1. 1 Chapter 10 Lecture Outline Copyright © McGraw-Hill Education. Permission required for reproduction or display. See separate PowerPoint slides for all figures and tables pre- inserted into PowerPoint without notes.

2. Introduction Muscles constitute nearly half of the body’s weight and are of central interest in several fields of health care and fitness 10-2 Figure 10.5a Copyright © The McGraw-Hill Education. Permission required for reproduction or display.

3. The Structural and Functional Organization of Muscles Expected Learning Outcomes –Describe the varied functions of muscles. –Describe the connective tissue components of a muscle and their relationship to the bundling of muscle fibers. –Describe the various shapes of skeletal muscles and relate this to their functions. –Explain what is meant by the origin, insertion, belly, action, and innervation of a muscle. 10-3

4. The Structural and Functional Organization of Muscles (Continued) –Describe the ways that muscles work in groups to aid, oppose, or moderate each other’s actions. –Distinguish between intrinsic and extrinsic muscles. –Describe, in general terms, the nerve supply to the muscles and where these nerves originate. –Explain how the Latin names of muscles can aid in visualizing and remembering them. 10-4

5. The Structural and Functional Organization of Muscles About 600 human skeletal muscles Constitute about half of our body weight Three kinds of muscle tissue –Skeletal, cardiac, smooth Specialized for one major purpose –Converting the chemical energy in ATP into the mechanical energy of motion Myology—the study of the muscular system 10-5

6. The Functions of Muscles Muscle functions include: movement, stability, control of openings, heat production, and glycemic control Movement –Move from place to place; move body parts; move body contents in breathing, circulation, and digestion –In communication: speech, writing, facial expressions and other nonverbal communications Stability –Maintain posture by preventing unwanted movements –Antigravity muscles: prevent us from falling over –Stabilize joints by maintaining tension 10-6

7. The Functions of Muscles Control of openings and passageways –Sphincters: internal muscular rings that control the movement of food, blood, and other materials within body Heat production by skeletal muscles –As much as 85% of our body heat Glycemic control –Muscles absorb and store glucose which helps regulate blood sugar concentration within normal range 10-7

8. Connective Tissues of a Muscle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Skeletal muscle Perimysium Endomysium (a) Muscle fascicle Perimysium Epimysium Nerve Blood vessels Muscle fiber Tendon Fascia Muscle fiber Muscle fascicle 10-8 Figure 10.1a

9. Connective Tissues and Fascicles Endomysium –Thin sleeve of loose connective tissue around each fiber –Allows room for capillaries and nerve fibers –Provides chemical environment for muscle fiber Perimysium –Thicker layer of connective tissue that wraps fascicles Fascicles: bundles of muscle fibers wrapped together –Carries nerves, blood vessels, and stretch receptors Epimysium –Fibrous sheath surrounding entire muscle –Outer surface grades into fascia; inner surface projections form perimysium Fascia –Sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue 10-9

10. Connective Tissues and Fascicles Figure 10.1c 10-10

11. Fascicles and Muscle Shapes Figure 10.2 Strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles Fusiform Parallel Triangular Unipennate Bipennate Multipennate Circular Biceps brachii Rectus abdominis Pectoralis major Palmar interosseous Rectus femoris Deltoid Orbicularis oculi Tendon Belly Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-11

12. Fascicles and Muscle Shapes Fusiform muscles—thick in the middle and tapered at each end Parallel muscles—uniform width and parallel fascicles Triangular (convergent) muscles—broad at one end and narrow at the other Pennate muscles—feather shaped - Unipennate—fasciles approach tendon from one side - Bipennate—fascicles approach tendon from both sides - Multipennate—bunches of feathers converge to single point Circular muscles (sphincters)—form rings around body openings 10-12

13. Muscle Compartments Muscle compartment—a group of functionally related muscles enclosed by fascia –Also contains nerves and blood vessels that supply the muscle group Intermuscular septa are very thick fascia that separate one compartment from another 10-13 Figure 10.3 Anterior LateralMedial Posterior Key Posterior compartment, superficial layer Posterior compartment, deep layer Lateral compartment Anterior compartment Subcutaneous fat Fasciae Intermuscular septa Artery, veins, and nerve Interosseous membrane Fibula Tibia Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

14. Muscle Attachments Indirect attachment to bone –Tendons connect muscle to bone Collagen fibers of the endo-, peri-, and epimysium continue into the tendon and from there into periosteum and matrix of bone Aponeurosis—tendon is a broad, flat sheet (palmar aponeurosis) Retinaculum—connective tissue band that tendons from separate muscles pass under Direct (fleshy) attachment to bone –Little separation between muscle and bone –Muscle seems to emerge directly from bone 10-14

15. Muscle Origins and Insertions Origin –Bony attachment at stationary end of muscle Belly –Thicker, middle region of muscle between origin and insertion Insertion –Bony attachment to mobile end of muscle Figure 10.4 Scapula Bellies Radius Insertion Humerus Ulna Insertion Origins Long head Extensors: Lateral head Flexors: Biceps brachii Brachialis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Triceps brachii 10-15

16. Muscle Origins and Insertions Some anatomists prefer nontraditional descriptions of attachments by proximal vs. distal or superior vs. inferior Some muscles insert not on bone but on the fascia or tendon of another muscle or on collagen fibers of the dermis –Example: many facial muscles insert in the skin 10-16

