Spine Flashcards
1
Q
5th Lumbar Vertebrae
A
Feature/Location:
* L5 is the largest, most inferior lumbar discovertebral unit in the vertebral column * Participates in forming the lumbar lordosis (from L1 to L5, ranging from 20 to 40°) * Components * large vertebral body with transverse width > AP diameter (kidney shaped if looking axial sections) * pedicles which project directly posteriorly * short, massive, pyramidal transverse processes * broad, thick lamina * single, short, thick spinous process which is roughly horizontal * superior and inferior articular processes with pars interarticularis between * facet joints obliquely oriented
Articulations:
* Superior articular facet with inferior articular facet of L4 * Inferior articular facet with superior articular facet of sacrum * Intervertebral discs - superior and inferior
Musculotendinous attachments:
* Psoas major (origin from transverse processes of T12-L5 and lateral aspects of IV discs) * Erector spinae muscle * Quadratus lumborum muscle (inserts into transverse processes and last rib)
Ligamentaous attachments:
* Anterior longitudinal ligament * Posterior longitudinal ligament * Ligamentum flavum * Interspinous ligament * Supraspinous ligament * Iliolumbar ligament * Lumbosacral ligament * Intertransverse ligaments
Relations:
* External vertebral venous plexus (lying within muscle) * Lumbar fascia * Thecal sac and cauda equina * Basivertebral veins and internal vertebral venous plexus
Blood supply:
* Regional/segmental lumbar arteries and veins
Variant anatomy:
* Sacralisation: assimilation of L5 to the sacrum * Limbus vertebra
2
Q
C7
A
Description/Features:
* Seventh cervical vertebra and looks like vertebrae C3-C6, but has some distinct features making it an atypical vertebrae * C7 also called vertebra prominens (long spinous process) which is easily palpable * Typical cervical features: * small, oval-sized vertebral bodies * relatively wide vertebral arch with large vertebral foramen * relatively long, bifid (except for C7) inferiorly pointing spinous processes * transverse foramina protecting the vertebral arteries and veins * anterior components: body * posterior components: lamina, pedicle, spinous process, superior and inferior articular process, transverse process * Distinct features of C7: * spinous process ends in a rounded tubercle and is not bifid * C7 transverse foramen are small, and do not transit the vertebral artery * C7 transverse process anterior tubercle is small, and is the site of attachment for scalenus pleuralis and suprapleural membrane * C8 nerve, which does not have an associated cervical vertebrae, exits in the C7-T1 vertebral foramen below C7
Articulations:
*
Intervertebral discs (superior and inferior): interposed between hyaline cartilage on the centrum of the vertebral bodies
*
C6 and T1 uncovertebral joint (Luschka’s joints): in the cervical spine, the superior surface of the vertebra below curves upward to form a hyaline covered lip that articulates with the bevelled inferior surface of the vertebra above
*
C6 and T1 facet (zygapophyseal) joint: articular processes lie at the junction of pedicle and lamina
* upper facets face obliquely up and back * lower facets face down and forward
Muscle attachments: * Trapezius * Longus colli * Middle scalene * Posterior scalene * Rhomboid minor * Semispinalis cervicis * Spinalis cervicis * Longissimus cervicis * Semispinalis capitis * Splenius capitis * Longissimus capitis * Semispinalis dorsi * Rotares * Intertransversarius * Mutlifidus * Interspinales
Ligament attachments: * Anterior longitudinal ligament * Posterior longitudinal ligament * Ligamentum flavum * Interspinous ligament * Supraspinous ligament * Nuchal ligament * Intertransverse ligaments * Sibsons's fascia
Relations:
* Inferior: C8 spinal nerve * Superior: vertebral artery, C7 spinal nerve * Intervertebral foramen: spinal cord, anterior and posterior spinal arteries, thecal sac, CSF
Arterial supply:
*
Ascending cervical artery
Variant anatomy:
* C7 may possess a cervical rib * anterior root of the transverse process attains a large size and exists as a separate bone * C7 foramen may transmit:
