Flashcards in Anatomy - All Exams Deck (274):
What is the axial skeleton?
- vertebral column
- rib cage and sternum
- 12 ribs, all but two attached to sternum via hyaline cartilage
What is the appendicular skeleton?
Bones of limbs attached to trunk by girdle.
Arms - clavicle and scapula
Legs - hip bone
What is the medical term for a depression?
What is the medical term for a groove?
What is a spine?
Thorn-like, or ridge dividing a surface into 2 large parts
What is a tubercle/Tuberosity?
Slight swelling or blunt projection
What is a crest?
What is the medical term for a projection (not specifically blunt or ridge-like)?
What is the medical term for a hole?
What are the 3 cardinal planes?
1. Sagittal (verticle) = parallel to sagittal suture of skull. Divides body into right and left.
a) midsagittal (exactly middle)
b) parasagittal (not exact middle)
2. Coronal Plane (verticle) = parallel to coronal suture.
Divides body into front and back.
3. Transverse - horizontal plan
What are the three axis of the body?
1. Longitudinal Axis = head to tail.
Intersection of coronal and sagittal planes.
2. Sagittal Axis = back to front.
Intersection of sagittal and transverse planes.
3. Transverse Axis = Side to Side
Intersection of coronal and transverse planes.
What colours are Haematoxylin and Eosin?
H = basophilic, blue
E = eosinophilic, pink
What processes are involved in preparing slides?
1. Collection of Tissue. Freshness is important or decomposition/autolysis.
2. Fixation - reduces risk of decomposition or autolysis. Tissue treated, usually with formalin. Also makes tissue firm.
3. Dehydration - increasing strengths of ethyl alcohol. Shrinkage.
4. Replacing Alcohol by paraffin solvent, usually toluene. Removes natural fat.
5. Paraffin infiltration
6. Embedding - solidified rapidly in plastic mould = blocks of paraffin
7. Microtomy - cut block. Tears, scratches.
8. Spreading and drying. Wrinkles or folds.
9. Staining - H&E
What are the four types of tissue?
What are some of the main functions of epithelium?
- Barrier. Compactly arranged cells on basement membrane (non-epithelium).
- Active transport (i.e. absorption)
- Simple diffusion
- Replacement of lost cells
Which junctions adhere cells together?
Adhering Junctions. Quite literally just stuck together.
Which junctions seal off intercellular space?
Kind of wavy looking
Which junctions allow communication between cells?
Gap junctions. Like a tube form one to another.
What is a desmosome?
A cell structure specialized for cell-to-cell adhesion. A type of junctional complex, they are localized spot-like adhesions randomly arranged on the lateral sides of plasma membranes.
What is the term given for a single layer of cells?
simple, ie vs stratified/compound
What are the different types of epithelial cell shapes?
1. squamous (squashed nuclei)
They can be simple of squamous, but columnar can be pseudostratified.
How are ducts formed and what are their parts?
They are a type of epithelial specialization, where cells form canalization (hollow tube).
Part of the tube specializes to become 'secretory' (bottom part).
Secretions are carried to the surface by a 'duct' (top part).
What is the characteristic of endocrine glands?
The duct part disappears.
What is a compound gland?
Duct/secretory portion can both be lobed.
Lobe = group of lobules surrounded by connective tissue.
What are the main function of connective tissue?
- Connects and binds
- nutritional support
- mechanical strength support
- transmits and resists force
What are the main components of matrix?
1. Fibers (mostly proteins).
c) Reticular Fibers
2. Ground Substance.
What are the main features of collagen?
- thicker bundles, generally wavy
- resists stretching when straight
- many biochemical types
- tendons are predominantly collagen, and their resistance makes them able to transfer force.
What are the main features of elastic?
- Fibers or sheets (laminae)
- if fibers, then thin, straight, branches.
What are the main features of Reticular Fibers?
- actually a type of collagen
- invisible with H&E
- very thin, network
- support in highly cellular tissues
What are the main features of Ground substance?
- Protein-carbohydrate complexes
- Difficult to see in H&E, and is water soluble
- Variable amount in different types of connective tissue.
- If there are loosely arranged fibers, there is more ground state than if there are tightly packed fibers.
What are the active and inactive principle cell types for fribrous tissue, cartilage and bone?
- fibrous tissue: fibroblast/fibrocyte
- cartilage: chondroblast/chondrocyte
- Bone: octeoblast/osteocyte
How are fibers arranged?
2. Dense - sheets, strips, chords. Can be classes as irregular or regular. Regular are laid down in response to forces by irregular usually indicates forces in different directions.
What are the main properties of loose CT?
