Muscles

1. A Interactive Apporach Of Muscles
(Complete Info ppt.)
By- Dr. Armaan SinghBy- Dr. Armaan Singh

2. Muscle Strains
 Tend to occur at the
musculotendinous junction
 At the muscle fibers
 At the tendon or tenoperiosteal
junction
 It is essential to know the origin and
insertion of a muscle, to assess it
correctly
 Passively stretching the muscle
 Testing its isometric, concentric and
eccentric contractions

3. Types of Muscle
 Voluntary muscle
 Striated: somatic nerves
 Involuntary: smooth
 Autonomic system
 Cardiac muscle
 Autonomic system

4. Voluntary Muscle
Consists of contractile element
 Muscle fibers which develop tension
 Non-contractile, connective tissue, of
which the tendon forms a major part
 Connective tissue transmits the force of
the muscle to the bones
 Helps protect the muscle tissue and
binds muscle fibers together
 Muscle fibres are grouped into bundles
called fasciculi

5. Muscle Fibres
 Are grouped into bundles called
fasciculi
 The size of fasciculi varies
 Muscles performing gross movements
have a larger number of fibres in each
fasciculus

6. Muscle Fibres
 Muscles performing fine movements have smaller
fasciculi
 Supplied by a greater number of nerve fibres

7. Fasciculi
 Arrangement of the fasciculi
determines the shape of the
muscle
 Amount of tension
 Speed of contraction
 Fasciculi contain fibres that are
either parallel or oblique

8.  An individual muscle cell is called a
muscle fibre
 Sarcoplasma is the cytoplasm of the
muscle fibre
 It is enclosed by the sarcolemma, a
plasma membrane
 Sarcoplasm contains
T- tubules which transport
substances
 Sarcoplasmic reticulum stores
calcium
Muscle Fibres

9. Myofibrils
 Myofibrils are made up of
sarcomeres
 Smallest functional unit of a
muscle
 Sarcomere is composed of
filaments of myosin and actin
responsible for contraction
 Myosin is thick filament
 Actin is thin filament
 Tropomyosin and troponin are
attached to Z-disc

10. Muscle
 Epimysium around muscle
 Perimysium around fasciculi
 Endomysium around muscle cell
 Bundles of muscle cells or fibre
 Myofibril consists of myofilament
actin myosin filament

11.  Muscle belly with two tendons
 Two heads : biceps
 Three heads : triceps
 Four heads : quadriceps
Muscle Types

12.  Short muscle fibres are connected
together by tendinous intersections.
 They develop from myotomes
 Have a segmental nerve and blood
supply
 Each segment has a short range of
contraction
 The range of the muscle is the sum of
the segments
 e.g. rectus abdominus muscle or
sternomastoid
Parallel Fibres

13.  Long muscle fibres are found in strap
muscles
 They can shorten a great deal
 Producing a large range of movement,
e.g. the sartorius
Parallel Fibres

14. Oblique Fibres Pennate Muscles
 Unipennate – muscle fibres are
confined to one side of the tendon,
e.g. unipennate lumbrical from
flexor pollicis longus
 Bipennate – fibres on both sides of
the tendon, e.g. bipennate
lumbrical, rectus femoris
 Multipennate – muscle fibres attach
and converge on several tendons
e.g. deltoid

15. Sphincter
 Circular fibres, true sphincter has no bony
attachments
 Deep portion of external anal sphincter

16.  Muscle can only act on a joint, if it
crosses the joint
 Muscles that have a common action on
the joint, tend to have same nerve
supply
 Exception, flexors of the elbow, have
several different nerves
 Nerve supplying the muscle, gives an
articular branch to joint
Muscles

17.  Tendons, consist of type I collagen
 Form a connection between the
muscle belly and its attachments
Tendon

18. Musculotendinous Junction
 Junctional area between muscle
and tendon
 Growth plate of muscle
 Subjected to great mechanical
stress
 Muscles tend to tear at
musculotendinous junction

19. Muscle Attachments
 Muscles are attached to bone by
tendons
 There is a gradual transition from
tendon to fibrocartilage to lamellar
bone via the periosteum
Benjamin & Ralphs, 1986; Benjamin et al., 1996

20. Osteotendinous Junction
 Four zones
 Pure fibrous tissue
 Unmineralised fibro-cartilage
 Mineralised fabricating
 Bone
Benjamin et al., 1986

