Back Muscles

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Back Muscles
2014-01-11 18:40:51
Back Muscles

Information on back muscles Origin: Insertion: Action: Innervation:
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    • Splenius Capitis
    • Origin: Ligamentum Nuchae; spinous processes of 7th cervical and first 3 or 4 thoracic
    • Insertion: Mastoid process and occipital bone
    • Action: Rotation of the head and cervical vert. column to same side.
    • Innervation: Posterior rami of middle cervical spinal nerves
    • Splenius Cervicis
    • Origin: spinous processes of about the third to sixth thoracic vertebrae
    • Insertion: laterally on the upper two to four cervical transverse processes.
    • Action:rotate the head and cervical vertebral column toward the same side. When they act bilaterally, they aid in extension of the neck.
    • Innervation: Posterior rami of lower cervical spinal nerves
    • Serratus Posterior Superior
    • Origin:the lower part of the ligamentum nuchae and the spinous processes of the
    • seventh cervical and upper two or three thoracic vertebrae.
    • Insertion: on the upper ribs, usually the second to the fifth.
    • Action: to assist in elevating the ribs and therefore increasing the size of the thorax.
    • Innervation: from branches of the first three or four intercostal nerves and therefore from anterior rami of spinal nerves.
    • Serratus Posterior Inferior
    • Origin: the lower two thoracic and upper two lumbar spinous processes
    • Insertion:on the lower three or four ribs
    • Action:draw the lower ribs downward to enlarge the thoracic cavity and steady these ribs against upward pull of the diaphragm.
    • Innervation: the ninth to twelfth intercostal nerves
    • Erector Spinae (Iliocostalis, Longissimus, Spinalis)
    • Origin: This muscle group has a common tendinous and fleshy origin from the
    • posterior surface of the sacrum, the iliac crest, and the spinous
    • processes of the lumbar and last two thoracic vertebrae.
    • Insertion:As the erector spinae is followed upward, however, it divides into three
    • series of muscles, of which only the lateral two are well developed.
    • Action:
    • Bilateral action: extension of vertebral column
    • Unilateral action: to bend vertebral column toward same side (lateral flexion)
    • Innervation: All parts of the erector spinae receive innervation from posterior rami of spinal nerves.
  1. Iliocostalis (Lumborum, Thoracis, Cervicis)

    • The iliocostalis lumborum, although sharing the common tendon, has its origin especially from the iliac crest and the sacrum. Its insertion is by a series of slips into the lower borders of the lower six or seven ribs.
    • The iliocostalis thoracis consists of a number of fascicles that take origin from the upper borders of the lower six or seven ribs, medial to the insertions of the iliocostalis lumborum. The insertion is on the lower borders of the upper six ribs.
    • The iliocostalis cervicis has its origin from the angles of the upper six ribs, medial to the insertions of the iliocostalis thoracis. Its insertion is on the transverse processes of about the fourth to sixth cervical vertebrae.
    • Longissimus thoracis
    • Origin:
    • Intermediate part of common tendon
    • Insertion:
    • Lower nine or ten ribs; adjacent transverse processes of vertebrae

    • Longissimus cervicis
    • Origin:
    • Transverse processes of upper four to six thoracic vertebrae
    • Insertion:
    • Transverse process of second to sixth cervical vertebrae

    • Longissimus capitis
    • Origin:
    • Tendons of origin of longissimus cervicis; articular processes of lower four cervical vertebrae
    • Insertion:
    • Mastoid process of skull
    • Multifidus
    • origin: from the sacrum and posterior
    • superior iliac spine; mammillary processes of the lumbar vertebra;
    • transverse processes of the thoracic vertebrae; and articular processes
    • of the lower cervical vertebrae.

    • Insertions on the spinous processes of the
    • lumbar vertebrae through the second cervical vertebra. These muscles
    • form a continuous mass from the upper end of the sacrum to the second
    • cervical vertebra. The multifidus are particularly heavy in the lumbar
    • region, thinner in the thoracic region, and thicker again in the upper
    • cervical region, but they do not extend to the skull.

    • bilateral action of the multifidus is to
    • extend the vertebral column; unilaterally, they produce rotation to the
    • opposite side and laterally flex the column.

    innervation from the posterior rami of spinal nerves.
    • Rotatores
    • Origin: Transvers Process
    • Insertion: base of spinous process (short span one vertabrae, long span 2)
    • Action: rotate and extend the vertebral column.
    • Innervation: posterior rami of the spinal nerves.
    • Trapezius
    • Origin: Occipital bone and spinous processes of thoracic vertebraeĀ 
    • Insertion: Clavicle and scapula (acromion and scapular spine)
    • Action:
    • Innervation:
    • Latissimus Dorsi
    • Origin: Spinous processes of lower thoracic vertebrae, ribs and lumbar vertebrae
    • Insertion: Intertubercular groove of humerus
    • Action: Extension, adduction, and medial rotation at shoulder
    • Innervation: Thoracodorsal, C6,7,8
    • Rhomboid Minor
    • Rhomboid Major
    • Origin:
    • Insertion
    • Action: Adduct and elevate the scapula, and rotate it so the glenoid cavity faces caudally
    • Innervation: Dorsal scapular, C4,5
    • Levator Scapulae
    • Origin: Transverse processes of C1-C4
    • Insertion: Medial border of scapula between superior angle and root of spine
    • Action: Elevates scapula
    • Innervation: Cervical 3, 4 and Dorsal scapular C4, C5