- allows stretch until straightened, then resists force
- elastic fibers ensure restoration
- Some movement between connected parts
- Acts as a medium for nerves and blood vessels
- Ground substance allows passage of nutrients, waste, oxygen etc.
- Defense related cells reside in loose CT
- Often extremely loose which allows considerable movement
What are the functions of mast cells in loose CT?
- Granules with vasodilators, released if tissue is injured.
- Blood vessels dilate to increase blood supply
- Increase permeability of basal wall so there is extra fluid in tissue
- Increased blood supply means redness and warmth, and the increased fluid leads to swelling.
What are types of dense CT?
- Deep fascia – though ct sheets which act as envelopes for muscles etc
- Tendons – strong chords for transmitting muscle force to bones.
- Dermis (part of skin)
What is adipose tissue?
- usually modified loose ct.
- Some cells (adipocytes) accumulate fat
- Groups of such fat laden cells form ‘lobules’ (separated by fibrous tissue partitions)
- Adipocyte formation – coalescing fatty droplets
What are the distinguishing features of cardiac muscle?
- Single, central nucleus
- short cells
- fibers branch and are interconnected by intercalated discs.
What are the distinguishing features of smooth muscle?
- Single, central nucleus
- NOT striated
- small, elongated, spindle shaped cells
- nerve regulated (i.e. speed) but also auto-rythmic
What are the distinguishing features of skeletal muscle?
- Many (peripheral) nuclei
What are the differences between axons and dendrites?
Axons transmit info.
Dendrites receive info.
Dendrites are usually short
and close to body, while axons are long.
What is the resting membrane potential or a neuron?
What characteristic makes neuron processes conduct nerve impulses faster?
What cells form myelin sheaths?
- Schwann cells in PNS
- Oligodendroglia in CNS
What are the gaps in myelin sheaths?
Nodes of ranvier
What are glial cells (neuroglia)?
Glial cells, sometimes called neuroglia or simply glia, are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems.
What is the input and output signals of the nervous system?
- Input = sensory = afferent
- Output = motor = effertent
What is the break down of nerves?
- 12 cranial nerves
PNS: 31 pairs
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
What is grey matter?
Nuclei - mass of neuronal bodies
What are the main parts of the brainstem?
- Cerebrum (top brain)
- Medulla oblongata
- Cerebellum (mini brain)
What is the outer layer of the cerebrum?
The cortex = grey matter
What are the two physical features of the cortex?
- sulci (grooves)
- gyri (folds)
What is the outer layer of the cerebellum?
Cerebral Cortex = white matter
What is the physical feature of the cerebral cortex?
Folio = parallel fine folds
What are the components of the brain stem?
- Medulla Oblongata
What are the components of the hind brain?
- Medulla Oblongata
How many cranial nerves does the brainstem have?
How is grey/white matter of spinal chord arranged?
Grey on inside and white on outside
What are the main features of the spinal chord/nerves?
- Motor nerves emerge from anterior (ventral root).
- Sensory nerves emerge from posterior (‘dorsal’ root)
- The dorsal root has a ganglion due to neuron bodies
- with the Autonomic NS, the ganglion is close to the chord
- grey matter has two horns on either side, and an intermediate or 'lateral' horn in the thoracic part
How are spinal/cranial nerves names?
Spinal = first letter of region plus number
Cranial = roman numerals
What is the different between ganglion and a nucleus?
ganglion is outside the CNS but neuclei are inside the CNS. They are both neuron bodies.
What are sensory nuclei?
nuclei that receive sensory info and are in the CNS.
Sensory nerve fibers have their bodies in ganglion. The axons enter the CNS and hand over this info to the next neurons. . These neuron bodies form the nucleus of a sensory nerve.
What do axons form together?
What are tracts in the nervous system?
Bundle of functionally similar axons within the CNS. They are ‘ascending’ or ‘descending’ based on direction of information flow. They start in neuron bodies and terminate were the axons end, usually synapsing with other neurons. Tracts may cross to the opposite side. Each time you reach a ganglion/nucleus, you start a new tract
What are the physical features of the ANS?
- controls viscera
- motor and sensory info
- do get higher control from various parts and centres in the brain (notably – hypothalamus).
- Both SNS and PNS have two neurons, ganglion, preganglionic fiber (finely myelinated) and postganglionic fiber (non-myelinated)
What are the physical features of the PNS? (Para)
- ganglia closer to organs
- craniosacral outflow
What are the physical features of the SNS (Sympathetic)?
- preganglionic fibers have neuron bodies attached to thoracic and lumbar spinal cord – thoracolumbar outflow.
