Chapter 11 Lecture Outline Part 1 of 2

Transcription

1 Chapter 11 Lecture Outline Part 1 of 2 See separate PowerPoint slides for all figures and tables preinserted into PowerPoint without notes. Copyright McGraw-Hill Education. Permission required for reproduction or display. 1

2 Axial muscles Introduction: Axial and Appendicular Muscles Have both origins and insertions on axial skeleton Support and move the head and vertebral column Function in facial expression, breathing, chewing and swallowing Support and protect abdominal and pelvic organs Appendicular muscles Control movements of upper and lower limbs Control movements of pectoral and pelvic girdles Organized into groups based on locations 2

3 Body Musculature: Anterior View Figure 11.1a 3

4 Body Musculature: Posterior View Figure 11.1b 4

5 11.1a Origin and Insertion Origin Less movable attachment of a muscle Typically the more proximal attachment Insertion More movable attachment of a muscle: pulled toward origin when muscle contracts Typically the more distal attachment 5

6 11.1a Origin and Insertion Origins of biceps brachii are on scapula Insertion of biceps brachii is on radius Contraction pulls forearm toward shoulder Figure

7 11.1b Organizational Patterns of Skeletal Muscle Fibers Varied organization of fascicles (bundles of muscle fibers) Circular muscles: concentrically arranged fascicles o Create a sphincter o Control material passage through an opening Parallel muscles: fascicles run parallel to muscle s long axis o Sometimes have an expanded central belly o High endurance Convergent muscles: fascicles merge toward a common attachment site o Common site might be a tendon, sheet, or raphe (seam) o Can pull in varying directions, but not as hard as parallel muscles of same size Pennate muscles: fascicles organized as if part of a large feather o Fibers pull at an angle to the tendon o Generate more tension but don t pull their tendons as far as parallel muscles of same size o Three subtypes: unipennate, bipennate, and multipennate 7

8 11.1b Organizational Patterns of Skeletal Muscle Fibers Figure 11.3 Unipennate: All fibers on same side of tendon Bipennate: Fibers on both sides of tendon Multipennate: Tendon branches within muscle 8

9 11.1c Actions of Skeletal Muscles Muscles grouped by primary actions Agonist o Prime mover; muscle that contracts to produce a movement o E.g., triceps brachii is agonist for forearm extension Antagonist o Muscle whose contraction opposes that of the agonist This allows for smooth movement of controlled speed o E.g., biceps brachii, is antagonist for forearm extension Synergist o Muscle that assists agonist by contributing tension or stabilizing point of origin (acting as fixators) o E.g., biceps brachii and brachialis muscle work synergistically to flex elbow joint 9

10 11.2 Skeletal Muscle Naming How are muscles named? Muscle action: indicates muscle s primary function o E.g., flexor digitorum longus flexes digits Specific body regions: indicates muscle location o E.g., rectus femoris is near the femur Muscle attachments: indicates origins and/or insertions o E.g., sternocleidomastoid originates on the sternum and clavicle and inserts on the mastoid process Orientation of muscle fibers: indicates organization of muscle fascicles o E.g., rectus abdominis is composed of fibers running in vertically straight ( rectus ) orientation 10

11 11.2 Skeletal Muscle Naming How are muscles named? (continued) Muscle shape o E.g., deltoid is shaped like a triangular delta symbol o E.g., abductor pollicis longus is a long muscle Muscle size o E.g., gluteus maximus is the largest of the buttocks muscles Muscle heads/tendons of origin: indicates how many tendons are present at less movable attachment o E.g., triceps brachii has three heads attaching by tendons to the skeleton 11

12 Clinical View: Intramuscular Injections One route of medication administration May be inserted into muscle with a syringe Medication to cardiovascular system through muscle s blood vessels Allows large amount of medication given at once Ensures slower and more uniform delivery than orally or intravenously Common sites: deltoid, gluteus medius, quadriceps 12

