Anatomy - Ch 17 (Spinal cord)

polysynaptic reflex

A reflex invovling one or several interneurons.

Epineurium

Dense connective tissue that surrounds entire nerve including fascicles and blood vessels.

rootlets

Spinal nerves initially arise from the spinal cord as

gray and white commissures

axons that cross from one side of the spinal cord to the other

fascicle or fasciculi

bundle of muscle fibers

sensory nerve

dorsal root (enters)

Median nerve injury

opponens splint, C-bar or thumb post splint

Which of these is NOT a region of the spinal cord?

pelvic

spinal reflexes

simple pathways in the nervous system that rapidly generate muscle contractions

posterior (dorsal) gray horn has 2 parts:

somatic (skeletal muscle) portion visceral (organs) portion

anterior (ventral) white column

somatic motor tracts, anterior (ventral) surface of spinal cord

conus medullaris

tapered end of spinal cord

motor nerve

ventral root (exits)

autonomic reflexes

(visceral) regulate the activity of smooth muscles, the heart, and glands

dorsal root ganglion

- cell bodies of sensory neurons - glial cells here are satellite cells

mixed spinal nerve

- nerve that is formed of dorsal and ventral roots - sensory (afferent) = brings sensory to the CNS -motor (efferent) = brings commands way from CNS to visceral (organs)

length of adult spinal cord

42-45 cm (16-18 in)

reflex arc

A relatively direct connection between a sensory neuron and a motor neuron that allows an extremely rapid response to a stimulus, often without conscious brain involvement.

denticulate ligaments

Specializations of the pia mater that anchor the spinal cord to the dura mater and limit the movement of the cord.

filum terminale

anchors spinal cord to coccyx

In the spinal cord, the somas (cell bodies) of the lower motor neurons are found in the:

anterior horns

Dermatomes

are skin segments that relate to sensory innervation regions of the spinal nerves

The nerve branching off of C5 can belong to both the _________ and ________ plexuses.

cervical; brachial

Ulnar nerve injury

claw hand

Perineurium

connective tissue that bundles fibers into fascicles

motor (descending) tracts

consist of axons that carry nerve impulses from the brain and away

sensory (ascending) tracts

consist of axons that conduct nerve impulses toward the brain

arachmoid mater

contains CSF in the middle

Endoneurium

delicate connective tissue around each axon

The following helps prevent lateral and inferior movement of the spinal cord:

denticulate ligaments

The ____________ is the outermost meninx, and forms supportive and protective partitions between some portions of the brain.

dura mater

Meninges

dura mater, arachnoid mater, pia mater

Lumbar Plexus (L1-L4)

femoral nerve

Further you go down the spinal cord what gets larger?

gray matter

superior trunk

roots: C5 & C6 cords: posterior & lateral nerves: musculocutaneous & median

middle trunk

roots: C7 cords: posterior & lateral nerves: axillary & radial

inferior trunk

roots: C8 & T1 cords: posterior & medial nerves: ulnar & median

posterior (dorsal) ramus

serves the deep muscles and skin of the posterior surface of the trunk

long thoracic nerve injury

winged scapula

Radial nerve injury

wrist drop

components of a reflex arc

1. sensory receptor 2. sensory neuron 3. integration center 4. motor neuron 5. effector

pia mater

Innermost layer of the meninges (delicate mother)

monosynaptic reflex

Reflex pathway with only one synapse between the sensory and motor neurons (ex: knee-jerk).

Cutaneous Fields

Regions of skin supplied by a specific nerve arising from a plexus

Sacral Plexus (L4-S4)

Superior gluteal nerve Inferior gluteal nerve Sciatic nerve • Tibial nerve • Common fibular (peroneal) nerve

Erb-Duchenne palsy

Superior trunk brachial plexus injury ("waiter's tip")

somatic reflexes

activation of skeletal muscles

Which cord is formed by all trunks?

posterior

all trunks form what?

posterior cord

cervical plexus

C1-C5

The superior trunk originates from the branches of which cervical nerve?

C5 and C6

brachial plexus

C5-C8, T1

The middle trunk arises from which cervical nerve(s)?

C7

phrenic nerve

innervates the diaphragm C3-C5

plexus

large, interlacing network of nerves

lateral white column

lateral part of white matter function: tissue through which messages pass between different areas of gray matter

lateral gray horn

located only in thoracic and lumbar segments, contains visceral motor nuclei -visceral portion

lumbar enlargement

nerves of pelvis and lower limbs (TII-L1)

dura mater

thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord (hard mother)

The longest nerve that innervates the digestive system is the:

vagus

The motor command leaves through the:

ventral root

spinal cord protected by

vertebral column and meninges

cranial reflexes

reflexes mediated by cranial nerves

central canal

CSF passes through

spinal cord

a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain. (31 segments)

anterior (ventral) gray horn

a section of gray matter that extends towards the anterior part of spinal cord, has motor neurons -somatic (skeletal muscle)

posterior (dorsal) gray horn

a section of gray matter that extends towards the posterior part of spinal cord, has sensory neurons -somatic (skeletal muscle) & visceral (organs)

patellar reflex (knee jerk)

reflex triggered by the knee tap 1. stretching stimulus sensory receptor (muscle spindle) 2. sensory neuron excited 3. within integrating center (spinal cord), sensory neuron activates motor neuron 4. motor neuron excited 5. effector (same muscle) contracts and relieves the stretching

anterior (ventral) ramus

serves the muscles and structures of the upper and lower limbs and the skin of the lateral and anterior surfaces of the trunk

Where in the spinal cord is the cerebrospinal fluid located?

subarachnoid space

cervical enlargement

supplies nerves to the shoulder and upper limbs (C4-T1)