Muscles of the Back
levatores costarum- origin
Origin: tips of transverse processes from C7 to T11
Obliquus Capitis Superior
Origin: transverse process of atlas (C1) Insertion: occipital bone (lateral part of area between superior and inferior nuchal lines) Nerve supply: suboccipital nerve Action: extension of head lateral flexion of head to same side of contracting muscle
Levator scapulae origin
Origin: transverse processes of upper 4 cervical vertebrae
what are other mm that are associated with the spine? slide 32
intertransversarii: extend between adjacent transverse processes best developed in cervical and lumbar regions interspinales: extend between adjacent spinous processes best developed in cervical and lumbar regions -levatores costarum
Semispinalis- location SLIDE 25-26
lacking below thoracic region has thoracis, cervicis and capitis subdivisions
Describe Transversospinalis
muscle fibers run superiorly and medially from transverse processes to spinous processes depending on length of muscle fibers, it is divided into 3 components (longest muscle fibers are more superficial within transversospinalis, shorter muscle fibers are deeper):
Multifidus-LOCATION
present along whole length of spine in sacral and lumbar regions lies deep to erector spinae (because there is no semispinalis in these areas) in thoracic and cervical regions it lies deep to semispinalis fibers insert into spinous processes of all vertebrae from L5-axis best developed in lumbar region
Other Muscles Associated with the Spine suboccipital muscles: describe
4 short muscles attaching to occipital bone, atlas and axis deepest muscles in upper part of posterior neck (lie deep to trapezius, splenius capitis and semispinalis capitis) components: rectus capitis posterior major rectus capitis posterior minor obliquus capitis inferior obliquus capitis superior all 4 muscles are supplied by suboccipital nerve (dorsal ramus of C1 spinal nerve)
What is the action of splenius capitis and splenius cervicis? slide 19
Action (both muscles): bilateral contraction > extension of head and neck, unilateral contraction > lateral flexion and rotation of head and neck to same side of contracting muscle
what is the action of the trapezius mm? refer to slide 6-7
Action: helps stabilize scapula upper fibers elevate scapula middle fibers pull scapula toward posterior midline (retract) lower fibers depress scapula acting together, superior and inferior fibers rotate scapula superiorly (inferior angle moves up and laterally) important movement in order to perform full abduction of arm (bring hand above head)
latissimus dorsi action
Action: extension, adduction and medial rotation of arm at shoulder joint when arms are raised above head, it pulls trunk upward
levator scapulae action
Action: helps stabilize scapula elevation of scapula inferior rotation of scapula
levatores costarum- insertion
Insertion: fibers run inferiorly and laterally and insert into rib immediately below (levator costarum brevis) or 2nd rib below (levator costarum longus)
serratus posterior superior insertion
Insertion: fibers run inferolaterally insert into 2nd to 5th ribs
Trapezius insertion
Insertion: lateral ⅓ of clavicle, acromion and spine of scapula
levator scapulae insertion
Insertion: medial border of scapula (above root of spine)
rhomboid minor insertion
Insertion: medial border of scapula (at level of root of spine)
rhomboid major insertion
Insertion: medial border of scapula (below root of spine)
Latissimus Dorsi insertion
Insertion: muscles fibers pass superiorly and laterally wrap around inferior border of teres major muscle tendon inserts into floor of intertubercular (bicipital) groove of humerus
serratus posterior superior nerve supply and action
Nerve supply: 2nd to 5th intercostal nerves (ventral rami of T2 to T5 spinal nerves) Action: elevation of ribs
nerve supply of erctor spinae slide 21
Nerve supply: dorsal rami of spinal nerves Action: bilateral contraction > extension of spine unilateral contraction > lateral flexion of spine to same side of contracting muscle
levatores costarum: nerve supply and action slide 34
Nerve supply: dorsal rami of spinal nerves Action: elevation of ribs lateral flexion of spine
what is the rhomboids nerve supply and action?
Nerve supply: dorsal scapular nerve (branch of brachial plexus) Action: help stabilize scapula, retraction of scapula, inferior rotation of scapula
latissimus dorsi nerve supply
Nerve supply: thoracodorsal nerve (branch of brachial plexus)
levator scapulae nerve supply
Nerve supply: ventral rami of C3 and C4 spinal nerves and dorsal scapular nerve (branch of brachial plexus)
Rectus Capitis Posterior Major: origin, insertion, nerve supply, action
Origin: spinous process of axis (C2) Insertion: lateral part of inferior nuchal line Nerve supply: suboccipital nerve Action: extension of head rotation of head to same side of contracting muscle
rhomboid minor origin slide 13
Origin: lower part of ligamentum nuchae and spinous processes of C7 and T1
splenius capitis origin
Origin: lower part of ligamentum nuchae and spinous processes of C7 to T3 vertebrae
Obliquus Capitis Inferior: location , origin, insertion, nerve supply, action
Origin: spinous process of axis (C2) Insertion: transverse process of atlas (C1) Nerve supply: suboccipital nerve Action: rotation of head to same side of contracting muscle
rhomboid major origin
Origin: spinous processes from T2 to T5
Trapezius origin
Origin: medial part of superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes (C7 to T12)
serratus posterior superior origin slide 16
Origin: lower part of ligamentum nuchae and spinous process of C7 to T2 or T3
Rotatores- slide 29-30
deepest muscles located in groove between spinous and transverse processes best developed in thoracic region extend from a transverse process to spinous process of vertebra located immediately above (rotator brevis) or to spinous process of 2nd vertebra above (rotator longus
what is the nerve supply and action of transversospinalis?
