by the latissimus dorsi muscle. In the feline, the entire origin from all the ribs is covered.

HORSE

Rectus abdominis

HORSE

• Origin: Cartilage of the fourth to the ninth ribs and the adjacent area on the sternum.

• Insertion: Front end of the bottom of the pelvis (pubic bone).

• Action: Flexes the trunk, primarily in the lumbar region; compresses the abdomen.

• Structure: The rectus abdominis is a long, straplike muscle, lying on the bottom of the abdomen. Widest at its middle, it passes from the bottom of the rib cage to the bottom of the pelvis. Several tendinous bands are embedded across the belly, functionally separating it into a series of short muscular units, rather than one long muscle. The muscle bellies of both sides of the body are separated by a narrow, fibrous band called the linea alba, which is formed primarily by the fusion of the wide tendons of the abdominal muscles that pass over and under the rectus abdominis.

• Origin: Outer edge of the sternum, from the level of the third rib cartilage continuing rearward.

DOG AND FELINE

• Origin: Dog: First rib and its cartilage, and the sternum. Feline: Cartilage of the first and second ribs, and the sternum.

• Structure: The muscle belly is widest toward the front, more so in the dog than in the feline.

Serratus dorsalis caudalis

• Origin: Surface of the spinal muscle in the region of the middle of the back.

• Insertion: Upper ends of the last few ribs, ranging from the last four to nine ribs, depending on the species.

• Action: Pulls the ribs rearward, assisting in exhaling.

• Structure: The muscle is insignificant in its effect on the surface. It is included here because its rear portion lies just under the skin.

SEÄRATUS DORSALIS CAUDALIS

Linea Alba Abdomen Horse

LINEA ALBA

Serratus Thoracis Horse

SEÄRATUS DORSALIS CAUDALIS

LINEA ALBA

HORSE

Linea Alba Dogs

SERRATUS VENIR AL ts CERVICIS (Nttk portion)

SERRATUS VENT RAUS THORACIS (Chflt portion)

SERRATUS VENIR AL ts CERVICIS (Nttk portion)

SERRATUS VENT RAUS THORACIS (Chflt portion)

Serratus ventralis (cervicis & thoracis)

HORSE

• Origin: Neck portion: Sides of the third or fourth to the seventh neck vertebrae. Chest portion: Sides of the lower ends of the first eight or nine ribs.

• Insertion: Deep surface of the upper half of the bony shoulder blade, and a narrow strip of the adjacent cartilage.

• Action: Neck portion: Pulls the upper end of the shoulder blade forward; lifts the neck; bends the neck to one side. Chest portion: Pulls the upper end of the shoulder blade backward and downward, which can rotate the shoulder blade, advancing the shoulder joint. The chest portion on both sides of the body forms an interrupted sling, between the upper ends of both shoulder blades, which supports the body. Both sides together raise the chest.

• Structure: The serratus ventralis is divided into distinct neck and chest portions. The neck portion (serratus ventralis cervicis), divisible into several converging bundles, comes to the surface on the side of the neck between the trapezius and the brachiocephalicus. It is homologous to the levator scapulae in humans. The chest portion (serratus ventralis thoracis, serratus magnus) is a fan-shaped muscle connecting the upper end of the shoulder blade to the side of the rib cage. Its lower rear por tion becomes superficial where it emerges from under the latissimus dorsi. The muscular bulk of the chest portion can be seen under the latissimus, to the rear of the triceps muscle. The pointed tips of the last four segments alternate (interdigitate) with the originating ends of the segments of the external abdominal oblique, giving the lower border of the serratus a saw-like "serrated" edge.

• Structure: The neck portion is covered by a layer of muscle. The chest portion projects beyond the lower edge of the latissimus dorsi. The pectoralis ascendens covers the lower ends of the forward segments of the chest portion.

