Vertebral Column, Spinal Cord and Back

Question 1

Describe and state the function of the Vertebral Column

Answer 1

1. Extends from the cranium to the apex of the coccyx
2. Main part of the axial skeleton
   - -articulated bones of the cranium, vertebral column, ribs and sternum
3. Protects the spinal cord and spinal nerves
4. Supports weight of the upper body
5. Partly rigid and flexible=> posture and locomotion
6. Presacral vertebral column is flexible in part to intervertebral discs
7. 33 total vertebrae

Question 2

Where are the Curvatures of the Vertebral Column

Answer 2

Four curvatures provide additional flexibility
Cervical curvature concave posteriorly (natural lordosis)
Thoracic curvature concave anteriorly (natural kyphosis)
Lumbar curvature concave posteriorly (natural lordosis)
Sacral curvature concave anteriorly (natural kyphosis)
Not as profound in females so that the coccyx protrudes less into the pelvic outlet (birth canal)
“High” Curves C5, L3
“Low” Curves T5, S2

Question 3

Abnormal Curvatures

Answer 3

1. Excessive thoracic kyphosis
   Erosion and collapse of vertebrae- osteoporosis
2. Excessive lumbar lordosis
   Weakened trunk musculature
   Temporary in late pregnancy
3. Scoliosis
   Abnormal lateral curvature with rotation of the vertebrae
   Asymmetric weakness of intrinsic back muscles, failure of half of the vertebra to develop or difference in lower limb length

Question 4

Describe the Vertebrae Structure and Function

PLVV

Answer 4

Vary in size and structure from one region to another
1.Vertebral body:
Strengthen vertebral column
Increases as move inferiorly
2. Vertebral arch:
Formed by the pedicles and laminae
3. Pedicles (2):
Short processes that join vertebral arch to vertebral body
4. Laminae (2):
Join with pedicles and meet in the midline to complete arch

Question 5

Describe the Vertebrae Structure and Function

Hint: VAST

Answer 5

1. Vertebral foramen:
   Formed by the arch and body
   Provides passage way for spinal cord, meninges, fat, spinal nerve roots and vessels
2. Articulating facets (2 superior and 2 inferior):
   With adjacent vertebrae form the Intervertebral Foramina which give passage to spinal nerve roots and vessels
3. Spinous process:
   Projects posteriorly
   Provides attachment for deep back muscles
4. Transverse process (2):
   Projects posterolateral
   Provides attachment for deep back muscles

Question 6

Describe the Cervical Vertebrae (7)

Answer 6

1. Small body
2. Large vertebral foramen
3. Transverse processes contain foramen (foramina transversarium) which allow vertebral arteries, vertebral veins and sympathetic plexuses to pass
   - Absent in C7
4. Spinous process of C3-C5 short and bifid
5. Spinous process of C7 is long- vertebra prominens

Question 7

Atlas (C1) and Axis (C2)

Answer 7

1. Atlas (C1)
   Ring-like
   No spinous process or body
   Two lateral masses connected by anterior and posterior arches
   Concave superior articular facets form atlanto-occipital joint with occipital condyle
   Articular facet for the dens (odontoid process) of C2
2. Axis (C2)
   Strongest cervical vertebra
   Dens- projects superiorly from body and provides a pivot for atlas to turn

Question 8

Describe Thoracic Vertebrae (12)-- 
body
foramen
Traverse processes
spinous process

Answer 8

1. Body contain one or two bilateral costal facets for articulation with head of rib
2. Smaller vertebral foramen compared to cervical and lumbar regions
3. Transverse processes are long and strong
   Length diminishes from T1-T12
   T1-T10 contain costal facets for articulation with tubercle of corresponding rib
4. Spinous process slopes significantly postero-inferiorly, overlapping sub adjacent vertebral body

Question 9

Lumbar Vertebrae (5)–
Foraman
Spinous process

Answer 9

Massive body
Vertebral foramen larger than thoracic but smaller than cervical
Short and sturdy hatchet-shaped spinous process