- Ganglia near vertebral column
- Abdominal organs actually have ganglia near the organs (they are the exceptions)
- Head and neck – three neck ganglia
- Pelvic organs – the lumbar segments actually have sacral ganglia.
What sensations occur with visceral afferents?
NEVER TRAVELS WITH SNS, ONLY PNS
What are bundles of collagen indicative of?
Dense connective tissue - very pink.
What is keratin?
Dead epithelial cells characterized by lack of nucleus on surface.
Naming eg: Keratinised, stratified, squamous epithelium.
What are nerves stained with and what do they look like?
White circles with black perimeter. We only see the myelin sheath stained black.
What would epithelium without much keratin look like?
Red. I.e. inside of lip - blood vessels near epithelium.
What is responsible for cartilage's ability to resist compression?
Ground substance. Contains glycosaminoglycans?
What causes lacunae?
During processing, cells shrink more than the surrounding matrix.
What are the cavities around cells in lacunae called and what colour is it?
Territorial matrix - bluish if fresh.
What are the 3 main types of cartilage?
1. Hyaline cartilage
2. White fibrocartilage
3. Elastic Fibrocartilage
What does hyaline cartilage look like?
Glassy pink, fibbers not visible (but they are there). Avascular
What is the fibrous membrane covering hyaline cartilage and what is its purpose?
- carries blood vessels
- consists of outer fibrous layer and inner chrondrogenic layer
What is the principle cell in hyaline cartilage and how is it formed?
Chondroblasts. They are from the condrogenic cells in the deeper part of the perichondrium.
They grow by apposition AND interstitial growth.
They produce matrix
What is apposition in cartilage?
Chondroblasts deposit collagen/matrix on surface of pre-existing cartilage.
Causes an increase in width.
What is interstitial growth in cartilage?
CHRONDROCYTES divide and secrete matrix from within their lacunae.
Causes an increase in length.
What is a sign of interstitial growth?
Isogenous groups = cell nests
Cells are dividing, therefore interstitial growth
Where is white fibrocartilage?
- between vertebrae
- within joints
- in tendons (ligaments)
What does white fibrocartilage look like?
Pink bundles of collagen, not glassy.
There are dense collagen fibres oriented in the direction of functional stresses.
Where is hyaline cartilage found?
Where is Elastic Fibrocartilage found?
- external ear
What is the visual difference between dense connective tissue and fibrocartilage?
Both look similar due to bundles of collagen.
BUT in dense CT we would see flat nuclei as they are squashed by collagen. In cartilage, they are in lacunae and are therefore round.
What is the difference between elastic cartilage and hyaline cartilage?
With elastic, you can actually see the elastic fibres. Otherwise it is similar to hyaline.
What gives bone a mineralised matrix?
Microcrystals = calcium compound deposited along collagen fibbers at regular intervals.
What is the principle cell of bone?
Osteoblasts - produces all components of matrix.
Where are osteocytes?
What are the cells that break up bone?
What is a lamelar structure?
- layers of collagen
- parallel fibers in each layer
What allows resistance in different planes in bone?
many lamella packed together with fivers in different directions
What is an osteon?
Tubular lamellae arranged around blood vessels. Max 6-8 layers, but usually 3/4.
What is the canal in an osteon and what was does it run?
Which canals run transversely across bone?
Volkmann's Canals (not in an osteon).
What are the fine communications between lacunae?
They are the cracks that lead to the black hole (the lacuna with the osteocyte in it)
What is the periosteum and endosteum?
Periosteum: a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints.
Endosteum = lines the inner surface of all bone
What are the names of the outer portion, inner portion and hollow in bone?
- Outer shell = Cortical (Compact) bone
- Inner = Cancellous (spongy) bone
- Hollow = medullary cavity (contains bone marrow)
What are the three types of lamella?
- circumferential lamellae (outer and inner)
- interstitial lamellae (remnants of old osteons)
- concentric lamellae (around osteons). Can just call it osteons.
How do the flat bones in the skull form?
Osteoblasts develop from mesodermal cells. (NOT CARTILAGE)
Process begins at centreS of ossification. Fibrous CT also develops (periosteum between bones).
Then there is reduction in fibrous tissue and interlocking of bones.
What are the soft areas in a baby's skull?
How does bone form from cartilage?
Forms in hyaline cartilage (which are mesodermal masses).
One primary centre of ossification, which spreads. After birth, there are secondary entries.
As it grows, parts of the cartilage die and are replaced by bone.
What is the shaft of the bone?
What is the epiphysis?
End of a long bone, any part formed by secondary centres.
Long bones often have compound epiphyses, made of more than one secondary centre.
What is the junctional region between epiphysis and diaphysis?
It contains the growth plate where bone grows during childhood
What is the growth plate?
