anatomy lecture of skull and bones of hu

anatomy

1. The muscle Presented by: Syed Zain Ul Abidin (PT) DPT, MSPT, CHR

2. Objectives What are the muscles Basic function of muscles Difference between the basic 3 types of muscles How muscle contraction occur Types of muscles according to Fasciculi Arrangement

3. Introduction Muscle is a contractile tissue that produces movement. The muscle is derived from MUS which means mouse. They are named so because they resemble a mouse. They are the motors of the body.

4. Functions of muscle Movement Stability Heat production Control of body openings and passages

5. Classification of muscles Striated muscles Non striated muscles

6. Striated muscles These muscles have characteristic light and dark bands. These muscles are present in limbs, body walls, tongue, pharynx and beginning of esophagus. These can be multinucleated or uninucleated. Striated muscles can be voluntary or involuntary. These muscles contract rapidly.

7. Striated muscles 1. Skeletal muscles Skeletal muscles are attached to the bones , it is responsible for skeletal movements. The peripheral portion of the central nervous system (CNS) controls the skeletal muscles. These muscles are under conscious, or voluntary, control. The basic unit is the muscle fiber with many nuclei.

8. Makes the flesh or meat of animals. Nerve supply is from motor nerve which is mixed nerve consisting of motor and sensory fibers. Muscle spindles These muscle fibers are striated (having transverse streaks) and each acts independently of neighboring muscle fibers.

9. 2. Cardiac muscle It is found in the walls of the heart Works under the control of the autonomic nervous system. The cardiac muscle cell has one central nucleus, like smooth muscle but it also is striated, like skeletal muscle. The cardiac muscle cell is rectangular in shape. The contraction of cardiac muscle is involuntary, strong, and rhythmical.

10. NON-STRAITED Smooth Muscle Found in the walls of the hollow internal organs such as blood vessels, the gastrointestinal tract, bladder, and uterus It is under the control of the autonomic nervous system. Smooth muscle cannot be controlled consciously and thus acts involuntarily. The non-striated (smooth) muscle cell is spindle-shaped Has one central nucleus Smooth muscle contracts slowly and rhythmically.

11. These muscles have no light and dark bands. They are involuntary muscles and make the walls of blood vessels and present in esophagus, urogenital tract, urinary bladder, iris of eye, arrector pilli muscle. The cells of these muscles are uni -nucleated..

12. Two parts: Fleshy part Fibrous part

13. Structure of muscle Epimysium Perimysium Endomysium

14. Structure of a muscle

15. Tendon Skeletal muscle Epimysium Perimysium Muscle fasciculi Muscle bundle Endomysium

16. Each muscle is composed of muscle fasciculi which are bundles of muscle fibers . Muscle fibers are multinucleated, cross striated cylindrical cells. Cell membrane sarcolemma Cytoplasm sarcoplasm The sarcoplasm contains nuclei and myofibrils. Nuclei are arranged around the periphery and myofibrils are scattered in the sarcoplasm. Myofibrils have dark and light bands. A – band, I – band, Z – discs

17. Structure of myofibril Composed of myofilaments. Myofilaments are of two types ; Thin or actin filaments Thick or myosin filaments Actin two strands of G-actin twisted in helical manner. Tropomyosin and troponin.

18. Myosin light and heavy chains

19. SLOW AND FAST MUSCLE FIBERS Type 1 (slow fibers) Present in postural muscles. These are red in color because of large amounts of myoglobin. Fatigue resistant.

20. TYPE 2 (FAST FIBERS) Present in the muscles required for body movements These are paler in color because of small amounts of myoglobin Fatigue easily. INTERMEDIATE FIBERS Type of fast fibers which are resistant to fatigue.

21. Classification of skeletal muscles According to fascicular architecture According to function

22. ACCORDING TO FASCICULAR ARCHITECTURE Parallel fasciculi Oblique fasciculi Spiral fasciculi

23. Parallel fasciculi The muscle fasciculi are arranged parallel to the line of pull. This type of muscles are more concerned to the movements. The muscles can be ; Quadrilateral ( thyrohyoid ) Strap like ( sartorius ) Strap like with tendinous intersections (rectus abdominis) Fusiform (digastric and biceps)

24. Oblique fasciculi In these muscles, muscle fasciculi are arranged obliquely to the line of pull. These muscles are more powerful than muscles with parallel fasciculi. These muscles can be; Triangular ( temporalis) Unipennate (extensor digitorum longus) Bipennate ( rectus femoris) Multipennate (deltoid) Circumpennate (tibialis anterior)

25. Spiral fasciculi Spiral fibers are found in trapezius, pectoralis major, latissmus dorsi etc. In cruciate muscles, fasciculi are crossed.

