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Chapter 10

Chapter 10. The Muscular System. Structural and functional organization of muscles Muscles of the head and neck Muscles of the trunk Muscles acting on the shoulder and upper limb Muscles acting on the hip and lower limb. Organization of Muscles. 600 Human skeletal muscles

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Chapter 10

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  1. Chapter 10

  2. The Muscular System • Structural and functional organization of muscles • Muscles of the head and neck • Muscles of the trunk • Muscles acting on the shoulder and upper limb • Muscles acting on the hip and lower limb

  3. Organization of Muscles • 600 Human skeletal muscles • General structural and functional topics • muscle shape and function • connective tissues of muscle • coordinated actions of muscle groups • intrinsic and extrinsic muscles • muscle innervation • Regional descriptions

  4. The Functions of Muscles • Movement of body parts and organ contents • Maintain posture and prevent movement • Communication - speech, expression and writing • Control of openings and passageways • Heat production

  5. Connective Tissues of a Muscle Tendon Deep fascia Epimysium Perimysium Endomysium

  6. Connective Tissues of a Muscle • Epimysium • covers whole muscle belly • blends into CT between muscles • Perimysium • slightly thicker layer of connective tissue • surrounds bundle of cells called a fascicle • Endomysium • thin areolar tissue around each cell • allows room for capillaries and nerve fibers

  7. Location of Fascia • Deep fascia • found between adjacent muscles • Superficial fascia (hypodermis) • adipose between skin and muscles Superficial Fascia Deep Fascia

  8. Muscle Attachments • Direct (fleshy) attachment to bone • epimysium is continuous with periosteum • intercostal muscles • Indirect attachment to bone • epimysium continues as tendon or aponeurosis that merges into periosteum as perforating fibers • biceps brachii or abdominal muscle • Attachment to dermis • Stress will tear the tendon before pulling the tendon loose from either muscle or bone

  9. Parts of a Skeletal Muscle • Origin • attachment to stationary end of muscle • Belly • thicker, middle region of muscle • Insertion • attachment to mobile end of muscle

  10. Skeletal Muscle Shapes 1

  11. Skeletal Muscle Shapes 2 • Fusiform muscles • thick in middle and tapered at ends • biceps brachii m. • Parallel muscles have parallel fascicles • rectus abdominis m. • Convergent muscle • broad at origin and tapering to a narrower insertion • Pennate muscles • fascicles insert obliquely on a tendon • unipennate, bipennate or multipennate • palmar interosseus, rectus femoris and deltoid • Circular muscles • ring around body opening • orbicularis oculi

  12. Coordinated Muscle Actions • Prime mover or agonist • produces most of force • Synergist aids the prime mover • stabilizes the nearby joint • modifies the direction of movement • Antagonist • opposes the prime mover • preventing excessive movement and injury • Fixator • prevents movement of bone

  13. Muscle Actions during Elbow Flexion • Prime mover (agonist) = brachialis • Synergist = biceps brachii • Antagonist = triceps brachii • Fixator = muscle that holds scapula firmly in place • rhomboideus m.

  14. Intrinsic and Extrinsic Muscles • Intrinsic muscles are contained within a region such as the hand. • Extrinsic muscles move the fingers but are found outside the region.

  15. Skeletal Muscle Innervation • Cranial nerves arising from the brain • exit the skull through foramina • numbered I to XII • Spinal nerves arising from the spinal cord • exit the vertebral column through intervertebral foramina

  16. How Muscles are Named • Nomina Anatomica • system of Latin names developed in 1895 • updated since then • English names for muscles are slight modifications of the Latin names. • Table 10.1 = terms used to name muscles • levator = elevates a body part • profundus = deepest • quadriceps = having 4 heads

  17. Learning Strategy • Explore the location, origin, insertion and innervation of 160 skeletal muscles • use tabular information in this chapter. • Increase your retention • examining models and atlases • palpating yourself • observe an articulated skeleton • say the names aloud and check your pronunciation

  18. The Muscular System

  19. Muscles of Facial Expression • Small muscles that insert into the dermis • 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

  20. Muscles in Facial Expression 1

  21. Muscles in Facial Expression 2

  22. Musculature of the Tongue • Intrinsic muscles = vertical, transverse and longitudinal • Extrinsic muscles connect tongue to hyoid, styloid process, palate and inside of chin • Tongue shifts food onto teeth and pushes it into pharynx Intrinsic tongue muscles Extrinsic tongue muscles

  23. Muscles of Mastication • 4 Major muscles • Arise from skull and insert on mandible • Temporalis and Masseter elevate the mandible • Medial and Lateral Pterygoids help elevate, but produce lateral swinging of jaw Temporalis Masseter Lateral pterygoid Medial pterygoid

  24. Suprahyoid Muscles and Swallowing • Digastric and Mylohyoid = open mouth • Geniohyoid = widens pharynx during swallowing • Stylohyoid = elevates hyoid • Thyrohyoid = elevates larynx, closing glottis Mylohyoid Digastric Thyrohyoid

  25. Triangles of the Neck

  26. Muscles involved in Swallowing • Pharyngeal constrictors push food down throat • Infrahyoid muscles pulls larynx downward • Intrinsic laryngeal muscles control speech Pharyngeal constrictors