* posterior vertebral vein * vertebral artery * grey ramus from the inferior cervical ganglion to the anterior ramus of C7 * Hemivertebrae * Butterfly vertebrae * Block vertebrae * Bifid spinoud process * Limbus vertebrae: well-corticated osseous fragment due to herniation of the nucleus pulposus through the the vertebral body endplate
3
Q
Arterial supply of the spine
A
Description/Features:
* Spinal cord blood supply is formed by many different vessels with an extensive collateral supply and drainage * The spinal cord is supplied by three longitudinal arteries: * single anterior spinal artery: supplies the anterior two-thirds of the spinal cord * paired posterior spinal arteries: supply the posterior one-third of the spinal cord * anastomoses between the anterior and posterior spinal arteries (arterial vasocorona) supply the peripheral lateral aspect of the spinal cord (lateral columns) * Reinforcement by segmental spinal arteries -> radicular + medullary * which are branches of:
* ascending cervical artery (branch of the inferior thyroid) * deep cervical artery (branch of costocervical trunk) * intercostal arteries * lumbar arteries * lateral sacral arteries * segmental arteries pass through the intervertebral foramen and divide into anterior and posterior radicular arteries
* they have variable anastomoses with the spinal arteries * the dominant segmental artery is called the artery of Adamkiewicz * can have a variable origin and side * damage to this vessel can cause paralysis from spinal cord infarction * critical to the supply of the lumbar enlargement * If arterial supply being interrupted from the aorta (eg. surgery, trauma) collateral arterial flow can come from the internal thoracic and lateral thoracic arteries which anastomose with the posterior intercostal arteries
Variants:
* Anterior spinal artery: * origin from right vertebral only (9%) * origin from left vertebral only (3%) * origin from angle between two vertebrals (3%) * anterior spinal arteries do not fuse and travel as two separate arteries * Posterior spinal artery normally arises from the vertebral arteries adjacent to the medulla, but may arise from PICA * and origin may be intra- or extra-dural * The artery of Adamkiewicz has a variable origin (most commonly arises on the left (~80%) and at the level of T9-T10) * lumbar arteries at the level of L1 or L2 (10%) * intercostal arteries at the level of T5 to T8 (15%) * arises on the right (20%) * Variation in number of radicular branches
4
Q
Atlantoaxial joint
A
Description/Features:
* Synovial joint in the upper part of the neck between the first and second cervical vertebrae; the atlas and axis * Primary articulation which allows rotation of the head
Articular surfaces:
* There are two atlantoaxial joints: median and lateral * The median atlantoaxial joint * one between the posterior surface of the anterior arch of atlas and the front of the odontoid process * one between the anterior surface of the ligament and the back of the odontoid process * The lateral atlantoaxial joint involves the lateral mass of atlas and axis * arthrodial or gliding joint
Capsule:
* Connects the margins of the lateral masses of the atlas with margins of the posterior articular surfaces of the axis * strengthened at its posterior and medial part by an accessory ligament
Ligaments:
* Transverse ligament of the atlas: unites the medial aspects of the lateral masses * Longitudinal bands (superior and inferior): attaches to the foramen magnum and the body of the axis * together with the transverse ligament = the cruciate ligaments of the atlas * this ligament holds the anterior part of the dens against the posterior side of the anterior arch of the atlas * ALL: thick fibrous band attaches from inferior border of anterior arch of C1 to the anterior axial body * Median apical ligament and two lateral alar ligaments: connect the dens to the occipital bone * Tectorial membrane: the upward continuation of the PLL, anchored to the basilar part of the occipital bone * Posterior atlantoaxial membrane: continuation of ligamenta flava, attaches the lower border of atlantal arch to the lamina of C2 * Anterior atlantoaxial membrane * Accessory atlanto-axial ligament: connects posterior body of C2 to lateral mass of C1
