LATERAL SUPERFICIAL MUSCLES

Transcription

1 LATERAL SUPERFICIAL MUSCLES trapezius cervicis splenius trapezius thoracis serratus dorsalis caudalis temporalis latissimus dorsi thoracolumbar fascia tensor fascia latae intercostales gluteus superficialis biceps femoris (vertebral segment) masseter sternomandibular semitendinosus brachiocephalicus deltoideus triceps brachii long head triceps brachii lateral head brachialis (insertion) extensor carpi radialis extensor digitorum communis extensor digitorum lateralis biceps femoris (ischial segments) pectoralis ascendens flexor carpi ulnaris flexor carpi radialis ulnaris lateralis obliquus externus abdominis flexor digitorum profundus extensor digitorum lateralis extensor digitorum longus

2 Temporalis Origin: The muscle begins at the facial crest and zygomatic arch Insertion: It terminates on the lateral surface of the ramus of the mandible Function: When active it closes the jaw Physical Reaction: The horse will pull their head away when touched, and may show aggravation or tenderness at the temporomandibular joint. Reluctant to chew on affected side, uncomfortable to open mouth and grinding of teeth. Latissimus Dorsi Origin: From the Lumbodorsal fascia from the highest point of the withers to the beginning of the lumbar region. Insertion: Inserts on the Teres tuberosity on the medial surface of the humerus Function: Flexes the shoulder joint and retracts the forelimb. If the leg is fixed it draws the trunk forward, and bends the spine laterally. Physical Reaction: If sensitive, horse will bend laterally to the shortened side and may not want to extend the forelimb. Slenius Cervicis Origin: Arises with the Slenius Capitis from T-3/T-5 via the thoracolumbar fascia and the nuchal ligament Insertion: Transverse Process of C3-C5 Function: Elevates the neck when both sides are active. When only one side is engaged it bends the neck laterally toward the side of contraction. Physical Reaction: The horse will bend to the side of functional shortening. Intercostales (Internal and External) Origin: The intercostales arise from the cranial borders of the ribs and cartilage, the external intercostales come from the caudal borders of the ribs. Insertion: The internal muscles end on the caudal boarders and lateral surface of the cartilage. The external intercostals end on the cranial boarders and lateral surfaces of succeeding ribs. Function: Support the rib cage and help breathing. The internal muscles exhale and the external muscles inhale Physical Reaction: Flinching and moving away when pressure is applied. If a horse has tied up or had colic recently the area may be very sensitive throughout the entire region. Trapezius Cervicis Origin: The funicular portion of the nuchal ligament from C2-T3 Insertion: Ends on the free edge of the scapular spine over its entire length, blending with the shoulder and arm fascia. Function: Draws the scapula cranially and dorsally and elevates the shoulder. Physical Reaction: Flinching, stomping, moving away when pressure is applied behind the scapula, and the shoulder may be higher and more upright on the shortened side. Trapezius Thoracis Origin: Arises from the supraspinous ligament from T3-T10. Insertion: Ends on the caudal portion of the tuberosity of the scapular spine. Function: Draws the scapula caudally and dorsally elevating the shoulder. Physical Reaction: Flinching, stomping, moving away when pressure is applied behind the scapula, and the shoulder may be higher and more upright on the shortened side. This muscle can also be sensitive if there has been a lower leg issue. Serratus dorsalis caudalis Origin: Arises from the thoracolumbar fascia Insertion: The segments end on the lateral surface of the last 7 or 8 ribs Function: Draw the ribs caudally and assist in breathing Physical Reaction: Draws the ribs caudally and helps aid breathing, and if sensitive the horse may object to touch and a saddle. Tensor fascia latae Origin: Starts on the cranioventral aspect of the tuber coxae and the adjacent lateral margin o the ilium Insertion: Ends on the fascia lata which surrounds the lateral aspect of the quadriceps and stifle joint. The fasia is attached to the patellar ligaments, tibial crest and 3rd trochanter. Function: Flexes the hip and extends the stifle Physical Reaction: Tighting of muscle, kicking to the side, moving away from pressure, when the horse is moving forward there may be excessive abduction with the foot landing outside the track, find crossing over the hind feet difficult, may move on 3 tracks or step in.

