ANAT 1005: Unit 2, Module 1 - Vertebral Column & Deep Back

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28 to 30 inches in length
33 vertebrae
- 24 true vertebrae
(7 cervical, 12 thoracic, 5 lumbar)
- 5 sacral (sacrum)
- 4 coccygeal (coccyx)
Vertebral Column Bones
protects spinal cord and provides a supporting structure
Vertebral Column Function
Presents on anterior aspect:
- 2 concavities: thoracic and sacral regions, are primary curvatures (present at birth)
- 2 convexities: cervical and lumbar regions, are secondary curvatures (absent at birth)
Vertebral Column Concavities
- anterior body
- vertebral foramen
- posterior vertebral arch: composed of 2 pedicles and 2 laminae
- has 7 processes: 1 spinous, 2 transverse, 4 articular (2 superior and 2 inferior)
Typical Vertebra Anatomy
Concavities/Convexities
Vertebrae Types
Lumbar Vertebrae
Thoracic Vertebrae
Cervical Vertebrae
- shock absorber
- allow movements
- nucleus pulposus
- annulus fibrosus
Intervertebral Disc Anatomy
a center of water and gelatinous substance
Nucleus Pulposus
a peripheral more fibrous layer of fibrocartilage
* thicker anteriorly than posteriorly - b/c most of movements are flexion of vertebral column, not extension (limited extension b/c of posterior bone processes)
Annulus Fibrosus
intervertebral disc undergoes changes - decreased water content and increased stiffness
Intervertebral Disc & Aging
- several articular surfaces covered with hyaline cartilage
- superior and inferior aspects of the vertebral body for articulation with the intervertebral disc
- facets also at the tip of the 4 articular processes
- superior articular processes will articulate with the inferior articular processes of vertebra above
- opposite being true for the inferior articular processes
Articular Surfaces Characteristics
- presence of a foramen in the transverse process, the foramen transversarium, allowing the passage of vertebral veins through all 7 cervical vertebrae with the artery passing usually though the upper 6 cervical vertebrae
- groove for spinal nerve (in the transverse process)
- uncinate process
- except for C1 and C7, the spinous processes are bifid
- vertebral foramen is large and somewhat triangular
Cervical Vertebrae Characteristics
- does not have a vertebral body nor a spinous process
- an anterior and posterior arch
- articular surfaces on upper aspect for the occipital condyles (upward and downward movement of skull over C1, like when saying "Yes)
C1 : Atlas Characteristics
the odontoid process or dens, projecting superiorly from the superior aspect of its body
C2: Axis Characteristics
- note that as a consequence, there is no intervertebral disc between C1/C2
- note how the dens of the axis articulates with the articular facet found on the posterior aspect of the anterior arch of the atlas (movement of rotation of C1 over C2, like saying "No")
- note the cruciate ligaments made of 3 separate parts: the transverse ligament of the atlas and the superior and inferior longitudinal bands
C1-C2 Characteristics
- body is a medium size with a heart shape
- vertebral foramen is small and circular
- spinous process is long and inclined downward
- costal articular surfaces (facets) on the side of the vertebral body for articulation with the head of the matching rib
- costal facets on the transverse processes for articulation with the tubercle of the matching rib
- note that T11 and T12 do not have facets for the tubercle of the ribs on their transverse processes
Thoracic Vertebrae Characteristics
- vertebral body: large and kidney shaped
- vertebral foramen is triangular
- laminae: thick with strong pedicles but with long and slender transverse processes, L3 transverse processes being the widest
- mammillary and accessory processes
Lumbar Vertebrae Characteristics
- fusion of the 5 sacral vertebrae
- wedge-shaped bone with an anterior concavity
- superiorly: intervertebral disc L5-S1
- inferiorly: coccyx
- laterally: articulates with the iliac portion of the pelvic bone
- sacral promontory
- vertebral foramina: sacral canal
- anterior and posterior sacral foramina for ventral and dorsal primary ramie of sacral nerves
Sacrum Characteristics
superior articular processes face upward and backward, with inferior being downward and forward
Orientation of Articular Surfaces (Cervical)
superior articular processes face backward and laterally, with the inferior being forward and medially
Orientation of Articular Surfaces (Thoracic)