17. Functional Groups of Muscles Action—effect produced by a muscle to produce or prevent movement Four categories of muscle action: prime mover, synergist, antagonist, and fixator –Prime mover (agonist) Muscle that produces most of force during a particular joint action –Synergist: muscle that aids the prime mover May contribute additional force, modify the direction of movement, or stabilize a nearby joint 10-17

18. Functional Groups of Muscles (Continued) –Antagonist: opposes the prime mover Prevents excessive movement Sometimes relaxes to give prime mover control over an action Antagonistic pairs—muscles that act on opposite sides of a joint –Fixator: muscle that prevents movement of bone 10-18

19. Functional Groups of Muscles For elbow flexion: Prime mover—brachialis Synergist—biceps brachii Antagonist—triceps brachii Fixator—muscle that holds scapula firmly in place – Rhomboids Figure 10.4 Scapula Bellies Radius Insertion Humerus Ulna Insertion Origins Extensors: Lateral head Flexors: Biceps brachii Brachialis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Long head Triceps brachii 10-19

20. Intrinsic and Extrinsic Muscles Intrinsic muscle— entirely contained within a region, such as the hand –Both origin and insertion there Extrinsic muscle—acts on a designated region, but has its origin elsewhere –Fingers: extrinsic muscles in the forearm Figure 10.28b Figure 10.31a (b) Intermediate flexor Flexor digitorum superficialis Flexor pollicis longus Flexor digitorum superficialis tendons Flexor digitorum profundus tendons Common flexor tendon Opponens pollicis Abductor pollicis brevis Flexor pollicis brevis Adductor pollicis Tendon of flexor digitorum superficialis Tendon of flexor digitorum profundus Abductor pollicis longus Palmaris longus Flexor digitorum superficialis Flexor carpi ulnaris Flexor retinaculum Abductor digiti minimi Flexor digiti Lumbricals Opponens digiti minimi Tendon sheath Flexor pollicis longus Flexor carpi radialis Tendon of flexor pollicis longus First dorsal interosseous Tendons of: Tendons of: (a) Palmar aspect, superficial Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-20

21. Muscle Innervation Innervation of a muscle—refers to the identity of the nerve that stimulates it –Knowing innervation enables diagnosis of nerve, spinal cord, and brainstem injuries from muscle tests Spinal nerves arise from the spinal cord –Emerge through intervertebral foramina –Immediately branch into posterior and anterior rami –Innervate muscles below the neck –Plexus: web-like network of spinal nerves adjacent to the vertebral column 10-21

22. Muscle Innervation Cranial nerves arise from the base of the brain –Emerge through skull foramina –Innervate the muscles of the head and neck –Numbered CN I to CN XII 10-22

23. Blood Supply Muscular system receives about 1.24 L of blood per minute at rest (one-quarter of the blood pumped by the heart) During heavy exercise, total cardiac output rises and the muscular system’s share is more than three-quarters (11.6 L/min) Capillaries branch extensively through the endomysium to reach every muscle fiber 10-23

24. How Muscles Are Named Latin names –Depressor labii inferioris, flexor digiti minimi brevis Describes distinctive aspects of the structure, location, or action of a muscle Footnotes throughout chapters show interpreted names of muscles Pronunciation of muscles available online at www.aprevealed.com 10-24

25. The Muscular System Figure 10.5b Figure 10.5a Frontalis Orbicularis oculi Masseter Orbicularis oris Trapezius External abdominal oblique Pronator quadratus Gastrocnemius Soleus Adductor longus Rectus abdominis Serratus anterior Sternocleidomastoid Deltoid Pectoralis major Biceps brachii Brachioradialis Sartorius Tensor fasciae latae Rectus femoris Fibularis longus Extensor digitorum longus Tibialis anterior Zygomaticus major Vastus lateralis Gracilis Vastus intermedius Adductors Extensor digitorum longus Supinator Flexor digitorum profundus Flexor pollicis longus Transverse abdominal Brachialis Coracobrachialis Platysma Flexor carpi radialis (a) Anterior view Vastus medialis Pectoralis minor Internal abdominal oblique DeepSuperficial Vastus lateralis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-25

26. A Learning Strategy Examine models, cadavers, dissected animals, or a photographic atlas Palpate muscles on yourself if possible Locate origins and insertions of muscles on an articulated skeleton Study derivation of each muscle name –Usually describes the muscle’s location, appearance, origin, insertion, or action Say the names aloud to yourself or study partner, and spell them correctly 10-26

27. Muscles of the Head and Neck Expected Learning Outcomes –Name and locate the muscles that produce facial expression. –Name and locate the muscles used for chewing and swallowing. –Name and locate the neck muscles that move the head. –Identify the origin, insertion, action, and innervation of any of these muscles. 10-27

28. Muscles of Facial Expression Muscles that insert in the dermis and subcutaneous tissues Tense the skin and produce facial expressions Innervated by facial nerve (CN VII) Paralysis causes face to sag Found in scalp, forehead, around the eyes, nose, and mouth, and in the neck 10-28

29. Muscles of Facial Expression Figure 10.8a Frontalis Galea aponeurotica Orbicularis oculi Platysma (a) Anterior view Mentalis (cut) Orbicularis oris Masseter Zygomaticus minor Levator labii superioris Zygomaticus major Risorius Depressor anguli oris Depressor labii inferioris Nasalis Corrugator supercilii Buccinator Modiolus Levator anguli oris Superficial Deep Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-29

