Anatomy Block 1 Lecture

anterior (ventral)

frontal view of the body

posterior (dorsal)

view of the back of the body

superior

towards the head, above smth

inferior

towards the feet, below or bottom of smth

proximal

closest to the trunk of the body

distal

furthest from the trunk of the body

rostral

toward/closer to the front/nose

caudal

toward or closer to the tail/back

how does blood flow through a capillary bed?

blood enters via the arterial side(has lots of smooth muscle) and leaves via the venous end

• arterioles along w/ precapillary sphincters constrict/dilate to control blood flow of capillary beds

• involves hydrostatic and colloid osmotic pressures

hydrostatic pressure

blood flows into capillary beds from arteriole end →push pressure that pushes OUT blood plasms along w/ dissolved nutrients and oxygen gases into the interstitial space, delivering it to tissue away from the brain supply (15-20 mg of Hg)

interstitial space

fluid filled gap between cells and tissue involved in capillary beds

colloid osmotic pressure

lower pull pressure that pulls water and proteins back in bc of positvely charged proteins creating an opposite charge

• HOWEVER, not all fluid gets pulled back in

importance of lymphatic vessels

• take left over fluid in the interstitium and bring it over to lymph nodes for them to filter, clean, and put it back into blood circulation via the venous system →preventing edema

edema

results when lymphatic vessels are blocked causing effected body area to swell bc of buildup of excess tissue fluid

neuron

nerve cell that receives, collects, and transmits info

• basic building block of the nervous system

structural neurons

multipolar, bipolar, unipolar, and pseudounipolar

multipolar

2+ processes; has many dendrites and 1 axon

• mostly found in the CNS: motor and intraneurons

bipolar

2 process; has 1 dendrite/sensory receptor and 1 axon

• rare: found in special sensory organs

unipolar

1 short/single process; no dendrites and one axon

• develops as a bipolar neuron first

• found in the PNS

pseudounipolar

axon branches into two

• one branch connected to dendrites (PNS) which recieve sensory info and the other is connected to the CNS

• sensory neurons

functional neurons

sensory (afferent) neurons, intraneurons, motor (efferent) neurons

sensory (afferent) neurons

transmit impulses to the CNS from sensory receptors in PNS

• bring in info via spinal chord or brain and then relay that info to an intraneuron

• activated by physical modalities or chem signals like visible light, sound, hear, physical contact, smell and taste

  • most are pseudounipolar

intraneuron

forms connection between sensory and motor (efferent) neurons

• located in the CNS

• operates locally as their axons connect w/ nearby sensory and motor neurons

• once they decide if info is critical, they talk to motor neurons and tell them to go out into the PNS and talk to an effector to get them to start movement

  • can save time and prevent injury by not sending messages all the way to the brain or not past the spinal chord

  • multipolar

motor (efferent) neurons

conducts impulses from integration center (CNS) to an effector

• body stays in the CNS but its axon goes into larger nerves in the PNS to talk to an effector to tell them to make muscle contraction happen

  • most common functional neuron

  • multipolar

effector

skeletal gland/muscle

glia (glial cells/neuroglia)

non-neuronal cells in the CNS and PNS that dont make electrical impulses but instead function as helper cells that aid in functioning

CNS neuroglia/glial cells

astrocytes, microglia, ependymal cells, and oligodendrocytes

astrocytes

protect and support neurons through feeding, regulation of ions, formation of synapses, growth and memory signaling

• sense when neurons release glutamate

• give energy by getting blood sugar from capillaries

• control environment around neurons by taking and releasing ions

• help form synapses in developing neural tissue

• produce molecules for neuronal growth

• send calcium signals involved w/ memory

  • most abundant glial cell in CNS

microglia

• are phagocytes (cells that engulf/digest random particles, debris, and dead cells)

• act as macrophages of CNS therefore are defensive cells that come from blood cells (monocytes)

• they move to the CNS during embryonic and fetal period

• smallest/least abundant glial cells in CNS

ependymal cells

line central cavity of spinal chord and brain

• have cillia which help circulate CSF

oligodendrocytes

produce myelin sheaths that wrap around axons in the CNS

• have few branches

PNS neuroglia

satellite cells and schwann cells (neurolemmocytes)

satellite cells

surround neuron cell bodies in ganglia to help w/ nutrient exchange

schwann cells (neurolemocytes)

surround parts of the axons to make myelin sheats in the PNS

skeletal muscle

act as pumps that press against veins (making them push blood toward the heart) since valves prevent backflow of blood (mostly in the lower limbs)

