Term
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Definition
Cells closely packed together that are capable of contracting when stimulated by an electrical (nerve) impulse |
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Term
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Definition
a. Appearance: spindle-shaped; centrally-located nucleus; no striations (vertical cross-bands); not branched b. Location: skin blood vessels; urogenital organs, respiratory organs, alimentary organs, ducts c. Function: involuntary action; stimulated by the autonomic nervous system |
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Term
| Cardiac Muscle Appearance |
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Definition
cylindrical; centrally-located nuclei separated by prominent cross-bands called intercalated disks; striations present due to the arrangement of thick and thin protein filaments (the following information [i-iv] also applies to skeletal muscle)
i. Thick filaments: primarily myosin
ii. Thin filaments: actin, tropomyosin, and troponin
iii. A contractile unit (“sarcomere”) is formed of the following combination of filaments: thick—thin—thick
iv. Contraction occurs when the myosin head bond to the thin filaments and then swivel so as to draw the thick and thin filaments past one another |
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Term
| Cardiac Muscle Location and |
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Definition
a. Location: heart Function: essentially involuntary ; rhythm controlled by autonomic fibers |
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Term
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Definition
a. Appearance: cylindrical; multinucleate; striated; not branched b. Location: usually attached to skeletal elements (bones or cartilage) c. Function: controls locomotion, including limb movement; a single neuron controls the contraction of 100-2000 muscle fibers (a “motor unit”), which contract at the same time |
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Term
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Definition
(a) A muscle is a bundle of fibers
(b) Bundles of fibers are made up of individual fibers
(c) Individual fibers are made up of fibrils
(d) Fibrils are made up of sarcomeres (thick and thin protein filaments) |
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Term
| What holds muscle components together? |
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Definition
membranes (connective tissue)
(a) Epimycium: around the entire muscle
(b) Perimycium: around each bundle of fibers
(c) Endomycium: around single fibers |
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Term
| How do skeletal muscles attach to the skeletal system or to other muscles? |
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Definition
(a) Thick, cordlike attachment: Tendons (fig. 10.2)
(b) Thick, sheetlike attachment: Aponeuroses
(c) Thin, sheetlike attachment: Fasciae |
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Term
Extensors Flexors Adductors Abductors Levators Depressors |
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Definition
Extensors: increase the angle between adjacent bones
Flexors: decrease the angle between adjacent bones
Adductors: move parts inward (e.g., toward the sagital plane)
Abductors: move parts outward (e.g., away from the sagital plane)
Levators: raise structures (e.g., jaw, shoulders)
Depressors: lower structures |
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Term
Rotators
Protractors
Retractors
Constrictors or Sphincters
Dilators |
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Definition
Rotators: twist segments about their axis
- Supinators: turn upward (e.g., palms or soles)
- Pronators: turn downward
Protractors: Push away from the base (e.g., the tongue)
Retractors: Draw back to the base
Constrictors or Sphincters: compress spaces (e.g., the gut tube)
Dilators: open spaces |
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Term
| Antagonists and Synergists |
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Definition
Antagonists are muscles whose actions act in opposition (e.g., extensors or flexors)
Note: Joints can be stiffened by simultaneously contracting antagonistic muscles.
Synergists are muscles that have the same general function (e.g., biceps brachii and brachialis both flex the upper arm) |
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Term
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Definition
- The most stable end of attachment is called the origin
- In limbs, the more proximal end is considered as the origin
- Around joints, muscles often work as lever systems (fig.’s 10.14 and 10.15)
• Proximal insertions allow most rapid movement while distal insertions provide stronger movement
• For a given distance of muscle shortening, proximal insertions provide a greater sweep distance |
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Term
| Orientation of Muscle Fibers |
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Definition
(a) Parallel to longitudinal axis
• fibers are typically long and so allows relatively long length of contraction
• few fibers can be packed into the space, so contractions are relatively weak (b) Pinnate: fibers are at an oblique angle to the long axis
• fibers are typically short and so there is a relatively short length of contraction
• many fibers can be packed into the space, and so contractions have stronger force |
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Term
| Determining Muscle Homologies |
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Definition
- Difficult due to numerous splits, fusions, and shifting insertion points
- Methods:
(a) Paleontology: muscle scars on bones
(b) Embryology: useful for muscle groups but not for individual muscles
(c) Nerve supply: most used for individual muscles |
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Term
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Definition
- Run between the ventral elements of the gill arches and between the gill arches and the pectoral girdle; these muscles contribute to the tongue
- Arise from the trunk somites
- Are innervated by spinal nerves |
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Term
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Definition
- Muscles of the gill arches
- Arise from the somitomeres (unsegmented “somites” in the head region)
- Innervated by cranial nerves |