13 11.3a Muscles of Facial Expression Characteristics Insert into superficial fascia of skin of face Cause skin to move (facial expression) during contraction Most are innervated by facial nerve (CN VII) 13

14 11.3a Muscles of Facial Expression Muscles of forehead, scalp, and eyebrows Occipitofrontalis muscle o Connects with epicranial aponeurosis (galea aponeurotica) to form epicranius o Frontal belly raises eyebrows o Occipital belly retracts scalp slightly Corrugator supercilii muscle o Draws eyebrows together Orbicularis oculi o Circular muscle fibers surround orbit o Closes eye Levator palpebrae superioris o Elevates upper eyelid 14

15

16 11.3a Muscles of Facial Expression Muscles associated with the nose Nasalis o Elevates corners of the nostrils for flared nostrils Procerus o Wrinkles nose in distaste o Continuous with frontal belly of occipitofrontalis muscle 16

17 Procerus 10-17

18 11.3a Muscles of Facial Expression Muscles associated with the mouth Orbicularis oris o Closes mouth, puckers lips Depressor labii inferioris o Pulls lower lip inferiorly Depressor anguli oris o Pulls corners of the mouth inferiorly to frown Levator labii superioris o Pulls upper lip superiorly Levator anguli oris o Pulls corners of mouth superiorly and laterally o Works with zygomaticus major and minor in smiling 18

19 11.3a Muscles of Facial Expression Muscles associated with the mouth (continued) Risorius o Pulls corner of the lips laterally Mentalis o Protrudes lower lip Platysma o Tenses skin of neck and pulls lower lip inferiorly Buccinator o Compresses cheek against the teeth when chewing 19

20 Muscles of Facial Expression Figure 11.5a 20

21 Muscles of Facial Expression Figure 11.5b 21

22 Clinical View: Idiopathic Facial Nerve Paralysis (Bell Palsy) May be without known cause (idiopathic) Also known as Bell palsy Facial nerve inflamed and compressed Muscles on same side paralyzed Concern of eyes drying out and becoming damaged Prednisone often used to reduce swelling Level and timing of recovery varies 22

23 11.3b Extrinsic Eye Muscles Extrinsic eye muscles are extraocular Insert onto outer surface of the eye and move it Six muscles: four rectus and two oblique Rectus eye muscles originate from common tendinous ring Medial rectus pulls eye medially o Innervated by CN III (oculomotor) Lateral rectus pulls eye laterally o Innervated by CN VI (abducens) Inferior rectus pulls eye inferiorly and medially o Innervated by CN III (oculomotor) Superior rectus pulls eye superiorly and medially o Innervated by CN III (oculomotor) 23

24 11.3b Extrinsic Eye Muscles Oblique eye muscles Inferior oblique elevates and turns eye laterally o Innervated by CN III (oculomotor) Superior oblique depresses and turns the eye laterally o Passes through pulleylike loop, trochlea o Innervated by CN IV (trochlear) 24

25 Extrinsic Muscles of the Eye Figure 11.7a 25

26 Extrinsic Muscles of the Eye Figure 11.7b 26

27 Clinical View: Cranial III, IV, and VI Eye movements tested together with H-pattern Weakness (ptosis) of the eye in one direction can indicate cranial nerve involvement Double vision, Lazy eye, Cross eyed 27

28 11.3c Muscles of the Oral Cavity and Pharynx Muscles of mastication (chewing) Four paired muscles move mandible at temporomandibular joint (TMJ) All four are innervated by CN V (trigeminal) Temporalis o Elevates and pulls the mandible posteriorly (retracts) Masseter o Elevates and pulls the mandible anteriorly (protracts) o Most powerful and important masticatory muscle Medial and lateral pterygoid o Side to side movement of mandible o Medial pterygoid also helps with elevation of mandible o Lateral pterygoid helps with depression of the mandible 28