• 40% of body weight

• has striated cells

• controlled by voluntary division of the nervous system

• all are considered organs bc they have 2/4 tissue types: nervous, muscle, and connective-blood vessel

skeletal muscle structure

1. epimysium

2. fascicles

3. endomysium

4. muscle fiber

5. sacromere

6. myrofibrils

epimysium

thin/dense connective tissue membrane on the outside of the musce body

fascicle of muscle

bundle of muscle fibers wrapped in perimysium

endomysium

connective tissue membrane that covers muscle fibers(cells)

muscle fiber

individual muscle fibers/cells that are covered in endomysium

sacrolemma

plasma cell membrane of muscle fibers

myrofibrils

rod-like organelles in muscle cells in charge of contracting units

contraction and connective tissue of muscles

• connective tissue sheaths are connected to tendons and provide elasticity as well as carry blood vessels and nerves

• when muscle fibers contracts, force pulls on the connective tissues and pass onto the tendonds which then pulls on the bone itself

nerve structure

1. epineurium - outer membrane of the nerve body

2. fascicles - bundles of axons covered w/ perineurium membrane

3. axons covered w/ endoneurium membrane w/ blood vessels inside

intramembranous ossification

• bone formation directly from mesenchymal (no cartilage) at around 8 week of embryonic development (contiues during embryonic and fetal development)

• flat bones of the skull (except some base parts of it), mandible, along w/ the clavicles are formed

endochondral ossification

• begins during embryonic developement and CONTINUES during childhood and adolescence

• responsible for bone lenthening until epiphyseal plates close

• most bones of the skeleton including long bones (femure, humerus, tibia, etc.) along w/ short, irregular bones, vertebrae, pelvis, base of skull are formed by replacing a hyaline cartilage model

compact bone

smooth, solid, and dense outer layer of bone

• made of osteons

• makes up most of the diaphysis or shaft of long bones

• provides strength, protection, and weight-bearing

spongy bone (trabecular/cancellous bone)

honeycomb of small needle-like or flat pieces called trabeculae where red/yellow bone marrow is found

• found inside flat bones and inside the ends or epiphyses of long bones!

• helps reduce bone weight and resist stress

osteoporosis

low bone mass bc of bone reabsorption(breaking down) OUTPACING bone deposition(bone building)

• most common in women a4 menopause bc of the secretion of estrogens help maintain bone density

osteosarcoma

form of bone cancer

• normally originates in a long bone often near the knee

• common in 10-25 year old

• cancer cells come from osteoblasts-LIKE cells and secrets osteoid which alters affected bone by eroding medullary cavity internally and the compact bone externally

• often metastasizes to the lungs

• symptoms: bone pain and swelling, diagnosed X-RAY or imaging

• treatment: surgical removale (bone graft/prosthesis or amputation, chemotherapy, removal of lung metastases

• if detected early 60-70% chance of survival

osteoarthritis

common degenerative joint disease where there is detoriation of the articular cartilage; seen a lot in aging

• no synovial membrane(connective tissue that lines inside of synovial joints→ make synovial fluid to lubricate joint and fee cartilage) involvement but inflammation, pain and decrease in the use of the joint or present

gouty arthritis

metabolic disease where the waste product, uric acid (made by the cells and excreted through urine) is too much in quantity → builds up in the blood and makes salt crystals that stay in the joints causing pain and decreases motion

atherosclerosis

• when the arterial wall has plaque (lipid) buildup

• macrophages are transformed into foam cells as they try to get rid of the stuff

• plaque gets BEHIND the endothelium cells and builds WITHIN the wall →pushing int the lumen causing: localized inflammation, cellular necrosis, and increased shear pressure causing the wal to rupture leading to possible formation of thrombosis (clotting of blood)

  • risk factors include life factors and predisposition

lymph nodes

nodes that filter and clean excess fluids (esp from capillary beds)

