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The Muscles ( Myology )

The Muscles ( Myology ). By Dr.Pardeep Kumar. The General Description of Muscles. Muscular System. The Muscular System. Muscles are responsible for all types of body movement – they contract or shorten and are the machine of the body. Skeletal is a voluntary muscle

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The Muscles ( Myology )

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  1. The Muscles (Myology) By Dr.Pardeep Kumar

  2. The General Description of Muscles

  3. Muscular System The Muscular System • Muscles are responsible for all types of body movement – they contract or shorten and are the machine of the body. • Skeletal is a voluntary muscle • Skeletal muscles share 40% of body weight.

  4. Muscular System Characteristics of Muscles • Muscle cells are elongated (muscle cell = muscle fiber) • Contraction of muscles is due to the movement of microfilaments

  5. Muscular System Skeletal Muscle Characteristics • Most are attached by tendons to bones • Cells are multinucleate • Striated – have visible banding • Voluntary – subject to conscious control • Cells are surrounded and bundled by connective tissue = great force, but tires easily

  6. Muscular System Skeletal Muscles (striated or voluntary muscles) are those which attach to bones and have the main function of contracting to facilitate movement of our skeletons.

  7. Muscular System Structure of skeletal muscle Structure of skeletal muscle

  8. Muscular System Structure of skeletal muscle Structure of skeletal muscle Epimysium:This is the connective tissue wrap just under the deep fascia that surrounds the entire musclePerimysium:This connective tissue surrounds each individual fascicle (bundle of muscle fibers).Endomysium:This is the connective tissue wrapped around each individual muscle cell (fiber). Myofibrils:threadlike fibrils that make up the contractile part of a striated muscle fiber. • Fascia – • on the outside of the epimysium skeletal muscle structure

  9. Muscular System Structure of skeletal muscle Structure of skeletal muscle • Muscle fibers are made up of a group of myofibrils. • Myofibrils contain myofilaments. • The myofibrils have distinct, repeating microanatomical units, termed sarcomeres, which represent the basic contractile units of the muscle fiber/cell (myocyte). • Myofilaments (actin & myosin) • are responsible for muscle • movement.

  10. Muscular System Structure of skeletal muscle • Myofilaments: (Thick and Thin) • Myosin: thick filaments • Actin: thin filaments • A unit of thick and thin filaments is known as a Sarcomere. • These structures hold the key to muscle contraction. The staggered thin and thick filaments has the effect as one might pull a rope towards oneself hand over hand.

  11. Muscular System Structure of skeletal muscle

  12. Muscular System Structure of skeletal muscle

  13. Muscular System Skeletal Muscle Attachments • Epimysium blends into a connective tissue attachment • Tendon – cord-like structure • Aponeuroses – sheet-like structure • Sites of muscle attachment • Bones • Cartilages • Connective tissue coverings

  14. Muscular System Origin and insertion of muscles • Muscles are attached to at least two points • Origin: the point where the tendon attaches to the bone which does not move during muscle action. • Insertion: the point where the tendon attaches to the bone which moves during an action. • e.g. Action of biceps muscle: Scapula is origin (Proximal point) and radius is the insertion. (distal point)

  15. Muscular System Action of skeletal Muscles • Prime mover – muscle with the major responsibility for a certain movement • Antagonist – muscle that opposes or reverses a prime mover • Synergist – muscle that aids a prime mover in a movement and helps prevent rotation

  16. Muscular System Naming of Skeletal Muscles • Direction of muscle fibers • Example: rectus (straight) • Relative size of the muscle • Example: maximus (largest)

  17. Muscular System Naming of Skeletal Muscles • Location of the muscle • Example: many muscles are named for bones (e.g., temporalis) • Number of origins • Example: triceps (three heads)

  18. Muscular System Naming of Skeletal Muscles • Location of the muscles origin and insertion • Example: sterno (on the sternum) • Shape of the muscle • Example: deltoid (triangular) • Action of the muscle • Example: flexor and extensor (flexes or extends a bone)