29 Muscles of Mastication Figure

30 11.3c Muscles of the Oral Cavity and Pharynx Muscles that move the tongue Left and right genioglossus o Protract (stick out) the tongue Left and right styloglossus o Elevate and retract the tongue Left and right hyoglossus o Depress and retract the tongue Left and right palatoglossus o Elevate posterior portion of the tongue 30

31 Muscles That Move the Tongue Figure

32 11.3d Muscles of the Anterior Neck: The Hyoid Muscles Suprahyroid muscles: above hyoid bone Elevate hyoid bone during swallowing or speaking Digastric: has two bellies, anterior and posterior o Also helps depress mandible Geniohyoid o Elevates the hyoid bone Mylohyoid o Provides muscular floor of mouth; also raises it up Stylohyoid: attaches to styloid process of temporal bone o Elongates oral cavity during swallowing 32

33 11.3d Muscles of the Anterior Neck: The Hyoid Muscles Infrahyoid muscles: inferior to hyoid bone Depress hyoid bone or thyroid cartilage of larynx as swallowing finishes Omohyoid o Depresses hyoid by pulling it toward scapula Sternohyoid o Depresses hyoid by pulling it toward sternum Sternothyroid o Depresses thyroid cartilage by pulling it toward sternum Thyrohyoid: extends from thyroid cartilage to hyoid o Depresses hyoid bone and elevates thyroid cartilage o Closes off larynx during swallowing 33

34 Muscles of the Anterior Neck Figure

35 11.3e Muscles That Move the Head and Neck Anterolateral neck muscles Generally act to flex neck Sternocleidomastoid: from sternum and clavicle to mastoid o Unilateral (one side) flexion of head to contracting muscle s side and contralateral rotation of head to opposite side Anterior, middle, and posterior scalene muscles Work with sternocleidomastoid to flex neck Pull cervical vertebrae toward 1 st and 2 nd ribs Elevate 1 st and 2 nd ribs during forced inhalation Tighten with paradoxical breathing 35

36 Muscles That Move the Head and Neck Figure

37 11.3e Muscles That Move the Head and Neck Posterior neck muscles Generally act to extend the neck Trapezius o Primary function is to help move pectoral girdle, but also helps extend neck Splenius capitis, splenius cervicis, semispinalis capitis, longissimus capitis o When contracted bilaterally, extend neck o When contracted unilaterally, turn head to same side Suboccipital muscles o Obliquus capitis superior, obliquus capitis inferior turn head to same side o Rectus capitis posterior major, rectus capitis posterior minor extend neck 37

38 Posterior Neck Muscles 38

39 Clinical View: Congenital Muscular Torticollis Newborn with shortened sternocleidomastoid May persist into childhood From birth trauma or prenatal position Head tilts to affected side and chin to unaffected side Treatments include Physical therapy Botulinum toxin, which impairs contraction of affected muscle Chiropractic care 39

40 What did you learn? Which muscles open and close the eyes? Which cranial nerve controls the lateral rectus muscle? What action does contraction of the masseter cause? What muscle is affected in Torticollis and what clinical presentation might be present? Copyright 2016 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education 40

41 11.4 Muscles of the Vertebral Column Muscles of the vertebral column Complex, multiple origins and insertions, overlapping muscles Erector spinae o Maintain upright posture; if bilaterally contracted, vertebral column extends o If unilaterally contracted, lateral flexion toward that side o Three groups of erector spinae muscles from lateral to medial Iliocostalis group Longissimus group Spinalis group Quadratus lumborum muscles o Extends vertebral column when bilaterally contracted o Laterally flexes column when unilaterally contracted o Located primarily in the lumbar region 41

42 Deep Muscles of the Vertebral Column Figure

43 11.5 Muscles of Respiration Muscles of respiration Diaphragm o Internally placed dome-shaped muscle that partitions thoracic and abdominal cavities o Most important muscle associated with breathing o Muscle fibers converge toward fibrous central tendon o Openings for vena cava, aorta, and esophagus o Contracts during inspiration o Central tendon pulled inferiorly, increasing dimension of thoracic cavity 43