dorsal rami of spinal nerves Action: bilateral contraction > extension of spine unilateral contraction: lateral flexion of spine to same side of contracting muscle rotation of spine to opposite side of contracting muscle shorter muscles main function is to stabilize vertebral column
Greater Occipital nerve slides 42-43
dorsal ramus of C2 spinal nerve curves around inferior border of obliquus capitis inferior ascends superficial to suboccipital triangle pierces semispinalis capitis and trapezius to reach scalp (does not pierce splenius capitis) divides into branches that supply skin of posterior part of scalp (run with branches of occipital artery)
serratus posterior inferior insertion
fibers run superolaterally > insert into lower 4 ribs
splenius capitis insertion
fibers run superolaterally and insert into lateral part of superior nuchal line (occipital bone) and mastoid process (temporal bone)
what innervates the deep mm of the back?
innervated by dorsal rami of spinal nerves
Semispinalis Capitis- Location KNOW IN DETAIL
large muscle on back of neck originates from transverse processes of T1 to T6 vertebrae and articular processes of lower 3 or 4 cervical vertebrae muscle fibers ascend deep to splenius and insert into occipital bone, in medial part of area between superior and inferior nuchal lines Action extend head and neck and rotate to opposite side
Suboccipital Triangle boundaries: laterally
laterally: obliquus capitis superior
Suboccipital Triangle boundaries: medially
medially: rectus capitis posterior major
name the 3 components of transversospinalis
semispinalis: muscle fibers span 6 or more vertebrae between origin and insertion multifidus: muscle fibers span 3 to 5 vertebrae between origin and insertion rotatores: muscle fibers span 1 or 2 vertebrae between origin and insertion
Name the two intermediate mm of the back
serratus posterior superior serratus posterior inferior
serratus posterior inferior origin
spinous processes from T11 to L2 or L3
muscles are divided into 3 groups, what are they?
superficial group: muscles insert into bones of upper limb (clavicle, scapula, humerus) intermediate group: muscles insert into ribs (accessory muscles of respiration) deep group: muscles involved with movements of vertebral column and head (proper/intrinsic muscles of back)
Name the 4 superficial mm of the back
superficial muscles: trapezius latissimus dorsi levator scapulae rhomboid minor and major
serratus posterior inferior nerve supply and action
Nerve supply: 9th, 10th, 11th intercostal nerves and subcostal nerve (ventral rami of T9 to T12 spinal nerves) Action: depression of ribs
Trapezius nerve supply
Nerve supply: accessory nerve (CN XI) and ventral rami of C3 and C4 spinal nerves latter nerves probably provide sensory innervation (proprioception)
Splenius Cervicis origin and insertion
Origin: spinous processes of T3 to T6 vertebrae Insertion: fibers run superolaterally and insert into transverse processes of upper 3 to 4 cervical vertebrae
Latissimus Dorsi origin slides 9-10
Origin: spinous processes of lower 6 thoracic, lumbar and sacral vertebrae, posterior part of iliac crest, lower 3 or 4 ribs, and sometimes inferior angle of scapula (attachments to vertebrae and iliac crest are established via thoracolumbar fascia)
Suboccipital Triangle boundaries :Inferiorly and what are the contents of the Suboccipital Triangle
inferiorly: obliquus capitis inferior covered by semispinalis capitis (roof) floor: posterior arch of atlas and posterior atlanto-occipital membrane contents: vertebral artery (3rd part) and suboccipital nerve (nerve emerges between vertebral artery and posterior arch of atlas)
Erector Spinae large muscular mass with an extensive inferior tendinous origin (erector spinae aponeurosis) Name the 3 columns they are divided into
lateral column: iliocostalis intermediate column: longissimus (largest component) medial column: spinalis (smallest component)
location of serratus posterior inferior
lies deep to latissimus dorsi
location of serratus posterior superior
lies deep to rhomboid mm
Rectus Capitis Posterior Minor location , origin, insertion, nerve supply, action
located medial and partly under rectus capitis posterior major Origin: posterior tubercle of atlas (C1) Insertion: medial part of inferior nuchal line Nerve supply: suboccipital nerve Action: extension of head
name the 3 groups the deep mm divide into: hint: superficial layer intermediate layer deep layer
superficial layer: only present in cervical and upper thoracic regions consists of SPLENIUS CAPITUS and SPLENIUS CERVICISmuscles fibers run superiorly and laterally intermediate layer: extends whole length of spine formed by ERECTOR SPINAE muscle fibers are more or less vertically oriented deep layer: extends whole length of spine formed by TRANSVERSOSPINALIS muscle fibers run superiorly and medially