Transcript Chapter 10
Chapter 10 *Lecture PowerPoint The Muscular System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction • Facts about muscles – Muscles constitute nearly half of the body’s weight and occupy a place of central interest in several fields of health care and fitness • Physical and occupational therapy, athletes, dancers, trainers, acrobats, nurses, and more – Muscular system is closely related to other systems covered previously – Chapters 11 and 12 will examine the mechanisms of muscle contraction at the cellular and molecular levels • Three kinds of muscle tissue – Skeletal, cardiac, smooth 10-2 Introduction • In this chapter we will cover: – 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 Figure 10.5 10-3 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. 10-4 The Structural and Functional Organization of Muscles Cont. – 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. 10-5 The Structural and Functional Organization of Muscles • About 600 human skeletal muscles • Constitute about half of our body weight • Specialized for one major purpose – Converting the chemical energy in ATP into the mechanical energy of motion • Myology—the study of the muscular system 10-6 The Functions of Muscles • Movement – Move from place to place, movement of body parts and body contents in breathing, circulation, feeding and digestion, defecation, urination, and childbirth • Stability – Maintain posture by preventing unwanted movements – Antigravity muscles: resist pull of gravity and prevent us from falling or slumping over – Stabilize joints • Role in communication: speech, writing, nonverbal communications 10-7 The Functions of Muscles • Control of openings and passageways – Sphincters: internal muscular rings that control the movement of food, bile, blood, and other materials within the body • Heat production by skeletal muscles – As much as 85% of our body heat • Glycemic control – Regulation of blood glucose concentrations within its normal range by storing glycogen 10-8 Connective Tissues of a Muscle Copyright © The McGraw-Hill Companies, Inc. 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Tendon Fascia Skeletal muscle Muscle fascicle Nerve Blood vessels Epimysium Figure 10.1a Perimysium Endomysium Muscle fiber Muscle fascicle Perimysium Muscle fiber (a) 10-9 Connective Tissues and Fascicles • Endomysium – Thin sleeve of loose connective tissue surrounding each muscle fiber – Allows room for capillaries and nerve fibers to reach each muscle fiber – Provides extracellular chemical environment for the muscle fiber and its associated nerve ending • Perimysium – Slightly thicker layer of connective tissue – Fascicles: bundles of muscle fibers wrapped in perimysium – Carry larger nerves and blood vessels, and stretch receptors 10-10 Connective Tissues and Fascicles • Epimysium – Fibrous sheath surrounding the entire muscle – Outer surface grades into the fascia – Inner surface sends projections between fascicles to form perimysium • Fascia – Sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue 10-11 Connective Tissues of a Muscle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Perimysium Endomysium Muscle fiber, c.s. Fascicle, c.s. Muscle fiber, l.s. Fascicle, l.s. (c) Victor Eroschenko Figure 10.1c 10-12 Fascicles and Muscle Shapes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Unipennate Triangular Bipennate Parallel Multipennate Fusiform Tendon Circular Belly Pectoralis major Tendon Palmar interosseous Rectus femoris Rectus abdominis Biceps brachii Deltoid Figure 10.2 Orbicularis oculi • Strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles 10-13 Muscle Compartments Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior Lateral Medial Posterior Key Anterior compartment Lateral compartment Posterior compartment, deep layer Posterior compartment, superficial layer Tibia Fibula Interosseous membrane Artery, veins, and nerve Intermuscular septa Fasciae Subcutaneous fat Figure 10.3 • A group of functionally related muscles enclosed and separated from others by connective tissue fascia • Contains nerves, blood vessels that supply the muscle group – Thoracic, abdominal walls, pelvic floor, limbs • Intermuscular septa separate one compartment from another 10-14 Muscle Attachments • Indirect attachment to bone – Tendons bridge the gap between muscle ends and bony attachment • Collagen fibers of the endo-, peri-, and epimysium continue into the tendon • From there into the periosteum and the matrix of bone • Very strong structural continuity from muscle to bone • Biceps brachii, Achilles tendon • Aponeurosis—tendon is a broad, flat sheet (palmar aponeurosis) • Retinaculum—connective tissue band that tendons from separate muscles pass under 10-15 Muscle Attachments • Direct (fleshy) attachment to bone – Little separation between muscle and bone – Muscle seems to immerge directly from bone • Margins of brachialis, lateral head of triceps brachii 10-16 Muscle Origins and Insertions • Origin – Bony attachment at stationary end of muscle Copyright © The McGraw-Hill Companies, Inc. 