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myology 1

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									Myology
     Section 1 the general description

   The muscle of locomotor system are the
    skeletal muscles.
   All of them are attached by at least one
    end to some part of the skeleton.
   The skeletal muscle is voluntary muscle
    undering the voluntary control.
   About 40% the body weight is shared by
    the skeletal muscle.
The morphology of skeletal muscles

          belly: consists of muscle fibers and is
            able to contract
          tendon: consists of fibrous tissue and
            is unable to contract
       According to the shape of muscles:
       Long muscle
       Short muscle
       Flat muscle
       Orbicular muscle




long muscle   flat muscle   orbicular muscle   short muscle   digastric
The origin, insertion and action of skeletal muscles

  Origin: the fixed attachment.
  Insertion: the movable attachment.
Agonists: produces most of the force during a
           particular joint action;
Antagonist: oppose the action of a prime mover;
Synergist: cooperate in performing an action;
Fixators: prevents a bone from moving.
   Nomenclature of skeletal muscles
According to shape:
such as deltoid m.; rhomboid m.
According to location:
such as tibialis ant.; tibialis post.
According to origin and insertion:
sternocleidomastoid m.
According to action:
 supinator
Mixed name:
 extensor carpi radialis longus
 flexor carpi radialis
The supplementary structures of
   skeletal muscles
1. Fascia
  – Superficial fascia
  It is found in the subcutis in
      most regions of the body.
  In different individuals and
      different part of the body,
      the thickness is different.
  Devoid of fatty tissue, there are
      the trunks of the
      subcutaneous vessels and
      nerves, the superficial
      lymphonotes, the mammary
      gland and cutaneous muscles.
– Deep fascia:
It is a dense inelastic
  fibrous membrane
  forming a strong
  investment.
   intermuscular septum:
 In the limb, the fasciae
 give off septa which
 separate the groups of
 muscle and attached to the
 periosteum.
   retinaculum: the deep
 fascia is thickened at the
 wrist and ankle to form the
 retinaculum that maintains
 its underlying tendons.
2. Synovial bursa
• It is a connective tissue sac with a slippery inner
  surface, and filled with synovial fluid.
• It presents in the place where tendon rubs
  against bone, ligament, or other tendon, or
  where skin moves over a body prominence.
3. Synovial sheath of tendon
a double layered synovial sheath, in
  which the tendon runs, is usually
  located in the hand and foot.
Fibrous layer
Synovial layer parietal layer
               visceral layer
4. Sesamoid bones
• Be developed in the tendons.
• Minimize the friction.
• Change the direction of pulling force and
  strengthen the force of the muscle.
         Arrangement of muscles
•   muscles are arranged around the axis of joints:

•   around coronal axis flexor and extensor

•   around sagittal axis abductor and adductor

•   around vertical axis med. and lat. Rotator
 Section 2 The muscle of trunk

The muscles of back
The muscle of thorax
The diaphragm
The muscle of abdomen
The muscle of perineum
   The Muscles of Back

                    Trapezius
Superficial group   Latissimus dosi
                    Levator scaplae
                    Rhomboid muscle

Deep group: concerned with the
            movement of the
            vertebral column.
                     Trapezius
• Arises from the external occipital
  protuberance, superior nuchal line,
  spine of seventh cervical vertebra,
  cervical ligament, the spinous
  process and supraspinal ligaments of
  all thoracic vertebrae.
• Be attached to the lateral one third
  of the clavicle, the acromion and the
  spine of scapula.
• steadies, ascends, descends, retracts
  and rotates the scapula and extends
  the head.
            Latissimus dorsi
Arises from the spinous
 processes of lower six thoracic
 vertebrae, the thoracolumbar
 fascia.
Be inserted into the floor of the
 inertubercular sulcus.
extends, adducts and medially
 rotates humerus.
              Erector spinae
It is a collective name for a
 group of deep muscles of
 the back.
It lines in the vertebral
 groove on each side of
 vertebral spines.
When acting on one side it
 bends and rotates the
 spinal column toward the
 oppsite side. When acting
 on both sides it extends the
 spinal column.
       The Muscles of Thorax

Extrinsic muscles: arise from the outer of the thorax
                   and are insert into the shoulder
                   girdle or the humerus.


