1. Anatomy of the muscular system
Ch. 10
Anatomy of the muscular system

2. The incredible human machine

3. Introduction Myology - Study of muscles
Energy for Muscular contraction - ATP
Three types of muscle - skeletal, cardiac, smooth
Number of skeletal muscles - more than 600
Weight of muscles %

4. Full muscular system

5. Connective Tissue coverings
Fascia - surrounds and separates muscles
Tendons - connects muscle to bone
Aponeurosis - broad sheet of connective tissue
Epimysium - covers whole muscle
Perimysium - covers fascicles
Endomysium - covers myofibrils

6. Structure Size - range from small to large
Shape -broad, narrow, short, long
Arrangement
Parallel, converging, oblique, pennate, bi- pennate, sphincter

7. Attachment of muscles Origin - attachment to immovable bone
Insertion - attachment to movable bone

8. Muscle actions Prime movers (agonists) - main action
Antagonists - opposite action
Synergists - helper muscle

9. The power of muscle

10. Lever systems Bones serve as levers and joints serve as fulcrums
Contracting muscles applies pulling force on bone lever
Four components of lever system
Rigid bar - bone
Fulcrum - joint
Load - what is moved
Pull - muscle contraction

11. How muscles are named Latin based or English
Naming - supply hints as to muscle action
Location, function, shape
Direction of fibers
Number of heads
Points of attachment
Relative size

12. Muscles of facial expression
Epicranius - raises eyebrows
Orbicularis oculi - closes eye
Orbicularis oris - draws lips together
Buccinator - smiling
Zygomaticus - laughing

13. Muscles of mastication - chewing
*Masseter - closes jaw
Temporalis - closes jaw

14. Muscles that move the head
*Sternocleidomastoid - flexes head
*Splenius capitis - extends head
Semispinalis capitis - extends head

15. Muscles of the thorax *Intercostals - lift ribs
*Diaphragm - enlarges thorax

16. Muscles that move the shoulder girdle
*Trapezius - raises shoulders
Rhomboideus major - rotates/retracts scapula
Levator scapulae - elevates/retracts scapula
Serratus anterior - pulls shoulder down and forward
*Pectoralis minor - pulls shoulder down

17. Muscles that move the upper arm
Flexors
Coracobrachialis - adduction
*Pectoralis major - flex upper arm
Extensors
Teres major - extension, medial rotation
*Latissimus dorsi - extends upper arm
Abductors
Supraspinatus
*Deltoid
Rotators - *rotator cuff
Subscapularis- medial rotation
Infraspinatus - outward rotation
Teres minor - outward rotation

18. Muscles that move the forearm
Flexors
*Biceps brachii
Brachialis
Brachioradialis
Extensor
*Triceps brachii

19. Muscles that move the hand
Flexors
Flexor carpi radialis and ulnaris
Palmaris longus
*Flexor digitorum profundus
Extensors
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor carpi ulnaris
*Extensor digitorum

20. Muscles of the abdominal wall
*external and internal obliques - compresses abdoment - allows for side to side motion
*Rectus abdominis
Flexes waist
Transverse abdominus synergist Compresses abdomen

21. Muscles of the back *Trapezius *Rhomboideus Infrapinatus
Extends head/neck
*Rhomboideus
Retracts scapula
Infrapinatus
Extends/rotate arm
Teres major and minor
Extends, adduts arm
*Latissimus dorsi - extends
arm

22. Muscles of the pelvic floor
Levator ani
Superficial transversus perinei
Bulbospongiosus
Ischiocavernoses

23. Muscles that move the thigh
Anterior group
*Psoas major
Iliacus
Posterior group
*Gluteus maximus, medius, minimus
Tensor fasciae latae
Adductors
Adductor longus
Adductor magnus
Gracilis

24. Muscles that move the leg
Flexors
*Biceps femoris
Semitendinosus
Sartorius
Extensor
*Quadriceps femoris group
Rectus femoris
Vastus lateralis/medialis/intermedius

25. Muscles that move the ankle foot and toes
Dorsal flexors
*Tibialis anterior
Peroneus tertius
Exensor digitorum longus
Plantar flexors
*Gastrocnemius
Soleus (synergist)
Flexor digitorum longus

26. Ch. 11 The physiology of the muscular system

27. Introduction
Purpose - move framework of body, produce heat, facilitate posture
Characteristics
Excitability - ability to be stimulated
Contractibility - ability to shorten producing movement
Extensibility - ability to stretch and return to resting length.