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Origins Origins Humerus Scapula • Belly – Thicker, middle region of muscle between origin and insertion Bellies Extensors: Triceps brachii Long head Flexors: Biceps brachii Brachialis Lateral head • Insertion – Bony attachment to mobile end of muscle Insertion Radius Ulna Insertion Figure 10.4 10-17 Muscle Origin and Insertions • Also can be determined by proximal or distal or superior and inferior attachments, especially on limbs • Some muscles insert not on bone but on the fascia or tendon of another muscle or on collagen fibers of the dermis – Distal tendon of the biceps brachii inserts on the fascia of the forearm – Facial muscles insert in the skin 10-18 Functional Groups of Muscles • Action—the effects produced by a muscle – To produce or prevent movement • Four categories depending on action – Prime mover (agonist) • Muscle that produces most of force during a joint action – Synergist: muscle that aids the prime mover • Stabilizes the nearby joint • Modifies the direction of movement 10-19 Functional Groups of Muscles Cont. – Antagonist: opposes the prime mover • Relaxes to give prime mover control over an action • Preventing excessive movement and injury • Antagonistic pairs—muscles that act on opposite sides of a joint – Fixator: muscle that prevents movement of bone 10-20 Functional Groups of Muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Prime mover—brachialis Origins Origins Humerus Scapula • Synergist—biceps brachii Bellies Extensors: Triceps brachii Long head Flexors: Biceps brachii • Antagonist—triceps brachii Brachialis Lateral head • Fixator—muscle that holds scapula firmly in place Insertion Radius Ulna Insertion – Rhomboids Figure 10.4 10-21 Intrinsic and Extrinsic Muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Common flexor tendon Flexor digitorum superficialis Flexor pollicis longus Flexor digitorum superficialis tendons Flexor digitorum profundus tendons (b) Intermediate flexor Figure 10.28b • Intrinsic muscles— entirely contained within a region, such as the hand – Both its origin and insertion there Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tendon sheath First dorsal interosseous Tendon of flexor digitorum profundus Adductor pollicis Tendon of flexor digitorum superficialis Tendon of flexor pollicis longus Lumbricals Opponens digiti minimi Flexor pollicis brevis Flexor digiti Abductor pollicis brevis Abductor digiti minimi • Extrinsic muscles— act on a designated region, but has its origin elsewhere – Fingers: extrinsic muscles in the forearm Opponens pollicis Flexor retinaculum Tendons of: Abductor pollicis longus Flexor carpi radialis Flexor pollicis longus Tendons of: Flexor carpi ulnaris Flexor digitorum superficialis Palmaris longus (a) Palmar aspect, superficial Figure 10.31a 10-22 Muscle Innervation • Innervation of a muscle—refers to the identity of the nerve that stimulates it – Enables the diagnosis of nerve, spinal cord, and brainstem injuries from their effects on muscle function • Spinal nerves arise from the spinal cord – – – – Emerge through intervertebral foramina Immediately branch into a posterior and anterior ramus Innervate muscles below the neck Plexus: weblike network of spinal nerves adjacent to the vertebral column 10-23 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 10-24 Blood Supply • Muscular system receives about 1.25 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 threequarters (11.5 L/min) • Capillaries branch extensively through the endomysium to reach every muscle fiber 10-25 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 10-26 The Muscular System Copyright © The McGraw-Hill Companies, Inc. 