30. Muscles of Facial Expression Frontalis (cut)Galea aponeurotica Orbicularis oculi Sternohyoid Orbicularis oris Occipitalis Omohyoid Sternothyroid Inferior pharyngeal constrictor Sternocleidomastoid Masseter Thyrohyoid Zygomatic arch Levator labii superioris Zygomaticus minor Zygomaticus major Depressor labii inferioris Depressor anguli oris Buccinator Risorius (cut) Nasalis Corrugator supercilii Mentalis Levator scapulae (b) Lateral view Modiolus Temporalis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 10.8b 10-30

31. Muscles of Chewing and Swallowing Extrinsic muscles of the tongue –Tongue is very agile organ –Pushes food between molars for chewing (mastication) –Forces food into the pharynx for swallowing (deglutition) –Crucial importance to speech Intrinsic muscles of tongue –Vertical, transverse, and longitudinal fascicles Figure 10.9 Genioglossus Styloglossus Palatoglossus Posterior belly of digastric (cut) Stylohyoid Superior pharyngeal constrictor (cut) Middle pharyngeal constrictor Inferior pharyngeal constrictor Hyoglossus Hyoid bone Styloid process Mastoid process Mylohyoid (cut) Geniohyoid Esophagus Inferior longitudinal muscle of tongue Larynx Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Trachea 10-31

32. Muscles of Chewing and Swallowing Four pairs of muscles produce biting and chewing movements of the mandible –Depression: to open mouth –Elevation: biting and grinding –Protraction: incisors can cut –Retraction: make rear teeth meet –Lateral and medial excursion: grind food Temporalis, masseter, medial pterygoid, and lateral pterygoid Innervated by mandibular nerve, a branch of the trigeminal (CN V) Figure 10.10a,b Temporalis Orbicularis oris Masseter (cut) (a) Lateral view Buccinator Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (b) Posterior view Medial pterygoid muscle Medial pterygoid plate Lateral pterygoid plate Interior of oral cavity Lateral pterygoid muscle 10-32

33. Muscles of Chewing and Swallowing Hyoid muscles—suprahyoid group Aspects of chewing, swallowing, and vocalizing Eight pairs of hyoid muscles associated with hyoid bone Digastric—opens mouth widely Geniohyoid—depresses mandible Mylohyoid—elevates floor of mouth at beginning of swallowing Stylohyoid—elevates hyoid Figure 10.11a Levator scapulae Sternocleidomastoid Digastric: Anterior belly Posterior belly Stylohyoid Mylohyoid Sternohyoid Omohyoid: Suprahyoid group Infrahyoid group (a) Anterior view Hyoid bone Common carotid artery Internal jugular vein Clavicle Thyrohyoid Superior belly Inferior belly SuperficialDeep Infrahyoid group Sternothyroid Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-33

34. Muscles of Chewing and Swallowing Hyoid muscles—infrahyoid group Fix hyoid bone from below, allowing suprahyoid muscles to open mouth Omohyoid—depresses hyoid after elevation Sternohyoid—depresses hyoid after elevation Thyrohyoid—depresses hyoid and elevates larynx Sternothyroid—depresses larynx after elevation Figure 10.11b 10-34 Stylohyoid Hyoglossus Mylohyoid Digastric (anterior belly) Hyoid bone Thyrohyoid Omohyoid (superior belly) Sternothyroid Sternohyoid (b) Lateral view Digastric (posterior belly) Splenius capitis Inferior pharyngeal constrictor Sternocleidomastoid Trapezius Levator scapulae Scalenes Omohyoid (inferior belly) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

35. Muscles of Chewing and Swallowing Pharynx: three pairs pharyngeal constrictors –Encircle pharynx forming a muscular funnel –During swallowing, drive food into the esophagus Figure 10.9 Genioglossus Styloglossus Palatoglossus Posterior belly of digastric (cut) Stylohyoid Superior pharyngeal constrictor (cut) Middle pharyngeal constrictor Inferior pharyngeal constrictor Hyoglossus Hyoid bone Styloid process Mastoid process Mylohyoid (cut) Geniohyoid Esophagus Inferior longitudinal muscle of tongue Larynx Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Trachea 10-35

36. Muscles Acting on the Head Originate on vertebral column, thoracic cage, and pectoral girdle Insert on the cranial bones Actions –Flexion (tipping head forward) –Extension (holding the head erect) –Lateral flexion (tipping head to one side) –Rotation (turning the head to the left and right) 10-36

37. Muscles Acting on the Head Neck flexors –Sternocleidomastoid –Scalenes Neck extensors –Trapezius –Splenius capitis –Semispinalis capitis 10-37 Figure 10.12

38. Muscles Acting on the Head May cause contralateral movement: movement of the head toward the opposite side May cause ipsilateral movement: movement of the head toward the same side 10-38

39. Muscles of the Trunk Expected Learning Outcomes –Name and locate the muscles of respiration and explain how they affect airflow and abdominal pressure. –Name and locate the muscles of the abdominal wall, back, and pelvic floor. –Identify the origin, insertion, action, and innervation of any of these muscles. 10-39

40. Muscles of the Trunk Three functional groups –Muscles of respiration –Muscles that support abdominal wall and pelvic floor –Movement of vertebral column 10-40

41. Muscles of Respiration Breathing requires the use of muscles enclosing thoracic cavity –Diaphragm, external intercostal, internal intercostal, and innermost intercostal muscles Inspiration—air intake Expiration—expelling air 10-41