- Epiphyseal plate in children
- Epiphyseal line in adults (eventually disappears)
What is the fusion/union of adjacent bones?
Synostosis = epiphyseal fusion
What is the site of fertilisation?
Ampulla - in uterine tube
What is the top of the Uterus called and what is the middle?
Top = 'Fundus' (opposite the cervix)
Middle = 'Body'
What is an Oocyte and what are its main components?
A cell in an ovary which may undergo meiotic division to form an ovum.
Zona Pellucida - non cellular coat just outside membrane
Corona Radiata - Layer of supporting cells outside zone pellucid
What lines the uterus and what are its components?
- epithelium (columnar)
- thick layer of CT
This sheds if not used
What is the product of a fertilised ovum?
What is a blastocyst and what are its components?
Blastocyst is when the fertilised product has formed a cavity.
- Inner Cell Mass (which will become embryo)
- Trophoblast (will become placenta)
What happens during implantation of an embryo?
- Zona pellucida disappears
- Trophoblast burrows into endometrium
NOTE - now have a bilaminar embryo
What are the components of a bilaminar embryo?
- Epiblast (top)
- primitive streak
- amniotic cavity
- yolk sac
What is the primitive streak?
In a bilaminar embryo, it is the heaped up epiblast cells that form the midline. It established the tail end and bilateral symmetry.
How is a trilaminar embryo formed and what are its main components?
Cells migrate through the primitive streak of a bilaminar embryo in two waves:
1. Endoderm displaces hypoblast
2. Mesoderm spreads
- Ectoderm displaces the remaining epiblast
What are the germ layers of an embryo and what do they become?
- Ectoderm: Exterior (i.e. skin) and nervous system
- Endoderm: Lining epithelium of digestive tube and respiratory systems (including glands)
- Mesoderm: everything in between, including hollow structures. I.e. heart, muscle, CT, kidney, bladder.
What are the different parts of the early mesoderm?
- Notochord = axis
- Lateral Plate
- Prochordal plate - where ectoderm and endoderm contact
- Cardiogenic area - heart forming area just above prochordal plate
Where is the neural plate and what happens to it during embryo development?
Part of ectoderm.
It forms a NEURAL GROOVE in the centre, with two NEURAL CREST at the two peaks.
It then forms the NEURAL TUBE and the neural crests lie within the mesoderm.
What part of the mesoderm results in segmentation and how?
It forms pairs of Somites
What do somites form?
- Dermatome (skin of the segment)
- Scleratome (axial bone)
- Myotome (muscle of the segment)
What parts of the lateral folded embryo form the gut?
Endoderm + one layer of lateral plate mesoderm
What parts of the lateral folded embryo form the body wall?
Ectoderm + one layer of lateral plate mesoderm + myotome
What is the cavity of the lateral plate?
Coelomic cavity ('body cavity'). Mesoderm
Coelomic epithelium - one layer of mesodermal cells form epithelium on inside of cavity
What does the coelomic cavity form in the thorax and abdomen?
What are the serous membranes the the lining of the coelomic cavity forms?
- parietal (body wall)
- visceral (organs)
What is a teratogen?
Any agent that can disturb the development of an embryo or fetus.
What are the first 3 weeks of pregnancy called?
What are weeks 4-8 of pregnancy called?
What are weeks 9+ of pregnancy called?
What key steps happen during weeks 1-4 of a pregnancy?
- early blastocyst
- bilaminar embryo
- Trilaminar embryo
- somites begin
- neural tube
- beginning of head (folding)
What are the key features of organogenesis in pregnancy?
- most systems develop
- histogenesis (epithelial specialisation, glands etc)
- specific sensitive period where there is a possibility of maldevelopment
What are the key features of the foetal period?
- enormous growth in size: 5cm to 40cm
- tissue maturation and histogenesis
- crown rump = sitting height
- crown heel = standing height
What are the two segments of myotome in the body
- epaxial (posterior muscles of vertebral column)
- hypaxial (muscles anterior to verterbrae)
What are the layers of the body wall?
- parietal serous membrane
What are the ganglion near the spinal chord?
Dorsal root ganglion
They come from the dorsal (sensory) root instead of ventral (motor)
What are the main anatomical features of the spinal nerve?
Ventral root = motor
Dorsal root = sensory
Dorsal and ventral RAMI, which mix and go through the foramen as one, and then separate as mixed nerves = PRIMARY RAMI
Where does the Posterior and Anterior Rami go?
Ventral = hypaxial muscle + skin (cutaneous)
Dorsal = Epaxial muscle + skin (cutaneous)
What type of rami goes to intercostal nerves?
Thoracic ventral rami
What are some somatic structures?
