Week 1 SAQs - Vertebral Column Anatomy PDF

# Vertebral Column Anatomy ## Introduction ### What are the primary ossification centres of a vertebra? - Centrum (unpaired) - Neural arches (paired) - Costal elements (variable fusion or rib formation) ### What role do blood vessels play in vertebral segmentation? Blood vessels from the aorta...

# Vertebral Column Anatomy ## Introduction ### What are the primary ossification centres of a vertebra? - Centrum (unpaired) - Neural arches (paired) - Costal elements (variable fusion or rib formation) ### What role do blood vessels play in vertebral segmentation? Blood vessels from the aorta form between somites, driving segmentation by providing nourishment to developing vertebrae. ### What structural changes occur during the cartilaginous stage of development? Hyaline cartilage replaces mesenchyme, forming the annulus fibrosus and nucleus pulposus in intervertebral discs. ### What is block vertebra, and how does it form? Block vertebra occurs when segmentation fails, leading to fused vertebrae with obliterated intervertebral discs. ### What developmental process results in butterfly vertebrae? Failure of ossification of lateral cartilage centres results in butterfly vertebrae with a split vertebral body. ### How do costal elements differ in the thoracic and lumbar regions? - **Thoracic region:** costal elements form ribs - **Lumbar region:** costal elements contribute to transverse processes ### What is the significance of interlaminar and neurocentral cartilage in vertebral growth? They allow vertebral growth during childhood and fuse around 6-8 years of age. ### How do vertebral elements vary between cervical, thoracic, and lumbar regions? - **Cervical:** Transverse foramina and bifid processes - **Thoracic:** Rib facets - **Lumbar:** Large vertebral bodies and interlocking facets ### What are the clinical implications of reduced notochordal cells during development? Reduced notochordal cells lead to poor nucleus pulposus development, contributing to disc degeneration and block vertebrae. ## Intervertebral Discs ### What is the role of the annulus fibrosus and nucleus pulposus in intervertebral discs? - **Annulus fibrosus:** provides tensile strength - **Nucleus pulposus:** absorbs compressive forces ### Why are intervertebral discs thinner in adults compared to infants? Water content decreases with age, reducing disc height and elasticity. ### What is the relationship between vertebral growth plates and secondary ossification centres? Growth plates remain active until early adulthood, and secondary ossification centres form processes like spinous and transverse processes. ### How do Hox genes regulate vertebral region differentiation? Hox genes control the expression of region-specific features, such as ribs in thoracic vertebrae and transverse foramina in cervical vertebrae. ## Vertebral Regions ### Is the cervical vertebra dorsal or ventral? The cervical vertebra, like all vertebrae, has both dorsal and ventral components; the ventral aspect refers to the vertebral body, while the dorsal aspect includes the neural arch and processes. ### Is the thoracic vertebra pre-axial or post-axial? The thoracic vertebra is considered post-axial, as it is located posterior to the embryonic notochord. ### Name the features of the lumbar vertebra. - Large kidney-shaped vertebral bodies - Short spinous processes - Articular facets oriented medially and laterally to allow flexion and extension ### Which nerve supplies the zygapophyseal joints in the cervical region? The cervical zygapophyseal joints are supplied by the medial branches of the dorsal rami of spinal nerves. ### A lesion to which spinal nerve would produce pain in the thoracic intercostal space? Describe the clinical presentation. A lesion to a thoracic spinal nerve, such as T5, could result in intercostal neuralgia; presenting as radiating pain in the intercostal space corresponding to the nerve's dermatome. ### Aside from generic trauma, what is a common injury mechanism causing disc herniation in the lumbar region? Repetitive axial loading and improper lifting mechanics often lead to disc herniation in the lumbar region, typically between L4 and L5 or L5 and S1. ### Name a common action of the multifidus and rotatores muscles in the lumbar region. Both the multifidus and rotatores contribute to stabilisation and rotation of the lumbar vertebral column. ### Which vertebral element forms the transverse processes in the thoracic region? In the thoracic region, the transverse processes are formed from costal elements that later develop ribs. ### Through which space does the spinal nerve exit the lumbar vertebral column? The spinal nerves exit through the intervertebral foramina, bounded by adjacent vertebral pedicles and zygapophyseal joints. ### What are the boundaries and contents of the cervical transverse foramina? - **Boundaries:** Surrounding transverse