anatomy unit 3

PNS is split into

sensory division and motor division

motor division is split into

somatic and autonomic

autonomic is split into

sympathetic, parasympathetic, and enteric

multipolar

multiple dendrites, one axon, ex. motor neurons and interneurons

bipolar

1 dendrite, 1 axon, sensory neurons like auditory, visual, vestibular neurons

pseudounipolar

peripheral process and central process, sensory non-bipolar like muscle spindles and cutaneous afferents

nerve

collection of axons/neuronal cell processes in PNS, will have supportive cells (schwann cells) and CT cells (fibroblasts)

tract

collection of axons/neuronal cell processes in CNS

ganglion

collection of neuron cell bodies in PNS

nucleus

collection of neuron cell bodies in CNS

groups of neurons

primary afferent neurons, final efferent neurons, interneurons, projection neurons

primary afferent neurons

conduct pulses from periphery to the CNS

final efferent neurons

conduct impulses from CNS to periphery, lower motor neurons, a,b, y, and autonomic

alpha final efferent neuron

intrafusal fibers in muscle spindle

beta final efferent neuron

extrafusal fibers in muscle spindle

y final efferent neuron

innervate both fiber types

primary afferent neurons and final efferent neurons together form _

reflex arcs/pathways

interneurons

short neurons interposed between afferent synpase and efferent cell body, completely in CNS, may be excitatory or inhibitory but synapses with both

withdrawal reflex

does not need pain, happens locally without brain involvment only spinal cord

projection neurons

in the CNS, can be ascending (spinal cord to brain) or descending (brain to spinal cord) which are known as upper motor neurons

functional types of neurons

based on region of body supplied: GSA, GSE, GVA, GVE

based on direction of impulses: SSA, SVA, SVE

general somatic efferent

multipolar neurons that supply most skeletal muscles, extends ffrom CNS to muscle fibers

general visceral efferent

multipolar neurons that supply smooth muscle, cardiac muscle, and glands, form autonomic nervous system, have two neuron chain between CNS and effector organ

special visceral efferent

multipolar neurons that supply skeletal muscle that are derived from branchial arches (face, neck, shoulders), single neuron from CNS to muscle fibers

general somatic afferent

pseudounipolar neurons that carry sensory info from somatic body systems, cell bodies in sensory ganglia/dorsal root ganglia

general visceral afferent

pseudounipolar neurons that carry sensory info from visceral body systems, cell bodies in sensory ganglia/dorsal root ganglia

special somatic afferent

bipolar neurons that carry visual and auditory information

special visceral afferent

bipolar and pseudounipolar neurons that carry taste and smell information

_ join to form spinal nerve that divides into _

dorsal root and ventral root, dorsal branch, ventral branch, and communicating branch

dorsal and ventral roots are broken down into _

rootlets

_ pairs of spinal nerves

31

cervical spinal nerves

8 pairs, cranial to corresponding vertebrae

thoracic and lumbar spinal nerves

13 and 7 pairs, caudal to corresponding vertebrae

where does c1 come from

lateral vertebral foramen

sacral spinal nerves

3 pairs, from dorsal and ventral sacral foramina

_ pairs of cranial nerves

12

what is the main nerve with autonomic system?

general visceral efferent, but also general visceral afferents and hypothalamus

autonomic

self rule, controls smooth muscle, cardiac muscle, and glands, 2 neuron system, originates in lateral horn of cranial nuclei, target is visceral organ, neurotransmitters are Ach and NE

somatic division

general somatic efferent, 1 neuron system, originates in ventral horn, target is skeletal muscle, neurotransmitter is Ach

sympathetic division

2 neurons, short-long, originates in lateral horn of thoracolumbar segments of spinal cord, neurotransmitters are Ach and NE, ganglia is chain/paravertebral or prevertebral

pre-vertebral ganglia

will be long-short

parasympathetic division

2 neuron system, long-short, originates in cranio sacral region, has brain stem and spinal cord nerves, neurotransmitters are Ach and Ach, ganglia is terminal (in body wall)

brain stem nerves of parasympathetic system

III - ocular motor, VIII - facial, IX - glossopharyngeal, X - vagus

sacral spinal cord nerve of parasympathetic

pelvic nerve

sympathetic actions with no parasympathetic pair

glucose production by liver, renin secretion by kidney, muscle vessels dilation, constriction of cutaneous and visceral vessels, contraction of piloerector muscles, secretion of sweat glands, lipolysis of adipose cells, adrenal medulla epinephrine secretion