• has immune cells (lymphocytes, macrophages) that detect and fight infections/cancer

sentinel nodes

nodes that are the frist to get lymphatic fluid from a speciifc area

• important bc often the first place cancer spread

• efficient for checking of matastasis

paired bones of cranium

symmetic on both sides; one on each side

• temporal bones

• parietal bones

unpaired bones of cranium

single bone; fall on the midsagittal line; not seprated by sutures

• frontal bone

• occipital bone

• sphenoid bone (looks like a bat, middle)

• ethmoid bone (between eyes, part of nasal cavity)

  • has perpendicular plate that drops inferiorly and forms the upper region of the septum of the upper nostrils

paired bones of the face

• maxillae

• zygomatic bones

• nasal bones

• lacrimal bones

• palatine bones

• inferior nasal conchae

unpaired bones of the face

• mandible - rare to see any abnormalities

• vomer - makes the inferior portion of the nasal septum and fuses w/ the perpendicular plate

CSF

cushions and nourishes the brain and spinal cord, removes waste made by neurons, and carries chm signals

• location: ventricles of the brain, subarachnoid space (between arachnoid mater and pia mater), central canal of spinal cord (little amt)

  • flows to the subarachnoid space via lateral and median apertures of the 4th ventricle

• production: made in the choroid plexus (roof of the ventricles), where modified ependymal cells covered by capillary rich pia mater filter blood plasma and make CSF

• reabsorption: goes into dural venous sinuses (i.e superior sagittal sinus) via arachnoid granulations → into bloodstream

  • abt 500mL/day is produced and recycled

hydrocephalus (water on the brain)

excessive accumulation of CSF →increase intracranial pressure

• cause of excess production of CSF or inadequate recycling of CSF (idiopathic and or congenital)

  • also can be caused bc of tumor/ swelling →blocking cerebral aqueduct/4th ventricle, blocking of arachnoid granulations (post meningitis bc of scarring), or bc of overdeveloepd choroid plexus in infants causing excess secretion

• infants have enlarged skull/ventricles bc cranial bones aren’t fused yet and adults are susceptible to quick damage bc bones are rigid

• treatment: surgical shunt to drain CSF from ventricles into the abdominal cavity

• diagnosed via CT or MRI scan

meningitis

inflammation of the meninges due to bacterial or viral infection whcih can spread to nervous tissue and cause brian inflammation (encephalitis)

• diagnosis: CSF sampling via lumbar puncture (spinal tap)

  • needle inserted below L1-L2 (common: L3-L4 or L4-L5)

  • look for microbes, chemicals, or pressure

• bacterial infection cause - releases metabolic waste/proteins into CSF

  • antibiotic treatment

• viral infection cause → non living, need a host cell to reproduce (viral rna takes over nucleus and makes more viruses.) once cell is full →becomes dead and leaves cellular debris(cell membrane fragments) are left in CSF

  • antiviral treatment

4 regions of the brain

1. cerebrum

2. diencephalon/thalamus

3. brainstem

4. cerebellum

cerebrum

consists of the cerebrum hemispheres (83% of brain mass), and the olfactory and optic nerves

• has lots of fissures (deep grooves that seperate major parts of the brain) including the transverse fissure which seperates the cerebrum from the cerebellum (top/bottom division) and the longitudinal fissure which separates the cerebral hemispheres (left and right division)

• also has sulci(grooves on the surface of hemispheres or the valleys between) and gyri (twisted ridges between sulci (top of the mountain)

• has 4 lobes: frontal, parietal, occipital, temporal, and a hidden lobe - the insula (deep lobe underneath the frontal, temporal, and parietal lobes

diencephalon

• made of the hypothalmus, thalamus, epithalamus, subthalamus, penial, and pituitary glands; center of the brain

  • mostly made up gray matter and intraneurons that recieve messages and relay them

• relay area of the brain: 90% of everything that goes into the brain is processed here

• the thalamus acts as a receptionist as thats where messages come through and get “transferred”

hypothalamus

• located below the thalamus in the diencephalon and between optic chiasma and mamillary bodies

• helps form walls of 3rd ventricle

• connected to the pituitary gland

• regulates homeostatic functions like sweating (body temp reuglation), eating (hunger/thirst), reproductive, growth, emotional responses, control of behavior, regulation of sleep-wake cycles, formation of memory

