Axial Musculature vs. Appendicular Musculature

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  1. Axial muscles

    - include
    - extend
    - present in
    - special characteristic
    - include the skeletal muscles of the trunk and tail

    - extend forward beneath the pharynx as hypobranchial muscles and muscles of the tongue

    - they are also present in orbits as extrinsic eyeball muscles

    - they are metameric in fish and aquatic amphibians and are used in locomotion

    - in tetrapods, metameric properties cannot be seen due to the presence of paired appendages
  2. Axial: Trunk and tail muscles of fish
    axial musculature consists of a series of segments known as myomeres or myotomes
  3. Myomeres
    are separated by a sheet of connective tissue called myosepta; collagen is arranged in a grid-like formation which gives it the ability to bend laterally but not longitudinally. This gives fish the ability to move its body from side to side
  4. Myomeres are divided
    into dorsal and ventral masses by horizon septum

    epaxials= above the septum

    hypaxials= below the septum
  5. Axial: trunk and tail muscles of tetrapods
    like fish, they have epaxial and hypaxial masses but have a series of modifications to their axial muscle system

    modifications: epaxials and hypaxials
  6. Epaxials
    are elongated bundles that extend through many body segments and are located below the expanded appendicular muscles
  7. hypaxials
    hypaxials of the abdomen have no myosepta and form broad sheets of muscle and they are oriented into oblique, rectus, and transverse bundles
  8. Epaxials of tetrapods
    Lie along the vertebral column, is dorsal to transverse process, adn is lateral to neural arches

    extend from base of skull to the tip of the tail 

    form the dorsalis trunci muscles

    function in aiding with side to side movements of vertebral columns

    short and long bundles arch and support the vertebral column

    anterior bundles attach and move the skull
  9. Hypaxials of tetrapods
    Form the muscles of the lateral body wall: external and internal oblique, transverse, and rectus muscles

    Assist in locomotion, support contents of the abdomen, assist in respiration, and assist epaxials in bending the vertebral column
  10. Appendicular muscles
    muscles located on girdles, limbs, and fins

    extrinsic: originate on axial skeleton and insert on girdles or limbs

    intrinsic: originate on girdle and insert on the distal elements

    appendicular muscles are more complex in tetrapods due to the accommodation for terrestrial life
  11. Appendicular: muscles of fish
    • muscles serve as stabilizers
    • dorsal and ventral components of embryonic mscles bud from extensors and flexors
    • paired fins operation as unjointed appendages
    • the intrinsic muscles are limited in number and are undifferentiated
  12. Appendicular: muscles of tetrapods
    very complex muscle system to accomplish locomotion on land and jointed appendages (as opposed to fins)

    muscles are organized as opposing groups and classified as intrinsic or extrinsic

    extrinsic muscles (primitive) originate from blastemas within the body wall and insert on girdle or proximal to limb bones

    intrinsic appendicular muscles originate from blastemas, located within the developing limb
  13. Appendicular: extrinsic muscles of tetrapods
    extrinsic muscles of the pectoral girdle and forelimbs are divided into the dorsal group and the ventral group
  14. Appendicular: extrinsic muscles of tetrapods
    -dorsal group
    dorsal group of forelimbs include muscles such as trapezius and latissimus dorsi arise on: 

    • 1) fascia of trink in lower tetrapods
    • 2) skull, vertebral column and ribs, behind the scapula
  15. Appendicular: extrinsic muscles of tetrapods
    -ventral group
    ventral group includes muscles such as pectoralis major and minor and the supracoracoideus (Birds), which developed into the intrinsic muscle called the supracoracoid
  16. Appendicular: extrinsic muscles of tetrapods
    - referred to as
    - chief extrinsic muscles incldue
    - most develop from hypaxial blastemas in the body wall

    - it is referred to as secondary appendicular muscles because it was not their original function to operate appendages

    - chief extrinsic muscles of tetrapods include: scupular deltoid, latissimus dorsi, rhomboideus, serratus ventralis and pectoralis
  17. Appendicular: intrinsic muscles of tetrapods
    - form from
    - called
    - development
    • form from blstemas within the limb bud
    • called primary appendicular muscles

    intrinsic muscles of the pectoral girdle and forelimbs are divided into the dorsal group and the ventral group
  18. Appendicular: intrinsic muscles of tetrapods
    - dorsal group
    dorsal group includes muscles that arise on the scapula and insert on the humerus such as deltoideus, teres major and minor, and long head of triceps brachii
  19. Appendicular: intrinsic muscles of tetrapods
    - ventral group
    ventral group include muscles of the pectoral girdle that includes supraspinatus, infraspinatus, bicep brachii, and brachialis
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Axial Musculature vs. Appendicular Musculature
2015-10-25 02:17:46
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