MSK: Back (7/20/20)

What are two folds that occur during embryonic development?

Lateral Fold Cephalocaudal fold (look these up on youtube)

What are two types of plates in the Lateral Plate Mesoderm?

Lateral Plate Mesoderm 1. Parietal (somatic) lateral plate 2. Visceral (splanchnic) lateral plate

What is the structure (kinda like a tunnel) through which the mesenchymal cells travel into the Lateral Plate Mesoderm?

Lateral Somitic Frontier (LSF)

Where is Stratum Lucidum?

Limited to the thick skin of *palms* and *soles*

What happens if the perched facet of a hyperflexion injury REALLY goes forward?

Locked Facet

What are two long bones? What are two flat bones? What are two irregular bones?

Long bones = femur, ulna Flat bones = scapula, sternum Irregular bones = sphenoid bone, vertebrae

What does the rough ER look like with staining?

Looks like a spongey, grainy, hazy bit that's stained basophilic region

How does a herniated IVD spinal nerve compression present?

Radiculopathy

What determines the color of skin?

Rate of melanogenesis (faster = darker skin)

Where is red marrow found in long bones? What process happens here?

Red Bone Marrow is found in the spongy bone Hematopoesis

We have segmentation with the formation of the somites, and then...

Regsegmentation of the Scleratome (vertebrae)

What is the structure that gives rise to the vertebral column called?

Scleratome

What do Sebeaceous Glands produce? Where are they primarily located?

Sebaceous Glands -produce *sebum* (like a sea bum, it's oily) -also produce *Holocrine* Located primarily at face and scalp

What are the three types of Muscle Tissue?

Skeletal, Cardiac, & Smooth

What is the Integumentary System?

Skin

If you want to sample the CSF in the Subarachnoid Space, which vertebrae should you aim between?

(Below Conus Medullaris) Between L3 & L4 or Between L4 & L5

What structure similar to the periosteum on the inner surface of the bone?

*Endosteum*

What domain of the Axial Skeleton gives rise to all of the other musculature?

*Abaxial Domain* gives rise to all of the other musculature

What is Achondroplasia? What gene causes it? What ossification is affected? What bone growth pattern is affected?

*Achondroplasia* -most common form of dwarfism -cartilage disorder in which cartilage growth and replacement by bone is impeded -any bones that develop by endochondral ossification are affected -any bones that grow via interstitial growth plates are affected -caused by a mutation in the *fibroblast growth factor receptor 3 gene (FGFR3)* -autosomal dominant *Large head presentation makes sense because the Intermembranous ossification is not affected*

How can the PNS be divided into the motor and sensory divisions? (name the two divisions)

*Afferent* = sensory division *Efferent* = motor division

Why are these considered connective tissues? Bone Cartilage Adipose Tissue Blood

*All of these have cells, fibers, and ECM* (fibers plus ground substance) Bone Cartilage Adipose Tissue Blood

What are all layers of the Epidermis composed of? What are the layers of the Epidermis? (5)

*All of these layers of the Epidermis are comprised of Epithelial Tissues* 1. Stratum Corneum 2. Stratum Lucidum 3. Stratum Granulosum 4. Stratum Spinosum 5. Stratum Basale/Stratum Germinativum

Regardless of type, ALL cartilage contains What type of collagen? What cells? What type of ground substance?

*All* cartilage contains: Collagen: type 2 collagen Cells: chondrocytes and chondroblasts Ground substance: gel-like ground substance

What is Amelia and Meromelia?

*Amelia* - early loss of FGF signaling *Meromelia* - late loss of FGF signaling

What are Amniotic Bands?

*Amniotic Bands* -amniotic membrane wraps around forming limbs/digits and causes local ischemia and/or inhibits tissue growth

What is Anencephaly?

*Anencephaly*, -failure of the cranial (anterior) neuropore to close between days 23-25, -usually only brainstem present, -little to no cerebrum develops

What is Ankylosing Spondylitis? Other than the spine, what major joint does it affect? What is the buzzword for what this looks like on x-ray?

*Ankylosing Spondylitis* -autoimmune disease -inflammation that leads to abnormal bony fusion Also affects the sacroiliac joint "Bamboo spine"

What do the words Ankylosing Spondylitis medically mean?

*Ankylosing* = union of 2 or more hard tissues into one *Spondylitis* = inflammation of vertebrae

As the limb is developing, what structure forms at the tip of the limb? What is this zone called?

*Apical Ectodermal Ridge (AER)* -"little nipple on ridge" -induces surrounding mesenchyme to proliferate rapidly -called the "Undifferentiated Zone"

What are the three surface types with Epithelial Tissue?

*Apical surface* - toward the surface *Lateral surface* - touching other cells *Basal surface* - touching basement membrane

What type of nerve fibers are found within the Osteon?

*Autonomic Nerve fibers* -so when it hurts when you break a bone, it's the nerves in the periosteum that are hurting, *not the bone itself*

What are the two divisions (plus 1) of the Visceral Efferent PNS (ANS)?

*Autonomic Nervous System* -Sympathetic -Parasympathetic -Enteric

What is a "Basement Membrane"?

*Basement Membrane* -found in most epithelial tissues -fibrous tissue on which the epithelial tissue rests -separates *epithelial tissue* above from *connective tissue* below

What is Bowhunter's Syndrome?

*Bowhunter's Syndrome* -compression of vertebral artery by an osteophyte from the uncinate process

What is a Bulged Intervertebral Disk? What is a Herniated IVD? What are the symptoms of each?

*Bulged IVD* -annulus is compromised, but has not been breached -symptoms: pain in region of IVD *Herniated IVD* -annulus has been breached -symptoms: paresthesisa (tingling) in dermatome, muscle weakness, diminished reflexes

What is a Burst Fracture?

*Burst Fracture* -Vertical (axial) loading -C3-C7 -posterior fragments may be in spinal canal -if posterior ligament is okay, then stable -unstable without posterior ligament

What class of Transmembrane Proteins do Adherens Junctions rely on? What is the function of those proteins?

*Cadherins* -anchors *actin filaments* of adjacent cells

What class of Transmembrane Proteins do Desmosome Junctions rely on? What is the function of those proteins?

*Cadherins*, like adherens junctions -anchors *intermediate filaments* of adjacent cells

For an organ, what do the following refer to? Capsule Cortex Medulla Parenchyma Stroma

*Capsule* - connective tissue enclosing an organ *Cortex* - outer portion of an organ *Medulla* - inner portion of an organ *Parenchyma* - general term for the functional components of an organ *Stroma* - general term for the structural components of an organ (s for structural)

All connective tissue has what three structures in common?

*Cells* (various types) *Fibers* - these are extracellular *Ground substance* - basically the stuff the cells and fibers are floating in

What is a Cervical Rib?

*Cervical Rib* -The costal element that is supposed to become the transverse process of CV7 turns into a rib instead

What chronic infection can occur in 20% of Situs Inversus patients? Why does this occur?

*Chronic Sinusitis*, -occurs from *abnormal cilia* throughout their respiratory system

What is a Clay-Shoveler's Fracture?

*Clay-Shoveler's Fracture* -avulsion spinous process C6, C7, T1 -stable -PLL intact = no neuro deficit -"ghost sign" - double spinous processes on AP view

What are Collagenous connective tissue Fibers like?

*Collagenous Fibers* -"Like a rope" -*type 1 and 2 collagen* -Very tough, but inelastic -form bundles near other collagen ex: tendon, ligament

What structures are surrounding the Osteon's central canal?

*Concentric Lamellae* of bone tissue -lamella just means "sheet"

What causes Congenital Scoliosis? What is the worst version of this?

*Congenital Scoliosis* -Hemivertebrae Worst version: Fully segmented, where vertebrae have not compensated at all

The neural tube, once it has formed fully, is open at the cranial and caudal ends. What are these openings called? What day do these openings close?

*Cranial (anterior) neuropore*, -close day 25, *Caudal (posterior) neuropore*, -close day 28, -(remember that development shifts from cranially to caudally, so the later closing of the caudal neuropore makes sense)

What is Degenerative Disc Disease (DDD)? What is the nerve that is primarily involved with this?

*Degenerative Disc Disease (DDD)* occurs when the IVD has a diminished nutrition with time due to changes in the *vertebral body end plate* -causes an increased innervation by the *Basivertebral nociceptive nerves*

What are three types of Dens Fracture?

*Dens Fracture* Type 1 = "tip of the Dens", at least one Alar Ligament compromised Type 2 = separation of Dens from body -no blood supply, so worst type Type 3 = fracture through the body -blood supply, so even though it looks worse, it's better than Type 2 Dens Fracture

What is the name for the structures that come off of the pia mater to securely attach it to the dura mater? Why are they called that?

*Denticulate Ligaments* -They are called that because they look like *little teeth*

What process does the top layer of Stratum Corneum undergo?

*Desquamation* (shedding) -proteolytic enzymes degrade the desmosomes between cells -allows top layer to slough off, shedding the skin cells

What does the Dorsal (parietal) Layer of the Lateral Plate Mesoderm differentiate into?

*Dorsal (parietal) Layer* -sternum -dermis of the body wall -parietal pleura and peritoneum -bones/connective tissues of the limbs

What are the three horns located in the Gray Matter of the Spinal Cord? How can you tell the orientation of the Horns?

*Dorsal Horn* - tends to project more superficially, even communicating with the surface of the spinal cord *Lateral Horn* *Ventral Horn*

Laterally from the spinal nerve, what travels posteriorly? What travels anteriorly?

*Dorsal Ramus* - travels posteriorly *Ventral Ramus* - travels anteriorly

What type of fibers are present in the Dorsal Root? Where are the cell bodies for those fibers?