• recieves info from the thalamus

• generates messages

• controls the endorcrine system

• controls ANS (parasympthatic and sympathetic)

• if damaged → severe weight loss/obesity, sleep disturbances, dehydration, and emotional disorders

epithalamus

• dorsal part of the diencephalon

• forms part of the top of third ventricle

• made up of a tiny group of nuclei and the pineal gland which comes from ependymal glial cells and secretes melatonin hormone for night time under the influence/control of the hypothalamus

thalamus (inner room)

• 80% of diencephalon and walls of the third ventricle

• dozen major nuclei that send axons to regions of the cerbral cortex and either amplify or tone down signals

• relay station for incoming sensory messages

  • every part of the brain that communicated w/ cerebral cortex relays signals through the thalamic nuclei

  • receives afferent impulses (signals from the PNS)

  • gateway to the cerebral cortex

brain stem

made of the the midbrain, pons, and medulla - connected to the spinal cord

• 10/12 pair of cranial nerves are found here - involved w/ innervation of face and head

• production of autonomic behavior important for survival i.e parasympathetic (rest and digest) and sympathetic (fight or flight)

• has auditory and visual reflexes

• all nerve fibers (axons) that branch off the spinal cord reach the cerebrum via the brain stem

medula oblongata

most caudal part of brain stem

• decussation of pyramids - cross over of motor tracks (left side of the brain controls the right side of the body and vice versa)

• 4 CN :

  • VIII vestibulococlear

  • IX glossopharyngeal

  • X vagus

  • XII hypoglossal

• symmetrical and has lots of nuclei or visceral centers that each control different process: cardiac center, vasomotor center, respiratory center, hiccuping, sneezing, swallowing, and coughing center (inhibiting and stimulation)

• important for autonomic function

pons

bridge betwee medulla and midbrain

• has 3 CN:

  • V trigeminal

  • VI abducens

  • VII facial

• has motor tracts coming from the cerebral cortex

midbrain

• between the diencephalon and the pons

• cerebral aqueduct

• has big red/brown pigmented nuclei that work to together regarding specific processes

  • red nuclei - control limb

  • brown nuclei (substantia nigra) - neuronal cells bodies that make dopamine and have lots of melanin which is important for coordinated body movements and limb control

    • if uncontrolled → Parkinson’s disease (cell death in substantia nigra)

• posteriorly has two little bumps called corpora quadigemina (4 bodies organized in a square pattern) which are important for visual via superior colliculi, which jerk head in response to flashing lights and sound via inferior colliculi which jerk head in response to a loud sound

cerebellum

“little brain on top of the big brain” that helps maintain equillibrium and smoothly coordinate body movements through communication w/ dopamine neurons in the substantia nigra

• dorsal to pons and medulla

• arbor vitae - lots of white/light brown matter

• 2 cerebellar hemispheres w/ surface folded into folia (ridges)

• 3 total regions: cortex - gray matter, arbor vitate, internal white matter

• 3 lobes: anterior, posterior, and flocculonodular lobes

brain tumors

• can grow in many different parts of the brain

• symptoms vary depending on size and location

  • frontal lobe tumor → behavior changes

  • thalamus tumor → disruptions in hormonal secretions

  • cerebellum tumor → difficulty in movement coordination

• most dont metastasize bc of blood brain barrier

  • cancer cells from body can enter the brain via bloodstream → secondary brain tumors

  • not common for cells from the brain to go outside of CNS

facial artery and cavernous sinus’ role in encephalitis and meningitis development

• facial vein is connected w/ the angular vein which is connected to (has anastomoses) with w/ the superior ophalmic vein

• superior ophalmic vein drains intro the cavernous sinus(important for blood drainage) and allow bidirectional blood flow further allowing infections to spread from the face throughout the veins

• bacteria that enters sinus can lead to cavernous sinus thrombosis and potentially lead to meningitis/encephalitis

CN locations and characteristics

• pairs found in ventral aspect

• CN I olfactory and CN II optic come from middle/optic chiasm

• 10 other pairs come from brain stem

• CN X vagus is the largest nerve

• pass through foramina

CN 1 olfactory

location - nasal cavity

function - smell

type - visceral sensory

• anosmia: loss of smell sense bc of ethmoid bone fracture or olfactory fibers lesions