21. Force of Muscle
 The force of a muscle depends
on its physiological cross-section
area
 Strap muscles are weaker than
pennate muscles

22.  Some muscles cross two joints
 Hamstrings:
semi-membranosus,
semitendinosus, long head of
biceps femoris
 Medial and lateral heads of
gastrocnemius, plantaris
 Rectus femoris portion of
quadriceps
 More likely to be injured
Muscles

23. Muscle Tears

24. Muscle Tears

25. Skeletal Muscle Action
 No muscle acts alone
 Muscles usually act in groups
 The major muscle which initiates
movement, is called the agonist (prime
mover)
 Antagonists have the opposite action
 Synergist muscles act as stabilisers or
fixators

26.  Synergists help to steady the
part being moved
 Fixators stabilise the attachment
of the prime mover
 Enable it to work more efficiently
 Flexing the elbow, brachialis is
the prime mover
 Biceps brachii and the brachioradialis are synergists
 Fixators are muscles around the shoulder joint; the rotator cuff
muscles stabilise the head of the humerus
Muscle Action

27. Muscles
 Muscles develop from mesoderm
 Myotomes are a group of voluntary
muscles supplied by a specific nerve root
 A dermatome is an area of skin supplied
by a specific nerve root
 They generally tend to follow the
segmental supply of the underlying
muscles

28. Myotomes
 Four consecutive spinal segments
 Control each lower limb joint
 Hip L2,3,4,5
 Knee L3,4,5, S1
 Ankle L4,5, S1,2

29. Myotomes
 Flexion of hip
 Iliopsoas L2,3
 Extension of hip mainly gluteus
maximus and hamstrings, L4,5
 Extension of knee
 Quadriceps L3,4
 Flexion of knee L5, S1

30. Myotomes
 Dorsiflexion of ankle
tibialis anterior (TA) L4,5
 Extensor hallucis longus
L5
 Plantar flexion of ankle
 Posterior muscles of calf
S1,2

31.  Inversion and dorsiflexion
 Tibialis anterior L4 inversion and
plantar flexion
 Tibialis posterior L4
Inversion

32. Plantar flexor and evertor
 Peroneus longus
 Peroneus brevis L5,S1
Dorsiflexor and evertor
 Peroneus tertius L5,S1
Evertors

33.  Skin
 Bones
 Muscles / tendons
 Nerves
 Blood vessels
Dermatomes

34. Dermatomes Lower Limb

35. Types of Muscle Action

36. Voluntary Muscle Action
Three types
 Isometric
 Concentric
 Eccentric

37. Isometric Action
 No change in the length of
the muscle fibres
 Increase in tension
 Least stress to the muscle
 First phase in the
rehabilitation of a muscle tear
or strain

38. Isometric Action
 Isometric produces an
increase in strength only at
the joint angle at which it is
performed
 It should only be done for
short periods
 Muscle fatigue due to
restriction of the blood supply

39.  The origin and insertion move
towards each other
 The muscle shortens as it
increases its tension
 It is the traditional action in
books
 Second phase of the rehabilitation
of a muscle
 Pulling up on a bar
 Elbow flexors work concentrically
Concentric Action

40.  Muscle lengthens as it develops
tension
 Elbow flexors when lowering
yourself from a bar
 Eccentric action is the most
powerful action
 It is the most stressful
 The last phase in muscle
rehabilitation
Eccentric Action

41. Musculoskeletal Injuries
Extrinsic factors
Sport
Contact sports
Environment
Equipment
Protective
Overuse
Intrinsic factors
Physical
Physiological
Psychological
Previous Injury
Inadequate rehabilation

42. Muscle Injuries
 Damage to muscle fibres heal relatively
quickly because of their rich blood
supply
 If tendons are damaged, healing is
slower due to their relatively poor blood
supply
 If the injury is close to the bone, e.g. a
blow to the vastus intermedius
 May develop myositis ossificans
 These injuries usually take
longer to heal

43. Muscle
 Pre-stretching the muscle prior to a
concentric muscle action
 Increases the force because of elastic
recoil
 Long jumpers stretch the extensor
muscles in the downward sink on to the
board before take-off
 Wind-up or cocking phase in bowling a
ball in cricket
 If it is stretched more than 120% then
its force of contraction decreases