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SPINAL CORD ANATOMY & PHYSIOLOGY HONORS ANATOMY & PHYSIOLOGY.

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Presentation on theme: "SPINAL CORD ANATOMY & PHYSIOLOGY HONORS ANATOMY & PHYSIOLOGY."— Presentation transcript:

1 SPINAL CORD ANATOMY & PHYSIOLOGY HONORS ANATOMY & PHYSIOLOGY

2 Spinal Cord  w/spinal nerves contain neural circuits that mediate some of your most rapid reactions to environmental changes

3 Protective Structures  2 types of CT coverings surround & protect delicate nervous tissue 1. bony vertebrae 2. tough CT meninges, w/cushion of CSF

4 Meninges  3 CT coverings that encircle spinal cord & brain:  Spinal meninges covers spinal cord  Cranial meninges covers brain

5 Meninges Layers: Dura Mater  “tough mother”  most superficial layer  made of dense, irregular CT  continuous with cranial meninges  forms sac from foramen magnum  S2  layer of adipose tissue between dura mater & wall of vertebral cavity (epidural space)

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7 Middle Meninges: Arachnoid Mater  “spider-like”  deep to dura mater, superficial to pia mater  contiguous with cranial arachnoid  between dura & arachnoid = subdural space

8 Innermost Meninges:Pia mater  “delicate”  thin, transparent CT  adheres to spinal cord & brain  between arachnoid & pia = subarachnoid space

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10 Spinal Tap  aka lumbar puncture  long needle inserted into subarachnoid space  adults: between L3 –L4 or L4 – L5 (inferior to lowest portion of spinal cord)  purpose: withdraw CSF for  diagnostic purposes  insert antibiotics/contrast media for myelography/ anesthetics/ chemotherapy

11 Spinal Cord  cylindrical with flattening of its AP diameter  adults:extends from medulla oblongata  L2 vertebra  newborns: extends to L3 or L4  elongation of spinal cord stops ~age 3-4 but growth of vertebral column continues

12 Spinal Cord: External View  2 obvious enlargements noted:  cervical enlargement C4 – T1 serve upper limbs  lumbar enlargement T9- T12 serve lower limbs

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14 Spinal Cord: External View  conus medullaris: tapered conical structure of spinal cord below lumbar enlargement ending @ L1 – L2  filum terminale: extension of pia mater extends inferiorly & anchors cord to coccyx  cauda equinae: “horse tail” nerves that arise from lumbar, sacral, & coccygeal portions of spine

15 Conus Medullaris

16 Filum Terminale

17 Cauda Equina

18 Spinal Nerves  31 pairs spinal nerves emerge thru intervertebral foramen  8 pair cervical nerves: C1 – C8  12 pair thoracic nerves: T1 - T12  5 pair lumbar nerves: L1 – L5  5 pair sacral nerves: S1 – S5  1 pair coccygeal nerves: Co1

19 Spinal Nerves  2 bundles of axons, called roots, connect each spinal nerve to segment of spinal cord

20 Spinal Cord Roots 1. posterior (dorsal) root  only sensory axons  each has dorsal root ganglion containing cell bodies of sensory neurons 2. anterior (ventral) root  only motor axons

21 Internal Anatomy of Spinal Cord  2 grooves penetrate white matter & divide it in right & left sides: 1. anterior median fissure 1. deeper, wider of the 2 2. posterior median sulcus 1. shallower, narrow furrow

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23 Internal Anatomy of Spinal Cord  gray matter shaped like “H” or a butterfly & is surrounded by white matter  gray commissure forms the “H” crossbar  central canal small hole in its center extends entire length of spinal cord filled with CSF @ superior end is contiguous with 4 th ventricle of brain

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25 Spinal Nerves  & the nerves that branch off them are part of PNS  emerge from vertebral column thru intervertebral foramina

26 Spinal Nerves  typically has 2 connections to spinal cord 1. dorsal root (sensory) 2. ventral root (motor)  classified as “mixed”

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28 Distribution of Spinal Nerves

29 Spinal Nerve Plexuses  a network of nerves (or veins, or lymphatic vessels)

30 Cervical Plexus  supplies skin & muscles of the head, neck, & superior portion of shoulders, chest, & diaphragm  C1 – C 5

31 Brachial Plexus  supplies the shoulders & upper limbs

32 Lumbar Plexus  supplies anterolateral abd wall, external genitals, part of lower limb

33 Sacral Plexus  supplies buttocks, perineum, & lower limbs

34 Dermatomes  cutaneous area developed from one embryonic spinal cord segment & receiving most of its sensory innervation from one spinal nerve  knowing which spinal cord segments supply each dermatome makes it possible to locate damaged regions of the spinal cord

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36 Reflexes & Reflex Arches  reflex: a fast, automatic, unplanned sequence of actions that occurs in response to a particular stimulus  can be: 1. inborn  pulling hand away from hot stove 2. learned or acquired  foot on brake when see dog run in front of car

37 5 Parts of a Reflex Arc

38 Stretch Reflex

39 Pupillary Light Reflex  pupils of both eyes decrease in diameter when either eye is exposed to light  absence of a normal pupillary light refex indicates possibility of brain damage or injury

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41 Spinal Cord Injuries  most due to trauma  cervical, lower thoracic, upper lumbar most common regions involved  paralysis  depends on location, extent of damage  monoplegia: 1 limb  paraplegia: both lower limbs  hemiplegia: upper limb, trunk, lower limb on 1 side of body  quadriplegia: all 4 limbs & trunk

42 Extent Muscle Paralysis  C1 – C3: no function neck down, requires ventilator to breathe  C4 – C5: diaphragm, allows breathing  C6 – C7: some arm, chest, allows breathing, moving wheelchair  T1 – T3: intact arm function  T4 – T9: control of trunk above umbilicus  T10 – L1: most thigh muscles, walk w/long leg braces  L1 – L2: most leg muscles, walk w/short leg braces

43 Shingles  acute infection of PNS  caused by herpes zoster (chicken pox)  virus stays in posterior root ganglion  becomes reactivated normally immune system will prevent it from spreading  reactivated virus can overcome weakened immune system  leaves ganglion  travels down sensory neurons supplying skin

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45 Medical Terminology  meningitis: inflammation of meminges due to infection, bacterial (worse) or viral, vaccine protests against some bacterial causes: headache, N/V, fever, stiff neck  neuralgia: pain along a sensory nerve, trigeminal neuralgia  neuritis: inflammation of 1 or several nerves  paresthesis: abnormal sensation

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