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Muscle tissue 1 2 (comparative vertebrate anatomy)
The document discusses the muscular system, describing four main types of vertebrate muscles and their functions. It focuses on axial muscles, including those in the trunk, tail, hypobranchial region, and tongue. In fish, axial muscles are segmented into myomeres, while tetrapods retain some evidence of segmentation. Epaxial muscles extend along the spine dorsally while hypaxial muscles include lateral body wall muscles and subvertebral muscles. Hypobranchial muscles originate in the pharyngeal region and migrate forward in tetrapods.
Muscle tissue 1 2 (comparative vertebrate anatomy)
- 1. Muscular System • Function –Locomotion – Posture – Protection – Heat production
- 2. • Vertebrate muscles: •striated vs. smooth • voluntary vs. involuntary • skeletal vs. non-skeletal • Skeletal muscle (left) & Smooth muscle (right)
- 3. Muscle Classification • SkeletalMuscle – Attached to skeleton – Striated – Muscle fiber = Muscle cell • Multinucleate • Myofibrils are striated cylinders within myofiber • Non-skeletal muscle = muscles not attached to the skeleton; most are smooth & involuntary
- 4. • 1 -Skeletal, striated, voluntary muscles – axial • body wall & tail • hypobranchial & tongue • extrinsic eyeball muscles – appendicular – branchiomeric (homologous to the branchial/ pharyngeal muscles from fishes to mammals, striated muscles, innervated by cranial nerves) – integumentary
- 5. • 2 -Non-skeletal, smooth, chiefly involuntary muscles –muscles of tubes, vessels, & hollow organs –intrinsic eyeball muscles –erectors of feathers & hair • 3 - Cardiac muscle • 4 - Electric organs
- 6. • Skeletal muscleshave muscular & tendinous portions: • Muscle - consists of skeletal muscle cells (which, in turn, consist of myofibrils and myofilaments) • Tendons - extensions of a muscle's tough connective tissue sheath (fascia & epimysium) that anchor a muscle to its origin & insertion
- 8. –Origin = siteof attachment that is relatively fixed –Insertion = site of attachment that is normally displaced by contraction of the muscle
- 9. •Names of skeletalmuscles are based on: •direction of fibers (e.g., oblique( •location or position (e.g., superficial( •number of divisions (e.g., triceps( •shape (e.g., deltoid( •origin and/or insertion (e.g., iliocostalis( •action (e.g., levator scapulae( •size (e.g., major( •or some combination of these
- 13. Skeletal Muscle • Myofilamentsare proteins that result in contraction within the myofibrils –Actin – thin & has a receptor site for myosin –Myosin – thick & has a receptor site for actin and ATP –Contraction – Myosin heads attach to actin and with ATP perform a Power Stroke
- 17. Skeletal Muscle •Sarcomere •The distancefrom Z line to Z line •The basic unit of contraction •Sarcomere gets smaller as Power Stroke occurs
- 18. Key Points • Whyis the sarcomere the functional unit of contraction? • Why does the power stroke result in contraction? • What would happen to contraction if you ran out of ATP?
- 19. Motor Neurons • Skeletalmuscle cannot contract without stimulation from a motor neuron • Motor Unit = The motor neuron plus the myofiber(s) it innervates
- 21. Key Points • Whywould a spinal cord injury result in paralysis?
- 22. Somatic Muscles • Allof the body’s skeletal muscles except the branchiomeric muscles • Voluntary • Body wall & Appendage muscles – Trunk and Tail – Hypobranchial – Tongue – Extrinsic Eyeball
- 23. Somatic Muscles • Myotomederivatives primarily • Some from hypomere
- 24. Key Points • Whatis a myotome?
- 26. Somatic Muscles • Orientthe body in the environment
- 27. Somatic Muscles • RedFibers – More blood supply for aerobic metabolism – Myoglobin for oxygen storage – Fatigue resistant – Fish for cruising long distances, tetrapods for posture
- 28. Somatic Muscles • Whitefibers – Less blood supply; geared for anaerobic metabolism – Fatiguable – Fish for spurts of swimming – Tetrapods for sprints
- 29. Key Points • Whyis the breast meat of the goose dark, but the breast meat of the chicken is white?
- 30. Cardiac Muscle • Striatedwith intercalated disks • Involuntary • Lateral plate mesoderm (hypomere) in origin
- 32. Smooth Muscle • Involuntary •Lateral plate mesoderm in origin • Regulates internal environment • Innervated by Autonomic Nervous System • Found in the wall of tubes and hollow organs • Intrinsic Eye muscles • Erectors of feathers and hairs
- 34. Key Points • Besidesthose mentioned, give a specific example of where might you find smooth muscle?
- 35. Gross features ofskeletal muscle • Origin, insertion • Tendon • Aponeurosis • Fascia
- 38.