42. Muscles of Respiration Other muscles of chest and abdomen that contribute to breathing –Sternocleidomastoid, scalenes of neck –Pectoralis major and serratus anterior of chest –Latissimus dorsi of back –Abdominal muscles: internal and external obliques, and transverse abdominis –Even some anal muscles 10-42

43. Muscles of Respiration Figure 10.13b Xiphoid process of sternum Esophagus Aorta Inferior vena cava Central tendon of diaphragm (b) Inferior view of diaphragm Vertebral column Ribs Diaphragm—muscular dome between thoracic and abdominal cavities Muscle fascicles extend to a fibrous central tendon Contraction flattens diaphragm –Enlarges thoracic cavity (inspiration) In relaxation of diaphragm it rises –Shrinks the thoracic cavity (expiration) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-43

44. Muscles of Respiration External intercostals –Elevate ribs –Expand thoracic cavity –Create partial vacuum causing inflow of air Internal intercostals –Depresses and retracts ribs –Compresses thoracic cavity –Expelling air Innermost intercostals –Same action as internal intercostals Figure 10.13a External intercostals Internal intercostals (a) Lateral view of intercostal muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-44

45. Muscles of the Anterior Abdominal Wall Internal abdominal oblique –Intermediate layer of lateral abdominal muscles –Unilateral contraction causes ipsilateral rotation of waist –Aponeurosis Tendons of oblique and transverse muscles Broad, fibrous sheets Subclavius Pectoralis minor (cut) Internal intercostals External intercostals Rectus abdominis (cut) External abdominal oblique (cut) Internal abdominal oblique (cut) Transverse abdominal (cut) Posterior wall of rectus sheath (rectus abdominis removed) Internal abdominal oblique Inguinal ligament Rectus sheath Serratus anterior Pectoralis minor (b) Deep Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 10.15b 10-45

46. Muscles of the Anterior Abdominal Wall Transverse abdominal –Deepest of lateral abdominal muscles –Horizontal fibers –Compresses abdominal contents –Contributes to movements of vertebral column Subclavius Pectoralis minor (cut) Internal intercostals External intercostals Rectus abdominis (cut) External abdominal oblique (cut) Internal abdominal oblique (cut) Transverse abdominal (cut) Posterior wall of rectus sheath (rectus abdominis removed) Internal abdominal oblique Inguinal ligament Rectus sheath Serratus anterior Pectoralis minor (b) Deep Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 10.15b 10-46

47. Muscles of the Anterior Abdominal Wall Rectus abdominis –Flexes lumbar region of vertebral column –Produces forward bending at the waist –Extends from sternum to pubis –Rectus sheath encloses muscle –Three transverse tendinous intersections divide rectus abdominis into segments, sometimes called a “six pack” Figure 10.15a Pectoralis major Tendinous intersections Linea alba Latissimus dorsi Rectus abdominis Inguinal ligament Rectus sheath (cut edges) Serratus anterior Aponeurosis of external abdominal oblique Umbilicus Linea semilunaris Transverse abdominal Internal abdominal oblique (cut) External abdominal oblique (cut) Rectus sheath (a) Superficial Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-47

48. Muscles of Back Back muscles extend, rotate, and laterally flex vertebral column Most prominent superficial back muscles: latissimus dorsi and trapezius Upper limb movement Figure 10.17 10-48

49. Muscles of the Back Deep muscles Erector spinae –Iliocostalis, longissimus, spinalis –From cranium to sacrum –Extension and lateral flexion of vertebral column Semispinalis thoracis –Extension and contralateral rotation of vertebral column Figure 10.18 Longissimus capitis Semispinalis capitis Internal abdominal oblique Erector spinae: Semispinalis thoracis Multifidus Quadratus lumborum Superior nuchal line Splenius capitis Serratus posterior superior Splenius cervicis External abdominal oblique (cut) Semispinalis cervicis Serratus posterior inferior Iliocostalis Longissimus Spinalis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-49

50. Muscles of the Back (Continued) Quadratus lumborum –Aids respiration –Ipsilateral flexion of lumbar vertebral column Multifidus –Stabilizes adjacent vertebrae –Maintains posture 10-50

51. Muscles of the Pelvic Floor Layers of muscles and fasciae that span pelvic outlet –Penetrated by anal canal, urethra, and vagina Perineum—diamond-shaped region between the thighs –Bordered by four bony landmarks Pubic symphysis anteriorly Coccyx posteriorly Ischial tuberosities laterally –Urogenital triangle: anterior half of perineum –Anal triangle: posterior half of perineum 10-51

52. Muscles of the Pelvic Floor Layers or compartments of the perineum –Superficial perineal space Ischiocavernosus, bulbospongiosus –Deep perineal space Deep transverse perineal, compressor urethrae –Anal triangle External anal sphincter –Pelvic diaphragm: deepest (most superior) layer Levator ani 10-52

53. Muscles of the Pelvic Floor Superficial perineal space – Ischiocavernosus—maintains erection – Bulbospongiosus—aids in erection, expels remaining urine Figure 10.20a 10-53

54. Muscles of the Pelvic Floor Deep perineal space – Urogenital triangle—contains deep transverse perineal muscle and compressor urethrae in females Anal triangle—external anal sphincter Figure 10.20b 10-54

55. Muscles of the Pelvic Floor Pelvic diaphragm: deepest compartment of the perineum – Levator ani: supports viscera and defecation – Coccygeus muscle(s) Figure 10.20c 10-55

56. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Aponeurosis of external abdominal oblique muscle Inguinal canal External inguinal ring Herniated loop of small intestine Upper scrotum Hernias Hernia—any condition in which the viscera protrudes through a weak point in the muscular wall of the abdominopelvic cavity Inguinal hernia –Most common type of hernia (rare in women) –Viscera enter inguinal canal or even the scrotum Hiatal hernia –Stomach protrudes through diaphragm into thorax –Overweight people over 40 Umbilical hernia –Viscera protrude through the navel 10-56 Figure 10.21

57. Muscles Acting on the Shoulder and Upper Limb Expected Learning Outcomes –Name and locate the muscles that act on the pectoral girdle, shoulder, elbow, wrist, and hand. –Relate the actions of these muscles to the joint movements described in chapter 9. –Describe the origin, insertion, and innervation of each muscle. 10-57

58. Muscles Acting on the Shoulder and Upper Limb Compartments—spaces where muscles are separated by fibrous connective tissue sheets (fasciae) –Each compartment contains one or more functionally related muscles along with their nerve and blood supplies Muscles of upper limbs divided into anterior and posterior compartments Intermuscular septa (thick fascia) separates compartments Compartment syndrome—one of the muscles or blood vessels in a compartment is injured 10-58

59. Compartment Syndrome If a blood vessel in a compartment is damaged, blood and tissue fluid accumulate Fasciae enclose muscle compartments snugly and prevent expansion Compartment syndrome—mounting pressure triggers a sequence of degenerative events –Blood flow to compartment is obstructed by pressure –If ischemia (poor blood flow) persists for more than 2 to 4 hours, nerves begin to die –After 6 hours, muscles begin to die Nerves can regenerate after pressure relieved, but muscle damage is permanent Myoglobin in urine indicates compartment syndrome Treatment: immobilization of limb and fasciotomy (incision to relieve compartment pressure) 10-59

60. Muscles Acting on the Shoulder and Upper Limb Upper limb is used for a broad range of powerful and subtle actions –Climbing, grasping, throwing, writing, playing musical instruments, and manipulating small objects Muscles that act on the scapula Muscles that act on the humerus and shoulder joint Muscles that act on the forearm and elbow joint Muscles that act on the wrist, hand, and fingers 10-60

61. Muscles Acting on the Shoulder A group of muscles originate on the axial skeleton and insert on clavicle or scapula Scapula loosely attached to thoracic cage –Capable of great movement –Rotation, elevation, depression, protraction, retraction Clavicle braces the shoulder and moderates movements 10-61

62. Muscles Acting on the Scapula Figure 10.22 10-62

63. Muscles Acting on the Shoulder Pectoralis minor –Ribs 3–5 to coracoid process of scapula –Draws scapula laterally Serratus anterior – All ribs to medial border of scapula – Draws scapula laterally and forward; prime mover for reaching and pushing Subclavius Pectoralis minor (cut) Internal intercostals External intercostals Rectus abdominis (cut) Inguinal ligament Rectus sheath Serratus anterior Pectoralis minor (b) Deep Internal abdominal oblique Transverse abdominal (cut) Posterior wall of rectus sheath (rectus abdominis removed) Internal abdominal oblique (cut) External abdominal oblique (cut) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 10.15b 10-63 Anterior group of muscles of pectoral girdle

64. Muscles Acting on the Shoulder Four muscles of posterior group –Trapezius: superficial –Levator scapulae, Rhomboid minor, and Rhomboid major: deep Trapezius –Stabilizes scapula and shoulder –Elevates and depresses shoulder apex Figure 10.17 Semispinalis capitis Sternocleidomastoid Deltoid Levator scapulae Rhomboid minor Rhomboid major Infraspinatus Gluteus maximus Gluteus medius Gluteus minimus Lateral rotators Serratus anterior Supraspinatus Erector spinae Splenius capitis SuperficialDeep Trapezius Latissimus dorsi External abdominal oblique Thoracolumbar fascia Teres minor Teres major Serratus posterior inferior External abdominal oblique Internal abdominal oblique Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-64 Posterior group of muscles of pectoral girdle

65. Muscles Acting on the Shoulder (Continued from slide 170) Levator scapulae –Elevates scapula –Flexes neck laterally Rhomboid minor –Retracts scapula and braces shoulder Rhomboid major –Same as Rhomboid minor 10-65

66. Muscles Acting on the Shoulder Figure 10.17 Semispinalis capitis Sternocleidomastoid Deltoid Levator scapulae Rhomboid minor Rhomboid major Infraspinatus Gluteus maximus Gluteus medius Gluteus minimus Lateral rotators Serratus anterior Supraspinatus Erector spinae Splenius capitis SuperficialDeep Trapezius Latissimus dorsi External abdominal oblique Thoracolumbar fascia Teres minor Teres major Serratus posterior inferior External abdominal oblique Internal abdominal oblique Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-66 Posterior scapular muscles

67. Muscles Acting on the Arm Nine muscles cross the shoulder joint and insert on humerus Two are axial muscles originating on axial skeleton –Pectoralis major: flexes, adducts, and medially rotates humerus –Latissimus dorsi: adducts and medially rotates humerus Figure 10.23a Figure 10.23b Clavicle Deltoid Sternum Pectoralis major Coracobrachialis Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis Triceps brachii: (a) Anterior view Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (b) Posterior view Supraspinatus Spine of scapula Infraspinatus Lateral head Long head Latissimus dorsi Humerus Greater tubercle of humerus Teres minor Teres major Triceps brachii: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-67

