RVU Anatomy – Superficial, Intermediate and Deep Muscles of the Back (Buck Book Chap. 3-4)

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Origin of Trapezius
from occipital protuberance and superior nuchal line down nuchal ligament to spinous processes of CV7-TV12

Insertion of Trapezius
Lateral superior border of clavicle, acromion and spine of the scapula

Action of Trapezius (superior fibers)
elevate scapula, some upward rotation of glenoid cavity (“socket” of shoulder joint)

Action of the Trapezius (middle fibers)
retraction of the scapula

Action of the Trapezius (inferior fibers)
upward rotation of glenoid cavity

Innervation of Trapezius
Cranial nerve XI (spinal accessory-motor)
Ventral rami of spinal nerves C3 and C4 (sensory)

Subtrapezial plexus
formed by CN XI and spinal nerves C3 and C4
integrity of CN XI is tested by shrugging shoulders against resistance

Origin of Latissimus Dorsi
-Spinous processes TV6-TV12
-Thoracolumbar fascia – all lumbar and sacral spinous processes
-Posterior one-third of the crest of the ilium
-Outer surface of ribs 9-12 (last 3-4 ribs)

Insertion of Latissimus Dorsi
floor of intertubercular (bicipital) groove of the humerus

Action of the Latissimus Dorsi
-Adducts,
-Extends,
-Medially rotates the humerus

Innervation of the Latissimus Dorsi
thoracodorsal nerve

Origin of Levator Scapulae
Transverse processes of cervical vertebrae 1-4

Insertion of Levator Scapulae
medial border of scapula from superior angle to root of spine

Action of Levator Scapulae
-Elevates scapula,
-Assists in downward rotation of glenoid cavity

Innervation of Levator Scapulae
-Dorsal scapular nerve (C5)
-3rd and 4th cervical nerve

Origin of Rhomboideus Minor
-Spinous processes of CV7 and TV1

Insertion of Rhomboideus Minor
-Medial border of scapula at root of spine (about top 1/4-1/3 of medial border of scapula)

Action of Rhoboideus Minor
-Retracts scapula
-Downwardly rotates glenoid cavity

Innervation of Rhomboideus Minor
dorsal scapular nerve

Origin of Rhomboideus Major
Spinous processes of TV2-TV5

Insertion of Rhomboideus Major
Medial border of scapula from root of spine to inferior angle (bottom 3/4-2/3 of medial border)

Innervation of Rhomboideus Major
dorsal scapular nerve

Triangle of Auscultation
-area near posterior SIXTH intercostal space; mostly devoid of muscle and bone; easier to hear
-Borders: trapezius, rhomboideus major, latissimus dorsi

Transverse Cervical Artery
-branch of thyrocervical trunk (1st portion of subclavian artery)
-passes posteriorly within posterior triangle of neck
-slips deep to trapezius
-under trapezius, MAY (50-50 chance) split into TWO branches:
1. Superficial: descends with
spinal accessory nerve
2. Deep: runs deep to levator
scapulae and rhomboides
muscles, along the dorsal
scapular nerve, participates in
scapular anastomosis

Dorsal Scapular Artery
-present in 50% of people
-arises from 2nd or 3rd portion of subclavian artery
-proceeds posteriorly between brachial plexus and neck musculature, then runs deep to levator scapulae and rhomboideus muscles, following dorsal scapular nerve and participates in scapular anastomosis

Thoracodorsal Artery
-branch of subscapular artery (3rd portion of the axillary artery)
-accompanies the thoracodorsal nerve on ventral surface of the latissimus dorsi muscle

Superficial Back Muscles
1. Muscles which attach the scapula to the torso
2. Innervated by ventral primary rami of cervical spinal nerves via brachial plexus and, for the trapezius ONLY, the spinal accessory nerve

Intermediate Back Muscles
1. Posterior muscles of respiration
2. Innervated by ventral primary rami of thoracic spinal nerves (intercostal nerves)

Deep Back Muscles
1. Muscles which extend, sidebend, and rotate the spine
2. Innervated by the dorsal rami of spinal nerves

Origin of Serratus Posterior Superior
-Nuchal ligament
-Spinous processes of CV7-TV3

Insertion of Serratus Posterior Superior
posterior surface of ribs 2-5 lateral to angle

Action of Serratus Posterior Superior
Elevates ribs during inspiration

Innervation of Serratus Posterior Superior
intercostal nerves T1-T4

Origin of Serratus Posterior Inferior
spinous processes of TV11-LV2 via thoracolumbar fascia

Insertion of Serratus Posterior Inferior
posterior surface of ribs 9-12 lateral angle

Action of Serratus Posterior Inferior
depresses lower four ribs, allowing diaphragm to act during inspiration

