THE MUSCULAR SYSTEM

1. THE MUSCULAR SYSTEM

2. INTERACTIONS OF SKELETAL MUSCLES IN THE BODY • Muscles only pull; they are not capable of pushing • The muscle that provides the major force for the specific movement is called the prime mover or the agonist • Muscles that oppose or reverse a particular movement are called the antagonists • Synergists help the prime movers by adding extra force to the same movement, or by reducing undesirable or unnecessary movement

3. NAMING SKELETAL MUSCLES • Some muscle names indicate the bone or body region with which the muscle is associated • Some muscles are named for their shape • Terms such as maximus, minimus, longus, and brevis are often used in muscle names to indicate relative size of the muscle • The names of some muscles indicate the direction in which their fibers run in relation to an imaginary line of the body, such as the midline • The number of origins a muscle has may be indicated by the word biceps, triceps, or quadriceps • Some muscles are named according to the location of their origin and insertion • A muscle may be named for its action by using a word such as flexor or extensor in its name

4. MUSCLE MECHANICS:IMPORTANCE OF FASCICLE ARRANGEMENT AND LEVERAGE • In skeletal muscles the common arrangement of the fascicles varies, resulting in muscles with different shapes and functional capabilities • The fascicular pattern is circular when the fascicles are arranged in concentric rings • A convergent muscle has a broad origin and its fascicles converge toward a single tendon of insertion • In parallel arrangement, the long axis of the fascicles runs parallel to the long axis of the muscle • A spindle-shaped parallel arrangement of fascicles is sometimes classified as a fusiform muscle • In a pennate pattern of arrangement the fascicles are short and attach obliquely to a central tendon that runs the length of the muscle

5. FASCICLE ARRANGEMENT TO MUSCLE STRUCTURE

6. MUSCLE MECHANICS:IMPORTANCE OF FASCICLE ARRANGEMENT AND LEVERAGE • The operation of most skeletal muscles involves the use of leverage and lever systems, partnerships between the muscular and skeletal systems • A lever is a rigid bar that moves on a fixed point, or a fulcrum, when a force is applied to it • The applied force, or effort is used move a resistance or load • In your body, your joints act as the fulcrums, the bones as the levers, and the muscle contraction as the effort • There are three types of levers: • First-class • Second-class • Third-class

7. MUSCLE LEVERAGE

8. MUSCLE LEVERAGE

9. ANTERIOR SUPERFICIAL MUSCLES

10. DIAGRAMMATIC VIEW OF ANTERIOR MUSCLES

11. POSTERIOR VIEWOF SUPERFICIAL MUSCLES

12. DIAGRAMMATIC VIEW OF POSTERIOR MUSCLES

13. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles of the Head: Facial Expression • Muscles of the scalp include the epicranius consisting of the frontalis and the occipitalis • Muscles of the face include corrugator supercilii, orbicularis oculi, zygomaticus, risorius, levator labii superioris, depressor labii inferioris, depressor anguli oris, orbicularis oris, mentalis, buccinator, and platysma

14. HEAD MUSCLES

15. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles of the Head: Mastication and Tongue Movement • Muscles of mastication include the masseter, temporalis, medial pterygoid, lateral pterygoid, and the buccinator • Muscles promoting tongue movement are the genioglossus, hypoglossus, and the styloglossus

16. TONGUE MUSCLES

17. TONGUE MUSCLES

18. TONGUE MUSCLES

19. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles of the Anterior Neck and Throat: Swallowing • Suprahyoid muscles include digastric, stylohyoid, mylohyoid, and geniohyoid • Infrahyoid muscles include sternohyoid, sternothyroid, omohyoid, thyrohyoid, and the pharyngeal constrictor muscles (superior, middle, and inferior)

