Chapter 16: Spinal Cord And Spinal Nerves

Front 1

Cervical Part

Back 1

the superior most region of the spinal cord

- continuous with the medulla oblogata

- cervical part contains neurons whose axons contribute to cervical spinal nerves and receive input form sensory neuron these spinal nerves

Front 2

Thoracic Part

Back 2

lies inferior to the cervical part

- contains neurons for the thoracic spinal nerves

Front 3

Lumbar Part

Back 3

a shorter segment of the spinal cord that contains the neurons of the lumbar spinal nerves `

Front 4

Sacral Part

Back 4

lies inferior to the lumbar part and contain neurons for the sacral spinal nerves

Front 5

Coccygeal Part

Back 5

the most inferior tip of the spinal cord

- one pair of coccygeal spinal nerves arises form this region

Front 6

Conus Medullaris

Back 6

the tapering inferior end of the spinal cord

- makes the official end of the spinal cord

Front 7

Cauda Equina

Back 7

- groups of axons collectively project interiorly form the spinal cord

Front 8

Filum Ternimale

Back 8

thin strand of pia matter that helps anchor the conus medullaris to the coccyx

Front 9

External longitudinal Depressions

Back 9

- posterior median sulcus

- anterior median sulcus

Front 10

Cervical Enlargement

Back 10

- located in the inferior cervical part of the spinal cord and contains the neurons that innervate the upper limbs

Front 11

Lumbosacral Enlarge

Back 11

- extends through the lumbar and sacral parts of the spinal cord and innervates the lower limb

Front 12

Spinal Cord Meninges

Back 12

- protect and encapsulate the spinal cord

Front 13

Epidural Spaces

Back 13

- spaces that lie between the dura mater and the periosteum covering the inner walls of the vertebrae and houses areloar connective tissue, blood vessels, and adipose connective tissue

Front 14

Spinal Dura Mater

Back 14

- provide stability to the spinal cord

- consist of one meningeal layer

- extends to adjacent vertebrae and fuses with the connective tissue later that surrond the spinal cord

Front 15

Subdural Space

Back 15

- seperades the dura mater form the arachnoid

Front 16

Subarachnoid Space

Back 16

- a real space filled with cerebrospinal fluid

Front 17

Pia Mater

Back 17

deep to the subrarachnoid space

- delicate innermost meningeal layer composed of elastic and collagen fibers

- directly adheres to the spinal cord

Front 18

Denticulate Ligaments

Back 18

- triangular extensions of the spinal pia mater that attach to the dura mater

- help suspend and anchor the spinal cord laterally to the dura mater

Front 19

Gray Matter

Back 19

in the spinal cord is centrally located and its shape resembles a letter H butterfly

- subdivided into four components

Front 20

Anterior Horns

Back 20

- left and right anterior masses of gray matter

- primarly house the cell bodies of somatic motor neurons with innervate the skeletal muscles

Front 21

Lateral Horns

Back 21

- found in the T1 - L2 parts of the spinal cord only

- contain the cell bodies of autonomic motor neurons which innervate the cardiac muscle, smooth muscle, and glands

Front 22

Posterior Horns

Back 22

- the left and right posterior masses of gray matter

- the axons of of sensory neurons and cell bodies of interneurons

Front 23

Gray Commissure

Back 23

- horizontal bar of gray matter that surrounds a narrow central canal

- primarily contains unmyelinated axons and serves as a communication route between the right and left sides of the gray matter

Front 24

Nuclei

Back 24

functional groups of neuron cell bodies

Front 25

Sensory Nuclei

Back 25

the posterior horns contain interneuron cell bodies

Front 26

Somatic Sensory Nuclei

Back 26

receive information from sensory receptors such as pain or pressure reception in the skin

Front 27

Visceral Sensory Nuclei

Back 27

Receive information from sensory receptors such as the stretch receptors in the smooth muscle walls of viscera

Front 28

Motor Nuclei

Back 28

the anterior and lateral horns contain motor neuron cell bodies that send nerve impulses to muscles and glands

