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5. SISTEM OTOT Powered By Docstoc
					Zuliyati Rohmah


Bahan Bacaan

Kardong, K.V., 2002, Vertebrates, Comparative Anatomy,
Function, Evolution, 3rd. ed., Mc. Graw Hill, Boston.


Weichert, C. K. 1970. Anatomy of The Chordates. Fourth
Edition. International Student Edition. McGraw-Hill Book

Company. Tokyo.

Kent, G.C. and R. K. Carr. 1997. Comparative Anatomy of the Vertebrate. Ninth Edition. The McGraw-Hill Companies. New York.


Mc Farland, W.N, Heiser, J.B, Pough, F.H. 1985. Vertebrate Life Second Edition. Macmillan Publishing Company. New York.

Sistem Otot (Overview...1)

Embryonic Derivation of Muscle (1)
Muscle is derived from embryonic mesoderm. The mesoderm is divided into:  Epimere (dorsal or paraxial mesoderm). The somites and somitomeres constitute most of the paraxial mesoderm. Somites have three regions: dermatome, myotome, and sclerotome. Dermatome forms the dermis of the middorsal skin, sclerotome gives rise to the vertebrae, and myotome forms appendicular and body wall muscles. In the head region, the paraxial mesoderm is not as segmented, and forms clusters of cells called somitomeres instead of somites. The

somitomeres give rise to cranial and pharyngeal muscles.


Sistem Otot (Overview...2)

Embryonic Derivation of Muscle (2)
  Mesomere. This gives rise to the kidney tubules and associated ducts. Hypomere (lateral plate mesoderm). The lateral-plate mesoderm is confined to the trunk and is divided into somatic mesoderm and
splanchnic mesoderm. Together, these give rise to blood vessels and the heart, connective tissue, peritoneum, dermis of body wall, the skeleton of the limbs and girdles, and smooth muscles. Until recently it was thought that the muscles of the gill arches was derived from splanchnic hypomere that extended forward into the gill arch region. However, recent studies using quail-chick chimaeras indicate that (at least in birds) the myoblasts that give

rise to branchiomeric muscles come from somites and somitomeres, which is epimere.


Sistem Otot (Overview...3)

Embryonic Derivation of Muscle (3)
Some smooth muscles arise from mesenchyme, which is mesodermal cells that are loosely organized in the embryo. But by far, most muscle is derived from the somites.





The Origin Of Muscle Tissue

The skeletal musculature arises from the paraxial mesoderm.

The intermediary mesoderm is involved in the formation of the urinary system. From the
unsegmented lateral plate mesoderm, the somato- and splanchnopleura form with the

coelom that lies in between them. Other mesoblast cells settle together
to form the cardiogenic and the myocardial plates. This is a connected group of cuboid cells in

the ventral mesoderm in front of
A. B.

Somite Somitocoel Neural tube

Paraxial mesoderm Intermediary mesoderm

the prechordal plate. From this ensemble of cells arises the cardiac

2. 3. 4.

C. Lateral plate mesoderm


Sistem Otot (Overview...4)

The textbook lists several ways of thinking about muscle tissue. One
general way is by microscopic appearance of the muscle cell; here types of muscle can be distinguished.

voluntary skeleton

involuntary heart

involuntary visceral organs



Sistem Otot (Overview...5)

Muscle can also be considered as somatic or visceral.
 Somatic muscles are derived from myotomes and include body

wall, tail, hypobranchial, tongue, extrinsic eye, branchiomeric, and most of the appendicular muscles.
 Visceral muscle comes from the splanchnic layer of the hypomere

(lateral plate), and includes erectors of feathers and hair, muscles of the gut, blood vessels, and viscera, and heart muscle.


Sistem Otot (Overview...6)

Muscles can also be described in terms of anatomical region.
 Appendicular muscles.—Note that the cartilage, bone, ligaments and

blood vessels of the limbs are formed from lateral plate mesoderm, which is hypomere. But most limb muscles are formed from myotome, which is part of the epimere.

Axial muscles.—The axial musculature forms from myotome, and becomes subdivided into epaxial and hypaxial muscle masses . do not confuse these with epimere and hypomere.
Cranial muscles.—The cranial muscles come from two very distinct sources.


The hypobranchial muscles are derived from myotomes of the somites and are supplied by the spinal nerves.


The branchiomeric muscles (those of the gill arches) are derived from somitomeres and supplied by cranial nerves.


Otot Skelet (Pengantar)


Skeletal (somatic or voluntary) muscles make up approximately 40% of the total human body weight. Their primary function is to produce movement through the
ability to contract and relax in a coordinated manner.


SKELETAL MUSCLE (skeletal muscle as organ)
Terdiri dari:
 Bagian muscular  t/d jaringan otot (muscle tissue) Skeletal

(striated) muscle is composed of elongate, multinucleated cells (muscle fibers)
 Jaringan ikat (muscle related connective tissue)Muscle fibers

are within a connective tissue framework that is continuous with tendons. As a result, passive muscles are able to serve as ties that reinforce joints & oppose forces on bones.



