Muscles of the Back
What are the three component of transversospinalis? (deep layer of the deep muscles)
-Semispinalis: muscle fibers span 5 or more vertebrae between origin and insertion -Multifidus: muscle fibers span 3 or 4 vertebrae between origin and insertion -Rotatores: muscle fibers span 1 or 2 vertebrae between origin and insertion
What is the origin of the splenius cervicis? (superficial layer of the deep muscles)
Origin: spinous processes of T3 to T6 vertebrae
What is the origin of the Latissimus Dorsi?
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)
What is the origin of the levatores costarum?
Origin: tips of transverse processes from C7 to T11
What is the origin of Obliquus Capitis superior?
Origin: transverse process of atlas (C1)
What is the origin of the levator scapulae?
Origin: transverse processes of upper 4 cervical vertebrae
What is the nerve that supplies the four muscles of the suboccipital muscles?
Suboccipital nerve (dorsal ramus of C1 spinal nerve)
What are the three groups of back muscles?
Superficial, Intermediate, Deep
What are the three layers of the deep back muscles?
Superficial, intermediate, deep
What is the origin of Obliquus capitis inferior?
Origin: spinous process of axis (C2)
What is the origin of rectus major?
Origin: spinous process of axis (C2)
What are the suboccipital muscles?
-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) -Four components (muscles)
What is the erector spinae muscle (intermediate layer of the deep muscles) and how does it divide into three columns?
-Erector spinae muscle is a large muscular mass with an extensive inferior tendinous origin (erector spinae aponeurosis) -The muscle is divide into 3 columns: lateral, intermediate, and medial
What are the muscles of each column of the erector spinae? (intermediate layer of the deep muscles)
-Lateral column: iliocostalis -Intermediate column: longissimus (largest component) -Medial column: spinalis (smallest component)
Where is the rotatores located? (where is it best developed)
-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 greater occipital nerve and where does it go?
-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)
Where is the interspinales muscle?
-extend between adjacent spinous processes -best developed in cervical and lumbar regions
Where is the intertransversarii muscle?
-extend between adjacent transverse processes -best developed in cervical and lumbar regions
What are the actions of the latissimus dorsi?
-extension, adduction and medial rotation of arm at shoulder joint -when arms are raised above head, it pulls trunk upward
What are the actions of the levator scapulae?
-helps stabilize scapula -elevation of scapula
What are the actions of the trapezius?
-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 at shoulder joint (bring hand above head)
Where is the semispinalis muscle not located, and what types of subdivisions does it have?
-lacking below thoracic region -has thoracis, cervicis and capitis subdivisions
Where does the subdivision: semispinalis capitis, originate and insert?
-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
What is the transversospinalis muscle (deep layer of the deep muscles) and how is it divided?
-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)
Where is the multifidus muscle located? (what does it lay deep to, where does it insert, where is it best developed)
-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
What are the four components (muscles) of the suboccipital muscles?
-rectus capitis posterior major (rectus major) -rectus capitis posterior minor (rectus minor) -obliquus capitis inferior (inferior oblique) -obliquus capitis superior (superior oblique)
What are the boundaries of the suboccipital triangle? (contents)
3 Boundaries: -medially: rectus capitis posterior major -laterally: obliquus capitis superior -inferiorly: obliquus capitis inferior -Covered by semispinalis capitis (roof of triangle) -Floor of triangle: posterior arch of atlas and posterior atlanto-occipital membrane -Contents of triangle: vertebral artery (3rd part) and suboccipital nerve (nerve emerges between vertebral artery and posterior arch of atlas)
What are the actions of the splenius cervicis? (superficial layer of the deep muscles)
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 are the actions of the rhomboid muscles?
Action (both muscles): help stabilize scapula, retraction of scapula
What are the actions of the transversospinalis? (deep layer of the deep muscles)
Action: -bilateral contraction: extension of spine -unilateral contraction: lateral flexion of spine to same side of contracting muscle and rotation of spine to opposite side of contracting muscle -shorter muscles main function is to stabilize vertebral column
What are the actions of Obliquus Capitis superior?
Action: -extension of head -lateral flexion of head to same side of contracting muscle
What are the actions of rectus major?
Action: -extension of head -rotation of head to same side of contracting muscle
What is the action of the levatores costarum?
Action: Elevation of ribs
What are the actions of the erector spinae? (intermediate layer of the deep muscles)
Action: bilateral contraction, extension of spine, unilateral contraction, lateral flexion of spine to same side of contracting muscle
What is the action of the serratus posterior inferior?
Action: depression of ribs
What is the action of the serratus posterior superior?
Action: elevation of ribs
What is the action of rectus minor?
Action: extension of head
What is the action of Obliquus capitis inferior?
Action: rotation of head to same side of contracting muscle
What is the muscle of the intermediate layer of the deep back muscles?
Erector spinae muscle
What are the deep back muscles innervated by?
Innervated by dorsal rami of spinal nerves
What is the insertion of the levatores costarum?
