L9.2 Skll and cranial nerve

Question 1

Features of the skull bones

Answer 1

• Skull has 22 bones united at immobile joints call Sutures, grouped into
  
  • Cranium
  • Facial bones (Hangs off cranium)
  • Mandible

Question 2

What is the roof and floor of the cranial cavity called?

Answer 2

• Roof = Cranial vault
• Floor = Cranial base

Question 3

Bones of the cranium (9)

Answer 3

• Frontal x2 (technically 1 bone, but suture separates it into 2)
• Parietal x2 (Green)
• Occipital x1 (Blue back part)
• Temporal x 2 (Orange - contain apparatus allowing us to hear)
• Sphenoid x 1 (Red)
• Ethomoid x 1 (Base of the frontal bone)

Question 4

Facial bones (14)

Answer 4

• Maxilla (purple) x2
• Zygomatic bone (orange) - forms the cheek bones x2
• Orbit bones: (inside the eye)
  
  • Nasal bones x2
  • Lacrimal bones x2
  • Vomer x1
  • Palatine bones x2
  • INF conchae x2
• Mandible

Question 5

Different skull sutures

Answer 5

• Sagittal suture - down middle of skull
• Coronal suture - 2 parietal bones joins frontal bone
• Lambdoidal suture - joins 2 parietal bone with occipital bone

Question 6

Diagram of the Floor of the cranium

Answer 6

Question 7

ANT cranial fossa

Answer 7

• ANT- Frontal bone
• POS - Lesser wing of sphenoid (top wing)
• Floor
  
  • Orbital plates of the frontal bone
  • Cribiform plate of the ethmoid

Question 8

Middle cranial fossa

Answer 8

• ANT - Lesser wing of sphenoid
• POS - Petrous portion of temporal bone
• LAT
  
  • Temporal bone
  • Greater win of sphenoid
  • Parietal bone

Question 9

POS cranial fossa

Answer 9

• Contents:
  
  • Cerebellum
  • Pons
  • Medulla oblongata
• ANT - Petrous portion of the temporal bone
• Floor
  
  • Basilar, condylar, squamour portions of the occipital bone
  • Mastoid process of the temporal bone

Question 10

Features of the sphenoid bone

Answer 10

• Forms ANT and middle cranial fossa
• Connects orbits with cranial cavity
• Has a gap → allows V,A,N to travael through

Question 11

General features of the cranial nerves

Answer 11

• 12 paired nerves, somatic/visceral motor and sensory information to head
• Most cranial N originate from the brainstem
  
  • Associated with cranial N 3-12 (1&2 found in CNS)
  • Cranial N pass raustral to caudal (3 is above 4…)
  • Cranial N 4 goes out in dorsal aspect

Question 12

1 - olfactory nerve

Answer 12

• Action: sense of smell
• Exit: Cribiform plate
• N → bulb → tract → brain

Question 13

2 - optic nerve

Answer 13

• Action: Vision
• Exit: Optic canal in sphenoid bone

Question 14

3 - Oculomotor

4 - Trochlear

6 - Abducent

Answer 14

• Nerves of ocular motion:
• Six extraocular muscles (controlled by 3 nerves)
• Action: Act in a coordinated fashion to move eyeball around
• Exit: Through superior orbital fissure (b/w lesser and greater wing of sphenoid)

Question 15

5 - trigeminal nerve

Answer 15

• Somatic sensory to face (major)
• ANT side of face - up to mid
• Motor to muscles of mastication

3 major branch exits

• V1 → Superior orbital fissure
  
  • Opthalic division
• V2 → Foramen rotundum
  
  • Maxillary division (Jaw to cheek area)
• V3 → Foramen ovale
  
  • Mandibular division

Question 16

7 - facial nerve

Answer 16

• Action:
  
  • Motor: Muscles of facial expression
  • Visceral efferent (PS): Glands (lacrimal, sublingual glands)
  • Visceral sensory (Taste to ANT 2/3 of tongue)
  • Somatic sensory
• Exits: Internal acoustic meatus

Question 17

Muscles of the face

Answer 17

• Temporal
  
  • Raising eyebrow and closing eyelid
• Zygomatic
  
  • Cheeks
• Buccal
  
  • Smiling
• Marginal mandibular
  
  • Moves jaw
• Cervical

Question 18

8 - Vestibulocochlear

Answer 18

• Action: Hearing and balance (sensory)
• Exit: Internal acoustic meatus
  
  • Petrus portion of the temporal bone

Question 19

9 - Glossopharyngeal N

Answer 19

• Action: (mostly sensory)
  
  • Sensory from tongue (POS 1/3), pharynx, middle ear and carotid body
  • Taste: POS 1/3 tongue
  • Visceral motor: PNS to parotid
  • Motor: Stylopharyngeus
• Exit: Jugular formen

Question 20

10 - vagus

Answer 20

• Action: (THE autonomic nerve)
  
  • Visceral motor: Mostly autonomic
  • Motor to muscles around pharynx & larynx
  • Sensory: taste, pharynx, larynx, baro-receptors
• Exit: Jugular foramen

Question 21

11 - spinal accessory N

Answer 21

• Action: Motor to sternomastoid and upper part of trapezius
• Exit: Spinal accessory nucleus in the upper 5-6 cervical spinal cord
  
  • N enter cranium via foramen ovale

Question 22

12 - hypoglossal N

Answer 22

• Motor: muscles of the tongue
• Exit: Hypoglossal foramen
  
  • Tongue points towards the direction of defective hypoglossal branch side