Title: Anatomy / part 4

Q: Diencephalon - parts
A: thalamus (intrinsic regulation of the body), epithalamus, hypothalamus, hypophysis

Q: mesencephalon - parts
A: tectum, tegmentum, crura cerebri

Q: rhombencephalon - parts
A: pons (purple)
 cerebellum (combined movements, complex movements, adaptation movements)
medulla oblongata (green, centrum for breathing and blood regulation)

Q: spinal cord
A: Attached to the medulla oblongata follows the spinal chord which ends at level of first lumbar vertebra.
The segments of the spinal chord are defined by the spinal nerve.
Between each segment a nerve exits. The lower you go, the larger the distance we get between the spinal root and the real exit of the nerve. In the lower part we can only find spinal nerves, this is called cauda equina (horse tail) (green). Inside of the spinal chord we find grey matter, while white matter is on the outside.
Intumescences describes the thickening of the spinal chord, there are 2. The terminal cone is at the last exit of the terminal fiber.
- 4 Segments:
1. C8 (Cervical, just 7 vertebra),
2. Th12 (Thorical),
3. L5 (Lumbar),
4. S5 (Sacral)
The nerve always exits below the vertebra

Q: meninges
A: The meninges surrounds the entire brain and subdivides it into smaller spaces.
Pachymeninx: dura mater encephali (falx cerebri, tentorium cerebelli) / spinalis
Leptomeninx (Bindegewebsschichten der Hirnhäute):
- arachnoidea mater (separated from the brain by liquor) encephali (brain) /spinalis (spinal chord)
- pia mater (directly connected to the brain, not separable. Also covers the surface of the spinal chord) encephali / spinalis
There exist multiple places with liquor (exists physiologically): epidural space / subdural space (below the dura mater) / subarachnoidal space (below the arachnoidea)
In case of a ruptured anoerism, these spaces often fill with blood and accelerate the time needed to bleed out.

Q: Intracranial blood vessels
A: Artries: circle of Willis, 3 cerebral and 3 cerebellar arteries. The circle of Willis is just a circular interconnection between multiple arteries which ensure a good blood flow.
Veins: cerebral sinus (inside of dural duplicature, very different from veins in other body parts )

Q: Liquor spaces
A: Liquor describes the fluid around the brain. We can divide it into 2 liquor spaces (in the brain):
internal (ventricles, all connected to each other)
- 1st and 2nd ventricle → telencephalon (We have an interventricular foramen (hole) between 1/2 and 3)
- 3rd → diencephalon (There is a cerebral aqueduct between 3 and 4)
- 4th → rhombencephalon (There are apertures from 4 to external liquor space)
- central canal
external (subarachnoidal space)

Q: Liquor function
A: The main function is to separate the brain from hard surfaces (could lead to necrosis), reduction of weight by ca. 90% (due to floating???? and shock absorption. The disadvantage is a slower movement reaction (shaking trauma in infants).
Liquor is very useful diagnostically to recognize problems with the brain and cranium (skull). It needs to be drained if the intercranial pressure rises too much. The liquor is produced in the choroid plexus and it drains through arachnoideal granulations.

Q: Peripheral nervous system
A: There are 12 pairs of cranial nerves: olfactory nerve , optic nerve, oculomotoric nerve , trochlear nerve , trigeminal nerve , abducens nerve , facial nerve , vestibulocochlear nerve ,glossopharyngeal nerve , vagal nerve , accessory nerve , hypoglossal nerve
Most of the nerve pairs are responsible for processes surrounding the face.
Additionally there is 1 pair of spinal nerves for each segment of the spinal chord: cervical, brachial, lumbal and sacral plexus

Q: Vegetative nervous system
A: Covers everything we don`t control (also fight or flight (sympatic, thoracic spinal cord) vs. rest and digest (parasympatic, mainly vagal nerve) and the enteric nervous system).
The organs influenced by this nervous system: eye, lacrimal and salivatory glands , vessels of the head, heart, lungs, stomach, liver, pancreas, kidneys, bowels, parts of colon and rectum, urinary bladder, genitals.