DOG AND FELINE

• Structure: The entire serratus ventralis is covered by other muscles. The chest portion, covered by the latissimus dorsi, adds a muscular fullness on the side of the rib cage to the rear of the shoulder blade. It also conceals the forms of the underlying individual ribs. Those ribs covered only by the latissimus may often be seen on the surface. The attachments are very similar to those of the horse.

nuchal ligament

TRAPEZIUS Neck portion Tfcnradc portion

HORSE

nuchal ligament

TRAPEZIUS Neck portion Tfcnradc portion

HORSE

Nuchal Ligament Bovine

Trapezius HORSE

• Origin: Single, continuous line of origin on the midline of the back of the neck and chest for the entire muscle. Neck portion: On the nuchal ligament from the level of the second neck vertebra to the top of the shoulder. Thoracic portion: Along the tips of the thoracic vertebrae and intervening ligament from the shoulder to the middle of the chest.

• Insertion: Neck portion: Entire elongated raised ridge (spine) of the shoulder blade. Thoracic portion: Bony expansion one third of the way down the spine of the shoulder blade.

• Action: Entire muscle pulls the shoulder blade upward; it can also hold the shoulder blade against the body. The neck portion pulls it upward and forward; the thoracic portion pulls it upward and rearward.

• Structure: The trapezius is a large, flat, thin, triangular muscle that is further divided into two smaller triangles by an intervening narrow tendinous area. The front triangle defines the neck portion and the rear triangle the thoracic portion. The entire length of the originating end of the muscle begins as a tendinous band before becoming a muscular sheet. The thoracic portion becomes tendinous again before inserting into the expansion of the spine. The larger neck portion inserts lower down on the spine of the shoulder blade than the thoracic portion. The trapezius is usually not seen defined on the surface, allowing the underlying structures to be seen through its thin layer. The lower edge of the thoracic portion may occasionally be seen directly.

• Structure: The trapezius is thicker in the ox, and begins on the neck closer to the base of the skull than in the horse. The two portions are also less distinct. The upper part of the front edge is in contact with the brachiocephalicus, closing up the interval present in the horse, which allows deeper neck muscles to come to the surface.

DOG AND FELINE

• Origin: Midline of the lower portion of the back of the neck and the front portion of the thorax, from the third neck vertebra to the ninth thoracic vertebra in the dog, and from the second neck vertebra to the twelfth thoracic vertebra in the feline.

• Insertion: Neck portion: Upper three-fourths of the spine of the shoulder blade. Thoracic portion: Dog: Upper one third of the spine; Feline: Bony expansion one third of the way down the spine.

• Structure: The trapezius is thicker in the dog and the feline than in the horse; more so in the feline. The thoracic portion is thicker than the neck portion.

HORSE

Latissimus dorsi HORSE

• Origin: Surface of the spinal muscles from the top of the shoulder through the lumbar region (ultimately from the tips of the vertebrae in this region).

• Insertion: Inner surface of the humerus, slightly less than halfway down the bone, in common with the teres major.

• Action: Flexes the shoulder joint, pulling the humerus upward and back; pulls the body forward when the front limb is advanced and set firmly on the ground.

• Structure: The latissimus dorsi is a large, thin, triangular muscle that lies on the side of the chest. Because it is relatively thin, it allows the mass of the serratus ventralis and the forms of the individual ribs to be seen underneath. The diagonal lower edge of the muscle is often quite conspicuous in life as it passes over the ribs and then over the segments of the serratus ventralis (thoracis). The latissimus begins as a wide tendon fused to the fascia of the spinal muscles. The front free edge of the muscle emerges from under the trapezius and then passes over the upper rear corner of the shoulder blade (and over the infraspinatus). The latissimus narrows and thickens on its way to its insertion, and then disappears as it dives deep to the tensor fasciae antebrachii and triceps.

• Origin: Also from the sides of ribs nine through twelve.

• Structure: The latissimus covers a larger surface area than in the horse.