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Term
Sharks
Branchiomeric Muscles
(Major derivatives of first and second gill arches) |
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Definition
- Levator palatoquadrati: elevates the upper jaw (10.29)
- Adductor mandibulae: connects upper and lower jaws; for biting or grinding (10.29)
- Preorbitalis: runs in front of the orbit; pulls the jaw to the braincase (no figure)
- Intermandibularis: runs transversely between ventral edges of mandibles (10.30)
- Interhyoideus: runs transversely between hyoid bars (no figure, deep muscle) |
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Term
Bony fishes
Branchiomeric Muscles
(Major derivatives of first and second gill arches) |
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Definition
| similar to sharks with additional muscles associated with the operculum |
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Term
Tetrapods:
Branchiomeric Muscles
(Major derivatives of first and second gill arches) |
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Definition
- Levator palatoquadrati: - Adductor mandibulae: - Interhyoideus - Jaw Depressors |
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Term
| Tetrapods Levator palatoquadrati: |
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Definition
- Squamate reptiles; birds: elevates upper jaw
- most amphibians, other reptiles, and mammals: usually absent; the upper jaw is fused to the braincase, so there would be no function for this muscle |
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Term
| Tetrapods Adductor mandibulae: |
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Definition
- Amphibians/Reptiles: may be heavily subdivided
- Mammals: 3 parts
1) Temporalis: retains much of the original position (10.38)
2) Masseter: more superficial (completely external to the skull); arises at the zygomatic arch and inserts on the lower portion of the mandible (10.38)
3) Pterygoideus: a deep muscle that arises at the pterygoid and inserts on the inner or back surface of the jaw (no figure, deep muscle) |
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Term
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Definition
| forms additional muscles, the constrictor colli, which form face muscles (most prominently, the platysma) |
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Term
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Definition
- Depressor Mandibulae: derived from a hyoid and an opercular muscle; attaches at back of lower jaw; opens mouth (10.39c)
- amphibians/reptiles: same as fishes
- mammals: reduced in size to the stapedius (no figure) -Digastric (mammals only): anterior belly is derived from the intermandibularis; posterior belly derived from the hyoid constrictors (Fig. 10.30c) |
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Term
| Major derivatives of posterior arches (supports shoulder) |
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Definition
- Fishes, amphibians: Cucullaris (10.29)
- Reptiles, mammals: Trapezius (homologous with cucullaris) (Fig. 10..33) |
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Term
Major Hypobranchial Muscles
Fish Amphibian Mammal |
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Definition
Fish:
-Coracoarcuales
-Coracomandibularis
-coracohyoid Amphibian:
-Tongue muscles
-Geniohyoid
-Rectus cervicis Mammal:
-Tongue muscles
-Geniohyoid
-Sternohyoid & Sternothyroid |
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Term
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Definition
Development: arise from 3 (or maybe 4) head somitomeres Tetrapods may have additional muscles due to the splitting of pre-existing muscles.
- Retractor bulbi: developed from the lateral rectus; functions to pull the eye back into the socket; prominent in amphibians and most reptiles, but often lacking in birds and mammals |
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Term
| -Anterior-most somitomere gives rise to: |
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Definition
- Dorsal (= Superior) Rectus (fig. 10.23)
- Ventral (= Inferior) Rectus (no fig.)
- Medial Rectus (fig. 10.23)
- Ventral (= Inferior) Oblique (no fig.)
These muscles are innervated by Cranial Nerve III (oculomotor) |
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Term
| Middle somitomere gives rise to: |
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Definition
Dorsal (= Superior) Oblique (fig. 10.23)
It is innervated by Cranial Nerve IV (Trochlear) |
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Term
| Posterior-most somitomere gives rise to: |
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Definition
Lateral Rectus (fig. 10.23)
It is innervated by Cranial Nerve VI (Abducens) |
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Term
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Definition
- Found only in mammals
- Separates abdominal and thoracic cavities (anterior to the liver)
- Apparently derived from the anterior portion of the Rectus abdominis muscle
- A few nonmammals (e.g., crocodilians) have similar abdominal/thoracic separations, but these are apparently not homologous to the diaphragm (these are posterior to the liver). |
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Term
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Definition
- a derivative of muscle (stacked layers of cells called electroplaxes)
- Instead of contracting in response to nerve impulses, these cells produce an electric charge
- In some fishes the jolt of voltage is sufficient to stun prey (or predators); e.g., skates, electric eels, electric catfishes
- Other fishes produce a weak electric field around their bodies that allow them to detect any object disrupting the field (Fig 17.47)
- The diversity of occurrence, location, and structure suggests that electric organs have evolved independently a number of times and are an example of convergent evolution (fig. 10.1)
- function: Food capture, defense, communication and navigation |
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Term
Axial Skeletal Muscle origin
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Definition
| derived from primarily from myotomes (part of the epimere) |
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Term
Appendicular Skeletal Muscle origin
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Definition
