Анатомия домашних животных миология = Anatomy of domestic animals Myology. Учебно-методическое пособие

Other types of muscles (dynamo-static, semistato-dynamic and statodynamic) consist of decreased ratio of striated muscle and elements of connective tissue.

Stato-dinamic muscles commonly have pennate structure and can be uni-, biand multipinnae. Dynamic muscles are characterized by straight direction of muscular bundles.

1.Flexor brings together ends of bones during contraction.

2.Extensor goes through angular point of joint and opens it during contraction.

3.Abductor lies on lateral surface of joint and sets it aside from sagittal plane.

4.Adductor lies on medial surface of joint and by contraction leads to sagittal plane.

5.Rotator provides rotation of limb outside (supinator) or inside (pronator).

6.Sphincters are located around natural openings and close them during contraction. Generally, they are characterized by circulatory direction of muscle bundles (e.g. orbicular muscle of mouth).

7.Constrictors are also referring to circulatory type of muscles, but they have another form (e.g. constrictors of larynx and pharynx).

8.Dilatator open natural opening during contractions.

9.Tensor string up fasciae, not allowing it to wrinkle.

10.Fixators strengthen joint on the side of corresponding muscles.

V. By relation to joint muscles site differently, according to its structure and function. Some connect adjacent bones and effect only one joint – monarthric; other muscles go through 2 or more joints – diarthric and multiarthric. Later are usually longer and lies externally.

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VI. By disposition muscles can be superficial and profound, external and internal, lateral and medial.

VII. By origin all skeletal muscles are divided into somatic and visceral. Somatic muscles develop from dorsal part of mesoderm, and visceral – from ventral. Visceral musculature comprises muscles of head (mimic, masseteric) and some cervical, muscles.

Moreover, it’s important to mention, that muscles act separately or in groups. Similarly functioning muscles are called synergists, and contrary functioning muscles are called antagonists.

1.3Accessory apparatus of muscles

Contracting muscles provide their function involving and being assessed by anatomical structures, that should be mentioned as accessory muscular apparatus. It comprises fasciae, bursae, synovial sheath of tendons, trochleae and sesamoid bones.

Table 4

Accessory muscular apparatus

1.3.1 Fascia

Fascia (fascia – cover) is a thin, transparent, connective tissue cover, that forms around muscles peculiar coat. They mainly provide supportive and shock-absorbing functions. Fasciae separate muscles from each other, provide support to myogaster during its contraction and eliminate rubbing of adjacent muscles. Fasciae are called a “soft skeleton” (it is believed to be remains of membranous skeleton of vertebrates’ ancestors). They are rich

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with nerves (receptors) and vessels, so they play sustainable role in recovery processes (regeneration). For instance, if after removal of affected meniscus from knee joint we place innervated and vascularized part of fascia on its place, then in a while with appropriate training this part of fascia reforms in an “organ” resemblingmeniscus,andthejointfunctionrecovers.Thus,fasciae are broadly used in reconstructive surgery during autoplastic surgery of cartilaginous and bone tissues. Fasciae can be superficial, profound and special.

Superficial or subcutaneous fasciae separates skin from skeletal muscles and form peculiar coats for all regions of animals’ body. Cutaneous muscles are connected to it.

1)Superficial head muscle (f. superficialis capitis) covers head muscles.

2)Cervical fascia (f. cervicalis) lies ventrally in neck area and covers trachea.

3)Thoracolumbar fascia (f. thoracolumbalis) lies dorsally on the trunk and connects to spinal processes of thoracic and lumbar vertebrates and the head of the femur.

4)Thoracoabdominal fascia (f. thoracoabdominalis) lies laterally from both sides of thoracic and abdominal cavities and bonds ventrally on the white abdominal line (linea alba).

5)Superficial fascia of forelimb (f. superfacialis membri thoracici) is a continuation of thoracoabdominal fascia. It is considerably thicker in carpus area and forms fibrous sheaths for muscles’ tendons of this area.

6)Superficial fascia of hindlimb (f. superfacialis membri pelvini) is a continuation of thoracolumbar fascia and is considerably thicker in tarsus area.

Profound or individual fasciae connect to bones and hold muscles in definite position without drifting. They form coats for separate muscles, group muscles (synergists) and organs.

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1)In head area, superficial fascia divides into several profound: frontal (covers nasal dorsum), temporal, parotidmasseteric, buccal, submaxillary, buccopharyngeal.

2)Intrathoracic fascia (f. endothoracica) covers internal surface of thoracic cavity.

3)Transverse abdominal fascia (f. transversalis) covers internal surface of abdominal cavity.

4)Pelvic fascia (f. pelvicis) covers internal surface of pelvic

cavity.

5)In forelimb superficial fascia divides into several profound: fasciae of scapula, brachium, antebrachium, hand and digits.

6)In hindlimb superficial fascia divides into several profound: fasciae of femur, tibia, pes and digits.

Special fasciae cover individual muscles. For instance, profound parotid-masseteric fascia divides into two special: parotid covers salivary gland, and masseteric covers masseter.