*Dorsal Root* -afferent (sensory) fibers only -GSA -GVA The cell bodies for those fibers are located in the DRG -(remember the pseudounipolar neurons with their arms stretched out?)

What are two types of Sweat Glands? Where are they located? When do they secrete sweat? Are they associated with hair follicles? Lumen size? Type of epithelium? Functional at birth?

*Eccrine Sweat Glands* -distributed throughout the body -sweat secretion in response to heat -not associated with hair follicles -merocrine secretion -narrow lumen (*stratified cuboidal epithelium*) -functional at birth *Apocrine Sweat Glands* -distributed primarily in axilla -sweat secretion primarily in response to anxiety -secretion along hair follicle -wide lumen -*simple cuboidal epithelium* -functional at puberty

What are Elastic connective tissue Fibers like?

*Elastic Fibers* -thinner than collagenous -elastic -more wavy -ex: walls of large blood vessels

What is Encephalocele?

*Encephalocele*, -failure of the cranial neuropore to close between days 23-25, -can affect anterior or posterior skull

What is Endothelium? Example?

*Endothelium* - simple squamous epithelium that lines inner walls (lumen) of blood and lymph vessels ex: arteries/veins, lymphatics

What are the functions of the following types of nerves of the skin? Merkel's Corpuscle (epidermis) Meissner's Corpuscle Pacinian Corpuscle Ruffini's Corpuscle Krause's End Bulb

*Epidermis:* Merkel's Corpuscle - mechanosensation (light touch) Dermis: Meissner's Corpuscle - light touch (papillary layer) Pacinian Corpuscle - pressure/vibration (reticular layer) Ruffini's Corpuscle - stretch (reticular layer) Krause's End Bulb - cold/vibration? (reticular layer)

What are the two main spaces that exist within the meninges? What is contained within each of these two spaces?

*Epidural Space* - between dura mater and the vertebral canal -contains fat and blood vessels *Subarachnoid Space* - between pia mater and arachnoid mater -contains *cerebrospinal fluid (CSF)*

What is the end of the long bone called? What is the area of the long bone where it starts to widen? What is the shaft of the long bone called?

*Epiphysis* - end of long bone *Metaphysis* - where the bone starts to widen *Diaphysis* - the shaft of the long bone

What are two main TYPES of embryonic cells?

*Epithelial* cells and *Mesenchymal* (stem) cells

What are two types of embryonic cell transitions? How do the cells morphologically change in each?

*Epithelial-to-mesenchymal transition (EMT),* -cells lose polarity and become migratory, *Mesenchymal-to-epithelial transition (MET),* -cells gain polarity and form tight junctions of tubes and sheets

What are the two types of Melanin? Where are they found?

*Eumelanin* -found in skin and hair -black/brown *Pheomelanin* -red/pink -found in pink skin (lips, nipples, genitals) -*turns red when mixed with eumelanin*

What can Exocrine Glands secrete? (3)

*Exocrine Glands* 1. *Mucous* -viscous and slimy -highly glycosylated proteins (makes fluid viscous) 2. *Serous* -watery -proteins not glycosylated 3. *Sebaceous* -lipid products

What is a Flexion Teardrop Fracture? Associated syndrome?

*Flexion Teardrop Fracture* -most severe and most unstable. -posterior displacement into spinal canal. -disruption of ligamentum flavum and spinal canal. (Anterior spinal cord syndrome - quadriplegia)

What causes Functional Scoliosis? What is the worst version of this?

*Functional Scoliosis* -has nothing to do with a problem in the vertebral column -something happening *elsewhere* that is influencing the vertebral column -leg length discrepancy is a common cause

What is a ganglion?

*Ganglion* - a group of functionally-related PNS neuronal cell bodies

What is Gastroschisis?

*Gastroschisis* -defect in the anterior abdominal wall *lateral to the midline* -viscera protrude into the amniotic cavity and are bathed in amniotic fluid

Gray Matter is where in the spinal cord? What direction does it transmit information? White matter is where? What direction does it transmit information?

*Gray Matter* = more central -transmits information laterally to and from spinal nerves *White Matter* = more peripheral -transmits information up and down the spinal cord

What structure is found at the center of each Osteon?

*Haversian (central) Canals*

What stem cells give rise to Osteoclasts?

*Hematopoetic Stem Cells* give rise to Osteoclasts

What are three Basophilic structures that Hematoxylin can stain?

*Hematoxylin* 1. DNA/RNA 2. Ribosomes (rER, nucleolus) 3. Secretory vesicles/granules

What type of cartilage covers the epiphysis of long bones?

*Hyaline Cartilage*

Where is Hyaline Cartilage found? What does Hyaline Cartilage secrete? Can it repair well? What connective tissue surrounds Hyaline Cartilage? Does this cartilage ossify with age?

*Hyaline Cartilage* -found at ends of long bones or within growth plates -secretes *Hyaluronic Acid* -can't repair well due to avascularity -surrounded by *perichondrium* (CT) -yes, ossifies with age

Where is Hyaline cartilage found?

*Hyaline Cartilage* -smooth -found at articular ends of long bones

Bones are made up of 30% Organic and 70% Mineral components. What makes up a majority of the mineral components?

*Hydroxyapatite Crystals* - contain a lot of calcium

How does In Situ Hybridization work? Name an example of this kind of assay?

*In Situ Hybridization* -uses labeled complementary DNA or RNA to dye a specific sequence *Fluorescence In Situ Hybridization* (FISH)

What are the two layers of the Zygopophyseal joint capsule?

*Inner Synovial Layer* -highly vascular and makes synovial fluid (lubricant) *Outer Fibrous Layer* -holds the joint together

What are the two different types of Ossification to produce bone? What are the steps that lead to bone for these? What are examples of bones from both of these?

*Intramembranous Ossification* -Mesenchyme --> bone -skull, part of clavicle *Endochondral Ossification* -Mesenchyme --> *Cartilage* --> Bone -long bones, vertebrae

What are two types of Connective Tissue Proper?

*Loose Connective Tissue Proper* -collagen fibers and cells are loosely packed -abundant ground substance -(looks like fish caught in a fishing net) *Dense Connective Tissue Proper* -abundant collagen fibers -only a little ground substance

How is the Mesoderm formed?

*Mesoderm* is formed by Epiblast cells that invaginate to form a mesoderm layer dorsal to the endoderm

What is Mesothelium? Example?

*Mesothelium* - simple squamous epithelium that acts as a protective layer lining closed body cavities ex: pleura of lungs, peritoneum of abdomen, pericardium of heart

How do you identify Skeletal Muscle with histology?

*Multiple nuclei* that are located *peripherally* -this is indicative in both axes

When Neurulation begins from the Notochord inhibiting BMP signaling, what structure begins to form?

*Neural Groove*

What causes Neuromuscular Scoliosis? What is the worst version of this?

*Neuromuscular Scoliosis* -scoliosis is a frequent complication of neuromuscular disorders -cerebral palsy, Duchenne Muscular Dystrophy

What is the Notochord?

*Notochord*, -a cartilaginous rod that forms ventral to the neural tube

What is an Odontoid View? What does it allow you to see? What is a Fuchs view? What does it allow you to see?

*Odontoid View* -beam directed perpendicular to *open mouth* -allows viewing of odontoid, lateral masses of C1, body of C2 *Fuchs View* -supine, neck hyperextended -beams directed directly below chin -shows tip of dens

What is Omphalocele?

*Omphalocele* -viscera herniate *into proximal part of umbilical cord* -viscera covered in periotoneum and amnion

What is Osteogenesis Imperfecta (Brittle Bone Disease)?

*Osteogenesis Imperfecta (Brittle Bone Disease)* -weakening of bone due to mutations in *collagen*

What are two types of Osteogenesis Imperfecta (Brittle Bone Disease)? Gene mutated? Symptoms?

*Osteogenesis Imperfecta (Brittle Bone Disease)* Type 1: -most common (80%) -autosomal dominant disorder -allele of the *alpha-1-procollagen gene* is missing -results in decreased collagen production, but normal collagen structure -Symptoms: delayed fontanelle closure, bone deformity, fragile bones, short stature, joint laxity, *blue sclera*, and hearing loss Type 2: -point mutation of *COL1A1 gene* -characterized by extreme bone fragility and death in fetus/early infant

What is the functional unit of bone tissue?

*Osteon*

What is Paget's Disease?

*Paget's Disease* -disease caused by over-reactive osteoblasts *following* a period of bone breakdown by osteoclasts. -thickened bone. -misshapen and fragile bones. -mosaic jigsaw puzzle osteon arrangement. Bone fragility results from *haphazard osteon organization*

What is Pectus Excavatum? What is Pectus Carinatum?

*Pectus Excavatum* -an indention of the sternum *Pectus Carinatum* -looks like the bifurcation of lungs (carina)

What do the Pelvic Splanchnic (S2-S4) (so they're parasympathetic) nerves innervate?

*Pelvic Splanchnic Nerves (S2-S4)* -Inferior gut tube -Bladder -Reproductive organs

What are two specific types of Hyperflexion Injuries of the spine?

*Perched Facets* -inferior articular facet is displaced anteriorly -rests on Superior Articular Facet of inferior vertebra Hung Facets

What is the Periodic Acid-Schiff (PAS) Stain used for? What does it look like?

*Periodic Acid-Schiff (PAS) Stain* -stains polysaccharides pinkish purple -glycogen, mucin

In an autonomic circuit, what is the neuron called when it's before the ganglion? After?

