A&P Chapter 12 Flashcards
Spinal Cord
- extends to 2nd lumbar vertebrae
- gives rise to 31 pairs of spinal nerves
- cervical enlargement: nerve fiber of upper limbs enter and exit (arm)
- lumbosacral enlargement: nerve fibers of lower limb exit and enter (leg).
Meninges
connective tissue membranes
Dura mater
superficial and thickest membrane
arachnoid mater
next deeper meningeal membrane
Pia mater
deepest, bound to the spinal cord.
Forms filum terminale( anchors spinal cord to coccyx)
White matter
myelinated axons; schwanns cells
Gray matter
cell bodies, dendrites, and unmyelinated axons.
White matter of spinal cord
- each half divided into 3 columns
- ventral
- dorsal
- lateral
- each funiculi divide to tracts of fasciuli
- white commissure: connect halves together.
Gray matter of the spinal cord
- organized into horns
- posterior
- anterior
- lateral
- gray commissure: connects halves
- central canal: helps circulate cerebrospinal fluid.
Roots of spinal cord
each half has a dorsal root an da ventral root. roots join laterally to form spinal nerve.
Dorsal root
sensory neurons (sensory info)
Ventral root
Autonomic neurons; motor neurons. glands and muscles
Neuron
basic structural unit of the nervous system
reflex arc
basic functional unit. ability to receive stimuli and produce response.
Reflexes
- Autonomic response
- some can be exaggerated (diff for everyone)
Consists of- sensory receptor
- sensory neruon
- interneuron
- motor neuron
- effector organ
Golgi tendon organs
- encapsulated nerved endings in tendons
- prevents excessive tension in tendons
Reciprocal innervation
- inhibitory signals sent to antagonist muscles
- reduces resistance to movement
cross extensor reflex
- stimulation of motor neurons in other leg
- aids in maintaining balance
Endoneurium
surrounds the individual nerve fibers
perineurium
surrounds groups of nerve fibers
fascicles
bundle of fibers encased in perineurium
epineurium
encases fascicles
Organization of spinal nerves
8 cervical C1-C8 12 thoracic T1-T12 5 Lumbar L1-L5 5 sacral S1-S5 1 coccygeal Co
Plexus
bundle of nerves
Dermatome
area of skin spinal nerve innervates
Dorsal Rami
innervates deep muscles of vertebral column.
Ventral Rami
innervate intercostals. Forms the 5 major plexus.
cervical plexus
originating form C1-C4 - innervates 1. skin of neck and posterior head 2. hyoid muscle 3. superficial neck structures - Phrenic nerve innervates diaphragm (branch of C4) ***
Brachial Plexus
- originates from C5- T1
- axillary nerve: deltoid, teres minor
- Radial nerve: supinator, upperlimb extensors, brachioradialis.
Musculocutaneous nerve
anterior muscles of the arm. Sensory fpr the forearm.
ulnar nerve
2 muscle of the forearm; intrinsic hand .
Median nerve
most flexors of forearm; hand muscles at the base of thumb.
Axillary nerve
- laterally rotate arm: teres minor
- abducts arm: deltoid
- Skin: inferior lateral shoulder
Radial nerve
movements at the elbow and wrist; thumb movements
- skin: posterior surface of the arm and forearm, lateral 2/3 of dorsum hand.
Musculocutaneous nerve
- movements at the shoulder, elbow and wrist
- skin: lateral surface of forearm.
Ulnar nerve
- movements at the wrist, fingers and hand
- skin: medial 1/3 of hand, little finger, and medial1/2 of ring finger
Medial nerve
- movement of the hand, wirst, thumb, fingers.
- Skin: lateral 2/3 of palm, thumb, index and middle fingers; lateral 1/2 of ring finger and dorsal tip of same fingers.
Other nerves pf the brachial plexus
pectoral, long thoracic, thoracodorsal, subscapular, and suprascapular.
Lumbar and sacral plexus
- Tibial nerve: posterior thigh, leg, and foot.
- fibula nerve: posterior thigh, leg, foot.
Lumbar and sacral nerves
lumbar originated L1-L4
sacral originates L4-S4
- obturator nerve: medial thigh and knee (adducts)
- femoral nerve: anterior thigh.
Gluteal nerve
hip muscles that act on femur
pudendal nerve
abdominal wall and anesthetized in childbirth.
external genitalia
- genitofemoral nerve, illoguinal nerve, illiohypogastric nerve, cutaneous femoral nerve.
Coccygeal plexus (least amount of nerves)
- formed at S5 and coccygeal nerve
- innervates
- pelvic floor
- skin over coccyx sends info.
Anesthesia
loss of sensation
Hyperesthesia
increased sensitivity to light, pressure, and pain
paresthesia
tingling, prickling, burning ( hand falling asleep)
Neuralgia
nerve inflammation causing stabbing pain
Sciatica
pain radiating down back of thigh and leg.
Herpes
skin lesions
shingles
or herpes zoster; adult disease of chicken pox
poliomyelitis
infantile paralysis
anesthetic leprosy
bacterial infection of the peripheral nerves
- can be caught from an armadillo
Myasthenia gravis
resultsin fatigue and muscular weakness due to inadequate ACH receptors.