44 Muscles of Respiration Figure 11.15c-d 44

45 11.5 Muscles of Respiration Muscles of respiration External intercostals o Elevate ribs during inspiration, expanding cavity Internal intercostals o Deep to external intercostals o Fibers at right angles to external intercostals o Depress ribs during forced expiration Transversus thoracis o Depresses ribs during forced expiration 45

46 Muscles of Respiration Figure 11.15a 46

47 11.6 Muscles of the Abdominal Wall Muscles of the abdominal wall Compress and hold abdominal organs in place External oblique o Ipsilateral flexion and Contralateral rotation Internal oblique o Ipsilateral flexion and Ipsilateral rotation Transversus abdominis o Stabilizes the vertebral column (core muscle) Rectus abdominis o Partitioned into four segments by fibrous tendinous intersections o Enclosed within fibrous sleeve, rectus sheath Formed from aponeuroses of external and internal oblique, transversus abdominis Rectus sheaths of two sides connected by fibrous strip, linea alba 47

48 Muscles of the Abdominal Wall Figure 11.16a 48

49 Muscles of the Abdominal Wall Figure 11.16b 49

50 Portion of viscera protrudes through weak point of abdominal wall Inguinal hernia Clinical View: Hernias Loop of small intestine protrudes through superficial inguinal ring More likely to occur in males since their inguinal canals are larger to accommodate spermatic cord High abdominal pressure (e.g., straining to lift something heavy) can push intestine into canal Physicians test for it by palpating inguinal ring while patient coughs (cough raises abdominal pressure) 50

51 Perineum Muscles of the Pelvic Floor Diamond-shaped region between lower appendages Bounded by pubic symphysis, coccyx, ischial tuberosities Contains two triangles divided by transverse line between ischial tuberosities o Urogenital triangle contains external genitalia and urethra o Anal triangle contains anus Figure 11.17b,c (left) 51

52 11.8a Muscles That Move the Pectoral Girdle Anterior thoracic muscles Pectoralis minor o Deep to pectoralis major o Helps depress and protract scapula; hunches shoulders Serratus anterior o Fan-shaped muscle between ribs and scapula o Protracts, stabilizes scapula Subclavius o Extends from clavicle to first rib o Stabilizes and depresses scapula 52

53 Muscles That Move Pectoral Girdle and Arm Figure 11.21a 53

54 11.8a Muscles That Move the Pectoral Girdle Posterior thoracic muscles Levator scapulae o Attaches to cervical vertebrae and scapula Tends to be involved in tension headaches o Elevates and inferiorly rotates the scapula Rhomboid major and minor o Runs inferolaterally from vertebrae to scapula, deep to trapezius o Helps elevate, retract, and inferiorly rotate the scapula Trapezius o Diamond-shaped muscle extending from skull and vertebral column to pectoral girdle o Can elevate, depress, retract, or rotate scapula 54

55 Muscles That Move Pectoral Girdle and Arm Figure 11.21b 55

56 Actions of Some Thoracic Muscles on the Scapula Figure 11.20a 56

57 11.8b Muscles That Move the Glenohumeral Joint/Arm Eleven muscles cross the glenohumeral joint and move the humerus Deltoid o Prime abductor of the arm o Its anterior fibers flex and medially rotate arm o Its lateral fibers abduct the arm o Its posterior fibers extend and laterally rotate arm Latissimus dorsi o Prime arm extensor; adducts, medially rotates Pectoralis major o Prime arm flexor; adducts, medially rotates Coracobrachialis o Flexes and adducts the arm 57

58 Triceps brachii 11.8b Muscles That Move the Glenohumeral Joint/Arm o Helps extend and adduct the arm Biceps brachii o Assists in flexing the arm Teres major Extends, adducts, medially rotates arm Rotator cuff muscles Subscapularis o Medially rotates arm Supraspinatus o Abducts the arm Infraspinatus and teres minor o Adduct and laterally rotate arm 58

