Introduction to Muscles
Introduction to Muscles BIOL 240
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The Muscular System Part A 10 The Muscular System Part A 10 Hold onta big one.tes, this is 10 Interactions of Skeletal Muscles Skeletal muscles work together or in opposition Muscles only pull (never push) As muscles shorten, the insertion generally moves toward the origin Whatever a muscle (or group of muscles) does, another muscle (or group) “undoes” Muscle Classification: Functional Groups Prime movers – provide the major force for producing a specific movement Antagonists – oppose or reverse a particular movement Synergists Add force to a movement Reduce undesirable or unnecessary movement Fixators – synergists that immobilize a bone or muscle’s origin Naming Skeletal Muscles I call this one Betty Naming Skeletal Muscles Location of muscle – bone or body region Rectus associated with the Abdominus muscle Naming Skeletal Muscles Shape of muscle – e.g., the deltoid muscle (deltoid = triangle) Naming Skeletal Muscles Relative size – e.g., maximus (largest), minimus (smallest), longus (long) Gluteus Maximus Naming Skeletal Muscles Direction of fibers – e.g., rectus (fibers run straight), transversus, and oblique (fibers run at angles to an imaginary defined axis) Naming Skeletal Muscles Number of origins – e.g., biceps (two origins) and triceps (three origins) Triceps Brachii = Along, a lateral and Amedial origin Naming Skeletal Muscles ‘Cause this is the occiput Location of attachments – named according to point of origin or insertion Naming Skeletal Muscles Action – e.g., flexor or extensor, as in the names of muscles that flex or extend, respectively Major Skeletal Muscles: Anterior View Head Facial Temporalis Orbicularis oculial belly Masseter Zygomaticus The 40 superficial Shoulder Orbicularis oris Deltoidus Neck Arm Sternohyoid muscles here are Triceps brachii Sternocleidomastoid Biceps brachii Thorax divided into 11 Forearmalis Pectoralis minor Pronator teres Serratus anterior regional areas of Brachioradialis Pectoralis major Flexor carpi radialis Intercostals Palmaris longus Abdomen the body Pelvis/thigh Internal oblique Pectineus Transversus abdominis (definitely know Thigh External oblique Rectus femoris Thigh Vastus lateralis Tensor fasciae latae all of these + Vastus medialis Adductor longus Leg Gracilis thenar and Fibularis longus Leg Extensor digitorum longus Gastrocnemius hypothenar) Tibialis anterior Soleus Major Skeletal Muscles: Posterior View Neck The 26 superficial Epicranius, occipital belly Arm Sternocleidomastoid muscles here are Trapezius Triceps brachii Shoulder divided into 7 Brachialis Deltoid Forearm Infraspinatus Brachioradialis Teres major regional areas of Extensor carpi radialis longus Rhomboid major the body Flexor carpi ulnaris Latissimus dorsi Hip (definitely know ulnarisr carpi Gluteus medius Gluteus maximus all of these) Extensor digitorum Iliotibial tract Thigh Adductor magnus Hamstrings: Leg Biceps femoris Gastrocnemius Semitendinosus Soleus Semimembranosus Fibularis longus Calcaneal (Achilles) tendon Only 165 slides to go in this chapter covering almost every muscle in the body from the smallest eye muscle to the largest thigh muscle. If you haven’t started studying yet, tonight would be a very good time. Muscles: Name, O/I, Action, and Innervation Name and description of the muscle – be alert to information given in the name (ie, temporalis) Origin and insertion – there is always a joint between the origin and insertion Action – best learned by acting out a muscle’s movement on one’s own body (OK, everyone test the fibularis longus right now) Nerve supply – name of major nerve that innervates the muscle Muscles of the Scalp Here’s the first one. Let’s see if you can wrap your head around this one. Muscles of the Scalp Epicranius (occipitofrontalis) – bipartite muscle consisting of the: Frontalis & Occipitalis & Galea aponeurotica – cranial aponeurosis connecting above muscles These two muscles have alternate actions of pulling the scalp forward and backward Muscles of the Scalp Facial nerve Muscles of the Scalp Epicranius Galea aponeurotica Frontal belly Occipital belly Facial nerve Muscles of the Face 11 muscles are involved in lifting the eyebrows, flaring the nostrils, opening and closing the eyes and mouth, and smiling Japanese author Yasuhiro Kano All are innervated by cranial nerve VII (facial nerve) Usually insert in skin (rather than bone), and adjacent muscles often fuse Muscles of the Face Corrugator supercilii Orbicularis oculi Levator labii superioris minor and major Buccinator Risorius Orbicularis oris Mentalis Depressor labii inferioris Depressor anguli oris Platysma Yes, sorry, you just have to commit them to memory. Here’s a sample question from the test a) cranial