derived from: -> Myotomes: more important in fishes -> The somatic (outer) portion of the hypomere: both fishes and tetrapods -> Mesenchyme (amoeboid mesoderm): more important in tetrapods |
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Term
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Definition
| derived from the splanchnic (inner) portion of the hypomere |
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Term
| Smooth Muscle (alimentary canal and derivatives) Origin |
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Definition
derived from the splanchnic hypomere |
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Term
Axial Skeletal Muscles in Fishes |
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Definition
Structure: segmented myomeres (derived from myotomes) that are separated from each other by sheets of connective tissue called myosepta
-> Agnathans: Lateral muscle is a single unit
-> Gnathastomes: Lateral muscle is divided into two layers by a horizontal septum (fibrous connective tissue):
- Epaxial muscle=dorsally / Hypaxial muscle=ventrally
Innervation: Spinal nerves bifurcate after leaving the spinal cord:
-> The Dorsal Ramus supplies the epaxial muscle
-> The Ventral Ramus supplies the hypaxial muscle
Movement: Muscular contractions alternate from side to side, producing waves of lateral undulations |
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Term
| Axial Skeletal Muscles inTetrapods |
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Definition
Trend: specialization for more complex control of the vertebral column and rib cage. |
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Term
| Axial Skeletal Muscles in Amphibians |
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Definition
-> Horizontal septum and segmentation (including myosepta) is retained -> Expaxial muscles: dorsalis trunci -> Hypaxial muscles are differentiated into three layers: - Inner-most layer: transversus - Intermediate layer: internal oblique - Outer layer: external oblique and rectus (divided into left and right halves by connective tissue, the linea alba) |
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Term
| Axial Skeletal Muscles in Reptiles |
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Definition
-> No horizontal septum. Muscles are identified as derivatives of epaxial and hypaxial on the basis of innervation (dorsal versus ventral ramus of spinal nerves)
-> Epaxial muscle has split: transversospinalis, longissimus, and iliocostalis
-> Hypaxial muscles: same 4 muscles as in amphibians, plus the subvertebralis and intercostalis
-> Some specializations:
- turtles: hypaxial muscles are lost or greatly reduced
- snakes: well developed axial muscles with further splits |
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Term
Axial Skeletal Muscles in Mammals |
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Definition
-> Same basic divisions as reptiles -> Numerous splits have yielded additional muscles |
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Term
Support for Tetrapod Pectoral and Pelvic Girdles |
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Definition
- The pectoral girdle is supported by a “sling” of axial muscles (Fig. 10.28) - Pelvic girdle supported not by muscles, but by fusion of the girdle to the vertebral column |
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Term
Fishes Appendicular Skeletal Muscles |
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Definition
Two opposing muscle groups: - Dorsal group: Act as extensors, abductors, or levators - Ventral group: Act as flexors, adductors, or depressors |
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Term
Tetrapods Pectoral Girdle and Limb: |
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Definition
derived from three sources: Branchiomeric
Axial
Appendicular |
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Term
| Tetrapods Pectoral Girdle and Limb: Branchiomeric muscles: |
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Definition
- Innervated by cranial or cervical nerves
- Form the trapezius and mastoid muscle groups |
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Term
| Tetrapods Pectoral Girdle and Limb: Axial muscle: |
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Definition
- Innervated by the ventral rami of spinal nerves that are not a part of the brachial plexus (a network of nerves at the base of the limbs)
- include levator scapulae, the rhomboideus complex (dorsal “neck” muscle), and serratus muscles |
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Term
| Tetrapods Pectoral Girdle and Limb: Appendicular muscles: |
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Definition
- Innervation by the ventral rami of spinal nerves that enter the brachial plexus
- Major derivatives of dorsal appendicular muscles (mostly extensors):
-> latissimus dorsi, teres major/minor (no fig. deep), deltoideus, triceps
- Major derivatives of ventral appendicular muscles (mostly flexors):
-> pectoralis, coroco(=clavo)brachials, and biceps brachii |
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Term
| Tetrapods Pelvic Girdle and Limb |
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Definition
- One muscle was derived from axial muscle: Psoas minor - Others were derived from appendicular muscle: |
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Term
Tetrapods Pelvic Girdle and Limb Major Dorsal derivatives |
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Definition
(mostly extensors): -> Puboischiofemoralis internus; mammals = psoas, iliacus,& pectineus—no figure -> Iliofemoralis; mammals = tensor fasciae latae, the Pyriformis, and the gluteus complex -> Quadriceps: the rectus femoris and the three heads of the vastus) -> Amphibians = iliotibialis, Reptiles = ambiens , Mammals = sartorius |
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Term
Tetrapods Pelvic Girdle and Limb Major Ventral derivatives |
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Definition
(mostly flexors): -> Puboischiofemoralis externus; in mammals = obturator externus and the quadratus femoris -> Caudofemoralis (reduced in mammals): flexes tail -> The “hamstrings”: flexes lower leg - Amphibians = Ischioflexorius - Reptiles = Flexor tibialis internus/externus - Mammals = Semimembranosus , semitendonosus, biceps femoris -> Puboischiotibialis; mammals = gracilis -> Gastrocnemius: flexes foot |
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