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

8. Structure of skeletal muscle Structure of skeletal muscle
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 muscle Perimysium: 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

10. Structure of skeletal muscle Structure of skeletal muscle
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.

11. Structure of skeletal muscle
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.

12. Structure of skeletal muscle
Muscular System
Structure of skeletal muscle

13. Structure of skeletal muscle
Muscular System
Structure of skeletal muscle

14. 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

15. Origin and insertion of muscles
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)

16. 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

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

18. 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)

19. 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)

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

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

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

23. 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

24. Muscular System
Base of skull
(occipital protuberance)

25. 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

26. 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

27. 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

28. 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

29. 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.

30. 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

31. Muscles of Thorax

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

33. Pectoralis major Origin Insertion Action
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

34. 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

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

36. Origin: lower border of each rib Insertion: upper border of each rib
Intercostales externi
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.
Intercostales interni
Origin: upper border of rib
Insertion: lower border of rib
Action: depress ribs (muscles of expiration)
Replaced posteriorly by internal intercostals membrane.

37. Diaphragm Shape and position: Origin
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.

38. 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

39. 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.

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

41. Posterior group
Quadiatus lumborum
Psoas major

42. 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

43. 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

44. 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

45. 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

46. 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

47. 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

48. 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

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

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

51. Descent of testes Seven-week embryo showing the
testis before its descent from the
dorsal abdominal wall

52. Fetus at 28 week the testis passing
through the inguinal canal

53. Newborn

54. Inguinal canal
Position: oblique passage, 4cm long, located 1.5cm above medial half of inguinal lig.

55. Boundaries Ant wall Aponeurosis of obliquus externus abdominis
Obliquus internus abdominis (lateral third of wall)

56. Post wall
Transverse fascia
Inguinal flax medially
Roof－arched lower fibers of obliquus internus and transversua abdominis
Floor－inguinal lig．

57. Two openings Superficial inguinal ring
Deep inguinal ring －defect in transverse fascia 1.5cm above midpoint of inguinal ligament

58. Structures passing through the inguinal canal
Spermatic cord and ilioinguinal nerve in males
Round ligament of uterus and ilioinguinal nerve in females

59. Inguinal Triangle (of Hesselbach)
Boundaries
Inguinal ligament inferiorly
Lateral border of rectus abdominis medially
Inferior epigastric artery laterally

60. THANK
YOU
VERY
MUCH