59 Rotator Cuff Muscles Subscapularis helps in wind up for pitch Supraspinatus helps in executing pitch delivery Infraspinatus and teres minor slow the arm at end of pitch Figure

60 Clinical View: Rotator Cuff Injuries Result of trauma or disease Can be caused by repetitive use Can be caused by falling on the shoulder or lifting too heavy of an object Supraspinatus most commonly involved Symptoms are swelling, tenderness, and pain with movement Especially common in baseball players May require physical therapy or surgical repair 60

61 11.8c Arm and Forearm Muscles That Move the Elbow Joint/Forearm Muscles of the arm s anterior compartment Biceps brachii o Two-headed muscle on anterior humerus o Flexes and supinates forearm; weakly helps flex humerus Brachialis o Deep to biceps brachii o Most powerful flexor of forearm (prime mover) Brachioradialis o Located on anterolateral forearm o Synergist in elbow flexion 61

62 Anterior Muscles with Actions at Elbow Figure

63 11.8c Arm and Forearm Muscles That Move the Elbow Joint/Forearm Muscles of the arm s posterior compartment Triceps brachii o Large three-headed muscle on posterior arm o Major extensor of forearm; also helps extend humerus Anconeus o Weak elbow extensor (synergist) o Crosses posterolateral region of elbow 63

64 Posterior Muscles with Actions at Elbow Figure

65 11.8c Arm and Forearm Muscles That Move the Elbow Joint/Forearm Muscles of the forearm that act on the elbow joint Pronator teres and pronator quadratus o Rotate the radius across the ulna to pronate forearm o Located in anterior compartment of forearm Supinator o Supinates forearm o Located in posterior compartment of forearm 65

66 Forearm Muscles That Supinate or Pronate Figure

67 11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers Muscles of the forearm s anterior compartment Muscles originate on medial epicondyle Flexor carpi radialis o Flexes wrist and abducts hand Palmaris longus o Weakly assists in wrist flexion Flexor carpi ulnaris o Flexes wrist and adducts hand Flexor digitorum superficialis o Flexes wrist, MP, and proximal interphalangeal (PIP) joints of fingers 2 5 Flexor digitorum profundus o Flexes wrist, MP joints, PIP joints, and distal interphalangeal (DIP) joints of fingers

68 Anterior Forearm Muscles Figure 11.27a 68

69 Anterior Forearm Muscles Figure 11.27b-c 69

70 11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers Muscles of forearm s posterior compartment Muscles originate from lateral epicondyle Extensor carpi radialis longus/brevis o Extends wrist and abducts hand Extensor digitorum o Extends wrist, MP joints, PIP joints, and DIP joints of fingers 2 5 Extensor digit minimi o Extends the little finger Extensor carpi ulnaris o Extends wrist and adducts hand Extensor pollicis longus/brevis o Helps extend MP joint of the thumb Extensor indicis o Extends MP, PIP, and DIP joints of index finger 70

71 Posterior Forearm Muscles Figure 11.29a 71

72 Posterior Forearm Muscles Figure 11.29b 72

73 Clinical View: Lateral Epicondylitis or Medial Epicondylitis Lateral Epicondylitis Also known as tennis elbow From trauma or overuse of common extensor tendon of posterior forearm muscles Pain at lateral epicondyle of humerus often results from repeated forceful contraction of forearm extensors Medial Epicondylitis Also known as golfers elbow From trauma or overuse of common flexor tendon of anterior forearm muscles Pain at medial epicondyle of humerus often results from repeated forceful contraction of forearm flexors 73

74 11.8d Forearm Muscles That Move the Wrist Joint, Hand, and Fingers Retinacula of the forearm Fibrous bands at the wrist formed from deep fascia Hold tendons close to bone Flexor retinaculum covers palmar surface of carpal bones o Carpal tunnel: tight space between bones and flexor retinaculum through which flexor tendons pass Extensor retinaculum superficial to dorsal surface of carpal bones o Extensor tendons of wrist and digits pass under it 74

