Deep Back and Spinal Cord

identify muscles of the deep back

Erector Spinae

-Act on vertebre; both contract=extension spine, 1 side contract=lateral flexion

1. Spinalis

2. Longistimus

3. Iliocostalis

Deep to Erector Spinae

4. Multifidus

deep to multifi…

5. Rotatores

6. Levator Costareum

5 types of vertebrae

-7 cervical: neck

-12 thoracic: ribs

-5 lumbar

-(5) sacrum: fused, part of pelvis

-(4) coccyx: tail bone

parts of a typical vertebra

-Vertebral Body

-Transverse process

-Spinous process

-Superior and Inferior articular processes

• Superior and inferior vertebral notch: form the intervertebral foramen; where other vertebra articulate

-Vertebral foramen: spinal cord

Vertebral Arch (often where muscles attach)

-pedicle: between body and TP

-lamina: between TP and SP

foramens of vertebre

-intervertebral foramen: exit spinal nerves, R and L side

• formed by the inferior vertebral notch and superior vertebral notch

-vertebral foramen: spinal cord

label cervical vertebre

*unique in that it’s facet joints are more horizontal, and have traverse foramen w/ vertebral artery

what is the function of the transverse foramina?

has the vertebral artery

-branch from subclavial a

-to brain

atlas

First cervical vertebra (C 1)

-It has no body and leaves a space to accommodate the dens of the axis

-Superior articular surfaces articulate with occipital condyles(*articulates w/ skull)

-“YES” movement of the head

axis

Second cervical vertebra (C 2)

-It has a tooth-shaped process, the dens (odontoid process), which articulates with the atlas as a pivot joint

-“NO” movement of the head

__has a prominent spinous process

C7

*good for palpation

identify features of a thoracic vertebra

*articulates w/ ribs at costal facet and TP

*articular facets in coronal/vertical plane

*spinous process points inferiorly

identify features of a lumbar vertebra

*very large

*articular process in sagittal plane

*SP points post

sacrum and coccyx

-fused together; part of pelvis

Cervical vs. Thoracic vs. Lumbar Vertebrae

CERVICAL

-Transverse foramen

-Bifid spinous process (most of them)

-Articular facets oriented in transverse plane

THORACIC

-Costal facets (*ribs articulate)

-Articular facets oriented in coronal plane

-Spinous process directed inferiorly

LUMBAR

-Massive size (*large body, most weight bearing)

-Articular facets oriented in para-sagittal plane

-Spinous process directed posteriorly

intervertebral disc

-Annulus fibrosus: outer portion; composed of fibrocartilage and fibrous connective tissue

-Nucleus pulposus: inner portion; semigelatinous fluid with very few, if any, cells (*squisher, gel-like)

• Note: NO intervertebral disc between atlas and axis (C1 and C2)

-The IV disc is reinforced anteriorly AND anterolaterally by the anterior longitudinal ligament.

-The IV disc is reinforced posteriorly by the posterior longitudinal ligament.

• The IV disc is not reinforced posterolaterally.

“Wiplash injury”

-Results from severe hyperextension of the neck, as occurs in during rear-end motor vehicle collisions, especially when the head restraint is too low

-Anterior longitudinal ligament is severely stretched and may be torn

-May injure posterior parts of the vertebral arches and their processes

-Herniation of the nucleus pulposus is almost always in a ___direction

-Practice Question: A 70-year-old female complaining of lower back pain is diagnosed with a herniated disc at the level of L4-5.  Which spinal nerve(s) is/are most likely compressed?

-Herniation of the nucleus pulposus is almost always in a
posterolateral direction, passing through a rupture of the annulus fibrosus.

• may lean to opposite side to relieve compression of nerve; IVD impinge on SN

Practice Question

-L5

Articular facets (zygopophyses)

joints of C1 and C2

ligaments of C1 and C2

-Alarl l and Cruciate l: support movements of C2

Cruciate l

Made from

-Transverse l of atlas

-Sup and inf longitudinal brands

ligaments of intervertebral joints

-Ligamentum flavum: spans the space between laminae/arches, yellowish color

-Interspinous ligament: between SP

-Supraspinous ligament: spans between post end SP

-Ligamentum nuchae (nuchal ligament): nuchal line cranium → SP cervical vertebra, sagittal articulations, origin trapezius

-Intertransverse ligaments

movements of vertebral column

*extension=erector spinae

*flexion=abs

*lateral flexion=erector spinae unilaterally

range of motion in vertebral joints

-atlanto-occipital: not lot rotation

-altanto-axial: most rotation

-other 3: rotation w/ horizontal plane; lumbar not lot bc peri-sagittal orientation

*don’t have to memorize numbers!

normal curvatures of the vertebral column

-fetus: not lot curves

-4 years old: L and S curves when start to walk

-Lumbar lordosis

abnormal curvatures of the vertebral column

-Kyphosis: excessive convexity of thoracic region

-Scoliosis: abnormal lateral curvature

*^often accompany each other

-(Hyper)lordosis AKA “pelvic tilt”: increased lordotic curve, if pregnant or obese

meninges of spinal cord

*dura matter=outer layers (this picture)

*+subarahnoid space w/ CSF deep to dura matter and arachnoid; and epidural space superficial to dura matter

Spinal cord changes diameter

-Which spinal cord levels contribute to the cervical enlargement of the spinal cord?