*Pre-ganglionic* - before the ganglion *Post-ganglionic* - after the ganglion

What domain of the Axial Skeleton gives rise to the back, posterior neck, and intercostal muscles?

*Primaxial Domain* gives rise to back, posterior neck, and intercostal muscles

Somites have mesenchymal cells that migrate to become the myotome What are the myotome cells that are more medial (close to the neural tube) called? What are the myotome cells that migrate into the Lateral Plate Mesoderm?

*Primaxial* - stayed IN the somite to differentiate, close to the neural tube -(primaxial ~= proximal) *Abaxial* - migrate OUT of the somite to differentiate in the lateral plate mesoderm

What is a Pseudostratified Epithelium? Can there be cilia?

*Pseudostratified Epithelium* -actually a simple columnar epithelium -all cells are reach the basement membrane, but their nuclei are present at different levels -Can be ciliated or non-ciliated

How is Psoriasis characterized?

*Psoriasis* -hyperproliferative disease -faster turnover of skin cells (3-10 vs. 20-30 days) -increased skin thickness because Keratinocyte differentiation is faster than dequamazation

What are Reticular connective tissue Fibers like?

*Reticular Fibers* -thin -*type 3 collagen* -form meshwork, rather than ropes -ex: stroma of organs

What are Splanchnic nerves that are present from T10 - L2?

*Sacral (Lumbar) Splanchnic Nerves*

What are three types of Sacralization? What syndrome is associated with these?

*Sacralization* Type 1 = transverse process extends out (1a = unilateral, 1b = bilateral) Type 2 = synovial joints are formed with the sacrum (2a = unilateral, 2b = bilateral) Type 3 = transverse process fuses with sacrum (3a = unilateral, 3b = bilateral) *Bertolotti Syndrome*

What is a Sacroccoccygeal Teratoma?

*Sacroccoccygeal Teratoma*, -failure of primitive streak to regress fully at the end of week 4, -primitive streak regresses caudally until it's gone

What exactly is Scoliosis?

*Scoliosis* -abnormal curves of the spine in the coronal plane

What are associated structures with the hair follicle?

*Sebaceous Gland* - secretes along shaft of hair follicle *Apocrine Sweat Gland* *Arrector Pili Muscle* - contraction causes hair to stand on end -smooth muscle *Free nerve endings*

What is a Tendon? What is a Ligament? What type of connective tissue makes up these two structures?

*Tendon* - connects bone to muscle *Ligament* - connects bone to bone Dense Connective Tissue Proper (regular, not irregular)

Each Paraxial Mesoderm forms what bilateral columns of mesenchymal tissue on either side of the notochord? What is the end product of this structure?

*Segmental Plate* End product = *Somites* -makes sense because we're developing cranially to caudally, so the segmental plate at the caudal end hasn't become somites yet Shouldn't the arrow be pointing the opposite direction?

What is the Silver Stain used for? What does it look like?

*Silver Stain* -human tissue basement membranes, nucleic acids, reticular fibers (black) -pathogens like bacteria, fungi, specifically *Spirochetes*

What is a Simple Duct? What is a Compound Duct?

*Simple Duct* -unbranched *Compound Duct* -branched

What is Situs Inversus? What are two types?

*Situs Inversus*, -organs being mirror images of normal. 1. *Complete* - all organs mirror image, 2. *Incomplete* - only a SINGLE organ is involved

Both Gastroschisis and Omphalocele are defects in which layer?

*Somatopleure Layer* -aka: parietal lateral plate mesoderm + ectoderm

What is Spina Bifida Occulta? Meningocele? Meningomyelocele?

*Spina Bifida Occulta* -failure of vertebral arch to form -covered dorsally by skin *Spina Bifida Cystica* (two types): 1. *Meningocele* -same as above, but meninges + CSF protrude outward. -forms a cyst. 2. *Meningomyelocele* - meninges and neural tissue, - entire cord protrude

What is Spina Bifida?

*Spina Bifida* -failure of the caudal (posterior) neuropore to close between days 22-28

What is Spondylolysis? What is Spondylolisthesis?

*Spondylolysis* - "spondylos-" = vertebrae "-lysis" = loosening -you can have a defect in the pars interarticularis without symptoms *Spondylolisthesis* - "spondylos-" = vertebrae "-olisthesis" = to slip -Slipping of the vertebrae

What are the only two places in which Stereocilia are found?

*Stereocilia* -male reproductive system (absorption) -inner ear (mechanosensation)

What is a potential space between the meninges? Why does this space not normally exist?

*Subdural Space* - a potential space between dura and arachnoid -This space does not normally exist because the Subarachnoid Space is inflated like a balloon, pushing it *directly up against* the Dura Mater

What is a Swimmers View?

*Swimmers View* -arm abducted 180 degrees -horizontal to axilla

When comparing the Visceral Afferents that are paralleling Visceral Efferent nerves of the Sympathetic and Parasympathetic nervous system, Which reaches conscious-level sensation?

*Sympathetic Visceral Afferent* signals reach conscious-level sensation, while Parasympathetic Visceral Afferent signals do not reach conscious-level sensation

What are Teratomas?

*Teratomas*, -tumor cells, but they're *of germ cell origin*, -ex: teeth, hair, bone, brain, etc.

The GVEs that ascend to the Superior Cervical Ganglion, synapse, then descend onto viscera are called what? What level? Why do these look like Splanchnics?

*Thoracic Cardiac and Pulmonary Nerves* and *Cervical Cardiac Nerves* T1 - T4 These look like Splanchnic nerves because it's leaving the Sympathetic Chain down to organs

What syndrome can a Cervical Rib cause? How does this clinically present? What makes this presentation worse?

*Thoracic Outlet Syndrome* -the brachial plexus and/or subclavian artery are being impinged upon by the cervical rib -Paresthesia, muscle weakness -Lifting the arm exacerbates the problem

What are two types of Osteoperosis? What are their causes?

*Trabecular Bone is highly metabolically active, so it makes sense that places like vertebrae and hips are going to have a lot of resorption of bone* Primary Osteoperosis -age-related bone loss Secodary Osteoperosis -bone loss due to secondary causes -lifestyle, medication, disease

What is Transitional Epithelium useful for? What is the top layer of cells called?

*Transitional Epithelium* -useful for distension -found in the lower urinary tract (bladder, urethra)(makes sense) -top layer of cells of Transitional Epithelium is called *Umbrella Cells*

What is the Trichrome Stain used for? What does it look like?

*Trichrome Stain* -used for connective tissue staining (collagen becomes prominent)

What is a Tubular Duct? What is an Alveolar (Acinar) Duct?

*Tubular Duct* -shaped like a tube *Acinar Duct* -shaped like a flask or grapes

What are Unicellular Glands? What is an example of this? What do they secrete?

*Unicellular Glands* -individual cells that function as glandular tissue *Goblet Cells* -mucus-secreting cell of the GI and respiratory system -mucin doesn't stain well, so it gives the cell a "goblet"-like appearance

What does the Ventral (visceral) Layer of the Lateral Plate Mesoderm differentiate into?

*Ventral (visceral) Layer* -walls of the gut tube -visceral pleura/peritoneum -cardiac muscle -lung/tracheal cartilages -connective tissues

What type of fibers are present in the Ventral Root? Where are the cell bodies for those fibers?

*Ventral Root* -efferent (motor) fibers only -GSE -GVE

What is the venous system of the spine called? What two structures does this system connect? Why is this clinically significant?

*Vertebral Venous Plexus* -provides a vascular link between the Pelvis and Cranium -Metastatic cancers originating in pelvis can travel up spine and brain

What are examples of Visceral Afferent Sensations?

*Visceral Afferent Sensations* -blood gas -blood pressure -cramping -distension -irritants

What division of the Peripheral Nervous System (PNS) are both of the divisions of the Autonomic Nervous System (ANS) present within?

*Visceral Efferent* division of the PNS

What structure connects the vessels of two Osteons together?

*Volkman's Canal*

What is a Wedge Fracture?

*Wedge Fracture* -stable -loss of height on anterior vertebral body -posterior cortex intact

What is the Weigert's (Elastic) Stain used for? What does it look like?

*Weigert's (Elastic) Stain* -stains elastic fibers (black/dark blue) -stains VASCULATURE well

What is Woven Bone? What cell is overactive?

*Woven Bone* is laid down following a fracture -increased *osteoblast* activity produces disogranized bone structure

How do you identify Cardiac Muscle with histology?

*Y-branched* cells with a *central* nucleus that isn't peripherally located -*Intercalated discs* (ID) (allow rapid communication for cooperative contraction of cells)

What are the four zones of the growth plate?

*Zone of Proliferation* -chondrocytes (cartilage cells) undergo division and actively produce *collagen* *Zone of Hypertrophy* -chondrocytes getting larger in size -chondrocytes are still metabolically active *Zone of Calcified Cartilage* -chondrocytes begin to *degenerate* and the ECM calcifies -forms as an initial scaffold for deposition of new bone *Zone of Resportion* -calcified cartilage resorbed and replaced with osteoprogenitor cells (osteoblasts and osteoclasts)

How does nervous tissue look with Histology?

-Large cell body -Prominent nucleus/nucleolus -Supporting (glial) cells surrounding them

Where is Elastic Cartilage found?

-bendy places like External Ear

How do you identify Smooth Muscle with histology?

-often when you section smooth muscle longitudinally, you'll find transversely sectioned smooth muscle next to it

What do Chondrocytes look like on a stain?

-roundish appearance -prominent nucleus -lipid buildup in cytoplasm (slide is hyaline cartilage)

Where is Fibrocartilage found?

-toughest cartilage -found in symphyses and articular disks (IVD)

When gastrulation begins, how do Epiblasts migrate?