Intrinsic muscles: be located between the ribs and
                   the sternum or vertebrae.
               Extrinsic muscles

Pectoralis major
• Arises from anterior surface of the
  medial half of the clavicle, the
  anterior surface of the sternum,
  the six costal cartilages and the
  aponeurosis of obliquus externus
  abdominis.
• Inserted into the crest of greater
  tubercle of humerus.
• adducts, flexes and medially
  rotates arm.
                   Pectoralis minor

• Arises from the front of the external
 surface of the third to fifth ribs
• Be inserted into the coracoid process
 of the scapule.
• Stabilizes scapula by drawing it
 forward and downward. When the
 scapule is fixed, it helps the inspiration.
                Serratus anterior
• Arises by a series of slips from
 the external surface of the
 upper 8-9 ribs.
• Be inserted into the entire
 anterior surface of medial
 border of the scapula.
• Holds the scapula against chest
 wall and pulls it forward.
Intrinsic muscles
external intercostal m.
 pull the ribs upward, increase
 the thoracic capacity, help
 inspiration
internal intercostal m.
 pull the ribs downward,
 decrease the thoracic capacity,
 help expiration
                   The diaphragm

Location: between thoracic and abdominal cavity.

structures:
 peripheral part: muscular part
                  sternal part
                  costal part
                  lumbar part
 central part: central tendon
 two weak areas:
        sternocostal triangle
        lumbocostal triangle
         Three openings in the diaphragm
Aortic hiatus
-12th thoracic vertebra
-the abdominal aorta and the thoracic duct

Esophageal hiatus
-10th thoracic vertebra
-the esophagus and the vagal trunks


Vena cava foramen
-8th thoracic vertebra
-the inferior vena cava
Diaphragm hernia
                   Action
Help Inspiration and assists in raising intra-
 abdominal pressure.
 The Muscles of Abdomen


                      obliquus externus abdominis
                      obliquus internus abdominis
Anterolateral group
                      Transversus abdominis
                      Rectus abdominis


Posterior group:Quadratus lumborum
                    Rectus abdominis



                   obliquus internus
                   abdominis

aponeurosis


                   obliquus externus
                   abdominis


              inguinal ligament
                                                   Transversus abdominis
                                  Tendinous
                                   intersections
Sheath of rectus abdominis




         aponeurosis
Linea alba
The actions of anterolateral group
 Support and protect the viscera;
 Maintian and to increase the
  intrabdominal pressure;
 Move the vertebral column in flexion,
  rotation and help to maintain posture.
   Posterior group

Quadratus lumbrum and psoas
  major
Actions:
 Fixes and lowers the 12th rib;
 Bends the trunk
 Extend the lunbar region of
  the vertebral column.
         Section 3
The muscles of head and neck
  The muscles of head

Facial muscles
Masticatory muscles
              The facial muscles
Characteristic:
• Arise from the surface of skull and are inserted
  onto the skin of the face.
• Pull the skin in various directions to express the
  emotions.
• Surrounded the openings act as sphincters and
  dilators.
                                 Epicranius
 occipitofrontalis                         Actions: the frontal belly draw
                                           the scalp forward, throwing
Epicranial aponeurosis
                                           the skin of the forehead into
Frontal belly                              transverse wrinkle. The
                                           occipital belly draws the scalp
                                           backward.




                         Occipital belly
orbicularis oculi




          Muscles around the mouth
The masticatory muscles

Masseter: elevates and backward pulls the mandible.
Temporalis: elevates the mandible.
Medial pterygoid: elevates and protrudes mandible.
Lateral pterygoid: protrude mandibel and depress chin.
 The muscles of neck

   By their positions, the muscles of neck
are divided into four groups: superficial,
suprahyoid, infrahyoid and deep.

I. The superficial group
Platysma
Actions: tenses skin of neck,
     draw corners of mouth
     down, and assists in
     depressing mandible.
     Sternocleidomastoid


ACTION
when acting together turns the
 head upward;
when acting alone the head is
 inclined laterally and the face is
 rotated to the opposite side
 Ⅱ. The hyoid muscles
 1. The suprahyoid muscles
 Action: elevate the hyoid bone and help swallowing.

geniohyoid


                Mylohyoid
               Stylohyoid                       Digastric




                               Hyoid bone
2. The infrahyoid muscles
 Action: depress the hyoid bone.
Ⅲ. Deep cervical muscles
    scalenus anterior
    scalenus medius
    scalenus posterior
Scalene fissure: above the
   first rib, between the
   scalenus anterior and
   scalenus medius.
   brachial plexus and
   subclavian artery pass
   through it.

								
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