Glossary of Anatomy Muscles 300-325

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External Intercostals innervation
Intercostal nerves
Semispinalis origin and insertion
origin: Transverse processes of C7-T12; insertion: Occipital bone (capitis) and spinous processes of cervical (cervicis) and thoracic vertebrae T1-T4 (thoracis)
Quadratus Lumborum action
Flexes vertebral column laterally when acting separately; when pair acts jointly, lumbar spine is extended and 12th rib is fixed; maintains upright posture
Quadratus Lumborum innervation
Spinal nerves (dorsal rami)
Spinalis origin and insertion
origin: Spines or upper lumbar and lower thoracic vertebrae; insertion: Spines of upper thoracic and cervical vertebrae
Semispinalis action
Extends vertebral column and head and rotates them to opposite side; acts synergistically with sternocleidomastoid muscles of opposite side
Semispinalis innervation
Spinal nerves (dorsal rami)
Longissimus origin and insertion
origin: Transverse processes of lumbar through cervical vertebrae; insertion: Transverse processes of thoracic or cervical vertebrae and to ribs superior to origin as indicated by name; capitis inserts into mastoid process of temporal bone
Spinalis action
Extends vertebral column
Spinalis innervation
Spinal nerves (dorsal rami)
Iliocostalis origin and insertion
origin: Iliac Crests (lumborum); Inferior 6 ribs (thoracis); Ribs 3 to 6 (cervicis); insertion: Angles of ribs (lumborum and thoracis); Transverse processes of cervical vertebrae C6-C4 (cervicis)
Longissimus action
Thoracis and cervicis act together to extend vertebral column and acting on one side, bend it laterally; capitis extends head and turns the face toward same side
Longissimus innervation
Spinal nerves (dorsal rami)
Splenius origin and insertion
origin: Ligamentum nuchae, spinous processes of vertebrae C7-T6; insertion: Mastoid process of temporal bone and occipital bone capitis); transverse processes of C2-C4 vertebrae (cervicis)
Iliocostalis action
Extend vertebral column; maintain erect posture; acting on one side, bend vertebral column to same side
Iliocostalis innervation
Spinal nerves (dorsal rami)
Dorsal Interossei origin and insertion
origin: Sides of metacarpals; insertion: Extensor expansion over first phalanx of fingers 2-4 on side opposite midaxis of hand (finger 3), but on both sides of finger 3
Splenius action
Act as a group to extend or hyperextend head; when splenius muscles on one side are activated, head is rotated and bent laterally toward same side
Splenius innervation
Cervical spinal nerves (dorsal rami)
Palmar Interossei origin and insertion
origin: The side of each metacarpal that faces the midaxis of the hand (metacarpal 3, where it’s absent); insertion: Extensor expansion on first phalanx of each finger (except finger 3), on side facing midaxis of hand
Dorsal Interossei action
Abduct (diverge) fingers; extend fingers at interphalangeal joints and flex them at metacarpophalangeal joints
Dorsal Interossei innervation
Ulnar nerve
Lumbricals origin and insertion
origin: Lateral side of each tendon of flexor digitorum profundus in palm; insertion: Lateral edge of extensor expansion on first phalanx of fingers 2-5
Palmar Interossei action
Adductors of fingers: pull fingers in toward third digit; act with lumbricals to extend fingers at interphalangeal joints and flex them at metacarpophalangeal joints
Palmar Interossei innervation
Ulnar nerve

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