Functional Human Anatomy Exam 2 Material

Cervical Plexus

innervates neck & diaphragm

nerve roots from C1 to C4 (sometimes contribution from C5) spinal nerves

Brachial Plexus

innervates pectoral girdles & upper limbs

nerve roots from C5 to T1 spinal nerves

Lumbar Plexus

innervates lower limb & pelvic girdle

nerve roots from T12 to L4 spinal nerves

Sacral Plexus

innervates lower limb & pelvic girdle

nerve roots from L4 to S4 spinal nerves

Nerve Plexus

network of nerves originating from ventral rami of the spinal cord (branches that extend from the spinal nerves after they emerge from the spinal cord)

Spinal Nerve Groupings

8 pairs of cervical spinal nerves

12 pairs of thoracic spinal nerves

5 pairs of lumbar spinal nerves

5 pairs of sacral spinal nerves

1 pair of coccygeal spinal nerves

31 pairs total

Spinal Nerve Components

dorsal and ventral roots come together to form a spinal nerve, which further splits into a dorsal ramus & a ventral ramus

Dorsal Root Fibers

only sensory incoming fibers

Ventral Root Fibers

only motor outgoing fibers

Dorsal Rami

takes in sensory signals from skin of your back & sounds out motor signals for back muscles

sends fibers to and from skin of back, deep back muscles, and joints between adjacent vertebrae

Ventral Rami

take in sensory signals from everything besides skin of back & sends out motor signals to all plexuses

Type of Fibers in Spinal Nerve

both sensory & motor

remember that a spinal nerve is formed from ventral & dorsal roots combining

spinal nerve divides laterally into dorsal & ventral rami

Rami Fibers

both ventral and dorsal ramis have sensory AND motor fibers

it is the roots that only have one of each (dorsal = sensory & ventral = motor)

Plexuses are nerves formed by?

ventral rami of our spinal nerves

Nerves from Cervical Plexus

Lesser Occipital Nerve

Ansa Cervacalis

Greater Auricular Nerve

Transverse Cervical Nerve

Phrenic Nerve - sensory & motor for diaphragm

Supraclavicular Nerve

Nerve to Rhomboids & Serratus

Cranial Nerves (CN XI accessory & CN XII hypoglossal)

Terminal Nerves from Brachial Plexus

Musculocutaneous Nerve 

Axillary Nerve

Median Nerve

Radial Nerve

Ulnar Nerve

MAMRU ABBREVIATION

These Terminal Nerves continue down the upper limb for a considerable distance. They are providing motor innervation to the muscles of the upper limb. They provide sensory innervation to the skin of the upper limb

Nerves from Lumbar Plexus

Iliohypogastric Nerve

Ilio-inguinal Nerve

Lateral Femoral Cutaneous Nerve

Genitofemoral Nerve

Femoral Nerve - supplies quad muscles

Obturator Nerve - supplies groin muscle

Sacral Plexus Nerves

Superior/Inferior Gluteal Nerves

Sciatic Nerve - largest nerve in the human body

provides motor innervation to muscles of foot, leg, and posterior thigh & sensory innervation to the same areas

splits into two along popliteal fossa (back of the knee): tibial & common fibular nerves

Posterior Femoral Cutaneous Nerve

Pudendal Nerve

Piriformis Muscle

small muscle in deep gluteal region 

sits right on top of sciatic nerve, so tightness of this muscle can impinge the nerve, which results in sciatica (weakness/pain in legs or parasthesia - tingling, numbness, or burning in the skin)

5 Major Regions of Brachial Plexus

Brachial Plexus originates from the ventral rami of spinal nerves C5-T1

Regions Medial to Lateral (Read The Darn Cadaver Notes): 

Ventral Rami of Spinal Nerves (Roots of Brachial Plexus) - Trunks - Divisions - Cords - Terminal Nerves

Brachial Plexus Trunks

3 trunks within brachial plexus 

superior trunk forms from C5 & C6 ventral rami

middle trunk forms from C7 ventral rami

inferior trunk forms from C8 & T1 ventral ram

Brachial Plexus Divisions

each trunk (inferior, middle, superior trunks) splits into two divisions (anterior & posterior divisions)