Muscle associated fascia: 1. epimysium = loose or dense connective tissue surrounding an entire muscle 2. perimysium = loose connective tissue defining muscle fascicles

endomysium = small amounts of loose c.t. surrounding individual muscle fibers

http://www.aspenatlas.com/photopost/showphoto.php?photo=530&si =Serous

http://phelafel.technion.ac.il/~tamarh/website/images/differnet-kinds-ofmuscles-1.jpg 16

Hubungan Otot Skelet dengan Tulang
 Hubungan secara langsungperimysium dan epimysium otot

bersatu dan fusi dengan periosteum tulang, perichodrium cartilago, atau jaringan ikat subkutis (misal otot mimik)
 Hubungan tidak langsung jaringan ikat otot menyatu membentuk

tendon. Tipe-tipe jaringan tendonius:
 Tendon  Muscle fascia, which is the connective tissue component of a muscle,
combine together and extend beyond the end of the muscle as round cords or flat bands, called tendons

 Aponeurosis  thin, flat and broad than tendon  Raphe  a seam of fibrous tissue, misal: linea alba


Tendon protection:  bursa = synovial pocket inserted between a tendon and a bony prominence  tendon synovial sheath = lubrication where tendons are bound, e.g., by retinaculum


There are three types of skeletal muscle fibres; red slow-twitch fibres, white fasttwitch fibres, and intermediate fast twitch fibres.
1. Red Slow-twitch Fibres (Type I) These are thin cells that contract slowly. The red colour is due to their content of myoglobin, a substance similar to haemoglobin, which stores oxygen and increases the rate of oxygen diffusion within the muscle fibre. As long as oxygen supply is plentiful, red fibres can contract for sustained periods, and are thus very resistant to fatigue. Successful marathon runners tend to have a high percentage of these red fibres.

2. Intermediate Fast-twitch Fibres (Type 2A)
These red or pink fibres are a compromise in size and activity between the red and white fibers.

3. White Fast-twitch Fibres (Type 2B) These are large cells that contract rapidly. They are pale, due to a lesser content of myoglobin. They fatigue quickly, because they rely on short-lived glycogen reserves in the fibre to contract. However, they are capable of generating much more powerful contractions than red fibres, enabling them to perform rapid, powerful movements for short periods. Successful sprinters have a higher proportion of these white fibres

Fascicle & fiber arrangement:
Parallel arrangement, e.g., strap or spindle arrangement, fibers/fascicles arranged parallel to the tendon of insertion. This results in a greater range of shortening and thus yields greater movement velocity (distance per time). Pennate arrangement = fibers/fascicles arranged at an angle to the direction in which the tendon moves. This results in a greater area of muscle fibers along axes of contraction and produces more strength (at the expense of a reduced range of contraction). Note: The amount of force that a muscle can generate is proportional to the area of muscle fibers, i.e., number of contractile protein molecules, multiplied by the cosine of the muscle-tendon angle. Three types of pennate arrangement are:
— unipennate, e.g., ulnar & radial heads of the deep digital flexor muscle; — bipennate, e.g., infraspinatus muscle;

— multipennate, e.g., humeral head of the deep digital flexor muscle.

How Muscle Work
A motor unit consists of a single motor nerve cell and the muscle fibres stimulated by it. The motor units vary in size, ranging from cylinders of muscle 5–7mm in diameter in the upper limb and 7–10mm in diameter in the lower limb. The average number of muscle fibres within a unit is 150 (but this number ranges from less than 10 to several hundred).
Skeletal muscles work on an ‘All or Nothing Principle’.

Skeletal muscle will not contract in the absence of a functional nerve supply (denervation atropy occurs). One neuron innervates a variable number of muscle fibers. The neuron plus the muscle fibers it innervates constitute a motor unit. To produce a stronger contraction, the nervous system activates more motor units.

Tata nama otot
Otot dapat dinamai berdasarkan:
 origo dan insersionya  misal sternohyoideus  Bentuk  deltoideus
 Lokasi  brachialis  Struktur  biceps  Fungsi  supinator  Atau kombinasi  pronator quadratus; superficial digital flexor;

serratus ventralis; flexor carpi radialis

Otot Apendikular


Appendicular Muscle
Otot yang terdapat pada gelang bahu/panggul, sirip, dan alat gerak. In fishes, the muscles of paired fins are simple; there is a dorsal extensor (levator) and ventral flexor (depressor). The mass of the fin muscles is only a small percentage of total body muscle. In tetrapods, the mass of the appendicular muscles is a much larger

part of total body muscle, and the musculature is far more complex. Appendicular muscles may be:
1) branchiomeric, 2) of axial (hypaxial) origin, or 3) from the limb bud proper,

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