1. *Epiblasts* (blue cells) travel down the primitive streak, 2. Epiblasts invade the inside of the embryo -displaces the *hypoblasts* (yellow cells), 3. Epiblasts then become the *Definitive Endoderm*

What are the four main tissue types? What are their main functions?

1. *Epithelium* - protection & secretion 2. *Connective Tissue* - connect tissues 3. *Muscle Tissue* - has contractile properties, responsible for movement 4. *Nervous Tissue* - conducts signals used for communication throughout the body

(continued from flashcard that asked: what are the major components of connective tissue?) What are three common types of cells found in Connective Tissue?

1. *Fibroblasts* 2. *Mast Cells* 3. *Adipocytes*

What are the steps for tissue preparation for staining? (7)

1. *Fixation* - inactivate degradative enzymes (prevent autolysis) -formalin is what is used in the cadaver lab to fix the tissues of the cadaver 2. *Dehydration* - removing water by placing the tissue in increasing concentrations of alcohol solutions, ending with 100% 3. *Clearing* - removing alcohol using organic solvents -called "clearing" because some of the organic solvents also break down some of the pigments in the tissues, making it appear "clear" 4. *Infiltration* - place tissue in melted paraffin until completely infiltrated 5. *Embedding* - allow infiltrated tissue to harden 6. *Trimming and Sectioning* - hardened tissue is trimmed to expose tissue for sectioning using a microtome 7. *Staining* - tissue is exposed to reactive agents that impose contrast to specific features of interest

What are four types of Cell-to-Cell junctions of epithelial cells? (from most apical to most basal)

1. *Tight/Occluding Junctions* 2. *Adherens Junctions* 3. *Desmosomes* 4. *Gap Junctions*

What are the THREE tissues types that Paraxial Mesoderm (somites) differentiate into?

1. Dermatome 2. Myotome 3. Scleratome

How do the muscles of limbs begin to form?

1. Hox genes decide where on the trunk a particular limb will be located 2. Abaxial myoblasts from the trunk migrate into the limb and start to develop into limb muscles

What are three types of Apical Modifications in increasing size order?

1. Microvilli (shortest) 2. Cilia 3. Stereocilia (longest)

Mesenchymal cells have now differentiated into Myoblasts, What is the next step in muscle formation?

1. Myoblasts fuse to form *Myotubes* 2. Myofilaments arise in the myotube cytoplasm along with myofibrils 3. Myoblasts continue to fuse and line up next to myotubes to create *secondary myotubes* 4. After nerve connects to the muscle, it becomes a maturing muscle fiber

Neural Crest cells migrate to form what structures? (11)

1. Sensory ganglia of cranial and spinal nerves 2. Autonomics 3. Schwann cells 4. Meninges 5. Connective tissue/bone of the face and skull (*NCCs develop A LOT for the face and the skull*) 6. Dermis, vascular smooth muscle of face and skull 7. *Odontoblasts* (tooth forming cells) 8. Parafollicular cells of the thyroid gland 9. Chromaffin cells of the adrenal medulla 10. Conotruncal septum in the heart 11. Melanocytes

What are the two ways in which Epithelial tissues are classified?

1. number of cell layers 2. cell shape

What surrounds Zygopophyseal joints?

A capsule

What is located inside the DRG?

A lot of cell bodies

When you have a lumen (cavity or channel), how do you refer to the parts of cells of that epithelium relative to that lumen? Example of structure for each? (mehhhh, not great)

Abluminal - away from the lumen -ex: basement membrane Adluminal - toward the lumen -ex: microvilli or cilia are adluminal

Which Cell-to-Cell junction strengthens Tight/Occluding junctions?

Adherens Junctions

What can mesenchymal stem cells differentiate into?

Adipocyte Chondrocytes..?? Osteoblasts Muscle cells Neurons

What do Adipocytes look like? What do Adipocytes secrete?

Adipocytes secrete hormones

For Caudal Anesthesia, where does the dural sac end? What about in infants? How does lumbarization affect where the dural sac ends?

Adults - dural sac ends at SV2 Infants - dural sac ends at SV3 Lumbarization significantly lowers the dural sac

Inside the Afferent and Efferent divisions of the PNS, what are voluntary and involuntary divisions of each?

Afferent (sensory) Division -*Somatic* - voluntary (conscious sensations) -*Visceral* - involuntary (unconscious or diffuse sensations) Efferent (motor) Division -*Somatic* - voluntary (can control the muscle) -*Visceral* - involuntary (autonomic and can't control)

What structures do all cartilage have? What cells are located within those structures?

All cartilage have lacunae Chrondrocytes are located within those lacunae

Almost all cartilage is avascular. T/F? What is the exception to this?

Almost all cartilage is avascular (true) -recieve nutrients from diffusion through the extensive ECM Except for some types of Fibrocartilage

What are the specific names for the veins in the spinal cord? (4)

Anterior External Venous Plexus (ext. to vertebral canal) Anterior Internal Venous Plexus Posterior Internal Venous Plexus (int. to vertebral canal) Posterior External Venous Plexus

Anterior spinal cord syndrome

Anterior spinal cord syndrome involves: - complete motor paralysis, - loss of temperature and pain perception distal to the lesion. Since posterior columns are spared, light touch, vibration, and proprioceptive input are preserved. (*Anterior Cervical Cord Syndrome* -quadriplegia, loss of pain and temperature -position, vibration, motion preserved)

What is Appositional Cartilage growth? Increases what length?

Appositional Cartilage growth: - increase in the diameter of bones by the addition of bony tissue at the surface of the pre-existing bone. -undifferentiated cells of the chondrogenic perichondrium become chondroblasts. -new chondroblasts deposit cartilage at the periphery. (Perichondrium: Outer Fibrous Layer-fibroblasts and dense CT2. Inner Chondrogenic Layer-contains progenitor cells that become chondroblasts)

What is Appositional bone growth? What are osteoblasts doing? Where? What are osteoclasts doing? Where?

Appositional bone growth -growth in bone *diameter* -osteoblasts deposit on the external surface of the diaphysis -osteoclasts resorb on the internal surface

What Hox knockout would prevent the Autopod from developing? ...prevent Zeugopod from developing?

Autopod Hox knockout = Hox13 Zeugopod Hox knockout = Hox11 So the lower the Hox number, the higher up on the limb the developed structure is

A 34 y/o pregnant female visits her obstetrician who directs her to the hospital for a routine ultrasound, which shows a small mass protruding from the posterior of the head. The radiologist diagnoses encephalocele. The obstetrician tells her that her baby may be fine after some reconstructive surgery. What is the cause of the infant's condition? A. Failure of the cranial neuropore to close before day 20 B. Failure of the cranial neuropore to close before day 25 C. Failure of the caudal neuropore to close before day 20 D. Failure of the caudal neuropore to close before day 25 E. Failure of the caudal neuropore to close before day 28

B. Failure of the cranial neuropore to close before day 25

What are the two main parts to a Basement Membrane?

Basement Membrane is composed of two parts: 1. *Basal Lamina* 2. *Reticular Lamina*

Body Wall vs. Body Cavity

Body Wall - somatic, body wall, limbs -conscious sensation and motor control Body Cavity - visceral, organs -unconscious sensation and motor control

What cells are inside the medullary cavity?

Bone Marrow (yellow bone marrow in adults) -yellow bone marrow contains a lot of adipocytes

What are the following Brachydactyly Syndactyly Polydactyly Ectrodactyly Cleft foot

Brachydactyly - short digits Syndactyly - fused digits Polydactyly - extra digits Ectrodactyly - loss of a digit Cleft foot - ectrodactyly combined with a fusion of the lateral and medial digits

A newborn female presents with gastroschesis (an opening in the anterior abdominal wall that allows viscera to protrude through). A defect concerning which of the following tissues is the primary contributor to the formation of this congenital anomaly? A. Dermatome B. Myotome C. Parietal lateral plate D. Scleratome E. Visceral lateral plate

C. Parietal lateral plate

What does the Parasympathetic Vagus Nerve (CN X) innervate?

CN X innervates Thoracic and 2/3 of abdominal viscera

What are the CT densities of the following? Air Fat Water Soft tissue/muscle Blood Bone/calcium Metal

CT Densities in Hounsfield Units: • Air - Black [-1000 Houndsfield units (HU)] • Fat - Darker grey [-100 HU] • Water - Dark grey [0 HU] • Soft tissue/muscle - Lighter grey [20-80 HU] • Blood - White [60-100 HU] • Bone/calcium - White [100 HU] • Metal - White [1000 HU]

What are the units by which CT density is measured?

CT density is measured in Hounsfield Units

What vertebra does a Tramatic Spondylolisthesis primarily affect? Where on the vertebra is the fracture?

CV2 -pars interarticularis is fractured

What are the two vertebrae that are very succeptible to Pars Interarticularis breakage?

CV2 and LV5

What is the name of the type of cell that produces cartilage?

Cartilage is produced by *Chondrocytes*

What are three types of Cartilage?

Cartilage: 1. Hyaline 2. Elastic 3. Fibrocartilage

Cell bodies are generally present in the CNS. When cell bodies are found in the PNS, how are they arranged?

Cell bodies are arranged into *ganglia* in the PNS

In an epithelial cell, where are two places that cell junctions can be present?

Cell-to-cell junctions Cell to basal lamina junctions

What is unique about the ability of Cilia to move?

Cilia can be *motile* -allows cilia to beat in coordinated waves -ex: uterine tubes

What is the core of Cilia made up of?