processes - **Contents:** Vertebral artery and vein (C6 to C1) and accompanying sympathetic plexus ### Name a movement in the sagittal plane allowed at the thoracic vertebral column. Flexion occurs in the sagittal plane of the thoracic vertebral column; though it is limited by rib attachments. ### What is the bilateral action of the erector spinae muscles in the thoracic region? The erector spinae muscles extend the thoracic vertebral column when acting bilaterally. ### What is the most distal joint influenced by the sacral vertebrae? The most distal joint influenced by the sacral vertebrae is the sacroiliac joint. ### Which joint in the thoracic region does not allow rotation? The costovertebral joints restrict rotation in the thoracic region due to rib attachments. ### Which movement does the anterior longitudinal ligament restrict in the cervical spine? The anterior longitudinal ligament restricts hyperextension in the cervical spine. ### Which muscles attach to the spinous processes of thoracic vertebrae? - Trapezius - Rhomboid major - Latissimus dorsi ### Movements in which planes are permissible at the cervical vertebrae? - **Sagittal:** Flexion and extension - **Frontal:** Lateral flexion - **Transverse:** Rotation ### What type of contraction does the erector spinae perform during forward flexion of the thoracic spine? The erector spinae performs eccentric contraction during forward flexion to control the descent. ### How many segments does a sacral vertebra originally consist of before fusion? A sacral vertebra originally consists of five segments before fusing into a single sacrum. ### Which vertebral region is characterised by ribs articulating with transverse processes? The thoracic vertebral region is characterized by rib articulation with the transverse processes. ### Is the cervical vertebra dorsal or ventral? The cervical vertebra has both dorsal (neural arch) and ventral (vertebral body) components. ### Is the thoracic vertebra dorsal or ventral? The thoracic vertebra has dorsal (neural arch) and ventral (vertebral body) components. ### Is the lumbar vertebra dorsal or ventral? The lumbar vertebra has dorsal (neural arch) and ventral (vertebral body) components. ### Is the sacral vertebra dorsal or ventral? The sacral vertebra has both dorsal (neural arch) and ventral (vertebral body) components. ### Is the cervical vertebra pre-axial or post-axial? The cervical vertebra is post-axial; posterior to the notochord. ### Is the thoracic vertebra pre-axial or post-axial? The thoracic vertebra is post-axial; posterior to the notochord. ### Is the lumbar vertebra pre-axial or post-axial? The lumbar vertebra is post-axial; posterior to the notochord. ### Is the sacral vertebra pre-axial or post-axial? The sacral vertebra is post-axial; posterior to the notochord. ### Describe the cervical vertebra. - Small, oval body - Transverse foramina - Bifid spinous processes ### Describe the thoracic vertebra. - Heart-shaped body - Costal facets - Long, downward-sloping spinous processes ### Describe the lumbar vertebra. - Large, kidney-shaped body - Short spinous processes - Interlocking articular facets ### Describe the sacral vertebra. The sacral vertebrae are fused to form the sacrum, providing a stable base for the spine and transmitting weight to the pelvis. ### Which nerve supplies the intertransversarii muscles in the cervical region? The ventral rami of cervical spinal nerves supply the intertransversarii muscles. ### Which nerve supplies the intertransversarii muscles in the lumbar region? The dorsal and ventral rami of lumbar spinal nerves supply the intertransversarii muscles. ### A lesion to which nerve would produce the observed clinical sign involving the cervical vertebra? Describe the positioning at joints. A lesion to the cervical spinal nerves may cause weakness or sensory deficits at the intervertebral joints between cervical vertebrae. ### A lesion to which nerve would produce the observed clinical sign involving the lumbar vertebra? Describe the positioning at joints. A lesion to the lumbar spinal nerves may cause motor and sensory deficits at the intervertebral joints between lumbar vertebrae. ### Aside from generic trauma, what is a common injury mechanism for the cervical vertebrae? Hyperextension injuries, such as whiplash, are common in the cervical vertebrae. ### Aside from generic trauma, what is a common injury mechanism for the lumbar vertebrae? Repetitive axial loading or improper lifting can cause disc herniation in the lumbar vertebrae. ### Name a common action of the multifidus and erector spinae muscles. Both stabilise the spine and assist in extension. ### Name a common action of the intertransversarii and interspinales muscles. Both assist in vertebral stabilisation and fine-tune movements. ### Which segment of the paraxial mesoderm contributes to the cervical vertebrae? The sclerotome from cervical somites