68. Anterior View of Cadaver Chest Figure 10.24a 10-68

69. Back Muscles of Cadaver Figure 10.24b 10-69

70. Seven muscles with scapular origin –Deltoid Rotates and abducts arm Intramuscular injection site – Teres major Extension and medial rotation of humerus –Coracobrachialis Flexes and medially rotates arm –Remaining four form the rotator cuff that reinforce the shoulder joint Muscles Acting on the Arm Figure 10.23b Figure 10.23a Clavicle Deltoid Sternum Pectoralis major Coracobrachialis Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis Triceps brachii: (a) Anterior view Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (b) Posterior view Supraspinatus Spine of scapula Infraspinatus Lateral head Long head Latissimus dorsi Humerus Greater tubercle of humerus Teres minor Teres major Triceps brachii: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-70

71. Muscles Acting on the Arm Rotator cuff muscles Tendons of the remaining four scapular muscles form the rotator cuff Acronym “SITS muscles” –Supraspinatus –Infraspinatus –Teres minor –Subscapularis Tendons of these muscles merge with the joint capsule of the shoulder as they cross it in route to the humerus Holds head of humerus into glenoid cavity Supraspinatus tendon easily damaged 10-71

72. Rotator Cuff Muscles Figure 10.25 Acromion Inferior angle Clavicle Infraspinatus Subscapularis Glenoid cavity Supraspinatus Anterior Posterior Rotator cuff (SITS) muscles: Teres minor Coracoid process Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10-72

73. Muscles Acting on the Forearm Elbow and forearm capable of flexion, extension, pronation, and supination –Carried out by muscles in both brachium (arm) and antebrachium (forearm) Muscles with bellies in the arm (brachium) –Principal elbow flexors: anterior compartment Brachialis and biceps brachii –Brachialis produces 50% more power than biceps brachii –Brachialis is prime mover of elbow flexion –Principal elbow extensor: posterior compartment Triceps brachii –Prime mover of elbow extension 10-73

74. Muscles Acting on the Forearm Principal flexor –Brachialis Synergistic flexors –Biceps brachii –Brachioradialis Principal extensor –Triceps brachii Figure 10.23b Figure 10.23a Clavicle Deltoid Sternum Pectoralis major Coracobrachialis Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis Triceps brachii: (a) Anterior view Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (b) Posterior view Supraspinatus Spine of scapula Infraspinatus Lateral head Long head Latissimus dorsi Humerus Greater tubercle of humerus Teres minor Teres major Triceps brachii: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Biceps brachii: Long head Short head (c) Anterior view Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 10.23c 10-74

75. Muscles Acting on the Forearm Muscles with bellies in the forearm (antebrachium) –Brachioradialis: flexes elbow –Anconeus: extends elbow –Pronator quadratus: prime mover in forearm pronation –Pronator teres: assists pronator quadratus in pronation –Supinator: supinates the forearm 10-75

76. Muscles Acting on the Forearm Supination –Supinator muscle –Palm facing anteriorly or superiorly Pronation – Pronator quadratus and pronator teres – Palm faces posteriorly or inferiorly Figure 10.26aFigure 10.26c Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Medial epicondyle Lateral epicondyle Ulna Pronator quadratus Pronator teres Supinator Radius (a) Supination Ulna Bursa Biceps brachii Supinator (b) Muscle actions in supination Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Medial epicondyle Lateral epicondyle Ulna Pronator quadratus Pronator teres Supinator Radius (c) Pronation Ulna Bursa Biceps brachii Supinator (b) Muscle actions in supination 10-76

77. Muscles Acting on the Wrist and Hand Anterior group Extrinsic muscles of the forearm Intrinsic muscles in the hand itself Extrinsic muscle actions –Flexion and extension of wrist and digits –Radial and ulnar flexion –Finger abduction and adduction –Thumb opposition Figure 10.28a,b,c Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (c) Deep flexors(b) Intermediate flexor (a) Superficial flexors Flexor digitorum superficialis Flexor digitorum profundus Supinator Flexor pollicis longus Biceps brachii Brachialis Pronator teres Brachioradialis Flexor carpi radialis Palmaris longus Flexor digitorum superficialis Extensor carpi radialis longus and brevis Triceps brachii Common flexor tendon Aponeurosis of biceps brachii Flexor carpi ulnaris Interosseous membrane Flexor pollicis longus Flexor digitorum superficialis tendons Flexor digitorum profundus tendons Common flexor tendon Palmar aponeurosis Flexor digitorum superficialis tendons Flexor digitorum profundus tendons Flexor retinaculum Anterior view 10-77

78. Anterior (flexor) compartment—superficial layer –Flexor carpi radialis –Flexor carpi ulnaris –Flexor digitorum superficialis –Palmaris longus Anterior (flexor) compartment—deep layer –Flexor digitorum profundus –Flexor pollicis longus Muscles Acting on the Wrist and Hand 10-78

79. Cross Section of Upper Limb Figure 10.27a,b,c Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Flexor carpi radialis Flexor carpi ulnaris Palmaris longus Flexor pollicis longus Flexor digitorum profundus Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris (c) Pronator teres Radius Ulna Anconeus Brachioradialis Flexor digitorum superficialis Supinator Short head Long head Pectoralis major Triceps brachii: Coracobrachialis Humerus Deltoid Teres major Latissimus dorsi tendon Biceps brachii: Lateral head Long head (a) Brachialis Biceps brachii Triceps brachii: Medial head Long head Lateral head (b) Anterior (flexor) compartment, superficial Anterior (flexor) compartment, deep Posterior (extensor) compartment Other muscles Key (a) (b) (c) Posterior Anterior LateralMedial 10-79