superior articular processes face medially, with the inferior facing laterally
Orientation of Articular Surfaces (Lumbar)
- intervertebral joints are different due to the presence of the uncinate process
- spinal nerve rests in its groove upon exit through its intervertebral foramen
Cervical Region, Uncinate Processes
- intervertebral foramina are created by the juxtaposition of the pedicles of the lumbar vertebra above and below
- spinal nerves exit in a downward manner through these openings
Lumbar Column, Intervertebral Foramina
Atlas
Axis
- anterior longitudinal ligament
- posterior longitudinal ligament
- ligamentum flavum - two separate (right and left)
- interspinous ligament (between spinous processes of vertebra)
- supraspinous ligament (ligamentum nuchae in the cervical region) - tip to tip of spinous processes
Spinal Cord Ligaments
two separate (right and left)
Ligamentum Flavum Ligament
between spinous processes of vertebrae
Interspinous Ligament
ligamentum nuchae in cervical region - tip to tip of spinous processes
Supraspinous Ligament
18-20 inches in length (shorter than vertebral column, column grows at faster rate than cord)
Spinal Cord Length
cervical (C5-T1) and lumbosacral (L2-S3)
Spinal Cord Enlargements
31 pairs
- 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
Spinal Nerve Pairs
- C1 to C7 leave the vertebral column above the matching vertebra with C8 spinal nerve exiting below the C7 vertebra
- From T1 downward, the spinal nerves exit below their same numbered vertebrae (T1-L5)
Spinal Nerve - Exiting in Cervical/Thoracic
- S1-S4 pass through the sacral foramina (1-4)
- S5-Coc1 pass through the sacral hiatus
Spinal Nerve - Exiting in Sacrum/Coccyx
spinal cord stops at the tip of the spin of L1 or the upper border of L2
Spinal Cord Ending Position
tapered end of the spinal cord
Conus Medullaris
spinal cord dorsal and ventral roots below the L1 level collectively
Cauda Equina
- each spinal nerve is attached to the spinal cord by anterior root (motor) and a posterior root (sensory)
- each root is formed by a series of rootlets
- the length of the root increases progressively from the cervical region to the lumbar region
- recall the conus medullaric and cauda equina
Spinal Nerves Characteristics
a tough, protective, impermeable outer layer that encloses the spinal cord and the cauda equina; in ends at the level of the 2nd sacral vertebra
Spinal Cord Meninges:
Dura Mater
delicate impermeable membrane, found deep to the dura mater, separated from the most internal layer (pia mater) by a subarachnoid space - filled with cerebrospinal fluid
Spinal Cord Meninges:
Arachnoid Mater
vascular membrane covering the spinal cord itself, ending at L1 with the filum terminale - note also the denticulate ligaments
Spinal Cord Meninges:
Pia Mater
blood supply to the spinal cord is from 3 main longitudinal arteries - 2 posterior spinal arteries and 1 anterior spinal artery
Spinal Cord Blood Supply -
Main Arteries
branching from the segmental spinal artery, enter through the intervertebral foramina to anastamose with the network created by the 3 main arteries
Spinal Cord Blood Supply -
Radicular Arteries
- valveless system of veins: composed of the internal vertebral venous plexus and the external vertebral venous plexus
- note the internal vertebral venous plexus is outside the dura mater
Spinal Cord Venous Network
- spinalis (medially)
- longissimus
- iliocostalis (laterally)
Deep Back Muscles -
Erector Spinae Muscles (1st Group)
- semispinalis
- multifudus
- rotators
Deep Back Muscles -
Transversospinalis Muscles (2nd Group)
- intertransversarius muscles
- interspinales muscles
Deep Back Muscles -
3rd Group
posterior longitudinal ligament: inferior and posterior aspect of each intervertebral disc, is fairly narrow and weak band - clinical implications?

disc can rupture with certain types of movements - stress with flexion

herniated discs - always injures spinal cord associated with second disc (between L4-L5 = L5)
*only exception to rule: C7-T1 - nerve pressed on is C8
Herniated Discs and Spinal Nerves
d. 7
How many processes in a typical vertebra?
a. 1
b. 2
c. 4
d. 7
e. 9
d. C7 vertebra
The vertebral artery passes through the foramen transversarium of all cervical vertebrae, except?
a. C1
b. C2
c. C6
d. C7
e. C8
c. 3rd group
The interspinales are muscles that belong to which group of true back muscles?
a. 1st group
b. 2nd group
c. 3rd group
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