contributes to the cervical vertebrae. ### Which segment of the paraxial mesoderm contributes to the lumbar vertebrae? The sclerotome from lumbar somites contributes to the lumbar vertebrae. ### Which space does the spinal nerve exit the cervical vertebral column? The spinal nerve exits through the intervertebral foramen. ### Which space does the spinal nerve exit the lumbar vertebral column? The spinal nerve exits through the intervertebral foramen. ### What are the boundaries/contents of the cervical transverse foramen? - **Boundaries:** Transverse processes - **Contents:** Vertebral artery and vein, and sympathetic plexus ### What are the boundaries/contents of the intervertebral foramen in the thoracic region? - **Boundaries:** Superior and inferior notches, vertebral body, and zygapophyseal joints - **Contents:** Spinal nerves and dorsal root ganglia ### Name a sagittal plane movement of the cervical vertebrae. Flexion and extension occur in the sagittal plane. ### Name a sagittal plane movement of the lumbar vertebrae. Flexion and extension occur in the sagittal plane. ### What is the unilateral action of the erector spinae in the thoracic region? Lateral flexion of the thoracic vertebrae. ### What is the bilateral action of the multifidus in the lumbar region? Extension of the lumbar vertebrae. ### What is the most distal joint influenced by the sacral vertebrae? The sacroiliac joint is the most distal joint influenced. ### Which joint of a vertebra does the anterior longitudinal ligament perform no action on? The anterior longitudinal ligament does not act on the atlanto-occipital joint. ### Which movement can the posterior longitudinal ligament prevent/restrict/control? The posterior longitudinal ligament restricts hyperflexion. ### Which of the pinned muscles is most likely to be challenged by active/passive insufficiency during rotation? The multifidus is most likely to be challenged. ### Which muscles attach at the transverse processes of the thoracic vertebrae? - Levator costarum - Longissimus - Intertransversarii ### Movements in which cardinal planes are permissible at cervical vertebrae? - **Sagittal:** Flexion and extension - **Frontal:** Lateral flexion - **Transverse:** Rotation ### What movement occurs through the sagittal plane at the thoracic vertebrae during flexion? Flexion occurs, reducing the angle between vertebrae. ### What type of muscle contraction does the multifidus perform during extension of the vertebral column? The multifidus performs concentric contraction. ### How many vertebral segments does the multifidus cross in the lumbar spine? The multifidus crosses 3–4 vertebral segments in the lumbar spine. ### How many vertebral segments does the semispinalis cross in the cervical region? The semispinalis crosses 5–6 vertebral segments in the cervical region. ### Which vertebral region is the lumbar vertebrae most prone to degeneration? The lumbar region is the most prone to degeneration. ### Which vertebral region is the cervical vertebrae most affected by trauma? The cervical region is most affected by trauma. ### Which vertebral element is the transverse foramen derived from? The transverse foramen is derived from the costal element of cervical vertebrae. ### Which vertebral element is the spinous process derived from? The spinous process is derived from the neural arch. ## Movements of the Vertebral Column ### Which movements are favoured/NOT possible between vertebrae in the cervical region? - **Favoured:** Flexion, extension, lateral flexion, and rotation - **NOT possible:** None; cervical vertebrae allow all movements. ### Which movements are favoured/NOT possible between vertebrae in the thoracic region? - **Favoured:** Rotation - **NOT possible:** Significant lateral flexion due to rib attachments ### What evolutionary changes allowed mammals to develop true lumbar vertebrae, and how does this affect their movement compared to amphibians and reptiles? Mammals developed true lumbar vertebrae as limbs rotated under the body, enabling flexion-extension for galloping, unlike amphibians and reptiles; which rely on lateral undulation. ### How do the shapes of the vertebral bodies differ between cervical, thoracic, and lumbar regions, and what functional significance do these differences have? - **Cervical:** Small, oval for flexibility - **Thoracic:** Heart-shaped with rib facets for stability - **Lumbar:** Large, kidney-shaped for weight-bearing ### What is the functional role of the zygapophyseal joints in limiting or permitting specific movements in the lumbar spine? Zygapophyseal joints in the lumbar spine prevent rotation while permitting flexion and extension due to their interlocked radial orientation. ### How does the orientation of the thoracic articular facets affect rotational movement, and why is lateral flexion constrained in this region? Thoracic facets are tangential, allowing rotation but limiting