- skeletal muscles
What are some visceral structures?
- smooth muscle
- cardiac muscle
What are the segments of the upper limbs?
What are the segments of the lower limbs?
What is the most common artefact of skeletal tissue?
Shrunken cells 'fall out' of lacunae so lacunae they appear empty.
What keeps the trachea open all the time?
Incomplete, C-shaped rigs of hyaline cartilage
What type of hyaline cartilage does not have a perichondrium?
This is found around the joints of bone
What does dead cartilage look like and why is it there?
In between hyaline cartilage and bone, may see lots of bluish patches = dead cartilage.
This matrix is calcified. New bone is forming, but it is not bone yet.
What does spongy bone look like under the microscope?
Filled with adipose tissue. Cells almost empty with nuclei in a corner somewhere.
Still has osteocytes in lacunae.
What are the main visceral compartments of the neck?
- carotid sheath
What does the carotid sheath contain?
main neuromuscular bundle in the neck
- jugular vein
- carotid artery
- vagus nerve (cranial nerve X)
What are the main muscles/bones around neck?
- posterior triangle
- hyoid bone
- digastric muscle
- strap muscles (mostly behind hyoid)
How is the sternocleidomastoid muscle attached?
Top is attached mainly to mastoid process.
Bottom attached to sternum and clavicle
How is the trapezius muscle attached?
Goes from back of neck to clavicle.
How is the digastric muscle connected?
Goes from behind the ear to the chin.
BUT it has two bellies with an intermediate tendon hooking to the hyoid bone.
Name the Deep Cervical Facia.
- pretracheal layer (in front of trachea)
- investing layer (goes around whole neck with pockets for trapezes and St-M)
- carotid sheath (jugular, carotid + vagus)
- prevertebral layer (layer in front of muscles in front of vertebrae)
What is the adams apple?
Thyroid cartilage. Part of larynx
What is the notch at the top of the sternum?
What bones make up the brain case?
- +/- sphenoid
What bones make up the face?
- zygomatic (cheeks)
What is the entire cavity of the skull?
What is the sticking out bone below ear?
What is the skull cap?
How do the bones at the top of the skull form vs the bottom of the skull?
Top = intramembranous ossification
Bottom = endochondral ossification
What muscles are outside of the thoracic wall?
2 x pectorals
What makes up the thoracic wall?
- ribs (costae)
- intercostal spaces = intercostal muscles + nerves and blood vessels
What are the parts of the sternum?
- manubrium (top)
- body of the sternum
Suprasternal notch at top
Sternal angle between manubrium and body
What does the sternal angle mark?
- Rib 2
- Superior Mediastinum is separated from rest of mediastinum by horizontal plan from sternal angle to T4
What are the different parts of the mediastinum?
Anterior (narrow space)
What is in the mediastinum?
- heart and its vessels
- phrenic and cardiac nerves
- thoracic duct
- lymph nodes
How many ribs are directly attached to sternum with hyaline cartilage?
6 or 7
What is the inner surface of the thoracic wall?
NOTE: this separates mediastinum from lungs
What is the vein/artery running vertically by the side of the sternum?
Internal Thoracic Artery
What is the upper limit of the mediastinum?
Rib 1 to T1 = thoracic inlet.
The venae cavae go from where to where?
body to RA
The pulmonary artery goes from where to where?
RV to lungs
The pulmonary veins go from where to where?
lungs to LA
a pair from each lung
The aorta goes from where to where?
LV to rest of body
What are the torso planes?
- midclavicular lines
- transpyloric plane (9th rib cartilage)
- transtubercular plabe (tubercle of iliac crest)
What is anterior to the tubercle of iliac crest?
anterior superior iliac spine
What are the torso regions?
b) umbillical region
d) L/R hypochondrium
e) L/R lumbar regions (flank)
f) L/R iliac regions
What are the main features of the abdominal wall?
- costal margin (end of ribs)
- lumbar vertibrae
- hip bones (mainly upper margins)
- parietal peritoneum
What are the abdominal muscles?
- External Oblique (downwards)
- Internal Oblique (upwards)
- Transversus (across)
Which abdominal regions does the liver lie?
Right hypochondrium and some epigastrium
Which organs are situated in the right iliac region?
- end of small intestine
- beginning of colon
What are the types of colon?
- ascending - right - lost mesentery
- transverse - movable, transverse mesocolon
- descending - left - lots mesentery
- sigmoid colon - left iliac region. Sigmoid mesocolon.
What is the cribiform plate?
Roof of nasal cavity with small nerves for smelling passing through it.
What are the three large fossa of the skull?
- posterior cranial fossae
What is the larger foramen in the skull?