Insertion: fibers run inferiorly and laterally and insert into rib immediately below (levator costarum brevis) or 2nd rib below (levator costarum longus)
What is the insertion of serratus posterior superior?
Insertion: fibers run inferolaterally insert into 2nd to 5th ribs
What is the insertion of the splenius capitis? (superficial layer of the deep muscles)
Insertion: fibers run superolaterally and insert into lateral part of superior nuchal line (occipital bone) and mastoid process (temporal bone)
What is the insertion of the splenius cervicis? (superficial layer of the deep muscles)
Insertion: fibers run superolaterally and insert into transverse processes of upper 3 to 4 cervical vertebrae
What is the insertion of the serratus posterior inferior?
Insertion: fibers run superolaterally insert into lower 4 ribs
What is the insertion of rectus major?
Insertion: lateral part of inferior nuchal line
What is the insertion of the trapezius?
Insertion: lateral ⅓ of clavicle, acromion and spine of scapula
What is the insertion of the levator scapulae?
Insertion: medial border of scapula (above root of spine)
What is the insertion of the rhomboid minor?
Insertion: medial border of scapula (at level of root of spine)
What is the insertion of rhomboid major?
Insertion: medial border of scapula (below root of spine)
What is the insertion of rectus minor?
Insertion: medial part of inferior nuchal line
What is the insertion of the latissimus dorsi?
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
What is the insertion of Obliquus Capitis superior?
Insertion: occipital bone (lateral part of area between superior and inferior nuchal lines)
What is the insertion of Obliquus capitis inferior?
Insertion: transverse process of atlas (C1)
What are the other muscles associated with the spine?
Intertransversarii, Interspinales, Levatores costarum, Suboccipital muscles
Where is the rectus minor located?
Located medial and partly under rectus capitis posterior major
What is the nerve supply of transversospinalis? (deep layer of the deep muscles)
Nerve supply: dorsal rami of spinal nerves
What is the nerve supply of the splenius cervicis? (superficial layer of the deep muscles)
Nerve supply (both muscles): dorsal rami of spinal nerves
What is the nerve supply for the rhomboid muscles?
Nerve supply (both muscles): dorsal scapular nerve (branch of brachial plexus)
What is the nerve supply of serratus posterior superior?
Nerve supply: 2nd to 5th intercostal nerves (ventral rami of T2 to T5 spinal nerves)
What is the nerve supply of the serratus posterior inferior?
Nerve supply: 9th, 10th, 11th intercostal nerves and subcostal nerve (ventral rami of T9 to T12 spinal nerves)
What nerve supplies the trapezius?
Nerve supply: accessory nerve (CN XI) and ventral rami of C3 and C4 spinal nerves last 2 nerves probably provide sensory innervation (proprioception)
What is the nerve supply of the erector spinae? (intermediate layer of the deep muscles)
Nerve supply: dorsal rami of spinal nerves
What is the nerve supply of the levatores costarum?
Nerve supply: dorsal rami of spinal nerves
What is the nerve supply of Obliquus Capitis superior?
Nerve supply: suboccipital nerve
What is the nerve supply of Obliquus capitis inferior?
Nerve supply: suboccipital nerve
What is the nerve supply of rectus major?
Nerve supply: suboccipital nerve
What is the nerve supply of rectus minor?
Nerve supply: suboccipital nerve
What is the nerve supply of the latissimus dorsi?
Nerve supply: thoracodorsal nerve (branch of brachial plexus)
What is the nerve supply of the levator scapulae?
Nerve supply: ventral rami of C3 and C4 spinal nerves and dorsal scapular nerve (branch of brachial plexus)
What is the origin of the splenius capitis? (superficial layer of the deep muscles)
Origin: lower part of ligamentum nuchae and spinous processes of C7 to T3 vertebrae
What is the origin of the serratus posterior inferior?
Origin: spinous processes from T11 to L2 or L3
What is the origin of rhomboid major?
Origin: spinous processes from T2 to T5
What is the origin of the trapezius?
Origin: medial part of superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes (C7 to T12)
What is the origin of rectus minor?
Origin: posterior tubercle of atlas (C1)
What is the origin of the Serratus posterior superior?
Origin: lower part of ligamentum nuchae and spinous process of C7 to T2 or T3
What is the origin of the rhomboid minor?
Origin: lower part of ligamentum nuchae and spinous processes of C7 and T1
What are the two muscles of the intermediate back?
Serratus posterior superior and Serratus posterior inferior
What are the two muscles of the superficial layer of the deep back muscles?
Splenius capitis and splenius cervicis
What is the muscle of the deep layer of the deep back muscles?
Transversospinalis muscle
What are the four superficial muscles?
Trapezius, Latissimus dorsi, Levator scapulae, Rhomboid minor and major
What does the Serratus posterior inferior lay deep to?
lies deep to latissimus dorsi
What does the Serratus posterior superior lay deep to?
lies deep to rhomboid muscles
