Musculoskeletal System

Skeletal muscle

Striated, voluntary muscle; can also be cruise controlled (e.g. breathing, swallowing)

Cardiac muscle

Striated, involuntary muscle; contracts rhythmically, adopt the contraction rate of the most rapid cell

Smooth muscle

Nonstriated, involuntary muscle; forms of this muscle include visceral and multiunit

Visceral smooth muscle

Large sheet organ walls made of cells (wall the stomach, intestine, uterus, bladder, blood vessels, respiration); responds to the stretching of the lumen; reacts in rhythmic waves

Multiunit smooth muscle

Small and delicate movements are required for this muscle; examples include the iris, ciliary body of the eye, small blood vessels and small air passages; require specific impulses from the nervous system to contract (e.g. light changes)

Aponeuroses

Connect muscle to bone or to another muscle

Primary mover (agonist)

Muscle group that directly produces a desired movement

Antagonist

Directly opposes the action of a muscle group

Synergist

Muscles that contracts at the same time as a prime mover and assists in the action

Fixator

Stabilize joints to allow other movements to take place

Extension

Act of not being bent

Flexion

Act of being bent

Flexor surface

Decreases the resting angle of a muscle

Extensor surface

Increases the resting angle of a muscle

Extrinsic muscles

Muscles that attach the limb to the body; originates outside the structure it moves and inserts itself into it

Superficial pectoral

Pectoralis major

Craniolateral

The descending portion of the superficial pectorial that arise from the first two sternebrae and runs in a _____ direction

Transversely

The transverse portion of the superficial pectorial that originates from first three sternebrae and runs…

Sternum (cranial sternum)

Superficial and deep pectoral origin

Humerus (great tubercle)

Superficial and deep pectoral insertion

Adducts thoracic limb

Superficial and deep pectoral action

Deep pectoral

Pectoralis minor

Trapezius

Thin triangular muscle that lies over the dorsal part of the scapula; divided into cervical and thoracic portions

Neck and thoracic vertebrae (dorsal aspect)

Trapezius origin

Scapular spine

Trapezius insertion

Elevates and abducts the forelimb

Trapezius action

Latissimus Dorsi

Large triangular shaped muscle lies caudal to the scapula and covers much of the thoracic wall

Draws thoracic limb caudally and flexes shoulder joint

Latissimus Dorsi action

Cervical vertebrae

Serratus Ventralis (cervical) origin

Ribs

Serratus Ventralis (thoracic) origin

Scapula (serrated face)

Serratus Ventralis insertion

Supports the trunk and depresses the scapula

Serratus Ventralis action

Intrinsic muscle

Muscle that attaches to the bones within the limb; have both their origin and insertion entirely within the specific body region they move

Infraspinatus

Muscle fills the infraspinous fossa caudal to the spine of the scapula

Infraspinous fossa (scapula)

Infraspinatus origin

Humerus (greater tubercle)

Infraspinatus insertion

Flexes the shoulder joint and abducts shoulder limb

Infraspinatus action

Supraspinatus

Fills the supraspinous fossa cranial to the spine of the scapula, wider and longer than its counterpart

Supraspinous fossa (scapula)

Supraspinatus origin

Humerus (greater tubercle)

Supraspinatus insertion

Extends glenohumeral joint

Supraspinatus action

Subscapularis

Muscle occupies the subscapular fossa on the medial aspect of the scapula

Subscapular fossa (scapula)

Subscapularis origin

Humerus (lesser tubercle)

Subscapularis insertion

Adducts shoulder limb and rotates forelimb medially

Subscapularis action

Biceps Brachii

Located on the craniomedial aspect of the humerus; only has one head in domestic animals

Scapula (supraglenoid tubercle)

Biceps Brachii origin

Ulna and radius (proximal)

Biceps Brachii insertion

Flexes the elbow and extends the shoulder

Biceps Brachii action

Triceps brachii

Antagonist of the biceps brachii

Supraspinatus

Synergist of the biceps brachii

Triceps Brachii

Makes up the large muscle mass on the caudal aspect of the humerus; commonly has 3 heads, but carnivores have a fourth head (long, medial, lateral, accessory)

Scapula (caudal border) and humerus (proximal border)

Triceps Brachii origin

Ulna (olecranon)

Triceps Brachii insertion

Extends the elbow and flexes the shoulder

Triceps Brachii action

Extensor reticulum

Thick fascial band, near carpal joint; holds the tendons of these muscles in place