Movement: * 10-15 degrees of flexion/extension * 30 degrees of axial rotation
Variants:
* Atlas
* aplasia * hypoplasia * clefts of the atlas arches * split atlas * arcuate foramen * Axis
* persistent ossiculum terminale * odontoid aplasia * os odontoideum
5
Q
C1
A
Description/Features:
* 1st cervical vertebrae * Does not have a body nor spinous process * Consists of two lateral masses connected by a short anterior and a longer posterior arch * Each lateral mass has an upper and lower facet * Vertebral foramen exists in the lateral masses, through which the vertebral artery ascends * The transverse processes are long * Anterior arch presents an anterior tubercle in front (for the anterior longitudinal ligament) and a facet posteriorly (for the dens of the axis) * Posterior arch is grooved above by the vertebral artery and the small C1 nerve on each side, and has a posterior tubercle behind
Articulations:
* Superior articular facet with occipital condyle * Posterior aspect of the anterior arch of C1 articulates with the dens * Inferior articular facet with superior articular facet of C2
Muscle attachments:
* Rectus capitis anterior * Rectus capitis lateralis * Rectus capitis posterior minor * Obliquus capitis superior * Obliquus capitis inferior * Splenius cervicis * Levator scapulae * Intertransversarius posterior cervicis * Intertransversarius anterior cervicis * Interspinalis cervicis * Longus colli
Ligament attachments:
* Anterior longitudinal ligament * Posterior longitudinal ligament / tectorial membrane * Transverse ligament - provides the most stability retaining the dens in contact with the atlas (C1) * Anterior atlanto-axial ligament * Posterior atlanto-axial ligament * Nuchal ligament * Ligamentum flavum / posterior atlanto-occipital membrane * Intertransverse ligament * Anterior atlanto-occipital membrane
Relations:
* Superior: brain stem * Inferior: C2 * Lateral: vertebral arteries and veins, * Intervertebral foramen: spinal cord, anterior and posterior spinal arteries, basivertebral veins
Arterial supply:
*
Ascending cervical artery
Variant anatomy:
* Accessory ossicle of the anterior arch of the atlas * observed as a corticated osseous density that articulates with the inferior aspect of the anterior arch of the atlas * Arcuate foramen of the atlas
* vertebral arteries pass through this foramina. * seen over the posterosuperior aspect of the atlas on lateral projections * Incomplete fusion of posterior arch * Occipital vertebrae * Atlanto-occipital assimilation
6
Q
C2
A
Description/Features:
* Axis is the second cervical vertebra and is an atypical cervical vertebra * Prominent feature is the odontoid process (which is embryologically the body of the atlas) * Important role in rotation of the head - majority of movement occurring around the dens and at the atlanto-axial joint * Five primary and two secondary ossification centres * Body with the attached dens, two lateral masses, a posterior neural arch (formed by the pedicle and a thick lamina), and a large spinous process, which is commonly bifid * Components: body, lateral mass, superior and inferior articular processes, pars interarticularis, transverse process, transverse foramen, lamina, pedicle, spinous process * Typical cervical features: * relatively wide vertebral arch with large vertebral foramen * transverse foramina protecting the vertebral arteries and veins * ADI < 3 mm in adults and < 5 mm in childrens * BDI < 12 mm in adults
Articulations:
*
Superior articular facet with inferior articular face of C1
*
Dens articulates with the posterior aspect of the anterior arch of C1
*
Inferior articular facet with superior articular facet of C3
*
Uncovertebral articulation (Luschka’s joints) with C3
*
Intervertebral discs (inferior): interposed between hyaline cartilage on the centrum of the vertebral bodies
Muscle attachments:
* Semispinalis cervicis * Obliquus capitis inferior * Rectus capitis posterior major * Longus colli * Levator scapulae * Rotatores * Intertransversarius * Interspinales * Middle scalene
Ligament attachments:
*
Anterior longitudinal ligament
*
Cruciate ligaments - superior and inferior longitudinal bands
*
Transverse ligament - provides the most stability retaining the dens in contact with the atlas (C1)