Innervation of Serratus Posterior Inferior
-intercostal nerves T9-T11
-subcostal nerve

Nuchal fascia
covers cervical region

Thoracolumbar Fascia
Covers thorax and lumbar regions

Attachments of Fascia
1. Superficial (posterior) lamina – attached medially to nuchal ligament, supraspinal ligament, tips of all spinous processes, and median crest of the sacrum
2. Deep (anterior) lamina – attached medially to base of skull below the superior nuchal line, to tips of cervical and lumbar transverse processes and to the angles of the ribs in the thoracic region
3. Laterally, both layers of the nuchal fascia blend and become continuous with the prevertebral fascia, and both layers of the thoracolumbar fascia become continuous with the fascias of teh anterolateral abdominal musculature

Origin of the Splenius Capitis et Cervicis
spinous prcesses of CV7-TV6

Insertion of Splenius Capitis
lateral portion of the superior nuchal line and mastoid process

Insertion of Splenius Cervicis
posterior tubercles of transverse processes of CV1-CV3

Action of Splenius Capitis
-extends head
-rotates and sidebends the head and neck to the same side

Action of the Splenius Cervicis
-extends and rotates neck to same side
-binds deeper musculature (means “bandage”)

Innervation of Splenius Capitis et Cervicis
dorsal rami of C2-C5

Erector Spinae
-occupies the vertebral-costal groove deep to the superficial and intermediate muscles of the back
-extends the full length of the vertebral column
-attaches via a strong aponeurotic tendon to iliac crest, sacrum, lumbar spinous processes and supraspinal ligament
-As it ascends, it separates into 3 portions: Iliocostalis, Longissimus, and Spinalis

Origin of Iliocostalis
-Crest of ilium and sacrum
-Posterior surface of ribs at angle

Insertion of Iliocostalis
-angle of ribs
-transverse processes of lower cervical vertebrae

Action of Iliocostalis
-extends vertebral column
-laterally flexes to same side

Innervation of Iliocostalis
dorsal rami of spinal nerves from vertebral segments covered by muscle

Iliocostalis
-lateral column of erector spinae
-divided into: lumborum, thoracis, and cervicis

Longissimus
-middle column of erector spinae
-divided into thoracis, cervicis, and capitis

Origin of Longissimus
transverse processes below

Insertion of Longissimus
-transverse processes above
-capitis portion: mastoid process, deep to splenius and sternocleidomastoid muscles

Action of Longissimus
-extends vertebral column
-lateral flexion to same side
-capitis portion: extends skull and rotates it to same side

Innervation of Longissimus
dorsal rami of spinal nerves from vertebral segments covered by muscle

Spinalis
-medial column of erector spinae
-divided into thoracis, cervicis and capitis
-capitis is usually blended with semispinalis capitis

Origin of Spinalis
spinous processes below

Insertion of Spinalis
spinous processes above

Action of Spinalis
-extends vertebral column
-lateral flexion to same side
-capitis portion: extends skull

Innervation of Spinalis
dorsal rami of spinal nerves from vertebral segments covered by muscle

Location of Transversospinal Group
-Deep to Erector Spinae group

Origin of Transversospinal Group
transverse processes below

Insertion of Transversospinal Group
spinous processes one to six segments above (depends on specific subdivision)

Action of Transversospinal Group
-one side acting:
-rotate vertebrae above to opposite
side
-sidebend vertebral column to same
side
-both sides acting simultaneously:
-extends vertebral column

Innervation of Transversospinal Group
dorsal rami of spinal nerves of vertebral segments covered by muscle

Semispinalis
-division of Transversospinal Group
-extends 1/2 of vertebral column: from lower thoracic to upper cervical levels – each subdivision spanning 4-6 vertebrae

Semispinalis Thoracis
continuous with the semispinalis cervicis

Semispinalis Cervicis
ends at spinous process of C2

Semispinalis Capitis
-largest muscle of posterior neck
-extends from mid thoracic and lower cervical vertebrae to the skull
-covers semispinalis cervicis
-fuses medially with spinalis capitis portion of erector spinae group

Multifidus
-Latin: “many segments”
-extends length of verteral column from sacrum to CV2
-each subdivision spans 2-4 vertebrae
-important in extension, slight rotatory component
-most important function: stabilizers between individual vertebrae

Rotatores
-extends length of vertebral column from sacrum to CV2
-each subdivision spans 1-2 vertbrae
-acts in extension and a little rotation
-most important function: stabilizers!!!