DOG AND FELINE

• Origin: Dog only: Also from the last two or three ribs.

• Insertion: Inner surface of the humerus, approximately one third of the way down the bone, in common with the teres major. Also, into a tendinous arch that begins at the previous insertion, arches over the biceps, and expands to attach to the inner front corner of the upper half of the humerus. Because the lower extent of this arch ends approximately halfway down the humerus (further down in the feline), the lower edge of the latissimus, which can be visible on the surface, is seen to be directed much lower on the humerus than the bony insertion one third of the way down the humerus.

• Structure: The inserting end (front end) of the muscle is wider than in the horse (it tapers less), which brings the lower edge of the latissimus closer to the bottom of the chest before it passes under the triceps.

Latissimus Dorsi

latissimus DORSI

umnn

Latissimus Dorsi Dog

LATISSIMUS DORSI

PECTORALIS TRANSVERSUS

SERRATUS VENTRALIS THORACIS

PECTORALIS ASCENDENS

EXTERNAL ABDOMINAL OBLIQUE

Cat Muscle Diagram Serratus Ventralis

Pectoralis muscle group

The pectoralis muscle group consists basically of two major layers of muscle—the superficial pectorals (pectoralis descendens and pectoralis transversus in the horse, the ox, and the dog, plus the pectoan-tibrachialis in the feline) and the deep pectorals (subclavius and pectoralis ascendens in the horse and the ox; pectoralis profundus in the dog, and pectoralis profundus and xiphihumeralis in the feline). The superficial pectorals are homologous to the pectoralis major in humans, whereas the deep pectoral is represented by the human pectoralis minor. In animals, the pectorals are sometimes also called pectoralis major and minor. In the horse and the ox, the superficial and deep layers each have an anterior (front) portion and a posterior (rear) portion.

Pectoralis descendens

HORSE AND OX (Anterior superficial pectoral)

• Origin: Line on the front edge of the cartilage at the front end of the sternum (except the front tip), continuing back to the level of the second rib.

• Insertion: Diagonal line, inclined downward and inward, on the front of the lower half of the humerus, and the adjacent outer surface of the muscles of the limb.

• Action: Pulls the front limb toward the centerline of the body; advances the front limb.

• Structure: In the horse, the pectoralis descendens forms a thick, conspicuous, oval form on the front of the chest between the sternum and the lower end of the upper arm. It passes over the biceps to insert between the biceps and the brachialis. The bulging muscles of both sides of the body create a furrow on the midline of the chest at the bottom of which lies the sternum. The rear edge of the muscle overlaps the pectoralis transversus. In the ox, this muscle is thin and closely attached to the pectoralis transversus, which it overlaps.

DOG AND FELINE

• Origin: Front end of the sternum. Feline: Also from a tendinous line on the midline of the base of the neck in front of the tip of the sternum.

• Insertion: Short vertical line on the middle of the front of the humerus.

• Structure: The pectoralis descendens lies diagonally on top of the pectoralis transversus. It passes over the biceps and under the brachiocephalicus to insert on the humerus between the biceps and the brachialis.

In the feline, there is an additional superficial muscle, the pectoantibrachialis (see page 61), that lies on top of the two superficial pectorals. This narrow muscle originates on the sternum a short distance back from its tip and eventually tapers into a flat, thin tendon that passes over the forearm flexor muscles (on the inside of the elbow) before inserting into the ulna a short distance below the tip of the elbow. It lies alongside the edge of the brachiocephalicus.

