FACTS & HINTS

High-Yield Facts

Clinical Points

Lumbar Puncture:Performed for retrieval of cerebrospinal fluid (CSF) from the lumbar spinal cistern. The patient is placed in the left decubitus position, flexed in the fetal posture with the supracristal line vertical. Puncture should be made at the L3/4 (immediatelysuperior) or L4/5 (immediatelyinferior) interspace in the midline of the back, to avoid the spinal cord.

Mnemonics

Memory Aids

Lumbar puncture: To keep the cord alive, keep the needle between L3 and L5!

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15 Bones and Ligaments

STUDYAIMS

At the end of your study, you should be able to:

Identifythe significant parts of a typical vertebra and understand regional variations

Identifythe specialized vertebrae

Know the attachments and function of the vertebral ligaments

Describe the spine, its curvatures, and gross vertebral column movements

Describe the type, location, and movements of the joints of the vertebral column

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GUIDE

Back and Spinal Cord: Bones and Ligaments

Vertebral Column

[Plate 150, Vertebral Column]

approximately72 to 75 cm long (25% of length because of intervertebral discs) 33 vertebrae (can vary 32-34)

7 cervical, 12 thoracic, 5 lumbar, 5 sacral, 4 (3-5) coccygeal

Typicallyhave: body; vertebral arch (2 laminae, 2 pedicles) and foramen; spinous (1) and transverse (2) processes; articular processes (4)

Fibrocartilaginous intervertebral discs

Allow movement between vertebral bodies (in cervical, thoracic, and lumbar regions) Curvature (may be primary or secondary-see below)

Cervical anterior convexity(2°)

Thoracic anterior concavity(1°)

Lumbar anterior convexity(2°) Sacral anterior concavity(1°)

Vertebrae

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[Plate 152, Lumbar Vertebrae]

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Cervical vertebrae

Permit forward/lateral flexion, extension, rotation

C1 (Atlas): No bodyor spinous process; articulates with occipital condyles via paired lateral masses and with the axis via the superior articular facets and dens of the axis; groove on superior aspect of the posterior arch for vertebral arteries and dorsal ramus of C1

C2 (Axis): Dens (odontoid process), large superior articular facets for C1

C3-C5: Short bifid spinous processes (anterior tubercle of C6 is the carotid tubercle, which the carotid artery can be compressed against to control bleeding)

C6-7: long, nonbifid spinous processes

C7 (Vertebra prominens): long (nonbifid) spinous process; small transverse foramina that transmit accessoryvertebral veins NOT vertebral artery

Have transverse processes with anterior and posterior tubercles and foramina (foramina transversaria), which transmit vertebral arteries and veins and sympathetic nerves plexuses

Thoracic vertebrae

Are relativelyrigid, mainlyallow rotation of the trunk

T1-T4:Atypical-have some features of cervical vertebrae

T5-T8: Typical

T9-T12:Atypical-have tubercles similar to mamillaryand accessoryprocesses of lumbar vertebrae

Have long transverse processes that extend posterolaterally Lumbar vertebrae

Are relativelymobile, permit forward/lateral flexion and extension but little rotation

Have accessoryprocess found on posterior surface of the base of each transverse process for attachment of medial intertransverse lumborum muscle

Have mamillaryprocess for attachment of multifidus and medial intertransverse muscles

L5: massive bodyand transverse processes and is thicker anteriorly-contributes to the lumbosacral angle (usually130°-160°) and carries the weight of the upper body

Sacrum (sacral vertebrae)

Composed of five vertebrae that fuse at about 20 years of age, inferior portion is nonweightbearing

Articulates with "hip" bones at sacroiliac joints Has concave pelvic surface

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Is wider in females than males

Has a sacral canal (continuation of vertebral canal) that contains cauda equine

Has the following features:

Sacral hiatus (termination of sacral canal) that contains filum terminale

Median crest: fused spinous processes

Paired medial crests: fused articular processes

Paired lateral crests: fused tips of the transverse processes

Sacral corneae that project inferiorlyon either side of sacral hiatus

Coccyx(coccygeal vertebrae)

Consist of three to five coccygeal vertebrae, inferior three fuse as coccyxin midlife

Has coccygeal corneae that articulate with sacral corneae

Provides site of attachment for gluteus maximus, coccygeus muscles, and anococcygeal ligament

Is joined to the sacrum bythe sacrococcygeal symphysis

Summary of vertebral characteristics

Vertebrae Distinctive Features

Joints

[Plate 21, Cervical Vertebrae: Uncovertebral Joints]

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Intervertebral (IV) discs

Connect articulating surfaces of adjacent vertebral bodies

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Are integral part of secondarycartilaginous joints between vertebral bodies (except C1/2)

Are composed of a tough annulus fibrosus surrounding an avascular, gelatinous nucleus pulposus

Act as "shock absorbers" and semifluid ball bearings to provide small movements between individual vertebrae Zygapophysial (or facet) joints

Are synovial joints between the superior and inferior articular processes

Are surrounded bythin, loose articular capsule

Permit gliding movements between vertebrae Atlanto-occipital joints

Are synovial joints between the lateral masses of atlas and occipital condyles

Permit flexion/extension and some lateral bending and rotation Atlantoaxial joints

Are three synovial joints between the inferior lateral masses of C1 and the superior facets of C2 and between the anterior arch of C1 and the dens of C2

Permit rotation of C1 (and the head), which is limited bythe alar ligaments Costovertebral joints Synovial, between the vertebrae and ribs (see: Thorax) Sacroiliac (SI) joints. Synovial joints (see: Pelvis and Perineum)

[Plate 22, External Craniocervical Ligaments]

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[Plate 23, Internal Craniocervical Ligaments]

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[Plate 153, Lumbar Vertebrae: Radiographs]

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[Plate 156, Vertebral Ligaments: Lumbar Region]

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