Muscles of the back

Question 1

Describe the extrinsic back muscles

Answer 1

Superficial back msucles (trapezius, latissimus dorsi, levator scapular and rhomboids) Connect the upper limbs to the trunk and produce and control limb movements. Innervated by the anterior rami of the cervical spinal nerves

Intermediate (serratous posterior) is a superifical respiratory muscle

Question 2

Describe the intrinsic back muscles

Answer 2

Innervated by the posterio rami of the cervical spine and act to maintain posture and control movements of the vertebral column. These msucles extend from the plevis to the cranium and are enclosed by deep fascia that attaches medially to the nuchal ligament , the tips of the spinous processes of the verebrae, the supraspinous ligament and the median crest of the sacrum. k

Superfical layer includes the splenius msucles which lie on the lateral and posteiro aspects of the neck, covering the vertical muscles

Intermediate include the masses erector spinae which is made of three columns. The iliocostalis laterally, the longissimus intermediately and the spinalis medially

Deep has the transversospinal muscle group consisting of semispinalis multifidus and rotatores

Question 3

Describe splenius

Answer 3

Origin: arises from the nuchal ligament and psinous processes of c7-t3 or 4

Insertion

• spenlius capitus: fibres run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occiptal bone
• splenius cervicis: tubercles of transverse processes of c1-3/4

innervation: posterior rami of the cervical spinal nerves

action

• Alone: laterally felx neck and rotate head to side of active msucles
• together: extend head and neck

Question 4

Describe erector spinae (iliocostalis, longissimus, spinalis)

Answer 4

Origin: arising by a broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacroiliac liagments, sacral and inferior lumbar spinous processes and suprapsinous ligament.

Insertion

• Iliocostalis: lumborum, thoracis, cervicis; fibers run supoeriorly to angles of lower ribs and cervical transverse processes
• Longissimus: thoracis, cervicis, capitus: fibers run superiorly to ribs between tubercles and angels to transverse processes in throacic and cervical regions and to the mastoid process of the temporal bone
• Spinalis: thoracic, cervicus, capitus: fibers run superily to spinous processes in the upper thoracic region and to cranium

innervation: posterior rami of the cervical spinal nerves

action:
- bilaterally: extend veterbral column and head; as back is flexed, control movement by gradually lengthening thier fibers
- unilatearlly: laterally flex vertebral column

Question 5

Describe semispinalis (Transversospinal)

Answer 5

Origin: arises from transverse processes of C4-t12

Insertion thoracis, cervicis, capitis: fibers run superomedially to occipital bone and spinous processes in thoracic and cervical regions spanning 4-6 segments.

innervation: posterior rami of the cervical spinal nerves
action: extends head and throracic and cervical regions of vertebral column and rotates them contralaterally

Question 6

Describe Multifidus (Transversospinal)

Answer 6

Origin: Arises from posterior sacrum, PSIS, aponeurosis of erector spinae, sacroiliac ligaments, mammillary processes of lumbar vertebrea, transverses processes of t1-t3, articular processes of c4-7

Insertion: thickest in lumbar region; fibers pass obliquely superomedially to entire length of spinous processes of vertebrae

innervation: posterior rami of the cervical spinal nerves
action: stabilizes vertebrae during local movements of vertebral column

Question 7

Describe Rotatores (Transversospinal)

Answer 7

Origin : Arise from transverse processes of vertebrae; best developed in the throracic region

Insertion: fibers pass superiomedially to attach to junction of lamina and transverse process of spinous process of vertebra immediately (brevis) or 2 segments (longus) superior to vertebrae of origin.

innervation: posterior rami of the cervical spinal nerves
action: stablize vertebrae and assist with local extension and rotatory movements of verebral column; may function as organs of proprioception.

Question 8

Describe interspinales

Answer 8

Origin: superior surface of spinous processes of cervical and lumbar vertebrae

Insertion: inferior surfaces of spinous processes of vertebra superior to vertebra of origin

innervation: posterior rami of the cervical spinal nerves
action: aid in extension and rotation of vertebral column

Question 9

Describe intertransverarii

Answer 9

Origin: transverse processes of cervical and lumbar vertebrae

Insertion: transverse processes of adjacent vertebrae

innervation: posterior and anterior rami of the cervical spinal nerves

action air in lateral flexion of vertebral column, acting bilaterally, stabilize vertebral column

Question 10

Describe Levatores costarum

Answer 10

Origin: tips of transverse processes of C7 and t1-11 vertebrae

Insertion: pass inferolaterally and insert on rib between tubercle and angle

innervation: posterior rami of C8-t11

action Elevate ribs assisting respiration; assist with lateral felxion of vertebral column