nerve IIIl expression are innervated by… b) cranial nerve XII c) cranial nerve VII d) cranial nerve V Muscles of Mastication There are four pairs of muscles involved in mastication (chewing your food) Prime movers – temporalis and masseter Grinding movements – 2 pterygoids All are innervated by cranial nerve V (trigeminal nerve) Muscles of Mastication All four are Trigeminal nerve, CN V Temporalis Masseter Under masseter Muscles of Mastication pterygoid Medial pterygoid Masseter pulled away These are Trigeminal nerve, CN V Extrinsic Tongue Muscles Three major muscles that anchor and move the tongue All are innervated by cranial nerve XII (hypoglossal nerve) Extrinsic Tongue Muscles Cranial nerve XII (hypo-glossal nerve) For all the –glossus muscles Tongue Styloid process Styloglossus Genioglossus Hyoglossus Mandibular Stylohyoid symphysis Hyoid bone Geniohyoid Thyrohyoid Thyroid cartilage But, that’s it for the easy innervations: The next bunch have 7 different innervations Muscles of the Anterior Neck and Throat: Suprahyoid Four deep throat muscles Form the floor of the oral cavity Anchor the tongue Elevate the hyoid (suprahyoid, they only pull, so, these must elevate) Move the larynx superiorly during swallowing Muscles of the Anterior Neck and Throat: Suprahyoid Anterior Digastric belly Mylohyoid Posterior Stylohyoid belly Hyoid bone And, a geniohyoid which is deep to the mylohyoid Muscles of the Anterior Neck and Throat: Suprahyoid Mylohyoid Hyoid bone (cut) Geniohyoid But,,,,,,,, Muscles of the Anterior Neck and Throat: Infrahyoid Straplike muscles that depress the hyoid and larynx during swallowing and speaking Muscles of the Anterior Neck and Throat: Infrahyoid Omohyoid (superior belly) Thyrohyoid Sternohyoid Sternothyroid Omohyoid (inferior belly) But, again Then there’s this weird group that the book has listed under infrahyoid muscles but really is a group for swallowing and are found supra and infra to the hyoid ? Muscles of the Anterior Neck and Throat: Superior pharyngeal constrictor Middle pharyngeal constrictor Inferior pharyngeal constrictor Muscles of the Neck: Head Movements Muscles of the Neck: Head Movements Major head flexor is the sternocleidomastoid Lateral head movements are accomplished by the sternocleidomastoid and scalene muscles Head extension is accomplished by the deep splenius muscles and aided by the superficial trapezius Muscles of the Neck: Head Movements Base of 1st cervical occipital bone vertebra Mastoid process Middle Sternocleido- scalene mastoid Anterior scalene Posterior scalene (a) Anterior Muscles of the Neck: Head Movements Mastoid process Splenius capitis Spinous processes of the vertebrae Splenius cervicis (b) Posterior Muscles of the Neck: Head Movements Trapezius Muscles of the Neck: Head Movements Flexion and lateral flexion Muscles of the Neck: Head Movements Extension Get to the traps later. Trunk Movements: Deep Back Muscles Trunk Movements: Deep Back Muscles The prime mover of back extension is the erector spinae Erector spinae, or sacrospinalis, muscles consist of three columns on each side of the vertebrae – iliocostalis, longissimus, and spinalis Lateral bending of the back is accomplished by unilateral contraction of these muscles Other deep back extensors include the semispinalis muscles and the quadratus lumborum Trunk Movements: Deep Back Muscles Mastoid process of temporal bone Semispinalis Longissimus capitis capitis Iliocostalis cervicis Semispinalis Longissimus cervicis cervicis Iliocostalis Semispinalis thoracis thoracis Longissimus thoracis Spinalis thoracis Iliocostalis spinaer Longissimus Spinalis Multifidus Iliocostalis lumborum Quadratus lumborum External oblique (d) Trunk Movements: Deep Back Muscles Know this Not this Trunk Movements: Deep Back Muscles Nor this Trunk Movements: Short Muscles Four short muscles Nor this extend from one vertebra to another I = insertion These muscles are Intertransversarius synergists in extension and Rotatores Multifidus rotation of the Interspinales spine (e) Not in the table Muscles of Respiration - Ribs The only thing I could think of was the BBQ ribs and I already did that. Muscles of Respiration External The primary function intercostal of deep thoracic muscles is to promote movement for breathing External intercostals – more superficial layer that lifts the rib cage and increases thoracic volume to allow inspiration (a) Muscles of Respiration - Intercostals Internal intercostals – deeper layer that aids in forced expiration intercostal Muscles of Respiration - Intercostals Diaphragm – most important muscle in inspiration Muscles of Respiration: The Diaphragm Xiphoid process of sternum Foramen for inferior vena cava Foramen for esophagus Costal cartilage Central tendon of diaphragm Diaphragm Foramen for aorta