-Which spinal cord levels contribute to the lumbar enlargement of the spinal cord?

-C5-T1

-T11-S2

end of the spinal cord

~L1/2

-Conus medularis: end point spinal cord

-Cauda Equina=”horses tail”

-Filum terminale: made from pia mater, anchors SC in spinal canal to coccyxx

features of a spinal cord

-Dorsal horn: conveys presynaptic general sensory fibers

-Ventral horn: location of somatic motor cell bodies

-Lateral horn (located T1-L2 and S2-4 only): location of cell bodies of presynaptic sympathetic neurons

-Dorsal nerve root: conveys sensory fibers

-Ventral nerve root: conveys motor fibers from the ventral horn

-Dorsal root ganglion: location of sensory cell bodies

-Spinal nerve: location of both sensory AND motor fibers

-Dorsal rami: convey motor AND sensory innervation to the back (*innervate segmentally; intrinsic back muscels)

-Ventral rami: convey motor AND sensory innervation to the rest of the trunk and the limbs (*brachial and lumbarsacral plexus)

• Dorsal horn (sensory) → dorsal rootlets → dorsal root → dorsal root ganglion → spinal nerve

• Ventral horn (motor) → ventral rootlets → ventral root → spinal nerve

-Gray matter: where cell bodies live

-White matter: end of nerve cells

dermatomes of the back

-relate to dorsal rami; close to where spinal nerves emerge from vertebre

-chest/back: sequential; bc how developed as embryo

-legs: extrude from trunk and rotated relative to forearm

suboccipital triangle

-borders: rectus posterior capitis Major + obliquus capitis superior + obliquus capitis inferior

-contents: vertebral a, suboccipital n (C1)

• greater occipital n (C2): inferior to triangle, mostly sensory back of head

deep neck muscles

-what are they (list their names)

-what are they innervated by

-what do they do

-Rectus capitis posterior major; Rectus capiti posterior minor; obliquus capitis superior; obliquus capitis inferior

-Suboccipital n

-Extend head and proprioception (=convey signals where body is in space; vision and postures issues if too tight!)

• Obliquus also Laterally Flex head

*Dr. K story: altereted posture form her long-covid effected her suboccipital muscles (too tight or stretched out)

Possible sources of back pain

Superficial back

-Tension in upper trapezius

-Tension in levator scapulae!

-Weak rhomboids relative to pecs lead to slouching (and vice versa; *stretched out rhomboids relative to pecs)

Neck

-Tight scalenes (neck muscles) compress the dorsal scapular n. (*passes through them)

-Back pain/pain along C5 dermatome (*and pathway nerve itself)

Posterior Abdominal Wall

-Tension in postural muscles like quadratus lumborum (posterior abdominal wall) and psoas major

• Note their attachments to lumbar vertebrae (*originate from LV; too tight)

possible sources of spinal nerve compression causing pain and/or paraesthesia + where most common

-Herniated intervertebral disc

-Narrowing of spinal canal (stenosis)

-Bony impingement caused by arthritis

-Scoliosis and other spinal variations

-Can affect limbs!: Most common in lumbar region (also cervical)

*affect fem and obturator n; usually lumbar and thoracic region and less in cervical

muscles of the deep back: superifical → intermediate → deep → minor deep layer

1.Superficial Layer

a.Splenius

2.Intermediate Layer

a.Erector spinae (Sacrospinalis): Iliocostalis, Longissimus, Spinalis

3.Deep Layer

a.  Transversospinalis: Semispinalis, Multifidus, Rotatores 

4.Minor Deep Layer

a.Interspinales

b.Intertransversarii

c.Levatores costarum

action muscles of the deep back: superficial layer

Semispinalis capitis + Splenius capitis

-acting bilaterally: extends head and neck, proprioception

-acting unilaterally: laterally flexes neck and rotates head to side of active muscles

action muscles of the deep back: intermediate layer

erector spinae (*deep SA) + serratus posterior superior and inferior (*more proprioceptive in function)

ERECTOR SPINAE

-acting bilaterally: extends vertebral column and head

-acting unilaterally: laterally flexes vertebral column

action muscles of the deep back: transversospinalis

-SEMISPINALIS: extends head and neck/cervical regions, priprioception (bilaterally); and rotates them contralaterally (unilateral)

-ROTATORES: stabilize vertebrae, and assist in local extension and rotatory movements

 -MULTIFIDUS: stabilizes vertebrae during local movements

actions muscles of the deep back: minor deep layer

-INTERSPINALES: stabilize vertebre; aid in extension and rotation of vertebral column

-LEVATORES COSTARUM: elevate ribs; aid in lateral flexion of vertebral column

-INTERTRANSVERSARII: stabilize vertebral column bilaterally; aid in lateral flexion of vertebral column

muscle table: erector spinae

Key Points

-ext back bi; LF uni

-DR C3-L5

muscle table: transversospinal muscles

Key Points

-DR

-Actions:

• Multifidi: stabilize

• Rotatores: stabilize, assist extension and roation

• Semispinalis: ext head and neck and proprioceptio (bi); contralteral rotation (uni)

• Levator Costarum: elevates ribs, aid in LF

muscle tabel: short segmental muscles

Key Ponts

-DR

-both stabilize vertebre

• IT: aid LF

• IS: aid ext and rotation