lateral flexion due to rib attachments. ### What are the structural differences between the anterior and posterior components of the motion segment, and how do these differences influence their respective functions? - **Anterior:** Vertebral bodies and discs, load-bearing - **Posterior:** Neural arch and ligaments, motion control ### How does the intervertebral disc respond to axial compression, and what are the consequences of weakening in the annulus fibrosus? Discs transmit loads via nucleus pulposus pressure. Weakening in the annulus fibrosus leads to disc herniation or bulging. ### What anatomical features allow for coupled movements in the cervical vertebrae, and how does this impact neck mobility? Oblique facet angles (45°) allow coupled lateral flexion and rotation, increasing mobility. ### How do Hox genes influence the morphological differences between vertebral regions, and what are some examples of region-specific features they regulate? Hox genes regulate segmentation and feature development, such as transverse foramina in cervical vertebrae and rib facets in thoracic vertebrae. ### Describe the changes in intervertebral disc composition with ageing, and explain how these changes affect vertebral column mechanics and height. Water content decreases with age, reducing disc elasticity and height, leading to reduced shock absorption. ### What binary features can be used to definitively identify a vertebra as cervical, thoracic, lumbar, or sacral? - **Cervical:** Transverse foramina - **Thoracic:** Rib facets - **Lumbar:** Absence of both - **Sacral:** Fused vertebrae ### What mechanisms lead to vertebral injuries such as disc herniation or spondylolisthesis, and how are these injuries region-specific? - **Disc herniation:** Axial loading in lumbar spine - **Spondylolisthesis:** Hyperextension injuries in lumbar or cervical spine ## Curvature of the Vertebral Column ### How does the curvature of the vertebral column (e.g., lordosis and kyphosis) develop, and what functional advantages do these curvatures provide? Lordosis and kyphosis develop postnatally for shock absorption and weight distribution. ### What is the relationship between vertebral morphology and injury mechanisms such as whiplash in the cervical spine or hyperextension injuries in the lumbar spine? - **Cervical spine:** Mobile facets predispose to whiplash - **Lumbar spine:** Load-bearing predisposes to hyperextension injuries. ### Explain how the nucleus pulposus and annulus fibrosus work together to maintain intervertebral disc function under load. Nucleus absorbs pressure, and annulus resists tension to maintain disc integrity under load. ### Why do the lumbar vertebrae have a greater range of flexion and extension compared to rotation, and how does this relate to facet joint orientation? Lumbar facets are interlocked radially, permitting flexion-extension but restricting rotation. ### What are the consequences of sacral vertebrae fusion on pelvic stability and lower limb biomechanics? Fusion stabilises the pelvis, enabling force transfer to the lower limbs. ### How do coupled movements (e.g., lateral flexion with rotation) vary between cervical, thoracic, and lumbar regions, and what anatomical features facilitate or constrain these movements? - **Cervical:** Coupled due to oblique facets - **Thoracic:** Limited by ribs - **Lumbar:** Minimal due to interlocked facets ### Describe the relationship between the anterior longitudinal ligament and posterior longitudinal ligament in maintaining vertebral column stability. The anterior ligament resists hyperextension, while the posterior ligament resists hyperflexion. ### What adaptations are present in aquatic mammals' vertebral columns that differentiate them from terrestrial mammals? Flattened cervical vertebrae and retained lumbar regions for aquatic locomotion. ### How do the load-bearing capacities of the cervical, thoracic, and lumbar vertebrae differ, and what structural features enable these capacities? - **Cervical:** Lightweight for flexibility - **Thoracic:** Rib attachments for stability - **Lumbar:** Large vertebral bodies for weight-bearing ## Ligaments of the Vertebral Column ### Is the ligamentum flavum dorsal or ventral? The ligamentum flavum is dorsal; located posterior to the spinal cord. ### Is the anterior longitudinal ligament dorsal or ventral? The anterior longitudinal ligament is ventral; running along the anterior surface of the vertebral bodies. ### Is the posterior longitudinal ligament dorsal or ventral? The posterior longitudinal ligament is dorsal; located on the posterior aspect of the vertebral bodies within the vertebral canal. ### Is the supraspinous ligament dorsal or ventral? The supraspinous ligament is dorsal; running along the tips of the spinous processes. ### Is the ligamentum flavum pre-axial or post-axial? The ligamentum flavum is post-axial. ### Is the anterior longitudinal ligament