Outline flashcards for the SC

• Protective structures of spinal cord

  • Vertebral Column – SC in vertebral canal, held in place by vertebral ligaments
  • Meninges – CT coverings, all continuous into brain and spinal nerves (different names):

  1. Dura mater ("tough mother"), dense irregular CT, most superficial, strongest

  • Subdural space – contains ISF

  2. Arachnoid mater ("spider-like"), thin avascular covering of collagen and some elastic fibers

  • Subarachnoid space – contains cerebrospinal fluid

  3. Pia mater ("delicate"), innermost, transparent CT of thin squamous to cuboidal cells with interlacing collagen, some fine elastic fibers

  • Highly vascularized
  • Adheres to surface of spinal cord & brain
  • Denticulate ligaments extend into arachnoid and dura mater to extend spinal cord

  
• Spinal Cord


  Vital link between brain and body
• Spinal Cord


  • Begins at foramen magnum
  • 3 Functions: Conducts sensory & motor impulses, Outer cord: Ascending tracts - sensory, Descending tracts - motor, Coordination for locomotion
  • Simple repetitive patterns with no sensory feedback
  • Central Pattern Generators (CPG's) - stimulating specific muscles at certain times
  • Reflexes - rapid involuntary response
• Protective Structures


  • Vertebral column
  • Meninges: Dura mater, Subdural space, Arachnoid mater, Subarachnoid space - CSF, Pia mater
• Dura mater


  • Continuous from spinal cord, Dense irregular connective tissue, Subarachnoid space - CSF
• Arachnoid mater


  • Collagen & some elastin, Subarachnoid space - CSF
• Pia mater


  • Delicate, innermost, Squamous-cuboidal cells, Highly vascularized, Adheres to spinal cord & brain, Denticulate ligaments extend to arachnoid & dura mater
• External Anatomy of the Spinal Cord


  Oval shaped, flattened anterior/posterior, Medulla oblongata to L2, 2 enlargements: Cervical (C4-T1) - upper limbs, Lumbar (T9-T12) - lower limbs, Conus medullaris (L1-L2) - tapering inferiorly, Filum terminale - extension of pia mater fusing with arachnoid & dura mater, Anchors spinal cord to sacrum
• Clinical Connection: Spinal Tap vs. Epidural


  Needle inserted into subarachnoid space to draw CSF, provide antibiotics, chemotherapy, anesthetics (spinal), Epidurals are inserted into the epidural space, includes catheter to modulate pain
• Internal Anatomy of the Spinal Cord


  Anterior median fissure, Posterior median sulcus, Grey matter: Cell bodies of neurons, neuroglia, unmyelinated axons, dendrites, Grey commissure, Central canal - CSF, 3 regions: Anterior/Ventral horn - LMN (motor), Posterior/Dorsal horn - Sensory & interneuron, Lateral horn - autonomic
• White Matter of the Spinal Cord

  • 3 General Columns: Anterior (ventral) - contralateral sensory (light touch & pain), also motor, Posterior (dorsal) - ipsilateral sensory only (proprioception, touch, vibration), Lateral - ipsilateral sensory & motor
• Spinal Nerves


  Parallel bundles of neurons & associated neuroglial cells in layers of connective tissue, 31 pairs, each from a segment: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
• Structure of a Single Nerve

  Nerve fiber = axon + glial cells, Covered by endoneurium, Fasciculus (fascicle) = bundles of fibers, Covered by perineurium, Epineurium = thick outer cover, bundles all fasciculi, continuous with dura mater, thick fibroblasts & collagen, makes up 50% of nerve
• Organization of Spinal Nerves

  Posterior / dorsal rootlets - axons of unipolar sensory axons, Posterior/dorsal root ganglion - unipolar cell bodies, Anterior / ventral rootlets - axons of multipolar motor axons, Spinal nerve trunk = mixed sensory/motor
• Branches of a Typical Spinal Nerve


  Posterior ramus - to deep muscles of back/trunk, Anterior ramus - UE/LE, lateral & anterior trunk, Meningeal branch - loops back through intervertebral foramen to vertebrae, vertebral ligament, vessels & meninges, Rami communicantes - autonomic system (white & grey)
• Cervical Plexus


  C1 - C5, Sensory - skin of posterior scalp to ear & neck, Motor - phrenic n. (C3, C4, C5 keep the diaphragm alive!), infrahyoid & geniohyoid muscles
• Brachial Plexus


  C5-T1, Passes over 1st rib and under clavicle, Roots > trunks > divisions > cords > branches, Major branches: Axillary n. - deltoid, teres minor, Radial n. - UE extensors (posterior), Musculocutaneous n. - anterior arm, Median n. - anterior forearm/hand, Ulnar n. - ulnar anterior forearm/hand
• Describe the structure of a nerve

  Describe 4 components of a spinal nerve trunk
• Major nerve branches from the cervical, brachial, lumbar & sacral plexuses

  • Identify
• Draw a monosynaptic & disynaptic reflex

  Describe their differences
• Plexus


  Braid or network
• Plexuses we will consider


  • Cervical
  • Brachial
  • Lumbar
  • Sacral
• Cervical Plexus


  • C1 - C5
  • Sensory - skin of post scalp to ear & neck
  • Motor - phrenic n. (C3, C4, C5 keep the diaphragm alive!), infrahyoid & geniohyoid muscles
• Brachial Plexus

  • C5-T1
  • Passes over 1st rib and under clavicle
  • Roots > trunks > divisions > cords > branches
  • Major branches - Axillary n., Radial n., Musculocutaneous n., Median n., Ulnar n.
• Remember To Drink Cold Beer!


  • Deep "M"
• Lumbar Plexus


  • L1-L4
  • Femoral n. - flexes muscles of hip, extends knee
  • Obturator n. - adductors of thigh
• Sacral Plexus


  • L4 - S5
  • Sup/Infer gluteal nn.
  • Sciatic n. - largest
  • Tibial n. - calf, deep long flexors of leg, intrinsic foot
  • Common fibular n - fibular ms., anterior leg ms., intrinsic foot
• Dermatomes


  Specific segment of skin supplied by one spinal nerve
• All spinal nn. except C1 innervate segment of skin
• Dermatomes are responsible for referred pain
• Primary functions of the spinal cord

  • Describe 3
• Protective structures & associated spaces

  • Identify
• Ascending = Sensory
• Ascending spinal tracts


  • Posterior column - medial lemniscus
  • Spinocerebellar tract
  • Lateral & anterior spinothalamic tracts
• Descending spinal tracts


  • Direct Pathways: Lateral & anterior corticospinal tract, Corticobulbar tracts
  • Indirect pathways: Rubrospinal tract, Tectospinal tract, Vestibulospinal tract, Lateral & medial reticulospinal tracts
• Reflex


  Fast, involuntary sequence of events in response to a stimulus
• Types of reflexes


  • Innate
  • Acquired
  • Spinal
  • Cranial
  • Somatic
  • Autonomic
• Components of Reflex Arcs


  • Sensory receptor
  • Sensory neuron
  • Integrating center
  • Motor neuron
  • Effector
• Classifications of reflexes


  • Monosynaptic
  • Disynaptic
  • Polysynaptic
• Muscle Spindle Reflex


  Monosynaptic, Excitatory