Lect 10 Skeletal System Part I II Short version FA 20 PDF

CLICKER TIME……………… The approximate number of skeletal muscles in the body is a. 350 b. 500 c. 645 d. 715  Chapter 10 MUSCULAR SYSTEM Part One MUSCULAR TISSUE  Muscular Tissue Muscular tissue—elongated cells that are specialized to contract in response to stimulation Primary job is to ex...

CLICKER TIME……………… The approximate number of skeletal muscles in the body is a. 350 b. 500 c. 645 d. 715  Chapter 10 MUSCULAR SYSTEM Part One MUSCULAR TISSUE  Muscular Tissue Muscular tissue—elongated cells that are specialized to contract in response to stimulation Primary job is to exert physical force on other tissues and organs Creates movements involved in body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation Important source of body heat Three types of muscle: skeletal, cardiac, and smooth 5-6  Muscular Tissue Skeletal muscle ◦ Long, threadlike cells called muscle fibers Most attach to bone Exceptions: in tongue, upper esophagus, facial muscles, some sphincter muscles (ringlike or cufflike muscles that open and close body passages) Contains multiple nuclei adjacent to plasma membrane Striations—alternating dark and light bands Voluntary—conscious control over skeletal muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nuclei Striations Muscle fiber (a) (b) Figure 5.25a a: © Ed Reschke Figure 5.25b,i 5-7  Muscular Tissue Cardiac muscle ◦ Limited to the heart Myocytes or cardiocytes are shorter, branched, and notched at ends Contain one centrally located nucleus surrounded by light-staining glycogen Intercalated discs join cardiocytes end to end ◦ Provide electrical and mechanical connection Striated and involuntary (not under conscious control) Intercalated discs Striations Glycogen Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a) (b) Figure 5.26a © Ed Reschke Figure 5.26b,i 5-8 Clicker time…….. Intercalated discs are structures that keep cells of __________muscle together a. Cardiac b. Smooth c. Skeletal  Muscular Tissue Nuclei Muscle cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a) (b) Figure 5.27a a: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer Smooth muscle Figure 5.27b,i – Lacks striations and is involuntary Relatively short, fusiform cells (thick in middle, tapered at ends) One centrally located nucleus Visceral muscle—forms layers of digestive, respiratory, and urinary tract: propels contents through an organ, regulates diameter of blood vessels 5-10 Part Two MUSCULAR SYSTEM (SKELETAL MUSCLE)  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 ◦ Role in communication: speech, writing, nonverbal communications Stability ◦ Maintain posture by preventing unwanted movements ◦ Antigravity muscles: resist pull of gravity and prevent us from falling or slumping over ◦ Stabilize joints 10-12  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 ◦ What happens with weaker muscles? 10-13  Pause….. Functions of muscles? 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 10-15 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 10-16 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 Deltoid Biceps brachii Orbicularis oculi Figure 10.2 Strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles 10-17  Muscle Compartments Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior Lateral Medial Tibia Fibula Posterior Interosseous membrane Artery, veins, and nerve Intermuscular septa Fasciae Key Subcutaneous Anterior compartment fat Lateral compartment Posterior compartment, deep layer Figure 10.3 Posterior compartment, superficial layer 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 Pause……. Describe the arrangement of muscle fibers in a muscle fascicle.  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 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 10-20  Muscle Origins and Insertions Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Origin ◦ Bony attachment at stationary end of muscle Origins Origins Humerus Scapula Belly Bellies ◦ Thicker, middle region of Extensors: Flexors: muscle between origin and Triceps brachii Long head Biceps brachii Brachialis insertion Lateral head Insertion Insertion ◦ Bony attachment to mobile Insertion Radius Ulna end of muscle Figure 10.4 10-21 Biceps Brachii M. Functional Groups of Muscles Action—the effects produced by a muscle ◦ To produce or prevent movement ◦ The anatomy of kicking a soccer ball ◦ https://www.youtube.com/watch?v=NfRkYD_Rctg 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 10-23 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 ◦ Synergist muscle animation ◦ https://www.youtube.com/watch?v=4t2X2IvGyUE 10-24 Functional Groups of Muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Origins Origins Prime mover—brachialis Humerus Scapula Bellies Synergist—biceps brachii Extensors: Flexors: Triceps brachii Biceps brachii Long head Brachialis Lateral head Antagonist—triceps brachii Insertion Insertion Radius Ulna Fixator—muscle that holds scapula firmly in place Figure 10.4 ◦ Rhomboids 10-25 Pause…….What are the different functional groups of muscles? Give examples….. Intrinsic and Extrinsic Muscles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Intrinsic muscles— entirely contained within Common a region, such as the flexor tendon hand ◦ Both its origin and Flexor insertion there digitorum superficialis Flexor pollicis longus Extrinsic muscles—act on a designated region, Flexor digitorum but has its origin superficialis tendons elsewhere Flexor digitorum ◦ Fingers: extrinsic profundus tendons muscles in the forearm (b) Intermediate flexor Figure 10.28b 10-27  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 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 10-28 How Muscles Are Named Latin names ◦ Depressor labii inferioris – depresses the bottom lip ◦ flexor digiti minimi brevis – short muscle that flexes the smallest finger Describes distinctive aspects of the structure, location, or action of a muscle 10-29 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 10-30  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 10-31  The Muscular System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superficial Deep Deep Superficial Frontalis Orbicularis oculi Occipitalis Masseter Zygomaticus major Semispinalis capitis Orbicularis oris Sternocleidomastoid Sternocleidomastoid Splenius capitis Trapezius Platysma Trapezius Levator scapulae Pectoralis minor Supraspinatus Rhomboideus minor Deltoid Coracobrachialis Rhomboideus major Pectoralis major Infraspinatus Serratus anterior Deltoid (cut) Teres minor Brachialis Infraspinatus Teres major Biceps brachii Serratus anterior Rectus abdominis Triceps brachii Triceps brachii (cut) Supinator Serratus posterior inferior Latissimus dorsi Flexor digitorum Extensor carpi profundus External abdominal oblique Brachioradialis radialis longus Flexor pollicis longus Internal abdominal oblique and brevis Flexor carpi radialis External abdominal Transverse abdominal Erector spinae oblique External abdominal Internal abdominal Extensor digitorum oblique Flexor carpi ulnaris Gluteus medius Tensor oblique Pronator quadratus Extensor digitorum (cut) Extensor carpi ulnaris fasciae latae Gluteus minimus Gluteus maximus Lateral rotators Adductor Adductor longus magnus Sartorius Adductors Gracilis Rectus femoris Vastus lateralis Iliotibial band Semitendinosus Vastus lateralis Vastus intermedius Semimembranosus Iliotibial band Vastus medialis Gracilis Biceps femoris Biceps femoris Gastrocnemius (cut) Soleus (cut) Fibularis longus Gastrocnemius Gastrocnemius Tibialis posterior Flexor digitorum longus Tibialis anterior Soleus Soleus Extensor hallucis longus Extensor digitorum Fibularis longus Extensor digitorum longus longus Calcaneal tendon Figure 10.5a Figure 10.5b (b) Posterior view 10-32 (a) Anterior view