Module 3

• Muscle Criteria (4)

  1. Attachment similarity
  2. function similarity
  3. innervation similarity
  4. embryonic origin
• Skeletal Muscle Properties (3)

  1. striated
  2. voluntary
  3. associated with bones and cartilage
• Cardiac muscle Properties (3)

  1. in branchial heart only
  2. banding pattern
  3. involuntary
• Smooth muscle Properties (3)

  1. no striations
  2. visceral functions
  3. digestive tract movements
  4. blood vessels
  5. lungs
  6. slow and sustained contraction
• Muscle fiber 


  whole muscle cell
• Endomysium 


  wraps muscle cell
• Perimysium


  wraps grasps of muscle cells
• Epimysium


  wraps entire muscle organ
• Tendon


  cordlike attachments from muscle to the bone
• Aponeurosis


  flat, tough connective tissue
• Fascia


  wraps and binds the body
• Myoglobin-rich fibers


  responsible for the red color of muscle fibers; fatigue-resistant
• Less vascularized


  why muscle fibers are white; rapid contractions
• Tonic fibers

  1. slow-contracting
  2. low force
  3. sustained contraction
• twitch fibers

  1. fast-contracting
  2. mostly somatic
• Slow twitch fibers 


  longer time to max force
• Fast twitch fibers 


  faster generation of max force
• Muscle homology

  
• axial musculature: horizontal septum divides dorsal/ventral myotomes
• in Fishes...


  the segmented axial structures develop into myomeres
• Myosepta 


  separating myomeres in fish muscles
• V/W shape allows lateral undulation
• Horizontal septum is absent in lampreys
• Muscle arrangement of fishes allows undulation
• Horizontal septum in reptiles is lost or indistinct
• vertebral column in reptiles contributes to locomotion (lateral undulations)
• Reptile limbs are more important for propelling
• Epaxial muscles are split into three layers

  1. transversospinalis
  2. longissimus
  3. iliocostalis
• Hypaxial muscle groups in Reptiles (tetrapods) include:

  1. dorsomedial
  2. medial
  3. lateral
  4. ventral
• Aves have reduced axial musculature, more so in regions of fused vertebrae.
• The epaxial and hypaxial muscles of mammalians split
• Intercostal and oblique muscles 


  run between the pelvis and the ribcage and between adjacent sets of ribs.
• Mammals - absence of ribs in abdomen (intercostals and obliques)
• dorsal and ventral appendicular muscle masses of fishes run from the girdle to the pterygiophore
• Fish appendicular ventral muscles - depress/adduct fin
• Tetrapods have more complex limb structures
• Muscular sling 


  hangs the pectoral girdle in tetrapods
• Muscular sling hangs pectoral girdle

  • axial, branchial, forelimb musculature
• Branchiomeric

  trapezius and mastoid groups along the pectoral girdle and forelimbs of tetrapods
• Axial muscles in the pectoral girdle and forelimbs of tetrapods

  1. levator scapulae
  2. rhomboideus complex
  3. serratus