Q: eyeball - layers
A: It`s a hollow sphere with 3 layers, connected to the optic nerve.
The layers:
tunica fibrosa bulbi:
- sclera: white part of eye, continuously
- cornea: where you can see through, continuously
- conjunctiva: (outer most layer): art that gets red or inflamed (Schleimhaut Augenlid innen)
tunica vasculosa bulbi (highly vascularised layer):
- choroidea (Aderhaut)
- iris: eye color and border of pupil
- ciliar body Muskeln
tunica interna bulbi (yellow)
- retina (Netzhaut)

Q: eyeball - optic apparatus
A: cornea, anterior eye chamber, iris, posterior eye chamber with lens and ciliar body with zonular fibers, vitrious body
The posterior eye chamber is filled with aqueos fluid (humor) to regulate intraocular pressure.

Q: Internal eye muscles
A: The shape of the eyeball is very important.
There are mechanisms to regulate the pupil (enlarge or minimize):
- dilatator pupillae (sympatic) and sphincter pupillae (parasympatic) muscles
- miosis, mydriasis
The ciliar muscles are used to change the shape of the lens to focus an image at different distances.

Q: retina
A: The image get projected onto the retina where the rods (for black and white) and cones (for colour) for
convert it into a signal to process it.
If the image is exactly on the optic nerve (papilla), this will result into a blind spot because there are no photoreceptors.

Q: eye - accessory structures
A: All the things for
moving (orbicularis oculi muscle, levator palpebrae superioris muscle),
cleaning (external eye muscles) and
lubrification (tarsus, Meibom-and Zeis-glands, lacrimal glands and lacrimal structures) of the eyeballs.

Q: ear - general
A: The organ of hearing and of equilibrium combined (we need both ears for both). Can be subdivided into an external, middle and inner ear.

Q: middle ear
A: The tensor tympani muscle and stapedius muscle can modulate the hearing
sensation. This is to prevent damage to the inner ear from too loud sensations.

Q: inner ear + cochlea
A: The organs of hearing and equilibrium are located here. They are inside of a membraneous and osseous labyrinth.
The cochlea→ 3 levels filled with perilymph (scalae) and endolymph (duct)
Scalae are at cochlear tip (helicotrema) connected, ending at round (cochlear window) / oval window (vestibular window)
Organ of Corti → cochlear nerve of vestibulocochlear nerve.
For hearing we have approx. 15.000 auditory sensory cells (hair cells) which are connected by gelatinous layer (i.e. tectorial membrane) so that the reaction is synchronised.

Q: organ of equilibrium
A: The organ of equilibrium is located in the inner ear.
The organ of equilibrium is filled with endolymph (liquor) and subdivided in 2 bulgings (Utriculus, Sacculus) with utricular maculae (horizontal acceleration receptors) and saccular maculae (vertical acceleration receptors) and
3 semicircular canals at which end the cupola lies (rotational acceleration in all 3 axes) → vestibular nerve of vestibulocochlear nerve.
It works by deflecting ciliae by shear force (which are also connected)

Q: skin - layers
A: The skin is subdivede into 2 main layers:
- epidermis: stratified squamous epithelium
- dermis (under the epidermis): high-fiber connective tissue, capillaries, nerves, cutaneous glands (sweat, sebaceaous, scent)
and the subcutis (not a part of the skin, below it): loose connective tissue, fat, capillaries,
nerves

Q: Sensory organs of the skin
A: There are multiple nerve ending corpuscules (mechanoreceptors) in the dermis:
- Merkel-cells (epidermis)
- Meißner-tactile corpuscules (dermis)
- Vater-Pacini-lamellar corpuscules (subcutis)
But also free nerve endings can be found mostly in dermis, hair follicles (mechano-, pain, pressure,
temperature receptors).

Q: Skin appendages
A: - Nails safe the osseous tip of our finger. If the nail was to short, the bone would be too exposed. It is only attached to the nail root, where the growth zone is.
- Cutaneous glands: sweat, scent, sebaceous
- Hairs (lanugo, terminal): arrector pili muscle (for temperature regulation, “goosebumpsˮ)