THE BACK AND VERTEBRAL COLUMN

Dr. Robert J. Cowie

OBJECTIVES:

The student should observe on the cadaver, and be able to:

• 1. Identify and demonstrate surface landmarks and osteological features of the back and suboccipital regions on a living subject and the cadaver.

  2. Identify the course and attachments of the muscles of the back and suboccipital triangle giving their actions, innervations and blood supply.

  3. Define the intrinsic and extrinsic muscles of the back.

  4. Identify and give the boundaries of the triangle of auscultation, lumbar triangle and suboccipital triangle. What is the clinical significance of these triangles?

  5. Compare and contrast the different regions of the vertebral column, giving numbers and distinguishing characters of vertebrate in each region.

  6. Name and describe the normal and abnormal curvatures of the adult vertebral column, and know their developmental history from the fetal condition.

  7. Discuss the anatomical basis of a herniated disc and its symptoms.

  8. Describe the various conditions that may result from trauma to, and abnormal development of, a vertebra.

  9. Explain anatomically why a spinal tap is performed between L3-L4? What structures are traversed by the needle? What is caudal anesthesia and where is it administered? Why?

  10. Discuss the possible outcomes from a dislocation and/or fracture of the spine at different locations.

  • Required Reading: M & A, pgs. 190-209.

    OUTLINE:

I. Introduction: View the lecture topics in light of the following-

A. Functions the back and the vertebral column

1. movement and locomotion

2. upright posture

3. protection

B. Acute and chronic back problems result from "trade-offs"

1. "Form (and pathology) follows function"

I. Anatomy of the Back

A. Surface Anatomy: Landmarks and levels

1. External occipital protuberance

2. Spinous process of C7: vertebra prominens

3. Thoracic spines

4. Median sacral crest

5. Coccyx

6. Superior and inferior angle (T7) and spine of the scapula:

7. Iliac crest: L4 vertebra

8. Dimple for posterior superior iliac spine: S2

9. Posterior median furrow

10. Natal cleft: begins at S4

• B. First and second anatomical layers: muscles that act on the upper

  extremity: extrinsic muscles of the back (and UE).

1. Trapezius

• • a. Blood supply: superficial branch of transverse cervical artery

b. Innervation: CN IX & C3-C4

c. Actions

2. Latissimus dorsi

a. Blood supply: thoracodorsal artery

b. Innervation: thoracodorsal nerve

c. Actions

3. Levator scapulae

a. Innervation: dorsal scapular nerve

b. Actions

4. Rhomboid major

a. Blood supply: dorsal scapular artery

b. Innervation: dorsal scapular nerve

c. Actions

5. Rhomboid minor (see above)

C. Third anatomical layer: These respiratory muscles are extrinsic, too.

1. Serratus posterior superior

2. Serratus posterior inferior

• D. Fourth Layer: True, or intrinsic, back muscles - develop segmentally; all have multiple origins and insertions; they are all innervated by the dorsal primary rami (d 1^o rami) of segmental (spinal) nerves; they may be divided into four major groups; passing from superficial to deep:

1. Splenius capitis and splenius cervicis

2. Erector spinae: from lateral to medial

a. Iliocostalis: hip to ribs

b. Longissimus: longest of the back, transverse proc. and ribs

c. Spinalis: skip several (4-6) spines

•  
  • 3. Transversospinalis: from superficial to deep

a. Semispinalis: from spine to transverse proc.

b. Multifidus: multiple slips

c. Rotatores: deepest rotators

4. Segmental muscles: reach between adjacent segments

A. Interspinalis: from spine to spine

B. Intertransversarii: from trans. proc. to trans. proc.

E. Suboccipital Triangle

1. Muscles

a. Obliquus capitis inferior

b. Obliquus capitis superior

c. Rectus capitis posterior major

2. Contents: C-l (D1^o ramus), vertebral artery, and deep cervical venous complex

3. Actions: rotate occipital condyles and atlas on axis

F. Muscular Spaces

1. Triangle of auscultation: trapezius, latissimus dorsi, & border of scapula

a. listen here for lung sounds

2. Lumbar triangle: external abd. oblique, latissimus dorsi, & iliac crest

III. Vertebral column

A. Types and morphology of the vertebrae

1. Cervical - 7

2. Thoracic - 12

3. Lumbar - 5

4. Sacral - 5, usually fused

5. Coccyx - 3, normally always fused

B. Anatomy of the vertebral column

1. Development and function of vertebral curvatures

a. Primary curvatures- embryonic and "C" shaped

b. Secondary curvatures- functional and opposite in direction

c. Abnormal curvatures- excessive in degree; typical at certain levels

i. kyphosis- K-shaped; thoracic

ii. lordosis- "sway-backed"; lumbar

iii. scoliosis- lateral;

d. Dislocations and fractures

i. paraplegia; fx. or (disartic.) at vertebral level T1 (or below)

ii. quadriplegia; fx. at C4

iii. asphyxiation; fx. at C3

e. Spinal tap; to remove cerebrospinal fluid (CSF) for analysis

i. choice of location and cautions

f. Caudal anesthesia; sacral hiatus; epidural

2. Articulations of the Vertebral Column

a. Cranium: function and movement

b. Scapula: less support and "extreme" movement; one joint

c. Pelvis: more support and less movement; fused joints

3. Intervertebral Articulations

a. Synovial: zygapophyseal

i. superior and inferior articulating facets

ii. clinical considerations:

a) arthritis & rheumatism

b. Symphysis: intervertebral disc; non-synovial

i. annulus fibrosus

ii. nucleus pulposus

iii. clinical considerations:

a) herniated disc

b) lumbago

c) sciatica

4. Ligaments

a. Anterior longitudinal ligament

b. Posterior longitudinal ligament

c. Supraspinous ligament

d. Interspinous ligament

e. Ligamentum flavum

f. Ligamentum nuchae