  19. Muscular System Muscles of Trunk It includes:- Muscles of Back Muscles of thorax Diaphragm Muscles of abdomen

  20. The muscles of back Superficial group • Trapezius • Latissimus dorsi • Levator scapulae • Rhomboideus Major • Rhomboideus Minor

  21. 2.Levator scapular 1.Trapezium Deltoid 3.Rhomboideus Triangle of ausculation 4.Latissimus dorsi Thoracolumbar fascia

  22. Trapezius • Origin – medial 3rd of superior nuchal line of occipital bone • External occipital protuberance • Ligamentum nuchae • Spine of 7th cervicle vertebrae • T1 – T12 spines • Corresponding supraspinatous ligaments • Insertion – Lateral 3rd of clavicle • Acromion & upper lip of crest of spine • Medial end of spine of Scapula • Action – Rotate the scapula during abduction of the arm beyond 90 • Weakness of this muscle leads to dropping shoulder

  23. Muscular System Base of skull (occipital protuberance)

  24. Latissimus Dorsi Origin • posterior part of iliac crest • Spines of lower 6 Thoracic vertebrae • lower 3 or 4 ribs • Lumbar Fascia • Inferior angel of scapula Insertion • floor of the inter tubercular sulcus Nerve Supply – Thoracodorsal nerve Action • It extends, adducts & medailly rotates the arm

  25. Levator Scapulae Origin • Transverse process of upper 4 cervical vertebrae Insertion • Superior angle & Medial border of scapula Nerve Supply • Dorsal scapular nerve • 3rd & 4th cervical nerve Action – Elevation of scapula

  26. Rhomboideus Major • Origin – • 2nd – 5th thoracic spine • I – Medial border of scapula • Nerve Supply – Dorsal scapular nerve • Action – Elevates the medial border & of scapula & pulls it medially

  27. Rhomboideus Minor Origin • Lower part of ligamentum nuchae • Spines of lower 7th cervicle & 1st thoracic vertebrae Insertion • Medial border of scapula Nerve Supply – • Dorsal scapular nerve Action – • Elevates the medial border of scapula & pulls it medially

  28. Triangle of auscultation • Small triangular gap at the back Boundary • Superiorly - Lateral border of Trapezius • Laterally - Medial border of scapula • Inferiorly - Upper border of latissimus dorsi. • Floor is by seventh rib, 6th & 7th intercostal spaces & rhomboideus major.

  29. Clinical Importance of auscultation • Only part not covered by the muscle. • Used to hear the respiratory sounds are better heard with stethoscope • On the Right side – Breadth sound is auscultated • On the Left side – Any kind of Esophageal obstructions can be by auscultation

  30. Muscles of Thorax

  31. The muscles of thorax Extrinsic muscles • Pectoralis major • Pectoralis minor • Serratus anterior Intrinsic muscles • Intercostales externi • Intercostales interni

  32. Pectoralis major • Origin • Anterior surface of medial half of clavicle • Anterior surface of sternum • 6th costal cartilage • Insertion • Crest of great tubercle of Humerus • Action • Adduction • Flexion • Medical rotation

  33. Pectoralis minor(lies deep to pectoralis major) • Origin • Anterior external surface of 3rd to 5th ribs. • Insertion • Coracoid process of scapula • Action • Forward and downward movement of scapula

  34. Serratus anterior • Origin • External surface of upper 8~9 ribs. • Oblique externus abdominis • Insertion • Anterior surface of medical border of scapula

  35. Intercostalesexterni • Origin: lower border of each rib • Insertion: upper border of each rib • Action: elevate the rib (muscles of inspiration) • Replaced anteriorly by external intercostals membrane. Intercostalesinterni • Origin: upper border of rib • Insertion: lower border of rib • Action: depress ribs (muscles of expiration) • Replaced posteriorly by internal intercostals membrane.

