General Myology

General myology

• generation of movements • stabilization of the position of the body • control of the volume of the organs – smooth muscle - sphincters • motion of the substances in the body – blood, lymph, urine, air, food and fluids, sperm • generation of body heat – voluntary and involuntary contractions of skeletal striated muscle © David Kachlík 30.9.2015 Characteristics of the muscle tissue

• electrical irritability (excitability) – ability of the skeletal muscle to respond to stimuli – skeletal muscle contracts as a result of nerve irritation • contractility – ability of contraction • extensibility – ability to extend without tissue damage • elasticity – ability to return to the original shape after being extended

• smooth muscle tissue (textus muscularis levis) • striated muscle tissue (textus muscularis striatus) • cardiac striated mucle tissue (textus muscularis striatus cardiacus)

• smooth muscle cell (myocytus levis) • nucleus is in the centre of the cell • in sarcoplasm there are longitudinally placed contractable myofibrils made of myofilaments (myofilamenta) – myofilamentum crassum – myofilamentum tenue • even at rest it is in a mild contractile state – tonus • doesn´t become fatigued • inervated by automonic system is not under voluntary control © David Kachlík 30.9.2015 Smooth muscle

© David Kachlík 30.9.2015 Eis, Jelínek, Špaček, Histopatologický atlas, Praha 2006 Skeletal striated muscle I myofibre (myofibra) • elementary structural unit • multinucleated • thickness: 10–100 µm • length: mm – cm • origin: merging of elongated mononuclear cells (myoblasts) → myotubes (nuclei inside, myofibrils at the surface) → conversion to myofibres (nuclei at the surface, myofibrils inside) • sarcolemma on the surface – striated in the microscope © David Kachlík 30.9.2015 • lighter and darker sections Skeletal striated muscle II

• myoglobin (pigment causing red colouring) • fibres – quick • quickly fatigued • light (white) • in superficial layers – slow • more resistant to tiredness • dark (red) • in deeper layer • inervated by cranial and spinal nerves – without inervation non-functional and atrophies © David Kachlík 30.9.2015 Myofilaments and sarcomeres

• thick (myosin) and thin (actin) myofilaments (myofilamenta) overlap so they create annealing • sarcomere (sarcomerum) – contractile muscle units of skeletal and cardiac muscle – reach from one Z-disc to another

© David Kachlík 30.9.2015 © David Kachlík 30.9.2015 http://www.baileybio.com/plogger/?level=picture&id=264 http://www.bms.ed.ac.uk/research/others/smaciver/Myosin%20II.htm Skeletal striated muscle – longitudinal section

• microscopically looks like a net • similar to skeletal muscle tissue • fibres connected by diagonal plasmatic bridges • intercalated disc (discus intercalaris) – divides cardiac muscle tissue into mononuclear segments (cells) • nucleus in the middle of the cell • sarcolemma on the surface • conducting system of the heart (complexus stimulans cordis) – modified cells of the cardiac muscle are specialized to generate impulses and to conduct© David Kachlíkthem 30.9.2015 Cardiac muscle tissue

intercalated disc

• striated muscle fibres • special muscle structures • primary muscle bundle – 10-100 fibres connected and covered by fibrous tissue • secondary bundles – connection of primary bundles and covering by fibrous tissue

• bundles of higher© David orders Kachlík 30.9.2015 Basic muscle structure II

• fibrous tissue – endomysium (perimysium internum) • covers myofibres and bundles – epimysium (perimysium externum) = fascia • covers the whole muscle • tendon (tendo) • aponeurosis (aponeurosis) • myotendinous junction (junctio myotendinea) – connection of myofibres with first (originating) and inserting tendon

• origin (origo) – mobile end (punctum fixum) • head (caput musculi) origin belly • belly (venter musculi)

• attachment (insertio) insertion – fixed point (punctum mobile)

http://medicina.ronnie.cz/c-1349-Makroskopicka-stavba-svalu.html

© David Kachlík 30.9.2015 External muscle shape • fusiform muscle (m. fusiformis) • two-headed muscle (m. biceps) • three-headed muscle (m. triceps) • four-headed muscle (m. quadriceps) • flat muscle (m. planus) • two-bellied muscle (m. biventer) • orbicular muscle (m. orbicularis) • pennate muscle (m. pennatus) – semipennate muscle (m. semipennatus) – multipennate muscle (m. multipennatus)

– diagonally directed ©bundles David Kachlík face 30.9.2015 towards the inserting tendon © David Kachlík 30.9.2015