75 Clinical View: Carpal Tunnel Syndrome Carpal tunnel Space between carpal bones and flexor retinaculum Flexor tendons extending through tunnel Median nerve extending through tunnel Syndrome caused by compression of nerve Characterized by pain and pins and needles (paresthesia) 75

76 11.8e Intrinsic Muscles of the Hand Intrinsic muscles of the hand: originate and insert in hand Thenar group: form fleshy mass at base of thumb Flexor pollicis brevis: flexes thumb Abductor pollicis brevis: abducts thumb Opponens pollicis: assists in opposition of thumb Hypothenar group: smaller fleshy mass at base of little finger Flexor digiti minimi brevis: flexes little finger Abductor digiti minimi: abducts little finger Opponens digiti minimi: assists in opposition of little finger 76

77 Intrinsic Muscles of the Hand Figure 11.30a 77

78 What did you learn? Which four muscles make up the rotator cuff? In which anatomical compartment is the brachialis muscle found? What action is typically performed by muscles in the anterior compartment of the forearm? Which part of the hand makes up the thenar group of muscles? What structure of the forearm is involved in carpal tunnel syndrome? 78

79 11.9a Muscles that Move the Hip Joint/Thigh How are thigh muscles organized? They are bound by the fascia lata, deep fascia that partitions them into compartments Anterior compartment muscles o Extend the knee or flex the thigh Medial compartment muscles o Adduct the thigh Lateral compartment muscle o Abducts the thigh Posterior compartment muscles o Flex knee and extend the thigh 79

80 11.9a Muscles that Move the Hip Joint/Thigh Muscles inserting on anterior thigh Psoas major and iliacus (collectively, iliopsoas) o Run from lumbar vertebrae and ilium to femur o Flex the thigh Sartorius tailor muscle o Flex and laterally rotate the thigh and flex the knee Quadriceps femoris: composite muscle with four heads o Consists of: rectus femoris, vastus lateralis, vastus medialis, vastus intermedius o Prime mover of knee extension o Pulls on quadriceps tendon, which becomes patellar ligament to tibia 80

81 Muscles of Anterior Thigh Figure 11.32a 81

82 11.9a Muscles that Move the Hip Joint/Thigh Muscles of the medial compartment of thigh Innervated by the obturator nerve Adductor longus, adductor brevis, gracilis, pectineus Adductor magnus Muscle of lateral thigh Tensor fasciae latae o Attaches to iliotibial tract (lateral thickening of fascia lata) o Abducts and medially rotates the thigh 82

83 Muscles That Act on the Hip and Thigh Figure 11.31a 83

84 Muscles That Act on the Hip and Thigh Figure 11.31b 84

85 11.9a Muscles That Move the Hip Joint/Thigh Muscles of the posterior thigh Gluteus maximus o Chief extensor of the thigh; also laterally rotates the thigh Gluteus medius and gluteus minimus o Deep to gluteus maximus o Abduct and medially rotate the thigh Hamstrings: group of 3 muscles o Biceps femoris, semimembranosous, semitendinosus o Extend the thigh (also rotate the knee) Group of muscles deep to gluteal muscles o Piriformis, superior gemellus, obturator internus, obturator externus, inferior gemellus, and quadratus femoris o Laterally rotate the thigh 85

86 Muscles of Gluteal Region and Posterior Thigh Figure 11.33a 86

87 Muscles That Act on the Hip and Thigh Figure 11.31c 87

88 Clinical View: Iliotibial Band Syndrome and Hamstring Strain Iliotibial Band Syndrome Both the Gluteus medius and Tensor fascia latae muscles insert on the iliotibial band Band runs from the lateral hip to the knee Pain and inflammation at the lateral knee due to friction from tightening of this band Hamstring Strain Muscle overload when the hamstring muscle undergoes eccentric contraction Sprinters, basketball players, football players, soccer players 88