What is in the centre of the middle fossa in the skull?
pituitary fosse for pituitary gland
quadrangular plate behind it
sella turcica (saddle)
The level of the skull drops after bars of the temporal bone into the posterior cranial fossa. What are these bars called?
Petrous part of the temporal bone
How big is the largest type of blood vessel?
How big are capillaries?
7 nano meters or less
What tissue surrounds the inside of BV walls?
What are the anatomical points on the outside of the heart?
- apex (bottom tip = LV)
- base (broader top end - LA and RA)
- diaphragmatic surface (RV)
What are the steps in systemic circulation?
LV - aorta - arteries - arterioles - capillaries - venules - veins - SVC and IVC - RA
What are the steps in pulmonary circulation?
RV - pulmonary trunk - LPA and RPA - capillaries in lungs - 2 pulmonary veins for each lung - LA
What is the joining together of blood vessels and what does it cause?
- collateral circulation
With anastomoses, what does survival of the tissue depend on?
- size of anastomoses
- sudden vs gradual block
- resilience of tissue
What tissue is not resilient to blood blockages?
- nervous tissue
What is stenosis?
Narrowing of arteries
What is a thrombus?
a blood clot that forms in a vessel and remains there
What is an embolism?
An embolism is the lodging of an embolus, which may be a blood clot, fat globule, gas bubble or foreign material in the bloodstream.
What is an aneurysm?
Ballooning of arterial wall. Therefore weakened wall and risk of rupture.
What insures unidirectional flow in veins and where ARENT these found?
Not in large veins
What aids the flow of blood through veins in the lower limbs against gravity?
What is a vena comitans and a neuromuscular bundle?
vena comitans = vein + artery together
neuromuscular bundle = vein + artery + nerve
What tissue fluid will return to blood?
Those in lymphatic capillaries.
Where is lymph not formed?
What are lymph nodes?
Filters. Small aggregates of defines related cells
What does enlargement of a lymph node mean?
- May mean cancer (metastases)
- disease/s of the lymph system
Which lymph nodes drain upper limbs?
- Thoracic wall
- abdominal wall above umbillicus
Which lymph nodes drain lower limbs?
- lower limb
- lower abdominal wall
what is the scale for histological sections?
The scale is very small: 1 micron (micrometre, μm or simply μ) : 1 millionth of a metre, 1/1000 mm.
What is the size of a general mammalian cell?
Varies between 2-100um
Give an example of tissue integration that forms an organ
The intestine: outer ring of muscle, used for movement
Middle and inner ring contain connective tissue
Inner layer features an epithelial lining for secretion and absorption
How do areas exposed to wear and tear manage their epithelial layers?
Often these areas will have a thicker layer of epithelium (stratified), to ensure maintenance of integrity. Basal cells may be capable of division, although cell replacement is a feature of all epithelium
How are epithelial layers named?
By the cells closest to the membrane/furtherest from the underlying connective tissue
What are columnar cells often used for?
Absorption, and movement of mucus. They may feature microvilli, which are important for absorption, or Cillia, which are able to 'beat' mucus along the surface of a cell. Cillia may be seen especially in layers featuring goblet cells
What are the four main layers of skin?
- stratified squamous
- dead and living cells
2. Dermis – CT
4. Deep Fascia
What are the different parts of the Dermis?
The dermis is connective tissue
a) epidermal Pegs and dermal papillae
b) Papillary (loose) – vascular and nervous papillae
c) Reticular (dense) – collagen fibers
What are the defining features of thick skin and where is it found?
- thick keratin layer, therefore thick epidermis
- waterproof due to thick keratin layer
- no hair
- no sebaceous glands
- palms and soles
What are the different parts of the epidermis?
Epithelial cells – keratinocytes
1. Basal layer
- cuboidal/columnar cells
2. Stratum Spinosum
- spiny (prickle-cell) layer
- interdigitating cell processes from melanocytes and desmosomes
- attached to basement membranes by semi-desmosomes
3. Stratum Granulosum
- key to keratinization – keratohyalin granules
- these first 3 are living part of epidermis
4. Stratum Lucidum
- clear layer of dead cells after stratum granulosum
5. Stratum Corneum
- keratin layer
How does keratinization take place?
- keratins – a group of proteins
- Main site of transition: stratum granulosum – keratohylin granules
- filaments aggregated by filaggrins – this protein binds keratin fibers in epithelial cells
- /filaggrin monomers can become incorporated into the lipid envelope
- cell membranes thickened by keratin, other proteins and lipids.
- The cell envelopes and dies
- Stratum corneum – lipid-protein coat acts as an epidermal water barrier
What are melanocytes?
