Back Myology

Question 1

Trapezius muscle

Innervation, origin, function.

Answer 1

Motor: spinal accessory nerve
Sensory: CN 3 and 4
Origin: occipital bone, ligamentum nuchae, and spinous processes of T10-T12
Insertion: lateral third of the clavicle, acromion, and scapular spine
Function: elevates, depresses, rotates, and retracts scapula

Question 2

Latissimus dorsi

Answer 2

Innervation: sixth, seventh, and eighth Cervical nerves via the thoracodorsal nerve
Origin: Spine T7, spinous process and supraspinous ligaments of all lower thoracic, lumbar, and sacral vertebrae, posterior third of iliac creat, last four ribs, and interior angle of scapula
Insertion: floor of bicipital groove of numerous after spiraling around teres major
Action: extends, adducts, and medially rotates the arms, also helps with deep inspiration and forced expiration

Question 3

Levator Scapulae

Answer 3

Innervation: dorsal scapular nerve and direct branches of spinal nerves C03 and C04
Origin: Transverse processes of C01-C04
Insertion: superior part of medial border of scapula
Actions: elevates the scapula medially and upward

Question 4

Rhomboid major

Answer 4

Innervation: dorsal scapular nerve
Origin: spinous processes of T3 to T5
Insertion: medial border of scapula below scapular spine
Action: steadies the scapula and moves the inferior angel backward and upward

Question 5

Rhomboid minor

Answer 5

Innervation: dorsal scapular nerve
Origin: spinous processes of C7 to T1
Insertion: medial borer of the scapula above the scapular spine
Action: steadies the scapula moving the inferior angle backwards and upwards

Question 6

Serratus posterior superior

Answer 6

Innervation: intercostal nerves 2-5 (T1-T5)
Origin: the supraspinal ligament, the ligamentum nuchae, and the spinous processes of the upper two or three thoracic vertebrae (T1-T3) and then C7
Insertion: upper borders of ribs 2-5
Action: elevates the upper ribs

Question 7

Serratus posterior inferior

Answer 7

Innervation: intercostal nerves 9-12 (T9-12)
Origin: Supra spinal ligament and the spinous process of L1-L3 and then T11 and T12
Insertion: lower borders of ribs 9-12
Action: draws the lower ribs backwards and downward

Question 8

Splenius capitis

Answer 8

Innervation: Dorsal rami of middle cervical spinal nerves
Origin: Lower half of ligamentum nuchae and spinous processes of seventh Cervical vertebra through thoracic C7-T3
Insertion: Mastoid processes of temporal bone and occipital bone
Action: supports the head in the erect position, draws head directly backward, and draws the head to one side and rotates it to turn face to the same side

Question 9

Splenius cervicis

Answer 9

Innervation: dorsal rami of middle cervical spinal nerves
Origin: lower half of ligamentum nuchae and spinous processes of C7 to T3
Insertion: mastoid process of temporal bone and occipital bone
Action: supports the head in the erect position, draws backward, draws head to one side and slightly rotates it, turning face to same side

Question 10

Iliocostalis lumborum

Answer 10

Innervation: dorsal rami of spinal nerves, thoracic and upper lumbar nerves
Origin: iliac crest and lateral portion of the common erector spinae tendon
Insertion: inferior borders of the angels of the lower six and seventh ribs
Action: extends, laterally flexes, and aids in rotation of the spine. Can depress ribs

Question 11

Iliocostalis thoracis

Answer 11

Innervation: dorsal primary rami of C8, thoracic, and upper lumbar nerves
Origin: upper borders of the angels of the lower six ribs medial to the tendons of insertion of the iliocostalis lumborum
Insertion: into the upper borders of the angels of the upper six ribs and into the back of the transverse process of the seventh Cervical vertebra

Question 12

Iliocostalis cervicis

Answer 12

Innervation: dorsal rami of Cervical vertebrae C4-C6
Origin: upper borders of the angels of the lower six ribs and into the back of the transverse process of the seventh cervical vertebrae
Insertion: into the upper borders of the angles of the upper six ribs and into the back of the transverse process of the seventh cervical vertebra
Action: extends, laterally flexes, and aids in rotation of the spine

