VANA 102: MYOLOGY

• types of muscle tissue

  smooth, skeletal, cardiac
• functions of the muscular system:

  • varied functions are all based on contraction (shortening) of muscle fibers
  • heat production
  • maintain posture
  • locomotion- permits movement
• skeletal muscles organization:

  • muscle fiber bundles
  • muscle fiber arrangement
  • muscle attachment
  • fleshy attachment
• muscle fiber bundles:

  • endomysium
  • perimysium
  • epimysium
• muscle fiber arrangement:

  • strap/parallel
  • pennate/penniform
  • fusiform
• muscle attachment:

  • tendinous
  • aponeurotic
• fleshy attachment:

  • origin and insertion
  • head and belly
• muscle of the side of the limb toward which the joint bends

  flexor
• muscle on the opposite side of the flexor muscles

  extensor
• an example of a flexor on the cranial side of the limb and flexes the elbow

  biceps brachii
• an example of a extensor that is on the caudal side of the limb the is the extensor of the elbow

  triceps brachii
• a flexor of the stifle

  gastrocnemius
• extensor of the hock

  gastrocnemius
• muscles that tend to pull the limb towards the median plan

  adductor
• muscle that tends to move a limb away the median plane

  abductor
• muscles that surround an opening, whether striated or not

  sphincters
• a muscle found in the superficial fascia between the skin and deep fascia covering the skeletal muscle

  cutaneous muscle
• a muscle that is attached to the skin, responsible for the movement of the skin


  cutaneous muscle
• synovial structures:

  • joint capsule
  • bursa
  • synovial sheath
• a synovial sac between 2 structures that tend to rub against each other (bwn tendon, ligament, bony prominence)

  bursa
• resembles an elongated bursa with edge of the bursa reflected around the tendon until they meet

  synovial sheath
• surrounds tendon over a great distance and facilitates for frictionless motion

  synovial sheath
• double fold of membrane where the edge of the synovial sheath meet

  mesotendon
• three parts of synovial sheath:

  • exotendon
  • mesotendon
  • endotendon
• important synovial bursa of the THORACIC limb of horse:

  • infraspinatus bursa
  • intertubercular bursa
  • subcutaneous olecranon bursa
  • subcutaneous (precarpal) bursa
  • subtendinous bursa of common and lateral digital extensor
  • navicular bursa
• between the tendon of the infraspinatus and the caudal part of the greater tubercle of the humerus

  infraspinatus bursa
• underlies the biceps tendon between the greater and lesser tubercle of humerus

  intertubercle bursa
• over the olecranon bursa - inconstant

  subcutaneous olecranon bursa
• on the dorsal surface of the carpus

  subcutaneous (precarpal) bursa
• lies between the canon bone and tendons of these muscle

  subtendinous bursa of common and lateral digital extensors
• between deep flexor tendon and navicular bone

  navicular bursa
• where can you find synovial sheaths?

  distal part of limb
• synovial sheaths begin approx. on a level with upper edge of accessory carpal and they vary in length
• synovial sheath on the forelimb of horses and their length:

  • extensor carpi radialis - short
  • extensor digitorum communis - long
  • extensor digiti quinti (v) - long
  • abductor polliicis (i) longus - oblique
  • flexor carpi radialis - short
  • ECU (lateralis ularis) and FCU has NO SHEATH
• common sheath enclosing the tendon of superficial and deep flexors.

  carpal sheath
• Begins 10 cm above the radiocarpal joint and ends at the middle of metacarpus

  carpal sheath
• enclose the deep and superficial flexor tendons

  digital sheath
• begins distal 4th of metacarpus and ends at mid 2nd phalanx

  digital sheath
• In both sheath (carpal and digital) the deep flexor is surrounded wholly and superficial flexor is surrounded partly
• important synovial bursa in the HINDLIMB of the horses:

  • trochanteric bursa
  • proximal infrapatellar bursa
  • distal infrapatellar bursa
  • subtendinous calcanean bursa
  • subcutaneous calcanean bursa
  • subtendinous (cunean) bursa of the medial tibialis cranialis tendon
  • navicular bursa