L22 - Anatomy of the Spine Flashcards
General structure of the spine?
5 regions,24 individual vertebrae and 5 fused sacrum and 5 coccyx (33 total)
Increase vertebrae size down the spine
Cervical = 7 Thoracic = 12 Lumbar = 5 Sacral = 5 (fused) Coccygeal = 4 (fused)
3 functions of the spine?
– Provides vertical support forthe bodyand weight of head
– Houses and protects thespinal cord
– Helps maintain an uprightbody position
What are the curvatures of the spine?
Cervical = Lordotic (convex anteriorly) Thoracic = Kyphotic (concave anteriorly) Lumbar = Lordotic Sacral = Kyphotic
No lateral curvature normally
2 functions of spine curvatures?
– Gives column some flexibility
– Biomechanical support of weight of the body is better than a straight spine
What are primary curvatures of the spine?
– Only primary curves present in the newborn
– Concave anteriorly (Lordosis)
Two primary curvatures:
• Thoracic
• Sacral
What are secondary curvatures of the spine?
- Appear after birth
- Concave posteriorly (Kyphotic)
- Help shift trunk weight over legs
2 secondary curvature:
- Cervical curve (3-4 months)
- Lumbar curve (1 year)
Describe Kyphosis?
Abnormally excessive kyphotic curvature
> > hunchback (e.g. localized to thoracic spine)
> > Result from osteoporosis or poor posture
Define Lordosis?
- Exaggerated lumbar curvature
- Result from added abdominal weight (obesity)
Define Scoliosis?
- Abnormal lateral curvature (at thoracic spine)
- Inflation of thoracic cage more affected on the side with more severe scoliosis
Describe the typical vertebra?
2 parts:
- Body (thick anterior weight- wearing structure)
- Vertebral arch (posterior with articular structures for muscle attachment)
- Body and vertebral arch encloses Vertebral foramen and Vertebral canal = contain spinal cord, BV and lymph.
Composition of Vertebral arch?
- Pedicles (2) from posterolateral margins of body
- Laminae (2) extending posteromedially from edge of pedicle
What are the typical spinal processes?
7 processes, one single and 3 paired:
- Spinous process (1): Most posterior and largest, project from laminae junction
- Transverse processes (pair) : Lateral projection on both sides of vertebral arch
- Superior articular processes (pair)
- Inferior articular processes (pair)
Describe the connection between 2 vertebrae?
1) Intervertebral disc link vertebra body to body = cartilaginous joint/ symphysis
2) Zygophyseal joints between vertebral arches: articular processes + synovial joint capsules
Describe the connection between superior and inferior articular processes?
both originate at junction between pedicles and laminae
Each with smooth articular facet
Inferior facet articulate with Superior facet of the next vertebra below > Facet joint, synovial
What forms the intervertebral foramina?
Lateral openngs between adjacent vertebrae between 2 pedicles, bordered by superior and inferior articular processes
Provide passage for spinal nerve and BV
Composition and structure of intervertebral discs?
- Fibrocartilage pads between 2 vertebral bodies
- Mucopolysaccharide, strongly hydrophilic
Peripheral = annulus fibrosis Centre = Nucleus pulposus
Structure of annulus fibrosis of IVD?
Concentric layers of fibers
Longitudinal fibers in superficial layers become more oblique
Fibers in alternate layers slant in opposite direction
How does IVD change in width?
On standing: pressure on nucleus pulposus = water escapes = IVD thinner
On lying down: less pressure on nucleus pulposus = water imbibed = IVD thicker = taller
Structure of nucleus pulposus?
Inner gelatinous region
Acts as a ball in a swivel joint under pressure within annulus fibrosis
ROM and function of IVD?
Flexion, extension (saggital and lateral)
Rotation
Gliding
- Acts as shock absorber between vertebral bodies, allow vertebral column to bend
List the ligaments of the spine?
6 ligaments link vertebrae:
1) Anterior longitudinal ligament
2) Posterior longitudinal ligament
3) Ligamentum flavum
4) Interspinous ligament
5) Supraspinous ligament
6) Intertransverse ligament
Function of ligamentum flavum?
Inside nerual arches
Contains more elastic fibers that spread open neural arches when bending»_space; prevent compression of dural sac containing spinal cord and nerves
List 3 UNIQUE FEATURES OF CERVICAL VERTEBRAE? **
- TRIANGULAR vertebral foramen
- BIFID SPINOUS PROCESS
- TRANSVERSE FORAMEN (located on both sides lateral to the body of vertebrae)
Which vertebrae are specilized for mobility of the head and how?
C1 (Atlas) , C2 (Axis)
Have unique set of articulations:
- C1 has no body and spinous process with 2 articular facet for skull to rest upon + 50% flexion and extension of neck
- Atlantoaxial joint: C1 articulates as a pivot with the dens/ odontoid process of C2 = 50% lateral rotation of head)
Describe the connection between C1 and C2?
- no IVD
- Atlantoaxial joint = C1 receives the dens of C2 at anterior vertebral foramen, stabilized by transverse ligament across the 2 lateral masses
Structure of C1?
