Mark Kozsurek, M.D., Ph.D. mark@kozsurek.hu Composition of the vertebral column Atlanto-occipital and atlanto-axial joints Mark Kozsurek, M.D., Ph.D. mark@kozsurek.hu ED I, 07/12/2016

I. The vertebral column Strong but flexible axis of the human body providing attachment for the shoulder and pelvic girdles and many muscles. Transmits body weight when standing and acts as a shock absorber during walking. Protects spinal cord. It is composed of 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4-6 coccygeal vertebrae.

The vertebral column as a whole primary: thoracic and sacral kyphotic curves lifting the head: cervical lordotic curve siting, standing: lumbar lordotic curve

Composition of the vertebral column How vertebrae are connected together? How these connections provide stiffness and/or flexibility? synostosis synchondrosis syndesmosis synovial joints

synostosis: sacrum, coccygeal bone

synchondrosis: intervertebral disks – shock absorbtion

Intervertebral disks have a gelatinous core (nucleus pulposus) surrounded by a fibrous ring (anulus fibrosus).

syndesmosis: ligaments – balance between stiffness and flexibility

interspinal, supraspinal and intertransverse ligaments

Anterior longitudinal ligament: arrises from the occipital bone as the anterior atlanto-occipital membrane and descends along the vertebrae and is attached bot to the vertebrae and the intervertebral disks. Posterior longitudinal ligament: originates anterior to the foramen magnum as the tectorial membrane and descends behind the vertebral bodies constituting the anterior wall of the vertebral canal. In contrast to the anterior longitudinal ligament it is only attached to the posterior rim of the disks. Ligamentum flavum: fills the gaps among adjacent vertebral arches.

zygapophyseal joints: each vertebrae are connected to their upper and lower neighbours through a pair of superior and inferior articular processes (gliding or plane joints).

Movements of the backbone Cervical part: the most flexible part with flexion-extension, lateral bending and rotation. The neck is much slimmer then the trunk, and the soft tissues do not limit movement. Intervertebral disks are relatively thick compared to the cervical vertebrae. Zygapophyseal articular surfaces are big and capsules are loose.

Thoracic part: very limited movement (that also serves the protection of thoracic organs), mainly lateral bending. Thoracic vertebrae are connected to the sternum via the ribs. Lumbar part: lateral bending and extension mainly, but rotation is impossible.

II. The vertebral column – head junction atlanto-occipital joint atlanto-axial joint

The atlanto-occipital joint Surfaces: superior articular sfacets of atlas and the occipital condyle

Mechanizsm: elipsoid joint (biaxial with two perpendicular axes) transverse axis: flexion - extension („yes-yes”) sagittal axis: lateral bending („well-well”)

The atlanto-axial joint Surfaces: 1. inferior facet of atlas and superior facet of axis 2. tooth process of axis and the atlas with related ligaments

ant. facet of dens – fovea dentis post. facet of dens – transverse ligament of atlas

Mechanism: trochoid joint: vertical axis with rotation („no-no”)

Putting together: Atlanto-occipital joint elipsoid joint Atlanto-axial joint trochoid joint vertical axis Atlanto-occipital joint elipsoid joint sagittal and transverse axes 2+1 axis≈ spheroid joint

lig. apicis dentis: remnant of notochord TUMOR posterior view alar ligament: keeps the occipital bone, the atlas and the axis together and limits their movments. lig. apicis dentis: remnant of notochord

Cruciform ligament of atlas: provides socket for the posterior facet of the tooth process, consists of the transverse ligament and the longitudinal fascicles.

dens axis post. longitudinal lig.

post. longitudinal lig. ant. longitudinal lig. ligg. flava

III. Muscles acting upon the atlanto-occipital, atlanto-axial joints and the vertebral column

nape muscles neck muscles back muscles abdominal mucles cervical vertebral column atlanto-occipital joints, atlanto-axial and neck muscles back muscles abdominal mucles thoracic and lumbar vertebral column

Muscles of the neck (ventrally) → see elsewhere!!! Sternocleidomastoid Rectus capitis lateralis Rectus capitis anterior Longus capitis and colli prevertebral muscles

Prevertebral muscles

Muscles of the neck (ventrally) → see elsewhere!!! Sternocleidomastoid Rectus capitis lateralis Rectus capitis anterior Longus capitis and colli Muscles of the nape (dorsally) Trapezius (found in the nape but a dorsal thoracoappendicular muscle!) Splenius capitis, Longissimus capitis Semispinalis capitis Rectus capitis posterior major and minor, Obliquus capitis superior and inferior prevertebral muscles suboccipital muscles

2. Splenius and longissimus capitis 1. Trapezius 3. Semispinalis capitis 4. Suboccipital muscles

Suboccipital muscles Suboccipital trigone: vertebral artery , suboccipital nerve (from C1)

There is a substantial overlap between muscles acting upon the atlanto-occipital and atlanto-axial joints and the cervical vertebral column!

nape muscles neck muscles back muscles abdominal mucles cervical vertebral column atlanto-occipital joints, atlanto-axial and neck muscles back muscles abdominal mucles thoracic and lumbar vertebral column

ABDOMINAL MUSCLES – see elsewhere! BACK MUSCLES Superficial back muscles (or dorsal thoracoappendicular muscles): are found on the back, but do not act upon the vertebral column, e.g.: Trapesius, Levator scapulae, Rhomboids, Latissimus dorsi. Deep or intrinsic back muscles: Erector spinae Spinalis Longissimus Iliocostalis Transversospinal muscles Semispinalis Multifidus Rotatores ABDOMINAL MUSCLES – see elsewhere!

Depending on their location cervical, thoracis and lumbar parts can be distinguished within the Erector spinae muscles (e.g. Iliocostalis lumborum, thoracis and cervicis, etc.)

Within the transversospinal group the most superficial Semispinalis is almost vertical, the intermediate Multifidus is oblique, while the deepest Rotatores are close to horizontal.

Clinical considerations

Lumbar punction

Spinal disk herniation

Abnormalities of spinal curves

I II X-ray

MRI

Fractures car accident, young victims

Chordoma Rare but malignant tumor arising from the remnant of the notochord typically around the clivus.

Thank you for your attention!