Question 10

Describe the Sacrum and Coccyx

Answer 10

Sacrum:
-Five fused, originally separate, vertebrae
-Sacral cornu
Important landmark for identifying sacral hiatus
-Sacral hiatus
Allows filum terminale of the spinal cord to pass and attach to the coccyx
Results from the absence of laminae and spinous process of the S4-S5 vertebrae
Allows for placement of caudal anesthetic into epidural space
Coccyx
-Four fused vertebrae

Question 11

Describe the Surface anatomy landmarks

Answer 11

C7 spinous process is the vertebra prominens
Scapular spine corresponds to T3
Inferior angle of scapula corresponds with T7 spinous process
Last rib corresponds with T12 spinous process
Iliac crest- Tuffier’s line- corresponds with L4 spinous process
PSIS corresponds to S2 spinous process

Question 12

What are the 6 Ligaments of the vertebral column (6)

Answer 12

Purpose of the ligaments is to stabilize vertebral column
Superficial to deep
Nuchal ligament
Supraspinous ligament
Interspinous ligaments
Ligamentum flava/ flavum
Posterior longitudinal ligament
Anterior longitudinal ligament

Question 13

Nuchal Ligament

Answer 13

Nuchal ligament
Strong, median ligament of the neck
Extends from the occipital protuberance and posterior border of the foramen magnum to the spinous processes of the cervical vertebrae
Acts as a point of muscle attachment from C3-C5

Question 14

Supraspinous Ligament

Answer 14

Supraspinous ligament

Runs along the spinous process from C5 to sacrum after merging superiorly with the nuchal ligament

Question 15

Interspinous Ligaments

Answer 15

Interspinous ligaments
Stabilizes and unites adjacent spinous processes
Weak and membranous, runs entire length of vertebral column.

Question 16

Ligamentum Flava Flavum

Answer 16

Ligamentum flava/ flavum
Broad, tough, pale, yellow, wedge shaped elastic fibrous tissue
Adjoins laminae of adjacent vertebral arches, forming alternating sections of the posterior wall of the vertebral canal. Runs C2 to sacrum. Thickest at the midline at L3

Question 17

Posterior Longitudinal Ligament

Answer 17

Posterior longitudinal ligament
Narrow, weaker band
Runs within vertebral canal along the posterior aspect of vertebral bodies from C2 to the sacrum

Question 18

Anterior Longitudinal Ligament

Answer 18

Anterior longitudinal ligament
Strong broad fibrous band
Covers vertebral bodies and IV discs
Runs from pelvic surface of the sacrum to anterior tubercle of C1 (atlas) and occipital bone anterior to foramen magnum

Question 19

Describe the Spinal Cord–
Begins
Ends
Enlargements

Answer 19

Major reflex center and conduction pathway between the body and the brain
Begins as a continuation of the medulla oblongata (caudal part of the brainstem)
Ends in the conus medullaris, in most adults this corresponds with L1 (T12-L3)

Question 20

Cervical Enlargement

Answer 20

Cervical enlargement extends from C4-T1, anterior rami of these spinal nerves form the brachial plexus that innervate the upper extremity (see upper extremity lecture)

Question 21

Lumboscaral Enlaregment

Answer 21

Lumbosacral (lumbar) enlargement extends from L1-S3 segments of the spinal cord, anterior rami of this region provides the lumbar and sacral plexuses of nerves for the lower extremities (see lower extremity lecture)

Question 22

Describe the the Spinal Cord Dural sac, where does it end

Answer 22

Spinal cord is surrounded by spinal meninges (more on these later), the dura and arachnoid meninges (not pia) continue past the spinal cord to create the dural sac
Dural sac ends at the level of S2, corresponds with PSIS

Question 23

What is the Filum terminale internum

Answer 23

Filum terminale internum is the continuation of the PIA mater

Question 24

How is the filum terminale externum formed

Answer 24

From the inferior end of the conus medullaris, the filum terminale internum descends among the elongated spinal nerve roots of the region and penetrates the end of the dural sac to become the filum terminale externum

Question 25

What is the function of the Filum terminale externum and what is it made up of?

