Muscular System Part 1

• Muscles


  Organs that contract to produce movement
• Muscular system


  • Skeletal or striated muscles
  • Smooth and cardiac muscle
• Skeletal muscle


  • Composed of organization of structures: Epimysium, Perimysium, Endomysium

  
• Belly


  Thick fleshy central part of the muscle tissue
• Origin


  The less movable part; in the limbs, it is the proximal attachment
• Insertion


  The more movable part; in the limb, it is the more distal attachment
• Fleshy attachment


  The apparent direct attachment of muscle to bone
• Tendinous attachment


  The dense connective tissue connecting the spindle or pennate muscle to bone
• Aponeurotic attachment


  The flat, tendinous sheet associated with flat muscles such as those of the abdominal wall
• Extrinsic muscles


  Run from one region of the body to another and alter the position of the whole part
• Intrinsic muscles


  Lie completely within one region of the body where they have their origin and insertion
• Derivations of muscle names based on range of action (Part 1)

  • Abductor
  • Adductor
  • Flexor
  • Extensor
• Derivations of muscle names based on range of action (Part 2)

  • Levator
  • Depressor
  • Rotator
  • Supinator
  • Pronator
• Derivations of muscle names based on location

  • Pectoral
  • Epaxial
  • Intercostal
  • Infraspinatus
  • Supraspinatus
  • Inferior
  • Superior
  • Medius
  • Externus
  • Internus
  • Orbicularis
  • Rectus
  • Oblique
  • Transverse
  • Sphincter
  • Minimus
  • Maximus
  • Vastus
  • Latissimus
  • Longissimus
  • Gracilis
• Derivations of muscle names based on number of parts

  • Biceps
  • Triceps
  • Quadriceps
  • Azygous

  
• Sartorius


  Named because it flexes and adducts the leg of a human to that position assumed by a tailor sitting cross-legged at work
• Gemellus


  Twinned muscle
• Gastrocnemius


  Resemble shape of a stomach
• Derivations of muscle names based on shape

  • Deltoid
  • Quadratus
  • Rhomboideus
  • Scaleneus
  • Serratus
  • Teres
• Fibrous raphe


  Seamlike union of two lateral halves of a part or organ having externally a ridge or furrow and internally usually a fibrous connective tissue septum
• Aponeurosis


  A sheet of pearly white fibrous tissue that takes places of a tendon in flat muscles having a wide area of attachment
• Fascia


  A band or sheet of connective tissue that separates muscles and other internal organs
• Innervation


  To supply with nerves
• Superficial pectoral muscle


  • Origin: the first 2 sternebrae and usually part of the third

  Insertion: the whole crest of the greater tubercle

  Action: to adduct the limb when it is not bearing weight or to prevent the limb from being abducted when bearing weight

  Innervation: Cranial pectoral nerves (C7, C8)
• Deep pectoral muscle


  • Origin: the ventral part of the sternum and the fibrous raphe between fellow muscles; the deep abdominal fascia in the region of the xiphoid cartilage

  Insertion: the major portion partly muscular, partly tendinous on the lesser tubercle of the humerus; an aponeurosis to the greater tubercle and its crest; the caudal part to the medial brachial fascia

  Action: to pull the trunk cranially when the limb is advanced and fixed; to extend the shoulder; to draw the limb caudally when it is not supporting weight

  Innervation: caudal pectoral nerves (C8, T1)
• Brachiocephalicus muscle


  • Action: to advance the limb; to extend the shoulder and draw the neck and head to the side

  Innervation: accessory nerve, and ventral branches of cervical nerves
• Sternocephalicus muscle


  • Origin: the first sternebrae or manubrium

  Insertion: the mastoid part of the temporal bone and the nuchal crest of the occipital bone

  Action: to draw head and neck to the side

  Innervation: accessory nerve and the ventral branches of cervical nerves
• Omotransversarius muscle


  • Attachment: the distal end of the spine of scapula; cranially, the wing of the atlas

  Action: to advance the limb or flex the neck laterally

  Innervation: accessory nerve
• Trapezius muscle


  • Origin: the median raphe of the neck and the supraspinous ligament from the level of the third cervical vertebra to the level of the ninth thoracic vertebra

  Insertion: the spine of the scapula

  Action: to elevate and abduct the forelimb

  Innervation: accessory nerve
• Latissimus dorsi muscle


  • Origin: the thoracolumbar fascia from the spinous processes of the lumbar and the last seven or eight thoracic vertebrae; a muscular attachment to the last two or three ribs

  Insertion: the teres major tuberosity of the humerus and the teres major tendon

  Action: to draw the free limb caudally as in digging; to flex the shoulder

  Innervation: thoracodorsal nerve (C7, C8, T1)
• Serratus ventralis muscle


  • Origin: the transverse processes of the last of the five cervical vertebrae and the first seven or eight ribs ventral to their middle

  Insertion: the dorsomedial third of the scapula (serrated face)

  Action: to support the trunk and depress the scapula

  Innervation: ventral branches of the cervical nerve and the long thoracic nerves
• Rhomboideus muscle


  • Origin: the nuchal crest of the occipital bone; the median fibrous raphe of the neck; the spinous processes of the first seven thoracic vertebrae

  Insertion: the dorsal border and adjacent surfaces of the scapula

  Action: to elevate the forelimb and draw the scapula against the trunk

  Innervation: ventral branches of cervical and thoracic nerves
• The supinator muscle is innervated by the radial nerve.
• The pronator teres muscle is innervated by the median nerve.
• The flexor carpi ulnaris is innervated by the medial nerve.
• The brachioradialis muscle is innervated by the radial nerve.
• The pronator quadratus muscle is innervated by the anterior interosseous branch of the median nerve.
• The extensor carpi ulnaris muscle is innervated by the deep branch of the radial nerve.
• The triceps brachii muscle is innervated by the radial nerve.
• The biceps brachii muscle is innervated by the musculocutaneous nerve.