- neural crest origin
- main body usually clear
- located in basal layer
- cell processes pass between keratinocytes
- mature melanosomes in processes which are passed on to keratinocytes
Describe the non-epithelial cells in the epidermis
a) Langerhans cells
- scattered among keratinocytes
- antigen presenting cells (functionally related to macrophages)
b) Merkel Cells
- associated with sensory nerve endings
c) Sensory nerve fibers
d) Occasionally lymphocytes
In terms of glands, what are the 3 modes of secretion?
a) merocrine (eccrine)
- most types of sweat glands
- very little or no loss of cytoplasm
- When secretory granules released, they take a bit of cytoplasm with them and so cell is shorted. But still remains functional.
- has accumulated a lot of products and when it releases its secretion the whole thing explodes and dies, releasing them
What are the features of merrocrine (eccrine) sweat glands?
- mostly merocrine (eccrine)
- coiled secretory part deep in dermis
- surrounded by myoepithelial cells
- ducts travels to surface
- duct of sweat glands have a characteristic feature – stratified cuboidal with two layers
What are the features of apocrine sweat glands?
- larger lumen
- thicker secretion
- hormone dependent
What are the features of a hair follicle?
- keratinous shaft
- surrounded by epidermal sheath
- hair ‘bulb’ - germinative zone
- papilla - at the end of the shaft
What are the hair growth cycles?
1. anagen – growth
2. catagen – stoppage of growth (just sits there)
3. telogen – long rest, follicular atrophy, shedding
What are the characteristics of a subaceous gland?
- A small gland in the skin which secretes a lubricating oily matter (sebum) into the hair follicles to lubricate the skin and hair.
- holocrine glands – disintegrate to release secretion
- cells with lipid droplets
List some modified glands:
- glands in the eyelid
- ceruminous glands (in ear canal)
List the three major plexuses and give characteristics of blood vessels in skin.
1. subcutaneous: hypodermis
2. cutaneous: junction of papillary/reticular dermis
- perforating vessels from deeper tissues
- note: mycutaneous flaps. Skin with a little bit of underlying muscle used for transplants to that patch won’t just die
- arteriovenous anastomoses
- cutaneous circulation and temperature regulation
What is the ‘rule of 9s’?
Estimation of skin loss in burns
- head-neck: 9%
- Each upper limb: 9%
- Each lower limb: 18%
- Thorax: 9% for each side
- Abdomen: 9% for each size
- In children, head accounts for more
What are the components of the hypodermis?
- NOTE: termed ‘superficial fascia’ in gross anatomy
- ‘subcutaneous tissue’ of surgery
- variable amounts of fat. Some devoid – eyelids etc.
- provides some mobility
- blood vessels and nerves of skin in this layer
- almost non-existent in some areas, i.e. parts of ear, nose etc
How is thick skin recognized on a slide?
The dark line of the stratum corneum.
What are the reddish streaks in-between pale portions in the hypodermis of thick skin?
Pale portions – fat
Streaks – CT partitions between ‘lobules’ of fat
What do the ducts of sweat glands look like on slides (not close up)?
Darker streaks in dermis.
The terminal portions of the ducts pass through the stratum corneum, where they are visible as just a series of ‘holes’ stacked together.
What will a duct look like close up?
- pink stained secretory part
- darker ducts – stratified cuboidal with two layers
- layer of thinner cells around secretory portion – myoepithelial cells
- they zig-zag across, so may find them in bunches
What will the cells of the stratum corneum look like close up?
- no nuclei
- cell boundaries not clear
What will a pacinian corpuscule look like under the microscope?
- Mechanoreceptor – nerve endings in the skin
- Concentric layers in large round or oval outlines
What will thin skin look like under the microscope?
- keratin layer rather thin
- the rest of the epidermis may also be much thinner
- stratum granulosum, although prominent, may also be thinner
The scalp is essentially thin skin. What else will be seen deep to the hypodermis?
Occipitofrontalis: A sheet of skeletal muscle stretching from the occipital to the frontal region.
It has two parts: occipital and frontal.
Aponeurosis: large dense fibrous sheet connecting the two
What does a subaceous gland look like under the miscroscope?
- most of the cells contain multiple droplets of oily secretion, giving the cytoplasm a foamy appearance
- at one end (close to follicle) one can see disintegrating cells without nuclei
What are the three types of joint?
1. Fibrous – no joint cavity and are connected via fibrous CT.
2. Cartilage. Connected by:
What are sutures?
Fibrous joints that are indicators of growth mechanism.
The unossified areas are dense fibrous tissue, which becomes narrower as bones grow.
They disappear with age.
What are syndesmoses?
Other fibrous unions (not sutures).