80. Muscles Acting on the Wrist and Hand Posterior group Extension of wrist and fingers, adduct/abduct wrist Extension and abduction of thumb (pollicis) Brevis means “short,” ulnaris indicates “on ulna side of forearm” Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anconeus Supinator Abductor pollicis longus Extensor pollicis longus Extensor pollicis brevis Extensor indicis Olecranon Tendons of extensor digitorum (a) Superficial extensors (b) Deep extensors Posterior view Extensor carpi ulnaris Anconeus Triceps brachii Flexor carpi ulnaris Extensor digiti minimi Tendon of extensor indicis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Brachioradialis Tendons of extensor carpi radialis longus and brevis Figure 10.29a,b 10-80

81. Muscles Acting on the Wrist and Hand Posterior (extensor) compartment—superficial layer –Extensor carpi radialis longus –Extensor carpi radialis brevis –Extensor digitorum –Extensor digiti minimi –Extensor carpi ulnaris Posterior (extensor) compartment—deep layer –Abductor pollicis longus –Extensor pollicis brevis –Extensor pollicis longus –Extensor indicis 10-81

82. Carpal Tunnel Syndrome Flexor retinaculum—bracelet-like fibrous sheet, passed under by flexor tendons crossing the wrist Carpal tunnel—tight space between the flexor retinaculum and the carpal bones –Flexor tendons passing through the tunnel are enclosed in tendon sheaths Enable tendons to slide back and forth quite easily 10-82

83. Carpal Tunnel Syndrome Carpal tunnel syndrome—prolonged, repetitive motions of wrist and fingers cause tissues in the carpal tunnel to become inflamed, swollen, or fibrotic –Puts pressure on median nerve of wrist that passes through the carpal tunnel along with flexor tendons –Tingling and muscular weakness in the palm and medial side of the hand –Pain may radiate to arm and shoulder –Treatment: anti-inflammatory drugs, immobilization of the wrist, and sometimes surgery to remove part or all of flexor retinaculum 10-83

84. Carpal Tunnel Syndrome Repetitive motions cause inflammation and pressure on median nerve Figure 10.31a Figure 10.31b Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Opponens pollicis Abductor pollicis brevis Flexor pollicis brevis Adductor pollicis Tendon of flexor digitorum superficialis Tendon of flexor digitorum profundus Palmaris longus Flexor digitorum superficialis Flexor retinaculum Abductor digiti minimi Flexor digiti minimi brevis Lumbricals Opponens digiti minimi Tendon sheath Flexor pollicis longus Flexor carpi radialis Tendon of flexor pollicis longus First dorsal interosseous Flexor carpi ulnaris Abductor pollicis longus (a) Palmar aspect, superficial Tendons of: 10-84

85. Intrinsic Muscles of the Hand Thenar group—form thick, fleshy mass at base of thumb –Adductor pollicis –Abductor pollicis brevis –Flexor pollicis brevis –Opponens pollicis Hypothenar group—fleshy base of the little finger –Abductor digiti minimi –Flexor digiti minimi brevis –Opponens digiti minimi Midpalmar group—hollow of palm –Dorsal interosseous muscles (4) –Palmar interosseous muscles (3) –Lumbricals (4 muscles) 10-85

86. Muscles Acting on the Hip and Lower Limb Expected Learning Outcomes –Name and locate the muscles that act on the hip, knee, ankle, and toe joints. –Relate the actions of these muscles to the joint movements described in chapter 9. –Describe the origin, insertion, and innervation of each muscle. 10-86

87. Muscles Acting on the Hip and Lower Limb Body’s largest muscles found in lower limb Less for precision, more for strength needed to stand, maintain balance, walk, and run Several cross and act on two or more joints Leg—the part of the limb between the knee and ankle Foot—includes tarsal region (ankle), metatarsal region, and the toes 10-87

88. Muscles Acting on the Hip and Femur Anterior muscles of the hip –Iliacus Flexes thigh at hip Iliacus portion arises from iliac crest and fossa –Psoas major Flexes thigh at hip Arises from lumbar vertebrae –They share a common tendon on the femur Figure 10.32 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Iliopsoas: Iliacus Psoas major Adductor longus Adductor brevis Pectineus Gracilis Insertion of gracilis on tibia Piriformis Obturator externus Adductor magnus 10-88

89. Muscles Acting on the Hip and Femur Lateral and posterior muscles of the hip –Tensor fasciae latae Extends knee, laterally rotates knee –Gluteus maximus Forms mass of the buttock Prime hip extensor Provides most of lift when you climb stairs –Gluteus medius and minimus Abduct and medially rotate thigh Figure 10.33 10-89

90. Muscles Acting on the Hip and Femur Posterior group Lateral rotators—six muscles inferior to gluteus minimus Deep to the two other gluteal muscles –Gemellus superior –Gemellus inferior –Obturator externus –Obturator internus –Piriformis –Quadratus femoris 10-90

91. Muscles Acting on the Hip and Femur Medial (adductor) compartment of thigh Five muscles act as primary adductors of the thigh –Adductor brevis –Adductor longus –Adductor magnus –Gracilis –Pectineus Figure 10.32 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Iliopsoas: Iliacus Psoas major Adductor longus Adductor brevis Pectineus Gracilis Insertion of gracilis on tibia Piriformis Obturator externus Adductor magnus 10-91