BRACHIOCEPHALICUS PECTORALIS DESCENDENS

STERNOMANDIBULARIS

HORSE

Sternomandibularis CattleMuscles Equine Forearm

PECTORALIS DESCENDENS

PECTORALIS TRANSVERSUS

SERRATUS VENTRALIS THORACIS

PECTORALIS ASCENDENS

EXTERNAL ABDOMINAL OBLIQUE

BRACHIOCEPHALICUS PECTORALIS DESCENDENS

PECTORALIS DESCENDENS

STERNOMANDIBULARIS

HORSE

HORSE

Muscles Equine Forearm

PEC TOR AllS TRANSVERSAS

HORSE

PEC TOR AllS TRANSVERSAS

Muscles Equine Forearm

PECTORAL IS TRANSVERSUS

Serratus Thoracis HorseFlexor Rectangular Muscle

BOTTOM VIEWS

Pectoralis transversus

HORSE AND OX (Posterior superficial pectoral)

• Origin: Lower edge of the sternum, from the second to the sixth rib, and from an overlying fibrous partition on the midline of the chest (from which the muscles of both sides originate).

• Insertion: Primarily into the inner surface of the upper third of the forearm muscles. In the horse, a small portion at the front end of the muscle inserts directly into the front of the lower end of the humerus.

• Action: Pulls the front limb toward the centerline of the body.

• Structure: The pectoralis transversus is a rectangular muscular sheet sitting on the bottom of the chest, passing from the sternum to the inside of the elbow region and the upper end of the forearm. Its front edge is overlapped by the pectoralis descendens. This is a thin muscle in the ox. DOG AND FELINE

• Origin: Front portion of the sternum, to the level of the fourth rib.

• Insertion: Line running down most of the front of the humerus.

• Structure: The pectoralis transversus is a flat, rectangular muscle that passes from the midline of the chest to the shaft of the humerus. Along with the pectoralis descendens (which lies on top of it in the dog), it passes over the biceps and under the brachiocephalicus to insert on the humerus between the biceps and the brachialis.

Subclavius Muscle Horses

Subclavius (Anterior deep pectoral)

HORSE

• Origin: Cartilages of the first four ribs and the adjacent sternum (exclusive of the front edge of the sternum and its front tip).

• Insertion: Upper front surface of the supraspinatus muscle, toward its inner side; there is no bony insertion.

• Action: Pulls the limb toward the centerline of the body; pulls the shoulder blade, and therefore the limb, backward. When the limb is advanced forward and set firmly on the ground, the subclavius pulls the body forward.

• Structure: The subclavius is a thick, powerful muscle that begins on the side of the chest and ends on the front of the shoulder. It passes upward, forward, and outward, then curves backward, ending on the surface of the supraspinatus. The center section of the upper portion is not covered by other muscle. It creates the forwardmost convex form of the shoulder muscles, which can be quite visible on the side of the base of the neck.

• Origin: Cartilage and lower end of the first rib.

• Insertion: Deep surface of the brachiocephalicus, in the region of the front of the upper end of the humerus.

• Structure: The subclavius is a small, deep muscle not seen on the surface. It does not extend onto the surface of the supraspinatus, as in the horse.

The subclavius is not present in the dog or the feline.

Anatomy The Subclavius

HORSE

PECrORAtIS ASCENDENS

HORSE

PECrORAtIS ASCENDENS

Pectoral Attachments Dog

ttrrsiOE views t FRONT

PECTORAL IS PROFUNDUS

ttrrsiOE views t FRONT

PECTORAL IS PROFUNDUS

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Responses

  • Darren
    What structures are in the jugular furrow of a cow?
    8 years ago
  • sophia
    What are the two bulging muscles on the surface of the mylohyoid?
    8 years ago
  • Raymond tang
    Hi<br /><br />Let me know if there is any special way to improve horse serratus muscle by training <br /><br />Thanks<br /><br />Raymond
    8 years ago
  • ninfa
    What is linea alba of cow?
    4 years ago
  • Simon Eyob
    What are superficial and deep part recuts abdomens in anima cow?
    3 years ago
  • jan keller
    What is Linea alba of animal?
    3 years ago
  • jesse
    How to improve sternocephalicus?
    7 months ago
  • roy
    Where does the mylohyoid originate from dogs?
    14 days ago

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