Anatomy: Back and Spine

From "Back" and "Spinal Cord" lectures

Shape of Spine (Sagittal View)

Primary Curve

T/S

Secondary Curve

C/L

Typical Vertebrae

Typical Vertebra

Typical Vertebra

Typical Vertebra

C7 Spinous Process

Vertebra Prominens

Cervical Body (Distinctive Characteristics)

• Small

• wider from side to side than anteroposteriorly

Cervical Vertebral Foramen (Distinctive Characteristics)

Large and Triangular

Cervical Transverse Process (Distinctive Characteristics)

Foramina transversaria (except C7)

Cervical Articular Processes (Distinctive Characteristics)

Superior: Superoposterior

Inferior: Inferoanterior

Cervical Spinous Processes (Distinctive Characteristics)

C3 - C5 short + bifidil; C6 long, C7 longest

Atlas (Distinctive Characteristics)

• No spinous process or body; consists of two lateral masses connected by anterior and posterior arches

• Concave superior articular facets; flat inferior facets

Axis (Distinctive Characteristics)

• Strongest Cervical Vertebra

• Distinguishing feature is the Dens, which the atlas pivots around. 50% of all C-spine rotation.

T1, T11, and T12 are considered _____ vertebrae

transition

The thoracic spine has (more/less) lateral flexion than expected due to _____

less; ribs

Thoracic Body (Distinctive Characteristics)

Heart-shaped

Thoracic Vertebral Foramen (Distinctive Characteristics)

Circular and smaller than cervical/thoracic

Thoracic Transverse Process (Distinctive Characteristics)

• long and strong

• length diminishes from T1 - T12

Thoracic Articular Facets (Distinctive Characteristics)

Superior: posterolaterally

Inferior: anteromedially

Thoracic Spinous Process (Distinctive Characteristics)

• Long

• Slopes posteroinferiorly

• Overlaps subadjacent vertebral body (sometimes completely)

Lumbar Body (Distinctive Characteristics)

Massive

Lumbar Vertebral Foramen (Distinctive Characteristics)

• Triangular

• Larger than thoracic, smaller than cervical

Lumbar Transverse Processes (Distinctive Characteristics)

• Long and slender

• Accessory process on posterior surface of base of each process

Lumbar Spinous Process (Distinctive Characteristics)

• Short and sturdy

• Hatchet shape

Lumbar Articular Processes (Distinctive Characteristics)

Superior: Posteromedially

Inferior: Anterolaterally

Mamillary process on posterior surface of each superior articular process.

Pars Interarticularis

Oblique “neck” between Spinous process and superior articular facet

Spondylolisthesis

Fx of Pars Interarticularis

Joints of the Spine (6)

In Utah, Zebras Chase Crazy Snakes

• Intervertebral

• Uncovertebral

• Zygapophyseal

• Craniovertebral

• Costovertebral

• Sacroiliac

Intervertebral discs degenerate due to _____ which eventually leads to _____

Loss of ability to hold water and therefore resist compressive force; degenerative joint disorder (of the zygapophyseal joint)

Ligamentum flavum

• Connects laminae of adjacent vertebrae

• Resists flexion

Anterior longitudinal ligament

• On the anterior surface of each vertebra

• From occiput/C1 to sacrum

• Resists extension

Posterior longitudinal ligament

• On the posterior body of each vertebra

• From C2/occiput (as tectorial membrane) to sacrum

• Resists flexion

• Gets progressively weaker inferiorly

Interspinous ligament

• Between spinous processes

• Resists flexion

Supraspinous ligament

• Between tips of spinous processes

• C7 - S1

• Resists flexion

• Much tougher than interspinous ligament

The superior articular facet of the atlas articulates with _____

occipital condyles

The atlantooccipital joint primarily moves in _____ and _____.

Flexion; extension

The atlantoaxial joint primarily moves in _____.

rotation

The anterior atlantooccipital membrane limits _____, while the posterior atlantooccipital membrane limits _____.

Extension; flexion

The tectorial membrane is an extension of the _____ and goes into the _____ at the base of the skull.

posterior longitudinal ligament; foramen magnum

The _____ ligament in the atlantoaxial complex limits rotation

cruciate

Extrinsic back muscles primarily move the _____, while intrinsic back muscles move the _____.

upper extremities; back

Extrinsic back muscles are innervated by ____ rami, while intrinsic back muscles are innervated by _____ rami.

anterior; posterior

Intrinsic Superficial Back Muscles

• Splenius

  • Splenius Cervicis

  • Splenius Capitis

Intrinsic Intermediate Back Muscles

• Spinalis

• Longissimus

• Iliocostalis

Splenius fiber length:

4 - 6 segments

Semispinalis fiber length:

4 - 6 segments

Multifidus fiber length:

2 - 4 segments

Rotatores fiber length:

1 - 2 segments

Intrinsic Deep Back Muscles

• Semispinalis

• Multifidus

• Rotatores

Muscles of the Suboccipital triangle

• Obliquus Capitis Superior

• Obliquus Capitis Inferior

• Rectus Capitis Posterior Major

Suboccipital Region is composed of which 3 bones

• Axis

• Atlas

• Occiput

Number of C, T, L, S, C vertebrae

7, 12, 5, 5, 4

Number of C, T, L, S, C nerve pairs

8, 12, 5, 5, 1

While most spinal nerves come out under their respective vertebrae, ____ nerves come out on top of their respective vertebrae.

Cervical

Put these in order (Medial to Lateral)

• Posterior root

• Spinal nerve

• Spinal ganglion

• Posterior rootlets

• Posterior ramus of spinal nerve

1. Posterior rootlets

2. Posterior root

3. Spinal ganglion

4. Spinal nerve

5. Posterior ramus of spinal nerve

The spinal ganglion is composed mostly of _____

cell bodies for afferent fibers coming back to spinal cord

Posterior/Anterior ROOTS have (one/two) nerve(s) in each of them

One

Posterior/Anterior roots have only Afferent/Efferent neurons, respectively.

Posterior/Anterior RAMI have (one/two) nerve(s) in each of them

Two

Because the rami exist past the spinal nerve, they have both kinds of neurons (afferent and efferent). However, the posterior rami is mostly afferent neurons; anterior rami is split 50/50.

The denticulate ligament is made of _____

pia mater

The function of the denticulate ligament is to _____

stabilize the spinal cord

The location of the denticulate ligament is _____

Between the arachnoid and pia mater

You can find cerebrospinal fluid in the _____

subarachnoid space

You can find a fatty matrix in the _____

epidural space