1.3.2 Bursa

Bursa (lat. Bursa – bag) is situated at the places of attachments and maximum mobility of tendons and muscles. It is a flat bag of connective tissue, its internal layer is lined up by mesotheliumexcretingfluid,thusthere’salwaysfluidinsidebursa. Bursa decreases rubbing and smooths junction of muscles and other organs (bones, skin). They have varied sizes: from several millimeters to several centimeters.

Near joint cavity of bursa is always intercommunicates with cavity of joint capsule. These bursae are commonly situated near elbow and knee joints. Inflammation of these bursae after trauma can lead to arthritis (inflammation of joint) of elbow and knee joints, it is that you should remember in veterinarian practice.

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Bursa is a supportive structure and lies under other anatomical structures and sites in most fragile areas: under ligaments (subligamentous), under muscles (submuscular), under tendons (subtendinous), under skin (subcutaneous).

Bursae can be constant or temporal (heloma).

1.3.3 Synovial sheath of tendons

Synovial sheath of tendon (vagina synovialis tendinis) differs from synovial bursa by greater size (length and width) and doublewall.Itembracesmovingtendonofmusclelikeatubefilled with synovia. Thus synovial sheath provides not only function of bursa, but also strengthens tendon of muscle along its length. Sheaths are in areas of carpal, tarsal and digital joints.

1.3.4Trochlea

Trochlea (trochlea) is a part of tubular bone epiphysis of shape, over which muscles leap. They are presented as bony shelf and groove, where muscle tendon lies. Due to it tendons don’t move aside and leverage of force application increases.

1.3.5 Sesamoid bones

Sesamoid bones (ossa sesamoidea) form in areas of heaviest stress of muscles and are located inside tendons. They change the angle of muscle attachment and thus improves conditions of muscle work by decreasing rubbing. Sometimes they arecalled“ossificatedpartsoftendons”,butyoushouldremember, that they go through two stages of development (connective tissue and bone tissue). The biggest sesamoid bone of an organism is knee cap (patella).

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PART 2. SPECIAL MYOLOGY

All body muscles are divided into 3 groups according to disposition on the skeleton: muscles of the head, muscles of the neck, the trunk and the tail, muscles of the limbs.

Table 5

2.1Muscles of the head

The muscles of the head are divided by function and topography into mimic, masseteric, muscles of the eyelids, muscles of the pinnae and short muscles of the head and neck.

The masseteric muscles are situated mostly in cranium area and attach to mandibula by one of ends of its tendon. They effect on temporo-mandibular joint, providing movements of lower jaw, participate in chewing processes and grinding of food.

Table 6

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The mimic muscles are in facial part of the skull and are presented by thin muscle bundles. As distinguished from other muscles they mostly have only one attachment point with bones, by the other tendon they are attached to the skin. Due to it the mimic muscles move the skin and make folds and wrinkles on it during contraction.

Table 7

Mimic muscles

The muscles of eyelids are in areas of orbit and are dilatators by function. They comprise levator of upper eyelid and depressor of lower eyelid.

The muscles of pinnae attach around basement of pinnae and set superficially. They comprise levators, flexors, abductors, adductors and rotators.

The short muscles of the head and neck effect on atlo- occipitalandatlo-axialjointsandaredividedintogroupsaccording to direction of muscular bundles (straight and oblique).

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Table 8

Short muscles of the head and neck

2.2 The muscles of the neck, trunk and tail

They are united into four groups: muscles of the thoracic girdle, muscles of the vertebral column, muscles of the thorax, muscles of the abdominal wall.

2.2.1 The muscles of the thoracic girdle

Muscles of the thoracic girdle connects trunk and forelimbs. Proximal tendon is attached to the trunk and distal – to the scapula or brachium. According to the point of attachment of proximal tendon, muscles of the thoracic girdle are divided into groups: muscles of dorsal attachment (attach along vertebrates and their tendons) and muscles of ventral attachment (attach along sternum and cartilages of the ribs).

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Table 9

Muscles of the thoracic girdle

This group of muscles provide movement of the limb forward and pull it backwards, also it aids to flex, extend androtate in the shoulder joint.

2.2.2 The muscles of vertebral column

These muscles lie on dorsal and ventral surface of vertebral column.On dorsalsurface,thereareextensorsthatlifttheheadand neck, deepen the lumbus and lift the tail. Extensors that lie on lateral surface of vertebral column during unilateral contraction (left or right) provide side movement of the vertebral column.

On ventral surface there are flexors, that depress the head and neck, curve the lumbus and depress the tail. According to its topography they are divided into two groups.

Table 10

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According to topography muscles of the neck are divided into 5 layers to each other.

Table 11

Layers of muscles of the neck

2.2.3 The muscles of thorax

The muscles of the thorax provide respiratory movements. One group of the muscles extend the thorax during inhalation – it isinspiratorymuscle;anothergroupofmusclesdecreasethethorax during expiration – it is expiratory muscles. Due to different function this groups of muscles are situated differently: inspirators lie from ribs dorsally and cranially (dorsoproximal direction), expirators lie from ribs caudally and dorsally (dorsocaudal direction).

Table 12

The muscles of thorax

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