Week 1 SAQs - Lecture Notes PDF

## Lecture 1 **Is the vertebral centrum dorsal or ventral?** The vertebral centrum is ventral, as it forms the anterior body of the vertebra and lies in front of the neural arch. **Is the notochord pre-axial or post-axial?** The notochord is pre-axial, serving as the central scaffold for the dev...

## Lecture 1 **Is the vertebral centrum dorsal or ventral?** The vertebral centrum is ventral, as it forms the anterior body of the vertebra and lies in front of the neural arch. **Is the notochord pre-axial or post-axial?** The notochord is pre-axial, serving as the central scaffold for the development of the vertebral column. **Name the ossification centers involved in vertebral development.** - **Centrum**: Forms the central portion of the vertebral body. - **Neural arch elements**: Form the dorsal aspect of the vertebral column, surrounding the spinal cord. - **Costal elements**: Develop into ribs in the thoracic region or transverse processes in other regions. **Which nerve supplies intervertebral muscles?** The mixed spinal nerve supplies intervertebral muscles, exiting the vertebral canal through intervertebral foramina at the level of the intervertebral discs. **A lesion to which spinal nerve would produce scoliosis due to hemivertebrae? Describe the clinical presentation.** Lesions of a segmental spinal nerve near a hemivertebra may cause scoliosis, presenting with an asymmetric curvature of the vertebral column. **Aside from generic trauma, what is a common injury mechanism leading to nerve root compression at intervertebral foramina?** A common mechanism is failure of vertebral segmentation, such as in block vertebrae, leading to reduced foraminal space and nerve root compression. **Name a common action of the erector spinae and interspinales muscles.** Both the erector spinae and interspinales muscles contribute to extension of the vertebral column. **Which segment of the vertebral column contributes to thoracic rib development?** The thoracic vertebrae, derived from somites at corresponding levels, contribute to rib formation through their costal elements. ## Lecture 2 **Is the cervical vertebra dorsal or ventral?** The cervical vertebra, like all vertebrae, has both dorsal and ventral components, but 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.** The lumbar vertebrae have large kidney-shaped vertebral bodies, short spinous processes, and 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?** The trapezius, rhomboid major, and latissimus dorsi muscles attach to the thoracic spinous processes. **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 characterised 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.** The cervical vertebra has a small, oval body, transverse foramina, and bifid spinous processes. **Describe the thoracic vertebra.** The thoracic vertebra has a heart-shaped body, costal facets for rib attachment, and long, downward-sloping spinous processes. **Describe the lumbar vertebra.** The lumbar vertebra has a large, kidney-shaped body, short spinous processes, and 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?** The levator costarum, longissimus, and intertransversarii attach at the transverse processes. **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 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?** The anterior longitudinal ligament prevents hyperextension, the posterior longitudinal ligament prevents hyper-flexion, and the 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?** The rectus capitis posterior major performs extension and ipsilateral rotation of the head, while the minor only 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, while extrinsic muscles are limb-associated and innervated by ventral rami. **Which extrinsic muscles attach to the thoracolumbar fascia?** The serratus posterior superior and serratus posterior inferior attach to the thoracolumbar fascia. **What movement does the erector spinae perform during lateral flexion?** The erector spinae performs ipsilateral lateral flexion of the vertebral column. **How does the ligamentum nuchae differ from the supraspinous ligament?** The ligamentum nuchae is an extension of the supraspinous ligament in the cervical region and provides attachment for muscles like the trapezius. **What is the function of the obliquus capitis inferior muscle?** The obliquus capitis inferior performs ipsilateral rotation of the head at the atlanto-axial joint. **What is the importance of the interspinous ligament in vertebral stability?** The interspinous ligament connects adjacent spinous processes, limiting excessive flexion. **How do the thoracic and lumbar regions differ in ligament strength?** Thoracic ligaments are thinner and more flexible to allow breathing, while lumbar ligaments are thicker and stronger to resist high loads. **What is the clinical significance of the greater occipital nerve (C2)?