pre-axial or post-axial? The anterior longitudinal ligament is pre-axial. ### Is the posterior longitudinal ligament pre-axial or post-axial? The posterior longitudinal ligament is pre-axial. ### Is the supraspinous ligament pre-axial or post-axial? The supraspinous ligament is post-axial. ### Describe the ligamentum flavum. The ligamentum flavum is an elastic ligament connecting the laminae of adjacent vertebrae. ### Describe the anterior longitudinal ligament. The anterior longitudinal ligament is a broad, strong ligament running along the anterior vertebral bodies, preventing hyperextension. ### Describe the posterior longitudinal ligament. The posterior longitudinal ligament is a narrow ligament along the posterior vertebral bodies, restricting hyperflexion. ### Describe the supraspinous ligament. The supraspinous ligament connects the tips of the spinous processes, continuing as the ligamentum nuchae in the cervical region. ### Which nerve supplies the erector spinae muscles? The dorsal rami of mixed spinal nerves supply the erector spinae muscles. ### Which nerve supplies the semispinalis capitis muscle? The dorsal rami of cervical spinal nerves supply the semispinalis capitis muscle. ### Which nerve supplies the rectus capitis posterior major? The dorsal ramus of C1 (suboccipital nerve) supplies the rectus capitis posterior major. ### Which nerve supplies the obliquus capitis inferior? The dorsal ramus of C1 (suboccipital nerve) supplies the obliquus capitis inferior. ### A lesion to which nerve would produce the observed clinical sign involving the ligamentum flavum? Describe the positioning at joints. A lesion to the spinal nerve roots compressed by a buckling ligamentum flavum may cause radiculopathy at the corresponding intervertebral foramen. ### A lesion to which nerve would produce the observed clinical sign involving the rectus capitis posterior major? Describe the positioning at joints. A lesion to the dorsal ramus of C1 would impair extension and ipsilateral rotation at the atlanto-occipital and atlantoaxial joints. ### Aside from generic trauma, what is a common injury mechanism for lesions to the posterior longitudinal ligament? Chronic hyperflexion or herniated intervertebral discs may stress or compress the posterior longitudinal ligament. ### Aside from generic trauma, what is a common injury mechanism for lesions to the ligamentum flavum? Degenerative thickening of the ligamentum flavum may compress spinal nerve roots, causing radiculopathy. ### Name a common action of the rotatores and multifidus muscles. Both resist rotational movement and stabilise the vertebral column. ### Name a common action of the semispinalis capitis and erector spinae muscles. Both extend the vertebral column and head. ### Name a common action of the rectus capitis posterior major and obliquus capitis inferior muscles. Both perform ipsilateral rotation of the head and neck. ### Which space does the anterior longitudinal ligament pass through along the vertebral column? The anterior longitudinal ligament passes along the anterior surface of the vertebral bodies. ### Which space does the posterior longitudinal ligament pass through along the vertebral column? The posterior longitudinal ligament runs within the vertebral canal along the posterior vertebral bodies. ### What are the boundaries/contents of the suboccipital triangle? - **Boundaries:** Rectus capitis posterior major, obliquus capitis superior, obliquus capitis inferior. - **Contents:** Vertebral artery and dorsal ramus of C1. ### What are the boundaries/contents of the intervertebral foramen? - **Boundaries:** Adjacent pedicles, vertebral bodies, and zygapophyseal joint. - **Contents:** Spinal nerve roots and dorsal root ganglia. ### Movements in which cardinal planes are permissible at the thoracic vertebral column? - **Sagittal:** Flexion and extension - **Frontal:** Lateral flexion - **Transverse:** Rotation ### Movements in which cardinal planes are permissible at the cervical vertebral column? - **Sagittal:** Flexion and extension - **Frontal:** Lateral flexion - **Transverse:** Rotation ### What type of muscle contraction does the erector spinae perform during flexion of the thoracolumbar spine? The erector spinae performs eccentric contraction during flexion to control movement. ### What type of muscle contraction does the semispinalis capitis perform during extension of the cervical spine? The semispinalis capitis performs concentric contraction during extension. ### How many vertebral segments does the multifidus cross in the lumbar spine? The multifidus crosses 3–4 vertebral segments in the lumbar spine. ### How many vertebral segments does the semispinalis cross in the thoracic region? The semispinalis crosses 5–6 vertebral segments in the thoracic region. ### Which vertebral region is the semispinalis primarily found in? The semispinalis is primarily found in the cervical and thoracic