Extensor Carpi Radialis

Largest craniolateral muscle of the antebrachium

Humerus (distal)

Extensor Carpi Radialis origin

Metacarpals (proximal aspect II and III)

Extensor Carpi Radialis insertion

Extends the carpus

Extensor Carpi Radialis action

Common Digital Extensor

Lies caudal to the extensor carpi radialis on the lateral side of the forelimb; tendon of insertion branches into four separate branches and each inserts on the dorsal surface of the proximal phalanges of the major digits; craniolateral muscle of the antebrachium

Humerus (lateral epicondyle)

Common Digital Extensor origin

Digits II-V (dorsal surface)

Common Digital Extensor insertion

Extends the carpus and digits

Common Digital Extensor action

Superficial Digital Flexor (SDF)(thoracic)

Lies caudomedial to the ulna; tendon of insertion divides into four major branches and each branch inserts on one digit

Humerus (medial epicondyle)

Superficial Digital Flexor (thoracic) origin

Digits II-V (middle phalanx)

Superficial Digital Flexor (thoracic) insertion

Flexes the carpal and digital joints

Superficial Digital Flexor (thoracic) action

Deep Digital Flexor (DDF)(thoracic)

Muscle has 3 heads of origin (humeral, ulnar, and radial); tendons of all three heads fuse at the carpus to form a single tendon and then subdivide to attach to the palmar aspect of each digit

Superficial Gluteal

Small muscle that overlies the caudal part of the middle gluteal muscle; fibers extend laterally from its origin to the insertion on the femur

Sacrum and coccygeal vertebrae

Superficial Gluteal origin

Femur (greater trochanter)

Superficial Gluteal insertion

Abducts the pelvic limb and extends the hip

Superficial Gluteal action

Middle Gluteal

Large egg-shaped muscle that lies cranial to the superficial gluteal muscle and caudal to the tensor fascia late; fibers are directed caudoventrally to its insertion on the femur

Lateral ilium

Middle Gluteal origin

Femur (greater trochanter)

Middle Gluteal insertion

Abducts the limb and extends the hip

Middle Gluteal action

Biceps Femoris

Longest and widest muscle of the thigh and covers its entire caudolateral aspect; muscle spans over 3 joints and has actions at all 3 (coxofemoral, stifle, tarsus); contributes to common calcanean tendon

Pelvis (ischiatic tuberosity)

Biceps Femoris origin

Patella, proximal tibia, and tuber calcanei

Biceps Femoris insertion

Extends the hip, flexes the stifle, and extends the tarsal joint

Biceps Femoris action

Semitendinosus

Strap-like muscle lies medial to the Biceps femoris and lateral to the semimembranosus; member of hamstring group

Extends the hip, flexes the stifle, and extends the tarsal joint

Semitendinosus action

Semimembranosus

Muscle is not as long semitendinosus, but is slightly thicker; wedged between the biceps femoris (laterally) and gracilis (medially); member of hamstring group

Extends the hip and flexes the stifle

Semimembranosus action

Semitendinosus, semimembranosus, and biceps femoris

The hamstrings consist of…

Pectineus

Small spindle shaped muscle on the medial aspect

Adducts the pelvic limb

Pectineus action

Adductor

Large pyramid shaped muscle in the leg

Adducts the pelvic limb and extends the hip

Adductor action

Sartorius, pectineus, adductor, and body wall

The femoral triangle hallow triangular space that contains the femoral nerve, artery, and vein created by the borders of the…

Rectus femoris, Vastus lateralis, Vastus intermedius, Vastus medialis

The quadriceps femoris s most powerful extensor of the stifle that consists of four heads that fuse distally called the ____________ to form a common tendon

Ilium and proximal femur

Quadriceps Femoris origin

Tibial tuberosity

Quadriceps Femoris insertion

Extends the stifle and flexes the hip

Quadriceps Femoris action

Biceps femoris

Antagonist of the quadriceps femoris

Cranial Tibial

Most cranial muscle of the lower leg; group of cranial muscles are held in place by the extensor retinaculum; strong band of fascia

Flexes the tarsal joint

Cranial Tibial action

Long Digital Extensor

Spindle shaped muscle that lies lateral to the cranial tibial muscle and is partly covered by it; tendons of this muscle run under the proximal extensor retinaculum and divide into the four tendons of insertion

Extends digital joints, flexes tarsal joint and extends the stifle joint

Long Digital Extensor action