28. Structure of muscle fibers
Description - each fiber - muscle cell (spans a joint)
Sarcolemma - cell membrane
Sarcoplasm - cytoplasm of muscle cell
Contains mitochondria, nuclei, myofibrils
Myofibrils - filaments
Myosin - thick
Actin - thin
Sarcomere - unit within myofibril
Extends from z line to z line.
Z lines produce striations
Sarcoplasmic reticulum (endoplasmic reticulum)
Contains transverse tubules (nerve impulse)

29. Neuromuscular Junction
Where neuron and muscle fiber meet.
Abundant mitochondria present for ATP production
Neurotransmitters - chemical communicators located at the end of neuron in the Cytoplasm
Motor Unit
Mucle fibers contract at once when triggered by neurotransmitters
Recruitment - increase in number of motor units activated.

30. Skeletal Muscle Contraction
Shortening of sarcomeres results in muscle pulling against attachments
Myosin - two twisted strands with crossbridges
Actin contains myosin binding sites
Sliding filament theory
Myosin cross-bridge attaches to binding site on actin filament and bends
Pulls actin filament, releases and attaches to next binding site, pulling again.
Energy from atp used to prepare the cross-bridges.

31. Stimulus for contraction
Neurotransmitter - Acetylcholine released from synaptic vesicles at end of axon of neuron.
Note - botulinus toxin prevents acetylcholine release.
Receptors detect neurotransmitter
Impulse spreads over sarcolemma then travels through transverse to sarcoplasmic reticulum
Calcium released by sarcoplasmic reticulum
High calcium moves Troponin and tropomyosin aside, exposing binding site
Myosin Crossbridge attaches to binding site
Crossbridge shortens pulling filaments across each other
Sarcomere shortens
Acetylcholinesterase decomposes acetylcholine
Calcium returns to sarcoplasmic reticulum
Link between actin and myosin is broken.
Note - rigor mortis - lack of ATP - prevents muscle relaxation.

32. Muscle contraction

33. Oxygen supply and cellular respiration
During rest - enough oxygen to support aerobic cellular respiration.
Oxygen deficiency during exercise
Lactic acid end product of anaerobic respiration. - lactic acid diffuses out of muscle cells and is carried to liver.
Oxygen debt - amount of oxygen that liver cells require to convert lactic acid into glucose plus amt. muscle cells need to make atp to original concentration.
Muscle fatigue-muscle loses ability to contract during strenuous exercise.
Result of lactic acid accumulation (lower ph)
Muscle cramp - lack of ATP required to return calcium ions back to sarcoplasmic reticulum so muscle fibers can relax.
Heat production - energy produced by cellular respiration is lost as heat.

34. Muscular responses
One method of studying muscle function - remove single fiber and connect to device that records response to electrical stimuli.
Muscle fibers remain unresponsive till they reach Threshold stimulus (stimulus of a certain strength)
All or none response
Summation - series of stimuli of increasing frequency
Recruitment of motor units-increase in number of activated motor units
Sustained contractions - muscle tone - achieved by continuous state of sustained contraction.
Treppe-staircase phenomenon - twitch contractions 1 second apart
Tetanus-multiple wave summation/no relaxation

35. Recording a muscular contraction
Myogram - recording of electrically stimulated muscle contraction
Myograph - machine that records the contraction
Twitch-single short contraction
Latent period - time delay followed by period of contraction and relaxation.

36. Muscle tone
Tonic contraction-continual partial contraction of a muscle
Flaccid - less tone than normal
Spastic-more tone than normal
Negative feedback mechanism controls tone
Graded strength - affected by:
Metabolic condition of fibers
Number of fibers contracting
Number of motor units recruited

37. Physical training
Strength training- results in hypertrophy - enlargement of fibers
Endurance training - increases ability to sustain moderate contractions for longer time. Increase of mitochondria.
Atrophy - result of disuse
Decreased capillary networks, decreased mitochondria, decreased filaments.

38. Smooth muscle Fibers - elongated with tapered ends Lack striations
Undeveloped sarcoplasmic reticulum
Located in iris of eye and walls of hollow organs
Display rhythmicity - allow for peristalsis
Contraction uses acetylcholine and norepinephrine
Slower to contract and relax but can contract longer

39. Cardiac muscle Mechanism - same as smooth and skeletal
Difference: transverse tubules supply extra calcium allowing for contraction for longer periods.
Structure
Intercalated discs - join cells and cause cells to contract as a unit.
Rythmic
Self-exciting