  27. Muscles of Respiration • Breathing requires the use of muscles • Diaphragm and external intercostal muscles • internal intercostal muscles • Contraction of first 2 produces inspiration • Contraction of last produces forced expiration • Normal expiration requires little muscular activity • elastic recoil and gravity collapses the chest • inspiratory muscles active in braking action, so exhalation is smooth

  28. Muscles of Respiration -- Diaphragm Central tendon • Muscular dome between thoracic and abdominal cavities • Muscle fascicles extend to a fibrous central tendon • Contraction flattens it • increases the vertical dimension of the thorax drawing air into the lungs • raises the abdominal pressure to help expel urine, feces and facilitating childbirth

  29. Muscles of Respiration - Intercostals • External intercostals • extend downward and anteriorly from rib to rib • pull ribcage up and outward during inspiration • Internal intercostals • extend upward and anteriorly from rib to rib • pull ribcage downward during forced expiration

  30. Muscles of the Abdomen • 4 Pairs of sheetlike muscles • external oblique • internal oblique • transverse abdominis • rectus abdominis • Functions • support the viscera • stabilize the vertebral column • help in respiration, urination, defecation and childbirth

  31. External oblique superficial downward anteriorly inguinal ligament Rectus abdominis vertical, straplike tendinous intersections rectus sheath linea alba Rectus Abdominis and External Oblique Rectus abdominis External oblique

  32. Internal oblique anteriorly upwards Transverse abdominal horizontal fiber orientation deepest layer Internal Oblique -Transverse Abdominis Transverse abdominis Internal oblique

  33. Superficial Muscles of Back Semispinalis SpleniusLevator scapulaeRhomboideus Supraspinatus Infraspinatus Teres major Gluteus maximus Gluteus medius Trapezius Latissimus dorsi

  34. Muscles of the Back • Erector spinae group • 3 columns muscle • from sacrum to ribs • extends vertebral column • Semispinalis group • vertebrae to vertebrae • extends neck • Multifidis • vertebrae to vertebrae • rotates vertebral column • Quadratus lumborum • ilium to 12th rib • lateral flexion Semispinalis Erector spinae Multifidis Quadratus lumborum

  35. Muscles of the Pelvic Floor • 3 Layers of muscles span pelvic outlet • support pelvic viscera • Region is called perineum • diamond-shaped region bounded by pubic symphysis, coccyx and ischial tuberosities • penetrated by anal canal, urethra and vagina • anteriorly = urogenital triangle; posteriorly= anal triangle • 3 Layers or compartments of the perineum • superficial layer = Superficial perineal space • middle layer = Urogenital diaphragm and Anal sphincter • deep layer = Pelvic diaphragm

  36. Superficial Perineal Space • 3 Muscles found just deep to the skin • Ischiocavernosus = arises ischial and pubic ramus • Bulbospongiosus = covers bulb of penis or encloses vagina • Function during intercourse and voiding of urine

  37. Muscles of UG diaphragm • Middle layer of pelvic floor contains urogenital diaphragm and external anal sphincter • Urogenital diaphragm = 2 muscles • deep transverse perineus m. supports pelvic viscera • external urethral sphincter m. inhibits urination

  38. Muscles of Pelvic Diaphragm Levator ani Coccygeus • Deepest compartment of the perineum • Pelvic diaphragm = 2 muscles • levator ani m. supports viscera and defecation • coccygeus m. supports and elevates pelvic floor

  39. Hernias • Protrusion of viscera through muscular wall of 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

  40. Muscles on Pectoral Girdle • Originate on axial skeleton and insert onto clavicle or scapula • Anterior muscle group = 2 muscles • Posterior muscle group = 4 muscles • Scapular movements produced include • medial and lateral rotation of the scapula • elevation and depression of the scapula • protraction and retraction of the scapula • Clavicle braces the shoulder and limits movement

  41. Pectoralis Minor ribs 3-5 to coracoid process of scapula protracts and depresses scapula lifts ribs during forced expiration Serratus Anterior ribs 1-9 to medial border of scapula abducts and rotates or depresses scapula throwing muscle Anterior Scapular Muscles

  42. Muscles Acting on Scapula

  43. Posterior Scapular Muscles • 4 Muscles • superficial = Trapezius • deep = Rhomboids and Levator scapulae • Trapezius • rotate scapula upward • retract scapula • depress scapula • With Levator scapulae and Rhomboids elevates scapula • With Serratus anterior depresses scapula

  44. Rhomboideus mm. medial border of scapula to C7-T1 Levator scapulae from superior angle of scapula to C1-C4 Posterior Scapular Muscles

  45. Muscles Acting on Humerus • Crossing shoulder joint to humerus • 2 arise from axial skeleton • prime movers in flexion and extension • arise from sternum and clavicle or T7-L5 and ilium Pectoralis major Latissimus dorsi

  46. Muscles Acting on Humerus • Arise from scapula • Deltoid is prime mover • flexion, extension and abduction of humerus • Coracobrachialisassists in flexion • Teres major assists in extension • Remaining 4 form the rotator cuff muscles that reinforce the shoulder joint capsule

  47. Posterior View of Cadaver Chest

  48. Extending from posterior scapula to humerus supraspinatus infraspinatus teres minor Extending from anterior scapula to humerus subscapularis Rotator Cuff Muscles Subscapularis Supraspinatus Infraspinatus All 4 help reinforce joint capsule.

  49. Rotator Cuff Muscles

  50. Anterior View of Cadaver Chest

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