vertebra 12th rib Quadratus lumborum Psoas major Muscles of Respiration: The Diaphragm Central tendon of diaphragm Body of thoracic vertebra Aorta Diaphragm (muscular part) Inferior vena cava Esophagus Pericardial sac Pericardium (cut) Muscles of Respiration: Table 10.5.1 Muscles of the Abdominal Wall Muscles of the Abdominal Wall Muscles of the Abdominal Wall The abdominal wall is composed of four paired muscles (internal and external obliques, transversus abdominis, and rectus abdominis), their fasciae, and their aponeuroses Fascicles of these muscles run at right and oblique angles to one another, giving the abdominal wall added strength Muscles of the Abdominal Wall - continue In addition to forming the abdominal wall, these muscles: Are involved with lateral flexion and rotation of the trunk Help promote urination, defecation, childbirth, vomiting, coughing, and screaming(sneezing, spitting, tackling, hitting a baseball, throwing, running, driving, getting out of bed, getting into bed………) Muscles of the Abdominal Wall Tendinous Transversus abdominis intersection Internal oblique Rectus abdominis External oblique Inguinal ligament external obliquehe (formed by free inferior border of the external oblique aponeurosis) (a) Muscles of the Abdominal Wall Linea alba Linea alba Not to be confused with……. Figure 10.11a Muscles of the Abdominal Wall JessicaAlba Muscles of the Abdominal Wall - continue Rectus abdominis Internal External oblique oblique Lumbar IIiac crest Pubic fascia tubercle Transversus Lumbar abdominis fascia Inguinal ligament (b) Muscles of the Abdominal Wall - continue Peritoneum Transversus abdominis Linea alba Rectus abdominis External oblique Internal oblique Aponeuroses Skin (c) Again, not…. Table 10.6.1 Muscles Inferior to the Pelvic Floor NC-17, please have your ID ready to show Muscles Inferior to the Pelvic Floor Two sphincter muscles allow voluntary control of urination (sphincter urethrae) and defecation (external anal sphincter) Muscles of the Pelvic Floor Urethral opening External urethral sphincter Vaginal Inferior pubic ramus opening Deep transverse perineal muscle Central tendon Anus External anal sphincter Male Female Muscles Inferior to the Pelvic Floor The ischiocavernosus and bulbospongiosus assist in erection of the penis and clitoris Muscles of the Pelvic Floor Urethral Clitoris opening Anus Vaginal Penis opening Midline raphe Ischiocavernosus Bulbospongiosus Superficial transverse perineal muscle Levator ani Gluteus maximus Male Female (c) Extrinsic Shoulder Muscles Extrinsic Shoulder Muscles Extrinsic Shoulder Muscles Muscles of the thorax Anterior: pectoralis major, pectoralis minor, serratus anterior, and subclavius Posterior: latissimus dorsi, trapezius muscles, levator scapulae, and rhomboids These muscles are involved with the movements of the scapula including elevation, depression, rotation, and lateral and medial movements Prime movers of shoulder elevation are the trapezius and levator scapulae Extrinsic Shoulder Muscles Subclavius Clavicle Subscapularis Deltoid Pectoralis minor Pectoralis major Coracobrachialis Sternum Serratus anterior Humerus Extrinsic Shoulder Muscles Muscles of the thorax Posterior: latissimus dorsi, trapezius muscles, levator scapulae, and rhomboids These muscles are involved with the movements of the scapula including elevation, depression, rotation, and lateral and medial movements Prime movers of shoulder elevation are the trapezius and levator scapulae Extrinsic Shoulder Muscles Levator scapulae Trapezius Supraspinatus Clavicle Deltoid Spine of scapula Rhomboid minor Infraspinatus Rhomboid Teres minor major Teres major Humerus Latissimus dorsi (c) Muscles Crossing the Shoulder Nine muscles cross the shoulder joint and insert into the humerus Prime movers include: Pectoralis major – arm flexion Latissimus dorsi and posterior fibers of the deltoid – arm extension Middle fibers of the deltoid – arm abduction Muscles Crossing the Shoulder Clavicle Deltoid Sternum Pectoralis major Latissimus dorsi (a) Anterior view (b) Posterior view Muscles Crossing the Shoulder Rotator cuff muscles – supraspinatus, infraspinatus, teres minor, and subscapularis SITS Function mainly to reinforce the capsule of the shoulder Secondarily act as synergists and fixators Muscles Crossing the Shoulder Supraspinatus Infraspinatus Teres minor Subscapularis Muscles Crossing the Shoulder The coracobrachialis and teres major: Act as synergists Do not contribute to reinforcement of the shoulder joint Muscles Crossing the Shoulder Clavicle Coracobrachialis Muscles Crossing the Shoulder Teres major Muscles Crossing the Elbow Muscles Crossing the Elbow Forearm extension The triceps brachii is the prime mover of forearm extension The anconeus is a weak synergist Muscles Crossing the Elbow Triceps