Čihák R., Anatomie 1, Grada Publishing a.s. 2001 Muscle contraction

• velocity: in tens of miliseconds • contraction – isotonic • length changed, inner tonus unchanged • concentric (shortening of a muscle) • excentric (lengthening of a muscle) – isometric • length unchanged, muscle belly tonus changed

• spasm – involuntary contraction of one muscle • cramp – painful spasm • tetanus – multiple spasms of skeletal muscles • tic – involuntary twiches of muscles, usually under voluntary control • tremor – rhythmical, involuntary contractions of opposite groups of muscles • fasciculations – involuntary, short twiches on motor unit visible under the skin • fibrilace – spontaneous contractions of fibres of one muscle that aren´t visible under the skin © David Kachlík 30.9.2015 Function of a muscle I

• agonists – in the same direction acting muscles • antagonists – counteracting muscles • synergists – muscles participating in one movement (working together) • main (principal) muscle – one out of the group of synergists • auxiliary (accesory) muscles

– they act together with© David the Kachlík principal 30.9.2015 muscle Function of a muscle II

• fixative (stabilizing) muscles – firm up the part of the body, that causes the movement • neutralizing muscles – neutralize unwanted directions of movements • one-jointed muscles – they´re causing the movement only in 1 joint • double-jointed (multiple-jointed) muscles – they act mainly in the joint closest to the insertion © David Kachlík 30.9.2015 Function of a muscle III

• flexor (m. flexor) • levator (m. levator) – makes the angle in the joint – lifts up a part of the body more acute • depressor (m. depressor) • extensor (m. extensor) – drops down a part of the body – makes the angle in the joint • pronator (m. pronator) more obtuse – helps with pronation • adductor (m. adductor) • supinator (m. supinator) – moves the bone medially – helps with supination • abductor (m. abductor) • opponens (m. opponens) – moves the bone laterally – places the thumb against other • rotator (m. rotator) fingers – turns the bone around its long • sphincter (m. sphincter) axis © David Kachlík• 30.9.2015dilator (m. dilatator) Function of a muscle IV

• tonus – maintains the permanent tension of the muscle – maintains the correct position of the joints and parts of the body – decreases in sleep and narcosis • postural muscles – ensure upright posture of the body

• neurovascular hilus – point of entry for nerves and vessels into the muscle • diploneural muscles – inervated by 2 peripheral nerves • plurineural muscles – inervated by more nerves • neural fibres – motor – sensory – autonomic (visceromotor)

http://www.sciencedirect.com/science/article/pii/S1748681505004535 © David Kachlík 30.9.2015 Motor inervation

• somatomotor fibres are axons of motoneurons of anterior spinal horns (α-motoneurons) • neuromuscular synapse (synapsis neuromuscularis) – termination of an axon on the surface of myofibre • motor unit – group of myofibres inervated by 1 motoneuron – simple, rough movements – big motor unit (150 myofibres) – delicate, precise movements – small motor unit (8–15 myofibres)

Richard S. Snell, Clinical Anatomy, Lippincott Wiliams & Wilkins 2004 Gray´s anatomy, 35th British edition, W.B.Saunders Company Philadelphia 1973 Muscle spindle Fusus neuromuscularis

= intrafusal muscle fibres • specialized organ of perception in the muscle = proprioception • consists of several myofibres • surrounded by fibrous capsule • inervated by fibres of γ-motoneurons – informations about length change to the spinal cord • detects also difference of grade of contraction of extra– and intrafusal fibres

doc. MUDr. Josef Zámečník,© David Ústav patologie Kachlík a molekulární 30.9.2015 medicíny 2.LF UK a FN v Motole Muscle spindle – transverse section

doc. MUDr. Josef Zámečník,© David Ústav patologie Kachlík a molekulární 30.9.2015 medicíny 2.LF UK a FN v Motole Fig. 14-4. Neuromuscular spindle. Cross section. Equatorial region. Triceps surae muscle. Rat embryo, 2 days before birth. E.M. x1200. (From: J.H. Levy, 1972) 1. Extrafusal skeletal muscle fibers. 2. Lumen of blood capillary. 3. Outer capsule. 4. Periaxial space. 5. Inner capsule. 6. Myelinated nerve fibers. 7. Intrafusal nuclear chain muscle fibers. 8. Nuclear bag muscle fibers. 9. Fibroblasts. 10. Loose connective tissue.

Fig. 14-5. Neuromuscular spindle. Cross section. Juxta-equatorial region. Front leg muscle. Newborn rat. E.M. x1900. 1. Extrafusal skeletal muscle fibers. 2. Lumen of capillary. 3. Outer capsule. 4. Periaxial space. 5. Inner capsule. 6. Myelinated nerve fibers. 7. Nuclear chain muscle. 8. Nuclear bag muscle fibers.