Example – inferior tibiofibular
What are the characteristic features of cartilaginous joints made from hyaline cartilage and white fibrocartilage?
- growth mechanism
- joint = ‘synchondrosis’
- no movement
- epiphyseal plate
- end of growth period = synostosis = fusion of adjacent bone
- last one to disappear = 25 years
b) White Fibrocartilage:
- slightly deformable
- joint = ‘symphysis’
- bone surface covered with hyaline cartilage
- thick disk of white fibrocartilage in between
- i.e. bodies of vertebrae and pubic symphysis
What are the characteristic features of synovial joints?
- bone ends surrounded by mesenchyme
- secondary cavitation (allows movement)
- smooth surface = hyaline cartilage
- additional stability
What are the components of a synovial joint?
1. Articular cartilage
- hyaline, with exceptions
- generally reciprocal thickness and curvature
- smooth, white tissue that covers the ends of bones where they come together to form joints
2. Fibrous capsule
- may have intracapsular ligaments
3. Synovial membrane
- epithelium with loose CT
- synovial fluid
4. Possibly bursae
5. Intra-articular discs/menisci
- white fibrocartilage
- facilitate movement and reduce incongruence
- ensure optimal distribution of synovial fluid
6. Fat pads
- extra synovial
- non-weight bearing areas
What determines the subtypes of synovial joints?
- shapes of articular surfaces
- hinge, pivot, saddle, ball-and-socket
- axes/degree of freedom may be more useful
Name two examples of a synovial joint:
Femur and hip bone.
Cup-like socket = acetabulum
Describe the knee joint.
- femur + tibia
- fibrocartilaginous menisci within joint
- two ligaments cross each other (cruciate) in the joint + external ligaments
What are bursae?
- CT sac with synovial lining. Fluid filled sac.
- Constant and variable bursae
- Bursae between skin and bone
- Some communicate with joint cavity
- Adventitious bursau – may occur in certain individuals
Which body wall segments are in the upper limbs?
C5 to T1
Which body wall segments are in the lower limbs?
L2 to S3
Which rami control the limbs?
The ventral rami of the corresponding spinal nerves.
NOTE: all musculature is hypaxial
For the hands and feet, name a preaxial structure and a postaxial structure.
Preaxial – thumb and big toe
Postaxial – little toe/finger
For the upper limbs, what do flexion movements do?
Carry the distal part forwards.
NOTE: all anterior surfaces of the upper limbs are developmentally ventral (except the thumb).
For the lower limbs, which surfaces are ventral and which are dorsal?
At hip: anterior surface is ventral
Knew to ankle: anterior surface is dorsal
Foot: Sole (planta) is ventral, and top (dorsum) is dorsal
Describe the flexor/extensor muscles in the upper limbs.
- anterior = flexors
- posterior = extensors
Describe the flexor/extensor muscles in the lower limbs.
- anterior compartment of THIGH has flexors of hip and extensors of knee
- posterior compartment of THIGH has extensors of hip and flexors of knee
- abductors of the HIP = gluteal region
- adductors of HIP = significant medial compartment
- anterior compartment of (lower) LEG has extensors
- posterior compartment of (lower) LEG has flexors
What are the girdle bones?
Upper limbs = ‘pectoral girdle’
Scapula and Clavicle
Lower Limbs = ‘pelvic girdle’
What are the two divisions of the ventral ramus?
Dorsal division: extensors
Ventral division: flexors
Describe the brachial plexus.
- 5 nerves, 4 from the neck
- 3 ‘trunks’
- each drunk has two divisions
- divisions = ‘chords’
Describe the lumbar and sacral plexuses.
- simpler pattern (no trunks or chords)
- Part of L4 and all of L5 join sacral nerves
List 3 sutures of the skull:
1. Coronal Suture: between frontal and parietal bones
2. Sagittal suture: median plane between parietal bones
3. Lamboid Suture: between parietal and occipital bones
What are the bones in the arm?
- humerus (big)
- radias (lateral and preaxial)
- ulna (medial and postaxial)
What are the bones in the legs?
- femur (big)
- tibia (medial and preaxial)
- fibula (lateral and postaxial)
What are the bones in the hand?
- Carpal bones – small irregular bones
- Metacarpal – one leading to each digit
- Phalanges = fingers and toes
- Thumb = pollex = two phalanges = proximal and distal
- Fingers = 3 phalanges = proximal, middle and distal
What are the bones in the feet?
- Tarsal bones – small irregular bones
- Metatarsal – one leading to each digit
- Phalanges = fingers and toes
- Big toe = hallux = two phalanges = proximal and distal
- Toes = 3 phalanges = proximal, middle and distal