brachii: Lateral head Long head Anconeus Muscles Crossing the Elbow Forearm flexion Brachialis and biceps brachii are the chief forearm flexors The brachioradialis acts as a synergist and helps stabilize the elbow Muscles Crossing the Shoulder Biceps Long head brachii Short head Biceps brachii Brachialis Brachioradialis Brachialis Muscles of the Forearm There are a lot of them. Yes, you have to know them. Muscles of the Forearm The two functional forearm muscle groups are: those that cause wrist movement, and those that move the fingers and the thumb These muscles insert via strong ligaments which pass under the flexor and extensor retinacula Most anterior muscles are flexors, and posterior muscles are extensors The pronator teres and pronator quadratus are not flexors, but pronate the forearm The supinator muscle is a synergist with the biceps brachii in supinating the forearm Muscles of the Forearm: Anterior Compartment These muscles are primarily flexors of the wrist and fingers Palmar aponeurosis Flexor retinaculum Pronator quadratus Flexor digitorum Flexor pollicis longus superficialis Flexor carpi ulnaris Palmaris longus Flexor carpi radialis Brachioradialis Medial epicondyle Pronator teres of humerus Muscles of the Forearm: Anterior Compartment These muscles are primarily flexors of the wrist and fingers Tendon of flexor digitorum superficialis Tendon of brachioradialis (cut) Tendon of flexor Pronator quadratus carpi ulnaris (cut) Tendon of flexor Flexor pollicis longus carpi radialis (cut) Flexor digitorum superficialis Flexor digitorum Extensor carpi profundus radialis longus Supinator Tendon of biceps brachii (cut) Table 10.11.1 There are some unspecified, as yet unidentified muscles Flexible Politicus Longus Flexible Politicus Longus Mudwater Quadratus Mudwater Quadratus Muscles of the Forearm: Posterior Compartment These muscles are primarily extensors of the wrist and fingers Extensor pollicis longus Extensor indicis Extensor pollicis brevis minimior digiti Abductor pollicis longus ulnarisr carpi Extensor digitorum Flexor carpi ulnaris Extensor carpi radialis brevis Extensor carpi radialis longus (a) Muscles of the Forearm: Posterior Compartment These muscles are primarily extensors of the wrist and fingers Interossei Extensor indicis Extensor pollicis brevis Extensor pollicis longus Abductor pollicis longus Supinator Anconeus Olecranon process of ulna More undiscovered muscles Extensor Carp Radials Longus and Brevis Not this one, but the… Extensor digitorum unos Not the supinator but the……. Intrinsic Muscles of the Hand Intrinsic Muscles of the Hand These small muscles: Lie in the palm of the hand (none on the dorsal side) Move the metacarpals and fingers Control precise movements (e.g., threading a needle) Are the main abductors and adductors of the fingers Produce opposition – move the thumb toward the little finger Intrinsic Muscles of the Hand Tendons of: Flexor digitorum profundus Fibrous sheath Flexor digitorum superficialis Second lumbrical Dorsal interossei Third lumbrical First lumbrical Fourth Adductor pollicis lumbrical Flexor pollicis brevis Opponens digiti minimi Abductor pollicis brevis Flexor digiti minimi brevis Opponens pollicis Abductor digiti minimi Flexor retinaculum Pisiform bone Abductor pollicis longus Flexor carpi ulnaris tendon Tendons of: Flexor digitorum Palmaris longus superficialis Flexor carpi radialis tendons Flexor pollicis longus (a) First superficial layer Intrinsic Muscles of the Hand Flexor digitorum profundus tendon Flexor digitorum superficialis tendon Dorsal interossei Palmar interossei Adductor pollicis Opponens digiti Flexor pollicis minimi brevis brevis (cut)i minimi Abductor pollicis Abductor digiti minimi brevis (cut) Opponens pollicis Flexor pollicis longus (b) Second layer tendon But……. Tendons of: Flexor digitorum profundus Fibrous sheath Flexor digitorum superficialis Second lumbrical Dorsal interossei Third lumbrical First lumbrical Fourth Adductor pollicis lumbrical Flexor pollicis brevis Opponens digiti minimi Abductor pollicis brevis Flexor digiti minimi brevis Opponens pollicis Abductor digiti minimi Flexor retinaculum Pisiform bone Abductor pollicis longus Flexor carpi ulnaris tendon Tendons of: Flexor digitorum Palmaris longus superficialis Flexor carpi radialis tendons Flexor pollicis longus (a) First superficial layer And…… Flexor digitorum profundus tendon Flexor digitorum superficialis tendon Dorsal interossei Palmar interossei Adductor pollicis Opponens digiti Flexor pollicis minimi brevis brevis (cut)i minimi Abductor pollicis Abductor digiti minimi brevis (cut) Opponens pollicis Flexor pollicis longus (b) Second layer tendon Except for these…….know these, for this class, can’t guarantee you won’t need to know the others later in life……… Flexor pollicis