Lecture 2: Muscular System

• What is the muscular system composed of?

  Contractile units called muscle fibers
• What are the primary functions of the muscular system?

  Locomotion, respiration, circulation, alimentation
• How do muscles indicate emotional states?

  Through barking, facial expressions, and tail wagging
• Where are cutaneous muscles located?

  Beneath the skin
• What is the primary responsibility of cutaneous muscles?

  Responsible for skin movement
• What are the key muscles and their characteristics in domesticated animals?

  • Frontalis: Over frontal bone, in man, ruminants, pigs
  • Cutaneous colli: Neck region, best in horses
  • Cutaneous trunci: Covers trunk, in all except man
  • Cutaneous omo brachialis: Over shoulder and arm, in horses and ruminants
• What are the components of the brachiocephalicus muscle in dogs?

  Cleidobrachialis, cleidocervicalis, cleidomastoideus
• What are the components of the sternocephalicus muscle in dogs?

  Sternooccipitalis, sternomastoideus
• How is the pectoralis muscle characterized in dogs?

  Narrow and band-shaped, difficult to distinguish
• What is unique about the deep pectoral muscle in dogs?

  Divided into major and minor portions
• What is the status of the subclavius muscle in ruminants?

  Narrow and poorly developed
• How does the deltoideus muscle differ in horses compared to dogs?

  Fused parts, no distinct acromion
• How many heads does the triceps brachii have in dogs?

  Four heads
• How many heads does the triceps brachii have in ruminants?

  Three heads
• What is the insertion pattern of the common digital extensor in dogs?

  Single tendon into all five digits
• How does the common digital extensor differ in ruminants?

  Two tendons into functional digits 3 and 4
• Where does the lateral digital extensor insert in dogs?

  Digits 3, 4, and 5
• What is the function of the pronator teres muscle?

  Pronates the paw
• What is the status of the internal obturator muscle in cattle and pigs?

  Absent, replaced by external obturator
• How does the biceps femoris muscle differ in cattle compared to dogs?

  Fused with superficial gluteal muscle
• What is the status of the soleus muscle in different animals?

  • Dog: Absent
  • Ruminant: Present but narrow
  • Horse: Present but narrow
  • Pig: Present and well-developed
  • Cat: Present
• What are the roles of the pectoral and supracoracoid muscles in birds?

  • Pectoral Muscle: Downbeat of wings, generates lift
  • Supracoracoid Muscle: Upbeat of wings, less developed
• What is the collective name for the two heads of the gastrocnemius and soleus muscle?

  Triceps surae
• How does the development of the pectoral muscle compare to the supracoracoid muscle in birds?

  Pectoral muscle is highly developed
• What is the difference in the development of the supracoracoid muscle compared to the pectoral muscle in birds?

  Supracoracoid is less developed than pectoral
• What is the primary function of the pectoral muscle in birds?

  Responsible for the downbeat of the wings
• What is the primary function of the supracoracoid muscle in birds?

  Responsible for the upbeat of the wings
• How does the pectoral muscle contribute to flight in birds?

  Generates lift during the downbeat of wings
• How do the characteristics of the pectoral and supracoracoid muscles affect a bird's flight?

  Pectoral is crucial for lift; supracoracoid aids recovery