M: Vertebral column and spinal cord Flashcards
What are the 7 components of the back (the posterior part of the trunk)?
1) Skin
2) Subcutaneous tissue
3) Vertebral column
4) Spinal cord and meninges
5) Ribs
6) Nerves and vessels
7) Muscles
What are the 2 main parts of a typical vertebra?
1) Body which supports the vertebral column and is connected to the intervertebral discs
2) A vertebral/neural arch posteriorly
What are the 4 subdivision of the vertebral arch?
1) Pedicle
2) lamina
3) Superior and inferior articular processes
4) Spinous and transverse processes
What is meant by the vertebra prominens and what is it used for?
Spinous process of C7, used as a bony landmark to count vertebra
Which 3 structures hold vertebra together?
1) Facet joints
2) Intervertebral discs
3) Ligaments
What do zygapophyseal joints connect?
The superior and inferior articular processes of adjacent vertebra
What structure provides flexability to the spine aswell as acting as shock absorbers?
Intervertebral discs
What are the attachments and function of the anterior longitudinal ligament?
Superiorly - base of skull
Inferiorly - anterior surface of the sacrum
Along its length it is attached to the vertebral bodies and intervertebral discs
Function - Resists hyperextension (only ligament to do so)
What are the attachments and function of the posterior longitudinal ligament?
Superiorly - Intracranial aspect of base of skull
Inferiorly - posterior surface of sacrum
Along its length it is attached to the vertebral bodies and intervertebral discs
Function - prevents posterior herniation of intervertebral discs and resists hyperflexion
What is the name of the upper part of the posterior longitudinal ligament from the base of the skull to CII?
Tectorial membrane
What are the attachments of the ligamentum flavum and its function?
Anterior surface of the lamina of the vertebra above
Posterior surface of the lamina of the vertebra below
Function - Forms part of the posterior surface of the vertebral canal, resists separation of the lamina in flexion and assists in extension back to the anatomical position
Describe the ligamentum nuchae?
Triangular, sheet like structure in the median sagittal plane
What are the attachments of the ligamentum nuchae?
Base - attached to skull from external occipital protuberance to foramen magnum
Apex - spinous process of C7
Length - posterior tubercle C1 and spinous processes C2-6
What is the function of the ligamentum nuchae?
Supports the head, resists flexion, facilitates turning the head back to anatomical position and provides a sight for muscle attachment
What are the attachments and function of the interspinous ligaments?
Base to apex of each spinous process, blend with the supraspinous ligament posteriorly and the ligamentum flavum anteriorly on each side
Function - resists hyperflexion of the vertebral column
What does the subarachnoid space of the vertebral canal contain?
CSF produced in the cerebral ventricular system Arachnoid trabeculae (continuous with the pia and arachnoid mater) Large blood vessels suspended by similar strands of material which expand over the vessels to form a continuous external coat
What is the epidural space?
Space between the dura and vertebrae
What does the epidural space contain? 6
Connective tissue Fat Internal vertebral venous plexus Lymphatics Arteries Spinal nerve roots
Where does the anterior spinal artery originate, which part of the spinal cord does it supply?
Originates within the cranial cavity from vertebral arteries
Supplies the anterior portion of the spinal cord
Where do the posterior spinal arteries originate, which part of the spinal cord do they supply?
Originate in the cranial cavity arising from the posterior inferior cerebellar artery from vertebral arteries
Supply the respective ipsilateral grey and white posterior columns of the spinal cord
The anterior and posterior spinal arteries are small, what are they reinforced by? How do these enter the vertebral canal?
Reinforced by radicular branches of the intercostal and lumbar arteries which enter the vertebral canal through the intervertebral foramina
How do the intercostal arteries give rise to radicular arteries?
Posterior intercostal arteries give rise to segmental spinal arteries which give rise to anterior and posterior radicular arteries
What is the venous drainage of the spinal cord?
Veins draining the spinal cord form longitudinal channels
2 pairs of veins on each side bracket the connections of the anterior and posterior roots to the cord
Then have 1 anterior and 1 posterior spinal vein in the anterior and posterior median sulci
These veins drain into the internal vertebral plexus in the epidural space of the vertebral canal which drains into segmentally arranged vessels that connect with the major systemic veins such as the azygous vein in the thorax
At each vertebral level what other venous connections can be seen?