regions. ### Which vertebral region is the multifidus most developed in? The multifidus is most developed in the lumbar region. ### Which movements are favoured/NOT possible between vertebrae in the thoracic region? - **Favoured:** Rotation - **NOT possible:** Significant lateral flexion due to rib constraints. ### Which movements are favoured/NOT possible between vertebrae in the lumbar region? - **Favoured:** Flexion and extension. - **NOT possible:** Significant rotation due to interlocking facet joints ### What are the roles of the multi-segmental ligaments in the vertebral column? - **Anterior longitudinal ligament:** prevents hyperextension - **Posterior longitudinal ligament:** prevents hyper-flexion - **Supraspinous ligament:** stabilises spinous processes ### How does the ligamentum flavum differ from the other multi-segmental ligaments? The ligamentum flavum is highly elastic, preventing buckling during flexion and avoiding compression of the spinal cord. ### What is the significance of the zygapophyseal joint capsular ligaments? They stabilise the facet joints, restrict excessive movement, and protect the joint capsules. ### Which intrinsic muscles are most sensitive to length changes? The intertransversarii and interspinous muscles have a high density of muscle spindles, making them highly sensitive to length changes. ### What is the primary function of the transversospinales muscle group? The transversospinales group, including the rotatores, multifidus, and semispinalis, primarily resists rotational movements and stabilises the vertebral column. ### Why are the multifidus muscles more prominent in the lumbar region? The multifidus muscles stabilise the lumbar spine during weight-bearing and prevent excessive movement. ### What is the clinical relevance of the suboccipital triangle? The suboccipital triangle contains the vertebral artery and dorsal ramus of C1, structures that are critical for head movement, proprioception, and circulation. ### What are the functions of the rectus capitis posterior major and minor muscles? - **Rectus capitis posterior major:** performs extension and ipsilateral rotation of the head. - **Rectus capitis posterior minor:** performs extension. ### How does the thoracolumbar fascia contribute to the stability of the lumbar spine? The thoracolumbar fascia forms a dense sheath reinforced by the latissimus dorsi and gluteus maximus, providing stability during movement and weight-bearing. ### What are the three layers of the thoracolumbar fascia, and what do they enclose? - **Anterior:** Covers the quadratus lumborum. - **Middle:** Lies between the quadratus lumborum and the erector spinae. - **Posterior:** Covers the erector spinae and transversospinales. ### What is the functional difference between intrinsic and extrinsic back muscles? - **Intrinsic muscles:** stabilise and move the spine and are innervated by dorsal rami. - **Extrinsic muscles:** are limb-associated and innervated by ventral rami. ### Which extrinsic muscles attach to the thoracolumbar fascia? - Serratus posterior superior - Serratus posterior inferior ### What distinguishes extrinsic from intrinsic back muscles? Extrinsic muscles are innervated by ventral rami and are outside the thoracolumbar fascia, while intrinsic muscles are innervated by dorsal rami and within it. ### What is the action of the multifidus muscle in the lumbar region? Stabilisation and resistance to rotational movement. ### What is the function of the splenius capitis muscle? Extension, lateral flexion, and ipsilateral rotation of the head and neck. ### Which muscles are primarily responsible for resisting rotational movement in the thoracic spine? Rotatores and multifidus muscles. ### How does the thoracic spine accommodate breathing through soft tissues The thoracolumbar fascia in the thoracic region is thin and flexible to accommodate rib movement during breathing. ### Which ligament replaces the supraspinous ligament in the cervical region? The ligamentum nuchae. ### What is the function of the zygapophyseal joint capsular ligaments? They stabilise the joint and restrict excessive motion. ### What is the primary action of the obliquus capitis superior muscle? Extension and lateral flexion of the head at the atlanto-occipital joint. ## The Vertebral Canal ### Is the anterior wall of the vertebral canal dorsal or ventral? The anterior wall of the vertebral canal is ventral. ### Is the posterior wall of the vertebral canal dorsal or ventral? The posterior wall of the vertebral canal is dorsal. ### Is the dura mater dorsal or ventral? The dura mater surrounds the spinal cord and is neither strictly dorsal nor ventral. ### Is the arachnoid mater dorsal or ventral? The arachnoid mater surrounds the spinal cord and is neither strictly dorsal nor ventral. ### Is the pia mater dorsal or ventral? The pia mater directly adheres to the spinal cord and is neither strictly