Opponens brevis digiti minimi Abductor pollicis Flexor digiti brevis minimi brevis Opponens pollicis Abductor digiti minimi Intrinsic Muscles of the Hand: Groups There are three groups of intrinsic hand muscles Thenar eminence (ball of the thumb) and Hypothenar eminence (ball of the little finger) – each have a flexor, an abductor, and an opponens muscle Midpalm muscles, the lumbricals and interossei, extend the fingers The interossei also abduct and adduct the fingers Lower Extremity Eadweard Muybridge Edward James Muggeridge April 9, 1830(1830-04-09) Born Kingston upon Thames, England May 8, 1904 (aged 74) Died Kingston upon Thames Resting place Woking Occupation Photographer Muscles Crossing Hip and Knee Joints Most anterior compartment muscles of the hip and thigh flex the femur at the hip and extend the leg at the knee Posterior compartment muscles of the hip and thigh extend the thigh and flex the leg The medial compartment muscles all adduct the thigh These three groups are enclosed by the fascia lata Fascia Lata not fascia latte Movements of the Thigh at the Hip: Flexion The most important thigh flexors are the iliopsoas (prime mover), tensor fasciae lata, and rectus femoris Movements of the Thigh at the Hip: Flexion Iliac crest Psoas major Iliopsoas Iliacus Anterior superior iliac spine Tensor fasciae latae • Rectus femoris Movements of the Thigh at the Hip: Flexion Movements of the Thigh at the Hip: Flexion The medially located adductor muscles and sartorius assist in thigh flexion If they assist that would make them?????? A) agonists B) synergists C) fixators D) protagonists E) assistorius Movements of the Thigh at the Hip: Flexion Psoas major Iliopsoas Iliacus Anterior superior iliac spine Tensor fasciae latae Pectineus Sartorius Adductor longus Adductor magnus • Rectus femoris Movements of the Thigh at the Hip: Flexion Adductor brevis Adductor magnus Adductor longus Femur Movements of the Thigh at the Hip: Flexion Movements of the Thigh at the Hip: Extension Thigh extension is primarily effected by the hamstring muscles (biceps femoris, semitendinosus, and semimembranosus) Forceful extension is aided by the gluteus maximus Movements of the Thigh at the Hip: Extension Gluteus maximus Long head Short headBiceps femoris Hamstrings Semitendinosus Semimembranosus Movements of the Thigh at the Hip: Extension Movements of the Thigh at the Hip: Extension Movements of the Thigh at the Hip: Medial Rotation ABduction and medial rotation are effected by the gluteus medius and gluteus minimus, and are antagonized by the lateral rotators Movements of the Thigh at the Hip: Medial Rotation Gluteus medius (cut) Gluteus minimus Movements of the Thigh at the Hip: Medial Rotation Movements of the Thigh at the Hip: Lateral Rotation Movements of the Thigh at the Hip: Medial Rotation Superior gemellus Piriformis Obturator Obturator internus externus Quadratus Inferior femoris gemellus Movements of the Thigh at the Hip: Lateral Rotation Movements of the Thigh at the Hip: Adduction Thigh adduction is the role of five adductor muscles (adductor magnus, adductor longus, adductor brevis, pectineus, and gracilis) Movements of the Thigh at the Hip: Adduction Pectineus (cut) Adductor Adductor brevis magnus Adductor longus Femur Movements of the Thigh at the Hip: Flexion Movements of the Knee Joint (a) Movements of the Knee Joint The sole extensor of the knee is the quadriceps femoris Vastus lateralis Vastus The hamstring intermedius muscles flex the Vastus Rectus femoris medialis tendon (cut) knee, and are Patella antagonists to the Patellar quadriceps femoris ligament Movements of the Knee Joint Muscles of the Leg: Movements Various leg muscles produce the following movements at the: Ankle – dorsiflexion and plantar flexion Intertarsal joints – inversion and eversion of the foot Toes – flexion and extension Muscles of the Anterior Compartment These muscles are the primary toe extensors and ankle dorsiflexors Tibia They include the Tibialis anterior tibialis anterior, Extensor digitorum longus extensor digitorum Extensor hallucis longus longus, extensor Fibularis tertius hallucis longus, and extensor retinaculaor fibularis tertius Muscles of the Anterior Compartment Tibialis anterior Extensor hallucis longus Extensor digitorum longus Muscles of the Anterior Compartment Muscles of the Lateral Compartment These muscles plantar flex and evert the foot They include the Fibularis longus fibularis longus and fibularis brevis muscles Fibularis brevis Muscles of the Lateral Compartment Fibularis longus Fibularis brevis Tendon of fibularis longus Muscles of the Lateral Compartment Muscles of the Posterior Compartment These muscles primarily flex the foot and the toes Gastrocnemius Medial head They include the Lateral head gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, and Tendon of gastrocnemius flexor hallucis longus Calcaneal tendon Medial malleolus Muscles of the Posterior Compartment Soleus Tibialis posterior Tendon of plantaris Fibula Flexor digitorum longus Flexor hallucis longus Muscles of the Posterior Compartment Tibialis posterior Flexor hallucis longus Flexor digitorum longus Muscles of the Posterior Compartment Muscles of the Posterior Compartment I know that you know that there is no need to know and no time to know everything there is to know, so, no need to know the intrinsic foot muscles. Muscles, end http://www.siumed.edu/~dking2/ssb/muscle.htm#1a http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__myofilament_contraction.html 9 9 Guess which subject now??? Muscles and Muscle Tissue PartA 9 Muscle Overview The three types of muscle tissue are skeletal cardiac smooth These types differ in structure, location, function, and means of activation Muscle Similarities Skeletal and smooth muscle cells are elongated and are called muscle fibers Muscle contraction depends on two kinds of myofilaments – actin and myosin Muscle terminology is similar Sarcolemma – muscle plasma membrane Sarcoplasm – cytoplasm of a muscle cell Prefixes – myo, mys, and sarco all refer to muscle Skeletal Muscle Tissue Packaged in skeletal muscles that attach to and cover the bony skeleton Has obvious stripes called striations Is controlled voluntarily (i.e., by conscious control) Contracts rapidly but tires easily Is responsible for overall body motility Is extremely adaptable and can exert forces ranging from a fraction of an ounce to over 70 pounds Cardiac Muscle Tissue Occurs only in the heart Is striated like skeletal muscle but is not voluntary Contracts at a fairly steady rate set by the heart’s pacemaker Neural controls allow the heart to respond to changes in bodily needs Smooth Muscle Tissue Found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages Forces food and other substances through internal body channels It is not striated and is involuntary Compare muscle tissue Skeletal Cardiac Smooth Striation: striated somewhat striated non-striated tapered cylinders Cells: straight cylindrical spindle shape parallel, non-branching parallel & branched Nucleus: multi-nuclei, mostly uni-nucleus uni-nucleus peripheral most peripheral central Discs: none intercalated none cardiac wall Location: attach bones hollow organs Control: voluntary involuntary involuntary Function: body movement heart contraction visceral & circulatory Speed of contraction: fastest intermediate slowest Skeletal Muscle Skeletal Muscle Each muscle is a discrete organ composed of muscle tissue, blood vessels, nerve fibers, and connective tissue Skeletal Muscle The three connective tissue sheaths are: Endomysium – fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiber Perimysium – fibrous connective tissue that surrounds groups of muscle fibers called fascicles Epimysium – an overcoat of dense regular connective tissue that surrounds the entire muscle Skeletal Muscle Bone Epimysium Tendon Blood vessel Fascicle (wrapped by perimysium) Endomysium (between individual muscle fibers) Muscle fiber Perimysium Fascicle Skeletal Muscle AKA Series Elastic Components Bone Epimysium Tendon Blood vessel Fascicle (wrapped by perimysium) Endomysium (between individual muscle fibers) Muscle fiber Perimysium Fascicle Skeletal Muscle Epimysium Perimysium Endomysium Muscle fiber in middle of a fascicle (b) Skeletal Muscle: Attachments Most skeletal muscles span joints and are attached to bone in at least two places When muscles contract the movable bone, the muscle’s insertion, moves toward the immovable bone, the muscle’s origin Skeletal Muscle: Attachments Muscles attach: Directly – epimysium of the muscle is fused to the periosteum of a bone ( more commonly) Indirectly – connective tissue wrappings extend beyond the muscle as a tendon or aponeurosis Microscopic Anatomy of a Skeletal Muscle Fiber Each fiber is a long, cylindrical cell with multiple nuclei just beneath the sarcolemma Fibers are 10 to 100 m in diameter, and up to hundreds of centimeters long Made by the fusion of hundreds of embryonic cells Contains myoglobin, O2 containing pigment similar to hemoglobin Fibers contain the usual organelles, plus myofibrils, sarcoplasmic reticulum, and T tubules Myofibrils Myofibrils are densely packed, rod-like contractile elements They make up most of the muscle volume The arrangement of myofibrils within a fiber is such that a perfectly aligned repeating series of dark A bands and light I bands is evident Nuclei Dark A band Light I band Fiber (a) Photomicrograph of portions of two isolated muscle fibers (700x). Notice the obvious striations (alternating dark and light bands). Myofibrils Sarcolemma Mitochondrion