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Superficial Deep Deep Superficial Frontalis Orbicularis oculi Occipitalis Masseter Zygomaticus major Orbicularis oris Sternocleidomastoid Platysma Trapezius Pectoralis minor Deltoid Coracobrachialis Pectoralis major Serratus anterior Brachialis Biceps brachii Flexor digitorum profundus Flexor pollicis longus Transverse abdominal External abdominal oblique Tensor fasciae latae Infraspinatus Teres minor Teres major Triceps brachii Triceps brachii (cut) Supinator Flexor carpi radialis Trapezius Serratus anterior Rectus abdominis Brachioradialis Semispinalis capitis Sternocleidomastoid Splenius capitis Levator scapulae Supraspinatus Rhomboideus minor Rhomboideus major Deltoid (cut) Infraspinatus Internal abdominal oblique Pronator quadratus Latissimus dorsi Extensor carpi radialis longus and brevis External abdominal oblique Extensor digitorum Gluteus medius Extensor carpi ulnaris Gluteus maximus Serratus posterior inferior External abdominal oblique Internal abdominal oblique Erector spinae Flexor carpi ulnaris Extensor digitorum (cut) Gluteus minimus Lateral rotators Adductor magnus Adductor longus Sartorius Adductors Rectus femoris Vastus lateralis Vastus lateralis Vastus intermedius Gracilis Vastus medialis Gracilis Iliotibial band Semimembranosus Biceps femoris Semitendinosus Iliotibial band Biceps femoris Gastrocnemius (cut) Soleus (cut) Fibularis longus Gastrocnemius Tibialis anterior Soleus Extensor digitorum longus Extensor digitorum longus Gastrocnemius Tibialis posterior Flexor digitorum longus Soleus Extensor hallucis longus Fibularis longus Calcaneal tendon Figure 10.5a Figure 10.5b (a) Anterior view (b) Posterior view 10-27 A Learning Strategy • Examine models, cadavers, dissected animals, or a photographic atlas to get visual images of the muscle • When studying a particular muscle, palpate it on yourself if possible • Locate origins and insertions of muscles on an articulated skeleton 10-28 A Learning Strategy • 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 10-29 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 10-30 Compartment Syndrome • Fasciae of arms and legs enclose muscle compartments very snugly • If a blood vessel in a compartment is damaged, blood and tissue fluid accumulate in the compartment • Fasciae prevent compartment from expanding with increasing pressure • Compartment syndrome—mounting pressure on the muscles, nerves, and blood vessels triggers a sequence of degenerative events – Blood flow to compartment is obstructed by pressure 10-31 Compartment Syndrome Cont. – 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) 10-32 Carpal Tunnel Syndrome • Flexor retinaculum—bracelet-like fibrous sheet, which the flexor tendons of the extrinsic muscles that flex the wrist pass on their way to their insertions • 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 10-33 Carpal Tunnel Syndrome • Carpal tunnel syndrome—prolonged, repetitive motions of wrist and fingers can cause tissues in the carpal tunnel to become inflamed, swollen, or fibrotic – Puts pressure on the median nerve of the wrist that passes through the carpal tunnel along with the 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 10-34 Carpal Tunnel Syndrome Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Repetitive motions cause inflammation and pressure on median nerve Tendon of flexor digitorum superficialis Lumbrical Opponens digiti minimi Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Adductor pollicis Flexor digiti minimi brevis Flexor pollicis brevis Abductor digiti minimi Abductor pollicis brevis Pisiform bone Tendon of extensor pollicis brevis Tendon sheath First dorsal interosseous Tendon of flexor digitorum profundus Adductor pollicis Tendon of flexor digitorum superficialis Lumbricals Opponens digiti minimi Flexor pollicis brevis Flexor digiti minimi brevis Flexor digitorum superficialis Tendon of flexor carpi radialis Abductor pollicis brevis Abductor digiti minimi Opponens pollicis Flexor retinaculum (b) Palmar dissection, superficial Figure 10.31b Tendon of flexor pollicis longus Tendons of: Flexor carpi ulnaris Flexor digitorum superficialis Palmaris longus Tendons of: Abductor pollicis longus Flexor carpi radialis Flexor pollicis longus (a) Palmar aspect, superficial Figure 10.31a 10-35 Common Athletic Injuries • Muscles and tendons are vulnerable to sudden and intense stress • Proper conditioning and warm-up needed • Common injuries include: – – – – – – Compartment syndrome Shinsplints Pulled hamstrings Tennis elbow Pulled groin Rotator cuff injury • Treat with rest, ice, compression, and elevation • “No pain, no gain” is a dangerous misconception 10-36