26. NOMENCLATURE

27. Muscles are named according to: 1. ACCORDING TO THEIR SHAPE: e.g. deltoid (triangular), trapezius, rhomboids (diamond shaped), serratus anterior (Fig. 4.10), latissimus dorsi , quadratus (quadrangular), teres (round) teres major etc .

28. 2. ACCORDING TO THE NUMBER OF HEADS OF ORIGIN B iceps (two heads ): biceps brachii T riceps (three heads): triceps brachii Q uadriceps (four heads): Quadriceps Femoris Digastric (two bellies): anterior and posterior bellies of digastric

29. 3. ACCORDING TO THEIR GROSS STRUCTURE: semitendinosus , semimembranosus, etc. (Fig. 4.12).

30. 4. ACCORDING TO THEIR POSITION: S upra (above): supraspinatus Infra (below): infraspinatus Anterior (front): Tibialis anterior Posterior (back): Tibialis Posterior

31. 5. According to their attachments, e.g. stylohyoid , cricothyroid , sternocleidomastoid (from sternum and clavicle to mastoid process) ( Fig. 4.14), etc

32. 6 . According to their action, e.g. adductor longus , flexor carpi ulnaris (Fig. 4.15), abductor pollicis longus , etc. orbicularis oculi

33. 7. According to direction of their fibres, e.g. rectus abdominis , transversus abdominis , orbicularis oculi (Fig. 4.7).

34. 8. A muscle with two bellies with an intervening tendon is called digastric muscle (Fig. 4.7). Muscle with number of intervening tendons or intersections is the rectus abdominis .

35. 9. According to the size: Major (big): pectoralis major Minor (small) : pectoralis minor Longus (long): adductor longus Brevis (small): abductor pollicis brevis

36. 10. According to the depth: Superficialis (superficial): flexor digitorum superficialis Profundus (deep): flexor digitorum profundus Externus (external): external oblique of the anterior abdominal wall Internus (internal): internal oblique of the anterior abdominal wall flexor digitorum profundus

37. NERVE SUPPLY OF SKELETAL MUSCLE 1. Motor fibres (60 %) 2. Sensory fibres (40 %) Muscle spindles are spindle-shaped sensory end organs of the skeletal muscle. Each spindle contains 6-14 intrafusal muscle fibres which are of two types, the larger nuclear bag fibres, and the smaller nuclear chain fibres (Fig. 4.16)

38. Motor point : It is the site where the motor nerve enters the muscle. Motor unit: A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals. Groups of motor units often work together to coordinate the contractions of a single muscle Small motor units (5-10 muscle fibres) are found in muscles of fine movements ( extraocular muscles ). Large motor units (100-2000 muscle fibres) are found in muscles of gross movements (proximal limb muscles).

39. Motor pool : All of the motor units within a muscle are considered a motor pool. Composite/hybrid muscle : Muscle supplied by two different motor nerves with different root values is called a composite or hybrid muscle, e.g. adductor magnus , flexor digitorum profundus and pectoralis major. Adductor Magnus has an adductor part supplied by obturator nerve and a hamstrings part supplied by sciatic nerve.

40. Nerve Supply of Smooth Muscle Single-unit type : Impulse reaches one muscle cell and is transmitted to others Multi-unit type : Each muscle cell receives separate nerve fibre. Nerve Supply of Cardiac Muscle Heart is supplied by sympathetic and parasympathetic nerve fibres.

41. ACTIONS OF MUSCLES I sotonic contraction: During contraction the length of the muscle may decrease. I sometric contraction: During contraction the length of the muscle May remain unchanged. Eccentric: Length may increase, according to the functional demands of the body . Concentric: When there is increasing tension in the muscle as it contracts and shortens.

42. Each movement at a joint is brought about by a coordinated activity of different groups of muscles. These muscle groups are classified and named according to their function . Prime movers (agonists) bring about the desired movement . Antagonists (opponents) oppose the prime movers . Fixators are the groups of muscles which stabilize the proximal joints of a limb, so that the desired movement at the distal joint may occur on a fixed base. Synergists: Two or more muscles causing one movement are synergists.