Answer 25

Filum terminale externum passes through the sacral hiatus and attaches to the coccyx posteriorly to anchor the spinal cord and dural sac Filum terminale externum contains dura, arachnoid AND pia mater

Question 26

Describe Spinal Nerves

Answer 26

31 pairs of spinal nerves 8 cervical -C1 emerges between skull and C1 vertebra -C2-C7 emerge superior to corresponding pedicles -C8 and below emerge inferior to corresponding pedicles 12 thoracic 5 lumbar 5 sacral 1 coccygeal

Question 27

Describe the formation of the cauda equina

Answer 27

Results in a bundle of spinal nerve roots in the lumbar cistern of the subarachnoid space caudal to the termination of the spinal cord- referred to as the cauda equina Lower lumbar and sacral nerve roots are the longest since spinal cord ends high in the vertebral column

Question 28

Spinal Nerve Structure | White and gray matter

Answer 28

Spinal cord Gray matter internally, butterfly shaped, unmyelinated interneurons and cell bodies White matter surrounds gray matter, myelinated nerve cells/axons

Question 29

How are the posterior (dorsal) and anterior (Ventral) roots of the spinal nerve formed

Answer 29

Multiple rootlets attach to the anterior and posterior surfaces of the spinal cord and converge to form the posterior and anterior roots of the spinal nerve

