Skull anatomy

Question 1

the mandible articulates via which joint?

Answer 1

the mandible articulates via the synovial temporomandibular joint

the rest of the 21 bones are fibrous (there are 22 bones in the skull)

Question 2

we call the cranial vault which protects the brain and is made up of 8 bones the = ________

whereas, we call the facial skeleton + bones of the jaw (14ish bones)= ________

Answer 2

we call the cranial vault which protects the brain and is made up of 8 bones the = neurocranium n.b. Fracture here lead to meningeal ruptures

whereas, we call the facial skeleton + bones of the jaw (14ish bones)= viscerocranium

Question 3

what is a basal skull fracture (aka basilar skull fracture)

Answer 3

Basilar skull fractures, usually caused by substantial blunt force trauma, involve at least one of the bones that compose the base of the skull

Basilar skull fractures most commonly involve the temporal bones but may also involve the occipital, sphenoid, ethmoid, frontal bone, parietal,

Question 4

what part of the skull does the sternoclaidomastoid attach to?

Answer 4

The sternocleidomastoid muscle originates from two locations: the manubrium of the sternum and the clavicle. It travels obliquely across the side of the neck and inserts at the mastoid process of the temporal bone of the skull by a thin aponeurosis.

Question 5

where is ur inner ear located in skull?

Answer 5

• Inner ear (cochlea, semi-circular canals) housed within **petrous part of temporal bone **
  n.b. When nerve passes through internal acoustic meatus, travels to inner ear

Question 6

what parts of the skull does the spehnoid bone connect?

Answer 6

sphenoid bone connects facial skeleton and neurocranium

Question 7

medial and lateral pterygoid muscles (muscles of mastication) attach to which bone of the skull?

Answer 7

the medial + lateral pterygoid muscles ; they attach to the pterygoid plates of the sphenoid bone

Question 8

where does the pituitary gland sit?

Answer 8

Sella turcica (‘TURKISH SADDLE’) an indent in sphenoid bone - pituitary gland sits here

Question 9

dura mater attaches at the _______

what are the 2 layers of dura mater called??

Answer 9

dura mater attaches at the clinoid processes

n.b. dura mater means ‘hard mother’ latin; dura mater has a periosteal layer which is atttached directly to the skull + then it has the meningeal layer which pulls alway from the periosteal layer sometimes to create ‘dural folds’= these dural folds are called dural venous sinuses its where the used blood goes in brain

Question 10

what notch does the brainstem pass through

Answer 10

The BRAINSTEM PASSES THROUGH TENTORIAL NOTCH

The brainstem is the structure that connects the cerebrum of the brain to the spinal cord and cerebellum. It is composed of three sections in descending order: the midbrain, pons, and medulla oblongata.

Question 11

where in the skull is the crista galli and why is it clinically significant

Answer 11

Crista galli (cocks coombe on top of cockerel head)- bony process part of the ethmoid bone; this is where falx cerebri attaches, either side of crista galli is the cribiform plate (where olfactory nerves travel through)

Question 12

what are fontanelles of a foetal skull + their function

Answer 12

• Fontanelles (large sutures) allow:
• Growth of brain
• Skull** flexibility during birth **
• Otherwise, pressure exerted on fully fused skull would fracture during birth
• Facial skeleton underdeveloped but neurocranium more developed
• Fontanelles are fibrous membranes, palpable deep to scalp - “soft spots”
• Include the:
• Anterior fontanelle - closes at ~ 18 months - diamond shape
• Posterior fontanelle - closes at ~ 12 months - triangle shape (this + anterior allow to identify bby head orientation)
• Paired sphenoidal fontanelles
  Paired mastoid fontanelles

Question 13

which artery passes through foramen spinosum

Answer 13

** Middle meningeal artery** passes through foramen spinosum

it supplies dura but is outside it
Travels right underneath to pterion

if you lacerate this artery= intracranial bleed called extradural haematoma

Question 14

which foramen does the internal jugular vein travel through

Answer 14

internal jugular vein travels through jugular foramen

Question 15

the internal carotid artery travels through the skull along which canal

Answer 15

the internal carotid artery travels through the skull along carotid canal

its an oblique passageway through skull for internal carotid canal then the artery goes OVER foramen lacerum (IS NOT REAL FORAMEN ITS FULL OF CARTILAGE; but in cadaver looks like hole cuz cartillage decays) to go into cavernous sinus and into brain

Question 16

explain anatomy of olfactory nerve (CN I) i.e. where is it in brain

Answer 16

the olfactory nerve runs inferiorly from olfactory bulb through perforated cribriform plate of ethmoid bone to enter nasal cavity

Question 17

explain anatomy of optic nerve (CN II)
i.e. where is it in brain

Answer 17

Optic (CN II)
Traverses optic canal to enter orbit to get to posterior part of eyeball

Question 18

which 3 cranial nerves pass through superior orbital fissure

Answer 18

Oculomotor (CN III), Trochlear (CN IV), and abducens (CN VI) - all pass through superior orbital fissure

• Oculomotor emerges from midbrain
• Trochlear emerges from posterior surface of midbrain - only cranial nerve to do so (rest emerge anteriorly)
• Abducens emerges from pons
  All 3 pass through the superior orbital fissure to enter the orbit

Question 19

where does the trigeminal nerve (CN V) emerge from

Answer 19

• Emerges from lateral surface of pons and splits into 3 branches
• Ophthalmic (V1) - traverses superior orbital fissure to enter orbit ;reaches face by exiting through supraorbital foramen
• Maxillary (V2) - leaves cranium by passing through foramen rotundum; reaches face by passing through infraorbital foramen
• Mandibular (V3) - runs through foramen ovale ;reaches face via mental foramen

Question 20

where does the facial nerve (CN VII) emerge from

Answer 20

the facial nerve (CN VII) =emerges from pons, passes through internal acoustic meatus then runs through petrous temporal bone (facial canal) and exits skull via stylomastoid foramen

Question 21

where does the vestibulocochlear nerve (VIII) emerge from

Answer 21

vestibulocochlear nerve (VIII) emerges from pons and enters the internal acoustic meatus (similar to facial nerve)

Question 22

how does the Glossopharyngeal (CN IX) and vagus (CN X) emerge from brain

Answer 22

Glossopharyngeal + vagus nerve emerges from lateral surface of medulla oblongata;
Both exit skull via jugular foramen

Question 23

where does the spinal accessory nerve (CN XI) emerge from

Answer 23

Spinal accessory (CN XI)
Emerges from first 5-6 cervical segments of spine then runs superiorly through foramen magnum and leaves skull via jugular foramen with glossopharyngeal and vagus (CN IX and X)

Question 24

where does the hypoglossal nerve (CN XII) emerge from

Answer 24

the hypoglossal nerve emerges from anterior medulla oblongata then runs through hypoglossal canal