*
Apical ligament - embryological remnant of the notochord, anchors dens to occipital bone
*
Alar ligament - anchors dens to occipital bone
*
Accessory ligament
*
Posterior atlanto-axial ligament (ligamentum flavum)
*
Tectorial membrane (posterior longitudinal ligament)
*
Interspinous ligament
*
Nuchal ligamentum
*
Intertransverse ligaments
Relations:
* Superior: brain stem * Inferior: C3 * Lateral: vertebral arteries and veins, * Intervertebral foramen: spinal cord, anterior and posterior spinal arteries, basivertebral veins
Arterial supply:
*
Ascending cervical artery
Variant anatomy:
* Hypoplasia * Aplasia (rare) * Single spinous process * Os odontoideum
* separation of the odontoid process from the body of the axis * two main types * orthotopic: normal position with a wide gap between C2 and os odontoideum * dystopic: displaced * Persistent ossiculum terminale * ossiculum terminale appears as a secondary ossification centre between 3-6 years and normally fuses by 12 years * failure of fusion results in a persistent ossiculum terminale * small, well-corticated ossicle at the tip of the dens
7
Q
Cauda Equina
A
Description/Features:
* Bundle of spinal nerves and spinal nerve roots, consisting of L2-S5 spinal nerves and the coccygeal nerve * All these spinal nerves originate in the conus medullaris (tapered lower end of the spinal cord) * Spinal cord stops growing in infancy but vertebral column continues to grow * The top end of the nerve stays attached to the spinal cord while the lower end of the nerve exits the spinal column at its proper level * End of the spinal cord is usually at the level of L1 * Cauda equina exists within the lumbar cistern (space formed from the surrounding dural sac) * CSF is drawn from this space during a lumbar puncture
Supply:
* Pelvic organs * Lower limbs * Motor innervation of the internal and external anal sphincters * Sensory innervation of the perineum * Partially parasympathetic innervation of the bladder
Arterial supply:
* Anterior and posterior spinal arteries * Iliolumbar and lateral sacral arteries anastomose with spinal arteries
Venous drainage:
* Anterior and posterior spinal veins (communicates with the internal vertebral plexus located in the epidural space) * Anterior and posterior radicular veins
Relations:
* Anterior: vertebral bodies (L2-L5), sacrum, coccyx, intervertebral discs, anterior spinal artery * Lateral: pedicles, facet joints * Posterior: spinous processes, posterior spinal arteries
Variation:
*
Spinal cord may end anywhere between T12 and L3
8
Q
Spinal Cord
A
Description/Features:
* Spinal cord is the part of the CNS that is found within the central canal of the vertebral column * Divided into cervical, thoracic and lumbar parts and ends at the conus medullaris (approximately L1 level) * 31 segmental nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal * C1-C7 arise above pedicle of the corresponding vertebra, rest arise below pedicle of corresponding vertebra * Spinal nerve is formed by the dorsal and ventral roots * dorsal root is afferent sensory (cell body in the DRG), ventral root is efferent motor (cell body close to target tissue) * Expansions of the cord occur at C5 - T1 due to the brachial plexus, and L2 - S3 due to the lumbosacral plexus * Nerve roots that exit below the conus at L1/L2 are called the cauda equina * 3 layers of meninges surround the cord: the pia, arachnoid and dura mater * 21 pairs of denticulate ligaments attach the pia mater of the cord to the arachnoid and dura mater of the sac * Anterior median fissure dips into it anteriorly, posterior median sulcus exists posteriorly * Central canal is filled with CSF * Grey matter is central (dorsal, lateral and ventral horns) * White matter is peripheral and has spinal cord tracts (dorsal, lateral and ventral columns)
Begins:
* Foramen magnum (continuous with the medulla oblongata)
Ends:
* Conus medullaris (level of L1 or L2) * Cord continues as a prolongation of pia mater (filum terminale)
Arterial supply:
* Posterior spinal arteries * Anterior spinal artery * Segmental supply from ascending cervical, intercostal and lumbar arteries * Artery of Adamkiewicz: critical to the supply of the lumbar enlargement (usually from left side, T8-L1)