J.A.G. Rhodin: Histology. A text and atlas. 1974 Fig. 14-6. Neuromuscular spindle. Cross section. Juxta-equatorial region. Enlargement of rectangle in Fig. 14-5. E.M. x4500. 1. Part of extrafusal muscle fiber. 2. Lumen of capillary. 3. Sheet-like cells of outer capsule. 4. Myelinated nerve fibers. 5. Periaxial space. 6. Inner capsule. 7. Nucleus of fibroblast. 8. Nucleus of Schwann cell. 9. Nucleus of nuclear bag fiber. 10. Polar ends of nuclear chain fibers. 11. Satellite muscle cell. 12. Sensory nerve endings.

Fig. 14-7. Sensory nerve ending. Neuromuscular spindle. Enlargement of rectangle in Fig. 14-6. E.M. x60,000. 1. Myofilaments of intrafusal nuclear chain muscle fiber. 2. Sensory nerve ending. 3. Mitochondria. 4. Membranous contact between sarcolemma and cell membrane of nerve ending. 5. Zonula adherens junction. 6. External (basal) lamina.

J.A.G. Rhodin: Histology. A text and atlas. 1974 Fig. 14-18. Motor nerve endings. Skeletal muscle. Gold chloride method. Human. L.M. x200. 1. Striated muscle fibers. 2. Bundle of myelinated nerve fibers. 3. Motor end plates.

Fig. 14-19. Motor end plates. Gold chloride method. Skeletal muscle. Human. L.M. x600. 1. Efferent nerve fibers. 2. Motor end plate in surface view. 3. Motor end plate in side view. 4. Striated skeletal muscle fibers.

Fig. 14-20. Motor end plate. Skeletal muscle. Enlargement of area approximately similar to rectangle in Fig. 14-19. Rat. E.M. x30,000. 1. Efferent nerve process (axon). 2. Myelin sheath. 3. Successive laminae of the myelin sheath terminate as cytoplasmic swellings. 4. Cytoplasm of Schwann cell (neurolemma). 5. Endoneurial connective tissue. 6. Cytoplasm of teloglial cell (Schwann cell). 7. Axon terminal end (end knob). 8. Synaptic trough (recess). 9. Mitochondria. 10. Subneural, synaptic clefts. 11. Nucleus of skeletal muscle cell. 12. Myofibrills. 13. External (basal) lamina.

J.A.G. Rhodin: Histology. A text and atlas. 1974 Fig. 14-21. Detail of motor end plate. Skeletal muscle. Rat. E.M. x60,000. 1. Axon terminal. 2. Cytoplasm of muscle cell (sole plate). 3. Mitochondria. 4. Flat synaptic vesicles. 5. Round synaptic vesicles. 6. Presynaptic membrane. 7. Synaptic cleft with glycoprotein material. 8. Postsynaptic, junctional folds. 9. Subneural primary and secondary clefts. 10. Postsynaptic sarcolemma. 11. Synaptic vesicles fusing with presynaptic membrane. 12. Microtubules. 13. Ribosomes.

Figs. 14-22. and 14-23. Detail of synaptic junctions of motor end plate. Skeletal muscle. Rat. E.M. x124,000. 1. Presynaptic cell membrane of axon terminal. 2. Synaptic cleft. 3. Postsynaptic sarcolemma. 4. Round (excitatory?) electron-lucent, synaptic vesicles, bounded by a delicate, trilaminar membrane. 5. Flat (inhibitory?) synaptic vesicles.

J.A.G. Rhodin: Histology. A text and atlas. 1974 Vascular supply of a muscle

• entry and exit of the vessels in muscle neurovascular hilus • flowing blood volume depends on the activity of the muscle • poor supply for the tendons – blood and lymph vessels of their own – branches of the vessels for the muscle, periosteum, tendons

• lengthwise growth – growth of length of myofibres at their ends • widthwise growth – myofibres are getting thicker • from birth the amount of myofibres is unchanged • cells are not regularly renewed regeneration practically can´t occur © David Kachlík 30.9.2015 Special muscle structures I

• fascia (= perimysium externum) – fibrous envelope of muscle or muscle group – barrier for spreading of inflammation in that specific area

• osteofascial septum (= septum osteofasciale) – fascial divider from the superficial fascia to the periosteum – separates the space for muscle groups – compartment (compartimentum)