20. NECK MUSCLES

21. NECK MUSCLES

22. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles of the Neck and Vertebral Column: Head and Trunk Movement • Anterolateral neck muscles include the sternocleidomastoid, and scalenes (anterior, middle, and posterior) • Intrinsic muscles of the back include splenius capitis, erector spinae or sacrospinalis, iliocostals, longissimus, spinalis, semispinalis, and the quadratus lumborum

23. NECK AND VERTEBRAL COLUMN MUSCLES

24. NECK AND VERTEBRAL COLUMN MUSCLES

25. NECK AND VERTEBRAL COLUMN MUSCLES

26. NECK AND VERTEBRAL COLUMN MUSCLES

27. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles of the Thorax: Breathing • Muscles of the thorax include the external intercostals, internal intercostals, and the diaphragm • Muscles of the Abdominal Wall: Trunk Movement and Compression of Abdominal Viscera • Muscles of the anterolateral abdominal wall include the rectus abdominis, external oblique, and the transversus abdominis

28. RESPIRATORY MUSCLES

29. RESPIRATORY MUSCLES

30. ABDOMINAL MUSCLES

31. ABDOMINAL MUSCLES

32. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles of the Pelvic Floor and Perineum: Support of Abdominopelvic Organs • Muscles of the pelvic diaphragm include the levator ani and the coccygeus • Muscles of the urogenital diaphragm include the deep transverse perineus and the sphincter urethrae • Muscles of the superficial space include the ischiocavernosus, bulbospongiosus, and the superficial transverse perineus

33. PELVIC FLOOR AND PERINEUM MUSCLES

34. PELVIC FLOOR AND PERINEUM MUSCLES

35. MAJOR SKELETAL MUSCLES OF THE BODY • Superficial Muscles of the Anterior and Posterior Thorax: Movements of the Scapula • Muscles of the anterior thorax include the pectoralis minor, serratus anterior, and the subclavius • Muscles of the posterior thorax include the trapezius, levator scapulae, and the rhomboids (major and minor)

36. THORAX MUSCLES

37. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles Crossing the Shoulder Joint: Movement of the Arm • Muscles moving the arm include the pectoralis major, latissimus dorsi, deltoid, subscapularis, supraspinatous, infraspinatous, teres minor, teres major, and the coracobrachialis

38. SHOULDER MUSCLES

39. SHOULDER MUSCLES

40. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles crossing the Elbow Joint: Flexion and Extension of the Forearm • Posterior muscles include the triceps brachii, and the anconeus • Anterior muscles include the biceps brachii, brachialis, and the brachioradialis

41. ANTERIOR ARM MUSCLES

42. POSTERIOR ARM MUSCLES

43. ARM MUSCLES

44. MAJOR SKELETAL MUSCLES OF THE BODY • Muscles of the Forearm: Movements of the Wrist, Hand, and Fingers • Anterior superficial muscles include the pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and the flexor digitorum superficialis • Anterior deep muscles include the flexor pollicis longus, flexor digitorum profundus, and the pronator quadratus • Posterior superficial muscles include the brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, and the extensor carpi ulnaris • Posterior deep muscles include the supinator, abductor pollicis longus, extensor pollicis longus, and the extensor pollicis brevis

45. MAJOR SKELETAL MUSCLES OF THE BODY • Summary of Actions of Muscles Acting on the Arm, Forehead, and Hand

46. ARM MUSCLE ACTIONS

47. ARM MUSCLE ACTIONS

48. MAJOR SKELETAL MUSCLES OF THE BODY • Intrinsic muscles of the Hand: Fine Movements of the Fingers • Thenar muscles in ball of thumb include the abductor pollicis brevis, flexor pollicis brevis, opponnens pollicis, and the adductor pollicis • Hypothenar muscles in ball of little finger include the abductor digiti minimi, flexor digiti minimi brevis, and the opponens digiti minimi • Midpalmar muscles include the lumbricals, palmar interossei, and the dorsal interossei

49. HAND MUSCLES

50. HAND MUSCLES