HUMB1004 Week 5: Cervical spine and sacrum

Relative to the average vertebra, is the cervical vertebral body smaller or larger?

Small

What feature do cervical vertebra have that allow for muscle attachment in addition to transverse processes?

Uncinate processes

Where are the uncinate processes located?

Superolaterally

True or false: cervical spinous processes are bifid (forked)

True

What feature is unique to cervical vertebra transverse processes?

They have a transverse foramen

What is the purpose of the transverse foramen of cervical vertebra?

Allows passage of vertebral artery, vertebral veins, and some sympathetic nerves

What feature is found on the lateral end of the transverse processes of cervical vertebra?

Tubercles (anterior and posterior)

What is the articular pillar?

Fused superior and inferior articular processes of cervical vertebra only

Describe the vertebral foramen of a cervical vertebra

Large and triangular

How are the facets of cervical vertebra oriented?

At 45 degrees to the transverse plane

True or false: the facets of cervical vertebra lie much closer to the transverse plane than any other vertebra

True

True or false: intervertebral joints in cervical region are true synovial

True

What are uncovertebral joints?

Joints between the uncinate processes and vertebral bodies of the cervical vertebrae

What structure do the intervertebral foramina passage?

Spinal nerves

In cervical vertebrae, what structures form the intervertebral foramen?

The uncovertebral joint and the articular pillar

Where does the vertebral artery V1 arise?

From the subclavian artery

Why is V1 named pre-foraminal?

Because it arises at the lateral aspect of cervical vertebra then usually enters the transverse foramen at C6. Prior to this, does not course through vertebral foramen

How often do V1/pre-foraminal arteries to enter the spinal column at C6?

70-80% of the time

True or false: V1 most commonly enters the vertebral column at C7

False, 70-80% enter at C6

Where is V2 located?

When V1 enters transverse foramen up to C2, through the transverse foramen

What is the other name for V2?

Foraminal segment of vertebral artery

Where does V3 begin?

At C2

Describe the course of V3 until it becomes V4

Torturous (lots of bends and twists) until the transverse foramen of C1, then course posteriorly to form a groove at C1, then pierces a membrane and dura

What does V3 become once it pierces the dura?

V4

Another name for V4

Intra-dural segment

What is the vertebral artery termed superior to the intra-dural segment?

The Basilar artery

Why are vertebral and basilar arteries important?

They supply the brain stem and spinal cords (commonly imaged)

True or false: Basilar arteries supply the brain

False, internal carotid arteries supply brain, basilar and vertebral arteries supply the brain stem and spinal cords

What is the relation between the common carotid artery and C6?

The CCA lies just anterior to the anterior tubercle of C6

What is the anterior tubercle of C6 also called?

The carotid tubercle

What is the importance of the carotid tubercle?

In the case of a haemorrhage, the CCA can be compressed against the carotid tubercle to stem the flow of blood

What are the arrows pointing to and what might have caused it?

Carotid artery tear. Blunt trauma i.e. CCA pushed against the tubercle which has caused a tear

CCA and IJV travel in their own connective tissue sheath, called the _______

Carotid sheath

Other name for C1

Atlas

Why is C1 atypical?

It has no vertebral body, instead it has an anterior arch with an anterior tubercle for muscle attachment, and a posterior arch (modified laminae) with a posterior tubercle

Instead of transverse processes, what does C1 have?

Lateral masses

Where are the superior and inferior articulating processes located on C1?

On the superior and inferior surfaces of the lateral masses

How to distinguish inferior and superior surfaces of C1

Superior aspect has elongated anterior to posterior processes as it must articulate with occipital condyles, inferior only must articulate with axis, hence has a rounded projection. Additionally, there is a groove for V3 section of artery on the anterior surface of the posterior arch superiorly

Where is the Atlanto-occipital joint located?

Between superior articulating processes of Atlas and occipital condyles

What movements are available at the Atlanto-occipital joint?

Flexion and extension. No rotation or lateral flexion are available

What features of C2/axis make it atypical?

It has a dens/odontoid process, and a similar body to C1

What special articular joint does C1/C2 have? (between the dens and anterior arch of C1)

The median atlantoaxial joint

What is the name of the joints found between articulating facets of C1/2?

Latero-atlantoaxial joints

What movement are the median and lateral atlantoaxial joints responsible for? (in combination)

50% of total craniocervical rotation

True or false: the craniocervical rotation between atlas and axis are reliant on the close articulation of the dens of axis and the anterior arch of the atlas

True

What occurs when there is a loss of articulation at the median atlantoaxial joint?

Loss of stability at joint

What are the 3 ways to lose stability at the medial atlantoaxial joint?

Fracture of the odontoid process, Os odontoideum, and Os terminale

True or false: the odontoideum ossifies as a part the axis

False, it starts at its own centre of ossification and later fuses with the VB of axis

What is Os Odontoideum and what are its implications?

The failure of the odontoid process to fuse with axis, causes instability

What is the fovea Dentis?

The notch in the atlas for the dens to reside in

A

Internal jugular vein

What is B?

Common carotid artery

What is C?

Transverse foramen

What is D?

Spinal cord in vertebral foramen

What is the carotid sheath?

The connective tissue in which the CCA and IJV travel in

What is shown here?

Os odontoideum

What is shown here

Os odontoideum

Is Os terminale a cause for concern?

No, just notable. Still stable

A typical cervical vertebra consists of body, foramen, spinous process, transverse process (describe)

Small VB, triangular vertebral foramen, bifid spinous process and modified transverse foraminae

The transverse foramen of cervical vertebrae contain:

Vertebral arteries

Bifid spinous processes are found on vertebrae _____

C2-6

C1 does not have a vertebral body. Instead, it has…

Anterior tubercle of anterior arch

C2 is not a typical vertebra as it:

Has an odontoid process on the anterior superior surface

Superior articulating process

Sacral body

Sacral canal

Ala

Median sacral crest

Dorsal sacral foramina

Coccyx (2-4 bones fused)

Sacral hiatus

Lateral sacral crest

Base

Ala

Sacral promontory

Ventral sacral foramina

Apex and coccyx

Transverse lines (site of vertebral fusion)

Body of first sacral body

Which direction is the base of the sacrum tilted towards?

Anteriorly

Which direction is the apex of the sacrum tilted towards?

Posteriorly

What joint is formed at the apex of the sacrum and the coccyx?

The sacrococcygeal joint

Sacroiliac joint

True or false: the sacroiliac joint has a great degree of movement

False, it is moveable but to a very limited degree

What part of the sacroiliac joint is synovial?

The first 1/3^rd

What part of the sacroiliac joint is fibrous (syndesmoses)

The last 2/3rds

What type of cartilage is found on the sacral part of the sacroiliac joint?

Hyaline

What type of cartilage is found on the iliac part of the sacroiliac joint?

Fibrocartilage

Orange:

Sacrum/sacral ala

Red:

Sacroiliac joint

Yellow:

Ilium

True or false: All sacroiliac joints are the same shape

False, some are deeper, some are shallower

Describe the dorsal surface of the sacrum

Roughened

Describe the ventral surface of the sacrum

Smoothened

Articular processes of sacrum are articulated in what plane?

Coronal

What is the sacral hiatus?

Lack of 5^th tubercle

What is the importance of the sacral hiatus?

Can be used to introduce epidural anesthesia

Where does the dura end? Why is this important?

At S2, hence anaesthesia can be introduced as high as S3 and the dura will not be perforated

How are the sacral horns and coccygeal cornu related?

The coccygeal cornu opposes the sacral horns

What is the type of joint at the sacrococcygeal joint?

Symphysis (fibrocartilaginous)