Overview Of Nervous System & Spinal Cord External Features & Scalp Flashcards
Describe the CNS embryological classifiction (with mentioning cavity of each)
Forebrain (prosencephlon): median diencephalon (3rd ventricle) + 2 telencephalons (2 lateral ventricles)
Midbrain (mesencaphalon, cerebral aqueduct of Sylvius)
Hind brain (rhombencephalon, 4th ventricle)
Describe arrangement of grey and white matter throughout CNS
Spinal chord, white matter surrounds H-shaped grey matter
Brain stem, scattered nuclei of grey matter in white matter
Cerebral hemispheres, deep nuclei & on the surface forming cortex
State functions of the CNS
- Maintenance of homeostasis
- Recieving and integrating sensory information
- Integrating information
- Controlling muscles and glands
- Maintaining mental activity
Describe site & length of spinal cord
S: occupies upper 2/3 of vertebral column, begins a atlas vertebra as continuation of medulla oblongata, ends at level of disc between L1&2 at birth it ends at L3.
45 cm
Mention the enlargements of the spinal chord
- Cervical enlargement gives origin to brachial plexus (C4 to T1)
- Lumbar enlargement gives origin to lumbar and sacral plexuses (L1 to S4)
The tapering lower end if s.c. Is called …., a filament of … mater extends from its end then attaches to …., this is called….
Conus medullaris
Pia
Back of coccyx
Filum terminale
…..&…..divide the spinal cord into rt & lt halves
Anterior median fissure
Posterior median septum
Locate pseudounipolar neurons
In posterior root ganglion carried by posterior root of spinal nerves
All ant rami form plexuses except ……
The 12 thoracic
Mention the ant rami sending white ramus communicants
12 thoracic + upper 2 lumbar
Both rami of …are purely motor
C1
Write short note on recurrent meningeal nerve
It is the first branch of mixed spinal nerve after leaving IVF & re-enters through it to supply dura, periosteum, b.v. & IV discs. Plays a role in referred pain and occipital headache
All sacral & coccygeal segments are located opposite….
L1
Describe direction of spinal nerves
C1-2, horizontal
C3-T12, oblique
L1-Co, vertical
Describe exit of spinal nerves from the vertebral canal
C1-7 above corr disc
C8 below C7
T1-L5 below corr disc
S1-4 pass via ant & post sacral foramina
S5 & Co sacral hiatus
Mention the structure occupying the lower 1/3 of vertebral canal
Cauda equina
GR: 4th & 5th lumbar nerves are most liable to compression
As the size of spinal nerves inc in downwards direction while the size of intervertebral foramina dec
….is largest spinal nerve
S1
The dura & arachnoid end at ….
S2
Mention contents of subarachnoid space
CSF
Filum terminale
Ligamentum denticulatum (21 teeth)
Subarachnoid septum extends from post med septum
Site & uses of lumbar puncture
S, above or just below the tip of 4th lumbar spine
U, diagnostic; to measure pressue, sample or inject air for contrast in C-ray
Therapeutic, relieve inc intracranial tension or inject abx or spinal anesthesia
Describe the extent of the scalp
Ant: supra-orbital margin
Post: external occipital protuberance and highest nuchal line
Lat: superior temporal line
Mention the result if density of CT of the 2nd layer
- Infections tend to remain localized causing pain
- Wounds do not gap
- Injury to vessels leads to profuse bleeding as walls are adherent to CT septa thus can’t contract or retract
Describe attachment of epicranial aponeurosis
Ant: frontal bellies of occipito-frontalis
Post: occipital bellies of o.f.
Lat: sup temporal line
GR: wounds reaching aponeurotic layer gap
Due to muscle contraction
Compare frontal bellies & occipital bellies of o.f.
F:
Origin: wider partly united in midline; each arises the skin of eyebrows
Insert in epicranial aponeurosis
Supplied by temoral branch of facial nerve
Pull scalp forwards and raise eyebrows
O:
Origin: narrower separated from each other by an extension of epicranial aponeurosis, each arises from lat 2/3 of the highest nuchal line
Inserted as before
Post auricular branch of facial nerve
Pull scalp downwards
GR: Black eye occurs with injury of 4th scalp layer
As it is composed of loose areolar CT allowing spread of blood below the aponeurosis, it cannot spread to the neck due to attachment of occipital bellies to bone, but it can spread forward since the frontal bellies is not attached to bone thus the blood collects in the eyelid.
What happens in case of injury of vessels of 5th layer
Collection of blood (hematoma) that takes the shape of bone.
Mention arteries of the scalp
- Supraorbital & supratrochlear
- Superficial temporal artery
- Posterior auricular artery
- Occipital artery
Mention branches originating from ICA & areas they supply
Supraorbital & supratrochlear
Skin of forehead, s.o. supplies skin till level of the vertex
Enumerate branches of each:
1. Superficial temporal art
2. Post auricular
3. Occipital art
- Transverse facial, auricular, middle temporal, glandular to parotid & terminal (frontal & parietal)
- Auricular, occipital, stylomastoid
- Auricular, occipital, mastoid, sternomastoid, descending, muscular & meningeal
Superficial temporal art supplies ….
Skin of temple & side of scalp
….ascends above post belly of digastric while ….ascends below it ….
Posterior auricular art
Occipital art
Supraorbital & -trochlear veins unite to form ….., which drains into….forming……that ends in…..
Facial vein
Ant division of retromandibular vein
Common facial vein
IJV
Retromandibular vein is formed from….
Union of superficial temporal and maxillary veins
Describe course of posterior auricular vein
Unites with post division of retromandibular vein forming EJV
Occipital vein drains into …..
Suboccipital venous plexus
What is the importance of emissary veins?
They help to reduce venous pressure inside the cranial cavity
Mention nerves in front of the auricle
Sensory:
Supraorbital, supratrochlear, zygomaticotemporal, auriculotemporal
Motor: temporal branch of facial nerve
Mention nerves behind the auricle
Sensory:
Greater auricular, lesser occipital, greater occipital, third occipital nerves.
Motor: posterior auricular bracg of facial nerve
Nerves which originate from C2 only
Lesser occipital, greater occipital
The skin up to vertex on the front is supplied by ….., while on the back ….
Supraorbital
Greater occipital
Describe lymph drainage of scalp
Pre-auricular, parotid LNs
Post-auricular, mastoid & occipital LNs