Cilia have *microtubule cores*

ID compact and trabecular bone

Compact bone is going to be on the outside of bone, so if we see skeletal muscle inserting onto it, then we know it's probably compact bone

How are the Concentric Lamellae fibers organized?

Concentric Lamellae are made up of collagen -perpendicular fibers with each consecutive layer

What are four types of Scoliosis?

Congenital Neuromuscular Idiopathic Functional

What are three common types of Fibers found in Connective Tissue?

Connective Tissue fiber types: 1. *Collagenous* (top) 2. *Elastic* (left) 3. *Reticular* (right)

On the spectrum of vascularization, how vascularized is connective tissue? What is the exception for this?

Connective Tissue is VERY vascularized Exception: *cartilage*

What are the contraindications for MRI?

Contraindications for MRI: -ferromagnetic metals -pacer

Which parts of the Integumentary System are considered to be the "Cutaneous Region"? Which parts are part of the "Subcutaneous Region"?

Cutaneous Region -Epidermis -Dermis Subcutaneous -Hypodermis

Which layer of the skin contains cutaneous blood and lymph vessels? Why does this make sense?

Cutaneous blood and lymph vessels are found in the Reticular Layer -makes sense because the Epidermis is all epithelial tissue and *epithelium is avascular*

A newborn male presents with DiGeorge syndrome (a *neural crest syndrome*) due to a deletion on chromosome 22. He displays craniofacial defects, heart defects, and his adrenal gland is underdeveloped. Which other cell type may be affected in this patient? A. Astrocytes B. Lower motor neurons C. Sensory neurons of spinal cord D. Sympathetic chain ganglia E. Upper motor neurons

D. Sympathetic chain ganglia -anything autonomic is neural crest

What day does gastrulation begin?

Day 14

What day does gastrulation and neurulation end?

Day 28

What are two types of Dense Connective Tissue Proper?

Dense Connective Tissue Proper types: 1. *Regular Dense Connective Tissue Proper* -collagen fibers arranged in parallel to one another -fibroblasts sandwiched between cells 2. *Irregular Dense Connective Tissue Proper* -haphazardly arranged

What type of nerve dysfunction would you be looking for in a Dermatome? What type of nerve dysfunction would you be looking for in a Peripheral Nerve Map?

Dermatome - looking for spinal nerve damage Peripheral Nerve Map - looking for peripheral nerve damage

Where is Dense Connective Tissue Proper (irregular) found?

Dermis

Which Cell-to-Cell junctions connect adjacent epithelial cells together (spot weld)?

Desmosomes

What is the bone that surrounds the diaphysis of a long bone called? What is the inside of the diaphysis of a long bone called?

Diaphysis -bone around = *compact bone* -inside = *medullary cavity*

What are two types of immunohistochemistry, and how do they work?

Direct - tagged primary antibody directed against the antigen of interest Indirect - tagged secondary antibody directed against the primary antibody

Abaxial myoblasts invade dorsal and ventral parts of the limb buds to innervate the limb muscles with motor neurons. Which part is extensor and which is flexor?

Doral part = extensor Ventral part = flexor

The Lateral Plate Mesoderm splits into two segments. What are those two segments called?

Dorsal (parietal/somatic) Layer Ventral (splanchnic/visceral) Layer

What are the embryological pre-formations of the dorsal horn and the ventral horn?

Dorsal Horn - *Alar Plate* Ventral Horn - *Basal Plate*

When the Spinal Nerve leaves the spinal cord, what is it called when it's immediately leaving the posterior spinal cord? Anterior spinal cord?

Dorsal ROOT - leaves posterior spinal cord Ventral ROOT - leaves anterior spinal cord

What do the Dorsal Ramus innvervate?

Dorsal Rami -primarily innervate *skin* and *intrinsic muscles of back* and *neck* -also zygopophyseal joints (pain and position sense)

Dorsal and Ventral Rami both have what kind of fibers?

Dorsal and Ventral Rami have both sensory (afferent) and motor (efferent) fibers

What are the three types of Meninges that cover the Spinal Cord going in order of superficial to deep?

Dura Mater Arachnoid Mater Pia Mater

Where do you find Elastic Cartilage?

Elastic Cartilage -external ear -eustachian tube -epiglottis of the layrnx

How is Elastic Cartilage distinct from hyaline cartilage?

Elastic Cartilage is distinguished from hyaline cartilage by the presence of elastin in the ECM

Embryonic Epithelial cells: How tightly connected are they? What do they form?

Embryonic Epithelial cells: -epithelial cells, -tightly connected, -CAN'T MIGRATE, -form *tubes* and *sheets*

Embryonic Mesenchymal (stem) cells: How tightly connected are they? What do they form?

Embryonic Mesenchymal (stem) cells: -connective tissue, -loosely connected, -form *matrices* and CAN MIGRATE and act independently, -aka: multipotent cells

Eosin What is the charge of the dye? What charge does it stain? Is Eosin basic or acidophilic? So it stains what kind of structures?

Eosin -negatively charged, so it stains positively charged molecules -ex: amino groups of proteins -Acidic dye, so it stains acidophilic structures (makes sense)

What are five Acidophilic structures that Eosin can stain?

Eosin can stain: 1. ECM - (specifically collagen) 2. Membranes 3. Cytoplasm 4. Cytoskeleton 5. Secretory Granules

What are the two main cells of Gastrulation? Which cell migration initiates Gastrulation?

Epiblasts - migrates to initiate gastrulation, Hypoblasts

Epiphyseal Growth Plate What is cellularly occuring at the epiphysis side of the growth plate? What is occuring at the metaphysis side of the growth plate?

Epiphysis side = *proliferation* of cartilage, giving thicker cartilage Metaphysis side = old cartilage being *replaced by bone*

So there are junctions between epithelial cells called Epithelial Cell Junctions What two things do Epithelial Cell Junctions depend on most?

Epithelial Cell Junctions depend on: 1. Transmembrane proteins 2. Cytoskeletal elements

How are Epithelial tissues vascularized? What is the exception to this?

Epithelial tissues are *avascular* -all of the nutrients are diffusing from the capillaries in the connective tissue up through the basement membrane to get to the epithelial tissues Exception: Endocrine glands are vascularized

Anywhere you have a body surface, internal or external, you can almost guarantee there's going to be some of what kind of tissue covering that surface?

Epithelium -lines the internal and external body surfaces -lines body cavities -forms glands PROTECC and SECCRETE

What is erythema caused by? What causes the redness (erythema)?

Erythema (sunburn) -UV-induced DNA damage that leads to *keratinocyte apoptosis* -Erythema is caused by vasodilation of cutaneous blood vessels and increased presence of lymphocytes in dermis

How do Erythrocytes stain with Histology?

Erythrocytes -stain bright pink to red -sometimes organized into capillaries

What are three methods of secretion by Exocrine Glands?

Exocrine Glands 1. *Merocrine* - -product secreted via membrane-bound vesicles -product exits through duct -most common 2. *Apocrine* -product secreted with a thin layer of cytoplasm and plasma membrane surrounding it 3. *Holocrine* -product accumulates within the cell and cell lyses to release it (apoptosis)

What is an Extension Teardrop Fracture?

Extension Teardrop Fracture -stable -avulsion of anterior inferior corner of vertebral body -looks similar to flex teardrop, but *no subluxation* -vertical height of fragment > horizontal width

What is a very commonly used term to describe the sum of Fibers and Ground Substance?

Extracellular Matrix

Limb outgrowth is initiated in proximal-to-distal direction via what gene?

FGF10

What two + one things do Fibroblasts secrete?

Fibroblasts secrete *Collagen* and *Elastin* Fibroblasts secrete *Ground Substance*

Fibrocatilage is essentially a cross between what type of cartilage and what type of CT?

Fibrocartilage -cross between *hyaline cartilage* and *dense CT*

Fibrocartilage is found where?

Fibrocartilage -found in IVDs, pubic symphysis, and articular discs within synovial joints (e.g., menisci of knee)

How does Fibrocartilage look different from Hyaline Cartilage histologically?

Fibrocartilage contains parallel bundles of Type 1 collagen similar to dense CT

What is the function of Fibrocartilage?

Fibrocartilage functions as a shock-absorber and high tensile strength

What is the ligament that comes off of the Conus Medullaris?

Filum Terminale

How does *gastrulation* begin?

Formation of the *primitive streak* at the *caudal* part of the embryo

Both Pectus Excavatum and Pectus Carinatum are defects in which layer?

Fusion at the midline of the *parietal lateral plate*

Define: GSA GVA GSE GVE

GSA - General Somatic Afferent -sensory information that is carried from a somatic structure GVA - General Visceral Afferent -sensory information that is carried from a visceral structure GSE - General Somatic Efferent -motor information going toward a somatic structure GVE - General Visceral Efferent -motor information that is going toward a visceral structure

What is the difference in the number of peripheral nerves between GSAs, GSEs and GVEs? What does this allow for?

GSA/GSEs are both one neuron chains GVEs are 2, maybe 3 neuron chains -a larger number of neurons allows for modifications onto the signal that's being transmitted -*so our autonomic motor system is more modifiable than our somatic motor system*

Where are GSE cell bodies located in the spinal cord? Where are GVE cell bodies located in the spinal cord?

GSEs = *Ventral horn* of the spinal cord GVEs = *Lateral horn* of the spinal cord

What is the path that GVAs use to get back to the DRG?

GVAs piggy back on a Splanchnic or a parasympathetic nerve like vagus -go to DRG, where pseudopolar neuron body is located

Although the GVEs are present in the Lateral Horn of the spinal cord, which horn do they leave the spinal cord from?

