cranium, meninges and brain

Question 1

bones of cranium

Answer 1

frontal two parietal two temporal occipital sphenoid (deep in centre) and ethmoid (above nose)

Question 2

bones of facial skeleton

Answer 2

2 maxilla 2 zygoma (bones of cheek) 2 nasal 2 lacrimal 2 palatine (palate) 2 inferior nasal conchae (increase SA of nasal cavity to warm air)

vomer (middle of skull) mandible (jaw bone)

Question 3

anterior view of skull DIAGRAM

Answer 3

d

Question 4

posterior part of skull DIAGRAM

Answer 4

d

Question 5

what are sutures

Answer 5

fibrous joints allowing little movement

Question 6

infant skull + fontanelles DIAGRAM

Answer 6

anterior fontanelles close within 18 months, posterior within 2 months- thus sutures not complete as bones need to move as baby comes out of mother)

Question 7

superior view of skull DIAGRAM

Answer 7

jj

Question 8

pterion and clinical significance DIAGRAM

Answer 8

weakest region where greater wing of sphenoid, frontal, parietal and temporal bones join damage can rupture middle meningeal artery= extradural haematoma

Question 9

cranial base and anterior cranial fossae DIAGRAM (bones, lobes and foramina)

Answer 9

can be divided into anterior, middle and posterior fossae anterior fossae is above nasal fossae, containing sphenoid, cribriform plate, foramen cecum, foramina of cribiform plate and frontal lobes

Question 10

middle cranial fossae DIAGRAM

Answer 10

above pharynx, containing foramen lacerum, foramen ovale, foramen spinosum, foramen rotundum, greater wing of sphenoid, optic canal, superior orbital fissure, carotid canal and temporal lobes

Question 11

posterior cranial fossae DIAGRAM

Answer 11

largest fossa containing brainstem and cerebellum, NOT occipital lobes, foramen magnum, jugular foramen, internal acoustic meatus and hypogloassal canal

Question 12

foramina and nerve fibres that pass through

Answer 12

1- cribiform plate 2 (and opthalmic artery)- optical canal 3, 4, 5 (opthalmic nerve, 1st branch of trigeminal nerve),6 (and superior opthalmic vein)- superior orbital fissure 5 (maxillary nerve, 2nd part of trigeminal nerve)- foramen rotundum 5 (mandibular nerve, 1st part of foramen ovale)- foramen ovale middle meningeal artery+ vein- foramen spinosum internal carotid artery- carotid canal 7,8 (and labrynthine artery)- internal acoustic meatus 9, 10, 11 (and internal jugular vein)- jugular foramen 12- hypoglossal canal medulla, vertebral artery and spinal roots of 11th nerve- foramen magnum

Question 13

tissue components of scalp and significance of blood supply

Answer 13

SCALP S- skin C- connective tissue A- aponeurosis L- loose areolar tissue P- periosteum: emissary veins can cause infection

Question 14

meninges and layers of dura mater

Answer 14

tough dura matter, thin arachnoid mater and thin pia (attached to brain) dura mater has outer periosteal and inner meningeal layer, which separate to form intradural venous sinuses

periosteal layer lost as it fuses with skull at foramen magnum, so only inner layer goes down vertebral column

Question 15

dural folds and sinuses DIAGRAM

Answer 15

dura mater follows shape of brain, so forms folds falx cerebri (ie cerebrum)fold- separates cerebral hemispheres tentorium cerebelli (sounds like cerebellum)- separates occipital lobes and cerebellum/brainstem

venous sinus is depression of inner layer- depression which forms falx cerebelli forms superior sagittal sinus: sinus penetrates arachnoid mater to allow CSF to be reabsorbed

transverse sinus along tentorium cerebelli, cavernous sinus are between temporal bones and sella turcica

Question 16

brain herniation- what is it

Answer 16

increased pressure of brain due to a SPACE OCCUPYING LESION eg bleeding

causes parts of brain to shift beyond dural folds and compressing another region

Question 17

subfalcine herniation DIAGRAM

Answer 17

frontal lobes herniate under flax cerebri- no clinical signifcance

Question 18

uncal herniation

Answer 18

uncus of temporal lobe herniates below tentorium cerebelli, compressing midbrain/brainstem= loss of conciousness

Question 19

tonsillar herniation

Answer 19

cerebellar tonsils move down through foramen magnum to compress medulla

Question 20

CSF formation and drainage

Answer 20

choroid plexus in each ventricle produces CSF laterals drain into 3rd via interventricular foramina, then 4th via cerebral aqueduct, then subarachnoid space, the dural venous sinuses via arachnoid villi

Question 21

blood supply of brain+ anterior supply DIAGRAM

Answer 21

2 types- anterior (internal carotid) and posterior (vertebro basilar) common carotid splits into internal/external at C4, and internal enters cranium via carotid canal, and has NOT branched yet then divides into anterior cerebral (supplies medial surface of hemispheres and superior part of lateral) and middle cerebral artery (main branch going through transverse fissure to supply lateral part)

Question 22

posterior blood supply

Answer 22

vertebral arteries from subclavian arteries go through transverse foramina of cervical verebra, and divide to form anterior and posterior spinal arteries then unites to form basilar artery, which lies on pons- basilar divides into pontine arteries and posterior cerebral arteries

Question 23

circle of willis DIAGRAM

Answer 23

connects anterior and posterior blood supplies- anterior cerebral arteries connected by anterior communicting, and middle and posterior connected by posterior communicating artery

Question 24

venous drainage

Answer 24

cerebral veins first drain into dural venous sinuses- superior and inferior sinuses meet at confluence of sinus THEN internal jugular vein

Question 25

signifiance of cavernous sinus

Answer 25

contains internal carotid and many nerves- emissary veins allow extracranial infections to reach inside (cavernous sinus)- damage to nerves and internal carotid

Question 26

lateral view of skull

Answer 26

temporomandibular joint where many problems occur

Question 27

what is ventral surface of brain

Answer 27

when brain taken out of cavity and turned upside down ie where all nerves can be seen

Question 28

what are arachnoid granulations

Answer 28

holes through which CSF are reabsorbed

Question 29

coronal section through hypothalamus

Answer 29

dd

Question 30

horizontal section

Answer 30

Question 31

signficance of deep lacerations

Answer 31

deep lacerations to scalp bleed a lot because-

bleeding vessel can’t be closed by occipitofrontalis muscle- there are also many anastamoses, and vasconstriction inhibited

Question 32

subdural haemorrhage

Answer 32

destruction of cortical veins= accumulation of VENOUS blood (not arterial like extradural)- often crescent shaped