** The greater occipital nerve is often associated with neuralgia and headaches due to its proximity to the suboccipital region. **Which muscle group contributes most to postural stability during prolonged standing?** The erector spinae group maintains postural stability through tonic contraction. **How do the radiate ligaments contribute to rib and vertebral stability?** Radiate ligaments stabilise the costovertebral joints by anchoring the rib heads to the vertebral bodies. **What are the multi-segmental ligaments of the vertebral column?** Anterior longitudinal ligament, posterior longitudinal ligament, and supraspinous ligament. **What is the role of the ligamentum flavum in vertebral function?** It prevents buckling and compression of the spinal cord due to its elastic nature. **Which unisegmental ligaments are found in the vertebral column?** Annulus fibrosus, interspinous ligament, intertransverse ligament, ligamentum flavum, and zygapophyseal joint capsular ligaments. **What innervates intrinsic back muscles?** The dorsal rami of mixed spinal nerves. **What are the three subgroups of the transversospinales muscles?** Rotatores, multifidus, and semispinalis. **Which muscles make up the erector spinae group, and what are their attachments?** - **Spinalis**: (spinous processes) - **Longissimus**: (neural components of transverse processes) - **Iliocostalis**: (costal elements and rib angles). **What is the unilateral action of the erector spinae muscles?** Lateral flexion of the vertebral column. **What structures form the suboccipital triangle?** - **Borders**: Rectus capitis posterior major, obliquus capitis superior, and obliquus capitis inferior. - **Contents**: Vertebral artery and dorsal ramus of C1. **What is the primary action of the rectus capitis posterior muscles?** Extension of the atlanto-occipital joint. **What is the significance of the thoracolumbar fascia in the lumbar region?** It provides strength and reinforcement, particularly through its posterior layer, supported by the latissimus dorsi and gluteus maximus. **What are the layers of the thoracolumbar fascia?** Anterior, middle, and posterior layers, which join laterally to form the abdominal wall muscles. **Which extrinsic muscles are associated with the thoracolumbar fascia?** Serratus posterior superior and 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. ## Lecture 3 **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 coccyx. **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 lumber 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 organization 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 along the spinal cord?** White matter increases towards the brain, while grey matter enlargements occur in the cervical and lumbar regions for limb innervation. **What are the autonomic components of the spinal cord?** The intermediolateral horn contains sympathetic nerves in T1-L2 and parasympathetic nerves in S2-S4. **What structural adaptations support the cauda equina within the lumbar cistern?** The cauda equina is surrounded by cerebrospinal fluid, which cushions and protects the nerve roots. **What are the boundaries and contents of the sacral canal?** - **Boundaries**: Sacral vertebrae, laminae, and sacral hiatus. - **Contents**: Filum terminale externum, sacral nerve roots, fat, and veins. **What structures form the lateral wall of the vertebral canal?** The lateral wall is formed by the pedicles and the intervertebral foramina. **How does the size of the vertebral canal vary by region, and why?** The vertebral canal is larger in the cervical and lumbar regions to accommodate greater movement and larger spinal cord diameters, smaller in the thoracic region due to rib attachments, and reduced in the sacral region as the spinal cord ends. **What is the function of the epidural fat in the vertebral canal?** The epidural fat cushions the spinal cord and provides space for the internal vertebral venous plexus. **What is the significance of the posterior longitudinal ligament in the vertebral canal?** The posterior longitudinal ligament supports the posterior vertebral bodies and restricts hyperflexion. **What is the role of the internal vertebral venous plexus in the epidural space?** The internal vertebral venous plexus drains venous blood from the vertebral column and spinal cord. **How do the attachments of the dura mater differ along the vertebral canal?** The dura mater attaches firmly to the foramen magnum, loosely to the posterior longitudinal ligament, firmly to the dorsal surface of the coccyx, and forms dural sleeves around spinal nerves. **What is the clinical relevance of the lumbar cistern?** The lumbar cistern contains the cauda equina and cerebrospinal fluid, making it an ideal site for lumbar puncture and spinal anaesthesia. **How does the dura mater contribute to anchoring the spinal cord?** The dura mater forms sleeves around spinal nerves, anchoring them to intervertebral foramina and stabilising the cord. **What is the purpose of denticulate ligaments?