GVEs leave the spinal cord via *Ventral horn*

Which Cell-to-Cell junction simply creates an open system between two cells, allowing free flow of cytoplasm, ions, small molecules, etc.?

Gap Junctions

What class of Transmembrane Proteins do Gap Junctions rely on? What is the function of those proteins?

Gap Junctions -*connexins* -6 connexins make up a "Connexon"

What are two types of Glandular Tissue? How do each of these tissues secrete?

Glandular Tissue 1. *Exocrine* - -secretes a product onto a surface directly or through ducts or tubes 2. *Endocrine* - -secrete a product into connective tissue to enter the bloodstream or directly into bloodstream

What is it called if we use a Silver Stain on neural tissue?

Golgi Technique -stains neurons black

What are Splanchnic nerves that are present at T5 - T10?

Greater, Lesser, and Least Thoracic Splanchnic nerves -(preganglionic

What are three types of Connective Tissue Ground Substance? Example of each

Ground Substance types: 1. *Liquid* -blood plasma, interstitial fluid 2. *Semisolid* -most common -gelatinous material -found in connective tissue proper (dense and loose) 3. *Solid* -bone and cartilage

When using an H&E stain, why is bone matrix pink? When using a Silver stain on bone, what are the small black structures?

H&E - bone is pink because of abundant collagen Silver stain - black structures are osteocytes

What are the components of the bulb of the follicle? (3)

Hair Follicle Bulb: -*Melanocytes* - contribute pigment -*Matrix Cells* - differentiate into keratinocytes to secrete hard keratin -*Dermal Papillae* - loose CT, contains vasculature

What layers of skin do Hair Follicles invaginate?

Hair Follicles invaginate epidermis into dermis and hypodermis

The most anterior paraxial mesoderm forms what tissue that gives rise to the skull and face?

Head Mesoderm

Hematoxylin What is the charge of the dye? What charge does it stain? Is Hematoxylin basic or acidophilic? So it stains what kind of structures?

Hematoxylin -positively charged dye that binds to negatively charged structures -ex: nucleic acids, carboxyl groups of proteins -Basic dye, so it stains basophilic structures (makes sense)

What are the two main dyes used in Histology? What is the main reason they're used so much?

Hematoxylin & Eosin -*very fast* -can also optimize the H&E protocol to fit different tissues types, etc

What are two Cell-to-Cell junctions that are present on the Basal Lamina? What do they do?

Hemidesmosomes Focal Adhesions - both of these function like Desmosomes in spot welding the cell to the basal lamina of the basement membrane

What class of Transmembrane Proteins do both of the basal cell-to-cell junctions Hemidesmosomes and Focal Adhesions rely on? How are they different in what they're linking to the basement membrane?

Hemidesmosomes and Focal Adhesions -both rely on *Integrins* Hemidesmosomes - link *intermediate filaments* Focal Adhesions - link *actin filaments*

How is Holocrine secreted?

Holocrine is secreted when cells fill with sebum and undergo programmed cell death to release it

What do Endocrine Glands secrete? What structure do they secrete from?

Hormones -secrete through basal lamina directly into blood stream

What structure are Osteoclasts found in?

Howship's Lacuna

What gene class determines what position the limb is on the trunk of the body?

Hox genes

What is the embryological structure that gives rise to: Humerus/Femur Radius/Ulna, Tibia/Fibula Carpals/Digits, Tarsals/Digits

Humerus/Femur - *Stylopod* Radius/Ulna, Tibia/Fibula - *Zeugopod* Carpals/Digits, Tarsals/Digits - *Autopod*

What cartilage type comprises much of the fetal skeleton?

Hyaline cartilage

What are two types of calcium molecules present in Hydroxyapatite Crystals?

Hydroxyapatite Crystals = *calcium phosphate* + *calcium hydroxide*

What type of posture does a person with Ankylosing Spondylitis present with?

Hyperkyphosis

What is the Hypodermis composed of?

Hypodermis -loose connective tissue -adipose tissue separated by connective tissue -fascia (primarily collagen)

When does Idiopathic Scoliosis usually manifest?

Idiopathic Scoliosis -usually manifests during a growth spurt associated with adolescence

How does the Notochord persist in adults?

In the Intervertebral Discs as *Nucleus Pulposus*

How does bone initially form in a fetus?

In the first two months of development, we just have a cartilaginous model of the skeleton At 2-3 months, ossification occurs

What is India Ink?

India Ink is a stain that is used to stain a thin slice of *de-cellularized* bone -specimen is dipped in ink and the spaces where osteocytes *WERE* will stain dark blackish-blue

What are the two main components of the Integumentary System?

Integumentary System -consists of an *epithelium* overlying *connective tissue*

What are the three main layers of the Integumentary System? What are these three layers primarily composed of?

Integumentary System: -*Epidermis* - stratified squamous keratinized epithelium -*Dermis* - mostly dense irregular connective tissue -*Hypodermis* - adipose tissue and loose connective tissue

What is Interstitial Cartilage growth? Increases what measurement? Forms what groups?

Interstitial Cartilage growth: increase in the length of bones by the cartilage lengthening and is replacing by bone tissue. -chondrocytes within the cartilage matrix divide to produce new chondrocytes -"isogenous groups" are formed

What is Interstitial bone growth? What does this type of growth require?

Interstitial bone growth -growth in bone *length* -requires a *hyaline cartilage growth plate* between *epiphysis and metaphysis*

How does Cartilage repair itself? What is a way to surgically initiate to induce new chondrocytes to form from mesenchymal bone marrow cells?

It has a very limited repair capacity due to being avascular If it repairs, then it would be *more fibrous* than it was before, so less smooth and lubricated Microfracture Technique

How does a GVA fiber get back to the spinal cord?

It rides the GVE fibers back!! Notice that the body of the pseudounipolar neuron is in the DRG, with one arm reaching into the periphery and one arm reaching into the spinal cord Splachnic nerves have GVA and GVE fibers

What is the fracture called that occurs when the skull crushes the anterior and posterior arch of the Atlas?

Jefferson Fracture

Where does Keratinization begin? Why does this make sense?

Keratinization begins in the *Stratum Basale* -this makes sense because that is where Keratinocytes *originate*

Which cells produce Keratin? What are two types of Kertain? Where are each of these types found?

Keratinocytes -Hard Keratin (nails and hair) -Soft Keratin (*epidermis*)

What is Klippel-Feil Syndrome?

Klippel-Feil Syndrome -process of resegmentation is incomplete in the neck and original scleratomes remain attached -results in fused cervical vertebrae

Why is gray matter gray?

Lack of myelin, and high density in the number of cell bodies

What is the space within bone that contains Osteocytes?

Lacuna

What creates the Water Barrier present in the skin? Why is the Water Barrier clinically important?

Lamellar Bodies released by Stratum Granulosum cells -lipid-rich The water barrier allows for lipid-soluble molecules to be absorbed through the skin, but not water-soluble

How can you tell Mast Cells apart from Fibroblasts?

Mast Cells are much larger Mast cells also have more basophilic secretory granules so that they stain much darker than Fibroblasts

What do Mast Cells look like? What do Mast Cells secrete?

Mast Cells secrete histamines and cytokines

What cells produce pigment? What Integumentary Layer are these cells located? What cells do they primarily communicate with?

Melanocytes -located in Stratum Basale Primarily communicate with Keratinocytes

What is the Melanocyte doing to communicate with the Keratinocytes?

Melanocytes creates specialized organelles called *Melanosomes* -melanosomes travel to the end of the dendrite projections toward the Keratinocytes -Keratinocytes phagocytose the tip of the Melanocyte's dendrite containing the melanosome -Melanin is released and melanin surrounds the nucleus of the Kertatinocyte

What is special about the structure of Melanocytes? What does this allow for?

Melanocytes have *dendrites* Dendrites allow one melanocyte to communicate with 36 kertatinocytes

Mesenchymal Stem Cells give rise to what two types of bone cells?

Mesenchymal Stem Cells - give rise to *Osteoblasts* and *Osteocytes*

What is Endochondral Ossification?

Mesenchyme --> Hyaline Cartilage --> Bone 1. Start with a Hyaline Cartilage model with a *Perichondrium* 2. As a nutrient foramen pierces the Perichondrium (remember, cartilage is usually avascular), a *Periosteal Bone Collar* forms 3. The first bone that gets deposited is called the *Primary Ossification Center* -in long bones, this is the Diaphysis

What is Intramembranous Ossification? What bones does this occur for?

Mesencyme --> Bone -Skull bones

What are Microvilli like according to: Size compared to cell? Actin?

Microvilli are very small compared to the cell Microvilli have an inner core of actin

After an Osteoblasts lays down a matrix, what process occurs after several days? Why the wait, bub?

Mineralization occurs after several days -need several days to allow for collagen cross-linking

What is the mathmatical organization of Motile vs. Non-motile cilia?

Motile - *9x2* organization -9 doublets around periphery Non-motile - *9x0* organization

What is Mucosa?

Mucosa = epithelium + loose CT -lines body cavities -Epithelium has the two basement membrane layers like normal: basal laminae and reticular laminae -The loose CT is called *Lamina Propria*

How does Myogenesis begin?

Myogenesis -begins with elongation of mesenchymal cell as they differentiate into myoblasts

What is Spina Bifida with Myeloschisis?

Neural *Plate* doesn't fold or complete fusion dorsally -open spinal cord exposed

During Neurulation, what cell type breaks away from the Neural Tube to migrate?

Neural Crest cells

How does Resegmentation of the Scleratome occur? What does this allow for?