Myofibril DarkAband Light I band Nucleus DarkA(d-A-rk) Light I (l-I-ght) Sarcomeres - Z to Z The smallest contractile unit of a muscle The region of a myofibril between two successive Z discs Composed of myofilaments made up of contractile proteins Myofilaments are of two types – thick and thin Sarcomeres - Z to Z Thin (actin) “Helle” bright (helle is latin = bright) filament Z disc H zone Z disc Thick (myosin) I band I band A band M line filament It’s a thicker Sarcomere (c) word, too. ThickerA= thick filaments (+ some thin ones) Middle, centered Thinner I = all thin filaments between Z’sgure 9.3 (c) Myofilaments: Banding Pattern Thick filaments (myosin) – extend the entire length of an A band Thin filaments – extend across the I band and partway into the A band letter v. 5) and A is thicker than I (3 cm v. 1 cm)s v. 4), myosin is thicker than actin (6 Z-disc – coin-shaped sheet of proteins (connectins) that anchors the thin filaments and connects myofibrils to one another Myofilaments: Banding Pattern Thin filaments do not overlap thick filaments in the lighter (helle - bright) H zone M lines (middle, between Z lines) appear darker due to the presence of the protein desmin Myofilaments: Banding Pattern One Sarcomere Oooh, a third filament, recoils after contraction to pull it apart Myofilaments: Banding Pattern Contraction http://www.siumed.edu/~dking2/ssb/muscle.htm#1a Ultrastructure of Myofilaments: Thick Filaments Thick filaments are composed of the protein myosin Each myosin molecule has a rod-like tail and two globular heads Tails – two interwoven, heavy polypeptide chains Heads – two smaller, light polypeptide chains called cross bridges Ultrastructure of Myofilaments: Thick Filaments Thick filament Each thick filament consists of many myosin molecules whose heads protrude at opposite ends of the filament. Portion of a thick filament Myosin head About 300 myosin filaments Actin-binding sites binding Heads Tail site Flexible hinge region Myosin molecule Ultrastructure of Myofilaments: Thin Filaments Thin filaments are chiefly composed of the protein actin The subunits contain the active sites to which myosin heads attach during contraction Tropomyosin and troponin are regulatory subunits bound to actin (Regulatory subunits??? Is that like a Cop++riving a lowered Civic?), which are sensitive to Ca Ultrastructure of Myofilaments: Thin Filaments Thin filament twisted into a helix plus two types of regulatory proteins (troponin and tropomyosin). Portion of a thin filament Tropomyosin Troponin Actin Binds tropomyosin, actin and has Prevents myosin binding a third, open site for Ca++ Active sites for myosin Actin subunits attachment Actin subunits Arrangement of the Filaments in a Sarcomere Longitudinal section within one sarcomere Z Z Arrangement of the Filaments in a Sarcomere Thin filament (actin) Myosin heads Thick filament (myosin) Sarcoplasmic Reticulum (SR) SR is an elaborate, smooth endoplasmic reticulum 2+ Stores Ca Paired terminal cisternae form perpendicular cross channels T tubules associate with the paired terminal cisternae to form triads Sarcoplasmic Reticulum (SR) Part of a skeletal I band Aband I band muscle fiber (cell) Z disc H zone Z disc Myofibril M line Sarcolemma Triad: • T tubule • Terminal Sarcolemma cisternae of the SR (2) Tubules of the SR Myofibrils Mitochondria Sarcoplasmic Reticulum (SR) Sarcolemma Triad: T tubule • • Terminal cisternae of the SR (2) Tubules of the SR Myofibrils T Tubules T tubules conduct impulses to the deepest regions of the muscle These impulses signal for the release of Ca from adjacent terminal cisternae opening actin binding sites Open actin sites bind myosin allowing contraction Sliding Filament Model of Contraction Oops, I’ve slipped into physiology Thin filaments slide past the thick ones so that the actin and myosin filaments overlap to a greater degree In the relaxed state, thin and thick filaments overlap only slightly (titin pulls them back to neutral) Upon stimulation, myosin heads bind to actin and sliding begins Sequential Events of Contraction 1 Action potential is propagated along the sarcolemma and down Steps in the T tubules. E-C Coupling: Sarcolemma Voltage-sensitive T tubule tubule protein Ca2+ release channel 2 Calcium Terminal ions are cisterna released. of SR 2+ Ca Sequential Events of Contraction Actin Troponin Tropomyosin Ca2+ blocking active sites Myosin Calcium binds to 3 troponin and removes the blocking action of tropomyosin. Active sites exposed and ready for myosin binding 4 Contraction begins Myosin cross bridge The aftermath Thin filament 2+ Actin Ca Myosin ADP head P i Thick filament Myosin 1 Cross bridge formation. ADP ADP Pi ATP Pi hydrolysis 4 Cocking of myosin head. 2 The power (working) stroke. ATP ATP 3 Cross bridge detachment. Sliding