CN II optic

location - eye retina

function - vision

type - special somatic sensory

CN III oculomotor

location - eye muscles (ventral midbrain)

function - eye movement inside of eye, iris constricting, lens shape (4/6 intrinsic and 2/6 extrinsic muscles)

type - somatic and visceral motor

CN IV trochlear

location - superior oblique

funciton - eye movment

type - somatic motor

CN V trigeminal

location: jaw/face

function: facial sensation; chewing

three branches: 1. ophalmic 2. maxillary 3. mandibular

type: both

• sensory nerve of the face regarding touch, temperature, and pain

• mandibular branch has somatic motor control of chewing muscles

• innervated muscle of maastication

CN VI abducens

location: lateral rectus muscle
function: eye movement outward
type: somatic motor

CN VII facial

location: muscles of facial expression
function: facial movements and taste
three branches: temporal, zygomatic, buccal
type: both

CN VIII vestibulocochlear

location: inner ear(cochleal semicircular canals and vestible)
function: hearing and balance
type: sensory

CN IX glossopharyngeal

location: tongue/throat

function: taste, swallowing, saliva

type: both

CN X vagus

location: thoracic/abominal organs

function: parasympathetic control, voice, swallowing

type: both

CN XI accessory

location: neck, shoulder

function: head rotation, shoulder elevation

type - motor

CN II hypoglossal

location: tongue

function: tongue movement

type: motor

mimetic muscles

• scalp, eyelids, nasal, mouth

• control expression

• all motor innverated by CN VII facial nerve

• all sensory innervated by CN V trigeminal

scalp: epicranius (occipitofrontalis)

eyelids: orbicularis oculi (orbital palpebral/lacrimal), corrugator supercilli

nasal: nasalis

mouth: orbicularis oris, zygomaticus minor

zygomatic major, risorius w/ sygomaticus major, levator labii superioris, depressor labii inferioris, levator anguli oris, depressor anguli oris, buccinator, mentalis, platsyma

scalp mimetic muscles

epicranius - wrinkles in the forehead. astonishment

eyelid mimetic muscle

corrugator supercilli - vertical folks, protects against light, thinker’s brow

orbicularis oculi (orbital, palpebral/lacrimal) - lateral folds, concern

nasal mimetic bone

nasalis

mouth mimetic muscles (zygomatic)

zygomaticus minor

• originates from zygomatic bone

zygomaticus major - lifts corners of mouth upwards, laughter/pleasure

• comes from zygomatic bone, corner of mouth

mouth zygomatic bones (levator/depressor)

levator labbi superioris - pulls on upper lip

• comes from infraorbital margin/skin of upper lip

depressor labii inferioris - pulls lower lip down, perseverance

levator anguli oris - lifts corners of mouth, self confidence expression

depressor anguli oris - pulls corners of mouth down, sadness

mouth mimetic muscles

risorius w/ zygomatic major - make nasolabial folds , laughing muscle

buccinator - blows air out mouth, keeps mucous membrane free from folds

• quadrilaterl shape

• originates from mandible (molar/cheek area)

• forms pterygomandibular raph, extends to angle of mouth, forms lateral wall of vestibule

mentalis - chin lip furrow, doubt/indecision

platysma - tenses anterior neck skin

clinical significance of TMJ

temporal mandiublar joint which is important for mastication, speech, swallowing, and facial movements (condyle and temporal bone)

TMJ syndrome

acute/chronic pain in the TMJ or mastication joint process (where condylar process and temporal bone meet)

• also can be inflammation masstication muscles which are innervated by CN V

  • constant pain → joint

  • pain while chewing → lateral pterygoid muscle

  • radiating pain across jaw → masseter

  • issues radiating into temporal region → temporalis

salivary glands

produce and release saliva into oral cavirt via stensens duct (parotid gland) includes parotid, submandibular, and sublingual

• chemical part of digestion

• all are innervated by CN VII facial and CN IX glossopharyngeal which controll parasympathetic and sympathetic innervation

parotid gland

• largest gland - infeiror to or underneath the zygomatic bone

• aka stensen’s duct

  • mumps

mumps

inflammation of parotid gland caused by myxovirus