Question 30

Describe the posterior (dorsal) and anterior (ventral) root

Answer 30

``` Posterior root (dorsal root) carries afferent sensory information from periphery (skin/deep tissues/viscera) to CNS --Cell bodies of the dorsal root are located outside of the spinal cord at the dorsal root ganglion Anterior root (ventral root) carries efferent motor and autonomic signals from the CNS to periphery --Cell bodies of the ventral root are located inside the anterior horns of the gray matter ```

Question 31

How are spinal nerves formed

Answer 31

The posterior and anterior roots unite to form a spinal nerve, which exits the spinal canal through the intervertebral foramen

Question 32

How are Dorsal and ventral primary ramus

Answer 32

Almost immediately each spinal nerve divides into a dorsal (posterior) primary ramus and a ventral (anterior) primary ramus Dorsal rami supply the deep muscles of the back and skin Ventral rami supply muscles, joints, and skin of the limbs and remainder of the trunk

Question 33

Spinal Meninges- function as?

Answer 33

Surround, support, and protects the spinal cord and spinal nerve roots

Question 34

Dura mater

Answer 34

Dura mater: tough, fibrous outermost covering Separated from the vertebrae by the epidural space Highly vascularized Forms the spinal dural sac, which ends at S2

Question 35

Arachnoid mater

Answer 35

Arachnoid mater: delicate, avascular membrane lines the dural sac, is not attached to dura but is pressed against the dura due to cerebral spinal fluid (CSF) Encloses the subarachnoid space which contains CSF, spinal nerve roots, and spinal ganglia

Question 36

Pia mater

Answer 36

Pia mater innermost covering membrane Directly covers the spinal cord, roots of the spinal nerves and spinal blood vessels Denticulate ligament- extensions that help anchor spinal cord centrally Continues as the filum terminale (internum)

Question 37

Describe the Arterial Supply to the Spinal Cord

Answer 37

From the medulla of the brainstem to the conus medullaris of the spinal cord One anterior spinal artery Two posterior spinal arteries These three arteries run the entire length of the spinal cord but only supply the short superior part Posterior spinal cord has better continuity of blood supply than the anterior spinal cord

Question 38

One anterior spinal artery | Two posterior spinal arteries

Answer 38

Arises from the union of branches of the vertebral arteries Anterior two-thirds of the spinal cord Arise from a branch of either the vertebral arteries or the posterior inferior cerebellar artery Posterior one-third of the spinal cord

Question 39

Describe the Artery of Adamkiewicz (great anterior segmental medullary artery)

Answer 39

Provides circulation to the inferior two thirds of the anterior spinal cord Generally arises from T9-T12 on the left side of the aorta

Question 40

How is the remainder of the Spinal Cord receive Arterial supply

Answer 40

Remainder of spinal cord relies on branches from cervical, deep cervical, vertebral, posterior intercostal and lumbar arteries Enter the vertebral column through the intervertebral foramina

Question 41

Venous drainage of the spinal cord

Answer 41

Venous drainage Veins of corresponding names follow the arteries Epidural space holds the internal vertebral venous plexus (Batson Plexus) Provides alternative venous return to the heart when the inferior vena cava is compressed Empty into the azygos vein or the hemiazygos vein which are located in the abdomen and thorax

Question 42

Superficial respiratory muscles: Serratus posterior superior | Serratus posterior inferior

Answer 42

2nd-5th intercostal nerves (anterior rami) Proprioception for respiration 9th-11th intercostal nerve (anterior rami) Proprioception for respiration

Question 43

Intrinsic Back Muscles | action and innervation

Answer 43

Innervated by the posterior rami of spinal nerves and act to maintain posture and control movements of the vertebral column Superficial, intermediate and deep layers

Question 44

Superficial Intrinsic Back Muscles: Splenius capitis Splenius cervicis Action and innervation

Answer 44

Posterior rami of spinal nerves Laterally flex neck and rotate head to side of active muscles. Extends head and neck together

Question 45

The erector spinae muscles are “sli” Spinalis Longissimus Iliocostalis

Answer 45

Posterior rami of spinal nerves Bilaterally- extends vertebral column Unilaterally- flexes vertebral column

Question 46

Posterior ramus of C1

Answer 46

suboccipital nerve | Motor innervation

Question 47

Posterior ramus of C2

Answer 47

greater occipital nerve (lies slightly lateral) | Sensory innervation

Question 48

Posterior ramus of C3

Answer 48

third occipital nerve (lies medially) | Sensory innervation

Question 49

Anterior ramus of C2-C3

Answer 49

lesser occipital nerve (lies laterally) Sensory innervation Lies outside region of suboccipital triangle but included for completeness

Question 50

Suboccipital Triangle | Region is defined by four postural muscles of

Answer 50

Rectus capitis posterior major Rectus capitis posterior minor Obliquus capitis inferior Obliquus capitis superior

Question 51

Rectus capitis posterior major Attachment Innervation Action

Answer 51

Spinous process C2; occipital bone Suboccipital nerve Head posture

Question 52

Rectus capitis posterior minor Attachment Innervation Action

Answer 52

Posterior tubercle of C1; occipital bone Suboccipital nerve Head posture

Question 53

Obliquus capitis inferior Attachment Innervation Action

Answer 53

Spinous process C2; transverse process of C1 Suboccipital nerve Head posture

Question 54

Obliquus capitis superior Attachment Innervation Action

Answer 54

Transverse process of C1; occipital bone Suboccipital nerve Head posture

Question 55

Posterior ramus of C2 greater occipital nerve (lies slightly lateral) Sensory innervation –

Answer 55

occipital area

Question 56

Posterior ramus of C3 third occipital nerve (lies medially) | Sensory innervation-

Answer 56

occipital area

Question 57

Anterior ramus of C2-C3 lesser occipital nerve (lies laterally) Sensory innervation-

Answer 57

posterior to auricle (ear)

Question 58

How are Dermatomes and Cutaneous Nerves of the back are formed..

Answer 58

Once muscles of the back are innervated the posterior rami of the spinal nerves continue to the surface for cutaneous innervation Dermatomes refer to the typical pattern of innervation of skin by specific spinal nerves Versus a myotome which is the motor innervation of a single spinal nerve