  36. Diaphragm Shape and position: dome-shaped between thorax and abdomen, consists of a peripheral muscular part and a central tendon Origin • Sternal part: xiphoid process • Costal part: lower six ribs and costal cartilages • Lumbar part: arises by two crura from upper 2~3 lumbar vertebrae • Insertion: central tendon Weak areas: triangular spaces without muscular tissue • Lumbocostal triangle: between costal and lumbar parts. • Sternocostal triangle: between costal and sternal parts.

  37. Openings in the diaphragm • Aortic hiatus－lies anterior to the body of the 12th thoracic vertebra between the crura. It transmits the aorta, thoracic duct • Esophageal hiatus －for esophagus and vagus nerves at level of T10. • Vena cava foramen －for inferior vena cava, through central tendon at T8 level T8 T10 T12

  38. Action: • Contraction: the dome moving downward, increases the volume of thoracic cavity which results in inspiration, at the same time the intra-abdominal pressure is increased assists in defecation, vomiting or child birth. • Relaxation: the dome returns to the former position, reduces the volume to the thoracic cavity, resulting in expiration.

  39. Muscles of abdomen Anterolateral group • Obliquus externus absominis • Oblequus enternus abdominis • Transversus abdominis • Rectus abdominis

  40. Posterior group • Quadiatus lumborum • Psoas major

  41. Obliquus externus abdominis Origin: external surface of lower 8 ribs. downward, forward and medially (run down and inward) Insertion : iliac crest The lower part of aponeurosis of this muscles forms • Inguinal ligament • Lacunar ligament • Superficial inguinal ring－triangular-shaped defect in aponeurosis of obliquus externus abdominis above pubic tubercle

  42. Obliquus internus abdominis • Deep to obliquus externus abdominis • General direction of fibres: upwards, forwards and medially • Origin: • thoracolumbar fascia • Anterior 2/3rd of iliac crest • Lateral 2/3 of inguinal ligament • Insertion: • Cartilage of 7th to 10th ribs

  43. Transversels abdominis • Deep to obliquus internus • Origin • Inner surface of costal cartilage of lower 6 Ribs. • Thoracolumbar fascia • Iliac crest • Lateral 1/3rd of inguinal ligament • Insertion • Sheath of rectus abdominis • Inguinal falx with aponeurosis of obliquus internus abdominis

  44. Inguinal falx : arch over spermatic cord, inserted with transverses abdominis fiber into medial part of pecten of pubis • Cremaster: around the spermatic cord and testis

  45. Rectus abdominis • Position: lie on to either side of midline • Origin: pubic crest and symphysis • Insertion: xiphoid process and 5th-7th costal cartilages • Has 3-4 tendinous intersections

  46. Similar functions for above four pairs of muscles • Support and compress the abdominal viscera • Increase intra-abdominal pressure, aid in expulsive efforts-vomiting, coughing, sneezing, defecation, urination and childbirth. • Depress ribs, assist in (the act of force(4)expiration. • Flex, lateral flex, and rotate vertebral column

  47. Sheath of rectus abdominis Ant layer－formed by fusion of aponeurosis of obliquus externus abdominis and anterior leaf of aponeurosis of obliquus internus abdominis Post layer • Formed by fusion of posterion leaf of aponeurosis of obliquus internus abdominis and aponeurosis of transverses abdominis • Absent in about 4-5cm below the umbilicus, where aponeuroses of all three muscles form anterior layer the lower free border named arcuate line • Below this line rectus abdominis in contact with transverse fascia

  48. Linea alba －tendinous raphe between right and left recti from xiphoid to pubic symphysis.

  49. Inguinal region Boundaries • Inguinal ligament • Lateral margin of rectus abdominis • A horizontal line stretching from anterior iliac spine to lateral margin of rectus abdominis

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