dorsal nor ventral. ### What does the anterior wall of the vertebral canal consist of? The anterior wall consists of vertebral bodies, intervertebral discs, and the posterior longitudinal ligament. ### What does the posterior wall of the vertebral canal consist of? The posterior wall consists of the laminae, ligamentum flavum, and zygapophyseal joints. ### Describe the dura mater. The dura mater is the tough outer meningeal layer forming a loose sheath around the spinal cord. ### Describe the arachnoid mater. The arachnoid mater is a thin, web-like membrane lining the inside of the dura mater. ### Describe the pia mater. The pia mater is the innermost meningeal layer, adhering to the spinal cord and nerve roots. ### Which nerve supplies the structures in the epidural space? The recurrent meningeal nerves supply structures in the epidural space. ### A lesion to which nerve would affect the dura mater? → Describe the positioning at joints. A lesion to the recurrent meningeal nerve may result in pain localised to the intervertebral joints and surrounding dura. ### Aside from generic trauma, what is a common injury mechanism for the ligamentum flavum in the vertebral canal? Degeneration and thickening of the ligamentum flavum can lead to spinal stenosis. ### Aside from generic trauma, what is a common injury mechanism for the posterior longitudinal ligament? Herniated intervertebral discs can compress and injure the posterior longitudinal ligament. ### Name a common action of the denticulate ligaments. The denticulate ligaments stabilise the spinal cord by anchoring it laterally to the dura mater. ### Name a common action of the filum terminale. The filum terminale anchors the spinal cord to the coccyx, preventing superior displacement. ### Which segment of the vertebral canal contains the cauda equina? The lumbar and sacral segments of the vertebral canal contain the cauda equina. ### Which segment of the vertebral canal contains the conus medullaris? The conus medullaris is found at the L1 vertebral level. ### Which space does the epidural fat occupy in the vertebral canal? Epidural fat occupies the space between the dura mater and the bony walls of the vertebral canal. ### Which space does the subarachnoid space occupy? The subarachnoid space lies between the arachnoid mater and the pia mater; filled with cerebrospinal fluid. ### What are the boundaries/contents of the vertebral canal in the thoracic region? - **Boundaries:** Vertebral bodies, pedicles, laminae, and intervertebral discs. - **Contents:** Spinal cord, meninges, cerebrospinal fluid, and segmental nerves. ### What are the boundaries/contents of the lumbar cistern? - **Boundaries:** Continuation of the subarachnoid space between L1 and S2. - **Contents:** Cauda equina, cerebrospinal fluid, and filum terminale. ### Name a sagittal plane movement of the spinal cord within the vertebral canal. The spinal cord moves ventrally during flexion and dorsally during extension. ### What is the unilateral action of the denticulate ligaments? The denticulate ligaments provide lateral stability to the spinal cord. ### What is the bilateral action of the dura mater? The dura mater provides vertical stability to the spinal cord by anchoring to the foramen magnum and сосcyх. ### What is the most distal point of the spinal cord? The conus medullaris at the L1 vertebral level. ### What is the most distal structure in the vertebral canal? The filum terminale externum, which attaches to the coccyx. ### Which movement can the denticulate ligaments prevent/restrict/control? The denticulate ligaments restrict excessive lateral movement of the spinal cord. ### Which movement can the filum terminale prevent/restrict/control? The filum terminale restricts superior displacement of the spinal cord. ### Which of the meningeal layers continues beyond the spinal cord? The pia mater continues as the filum terminale, and the dura mater continues into the sacral canal. ### Which vertebral element forms the sacral hiatus? The sacral hiatus is formed by the incomplete fusion of the laminae of the fifth sacral vertebra. ### Movements in which cardinal planes are permissible for the spinal cord within the vertebral canal? - **Sagittal:** Ventral and dorsal movement - **Frontal:** Minimal lateral movement restricted by the denticulate ligaments. ### What type of movement occurs during flexion of the lumbar spine on the spinal cord? The spinal cord moves ventrally during lumbar flexion. ### What type of muscle contraction supports the spinal cord during vertebral extension? Isometric contraction of the intrinsic back muscles supports the spinal cord during vertebral extension. ### How many spinal nerve pairs arise from the vertebral canal? Thirty-one pairs of spinal nerves arise from the vertebral canal. ### How many segments does the conus medullaris span in the fetal spine? The conus medullaris spans the entire vertebral column