Question 13

Longissimus thoracis muscle

Answer 13

Innervation: dorsal primary rami of the thoracic and lumbar spinal nerves
Origin: the whole length of the posterior surfaces of the transverse processes and the accessory processes of the lumbar vertebrae and lumbodorsal fascia
Insertion: by the rounded tendons into the tips of the transverse process of all thoracic vertebrae and by the fleshy processes into the lower nine or ten ribs between their tubercles and angles
Action: extends and laterally flexes the spine and also helps compress the ribs

Question 14

Longissimus cervicis muscle

Answer 14

Innervation: dorsal primary rami of the thoracic and lower cervical spinal nerves
Origin: transverse processes of the upper four or five thoracic vertebrae
Insertion: posterior tubercles of the transverse processes of cervical vertebrae
Action: extends and laterally flexes the spine

Question 15

Longissimus capitis

Answer 15

Innervation: dorsal primary rami of the middle and lower cervical spinal nerves
Origin: transverse processes of the upper four or five thoracic vertebrae and articulate processes of the lower three or four cervical vertebrae
Insertion: posterior margin of the mastoid process, beneath the splenius capitis and sternocleidomastoid
Action: together with other longissimus: extend the head
By itself: bends the head and turns it to face the same side

Question 16

Spinalis thoracis

Answer 16

Innervation: dorsal rami of the upper cervical nerves
Origin: spinous processes of the first two lumbar and the last two thoracic vertebrae
Insertion: spinous processes of the upper thoracic vertebrae - number varies between 4 and 8
Action: extends the spine

Question 17

Spinalis cervicis

Answer 17

Innervation: dorsal rami of the upper cervical nerves
Origin: ligamentum nuchae, spinous process of the seventh cervical, and sometimes from the spinous process of the first and second thoracic vertebrae
Insertion: spinous process of vertebrae C2-C5
Action: extends the head

Question 18

Semispinalis cervicis muscle

Answer 18

Innervation: dorsal rami of spinal nerves
Origin: transverse processes of T1-T6
Insertion: spinous process of C2-C7
Action: w/ other semispinalis: extend vertebral column
Unilaterally: draws head to one side and rotates it so that the face is turned to the opposite side

Question 19

Semispinalis thoracis muscle

Answer 19

Innervation: dorsal rami of spinal nerves
Origin: transverse processes of T6-T12
Insertion: Spinous processes of C2-C7
Action: unilaterally draws head to one side and rotates so that face is turned to opposite side

Question 20

Semispinalis capitis muscle

Answer 20

Innervation: dorsal rami of spinal nerves
Origin: tips of T6 or T7 and C7 vertebrae and from articular processes of 3C about that
insertion: between the superior and inferior nuchal lines of the occipital bone
Action: unilaterally - draws head directly backward and rotates it so that the face is turned to the opposite side

Question 21

Multifidus muscle

Answer 21

Innervation: posterior branches
Origin: sacrum, posterior iliac spine, mammillary processes of lumbar vertebrae, transverse processes of thoracic vertebrae, and articular processes of cervical vertebrae C4-C7
Insertion: spinous processes 2-4 vertebrae superior to the origin
Action: stabilizes the vertebrae in local movements of vertebral column

Question 22

Rotatores thoracis breves

Answer 22

Innervation: cervical, thoracic, and spinal nerves (post. Branch)
Origin: transverse processes of each thoracic vertebrae
Insertion: spinous processes of vertebrae above each origin
Action: extend and rotate vertebral column

Question 23

Rotatores thoracis longi

Answer 23

Innervation: cervical, thoracic, and post spinal nerves
Origin: transverse process of each thoracic vertebrae
Insertion: spinous process of the vertebra two above that of each origin
Action: extend and rotate the vertebral column

Question 24

Intertransversearii

Answer 24

Originates at transverse process and inserts in adjacent superior vertebra

Innervation by thoracic, cervical, and lumbar spinal nerves

Question 25

Rectus capitis posterior minor

Answer 25

Innervation: branch of the dorsal primary division of the Suboccipital nerve
Origin: tubercle of the posterior arch of the atlas
Insertion: medial part of the inferior nuchal line of the occipital bone and the surface between it and the foramen magnum
Action: extends head at the neck