Connections with the thoracic, abdominal and intercostal veins and the external venous plexus
What is unusual about spinal veins?
Have no valves and blood passes directly into the systemic venous system
What is the likely path along which prostatic neoplastic cells metastasize to the CNS?
From the prostatic venous plexus to the vertebral venous plexuses as they are continuous
What 2 groups can the muscles of the back be divided into?
Deep (/intrinsic) and superficial (/extrinsic)
Extrinsic muscles of the back are innervated by what?
Ventral rami of spinal nerves (and accessory nerve)
Which 2 groups can the extrinsic muscles of the back be divided into?
Superficial and intermediate
What muscles make up the superficial extrinsic back muscles? 5
1) Rhomboid major and minor
2) Levator scapulae
3) Trapezius
4) Latissimus dorsi
What muscle make up the intermediate extrinsic back muscles?
1) Serratus posterior superior
2) Serratus posterior inferior
What is the function of serratus posterior superior and inferior?
Act as weak accessory muscles of respiration
Deep/intrinsic muscles of the back are innervated by what?
Posterior rami of the spinal nerves
Which 3 groups can the intrinsic/deep muscles of the back be divided into?
1) Superficial
2) Intermediate
3) Deep
Which muscles make up the superficial intrinsic muscles of the back?
1) Splenius capitus
2) Splenius cervicis
What are the attachments of the splenius capitus muscle?
Proximal - lower 1/2 of the ligamentum nuchae, spinous processes of C7 to T4
Distal - Mastoid process, skull below lateral 1/3 of superior nuchal line
What is the action of the splenius capitus muscle?
Together = draw head backward extending neck Individually = draw & rotate head to one side (turn face to same side)
What is the action of the splenius cervicis muscle?
Together = extend neck Individually = draw and rotate head to one side (turn face to same side)
What muscles make up the intermediate intrinsic muscles of the back?
Large erector spinae muscles that lie on each side of the vertebral column
Erector spinae consists of 3 muscles from medial to lateral
1) Spinalis
2) Longissimus
3) Iliocostalis
What is the function of erector spinae?
Chief extensor of the vertebral column
Where do the deep intrinsic muscles of the back lie?
Deep to erector spinae
Which muscles make up the deep intrinsic muscles of the back, what are the collectively called?
1) Semispinalis
2) Multifidis
3) Rotares
Called the transversospinalis group
Where do the intrinsic deep muscles of the back originate and insert?
Originate from the transverse processes of the vertebrae and insert onto the spinous processes of more superior vertebrae
How does the cervical region of the spinal cord correspond to the cervical vertebra position?
Up 1
eg. Spinal cord segment C3 lies adjacent to verterbra C2
How does the thoracic region of the spinal cord correspond to the thoracic vertebra position?
Up 2
eg. Spinal cord segment T4 lies adjacent to vertebra T2
How does the lumbar region of the spinal cord correspond to the lumbar vertebra position?
Up 3
eg. spinal cord segment L4 lies adjacent to vertebra L1
What vertebral level do the dura and arachnoid mater extend to?
S3
What is the difference between the filum terminale internus and externus?
Internus is the filum terminale within the dura and arachnoid mater, Externus extends below this
What line lies at about L4?
Intercrestal plane (between the 2 iliac crests)
What 7 layers would you have to penetrate in a lumbar puncture?
1) Supraspinous ligament
2) Interspinous ligament
3) Ligamentum flavum
4) Epidural space
5) Dura mater
6) Arachnoid mater
7) Subarachnoid space
What is the structure of the denticulate ligament and what structures does it pierce?
Pierces arachnoid and dura mater - has some free lateral edges
At what level would you perform a lumbar puncture?
L4
What is the name of the arteries supplying the spinal cord at intermediate points, coming off the aorta in the thoracic region and lumbar arteries?
Radicular arteries
What is the name of the venous plexus in the pelvis which drain straight into the internal spinal venous plexus?
Batson’s venous plexus