Venous drainage:
* Anterior and posterior spinal veins --> internal vertebral venoux plexus --> external vertebral venous plexus --> regional veins
* Neck: vertebral veins * Thorax: azygos veins * Lumbar: lumbar veins
Variant anatomy:
* Spinal dysraphism * includes neural tube defects:
* incomplete closure of the neural tube in very early pregnancy * spina bifida * anencephaly * categorised into two groups
* open spinal dysraphism: meningocele, myelomeningocoele * closed spinal dysraphism * Tethered cord * Spinal cord may end at a variable level
9
Q
Epidural space
A
Description:
* The spinal epidural space is located between the spinal dura mater and the vertebral column * It extends from the foramen magnum to the sacral canal at the level of S2-S3
Boundaries: * Inner: spinal dura mater * Outer: PLL, neural arches/intervertebral foramen, ligamentum flavum
Contents: * Loose areolar connective tissue * Fat * Vertebral venous plexus * Lymphatics * Radicular arteries * Spinal nerve roots
10
Q
Facet Joint
A
Description/Features:
* Synovial joints that have a fibrous capsule and connect the articular facets of the vertebrae * Facet joints are situated between the pedicle and lamina of the same vertebra and form the articular pillars that act to provide structural stability * Articular surfaces have different orientations in the various vertebral regions * Cervical Region = 45 degrees; frontal plane; all movements are possible such as flexion, extension, lateral flexion, and rotation * Thoracic Region = 60 degrees; frontal plane; lateral flexion and rotation; no flexion/extension * Lumbar Region = 90 degrees; sagittal plane; only flexion and extension
Articular surfaces:
* Hyaline covered * Superior facet of the lower vertebra articulates with the interior facet of the vertebra above
Capsule:
* Fibrous articular capsule
Ligaments:
* Posterior ligamentous complex acts to hold the facet joints of the neighbouring vertebrae in fixed relation with each other
* ligamentum flavum * interspinous ligament * supraspinous ligament * fibrous joint capsule is including in posterior ligamentous complex
Relations:
* Structures that pass through the intervertebral foramen
* spinal nerve * dorsal root ganglion * spinal artery of the segmental artery * communicating veins between the internal and external plexuses * meningeal (sinu-vertebral) nerves * transforaminal ligaments
Nerve Supply:
* Meningeal branch of the spinal nerve
Blood Supply:
* Cervical Area - Ascending Cervical Artery and Spinal branch from Verterbral Arteries * Thoracic - Posterior Intercostal Arteries * Lumbar - Lumbar Arteries
11
Q
Intervertebral Joint
A
Description/Features:
*
Intervertebral discs are located between the vertebral bodies
*
Account for approximately 25% of the total height of the vertebral column
*
Decreases with age as disc height is lost
*
Greater thickness anteriorly contributes to the normal cervical and lumbar lordosis
*
Each intervertebral disc is comprised of:
* peripheral annulus fibrosus * central nucleus pulposus * L4/5 and L5/S1 most prone to herniation * Embryology: notochord becomes the nucleus pulposus
Relations:
* Above and below the intervertebral disc are the vertebral body endplates * Posterior spinal nerve * Anterior spinal artery * ALL, PLL * Anterior: muscles/organs at that particular level
Supply:
* Inner layers of the annulus fibrosus and nucleus pulposus have neither innervation nor blood supply * receives nutrition via diffusion across the vertebral body endplates * outer fibres of the annulus fibrosus are innervated by sinuvertebral nerves arising from the dorsal root ganglia
12
Q
Ligaments of the lumbar spine
A
Description/Features:
* Spinal ligaments essential in keeping joints between vertebrae congruent / strong
Ligaments/Course:
* Anterior longitudinal ligament (ALL): arises from anterior tubercle of the atlas, travels downwards, anterior to the vertebral body (firmly united to the periosteum) and discs (attaching to the anterior annulus), attaches to the front of the upper part of the sacrum; it broadens as it travels downward * Posterior longitudinal ligament (PLL): arises from the back of the axis (C2) body, travels downward posterior to the vertebral body (attached loosely) and discs (firmly attaching to the posterior annulus), attaching to the back of the sacrum; narrows as it travels downward * Ligamentum flavum: yellowish, elastic ligament, runs between adjacent laminae (front of the upper lamina to the back of the lower lamina); in the lumbar region, it runs laterally, covering the anterior aspect of the facet joints * Interspinous ligaments: join spinous processes along adjacent borders, relatively weak fibrous tissue that fuses with supraspinous ligaments * Supraspinous ligaments: join tips of adjacent spinous processes, strong bands of fibrous tissue * Intertransverse ligaments: join transverse processes along adjacent borders, relatively weak fibrous tissue * Iliolumbar ligaments: strong band of connective tissue which courses from the transverse process of L5 to the posterior iliac wing and iliac crest; it functions to maintain the alignment of L5 on the sacrum during various movements * Lumbosacral ligament
13
Q
Lumbar variants
A
Lumbar rib
* Rib coming off L1 * Mostly an asymptomatic incidental finding
Block vertebrae
* Failure of separation of two or more adjacent vertebral bodies
Butterfly vertebrae
* Failure of fusion of the lateral halves of the vertebral body
Hemivertebrae
* Lack of formation of one half of a vertebral body * Hemivertebra acts as a wedge within the vertebral column * Common cause of a congenital scoliosis/kyphosis or a lordosis
Spondylolysis
* Defect in the pars interarticularis of the neural arch, the portion of the neural arch that connects the superior and inferior articular facets * Commonly known as pars defect
Lumbarisation of S1
* Assimilation of S1 to lumbar spine * Less common than sacralisation ~2% * Presence of six rib-free lumbar-type vertebrae, which may have the following features
* squaring of highest sacral (transitional) vertebra * facet joints (even rudimentary) * intervertebral disc between S1 and S2 * Iliolumbar ligament defines L5 (attaches transverse process to iliac crest)
Sacralisation of L5
* Assimilation of L5 to the sacrum * More common than lumbarisation ~17% * Presence of four rib-free lumbar type vertebrae, which may have the following features
* wedging of the lowest lumbar (transitional) vertebra * hypoplastic or absent facet joints or intervertebral disc
14
Q
Meninges and meningeal spaces
A
Description/Features:
* Three layers of meninges cover the spinal cord - dura, arachnoid and pia mater * Dura mater * extends from the foramen magnum to the sacrum and coccyx * attached to the foramen magnum and the periostium covering the uppermost cervical vertebrae * remainder of the vertebral canal, the dura is not attached to the vertebrae, being separated by the epidural space * Arachnoid mater
* invests the spinal cord loosely * continuous with the cerebral arachnoid above * traverses the foramen magnum and descends to around the S2 vertebral level (spinal cord ends at ~L2) * Pia mater
* much thicker than cerebral pia mater (two layers in the spine) * invests the spinal cord closely * ensheathes the anterior and posterior spinal arteries * enters the anterior median fissure * laterally, the pia forms 21 pairs of denticulate ligaments which attaches to the arachnoid and dura on each side * inferiorly the pia is thickened as the filum terminale, which continues into the sacrum and fuses with the dura mater
Spaces:
* Epidural space * contains fat and the internal vertebral venous plexus * Subdural space * potential space between dura and arachnoid, has no contents * Subarachnoid space * wide interval which contains CSF
15
Q
Trapezius
A
Origin:
* External occipital protuberance * Nuchal ligament * Medial superior nuchal line * Spinous processes of vertebrae C7-T12
Insertion:
* Posterior border of the lateral third of the clavicle * Acromion process * Spine of scapula
Artery:
*
Transverse cervical artery
Innervation: * Accessory nerve (motor) * Cervical spinal nerves C3 and C4 (motor and sensation)
Actions:
* Rotation, retraction, elevation, and depression of scapula
Relations:
* Anterior border forms the posterior margin of the posterior triangle * Shares insertion with the deltoid
