1. The muscular system
PART A

2. Interactions of Skeletal Muscles
Skeletal muscles work together or in opposition
Muscles only pull (never push)
As muscles shorten, the insertion generally moves toward the origin
Whatever a muscle (or group of muscles) does, another muscle (or group) “undoes

3. Muscle Classification: Functional Groups
Prime movers – provide the major force for producing a specific movement
Antagonists – oppose or reverse a particular movement
Synergists
Add force to a movement
Reduce undesirable or unnecessary movement

4. Muscle Classification: Functional Groups
Fixators – synergists that immobilize a bone or muscle’s origin

5. Names of skeletal muscles
Names give clues to muscle characteristics
Location: femoris, temporalis, etc
Fascicle organization: rectus, oblique, etc
Relative position: profundus, superficialis, etc
Structure: biceps, triceps, etc

6. Names of skeletal muscles
Size: maximus, longus, etc
Shape: trapezius, deltoid, etc
Origin and insertion: sternocleidomastoid, etc
Action: flexor, pronator, etc

7. Organization of skeletal muscle fibers
Parallel muscle
Convergent muscle
Pennate muscle
Unipennate
Bipennate
Multipennate
Circular muscle (sphincter)
Fusiform

8. Arrangement of Fascicles

9. Muscles of the Head

10. Muscles of the Head

11. Muscles of the Head Facial expression muscles Orbicularis oris
O: maxilla and mandible
I: lips
A: compresses lips
Buccinator
I: orbicularis oris
A: compresses the cheek (whistling)

12. Muscles of the Head Occipitofrontalis muscles Occipital
O: occipital bone
I: galea aponeurotic
A: pulls the scalp posteriorly
Frontalis
O: galea aponeurotic
I: skin of the eyebrow
A: raise the eyebrow

13. Muscles of the Head Orbicularis oculi O: frontal and maxillary bones
I: eyelid
A: closes eyes
Corrugator supercilli
O: frontal bone
I: skin of eyebrow
A: draws eyebrow inferiorly and medially

14. Muscles of the Head Levator labii superioris
O: zigomatic and maxilla bone
I: upper lip
A: raises upper lips
Depressor labii inferioris
O: mandible
I: lower lip
A: pulls lower lip inferiorly

15. Muscles of the Head Depressor anguli oris O: mandible
I: angle of mouth
A: pulls corner of mouth down and laterally
Mentalis
I: skin of chin
A: protudes lower lip

16. Muscles of the Head Zigomatics O: zigomatic bone I: corner the mouth
A: smiling muscle
Risorius
O: masseter
I: angle of the mouth
A: pulls corner of lips laterally

17. Muscles of Mastication

18. Muscles of Mastication

19. Muscles of Mastication
Masseter muscles
O: zigomatic and maxilla bones
I: mandible
A: closes the jaw
Temporalis muscles
O: temporal fossa

20. Muscles of Mastication
Pterygoids
O: sphenoid, palatine and maxillary bones
I: mandible
A: elevates mandible
Buccinator

21. Extrinsic muscles of the eye

22. Extrinsic muscles of the eye
Inferior and superior rectus muscles
Lateral and medial rectus muscles
Inferior oblique muscles
Elevates the eye and turns it laterally
Superior oblique muscles
Depresses the eye and turns it laterally

23. Summary of Cranial Nerves and Muscle Actions
Figure 15.3c

24. Muscles of the Neck

25. Muscles of the Neck

26. Muscles of the Neck Platysma O: fascia of chest and deltoid
I: mandible, skin, corner of the mouth
A: depresses mandible, pulls lip back and down
Sternocleidomastoid
O: manubrium and clavicle
I: temporal and occipital bones
A: flexion forward of the neck

27. Muscles of the Neck Scalenes – anterior, middle, posterior
O: cervical vertebrae
I: first 2 ribs
A: elevates first 2 ribs
Digastric
O: mandible and mastoid process
I: hyoid
A: elevates hyoid bone

28. Muscles of the Neck Mylohyoid O: mandible I: hyoid bone
A: elevates hyoid bone
Sternohyoid
O: manubrium and clavicle
A: depresses hyoid bone

29. Muscles of the Thorax Muscles inserting on the scapula:
Rhomboid muscles
O: vertebrae
A: adducts and stabilizes scapula
Levator scapulae muscles
A: elevates scapula

30. Muscles of the Thorax

31. Muscles of the Thorax Abductors of the shoulder joint:
Deltoid muscles (major abductor)
O: clavicle and scapula
I: humerus
Supraspinatus muscles
O: scapula

32. Muscles of the Thorax

33. Muscles of the Thorax Lateral rotation of the shoulder joint:
Infraspinatus muscles
O: scapula
I: humerus
Teres minor muscles

34. Muscles of the Thorax Medial rotators of the shoulder joint
Teres major muscles
O: scapula
I: humerus (anterior surface)

35. Muscles of the Thorax

36. Muscles of the Thorax Origin on the ribs and insertion on the scapula:
Serratus anterior muscles
A: fixates, protracts the scapula
Pectoralis minor muscles
A: ribs fixed: moves scapula forward and inferiorly and with scapula fixed it moves up the rib cage