- 39. Skeletal Muscle Actions •Flex/Extend • Adduct/Abduct • Levator/Depressor • Protract/Retract • Constrictor/Dilator • Rotator
- 41. Skeletal Muscle Actions •Supinator/Pronator • Tensor (taut)
- 42. Skeletal Muscle Actions •Agonist – primary mover • Antagonist – opposes primary mover • Synergist – helps primary mover
- 43. Development & Phylogeny •Position • Embryology • Nerve supply
- 44. Development • Dorsal Mesoderm– Epimere – Somite –Myotome –Sclerotome & Dermatome • Lateral plate Mesoderm – Hypomere –Somatic – body wall muscles –Splanchnic – smooth muscle of viscera
- 46. AXIAL MUSCLES • Trunk •Tail • Hypobranchial • Tongue • Extrinsic Eye
- 47. • Axial Muscles: •include the skeletal muscles of the trunk & tail • extend forward beneath the pharynx as hypobranchial muscles & muscles of the tongue • are present in orbits as extrinsic eyeball muscles (check slide 27 in this powerpoint presentation) • are metameric (most evident in fish and aquatic amphibians where the axial muscles are used in locomotion; in other tetrapods, metamerism is obscured due to presence of paired appendages responsible for locomotion on land) • are segmental because of their embryonic origin; arise from segmental mesodermal somites
- 49. •Trunk & tailmuscles of fish: •Axial musculature consists of a series of segments (myomeres) separated by myosepta –Myosepta serve as origins & insertions for segmented muscles •Myomeres are divided into dorsal & ventral masses by a horizontal septum that extends between the transverse processes of the vertebrae
- 50. •Epaxials = abovethe septum •Hypaxials = below the septum
- 51. • Trunk &tail muscles of tetrapods • Tetrapods, like fish, have epaxial & hypaxial masses, & these retain some evidence of metamerism even in the highest tetrapods. • Modifications: • 1 - epaxials are elongated bundles that extend through many body segments & that are located below the expanded appendicular muscles required to operate the limbs • 2 - hypaxials of the abdomen have no myosepta & form broad sheets of muscle • 3 - hypaxials are oriented into oblique, rectus, & transverse bundles
- 52. • Epaxials oftetrapods: • lie along vertebral column dorsal to transverse processes & lateral to neural arches • extend from base of the skull to tip of the tail
- 53. •Hypaxials of tetrapods: •1-Musclesof lateral body wall: –oblique (external & internal), transverse, & rectus muscles •2-Muscles that form longitudinal bands in roof of body cavity (subvertebral muscles(
- 55. Rectus muscles: •weakly developedin most fish; 'stronger' in tetrapods •support ventral body wall & aid in arching the back •in mammals - rectus abdominis (typically extends from the anterior end of the sternum to the pelvic girdle)
- 57. Appendicular muscles -move fins or limbs •Extrinsic - originate on axial skeleton or fascia or trunk & insert on girdles or limbs •Intrinsic - originate on girdle or proximal skeletal elements of appendage & insert on more distal elements
- 58. Branchiomeric muscles: 1 -associated with the pharyngeal arches 2 - series of skeletal & smooth muscles 3 - adductors, constrictors, & levators operate jaws plus successive gill arches
- 59. Integumentary muscles: Extrinsic integumentarymuscles (e.g., platysma) •originate (usually) on the skeleton & insert on the underside of the dermis •striated •move skin of amniotes Intrinsic integumentary muscles (arrector pili muscles) •entirely within the dermis •found in birds & mammals mostly smooth muscles
- 60. Axial Muscles •Metamerism asin myomeres
- 62.
- 63. Axial Muscles –Jawed Fish • Horizontal or Lateral Septum • Epaxial Muscles – From myotomes in embryology – Innervated from dorsal rami of spinal nerves – Extend spine & some lateral bending – Extrinsic eye muscles (innervated by cranial nerves) – Epibranchial muscles
- 66. Axial Muscles –Jawed Fish •Hypaxial Muscles •From Myotomes –Innervated by ventral rami of spinal nerves –Ventroflex and lateral bending
- 68. Hypaxial Muscles –Jawed fish •Hypobranchial muscles •Located on floor of pharynx, pectoral girdle to jaw •Are hypaxial muscles that migrated forward •Function in respiration & feeding •E.g. Coracomandibularis, Coracohyoid
- 70. Axial Muscles -Tetrapods •Epaxial trunk muscles •Dorsal muscles from skull to tail •Dorsalis trunci in amphibians •Longissimus – long dominant spine extensor in amniotes •Iliocostalis – most lateral epaxial spine muscle important in reptiles
- 73. Epaxial Muscles •See VertebrateMuscles page
- 74. Epaxial Muscles inTetrapods • Trends • Decreased except in neck • Fewer myosepta
- 75. Axial Muscles -Tetrapods • Hypaxial Muscles • Tend to form sling-like sheets • Lateral muscles support & compress body wall • Obliques • Transversus • Intercostals in amniotes only
- 77. Hypaxial Muscles -Tetrapods • Rectus abdominis – ventroflexes and compresses abdomen • Diaphragm – unique to mammals for breathing
- 79. Hypaxial Muscles intetrapods •See Vertebrate Muscles page
- 80. Hypobranchial and TongueMuscles - tetrapods • Function – stabilizes hyoid and larynx • E.g. geniohyoid, sternohyoid, sternothyroid, thyrohyoid
- 82. Hypobranchial & Tonguemuscles in tetrapods •Tongue muscles •Lingu-; Gloss- •Anchors to hyoid •E.g. lingualis, styloglossus
- 83. Hypobranchial & Tonguemuscles in Tetrapods • See Vertebrate Muscles page
- 84. Extrinsic Eye musclesin tetrapods • Voluntary • Obliques – rotates eye along its transverse axis • Rectus – up, down, left, right • Retractor in some
- 86. Extrinsic Eye muscles •See Vertebrate Muscles Page