in the early fetal stage. ### Which vertebral region is the epidural space widest? The epidural space is widest in the lumbar region. ### Which vertebral region is the subarachnoid space most accessible? The subarachnoid space is most accessible in the lumbar cistern. ### Which movements are favoured/NOT possible for the spinal cord within the vertebral canal? - **Favoured:** Ventral and dorsal movement. - **NOT possible:** Significant lateral movement due to the denticulate ligaments. ### What is the significance of the sacral hiatus in clinical procedures? The sacral hiatus provides access to the epidural space for caudal epidural anaesthesia. ### What are the attachments of the dura mater in the vertebral canal? The dura mater attaches firmly to the circumference of the foramen magnum, loosely to the posterior longitudinal ligament, and firmly to the dorsal surface of the coccyx. ### What structures are found within the epidural space? The epidural space contains fat, the internal vertebral venous plexus, and segmental arteries. ### Why is the lumbar cistern a preferred site for lumbar puncture? The lumbar cistern provides a large subarachnoid space at L3/4, with no risk of damaging the spinal cord due to its termination at L1. ### How do the denticulate ligaments stabilise the spinal cord? The denticulate ligaments project laterally from the pia mater, anchoring to the dura mater, preventing excessive movement within the vertebral canal. ### What is the clinical implication of a potential subdural space? The subdural space is a pathological space that may form during trauma, leading to subdural haematoma and compression of the spinal cord. ### What is the function of the internal vertebral venous plexus? The internal vertebral venous plexus provides venous drainage from the spinal cord and surrounding tissues. ### What are the segmental changes in the organisation of the spinal cord? The cervical and lumbar enlargements contain more grey matter for limb innervation, while the thoracic and sacral regions show autonomic nerve components. ### Why does the vertebral canal vary in size across regions? The canal is larger in the cervical and lumbar regions to accommodate greater spinal cord volume and mobility, while it is smaller in the thoracic region due to rib attachments. ### What is the significance of the filum terminale? The filum terminale anchors the spinal cord to the coccyx, maintaining longitudinal stability within the vertebral canal. ### What is the role of cerebrospinal fluid in the subarachnoid space? Cerebrospinal fluid cushions the spinal cord, removes metabolic waste, and provides nutrients to the neural tissue. ### What is the difference between the conus medullaris and the cauda equina? The conus medullaris is the tapered end of the spinal cord, while the cauda equina consists of spinal nerve roots extending below the conus. ### What clinical condition may result from compression of the cauda equina? Cauda equina syndrome causes sensory and motor deficits in the lower limbs, bladder dysfunction, and perineal numbness. ### What is the function of the arachnoid trabeculae in the subarachnoid space? The arachnoid trabeculae connect the arachnoid and pia mater, helping to stabilise the spinal cord within the cerebrospinal fluid. ### What are the clinical applications of the epidural space in anaesthesia? The epidural space allows delivery of anaesthetics, providing segmental nerve block for procedures like labour and caesarean sections. ### How does spinal cord movement within the vertebral canal affect back pain? Flexion moves the cord ventrally, and extension moves it dorsally; which can compress nerve roots and lead to flexion/extension-induced back pain. ### What distinguishes the subarachnoid space from the epidural space? The subarachnoid space contains cerebrospinal fluid and is enclosed by the arachnoid and pia mater, while the epidural space lies outside the dura mater and contains fat and veins. ### Why is the conus medullaris located at different vertebral levels during development? The vertebral column grows faster than the spinal cord; shifting the conus medullaris from the coccyx in early fetal life to L1 in adults. ### What structural features protect the spinal cord within the vertebral canal? The vertebral canal walls, meninges (dura, arachnoid, pia mater), cerebrospinal fluid, and denticulate ligaments provide mechanical protection. ### What is the significance of the last denticulate ligament at L1? The last denticulate ligament at L1 marks the end of lateral spinal cord stabilisation, after which the filum terminale provides longitudinal stability. ### What is the relationship between spinal nerve segments and intervertebral foramina in the lumbar region? Lumbar spinal nerves descend 3–5 vertebral segments to reach their respective intervertebral foramina. ### How do the white and grey matter distributions vary