Front 29

Somatic Motor Nuclei

Back 29

Anterior horns innervate skeletal muscle while

Front 30

Autonomic Motor Nuclei

Back 30

lateral horns innervate smooth muscle, cardiac muscle, and glands

Front 31

Funiculus

Back 31

White matter partitioned into three regions

Front 32

posterior funiculus

Back 32

lies between the posterior gray horns on the posterior side of the cord and posterior median sulcus

Front 33

Lateral funiculus

Back 33

white matter region on each lateral side of the spinal cord

Front 34

Anterior Funiculus

Back 34

composed of tracts of white matter that occupy the space on each anterior side of the cord between the anterior gray horns and the anterior median fissure

Front 35

White Commissure

Back 35

interconnects the anterior funiculi

Front 36

Anterior Rootless

Back 36

arise from the spinal cord and merge to form a single anterior root

Front 37

Anterior Roots

Back 37

contains only motor axons

- arise from cell bodies in the anterior and lateral horns of the spinal cord

Front 38

Posterior Rootlets

Back 38

- enter the posterior aspect of the spinal cord

- derive from a single posterior root which contains sensory neurons

Front 39

Posterior Roots

Back 39

- contain sensory axons only

- cell bodies of sensory axons are located in the posterior root ganglion

Front 40

Spinal Nerve

Back 40

- have both a motor and sensory axons

- anterior root and its corresponding posterior root

Front 41

Posterior Ramus

Back 41

- Smallest spinal nerve after leaving the intervertebral foramen

- it innervates the deep muscles of the back and the skin of the back

Front 42

Anterior Ramus

Back 42

- larger of the two spinal nerve that leave the intervertebral foramen

- splits into other multiple branches

- innervate the the anterior and lateral portions of the trunk, upper limbs, and the lower limbs

Front 43

Dermatome

Back 43

- specific sengment of skin supplies by a single spinal nerve

Front 44

Referred Visceral Pain

Back 44

- a phenomenon in which pain or discomfort from one organ is mistaking refereed to a dermatome

Front 45

Nerve Plexus

Back 45

network of interweaving anterior rami of spinal nerves

Front 46

Intercostal nerves

Back 46

anterior rami of spinal nerves T1- T11 because they travel in the intercostal space sandwiched between two adjacent ribs

- do not form plexus

Front 47

Cervical Plexus

Back 47

- located deep one each side of the neck immediately lateral to cervical vertebrae C1 - C4

- innervate anterior neck muscles as well as the skin of the neck and portions of head and shoulders

Front 48

Phrenic Nerve

Back 48

- important branch of the cervical plexus

- formed primary from the C4 nerve and some contributing axons from C3 and C5

- travels through the thoracic cavity to innervate the diaphragm

Front 49

Brachial plexus

Back 49

- networks of nerves that supply the upper limb

- formed form the anterior rami of spinal nerves C5 - T1

- innervates the pectoral girdle and the inter upper limb of one side

Front 50

Superior Middle and Inferior Trunks

Back 50

- five roots of the brachial plexus unite to form the posterior triangle of the neck

Front 51

Posterior and Anterior Divisions

Back 51

- portions of each trunk divide infeiror to the clavicle

- primarily contain axons that innervate the anterior and posterior parts of the upper limb

- converge to form three cords near the axillary artery

Front 52

Posterior Cord

Back 52

- posterior to the axillary artery and if formed by the posterior dicison of the superior, middle, and inferior trunks

Front 53

Medial Cord

Back 53

- medial to the axillary artery and if formed by the anterior division of the infeiror trunk

Front 54

Lateral Cord

Back 54

is lateral to the axillary artery and it is formed from the anterior divisions of the superior and middle trunks

Front 55

Terminal branches

Back 55

five major branches that emerge from the 3 cords

Front 56

Axillary nerve

Back 56

Travels: through the axilla and posterior to the surgical neck of the humerus

Emerges: from posterior cord of the brachial plexus

Innervates: deltoid and teres minor

Front 57

Musculocutaneous Nerve

Back 57

Arises: from the lateral cord the brachial plexus

Innervates: anterior arms muscles and receives sensory information form the lateral surface of the forearm

Front 58

Radial Nerve

Back 58

Arises: from the posterior cord of the brachial plexus

Travels: along the posterior side of the arm and then along the radial side of the forearm

Innervates: the posterior arm muscles and posterior forearm muscles and receives sensory information from the posterior arm