** Denticulate ligaments are lateral projections of pia mater that anchor the spinal cord to the dura mater, preventing excessive movement. **Why is the cauda equina located in the lumbar cistern?** The cauda equina consists of nerve roots descending from the conus medullaris to their respective intervertebral foramina, located within the lumbar cistern for flexibility and movement. **What is the difference between the subdural and subarachnoid spaces?** The subdural space is a potential space present only in pathology, while the subarachnoid space is a true space filled with cerebrospinal fluid. **What is the significance of the filum terminale internum and externum?** The filum terminale internum is a continuation of pia mater anchoring the conus medullaris to the sacrum, while the filum terminale externum anchors the dural sac to the coccyx. **How do spinal nerves exit the vertebral canal?** Spinal nerves exit the vertebral canal through intervertebral foramina, formed by adjacent vertebrae and the intervertebral discs. **What is the clinical significance of the epidural space in anaesthesia?** The epidural space is used for administering anaesthesia during childbirth or surgery, as it allows for regional nerve blockade without puncturing the dura mater. **How do dorsal and ventral nerve roots contribute to spinal segmentation?** Dorsal and ventral rootlets group into segmental spinal nerves, exiting through specific intervertebral foramina. **What changes occur to the spinal cord position during vertebral flexion and extension?** During flexion, the spinal cord moves ventrally and cranially, while during extension, it moves dorsally and caudally. **How does the organisation of white and grey matter differ within the spinal cord?** White matter (myelinated tracts) increases toward the brain, while grey matter (cell bodies) is prominent at cervical and lumbar enlargements due to limb innervation. **What is the role of the intermediolateral horn in the spinal cord?** The intermediolateral horn contains autonomic neurons, responsible for sympathetic output in thoracic segments (T1-L2) and parasympathetic output in sacral segments (S2-S4). **How does the spinal cord length compare at different stages of development?** The spinal cord extends to the full length of the vertebral column in the fetus, to S1 at birth, and to L1 in adults due to differential growth rates. **Why is the sacral hiatus clinically significant?** The sacral hiatus is an entry point for caudal epidural anaesthesia, targeting sacral nerve roots without puncturing the dural sac. **What is the anatomical relationship between the dorsal root ganglion and the meninges?** The dorsal root ganglion lies within the epidural space, where the meninges transition to peripheral nerve connective tissue. **How do the layers of connective tissue around peripheral nerves relate to the meninges?** The epineurium, perineurium, and endoneurium of peripheral nerves are continuous with the dura mater, arachnoid, and pia mater, respectively. **What is the difference between the cervical and lumbar enlargements of the spinal cord?** The cervical enlargement (C5-T1) innervates the upper limbs via the brachial plexus, while the lumbar enlargement (L1-S3) innervates the lower limbs via the lumbosacral plexus. **Why are lumbar punctures performed at the L3/L4 level?** Lumbar punctures are performed below the conus medullaris to avoid spinal cord injury, utilising the larger subarachnoid space in the lumbar cistern. **How does the structure of the vertebral canal in the sacral region accommodate the filum terminale?** The sacral canal contains the filum terminale externum, sacral nerve roots, and epidural fat, narrowing toward the sacral hiatus. **What is the functional importance of the conus medullaris?** The conus medullaris is the tapered end of the spinal cord, from which nerve roots of the cauda equina arise to supply lower limb and pelvic structures. **How do the meningeal layers terminate at the coccyx?** The pia mater continues as the filum terminale, the dura mater anchors to the coccyx, and the arachnoid ends at the level of the dural sac termination. **What is the clinical significance of the subarachnoid space during spinal block anaesthesia?** The subarachnoid space is the target for spinal block anaesthesia, delivering a single-dose anaesthetic into cerebrospinal fluid for lower body procedures. **What changes occur to the spinal cord diameter along its length?** The spinal cord diameter decreases caudally, with enlargements in the cervical and lumber regions for limb innervation. **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 central nervous system. ## Lecture 5. Pre-Lab 1 **Is the brachial plexus dorsal or ventral?** The brachial plexus is ventral, located in the anterior region of the neck and axilla. **Is the lumbosacral plexus dorsal or ventral?** The lumbosacral plexus is ventral