37. Muscles of the Thorax

38. Muscles of the Thorax Flexion of the shoulder joint (agonist):
Pectoralis major muscles
O: clavicle, sternum, ribs, external oblique muscle
I: humerus
Extension of the shoulder joint (agonist):
Latissimus dorsi muscles
O: vertebrae, ribs, ilium

39. Muscles of the Thorax

40. Muscles of the Thorax

41. Muscles of respiration
External intercostal
O: rib above
I: rib below
A: elevates rib cage
Internal intercostal
O: rib below
I: rib above
A: depresses rib cage

42. Muscles of Respiration

43. Muscles of Respiration

44. Muscles of Respiration
Diaphragm
O: ribs and its cartilage, sternum, vertebrae
I: central tendon of the cartilage
A: prime action in inspiration

45. Muscles of Respiration

46. Muscles of the Abdomen Rectus abdominis O: pubis
I: xiphoid process, ribs
A: flexes vertebral column,increase abdominal pressure
External oblique
O: ribs
I: linea alba, ilium
A: see above, helps trunk rotation and lateral flexion

47. Muscles of the Abdomen Internal oblique
O: lumbar fascia, ilium, inguinal ligament
I: linea alba, pubis, ribs
A: same as external oblique
Transversus abdominis
O: ribs, inguinal ligament, ilium, lumbar fascia
I: linea alba, pubis
A: compresses abdominal content

48. Muscles of the Abdomen

49. Muscles of the Arm

50. Muscles of the Arm Biceps brachii muscle O: scapula, shoulder joint
I: radius
A: agonist flexor of the elbow
Brachioradialis
O: humerus
A: synergists for flexion of the elbow

51. Muscles of the Arm Brachialis O:humerus I: ulna
A: synergist for flexion of the elbow

52. Muscles of the Arm
Triceps brachii muscle (long, lateral and medial heads)
O: scapula, humerus
I: ulna
A: agonist extensor of the elbow

53. Muscles of the Arm

54. Rotator Cuff Muscles
supraspinatus, infraspinatus, teres minor, and subscapularis
Function mainly to reinforce the capsule of the shoulder
Secondarily act as synergists and fixators

55. Rotator Cuff Muscles

56. Rotator Cuff Muscles

57. Muscles of the forearm Flexion of the wrist (O: humerus)
Flexor carpi ulnaris
I: metacarpus and carpus
Flexor carpi radialis
I: metacarpals
Palmaris longus
I: palm of the hand

58. Muscles of the forearm

59. Muscles of the forearm Extension of the wrist (O: humerus)
Extensor carpi radialis
I: metacarpus
Extensor carpi ulnaris

60. Muscles of the forearm

61. Muscles of the forearm Pronation of the forearm (I: radius)
Pronator teres muscle
O: humerus

62. Muscles of the forearm

63. Muscles that move the hand

64. Muscles that move the hand

65. Muscles of the pelvis and lower limb
Gluteal muscles (O: ilium; I: femur)
Gluteus maximus
A: extension and lateral rotation of thigh
Gluteus medius and minimus
A: abduction and medial rotation of thigh

66. Muscles of the pelvis and lower limb

67. Muscles of the pelvis and lower limb
Sartorios
O: ilium
I: tibia
A: flexes the thigh and helps in crossing the leg
Adductors of the leg
O: pubis
I: femur

68. Muscles of the pelvis and lower limb
Gracilis
O: pubis
I: tibia
A: adducts, flexes and medially rotates the thigh

69. Muscles of the pelvis and lower limb

70. Iliopsoas muscle
Formed from the merging of the psoas major and the iliacus muscles
O: ilium, vertebrae
I: femur
Flexor of the trunk, flexor of the leg

71. Muscles of the pelvis and lower limb

72. Muscles of the leg Quadriceps (I: tibia; A: extends the knee)
Rectus femoris
O: ilium
Vastus medialis, intermedius, lateralis
O: femur

73. Muscles of the leg

74. Muscles of the leg Tensor fasciae latae O: ilium I: fasciae latae
A: flexes, abducts the thigh; tenses the fasciae latae

75. Muscles of the leg
The hamstrings (O: ischium; I: tibia; A: extend thigh, flexes knee)
Biceps femoris muscles
Semimembranosus muscles
Semitendinosis muscles

76. Muscles of the leg

77. Muscles of the leg Plantar flexion (I: calcaneal tendon)
Gastrocnemius muscle
O: femur
Soleus muscle
O: fibula and tibia
Eversion and plantar flexion
Fibularis muscle
O: fibula
I: foot

78. Flexors of the knee Popliteus muscle O: femur I: tibia
A: unlocks the knee joint

79. Muscles of the leg

80. Muscles of the leg Tibialis anterior O: tibia
I: metatarsal and cuneiform bones
A: dorsiflexion of the foot
Tibialis posterior
I: tarsal and metatarsal bones
A: foot inversion

81. Muscles of the leg

82. Muscles of the leg

83. Muscles That Move the Toes
Extensors digitorum
O: Tibia, fibula
I: Digits
A: Extends the digits