Front 59

Ulnar Nerve

Back 59

Arises: the medial cord of the brachial plexus and descends along the medial side of the arm

Innervates: some the anterior arm muscles and most of the intrinsic hand muscles

Front 60

Lumbar Plexus

Back 60

- formed from the anterior rami of spinal nerves L1 - L4

- subdivided into anterior and posterior division

Front 61

Femoral Nerve

Back 61

- main nerve of the lumbar plexus

- supplies the anterior thigh muscles and also receives sensory information form the anterior and intermedial thigh as well as the medial aspect of the led

Front 62

Obturator Nerve

Back 62

- travels: through the obturator foramen to the medial thigh and receives sensory information form the supermedial skin of the thigh

Front 63

Sacral Plexuses

Back 63

- formed form the anterior rami of spinal nerves L4 and S4

Innervate: the gulteal region, pelvis, perineum, posterior thigh, and almost all the leg and foot

Front 64

Sciatic Nerve

Back 64

- largest and longest nerve in the body

- Projects: form the pelvis through the greater sciatic notch of the os coxae and extends to the posterior region of the thigh

- separates into two nerves

Front 65

Tibial Nerve

(Sciatic Nerve)

Back 65

- formed from the anterior divison of the sicativ nerve

- innervates the hamstrings and part of the adductor magnus

Front 66

Common Fibular Nerve

(Sciatic Nerve)

Back 66

- formed from the posterior divisions of the sciatic nerve

- supplies the short head of the biceps femoris muscle

- wraps around the head of the fibula

- splits into two main branches

Front 67

Deep Fibular Nerve

(Common Fibular Nerve)

Back 67

- travels: in the anterior compartment of the leg and terminates between the first and second toe

- supplies: anterior leg muscle and the muscles on the dorsum of the foot

- receives: sensory innervation from skin between the first and second toes

Front 68

Superficial Fibular Nerve

Back 68

- travels: in the lateral compartment of the leg

- innervates: the lateral compartment muscles of the leg

Conducts: sensory impulses from most of the dorsal surface of the foots and anterinferior part of the leg

Front 69

Reflexes

Back 69

rapid, automatic, involuntary reacitons of msulces or glands to a stimulus

Front 70

Properties of Reflexes

Back 70

- a stimulus is required

- rapid response requires a few neurons to be involved

- automatic response

- involuntary response

Front 71

Reflex Arc

Back 71

the neural wiring of a single reflex

Front 72

Fives Steps of a Reflex Arc

Back 72

1) stimulus activates receptors

2) nerve impulses travels through sensory neuron to the CNS

3) information form the nerve impulses is processes n the integration center by interneurons

4) motor neuron transmit nerve impulses to effector

5) Effector responds to nerve impulse from motor neurons

Front 73

isilateral reflex arc

Back 73

when both the receptor and effector organs of the reflex are on the same side of the spinal cord

Front 74

Contraleral reflex arc

Back 74

when the sensory impulses form the receptor organ cross over the spinal cord to activate organs in the opposite limb

Front 75

Monosynaptic Reflex

Back 75

the simplies of all reflexes

- no interneurons are involved

- very prompt reflex response

Front 76

Polysynaptic Reflexes

Back 76

more complex neural pathways that exhibit a number of synapses involving interneurons with the reflex arc

Front 77

Withdrawal Reflex

Back 77

polysnaptic reflex arc that is intiated by a pianful stimulus

- stimulation of receptor organ cuases transmission of sensroy informaiton to the spinal cord

Front 78

Stretch Reflex

Back 78

- monosynaptic reflex that monitors and regulates skeletal muscle length

- stretch is monitored by muscle spindle

Front 79

Golgi Tendon Reflex

Back 79

- a polysynaptic reflex that prevents skeletal muscle form tensing excessively

- Golgi tendon organs are nerve endings located within the tendon to prevent excessive tension damage

Front 80

Hypoactive reflex

Back 80

reflex response is diminished or absent

- indicates damage to a dement of the spinal cord or muscle disease

Front 81

Hyperactive reflex

Back 81

abnormal strong reflex

- indicated damge somewhere in the brain or spinal cord

Front 82

Clonus

Back 82

rhythmic oscillations between flexion and extension when the muscle reflex is tested