sympathetic vs parasympathetic for eye/pupil, heart, lung bronchioles, gut wall, gut sphincter, bladder detrusor, bladder-urethra smooth sphincter, penis, gallbladder bile & duct, salivary glands, nasal and lacrimal glands

dilation vs constriction, increased rate and force vs decreased rate, dilation vs constriction, decreased motility vs increased motility, constrict vs relax, relax vs contraction, constrict vs relax, ejaculation vs erection, relax vs contract, concentrated viscous saliva vs abundant watery saliva, vasoconstriction vs abundant secretion

rami communicantes/communicating branch

connects spinal nerves to the sympathetic trunk, can be white rami or gray rami

white rami

preganglionic sympathetic axons, only with T1-L2 nerves, whitish due to myelination, similar to entrance ramps on highway

gray rami

postganglionic sympathetic axons, connect to all spinal nerves, grayish due to unmyelinated axons, similar to exit ramps off highway, disperses sympathetic info from thoracolumbar to all body parts

4 ways preganglionic neurons can connect with postganglionic neurons

spinal nerve pathway, post-ganglionic sympathetic nerve pathway, splanchnic pathway, adrenal medulla pathway

what is unique about sweat glands?

they are cholinergic in sympathetic, so neurotransmitters are Ach and Ach

spinal nerve pathway

preganglionic neuron comes from lateral horn out of ventral root, comes through white ramus, then synapses with postganglionic neuron that travels through gray ramus, goes back into spinal nerve, then goes to target tissue

post ganglionic sympathetic nerve pathway

synapses in chain gang, does not go back to spinal nerve, comes out of the ganglia

splanchnic nerve pathway

long pre synaptic neuron that goes through white ramus and synapses in prevertebral ganglion, primarily for visceral organs

adrenal medulla pathway

2 neuron system, synapse in adrenal medulla with post-ganglionic neuron as chromaffin cells that secrete epinephrine and norepinephrine

where are cell bodies of parasympathetic preganglionic neurons?

brain stem nuclei and lateral gray matter of 1st through 3rd sacral segments of spinal cord

ciliary ganglia

near optic nerve, oculomotor preganglionic eyeball muscles

pterygopalatine ganglia

near sphenopalatine foramen, facial preganglionic, nasal mucosa, palate, pharynx, lacrimal glands

four ganglia pairs of parasympathetic cranial outflow

ciliary, pterygopalatine, submandibular, otic

submandibular ganglia

near submandibular ducts, facial preganglionic, submandibular and sublingual glands

otic ganglia

below foramen ovale, glossopharyngeal, preganglionic, parotid glands

vagus nerve

has terminal ganglia so synpase in target organ, preganglionic axons here carry 80% of craniosacral outflow

what all do preglanglonic axons of vagus nerve innervate?

heart, lungs, liver, gallbladder, stomach, pancreas, small intestine, and part of large intestine

sacral parasympathetic outflow

has preganglionic axons from S1-S3 that form pelvic splanchnic nerves

what all do postganglionic axons of pelvic nerve innervate?

colon, ureters, bladder, and reproductive organs

sympathetic innervation to body wall and limbs

preganglionic from lateral horn, will exit out of ventral root and go through spinal nerve and communicating branch and synapse in sympathetic trunk

sympathetic innervation to head, neck, and thorax

preganglionic nerve will enter communicating branch then chain gang and then

• thorax: synpase at cervicothoracic ganglion

• neck: go around axillary artery as ansa axillaris, and synapse at middle cervical ganglion

• head: go around axillary artery as ansa axillaris, go through vagosympathetic trunk, and synapse at cranial cervical ganglion

ansa subclavia

loop around subclavian artery, cardiac nerves come off of it

sympathetic innervation to abdominal cavity

will go through communicating branch and chain gang, will leave as

1. caudal abdominal cavity: lumbar splanchnic nerve and synapse at caudal mesenteric ganglion