3 Gluteus superficialis Origin: Starts on the gluteal fascia, tuber coxae and lteral border of the ilium. Insertion: Third trochanter of the femur Function: Flexes the hip joint, rotates, protracts and abducts the hindlimb Physical Reaction: When sensitive the horse may swing the hindlimb outward and rotate the hoof internally, crossing over behind may be difficult- may object to a half pass or side steps. Biceps femoris (vertebral segment) Origin: The vertebral head extends as far forward as the SI joint, arising from the SI ligament, the caudal margin of the ilium, the ischiatic head arises from the tuber ischia via a strong tendon Insertion: The caudal aspect of the femur, the cranial surface of the patella and the lateral patellar ligament Function: retraction of the hindlimb Physical Reaction: If sensitive or shortened the horse will tuck under dramatically with light to medium pressure, and the tissue at the vertebral origin will feel knotted. If you push on the ischial head the horse may kick, and they will object to flexing the hip and stifle as the limb moves forward, or find it difficult to lower the hind end for collected maneuvers, and have a catch in the breakover. Semitendinosus Origin: The vertebral head(long head) can extend as far forward as the last sacral vertebra, but typically comes from the transverse process s of the first two caudal vertebrae. The short ischiatic head originates from the ventral surface of the tuber ischii. Insertion: Some of this muscle inserts on the cranial margin of the tibia, while the larger part blends with the fascia of the leg( crural fascia) and the remainder unites with the biceps femoris tendon running of the calcaneal tuberosity. Function: When active it extends the hip and hock joints. It adducts and retracts the hindlimb. Physical Reaction: The horse will tighten the leg, step towards you or tuck under when palpating the area with pressure. The cranial phase of stride will be restricted and shortened and may find it difficult to collect the hind end. Flexor Digitorum Profundus (hindlimb)(deep Digital Flexor Muscle) Origin: This muscle has three heads; medial, lateral, and caudal. The lateral head lies on the caudal surface of the tibia and comes from the lateral condyle of the tibia and the adjacent part of the fibula. The caudal head lies behind the lateral head and is attached to it. It comes from the lateral condyle of the tibia and the head of the fibula. The tendons of the lateral caudal heads fuse to form a single tendon running through the tarsal groove on the caudal surface of the hock. The medial head(long digital flexor) comes from the lateral tibia condyle and crosses the caudal surface of the tibia obliquely in the groove between the popliteus and the caudal head. It is thin and easily separated from the related muscles. It gives rise to a thin tendon that passes over the medial surface of the hock before joining the main tendon about a third of the way down the metatarsus. Insertion: The muscle ends on the semilunar line of the distal phalanx and the boarding cartilage. Function: Extend the hock and flex the digit. Physical Reaction: The horse will pull the leg up and try to move away, and the muscle and tendon are more susceptible to injury in low heel, long toe conformation. The toe may tend to point to the ground longer and you are able to see the sole of the hoof longer as compared to the other hoof. Extensor Digitorum Lateralis (hind limb) Origin: Begins on the lateral collateral ligament of the stifle joint, the fibula, and lateral marging of the tibia. Insertion: Ends on the tendon of the extensor digitorum longus about a third of the way down the metatarsus. Function: Tuning the configuration of the leg rather than providing any propulsion, and may assist the extensor digitorum longus in stabilizing the stifle joint. Physical Reaction: The leg could spasm or kick out. This muscle may have been involved in a stifle injury or due to the realationship to the stifles lateral collateral ligament.

4 Extensor Digitorum Longus (hind limb) Origin: Begins on the extensor fossa of the femur. Insertion: Ends on the extensor process of the distal phalanx as well as the dorsal surface s at the proximal edges of the proximal and middle phalanges. Function: Extends the digital joints, assists in flexing the hock and fixing the stifle joint. Dorsal branches of interosseous muscle ( suspensory ligament) guard against the knuckling over as the hoof is swung forward. Physical Reaction: The leg could spasm or kick out. This muscle could be involved in a stifle injury or irregularity, and flexion of the digit may be restricted if this muscle is shortened. Obliquus Externus Abdominis Origin: This muscle starts at T4 on the lateral surface of the ribs and the fascia covering ther external intercostal muscles, and continues to the thoracolumbar fascia. Insertion: The long area of insertion includes the linea alba and the prepubic tendon, the body of the ilium and the tuber coxae and incorporates the medial femoral fascia. Function: When active it compresses the abdominal viscera and aids in defecation, birthing, and exhaling. When both sides are contracted it arches the back and when only one side is active it flexes the trunk laterally. Physical Reaction: Horse may be unwilling to work off the riders leg, kicking out when the rider uses the leg, defensive to touch in the area and acting girthy. When the muscle is shortened it may be difficult for the horse to bend toward the affected side, especially in any collected pose. Pectoralis Ascendens Origin: Comes from the ventral surface of the sternum, xiphoid cartilages, adjacenet costal cartilages of ribs 4-9 and the abdominal tunic. Insertion: Arises from the cranial part of the medial tuberosity of the humerus just below the medial insertion of the supraspinatus. Function: When the limb is raised it is retracted and adducted. If the limb is fixed the trunk is drawn forward. Physical Reaction: The horse may pull up when touched and resist a girth being tightened, and the foreward stride will be shortened and the hoof will land inside the track. Flexor Carpi Ulnaris Origin: 1. The medial epicondyle of the humerus caudal to he origin of the flexor carpi radialis. 2. Medial surface and caudal boarder of the olecranon. Insertion: Proximal edge of the accessory carpal bone. Function: Flexes the carpal joint and extends the elbow Physical Reaction: While in motion the cranial phase may be shortened and have less extension of the carpal joint. Flexor Carpi Radialis Origin: Beings on the medial epicondyle of the humerus, distal and caudal to the medial collateral ligament. Insertion: The proximal end of the second metacarpal bone. Function: Flexes the carpal joint and assists extending the elbow. Physical Reaction: While in motion the cranial phase may be shortened and have less extension of the carpal joint. Extensor Digitorum Lateralis(Forelimb) Origin: Arises from the distal end of the lateral collateral ligament of the elbow joint and adjacent bone, the body of the ulna and the lateral border of the radius. Insertion: Terminates on the dorsal aspect of the proximal extremity of the proximal phalanx lateral to the tendon of the common extensor. Function: Extends the carpus and digit. Physical Reaction: Horse may resist flexing of the forelimb. Extensor Digitorum Communis Origin: There are several heads and origins. 1. Humeral head: the cranial edge of the distal extremity of the humerus beneath the origin of the extensor carpi radialis. 2. Radial head: lateral proximal portion, lateral collateral ligament of elbow, and lateral border of the radius at the junction of proximal and middle thirds. 3. Body of ulna, lateral surface. 4. Fascia of forearm. Insertion: 1. Extensor process of the distal phalanx (coffin bone). 2.Proximal and middle phalanges via the lateral digital extensor. Function: When active, it extends the digital and carpal joints and assists in flexing and stabilizing the elbow joint. Physical Reaction: If this muscle is tight, the horse will resist bending the carpus and the fetlock.