92. Muscles Acting on the Knee and Leg Anterior (extensor) compartment of the thigh – Contains large quadriceps femoris muscle Prime mover of knee extension Most powerful muscle in the body Has four heads—rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius – All converge on single quadriceps (patellar) tendon – Extends to patella – Then continues as patellar ligament – Inserts on tibial tuberosity – Sartorius: longest muscle in the body “Tailor’s muscle” 10-92

93. Anterior Thigh Cadaver Muscles Figure 10.34 10-93

94. Muscles Acting on the Knee and Leg Figure 10.35a,b 10-94

95. Muscles Acting on the Knee and Leg Posterior (flexor) compartment of the thigh – Contains hamstring muscles – From lateral to medial: Biceps femoris Semitendinosus Semimembranosus Figure 10.33 10-95

96. Muscles Acting on the Foot Crural muscles, acting on the foot, are separated into three compartments –Anterior compartment (red) –Fibular (lateral) compartment (green) –Posterior compartments (superficial = pink) (deep = purple) Figure 10.40b Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a) (b) Fibularis longus Fibularis brevis (b) Gastrocnemius (medial head) Gastrocnemius (lateral head) Fibula Extensor hallucis longus Extensor digitorum longus Soleus Flexor hallucis longus Tibialis posterior Tibia Tibialis anterior Flexor digitorum longus Anterior (extensor) compartment Lateral (fibular) compartment Posterior (flexor) compartment, superficial Posterior (flexor compartment, deep) Key b Anterior Posterior LateralMedial 10-96

97. Muscles Acting on the Foot Anterior (extensor) compartment of the leg – Dorsiflex the ankle – Prevent toes from scuffing ground when walking – Fibularis (peroneus) tertius – Extensor digitorum longus – Extensor hallucis longus – Tibialis anterior Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tibialis anterior Extensor digitorum brevis Extensor hallucis brevis Fibularis tertius Extensor digitorum longus Tibialis anterior Fibularis longus Extensor digitorum longus Fibularis brevis Patella Patellar ligament Gastrocnemius Soleus Tibia Extensor retinacula Extensor hallucis longus (a)(b)(c)(d) Figure 10.38a–d 10-97

98. Muscles Acting on the Foot Posterior compartment—three muscles of the superficial group – Gastrocnemius: plantar flexes foot, flexes knee – Soleus: plantar flexes foot – Plantaris: weak synergist of triceps surae Triceps surae—collective name for gastrocnemius and soleus – Inserts on calcaneus by way of the calcaneal (Achilles) tendon – Strongest tendon in the body Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Gastrocnemius: Heads of gastrocnemius (cut) Calcaneal tendon Calcaneus Medial head Lateral head Popliteus Flexor digitorum longus Plantaris Soleus Flexor hallucis longus Tendon of plantaris Fibularis brevis Fibularis longus Fibularis longus Gastrocnemius (cut) Tendon of gastrocnemius (a)(b) Figure 10.38a,b 10-98

99. Muscles Acting on the Foot Posterior compartment—four muscles in the deep group – Flexor digitorum longus: flexes phalanges – Flexor hallucis longus: flexes great toe – Tibialis posterior: inverts foot – Popliteus: acts on knee Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Calcaneal tendon (cut) Calcaneus(a) (b) (c) (d) Flexor digitorum longus Flexor digitorum longus Flexor hallucis longus Flexor hallucis longus Popliteus Plantaris (cut) Soleus (cut) Fibula Fibularis longus Fibularis brevis Gastrocne -mius (cut) Plantar surface of the foot Tibialis posterior Tibialis posterior Figure 10.39 10-99

100. Muscles Acting on the Foot Lateral (fibular) compartment—two muscles – Fibularis longus – Fibularis brevis Both plantar flex and evert the foot Provide lift and forward thrust Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Calcaneal tendon (cut) Calcaneus (a) Flexor digitorum longus Flexor hallucis longus Popliteus Plantaris (cut) Soleus (cut) Fibula Fibularis longus Fibularis brevis Gastrocnemius (cut) Tibialis posterior Figure 10.39a 10-100

101. Intrinsic Muscles of Foot One dorsal muscle –Extensor digitorum brevis extends toes Four ventral muscle layers –Support arches –Abduct and adduct the toes –Flex the toes Figure 10.41a–e Dorsal view (a) Layer 1, plantar view(b) Layer 2, plantar view Abductor hallucis Calcaneus Lumbricals Quadratus plantae (c) Layer 3, plantar view(d) Layer 4, plantar view(e) Layer 4, dorsal view Adductor hallucis Flexor hallucis brevis Abductor hallucis (cut) Flexor digiti minimi brevis Abductor digiti minimi Flexor digitorum brevis Plantar aponeurosis (cut) Flexor digitorum brevis (cut) Flexor hallucis longus tendon Flexor digitorum longus tendon Abductor hallucis (cut) Flexor hallucis longus tendon (cut) Flexor digitorum longus tendon (cut) Plantar interosseous Dorsal interosseous Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Flexor digiti minimi brevis Quadratus plantae (cut) 10-101

102. Common Athletic Injuries Muscles and tendons are vulnerable to sudden and intense stress Proper conditioning and warm-up needed Common injuries include: –Compartment syndrome –Shin splints –Pulled hamstrings –Tennis elbow –Pulled groin –Rotator cuff injury Treat with rest, ice, compression, and elevation “No pain, no gain” is a dangerous misconception 10-102