Neural Tube next to Scleratome next to Myotome 1. Scleratome breaks into two segments -rostral and caudal segments 2. The caudal fuses with the rostral of inferior vertebra This allows for the myotome to form muscles that *cross a joint to move the back*

The Notochord is inducing the ectoderm to form what neural tissue structure?

Neuro-ectoderm (neural plate)

What is the development progression of cells from the lumen to the periphery of the Neural Tube?

Neuroblast --> Bipolar Neuroblast --> Multipolar Neuroblast --> Neurons

What is the layer of the spinal cord that gives rise to the neuroblasts that become neurons? What is the layer of the spinal cord that gives rise to the Gray Matter called?

Neuroblasts = *Ventricular Layer* Gray matter = *Mantle Layer* White Matter = *Marginal Layer*

What are two types of Neural Cells?

Neurons - transmit the electrical signals Neuroglial cells - support neurons

When abaxial myoblasts invade limbs, what do they bring with them?

Neurons for innervation

What is the joint that allows us to nod "yes" (flexion/extension of skull)? What is the joint that allows us shake our head "no" (rotation of skull)?

Nod = Atlanto-Occipital joint Shake head = Atlanto-Axial joint

What is the function of non-motile cilia? Where do you find non-motile cilia?

Non-motile cilia function in chemical sensation -ex: olfactory epithelium

How does the Notochord form?

Notochord formation: 1. Mesenchymal epiblast cells invaginate through the *primitive node*, 2. These cells migrate cranially to form *Prechordal Mesoderm*

What is Nuclear Medicine/PET scan?

Nuclear Medicine / Positron Emission Tomography (PET) -ionizing radiation -radio-isotopes attached to molecules targeting specific organs or metabolic processes -evaluates function/physiology

What are the tiny holes present in bones called?

Nutrient Foramen - arteries, nerves and veins can go through here

How does the IVD receive nutrition?

Nutrients diffuse from the vascularized *Vertebral End Plates* of the vertebral body

What are the two layers of the Dermis?

Papillary Layer Reticular Layer

What are the three cell types of bone?

Osteoblasts - matrix-forming cells Osteocytes - Osteoclasts -

Where are Osteoblasts found?

Osteoblasts are found on bone surfaces (between peritoneum and bone)

What do OOOs look like on histology?

Osteoclasts are large cells that are *multinucleated*

What is the job of Osteoclasts? Where are they found?

Osteoclasts mediate bone resorption through the secretion of *proteases* and *hydrogen ions* -found on internal and external bone surfaces (between peritoneum and bone)

What is the order of size of Osteoblasts, Osteocytes, and Osteoclasts?

Osteocytes < Osteoblasts < Osteoclasts

What cells are trapped within the concentratic lamellae?

Osteocytes are trapped within the matrix

What structure does the Osteocyte give off that helps it communicate with other Osteocytes?

Osteocytes give off *Canaliculi* to communicate with other Osteocytes

What is the job of Osteocytes? Where are they found?

Osteocytes maintain bone homeostasis to help regulate modeling -found within the bone matrix -osteocytes are just osteoblasts that got *trapped* in the matrix

What is the bone on the outside of the vertebrae called? What is the bone on the inside of the vertebrae called?

Outside = Cortical (compact) bone Inside = Trabecular (cancellous) bone

What is the Papillary Layer of the Dermis composed of? What cells are found here?

Papillary Layer -composed of *Loose Connective Tissue* -*Meissner's Corpuscles* fine, discriminative touch and vibration

What type of information is carried by Sympathetic GVAs vs. Parasympathetic GVAs?

Parasympathetic - innocuous information -ex: chemoception Sympathetics - nociception -ex: referred pain

Where in the body is the Parasympathetic System localized? Where is the Sympathetic System localized? What are the spinal levels for the Sympathetic?

Parasympathetic = *Craniosacral* Sympathetic = *Thoracolumbar* (T1-L2/L3)

Next to the Neural Tube, what are the two main types of Mesoderm? Which of these types of mesoderm compose Somites?

Paraxial mesoderm - form somites Lateral Plate mesoderm

What kind of fractures are present in people with Osteoperosis? What type of posture do these fractures ultimately lead to?

Patients with Osteoperosis have a lot of *Compression Fractures* -these ultimately lead to kyphosis

What are the two layers of Perichondrium? What cells are in each layer?

Perichondrium 1. *Outer Fibrous Layer* -fibroblasts and dense CT 2. *Inner Chondrogenic Layer* -contains progenitor cells that become chondroblasts

On the outside of the bone of long bones, what is that layer called?

Periosteum

What type of connective tissue is Periosteum?

Periosteum = Dense Irregular Connective Tissue

What are the two layers of Periosteum? What cells are found in each of these layers?

Periosteum layers: -*Outer Fibrous Layer* - fibroblasts and dense CT -*Inner Cellular Layer* (Cambium) - contains progenitor cells that become *Osteoblasts*

Through what structure does a pre-ganglionic sympathetic neuron enter the sympathetic chain? Through what structure does it exit the sympathetic chain?

Pre-ganglionic sympathetic neuron enters through *White Ramus* Post-ganglionic sympathetic neuron exits through *Gray Ramus*

What are two types of primary osteoperosis?

Primary Osteoperosis -Type 1 - Post-Menopausal women -Type II - Elderly

What muscles are Primaxial muscles? What muscles are Abaxial muscles?

Primaxial Muscles - *intrinsic back* and *intercostal muscles* Abaxial Muscles - *body wall* and *limb muscles* -imagine your arms having abs with axes tattooed on them

What structures are responsible for innervating Primaxial Muscles? What structures are responsible for innervating Abaxial Muscles?

Primaxial Muscles are innervated by DORSAL RAMI Abaxial Muscles are innervated by VENTRAL RAMI

Why is Gray Matter gray?

Relatively more cell bodies found in the Gray Matter -It's much more dense However, there are more *myelinated axons* in the White Matter

What is the Reticular Layer of the Dermis composed of?

Reticular Layer -dense irregular connective tissue proper -elastic fibers for stretch and recoil -much thicker than the papillary layer

What is the most serious consequence of Rheumatoid Arthritis (RA) in the spine?

Rheumatoid Arthritis of the Median Atlantoaxial Joint -joint between dens and anterior arch of Atlas Immune cells degenerate the ligaments, giving abnormal and dangerous mobility -can compress vertebral arteries or spinal cord

Ribs contact vertebrae in a particular fashion. Which vertebra and what location on that vertebra does rib 7 connect to?

Rib 7 connects with vertebra 7 at the superior border of the vertebra Rib 7 also connects with vertebra 6 at the inferior border

What is it called when a Lumbar Vertebra (LV5) fuses with the sacrum? What is it called when a Sacral Vertebra (S1) doesn't fuse?

Sacralization = LV5 fuses with sacrum Lumbarization = S1 does not fuse with sacrum

How does Acne Vulgaris occur?

Sebum production by sebaceous glands increases during puberty -retention of sebum -some bacteria like to eat the oily secretions -inflammatory response to bacteria

What are the stages of progression of Segmental Plate to Somites?

Segmental plate --> Somitomeres --> Somite

For limb innervation, How are sensory neurons distributed? How are motor neurons distributed?

Sensory = *radial* distribution Motor = *longitudinal* distribution

Where do Sensory Neurons form? Where do Motor Neurons form?

Sensory Neurons form in the *DRG* -grow toward spinal cord -grow out to periphery Motor Neurons forms in the *Ventral Horn*

If an Epithelium is only a single cell layer, what is it called? What if there are more cell layers?

Single cell layer = Simple Epithelium, connected to bassment membrane, Multiple Layers = Stratified Epithelium

What is Sirenomelia (caudal dysgenesis)? What is the cause?

Sirenomelia (caudal dysgenesis), -lower limb fusion, -renal agenesis, -imperforate anus, Cause: inadequate mesoderm production in caudal portion of embryo

What is the Somatopleure? What is the Splanchnopleure?

Somatopleure = dorsal (parietal) lateral plate + surface ectoderm Splanchnopleure = ventral (visceral) lateral plate + endoderm

What causes Spina Bifida?

Spina Bifida -Neural *Tube* doesn't fully close and scleratome mesenchyme *can't migrate dorsal to the neural tube* to form the neural arch Or -Neural *Plate* fails to fold properly

How are spinal nerves typically named? What is the exception to this?

Spinal nerves are typically named for the vertebra that is above them Exception: There are 7 cervical vertebrae with 8 spinal nerves for them -cervical spinal nerves actually go over the top of the vertebrae that they're named for

What does "Splanch-" mean?

Splanch means "viscera"

Where is Reticular Connective Tissue found? stain used?

Spleen and lymphoid organs, difficult to see in H&E - silver stain used

What are the three main Epithelium cell shapes?

Squamous cells Cuboidal cells Columnar cells

What are three types of epithelial cells?

Squamous, Cuboidal, Columnar

As the Keratinocytes mature and become pushed up into the Stratum Granulosum, how does the name of the cell change?

Stratum Granulosum = *Granular Cell* Stratum Spinosum = *Spinous Cell* Stratum Basale = *Basal Cell*

What is the core of Stereocilia made up of?

Stereocilia have a creamy nougat actin core, like microvilli

What tissue layer gives rise to the Sternum? What tissue gives rise to the Costal Cartilages? What tissue gives rise to ribs?

Sternum = *Parietal Lateral Plate Mesoderm* Costal Cartilages = scleratome that *migrates across the lateral somitic frontier* to enter the parietal lateral plate Ribs = *scleratome* that remains within the somite

What is the Stratum Basale/Stratum Germinativum composed of? What cells are found here?

Stratum Basale/Stratum Germinativum -*stem cells* of the epidermis -*melanocytes* -*keratinocytes* originate here -rests on a basement membrane

What is the Stratum Corneum composed of?