2. abdominal cavity: major and minor splanchnic nerves and synapse at celiacomesenteric ganglion and plexus

sympathetic innervation to pelvic cavity

will go through communicating branch and chain gang, will leave as lumbar splanchnic nerve and synapse at caudal mesenteric ganglion, post ganglionic nerves are vertebral and hypogastric nerves that will go through the pelvic plexus

parasympathetic innervation to head, cervical, thorax, and abdomen

vagus nerve will split into dorsal and ventral branch, R and L dorsal branches will make a dorsal vagal trunk that goes towards celiacomesenteric plexus, R and L ventral branches make a ventral vagal trunk that goes towards cranial mesenteric plexus

parasympathetic innervation to pelvic cavity

will leave lateral horn and go through ventral root, go through spinal nerve and lumbosacral plexus, leave as pelvic nerve and go through pelvic plexus

what does celiac plexus control?

stomach, spleen, liver, gallbladder, pancreas

what does cranial mesenteric plexus control?

small intestines, cecum, ascending and transverse colon

what does ventral vagal nerve trunk control?

liver and stomach

arterial supply of thoracic limb

subclavian artery → axillary artery → brachial artery → median artery → superficial palmar arch → palmar common digital arch

when does axillary artery become brachial artery?

after cranial circumflex humeral artery comes off

what does caudal circumflex humeral artery supply blood to?

latissimus dorsi

when does brachial artery become median artery?

after common interosseous artery comes off

what is superficial palmar arch formed by?

median artery and superficial branch of caudal interosseous artery

what conects the cephalic vein and the axillary vein?

axillobrachial vein

what connects the cephalic vein and the brachial vein?

median cubital vein

afferent lymph vessels

bring unfiltered lymph from the body to lymph node where it is filtered

efferent lymph vessels

carry filtered lymph to another lymph node, vein, or to a larger lymph duct

terminal lymph node

lymph node which all or most of lymph from a region must drain

sentinel lymph node

first node that drains a particular area and thus the node that is likely to be removed or biopsied in the event of neoplasia/infection

superficial cervical lymph node location

cranial to shoulder joint, covered by brachiocephalicus and omotransversarius

superficial cervical lymph node afferent lymph vessels

skin of caudal portion of the head, part of the ear, lateral surface of neck, most of thoracic limb except for medial side of arm, forearm, and shoulder

superficial cervical lymph node efferent lymph vessels

thoracic duct on left side, right tracheal trunk on right side, external jugular vein on both sides

axillary lymph node location

caudal to shoulder joint, ventral to thoracodorsal vessels and latissimus dorsi, at distal part of teres major muscle

axillary lymph node afferent lymph vessels

first three mammary glands, skin of shoulder and arm, all of bones except digits, humeral, cubital and carpal joints, muscles of thoracic limb, accessory axillary lymph node

axillary lymph node efferent lymph vessels

external jugular vein on both sides, thoracic duct on left side, right and left tracheal trunk

accessory axillary lymph node location

ventral to latissimus dorsi, dorsal to deep pectoral, in the 2nd and 3rd intercostal space

accessory axillary lymph node afferent lymph vessels

first three mammary glands, skin of lateral and ventral thoracic wall, lateral and medial regions of the shoulder, arm, and elbow

accessory axillary lymph node efferent lymph vessels

axillary lymph node

brachial plexus

made up of nerves from C6 - T2

nerves of brachial plexus

suprascapular, subscapular, cranial pectoral, musculocutaneous, axillary, thoracodorsal, radial, median, ulnar, lateral thoracic, caudal pectoral

nerves of brachial plexus that have cutaneous branches

musculocutaneous, axillary, radial, median, ulnar

all brachial plexus nerves have axons for _ and _, and all have _

sensory info and motor info, sympathetic fibers

muscles innervated by suprascapular, subscapular, cranial pector, musculocutaneous, axillary, thoracodorsal, radial, median, ulnar, lateral thoracic, caudal pectoral

• supraspinatus, infrapspinatus

• subscapularis

• superifical pectorals

• biceps brachii, brachialis, coracobrachialis

• deltoid, teres major, teres minor, (subscapularis)

• latissimus dorsi

• triceps brachii, extensor carpi radialis, ulnaris lateralis, common digital extensor, lateral digital extensor

• flexor carpi radialias, superficial digital flexor, (deep digital flexor)

• flexor carpi ulnaris, deep digital flexor

• cutaneous trunci muscles and reflex

• deep pectoral