Brachial Plexus Cords

all three posterior divisions combine to form posterior cord

anterior divisions from superior & middle trunks form the lateral cord

continuation of anterior division of inferior trunk forms the medial cord

Brachial Plexus Nerves (FORMATION, not the actual nerves)

nerves of brachial plexus arise form one or more trunks/cords

Dermatome

an area of skin supplied by a single sensory nerve root

there can be significant overlap between adjacent dermatomes

Reflex

immediate involuntary motor response/action

Steps of Reflex Arc

reflex arc - neural wiring of single reflex - no conscious control

begins @ sensory receptor and ends @ peripheral effector

1 - stimulation & activation of sensory receptor

2 - activation of a sensory neuron - sends signal in from dorsal root/horn

3 - information processing in CNS - interneuron sends message through to motor neuron immediately, does not wait for brain signaling

4 - activation of a motor neuron - impulse sent out via ventral root/horn

5 - response by effector

Stretch Reflex

particular form of reflexes

occurs when a muscle is stretched and creates an involuntary motor response

muscle spindles in a muscle initiate stretch reflex

clinically, this is usually created by striking a muscle with a reflex hammer (patellar reflex!)

process:

1. stimulus activate sensory receptors & muscle spindle fibers are stretched

2. activation of a sensory neuron

3. information processing in CNS

4. activation of the motor neuron

5. response by effector - muscle contracts

Muscle Spindles

initiate stretch reflex

sensory receptors inside of our muscles that detect when a muscle is stretched

help to prevent overstretching of a muscle and help to maintain posture of the body, especially when supporting large loads

Meningeal Layers of Brain (superficial to deep)

Epidural space - dura mater - subdural space - arachnoid mater - subarachnoid space (CSF) - pia mater

Brainstem structures (inferior to superior)

medulla oblongata

pons

midbrain (mesencephalon)

Six Major Regions of Brain

Cerebrum, Cerebellum, Medulla Oblongata, Pons, Mesencephalon, Diencephalon

Medulla Oblongata

most inferior segment of brainstem

connects brainstem with spinal cord

essential to survive - plays a role in regulating visceral functions like cardiovascular system impulses

Pons

middle section of brainstem

allows for communication between cerebrum & cerebellum

several cranial nerves emerge here

Mesencephalon (midbrain)

most superior segment of brainstem

maintains consciousness

motor pathways; alertness; vision & hearing regulation

Cerebrum

two hemispheres (left & right) split by longitudinal tissue connected by corpus callosum (white matter)

controlateral control (opposite side)

sensory processing & motor output to skeletal muscles

conscious thought processes - logic, reasoning, planning

memory storage

Cerebral Cortex

gray matter of cerebrum

gyri - wormy-like formations of brain

sulci - crevices between gyri

Four Lobes of Cerebrum

Frontal - mainly motor output - higher coginitive functions, planning, reasoning, and memory - primary motor cortex: initiates voluntary movement

Parietal - sensory input mainly - primary somatosensory cortex: processes touch

Temporal - processing info from hearing (speech & language comprehension) - olfactory (smell) & gustatory (taste) cortex

Occipital - visual cortex

Central Sulcus

splits precentral (frontal) & postcentral (parietal) region

Cerebellum

little brain

balance; coordination; smooth, controlled motor function/movement

get info from visual & auditory cortex to help with balance

Diencephalon

superior to brainstem

attaches brainstem to cerebrum

3 divisions - epithalamus, thalamus, and hypothalamus divisions

Epithalamus Division of Diencephalon

has pineal gland (endocrine): secretes melatonin which regulates sleep cycles

acts as a bridge between limbic system and other parts of the brain

Thalamus Division of Diencephalon

sensory information relayed & processed here

Hypothalamus Division of Diencephalon

hormonal release

connection between the nervous and endocrine systems

intimate connection to pituitary gland - sends out regulatory hormones to it

controls emotion, autonomic functions, and hormone production

Basal Ganglia

a series of deeply located brain structures that coordinate movement in the body

receive info from cerebrum and brainstem

Limbic System

group of structures that regulate emotions - emotional brain

limbic structures:

• olfactory bulb & tract - sense of smell

• amygdala - memory, decision makaing, emotion

• hippocampus - memory & learning

• thalamus

• hypothalamus - connects endocrine & nervous systems

LABEL

label sagittal section through brain

label coronal section through brain

Ventricular System of the Brain

hollow spaces and channels that contain and move cerebrospinal fluid (CSF)

help to cushion and nourish the brain

general flow of CSF is moving down in an inferior diection

Chronological Passageway of CSF in Ventricular System

CSF produced by choroid plexus (specialized tissue made up of ependymal cells lining ventricles) in the two lateral ventricles found in cerebral hemispheres

CSF flows from lateral ventricles through interventricular foramina into third ventricle

CSF passes through narrow cerebral aqueduct into fourth ventricle

CSF is further produces in fourth ventricle by choroid plexus

CSF exits ventricle through three openings into subarachnoid space

CSF production

made by ependymal cells of choroid plexus

Cranial Nerves

12 pairs of them

general rule: as you increase in cranial nerve number, you are heading farther posteriorly and inferiorly

CN I

Olfactory Nerve

sensory only

sense of smell

CN II

Optic Nerve

sensory only

taking in visual information

CN III

Oculomotor Nerve

motor; controlling muscles that move eyeball superiorly, inferiorly, medially

one of three nerves that control extra-ocular muscles

CN IV

Trochlear Nerve

motor; controlling muscles that move eyeball superiorly

one of three nerves that control extra-ocular muscles

CN VI

Abducens Nerve

motor; controlling muscles that move eyeball laterally

one of three nerves that control extra-ocular muscles

CN V

Trigeminal Nerve

both motor & sensory

sensation to face

motor innervation of mastication (chewing)

CN VII

Facial Nerve

sensory & motor

muscles of facial expression, part of tongue (anterior 2/3 of it for taste), salivary glands

vulnerable during removable of parotid gland (near ear)

CN VIII

Vestibulocochlear Nerve

sensory only

2 divisions: vestibular & cochlear divisions

vestibular division: balance & sense of position in space

cochlear division: auditory input

CN IX

Glossopharyngeal Nerve

sensory & motor

taste & swallowing functions

sensory for posterior 1/3 of tongue for taste

controlling muscles for swallowing and speech

CN X

Vagus Nerve

sensory & motor

longest and most complex cranial nerve

primarily heart & digestive regulation through parasympathetic nerve signaling

CN XII

Hypoglossal Nerve

motor only

muscles of tongue (except palatoglossus, which is innervated by vagus)

when affected, tongue will deviate to one side when projected forward

CN XI

Accessory Nerve

motor only

innervates sternocleidomastoid & trapezius

neck & back movement

Autonomic Nervous System

functions outside of our conscious awareness

controls all actions occurring in the background to keep the body working normally

oversees cardiovascular, respiratory, endocrine, urinary, digestive, and reproductive functions

has both efferent & afferent nerve fibers

Efferent Portion of ANS

sends signals to our internal organs

has two divisions

1. sympathetic - fight or flight

2. parasympathetic - rest & digest

Afferent Division of ANS

visceral sensory receptors within internal organs

send information about internal environment to body

Somatic Nervous System

sends fibers to and from the skeletal muscle, our skin, and major joints

has efferent & afferent neurons

somatic motor neruons do not involve ganglia

Vital Functions of Autonomic Nervous System

• stimulates smooth muscle found in body’s organs and blood vessels

• influences glandular activity (upregulating/downregulating)

• acting upon the conducting tissue of the heart

• transmitting reflex & pain signals (sensory) information from organs, blood vessels, etc

• influences lung & heart activity

• influences activity of digestive tract

Sympathetic NS

fight or flight

energy consuming

essential for responding to internal and external stresses

AKA thoracolumbar division

Parasympathetic NS

rest and digest

energy conserving

essential for maintaining bodily functions during low activity and stress

AKA craniosacral division

Ganglia

essential element of the physical setup of the autonomic pathways

sympathetic & parasympathetic fibers rely on two neurons arranged in series

there is a preganglionic neuron and a postganglionic neuron

these neurons are in proximity at a ganglion

ganglion refers to clusters of neuronal cell bodies located outside the central nervous system

Preganglionic Neuron

short in sympathetic, long in parasympathetic

cell body is in the gray matter of the central nervous system

axons are within ganglia

Postganglionic Neuron

long in sympathetic, short in parasympathetic

cell body is peripherally located - outside CNS, inside ganglia

Sympathetic Ganglia

close to spinal cord

short preganglionic neuron that secretes acetylcholine (ACh) & long postganglionic neuron that secretes norepinephrine (NE)

