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What structures protect the spinal cord?. Bones (vertebral column)Meninges, in layers Epidural spaceDura mater Subdural spaceArachnoid mater Subarachnoid space (contains CSF)Pia mater -- very vascular . The meninges.
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1. Lucky Chapter 13.Spinal Cord and Spinal Nerves Biology 315. Anatomy and Physiology I.
2. What structures protect the spinal cord? Bones (vertebral column)
Meninges, in layers
Epidural space
Dura mater
Subdural space
Arachnoid mater
Subarachnoid space (contains CSF)
Pia mater -- very vascular
3. The meninges
4. Another view of the meninges
6. Cervical enlargement C4-T1
7. Segmentation of the Spinal Cord C1-C8
T1-T12
L1-L5
S1-S5
Note differential growth of vertebral column such that adult spinal cord ends at L1-L2 interspace.
8. Spinal Cord Schematic
10. Spinal cord: horns and columns
12. Quiz�
13. Spinal cord tracts�. Ascending tracts = sensory
Spino-thalamic
Descending tracts = motor
*Cortico-spinal
14. Sensory tracts�examples Anterior and lateral spinothalamic tracts
Pain
Temperature
Itching
Tickling
Deep pressure
Crude touch
15. Anterior and lateral spinothalamic tracts
16. Sensory tracts: example Posterior column system
Proprioception
Discriminative touch
2-point discrimination
Light pressure
Vibration
17. Motor tracts: Descending� Direct pathways: �Pyramidal�
Lateral corticospinal tract
Anterior corticospinal tract
Corticobulbar tract
These carry motor impulses that originate from the cerebral cortex and result in
precise, voluntary movements of skeletal muscle.
18. Motor tracts: descending Indirect pathways (Extrapyramidal)
Rubrospinal
Tectospinal
Vestibulospinal
These carry impulses from brain stem,
coordinate movements with visual stimuli
Regulate muscle tone
Maintain contraction of postural muscles
Equilibrium
19. Motor tracts���.
20. What is a reflex? A fast, involuntary, unplanned sequence of actions that occurs in response to a particular stimulus.
Somatic: contraction of skeletal muscles
Autonomic (visceral):urination, gastrocolic�
(easy one to test: pupillary light reflex)
Consider Newtons 3rd law: For every action there is an equal and opposite reaction.
21. What makes up a reflex?: 5 components Sensory receptor
Sensory neuron
Integrating center (multisynaptic or monosynaptic; spinal cord or brain stem)
Motor neuron
Effector (skeletal muscle, smooth muscle, cardiac muscle, glands)
22. The Stretch Reflex: monosynaptic, ipsilateral Receptor: muscle spindle,monitors stretch
Sensory nerve: from receptor through posterior root
Integrating center: spinal cord; sensory neuron synapses with
Motor neuron in the anterior gray horn
Motor axon travels out anterior root to PNS to muscle
23. Reciprocal innervation: If the agonist muscle contracts, the
Antagonist muscle must _____________
If not, the two muscle groups are in conflict and the appropriate movement can�t occur.
24. The Tendon Reflex: also protective Receptor: Golgi tendon organ detects increased muscle tension
Nerve impulse carried through posterior root into posterior horn
Integrating center: spinal cord, inhibitory neuron synapses with a motor neuron , which is hyperpolarized (inhibited)
Effector muscle of that tendon relaxes and relieves excess tension.
26. Flexor-Crossed Extensor Reflex I. Receptor: pain receptors
Sensory neuron to spinal cord
Integrating center: spinal cord, various segments (intersegmental) ,multiple neurons
Motor neurons send impulses to
Neuromuscular junctions�
ACh : flexors contract; others inhibited. You pull your foot back�..
27. Flexor-Crossed Extensor Reflex II. In spinal cord interneurons synapse with motor neurons on the opposite side of the spinal cord ( contralateral)
Motor neurons carry nerve impulse to nerve ending,
Effector: contraction of extensor muscles of the opposite side
28. Why do reflex testing? If a given reflex �works,� all the parts of that reflex must be intact. (receptor; sensory neuron; integrative center; motor neuron; effector).
Various reflexes test specific spinal cord levels
E.g. patellar reflex: L2-L4
Achilles: lumbosacral levels
29. The True Blue Spinal Nerves Terms to review
Anterior root
Posterior root
Spinal nerve
Ramus
Plexus
30. Structure of a peripheral nerve
31. Structure of a peripheral nerve
32. The generic, but True Blue, spinal nerve
33. The generic, but True Blue, spinal nerve
34. The generic, but True Blue, spinal nerve
35. Distribution of Spinal Nerves Dorsal ramus: supplies muscles and skin of back
Ventral ramus: extremities, lateral and ventral trunk (the big one)
Ventral rami of T2-T12 = intercostal nerves
Ramus (pl. rami) communicantes: part of ANS
36. What is a plexus ? Ventral rami of spinal nerves branch and form networks
Cervical plexus = C1-C4
Innervates skin, muscles of neck, head,shoulder region plus diaphragm.
Connects with XI (spinal accessory) and XII
(Hypoglossal)
THE NERVE to know = Phrenic: C3,C4,C5
37. What is a plexus ? Ventral rami of spinal nerves branch and form networks
Brachial = C5-T1
Upper extremity
Some neck/ shoulder areas
Complicated structure (trunks/ divisions/cords)
THE NERVES to know
38. The Brachial Plexus �� 6 nerves to know
Axillary nerve: deltoid, teres major
Musculocutaneous nerve: flexors of arm and forearm
Radial nerve: muscles of posterior arm and forearm
Damage to radial nerve: �wrist drop�
39. The Brachial Plexus ��Part Deux Median Nerve: muscles of anterior forearm and palm thumb
Damage = numbness, tingling pain in fingers, weak thumb movements, inability to pronate forearm
Ulnar nerve : anteromedial muscles of forearm and fingers
Damage: difficulty holding/picking up piece of paper; inability to flex and adduct the wrist
Long thoracic nerve: serratus anterior
Damage: �winged� scapula
40. The Lumbar Plexus: L1-L4 Femoral nerve: flexors of the thigh and extensors of the legs (quads; iliopsoas; sartorius);skin over anterior and medial aspect of thigh and medial side of leg and foot
Know that these nerves are part of the lumbar plexus:
Iliohypogastric
Ilioinguinal
Genitofemoral
Lateral cutaneous nerve of the thigh
Obturator nerve
41. The Sacral Plexus: L4-S4 Buttocks, perineum, lower extremity
Sciatic nerve : largest nerve; composed of tibial and common fibular/peroneal nerve
Tibial nerve: posterior compartment muscles; medial and lateral plantar nerves
Common Fibular/Peroneal nerve : anterior compartment, lateral compartment of leg
Pudendal nerve = muscles of perineum, skin over external genitalia, vagina
Damage: �foot drop�
42. Dermatome: skin supplied by the dorsal root of a spinal nerve
43. Dermatome: skin supplied by the dorsal root of a spinal nerve
45. Notes on dermatomes: related to development Helpful for determining general level of injury or anesthesia
Herpes zoster follows the dermatomes
Same organization for MYOTOMES
Try to memorize a few�.
Shoulder C3-C4
Nipple T4
Umbilicus T10
46. Transection of the spinal cord 1. Permanent loss of sensation in dermatomes distal to the injury
2. Permanent loss of voluntary muscle contraction distal to the injury
47. A few last terms�. Polio
Meningitis
Nerve block
Epidural block
Neuralgia
Neuritis
Paresthesia
Shingles