Muscles of the back

what are extrinsic muscles?

first muscles seen

superficial and intermediate

what innervates the extrinsic muscles

ventral primary rami of spinal nerves

(trapezius is innervated by cranial nerve)

what are the superficial extrinsic muscles?

trapezius

latissimus dorsi

rhomboid major and minor

levator scapulae

what are the intermediate extrinsic muscles?

serratus posterior superior and serratus posterior inferior

What is the origin of the Trapezius?

spinous process

supraspinous ligament

ligamentum nuchae

superior nuchal line

external occipital protuberance

what is the insertion of the trapezius?

spine and acromion of the of scapula

what nerve innervates the trapezius?

spinal accessory nerve (CN XI)

action of trapezius?

superior- elevates

middle- retracts scapula

inferior- depresses

connects shoulder girdle to axial skeleton

What is the origin of the latissimus dorsi?

spinous process

thoracolumbar fascia

iliac crest

ribs

what is the origin of the latissimus dorsi

medial aspect of humerus

action of latissimus dorsi

extends, adducts, and medially rotates the humerus w

What nerve innervates the latissimus dorsi?

thoracodorsal nerve

what is the origin of the rhomboid major and minor

spinous process

what is the insertion of the rhomboid major

medial border of scapula inferior to the spine

what is the insertion of the rhomboid minor

the medial border of the scapula at the level of spine

action of rhomboid major and minor?

retraction and downward rotation of scapula

holds scapula to thoracic wall

what is the innervation of the rhomboid major/minor

dorsal scapular nerve

what is the origin of the levator scapulae

transverse processes

what is the insertion of the levator scapulae

medial border of the scapula superior to the scapular spine

what is the innervation of the levator scapulae

dorsal scapular nerve

what is the origin of the serratus posterior superior and inferior

spinous processes of vertebrae

what is the insertion of the serratus posterior superior

superior borders of ribs 2-5

what is the insertion of the serratus posterior inferior

inferior borders of ribs 9-12

what innervates the serratus posterior S/I?

ventral primary rami

action of serratus posterior S/I?

respiration

what is the origin of the splenius muscles

spinous processes

what is the insertion of the splenius muscles

transverse processes

superior nuchal line

mastoid process

what is the action of the splenius muscles

hold deep neck muscles into position

unilaterally and bilaterally **

what is the innervation of the splenius muscles

dorsal primary rami

what is the erector spinae

principal muscle for erect posture

extensor of vertebral column

helps with all movements EXCEPT flexion

what does the erector spinae split into

Iliocostalis, Longissimus, Spinalis

Iliocostalis

arises from sacrum — lumbar vertebral spines — posterior iliac crest — extends to ribs — lower cervical transverse processes

longissimus

intermediate bundle — reaches ribs OR transverse processes in T/C regions with the highest bundle reaching the mastoid process of skull

spinalis

most medial

evident in thoracic region

highly ligamentous

transversospinalis

DEEP to the erector spinae

all fibers are runnings obliquely and superiorly

originate from transverse processes and pass to spinous processes

extends and rotates

what innervates the transversospinalis

dorsal primary rami

what are the 3 groups of the deep layer of erector spinae

semispinalis

multfidus

rotatores

semispinalis

“half of spine”

fibers run superomedially to occipital bone

spinous process in T/C regions

extends head

4-6 vertebral levels

Multifidus

shorter

thicker in lumbar

fibers pass obliquely

2-4 vertebral levels

stabilizes vertebrae

rotatores

entire length (most evident in thoracic region)

stabilizes vertebrae

transverse process of one vertebra to lamina and transverse process OR spinous process

interspinales

one spinous process to next

inbetween spine

extension rotation

intertransversarii

one transverse process to next

inbetween transverse processes

lateral flexion and stability le

levator costarum origin and insertion?

ONLY in THORACIC

origin: transverse process

insertion: ribs

innervate: dorsal primary rami

action of levator costarum

lateral flexion, elevate ribs, respiration