Stratum Corneum -comprised of dead, flattened cells with no nucleus (coneocytes) -*abundant keratin content*

What is the Stratum Granulosum composed of? (2)

Stratum Granulosum -intensely staining granules due to the *Keratohyaline Granules* (binds keratin filaments together, very dye soaky) -forms *Lamellar Bodies* (waterproof barrier)

Where do you mainly find Langerhans Cells in the skin?

Stratum Spinosum

What is the Stratum Spinosum composed of?

Stratum Spinosum -*Langerhans Cells* found here (APC)

Sympathetic pre-/post-ganglionic neurons Parasympathetic pre-/post-ganglionic neurons What are their relative lengths?

Sympathetic pre-/post-ganglionic neurons = *short, long* Parasympathetic pre-/post-ganglionic neurons = *long, short*

For the sympathetic nervous system, what NT is secreted at the preganglionic synapse? For the parasympathetic nervous system, what is secreted at both pre-and-post-ganglionic synapses? For the sympathetic nervous system, what NT is secreted at the postganglionic synapse?

Sympathetic: -pre-ganglionic = ACh -post-ganglionic = norepinephrine Parasympathetic: -pre-ganglionic = ACh -post-ganglionic = ACh

The only vertebra that has a full and an inferior demi costal facet is...

TV1

How does the Papillary Layer contribute to Fingerprints?

The *Dermal Papillae* of the Papillary Layer of the Dermis form ridges that increase surface area for a connection between the dermis and epidermis -these ridges form fingerprints

How is the Ectoderm formed?

The *Ectoderm* is formed by the remaining epiblast cells from gastrulation

What structures does the neuro-ectoderm give rise to? What is this process called?

The *Neuro-Ectoderm* gives rise to CNS, PNS, and neural crest cells, This occurs through a process called *Neurulation*

What is the Primitive Node?

The *Primitive Node* is a group of cells that forms at the cranial end of the primitive streak, -the *organizer* of the embryo, telling cells where to go, what to do, -helps establish the longitudinal axis (directionality) of the embryo by organizing tissues that form the notochord

What is the Primitive Streak?

The *Primitive Streak* is the groove through which epiblasts undergo EMT and migrate, -once migrated through this groove, they differentiate into three germ tissues

How is the Arrector Pili Muscle unique in its innervation?

The Arrector Pili Muscles are the only muscle of the *body wall* that receives *autonomic innervation*

Why is the Notochord staying close to the Ectoderm (blue cells)?

The Notochord is *inducing* the structure of the ectoderm to form *neural tissue*

What are the signals that the notochord is expressing to induce the ectoderm into the neural plate? If the notochord is not present to induce the ectoderm, what occurs?

The Notochord is expressing *NOGGIN* and *CHORDIN*, -NOGGIN and CHORDIN *inhibit BMP signaling* in the ectoderm, Without BMP signaling, ectoderm differentiates to neuro-ectoderm, -if the notochord is NOT PRESENT, ectoderm differentiates into *Epidermis*

Between Stratum Granulosum and Stratum Corneum, what occurs to the Granular Cell?

The cell dies -breakdown of nucleus and other organelles -*thicker plasma membrane* -acidification

When you have a stratified epithelium, the cell shape of the Epithelial layer is determined by what?

The cell shape at the *apical surface*

What does the density of tissue on a radiograph depend on?

The density of tissue on a radiograph depends on the *amount of absorption* of an xray beam

What *IS* gastrulation?

The formation of the three germ layers: endo, meso, and ectoderm from the embryonic disk

If an IVD herniates in the cervical or lumbar region, which spinal nerve will be preferentially affected?

The inferior spinal nerve Ex: -C6/C7 IVD will affect C7 spinal nerve -L4/L5 IVD will affect L5 spinal nerve

What increases the rate of melanogenesis?

The pituitary produces melanocyte-stimulating hormone (MSH) -MSH levels are similar across varying skin tones Lighter skin = melanocytes are less sensitive to MSH UV-induced damage = increased melanogenesis, resulting in tanning and freckling

What is the process by which Somites are formed? What are Somites?

The process by which Somites are formed is called *Segmentation* *Somites* are segments of the body

If there are lipid droplets, like with the smooth ER, how does the stain present?

There is no stain

How does Referred Pain of the heart work with GVAs vs. GSAs?

Thoracic and Cervical cardiac nerves (sympathetic) carry localized visceral pain This signal overlaps with spinal cord segments with somatic afferents going to the same level

What two Transmembrane Proteins do Tight/Occluding Junctions rely on? What is the function of those proteins?

Tight/Occluding Junction proteins: -*Occludin* - -*Claudin* - both of these link the *actin filaments* of adjacent cells at the lateral domain

Which Cell-to-Cell junctions span the entire periphery of a cell?

Tight/Occluding junctions Adherens junctions

How are the Lamellar Sheets different in Trabecular Bone?

Trabecular Bone -very few *Central Canals* or *Volkman's Canal*

What type of bone is located at the Epiphysis and Metaphysis? What special structure is located in the Epiphysis of adults?

Trabecular bone, AKA: Spongy or Cancellous Bone, *Epiphyseal line* - growth plate

Regardless of shape, all bones have the same composition. T/F?

True

What does the macroscopic structure of Flat Bones look like?

Two layers of compact bone Trabecular bone layer between the compact bone Periosteum outside the trabecular bone

What are two main types of Neuron? What information do they typically carry?

Two main types of neuron: 1. Multipolar -efferent (motor) 2. Pseudounipolar -afferent (sensory) -has one process reaching into the periphery and one axon reaching toward the CNS

Of the Organic components that make up 30% of bone, What makes up a majority of the matrix?

Type 1 Collagen

What is making up the cross-linking in Type 1 Collagen?

Type 1 Collagen -Collagen Fibrils are composed of aligned *Tropocollagen* -Cross-links form between Tropocollagen molecules and give collagen strength and flexibiltiy

How is Type 1 Collagen characterized?

Type 1 Collagen - defined by cross-linking

What are the three types of Cartilage? How are each of them distinguished?

Types of Cartilage 1. Hyaline - mostly Type 2 collagen, small bundles 2. Elastic - elastic fibers 3. Fibrocartilage - Type 1 and 2 collagen Distinguished by which *fibers* are present

What are the two imaging types that don't use ionizing radiation?

Ultrasound and MRI

During fetal development, What direction does the upper limb rotate? What direction does the lower limb rotate?

Upper limb rotates *laterally* Lower limb rotates *medially*

The vertebral vein enters through which transverse foramen first? Which transverse foramen does the vertebral artery enter through first?

Vertebral Vein enters through *CV7* first Vertebral Artery enters through *CV6* first

How is the spinal cord and vertebrae perfused?

Vertebral arteries give off -ONE Anterior Spinal Artery -TWO Posterior Spinal Arteries

What vitamin is necessary for Type 1 Collagen to form cross-links?

Vitamin C

Where is Elastic Connective Tissue found?

Walls of large blood vessels, so they can spring back

How does our skin contribute to Vitamin D synthesis?

When our skin is hit with UV-B rays, the skin converts 7-dehydrocholesterol to *cholecalciferol* (vitamin D3)

What is the difference in function between White and Brown Adipose connective tissue? What makes it brown?

White Adipose - long-term energy storage, hormone secretion Brown Adipose - thermogenesis (babies) -more mitochondria = more brown

What levels of the vertebral column are White Rami present? What levels are Gray Rami?

White Rami are only present between T1-L2 (Sympathetic = Thoracolumbar T1-L2/L3) Gray Rami are present throughout entire spinal cord

What type of waves are used in Ultrasound? X-ray? Nuclear medicine? MRI?

X-ray - *electromagnetic radiation* Ultrasound - *sound waves* Nuclear medicine - *gamma waves* MRI - *radiofrequency waves*

Does Trabecular Bone have a Lamellar Organization like compact bone? Where are osteocytes trapped in Trabecular bone?

Yes Osteocytes are trapped in *Lacuna* between the Lamellar Sheets

When looking at a nerve, is there generally motor information (efferent) going toward muscle AND sensory information (afferent) going toward the spine? Why does this make sense?

Yes, generally efferent and afferent information are *paralleling* within the same nerve -this makes sense because you would need to lay a whole new road if they were not paralleling -would take up a lotta energy

Can a GVE, once it's synapsed in the sympathetic chain, go through the gray ramus to travel into the Dorsal Ramus OR Ventral Ramus?

Yes, it can go into either ramus For example, GVEs would go to your dorsal ramus to innervate back sweat glands

Does the Scleratome give rise to all of the vertebrae and the ribs?

Yeth.

Which zones histologically are shrunk by Achondroplasia?

Zone of Proliferation-chondrocytes (cartilage cells) undergo division and actively produce collagen. Zone of Hypertrophy-chondrocytes getting larger in size-chondrocytes are still metabolically active

What type of joint are the Zygopophyseal Joints? What type of joints are the IVDs?

Zygopophyseal joints = *Synovial Joints* Intervertebral Disks = *Symphysis Joint*

What makes up the gel-like ground substance present in cartilage? (3)

glycosaminoglycans (GAGs), proteoglycans, multiadhesive glycoproteins

Which types of cartilage have a Perichondrium?

hyaline and elastic

Two types of bones: - both names, - 3 other names

two types: - trabecular bone (also called cancellous or spongy bone), - compact bone (also called dense or cortical bone)

How does bone grow in girth & length after it is initially laid down? (bone growth)

we answer this a bit later

What level does the Conus Medullaris exist?

~L1 - L2