- No body and spinous process
* 2 lateral masses connected by anterior and posterior arches
Unique features of C7 vertebra?
Vertebra Prominens(C7)
- Only cervical vertebra to have Non-bifid spinous process
- Longest spinous process of all cervical vertebae (palpable between shoulder blades)
3 unique features of Thoracic vertebrae?
1) HEART SHAPED vertebral body
2) Prescence of articulate facets on sides of each vertebral body and transverse processes to articulate with ribs
3) Spinous processes are LONG and SLANT inferiorly
Define the connection of the ribs to the thoracic vertebrae?
12 ribs:
Each articulate with 2 vertebrae via superior and inferior articular facets between ribs and vertebra
EXCEPT 1st, 11th and 12th ribs that articulate with single vertebra only
- 1-7 ‘True ribs’
- 8-12 ‘False ribs’
- 11,12 are ‘Floating ribs’
5 unique features for lumbar vertebrae?
1) Large and KIDNEY-SHAPED vertebral body
2) TRIANGULAR vertebral foramen
3) Superior and Inferior articular facets are almost vertical (Face up or down)
4) Long and slender transverse processes
5) Short and broad sponous processes
Structure of Sacrum?
S1-S5
5 Fused vertebra with one superior articular process to articulate with L5
Promontory = body of S1
4 sacral foramen, contains sacral canal
Concave anterior surface, Triangular
Forms posterior wall of pelvic cavity, angulated so we sit on coccyx, not sacrum
Where is epidural anesthesia given to block pelvic nerves?
Through sacral hiatus - inferior opening of sacral hiatus bordered laterally by sacral cornua (horn shape projections), closed by fibrous tissue
anaesthetize S2-S5:
Blocks sensation from cervix, perineum, Does not block pain from uterine body
Structure of Coccyx?
Four fused coccygeal vertebrae
Anchors several muscles and ligaments in pelvic region and bears weight when sitting
What determines the movements of vertebral column?
- Facet joints determine range and type of movement
- Control and strength depends on muscle
Range of motion and articulation plane in cervical vertebra?
AP positioned in coronal plane
Allow flexion, rotation and extension
Range of motion and articulation plane in thoracic vertebra?
AP positioned in arc of circle
Allows rotation (limited flexion and extension)
Range of motion and articulation plane in lumbar vertebra?
AP positioned in saggital plane
Allows flexion, extension and lateral bending, No rotation
What provides stability to the sacrum?
Sacroiliac joint stabilized by Anterior, Posterior and Interosseous sacroiliac ligaments
What are the intrinsic/ deep/ true muscles of the back?
Extensors (three layers):
• Superficial (splenius muscles)
• Intermediate (erector spinae muscles)
• Deep (transversospinal muscles, Interspinalis, Intertransversarii)
Flexors (located in the neck, lower back & abdomen)
Function of the extensor muscles of the back?
Function: Bilateral contraction for extension of head or spine; Unilateral contraction for rotation or lateral flexion of head or spine
Structure and function of splenius muscles?
- Splenius capitis = from cervical and thoracic transverse processes to reach the occipital bone = hold head up with bilateral contraction
- Splenius cervicis = Rotates the head toward the side of contraction
Structure and function of erector spinae muscles?
Intermediate group of Deep intrinsic back muscles
3 groups lateral to medial:
Iliocostalis > Logissimus > Spinalis
Function: extend the back, laterally flex the back, and maintain correct posture and curvature of the spinal column
Structure and function of Deep group of Deep intrinsic back muscles?
Run obliquely from lower transverse processes to spinous processes above
Semispinalis = spans 5+ vertebrae Multifidus = spans 2-4 vertebrae Rotatores = spans 1 vertebrae
Function = Rotation, stabilize spine and extensor of back
Location and action of flexor back muscles?
Anterior of spine at cervical and lumbar regions
Action:
Bilateral contraction flex head or spine; Unilateral contraction rotate or laterally flex head or spine
What are the flexors of cervical spine?
- Longuscoli
- Scalenes
- Sternocleidomastoid(SCM)
What are the flexors of the hip?
- Quadratus lumborum
- Psoas major
Compress gap between posterior ribs and iliac crest
What are the flexors of the spine?
Rectus abdominis
Obliques
What is IVD herniation?
Prolapsed IVD (PID) / disc herniation: nucleus pulposus bulges out due to a tear in annulus fibrosis
What structures are affected by IVD herniation?
Lateral: compresses on the spinal nerve leaving at that level
Posterolateral (more common): compresses on the spinal nerve on its way to emerge at the next intervertebral foramen
Cental: Compress on spinal cord or cauda equina
Which spinal regions are more commonly injured by IVD herniation?
Cervical and lumbar discs most commonly injured
How to test for sciatica?
Pain along distribution of sciatic nerve when leg is raised with knee fully extended
What to look for when examining an X-ray of the spine?
- Alignment
- Prevertebral soft tissue thickness
- Width of the vertebral canal
- Irregularities in the anterior and posterior vertebral lines, spinal laminar line and spinous processes
- Size, width and regularity of spinous processes, articular processes and pedicles
- Curvature abnormalities