Transition Zones/Myology of the Back Flashcards
What is the incidence of lumbar ribs in the population?
Over 7% of the population demonstrates lumbar ribs
What is characteristic of lumbarization of S1?
The failure of synostosis between S1 and S2, squaring of the vertebral body of S1 and flaring of the sacral ala
What is the incidence of sacralization of L5 in the population?
41%-85%
Which segment demonstrates the greatest morphological variation along the spine?
L5
What is the incidence of variation within the sacrococcygeal region in the population?
Up to 14%
The trapezius is innervated by what nerve?
Spinal accessory nerve
What forms the spinal accessory nerve innervating the trapezius?
C1-C5 cord levels contribute to the spinal root of the spinal accessory nerve
Which of the muscles of the true back is innervated by the thoracodorsal nerve?
Latissimus dorsi
What forms the thoracodorsal nerve innervating the lattisimus dorsi?
Ventral rami from C6-C8
Which of the muscles of the true back are innervated by the dorsal scapular nerve?
Levator scapulae, rhomboid major, rhomboid minor
What forms the dorsal scapular nerve?
The ventral ramus of C5
What muscles lie just beneath the trapezius in the neck?
Spenius capitis and splenius cervicis
What does the word “splenius” mean?
It is the Greek word for bandage
What is the innervation of the splenius capitis?
Dorsal rami of middle cervical spinal nerves (C3-C5 cord levels)
What is the innervation of the splenius cervicis?
Dorsal rami of lower cervical spinal nerves (C5-C7 cord levels)
Which muscles are identified as erector spinae or sacrospinalis muscles?
Iliocostalis, longissimus, spinalis
What is the innervation of the iliocostalis lumborum?
Dorsal rami of lower thoracic and all lumbar spinal nerves
Which subdivision of the iliocostalis primarily originates and inserts on ribs?
Iliocostalis thoracis
What is the innervation of the iliocostalis thoracis?
Dorsal rami of upper 6 thoracic spinal nerves (T1-T6 cord levels)
What is the insertion for the iliocostalis cervicis?
Posterior tubercle of transverse process of C(3) C4-C6
What is the innervation of the iliocostalis cervicis?
Dorsal rami of T1, T2 spinal nerves, sometimes C8 spinal nerve (C8, T1, T2 cord levels)
Which erector spinae muscle is attached to the accessory process?
Longissimus thoracis
What is the innervation of the longissimus thoracis?
Dorsal rami of all thoracic & lumbar spinal nerves (cord levels T1-T12, L1-L5)
What is the innervation of the longissimus cervicis?
Dorsal rami of C4-C8 and T1-T2 spinal nerves (C4-C8 & T1-T2 cord levels)
What is the innervation of the longissimus capitis?
Dorsal rami of C1-C3 or C4 spinal nerves, (C1-C3 or C4 cord levels)
Which erector spinae muscles attach to cervical articular processes?
Longissimus cervicis & longissimus capitis
What osseous parts of the vertebral column serve as an origin to the spinalis thoracis?
Spinous processes of T11 & T12-L1 & L2
What is the innervation of the spinalis thoracis?
Dorsal rami of all thoracic & upper lumbar spinal nerves
What is the innervation of the spinalis cervicis?
Dorsal rami of all cervical spinal nerves (C1-C8 cord levels)
What is the innervation of the spinalis capitis?
Dorsal rami of lower cervical & upper thoracic spinal nerves
Which muscles are identified as transversospinalis muscles?
Semispinalis, multifidis, and rotators
How many vertebrae can be attached to a single segment by transversospinalis muscles?
As many as nine vertebrae
Contraction of semispinalis thoracis will result in what movements?
Extension, lateral flexion & rotation of upper thoracic and lower cervical spine, bilaterally they act to extend the thoracic spine
What is the innervation of the semispinalis thoracis?
Dorsal rami of T1-T6 spinal nerves (cord levels T1-T6)
What is the innervation of the semispinalis cervicis?
Dorsal rami of C6-C8 spinal nerves (cord levels C6-C8)
What is the innervation of the semispinalis capitis?
Dorsal rami of C1-C6 spinal nerves (cord levels C1-C6)
The semispinalis capitis and spinalis capitis may fuse to form what muscle?
Biventer cervicis
What osseous parts of the vertebral column serve as an origin to the classic multifidis?
Articular process of C4-C7, transverse processes of T1-T12, mammillary processes of L1-L5, and the dorsal surface of S1-S4 or S5
Which transversospinalis muscle attaches to articular and mammillary processes along the spine?
Multifidis
Contraction of the classic multifidis will result in what movements of the vertebral column?
Lateral flexion & rotation of the spine, maintains the lumbar lordotic curve, and prevents entrapment of zygapophyseal capsular ligament during movement
Which muscles of the spine exhibit a reversal of the expected origin-insertion combination?
Iliocostalis lumborum pars lumborum, longissimus thoracis pars lumborum, and multifidis lumborum
Rotator muscles are typically identified in what region of the spine?
The thoracic region
What muscles are included in the suboccipital muscle group?
Rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis inferior, and obliquus capitis superior
Which suboccipital muscle lacks an attachment to the skull?
Obliquus capitis inferior
Which nerve will innervate all suboccipital muscles?
The dorsal ramus of C1, the suboccipital nerve
What is the proposed function of the suboccipital muscle group?
Postural stabilizers of the atlanto-occipital and atlanto-axial joints
Which suboccipital muscles are known to attach to dura mater?
Rectus capitis posterior major, rectus capitis posterior minor, and obliquus capitis inferior
At what locations will interspinalis be absent along the spine?
T3-4 down to T10-T11
Based on the density of muscle spindles, what is the proposed function of the interspinalis?
Acts as a proprioceptive transducer in conjunction with intertransversarii to coordinate the smooth movement of the spine and to maintain appropriate posture
Which muscle group is innervated by both dorsal rami and ventral rami of spinal nerves?
Intertransversarii
Based on the density of muscle spindles, what is the proposed function of the intertransversarii?
Acts as a proprioceptive transducer in conjunction with interspinalis to coordinate the smooth movement of the spine and to maintain appropriate posture
What is the origin of the longus colli?
Vertebral bodies of C5-C6, T1-T3 & anterior tubercles of transverse processes C3-C5
What is the origin of the longus capitis?
Anterior tubercles of transverse processes C3-C6
What is the origin of the rectus capitis anterior?
Lateral mass & costal element of the transverse process of C1
What is the insertion of the middle scalene?
Between the tubercle and groove for the subclavian artery on the first rib
What is the insertion of the posterior scalene?
Outer surface of second rib
The quadratus lumborum is implicated in the formation of which ligament?
The iliolumbar ligament
What is the origin of the psoas major?
Vertebral bodies T12, L1-L5, S1, and transverse processes of L1-L5
What is the origin of psoas minor?
Vertebral bodies T12, L1
What will innervate the levator costarum brevis?
The dorsal rami of T1-T12 spinal nerves
What will innervate the levator costarum longus?
The dorsal rami of the lower thoracic spinal nerves