• in the first hours after injury of the muscle or fractures of the long bones of the thigh, leg, arm or forearm • increase of pressure in the fascial space (intramuscular bleeding, oedema) → compression of the vessels → ischemia with possible necrosis • treatment is mostly surgical – fasciotomy or dermatofasciotomy – fascial incision (together with skin) for decreasing the pressure in the fascial space • Volkmann´s contracture – flectional contracture of the hand and fingers as a result of postischemic fibrous degeneration of muscle bellies of the flexors, sometimes also extensors

© David Kachlík 30.9.2015 http://lifeinthefastlane.com/ortho-library/compartment-syndrome/ Special muscle structures II • tendon (tendo) – strip of tough fibrous connective tissue composed of bundles of collagenous fibrils – connects the muscle to the bone – peritenonium internum (covers the bundles) – peritenonium externum (consistent envelope on the surface of the tendon) • aponeurosis (aponeurosis) – flat tendon – mutually crossing bundles in layers • tendinous sheath (vagina tendinum) – space along the tendon lined by synovial membrane – vagina fibrosa: surrounds the vagina synovialis, holds the tendons to the bone – vagina synovialis • epitenonium: inner layer (covers the tendon) • peritenonium: outer layer • mesotenonium: mutual switching of both previous things © David Kachlík 30.9.2015

http://www.zoology.ubc.ca/~biomania/tutorial/bonejt/jt01ac03.htm Special muscle structures III • bursae mucosae – pouches in the vincinity of the joints, tendons and muscles – lined by synovial membrane, filled up with synovial fluid – reduction of rubbing in places exposed to considerable movement and pressure • retinacula – strengthened stripes of the superficial fascia – tie the inserting tendons to the bone – together with the skeleton create osteofibrous canal • vincula – mesotenonium of tendinous sheaths of the flexors of the hand – vascular supply for corresponding tendons run through them – vincula brevia et longa© David Kachlík 30.9.2015 http://medical-dictionary.thefreedictionary.com/bursa http://www.blackburnfeet.org.uk/hyperbook/trauma/ankleFx/ankleFxBasic1.htm http://www.msdlatinamerica.com/ebooks/SurgicalExposuresinOrthopaedicsTheAnatomicApproach/sid139333.html Development – muscles of the trunk

• from dermatomyotoms (part of the somites) – epaxial unit • maintains the segmental arrangement • inervation: posterior rami of the spinal nerves • deep muscles of the back – hypaxial unit • merges into larger units • inervation: anterior rami of the spinal nerves • lateral and anterior muscles of the body wall – border: fascia thoracolumbalis – lamina media

http://www.sharksinfo.com/lateral-line.html

http://en.wikipedia.org/wiki/Epaxial_and_hypaxial_muscles

• migration of hypaxial myogenic cells from ventrolateral margin of the dermatomyotom to the limb bud • secondary extension of the beginnings to the trunk – spinohumeral muscles – thoracohumeral muscles • inervation: anterior rami of the spinal nerves – form the plexuses

• plexus brachialis (brachial plexus) – C5-8, T1

• plexus lumbalis (lumbar plexus) – T12, L1-4

• detection of the superficial muscle or the intramuscular activity • detects the change of electrical potential • diagnostics for various muscle and neural malfunctions

http://biomech.ftvs.cuni.cz/pbpk/kompendium/biomechanika/experiment_metody_emg.php

• informs us about the muscle strength • helps to assess the extent and location of the impairment • analysis and examination of performance for the whole movement • assessment – 6 grades • 0 – no sign of contraction • 1 – twich (not enough to do the move) • 2 – very weak (movement in the whole extent, doesn´t overcome the resistance of the tested part of the body) • 3 – weak (overcomes the gravity) • 4 – good (overcomes medium-sized outer resistance) • 5 – normal (very good function) © David Kachlík 30.9.2015 Rigor mortis

• is state of muscle rigidity, that begins 3-4 hours after death and lasts approx. 24 hours • after death Ca2+ ions leave the sarcoplasmatic reticulum and enable the myosin heads to bond to the actin fibres • since the synthesis of ATP has ceased, actin bridges don´t separate until the time when proteolytic enzymes start to eliminate the cells

• skeletal muscle tissue starts to be replaced by fibrous and fatty tissue around the age of 30 • reflexes slowdown, loss of flexibility and decrease of strength • change of muscle fibres from quick to slow

• illness of muscle and tendinous insertions • usually caused by repeated overstraining • e.g. tennis elbow

http://www.fyzioterapie-stepankavojtova.cz/bolestivyloket.html © David Kachlík 30.9.2015http://compex.zdravi-cz.eu/tenisovy-loket.php