muscular

• Muscles


  Organs that contract to produce movement
• Muscular system


  Includes all the skeletal or striated muscles within the body
• Classifications of muscles


  • Skeletal muscle
  • Smooth and cardiac muscle
• Skeletal muscle


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

  
• Epimysium


  Connective tissue around an entire muscle and the deep fascia of the muscle
• Perimysium


  Shift surrounding the bundles of muscle fiber
• Endomysium


  Connective tissue between individual muscle fibers
• Belly


  Thick fleshy central part of the muscle tissue
• Origin


  The less movable; 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
• Flexor


  Muscles that bends a limb at its joint or decreases the joint angle

  
• Extensor


  Muscles that straightens a limb or increases the joint angle
• Triceps


  Generally have three divisions (head)
• Quadriceps


  Generally have four divisions (head)
• Azygous


  Not paired
• Pectoralis major


  Origin - the deep fascia of the cranial part of the thorax and the caudal part of the deep fascia of the neck, the caudal part of the clavicle, and the cranial part of the sternum and the first sternebrae or manubrium. 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)

  
• Braciocephalicus


  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


  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


  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


  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


  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


  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


  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

  
• Deltoideus


  Origin - The spine and acromial process of the scapula. Insertion - The deltoid tuberosity. Action - To flex the shoulder. Innervation - Axillary nerve

  
• Infraspinatus


  Origin - The infraspinous fossa. Insertion - A small, circumscribed area on the lateral side of the greater tubercle of the humerus. Action - To extend or flex the joint, depending on the degree of extension or position of the joint when the muscle contracts. To abduct the shoulder and to rotate the arm laterally. Innervation - Suprascapular nerve

  
• Teres minor


  Origin - The infraglenoid tubercle and distal third of the caudal border of the scapula. Insertion - The teres minor tuberosity of the humerus. Action - To flex the shoulder and rotate the arm laterally. Innervation - Axillary nerve

  
• Supraspinatus


  Origin - The supraspinous fossa. Insertion - The greater tubercle of the humerus, by a thick tendon. Action - To extend the shoulder. Innervation - Suprascapular nerve

  
• Subscapularis


  Origin - The subscapular fossa. Insertion - The lesser tubercle of the humerus. Action - To adduct and extend the shoulder. Innervation - Subscapular nerve

  
• Teres major


  Origin - The caudal angle and adjacent border of the scapula; the caudal surface of the subscapularis. Insertion - The teres major tuberosity of the humerus. Action - Flex the shoulder and rotate the arm medially. Innervation - Axillary nerve

  
• Coracobrachialis


  Origin - The coracoid process of the scapula. Insertion - The crest of the lesser tubercle of the humerus proximal to the teres major tuberosity. Action - To adduct and extend the shoulder. Innervation - Musculocutaneous nerve

  
• Tensor fascia antebrachii


  Origin - The fascia covering the lateral side of the latissimus dorsi. Insertion - The olecranon. Action - To extend the elbow. Innervation - Radial nerve

  
• Triceps brachii - long head


  Origin - the caudal border of the scapula. Insertion - The olecranon. Action - To extend the elbow and flex the shoulder. Innervation - Radial nerve

  
• Triceps brachii - lateral head


  Origin - laterally on humerus; crest of the greater tubercle of the humerus. Insertion - The olecranon. Action - To extend the elbow. Innervation - Radial nerve

  
• Triceps brachii - medial head


  Origin - medially on humerus; caudal tuberosity of teres major, crest of the lesser tubercle. Insertion - The olecranon. Action - To extend the elbow. Innervation - Radial nerve

  
• Triceps brachii - accessory head


  Origin - The neck of the humerus. Insertion - The olecranon. Action - To extend the elbow. Innervation - Radial nerve