Filament Model of Contraction http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__myofilament_contraction.html Actin and myosin Muscle Fiber Type: Functional Characteristics Speed of contraction – determined by speed in which ATPases split ATP The two types of fibers are slow and fast ATP-forming pathways Oxidative fibers – use aerobic pathways Glycolytic fibers – use anaerobic glycolysis These two criteria define three categories – slow oxidative fibers, fast oxidative fibers, and fast glycolytic fibers Muscle Fiber Type: Speed of Contraction Slow oxidative fibers contract slowly, have slow acting myosin ATPases, and are fatigue resistant Fast oxidative fibers contract quickly, have fast myosin ATPases, and have moderate resistance to fatigue Fast glycolytic fibers contract quickly, have fast myosin ATPases, and are easily fatigued Robert Cheruiyot Boston finishing time of 2:07:14 Red/slow Red/slow Paula Radcliffe Lenda Murray, 2004 New York Marathon 8 X Miss Olympia in a time of 2 hours 23 minutes 10 White/fast seconds Cross section of the three types of fibers in skeletal muscle. FO SO FG Smooth Muscle Composed of spindle-shaped fibers with a diameter of 2-10 m and lengths of several hundred m Lack the coarse connective tissue sheaths of skeletal muscle, but have fine endomysium Organized into two layers (longitudinal and circular) of closely apposed fibers Found in walls of hollow organs (except the heart) Have essentially the same contractile mechanisms as skeletal muscle Smooth Muscle Longitudinal layer of smooth muscle (shows smooth muscle fibers in cross section) Small intestine Mucosa (a) (b) Cross section of the Circular layer of intestine showing the smooth muscle smooth muscle layers (shows longitudinal (one circular and the views of smooth other longitudinal) muscle fibers) running at right angles to each other. Microscopic Anatomy of Smooth Muscle SR is less developed than in skeletal muscle and lacks a specific pattern T tubules are absent Plasma membranes have pouchlike infoldings called caveoli Ca is sequestered in the extracellular space near the caveoli, allowing rapid influx when channels are opened There are no visible striations and no sarcomeres Thin and thick filaments are present Proportion and Organization of Myofilaments in Smooth Muscle Intermediate Caveolae Gap junctions filament Like Z lines Nucleus Dense bodies (a) Relaxed smooth muscle fiber (note that adjacent fibers are connected by gap junctions) Nucleus Dense bodies (b) Contracted smooth muscle fiber Contraction of Smooth Muscle Whole sheets of smooth muscle exhibit slow, synchronized contraction They contract in unison, reflecting their electrical coupling with gap junctions Developmental Aspects: Male and Female Developmental Aspects: Male and Female There is a biological basis for greater strength in men than in women Women’s skeletal muscle makes up 36% of their body mass Men’s skeletal muscle makes up 42% of their body mass Developmental Aspects: Male and Female These differences are due primarily to the male sex hormone testosterone With more muscle mass, men are generally stronger than women Body strength per unit muscle mass, however, is the same in both sexes Developmental Aspects: Age Related Developmental Aspects: Age Related With age, connective tissue increases and muscle fibers decrease Muscles become stringier and more sinewy By age 80, 50% of muscle mass is lost (sarcopenia) Developmental Aspects: Age Related Regular exercise reverses sarcopenia End Guess what’s next Joints Articulations Part8A But, first……. After the first exam, some may do very well. Those who do are not to be harassed, threatened, groaned at, keyed, etc. They worked hard, did well and deserve the grade. They are to be congratulated, adulated and considered as gods among the mortals. Joints (Articulations) Weakest parts of the skeleton Articulation – site where two or more bones meet Functions of joints Give the skeleton mobility Hold the skeleton together Classification of Joints: Structural Structural classification focuses on the material binding bones together and whether or not a joint cavity is present The three structural classifications are: Fibrous Skull Cartilaginous Synovial Classification of Joints: Functional Functional classification is based on the amount of movement allowed by the joint The three functional classes of joints are: Synarthroses – immovable Skull (Syn= together, arthro = joint) Amphiarthroses – slightly movable Diarthroses – freely movable (Dia = apart, arthro = joint) Classification of Joints: Functional Functional classification is based on the amount of movement allowed by the joint The three functional classes of joints are: ? – immovable Skull (Syn= together, art
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