89 11.9c Leg Muscles That Move the Ankle, Foot, and Toes Crural muscles: muscles located in leg that move ankle, foot, toes Partitioned into anterior, lateral, and posterior compartments 89

90 11.9c Leg Muscles That Move the Ankle, Foot, and Toes Muscles of the leg s anterior compartment Extensor digitorum longus o Dorsiflexes the foot and extends toes 2 5 Extensor hallucis longus o Dorsiflexes the foot and extends the great toe Fibularis tertius o Dorsiflexes and weakly everts the foot Tibialis anterior o Primary dorsiflexor of the foot; also inverts the foot Extensor retinaculum o Thickening of fascia at ankle that holds tendons close to bones 90

91 Muscles of the Anterior Leg Figure 11.34a 91

92 11.9c Leg Muscles That Move the Ankle, Foot, and Toes Muscles of the leg s lateral compartment Both are powerful foot evertors, weak plantar flexors o Fibularis longus: inserts on plantar side of foot o Fibularis brevis: lies deep to fibularis longus, inserts onto base of 5 th metatarsal 92

93 Muscles of the Lateral Leg Figure 11.35a 93

94 11.9c Leg Muscles That Move the Ankle, Foot, and Toes Muscles of the leg s posterior compartment Superficial layer Gastrocnemius o Has two bellies; forms calf o Flexes the leg and plantar flexes the foot Soleus o Broad muscle deep to gastrocnemius o Plantar flexes the foot Triceps surae = gastrocnemius + soleus o Insert at heel with calcaneal tendon Plantaris o Weak leg flexor and plantar flexor of the foot 94

95 11.9c Leg Muscles That Move the Ankle, Foot, and Toes Muscles of the leg s posterior compartment (continued) Deep layer Flexor digitorum longus o Flexes the foot and the MP, PIP and DIP of joints 2 5 Flexor hallucis longus o Flexes the foot and great toe Tibialis posterior o Plantar flexes and inverts the foot Popliteus o Flexes the leg and medially rotates the tibia (lock the knee) 95

96 Muscles of the Posterior Leg Figure 11.36a-b 96

97 Clinical View: Shin Splints, Tarsal Tunnel Syndrome, and Achilles Tendon Rupture Shin splints Soreness along length of tibia Often occur in new poorly conditioned runners May be considered a type of compartment syndrome Tarsal Tunnel syndrome Tension of the flexor retinaculum at the medial compartment of the foot leading to posterior tibial nerve compression Pain at the medial side of the ankle and into the heel/foot Common in overpronation Achilles tendon rupture Common in sports that involve running, jumping, pivoting, or rapid push off 97

98 11.9d Intrinsic Muscles of the Foot Intrinsic muscles of the foot originate and insert within foot Support the arches, move the toes Dorsal group Extensor hallucis brevis o Extends the MP joint of the great toe Extensor digitorum brevis o Extends the MP and PIP joints of toes

99 11.9d Intrinsic Muscles of the Foot Plantar group Supported by aponeurosis formed from deep fascia o Extends between phalanges of toes and calcaneus Muscles grouped into four layers from superficial to deep 1. Flexor digitorum brevis, abductor hallucis, abductor digiti minimi 2. Quadratus plantae, lumbricals 3. Adductor hallucis, flexor hallucis brevis, flexor digiti minimi brevis 4. Dorsal interossei, plantar interossei 99

100 Plantar Intrinsic Muscles of the Foot Figure 11.37a-c 100

101 Plantar Intrinsic Muscles of the Foot Figure 11.37d-e 101

102 Clinical View: Plantar Fasciitis Inflammation of the plantar aponeurosis Associated with overexertion that stresses the fascia E.g., weight bearing activities, excessive body weight, poor shoes, poor biomechanics Pain when stepping down from bed in the morning 102