Parasympathetic Ganglia

farther away from spinal cord

long preganglionic neuron that secretes ACh & short postganglionic neuron that secretes ACh

for the most part, these ganglia are adjacent to or within the walls of their effectors

Sympathetic Preganglionic Neurons

cell body originates in lateral horn of the gray matter in the spinal cord from T1 through L2 levels

Parasympathetic Preganglionic Neurons

cell body originates from cranial nerves III, VII, IX, X and from the sacral nerves S2-S4

Enteric Nervous System

3rd division of autonomic NS 

found in walls of the digestive tract

Sympathetic Ganglionic Neuron Location

sympathetic chain ganglia (paired) - target visceral effectors in thoracic cavity, head, body wall, and limbs through innervation by postganglionic fibers

collateral ganglia (unpaired) - target visceral effectors in abdominopelvic cavity through innervation by postganglionic fibers

adrenal medulla (paired) - target organs and systems throughout body through release of hormones in blood stream

Adrenal Medulla

the internally located part of the adrenal gland, which sits directly above kidneys

releases neurotransmitters epinephrine (adrenaline) and norephinephrine (noradrenaline) into bloodstream (no postganglionic neuron)

Sympathetic Stimulation Effects

increased alertness

a feeling of energy & euphoria

increased cardiovascular & respiratory activity

elevation in muscle tone

mobilization of energy reserves

Parasympathetic Stimulation Effects

constriction of pupils

secretion of digestive glands

secretion of hormones promoting nutrient absorption

increased smooth muscle activity along the digestive tract

stimulation & coordination of defecation

contraction of the urinary bladder during urination

reduction in heart rate and force of contraction

constriction of respiratory passageways

sexual arousal

Dual Innervation

most vital organs are innervated by both the sympathetic and parasympathetic divisions

two divisions often have opposite/antagonistic effects

label respiratory structures

Upper Respiratory Tract

nose, nasal cavity, paranasal sinuses, and pharynx

Lower Respiratory Tract

larynx, trachea, bronchi, lungs, bronchioles, and alveoli

Dividing Line between Upper & Lower Respiratory Systems

epiglottis

Conducting Zone

part of the airway from the nasal cavity going down towards the terminal bronchioles (full respiratory tract except for respiratory bronchioles & alveoli)

pathway is merely directing air down towards lungs

no gas exchange taking place in this part of pathway (this happens in alveoli)

filtration, warming, and humidification of inhaled air

Respiratory System Functions

provides an area for gas exchange between the air and the blood

moves air to and from exchange surfaces of the lungs

protects the respiratory surfaces from dehydration

provides protection against invading pathogens

produces sound involved in verbal communication

label black boxes of sagittal section of head and neck

Mucus (respiratory)

respiratory tract lined with epithelial tissue that secretes a sticky substance (mucus) which helps trap pathogens/dust/debris

epithelium is ciliated = has small fingerlike projections that move in a wavelike fashion

body wants to move the mucus upwards away from the longs

mucus can eventually be swallowed so the pathogens can be destroyed by the acidity in the stomach OR moved up to eventually be spit out

mucus plays a vital role in warming, humidifying, and filtering air within conducting zone in order to avoid damaging the delicate tissues farther down in the lungs

What view of the lungs is this?

anterior

What view of the lungs is this?

posterior

What view of the lungs is this?

lateral

3 lobes with transverse & oblique fissure - right lung

2 lobes with oblique fissure - left lung

Path of Air in Lungs

terminal bronchiole - respiratory bronchioles - alveolar ducts - alveolar sacs (visually resemble grape bunches)

alveolar sacs have numerous capillary beds which release carbon dioxide and then take on oxygen

oxygen is then distributed out to the body tissues

Bronchi Segments

primary, secondary, and tertiary segments

as you move deeper into lungs, you move into the tertiary segments

Major Cell Types that exist within lungs at alveolar level

Type I Alveolar Cells

Type II Alveolar Cells

Alveolar Macrophages

Type I Alveolar Cell

where gas exchange takes place in alveoli

form walls of alveoli