Intersegmental Deep Back Muscles
-deep to transversospinal muscles
-short muscles which span one vertebral segment
-function as stabilzers, not prime movers
-lots of stretch receptors – feedback on large postural muscles

Interspinales
-part of Intersegmental Deep Back Group
-paired muscles (left and right)
-span adjacent spinous processes of cervical and lumbar vertebrae
-innervated by dorsal rami of regional spinal nerves

Intertransversarii
-part of Intersegmental Deep Back Group
-paired muscles (anterior and posterior)
-span adjacent transverse processes of cervical and lumbar vertebrae

Innervation of Anterior Intertransversarii
ventral rami

Innervation of Posterior Intertransversarii
-lateral: ventral rami
-medial: dorsal rami

Levator Costarum
-the Lateral Posterior Intertransversarii in the Thoracic Region
-extend from transverse processes above to ribs (medial to angle) 1-2 segments below
-function: elevate the ribs
-Innervated by corresponding ventral rami of spinal nerves

Suboccipital Triangle and Assoc. Structures
-located deep to semispinalis capitis
-function to extend the skull and rotate the skull and atlas to same side
-ALL innervated by dorsal ramus of cervical spinal nerve C1 (suboccipital nerve)

Origin of Rectus Capitis Posterior Major
spinous process of CV2 (axis)

Insertion of Rectus Capitis Posterior Major
inferior nuchal line and occipital bone below

Action of Rectus Capitis Posterior Major
-extension and lateral flexion of the skull
-minimal rotation to same side

Innervation of Rectus Capitis Posterior Major
suboccipital nerve (C1 – dorsal ramus)

Origin of Rectus Capitis Posterior Minor
posterior tubercle of atlas (CV1)

Insertion of Rectus Capitis Posterior Minor
-medial portion of inferior nuchal line and occipital bone between inferior nuchal line and foramen magnum
-may attach to dura between C1 and occiput (has been implicated as a “probable” component of dural headaches)

Action of Rectus Capitis Posterior Minor
extension and some lateral flexion of skull

Innervation of Rectus Capitis Posterior Minor
suboccipital nerve (C1 – dorsal ramus)

Origin of Obliquus Capitis Inferior
spinous process of CV2 (atlas)

Insertion of Oliquus Capitis Inferior
transverse process of atlas (CV1)

Action of Oliquus Capitis Inferior
rotates skul and atlas on odontoid process to same side

Innervation of Obliquus Capitis Inferior
suboccipital nerve (C1 – dorsal ramus)

Origin of Oliquus Capitis Superior
transverse process of atlas (CV1)

Insertion of Oliquus Capitis Superior
occipital bone between superior and inferior nuchal lines

Action of Oliquus Capitis Superior
extends and sidebends skull to same side

Innervation of Obliquus Capitis Superior
suboccipital nerve (C1 – dorsal ramus)

Suboccipital Triangle Boundaries
-lateral superior: obliquus capitis superior
-lateral inferior: obliquus capitis inferior
-medial: rectus capitis posterior major
-roof: semispinalis capitis
-floor: posterior atlantooccipital membrane and posterior arch of atlas

Vertebral Artery
-in suboccipital triangle
-passes through transverse cervical foramen of atlas (through CV1-CV6)
-then turns medialward along groove in posterior arch of atlas and pierces posterior atlantooccipital membrane to get to foramen magnum

Suboccipital Nerve (C1 – Dorsal Ramus)
-pierces posterior atlantooccipital membrane between posterior arch of atlas and the vertebral artery
-then passes through triangle and distributes to ALL suboccipital muscles

Greater Occipital Nerve (C2 – Dorsal Ramus)
-emerges from beneath obliquus capitis inferior
-turns upward to cross same muscle and suboccipital triangle
-pierces semispinalis capitis and trapezius

Greater Occipital Nerve (C2 – Dorsal Ramus) Innervates?
-innervates posterior scalp as far forward as vertex of skull
-because it travels through semispinalis capitis, prolonged extension of the neck places continued traction on it, resulting in a tension headache with reference to its receptive field (occiput and vertex of skull)

Arteries of the Deep Back
-in general, muscles are supplied by vessels on REGIONAL BASIS
-via dorsal branches of specific arteries listed in Chapter 2 (pg. 23 of Buck Book)

Veins of Deep Back
-return from muscles of deep back is accomplished by venae cominantes of arterial supply
-tributaries to occipital, ascending cervical, vertebral, posterior intercostal, lumbar, iliolumbar and lateral sacral veins (serve as final common path of venous drainage for deep back muscles, spinal cord and vertebral column)
-most have continuity with vertebral venous plexus

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We use cookies to give you the best experience possible. By continuing we’ll assume you’re on board with our cookie policy TRAPEZIUS MUSCLE *Origin*: base of skull, spinous processes of cervical and thoracic vertebrae *Insertion*: Clavicle; acromion process and scapular …

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