Spinal Cord And Spinal Nerves

Front 1

Spinal Cord

Back 1

reflex circuits- control some of your most rapid reactions to environmental changes
integration- gray matter of the cord, unmilanated axons
sensory and motor tracts- white matter of the cord, to and from the brain, milanted axons

Front 2

External Cord Anatomy: Conus Medullaris

Back 2

bottom part of fused spinal cord

Front 3

External Cord Anatomy: Two Types of Connective Tissue Coverings that Protect the Cord and Provide Physical Stability

Back 3

vertebral column- bony, provides the backbone
spinal meninges- surround the cord as a continuation of the cranial meninges that encircle the brain

Front 4

Three Membranes of Spinal Meninges

Back 4

Dura mater- outermost layer that encloses the entire cord
Arachnoid mater- middle layer, attaches to the dura and forms the roof of the subarachnoid space (SAS) in which cerebral spinal fluid circulates
Pia mater- transparent, pressed up against the cord and is filled with blood vessels that supply nutrients to it

Front 5

External Cord Anatomy: Space

Back 5

epidural space- runs between the dura mater and the vertebrae (filled with blood vessels, lymphatic vessels, and adipose tissue)

subdural space- lies between the dura and the arachnoid (usually only a potential space)

Front 6

Filum Terminale/ Cauda Equina

Back 6

filum terminale- an extension of the pia mater that extends inferiorly and blends with the arachnoid and dura to anchor the spinal cord to the coccyx

cauda equina- "horses tail," are the roots of the lower spinal nerves that angle down alongside the filum terminale

Front 7

Two Enlargements in the Spinal Cord

Back 7

cervical enlargement- C4-T1, correlates with the sensory input and motor output to the upper extremities

lumbar enlargement- T9-T12, handles motor output and sensory input to and from the legs

Front 8

Roots/ Rootlets

Back 8

roots- connect each spinal nerve to a segment of the cord by even smaller bundles of axons called- rootlets
- white matter

Front 9

Posterior (Dorsal) Root/ Rootlets

Back 9

contain only sensory axons, which conduct nerve impulses from sensory receptors in the skin, muscles and internal organs into the central nervous system

Front 10

Anterior (Ventral) Root/ Rootlets

Back 10

contain axons of motor neurons, which conduct nerve impulses form the CNS to effectors (muscle and glands)

Front 11

Lumbar Puncture

Back 11

a needle inserted into the subarachnoid space for the purpose of withdrawing CSF (for diagnosis or to reduce pressure) or to introduce a drug or contrast agent
- below conus medullaris

Front 12

Internal Cord Anatomy

Back 12

in the spinal cord, white matter is on the outside and gray matter is on the inside. in the brain, the white matter is on the inside and the gray matter is on the outside

Front 13

Internal Cord Anatomy: Horns

Back 13

anterior (ventral) gray horns- consist of somatic motor neurons

posterior (dorsal) gray horns- consist of primarily interneurons, also contains cell bodies of sensory neurons

lateral gray horns- found only in the thoracic, upper lumbar, and sacral segments of the cord
- they contain cell bodies of automatic (involuntary movement) motor neurons

Front 14

Internal Cord Anatomy: Fissure/ Sulcus/ Canal

Back 14

anterior median fissure
posterior median sulcus
central canal- extends the entire length of the spinal cord and is filled with CSF

Front 15

Internal Cord Anatomy: Tract

Back 15

a bundle of neuronal axons that are all located in a specific area of the cord and all traveling to the same place (higher or lower in the brain or cord)

Front 16

Internal Cord Anatomy: Columns

Back 16

anterior, posterior, and lateral columns in which ascending sensory tracts are traveling to someplace in the brain and descending motor tracts are traveling to a location in the cord

Front 17

Internal Cord Anatomy: Spinothalamic Tract

Back 17

an afferent tract that transmits sensations
- e.g., pain, warmth, coolness, itching, tickling, deep pressure, and crude touch

Front 18

Internal Cord Anatomy: Lateral and Anterior Corticospinal Tracts

Back 18

major pathways for carrying signals from the cerebral cortex that result in voluntary movement of skeletal muscles

Front 19

Damage to the Cord: Transection of the Spinal Cord

Back 19

means that ascending and descending tracts are partially or completely severed
- at the base of skull results in death by asphyxiation
- in the upper cervical area results in quadriplegia
- between the cord enlargements results in some form of paraplegia

Front 20

Peripheral Nerves

Back 20

spinal nerves are the paths of communication between the spinal cord and specific regions of the body

Front 21

31 Left-Right Pairs of Spinal Nerves

Back 21

emerge from the cord at regular intervals (called segments)- the first pair leaves between the skull and the first cervical vertebrae
- cervical: 8 pairs, C1-C8
- thoracic: 12 pairs, T1-T12
- Lumbar: 5 pairs, L1-L5
- Sacral: 5 pairs, S1-S5
- Coccygeal: 1 nerve pair

Front 22

Piercing the Dura

Back 22

spinal root divides into
- anterior (ventral) ramus: only ones that form plexus
- posterior (dorsal) ramus

Front 23

Major Nerve Plexuses: Formed from Anterior Rami of Spinal Nerves

Back 23

cervical plexus
brachial plexus
celiac (solar) plexus
lumbar plexus
sacral plexus
coccygeal plexus

Front 24

Cervical Plexus

Back 24

formed by the anterior rami of C1-C5, serves the head, neck, and diaphragm
- phrenic nerves: arise from the cervical plexus to supply the major muscle of respiration

Front 25

Brachial Plexus

Back 25

formed by the anterior rami of C5-C8 and T1
- supply the shoulders and the upper limbs

major nerves: musculocutaneous, axillary, radial, median, ulnar, and long thoracic nerve

Front 26

Lumbar Plexus

Back 26

formed by the anterior rami of L1-L4 to supply the anterolateral abdominal wall, external genitalia, and part of the lower limbs
- the femoral and obturator nerves come from the lumbar plexus

Front 27

Sacral Plexus

Back 27

formed by the anterior rami of L4-L5 and S1-S4.
- supplies the buttocks, perineum, and part of the lower limbs
- gives rise to the largest nerve in the body, sciatic nerve

Front 28

Coccygeal Plexus

Back 28

formed by the anterior rami of S4-S5 and the coccygeal nerves
- small area of skin in the coccygeal region

Front 29

Nerve Terminology

Back 29

rootlets (from cords) - roots (ant and post) - segmental nerves ( spinal nerves) - anterior ramus - form large nerve plexus - posterior ramus (do not form plexus) - rami (form of automatic functions) communicantes

Front 30

Reflexes

Back 30

doesn't need to involve the brain

monosynaptic - sensory neuron with motor neuron
polysynaptic - involving interneurons

they can go in and out on the same or on the opposite side of the cord

Front 31

Reflex Arc

Back 31

pathway that a nerve impulse follows to produce a reflex
- involuntary

Sensory receptor - responds to a stimulus by producing a receptor potential

Sensory neuron - axon conducts impulses from receptor to integration center

Intergrating center - 1 or more regions within the CNS that relay impulses from sensory to motor neurons

Motor neuron - axon conducts impulses from integrating center to effector

Effector - muscle or gland that responds to motor nerve impulses

Front 32

Ipsilateral/ Contralateral

Back 32

- all neurons and effectors on the same side of the body

- the receptors and afferent neurons are on the opposite side of the body as the efferent neurons and effectors

Front 33

Dermatomes

Back 33

an area of the skin that is innervated by a single nerve
- where sensation is linked to nerve