5 Extensor Carpi Radialis Origin: This muscle begins at the lateral epicondyle and the supraepicondyloid crest. Insertion: The tendon crosses the carpal joint and inserts on the metacarpal tuberosity. This is a roughened area at the proximal end of the third metacarpal (cannon) bone on its dorsolateral surface. Function: When active it extends the carpal joint and assists in flexing the elbow joint. Physical Reaction: The horse may repeatedly pull the leg away when palpating the tendon or the muscle belly. The horse may object to flexing the carpus when the muscle is functionally shortened. The elevation of the carpal joints may appear asymmetrical with reduced carpal flexion. Brachialis Origin: This muscle begins at the caudal surface of the humerus at its proximal end. Insertion: It ends on the craniomedial aspect of the head of the radius beneath the long collateral ligament of the elbow joint. Function: When active it flexes the elbow joint. Physical Reaction: This muscle begins as a deep muscle then becomes superficial at its insertion. You can only access this superficially at its insertion dorsal and cranial to the extensor carpi radialis. Extension of the elbow is limited when the brachialis is physically shortened. The horse may snap up the leg more quickly after loading in the retraction phase of the limb. Triceps Brachii : lateral head Origin: This muscle begins on the curved roughened line (the tricipital line) running from the lateral aspect of the head of the humerus to the deltoid tuberosity. Insertion: The muscle ends on the lateral surface of the proximal tuberosity of the olecranon. Function: When active it extends the elbow joint. Physical Reaction: The horse may be reluctant to finish loading the suspect limb with pressure anywhere on this muscle. Flexion of the elbow may be restricted if this muscle is shortened. Similar issues also found in the medial head of the triceps brachii may be noted or observed. Triceps Brachii : long head Origin: The long head of the triceps brachii muscle originates from the caudal border of scapula. Insertion: The tendon of insertion ends on the proximal tuberosity of the olecranon (point of the elbow). Function: The long head of this muscle flexes the shoulder joint and extends the elbow joint. Physical Reaction: If positive the horse may pick up the leg or show signs of aggravation. If shortened, extension of the shoulder joint and the forelimb is limited. In this cranial phase, the horse may look irregular or uneven in extended gaits. Deltoideus Origin: This muscle begins on the spine of the scapula via the aponeurosis covering the infraspinatus. It also includes a small area of the scapula near its caudal angle and just cranial to the origin of the teres major. Insertion: It terminates on the deltoid tuberosity and the bony ridge running proximally from it towards the greater tubercle, the related fascia of the arm. Function: When active it flexes the shoulder joint. It also provides lateral rotation and abduction of the arm. Physical Reaction: The horse may be irritated or sensitive to touch along the caudal portion of the scapular spine and caudal border of the scapular body. The horse may flex the limb and bring it closer to the trunk. The horse will be reluctant to cross medially with the forelimb. Extending the shoulder joint may prove difficult. Brachiocephalicus Origin: This muscle begins on the mastoid process and the nuchal crest of the skull. Insertion: This muscle ends on the deltoid tuberosity and the Function: When active it protracts limb and is a prime limb mover when head and neck are fixed. When one side is contracted this muscle bends the neck laterally to the shortened side. Physical Reaction: Sometimes issues here will feel like a bunching of tissue around the fifth cervical vertebra and the horse will respond as if "nervy" with a light to medium palpation. The horse may be fine in straight line but off in front on the circle. The horse tends to snap up the affected forelimb faster. Gaited horses will appear quite irregular when this muscle is an issue. This muscle will appear as a compensatory issue when there are distal limb issues.

6 Sternomandibular Origin: This muscle begins at the cranial end of the stern um. This portion of the sternum is cartilagenous and is known as the manubrium. Insertion: This muscle ends on the caudal edge of mandibular ramus. Function: When both sides are active, it flexes the head and neck. When only one side is active, it inclines the head and neck towards the contracted side. Physical Reaction: The horse will stomp or move away, or toss the head and neck with even a light pressure. Girthing problems are sometimes associated with this stress area as well as the multifidi muscles at the cervicothoracic vertebral junction along with the ascending pectorals.