Lecture 26 RH Flashcards
How many bones does the skull have?
22 bones
What are joints between skull bones called? Are they mobile?
Sutures, they are immobile
What are the 3 major parts of the skull?
Cranium: covers the brain.
Facial bones
Mandible
What is contained within the cranial cavity?
Cranial cavity contains brain, meninges, cranial nerves, arteries, veins, venous sinuses.
What is the roof of the cranium called?
Roof of cranium is called the cranial vault.
What is the floor of the cranium called?
Floor of cranium is called the cranial base.
What are the names of the cranial bones?
Bones are named after the lobes of the brain.
Parietal x2
Occipital x1
Temporal x2
Sphenoid x1
Ethomoid x1
Frontal x2
What is the maxilla bone? How many are there?
Maxilla are the upper jaw bones. There are 2 of them.
What are the zygomatic bones? How many does the skull contain?
zygomatic bones are on the lateral aspects of the eye socket they are colloquially known as cheek bones.
What are the facial bones called?
maxilla x2
Nasal bones x2
Lacrimal bones x2
Vomer x1
Palatine bones x2
Inferior Conchae x2
Mandible x1
What is the mandible?
Mandible is the lower jaw bone.
Where are lacrimal bones found? How many of them are there?
Lacrimal bones are found within the orbit. 2 of these bones exist
What suture is found between the parietal bones?
The 2 parietal bones are joined by the sagittal suture.
What suture combines the 2 parietal bones with the frontal bone?
2 parietal bones joing with frontal bone via coronal suture.
How are the parietal bones joined to the occipital bone?
2 parietal bones are joined with occipital bone by the lambdoidal suture
What are the levels of the floor of the cranium? How are these levels arranged?
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa
These levels are arranged like a staircase.
What are the bones that make up the anterior cranial fossa?
Frontal bone
Floor of the anterior cranal fossa contains the orbital plates of frontal bone and cribiform plate of the ethmoid bone.
posterior part of the anterior cranial fossa is dominated by the sphenoid bone.
Where does the anterior cranial fossa end?
Sphenoid bone looks like a butterfly with wings. Anterior cranal fossa ends at the lesser wing.
What are the plates that cover the orbit of the eye called?
Plates that covers the orbit of the eyes are the orbital plates.
What is the function of the holes in the ethmoid bone?
ethmoid contains holes through which nerves of cranial cavity pass
What are the bones that make up the middle cranial fossa?
Anteriorly: Lesser wing of the sphenoid
Posteriorly: Petrous portion of the temporal bone
Laterally: Temporal bone, greater wing of the sphenoid bone, parietal bone
Why is there a gap between the greater and lesser wings of the sphenoid bone?
gap between lesser and greater wing of the sphenoid is important for passage of blood vessels and nerves.
What is the function of the middle part of the sphenoid bone?
Middle part of the sphenoid is the location of important brain structures (eg pituitary gland) it is also called “the turkish saddle”.
What are the bones that make up the posterior cranial fossa?
Anteriorly: petrous portion of the temporal bone
Floor: Basilar, condylar, and squamous portions of the occipital bone, mastoid process of the temporal bone.
Posteriorly the occipital bone
What are the structures contained within the posterior cranial fossa?
Cerebellum
pons
medulla oblongata
How many cranial nerves are there?
12 paired nerves and they are all connected to the brain.
What is the general function of the cranial nerves?
Supply somatic and visceral motor and sensory information to the head.
What is the function of cranial nerves IX and X?
visceral sensory and motor innervation to the neck, chest and abdomen.
How are cranial nerves arranged and named?
Cranial nerves are arranged in pairs and are named from 1 to 12 according to their target organ. 1 is rostral and 12 is very caudal.
Where do cranial nerves come from?
Most cranial nerves originate from the brainstem.
1 and 2 originate from within the rest of the brain.
What is the function of the brain stem?
Brain stem is important for survival but also contains nuclei for cranial nerves 3 - 12.
Cranial nerve 1:
olfactory
Cranial nerve 2:
optic
Cranial nerve 3:
oculomotor
Cranial nerve 4:
Trochlear
Cranial nerve 5:
Trigeminal
Cranial nerve 6:
Abducent
Cranial nerve 7:
Facial
Cranial nerve 8:
Vestibulocochlear
Cranial nerve 9:
Glossopharyngeal
Cranial nerve 10:
Vagus
Cranial nerve 11:
Accessory
Cranial nerve 12:
Hypoglossal
What is the principle regarding cranial nerves and ipsilateral structures?
most cranial nerves are associated with an ipsilateral structure.
Which cranial nerves are purely sensory?
CN1 (olfactory), CN2 (optic), CN8 (vestibulocochlear)
Which cranial nerves are purely motor?
CN3 (oculomotor), CN4 (trochlear), CN6 (abducent), CN11 (accessory)
Which cranial nerves are mixed sensory and motor? Why are they mixed?
CN5 (trigeminal), CN7 (facial), CN9 (glossopharyngeal), CN10 (vagus)
They are mixed because they have multiple functions due to each cranial nerve having many functional groups of fibers.
Where does the olfactory nerve exit the skull and what does it do?
Olfactory nerve exits through the cribiform plate and is responsible for smelling things.
Where does the optic nerve exit the skull and what does it do?
It is responsible for vision and exits the skull from the optic canal.
Does the innervation of the eye come from one optic nerve?
No, each eye gets innervation from both cranial nerves of the pair (CN2) equally
How many extraocular muscles are there?
6; 4 rectus and 2 oblique
What are the types of rectus extraocular muscles?
superior rectus
medial rectus
lateral rectus
inferior rectus
What are the types of oblique extraocular muscles?
superior oblique
inferior oblique
What cranial nerves innervate the extraoccular muscles?
cranial nerve 3 (oculomotor): it innervates 4 of the muscles.
Cranial nerve 4 (trochlear)
Cranial nerve 6 (abducent)
Where do cranial nerves 3 (oculomotor), 4(trochlear), and 6 (abducent) exit the skull to go to the eyes?
superior orbital fissure between greater and lesser wing of the sphenoid bone.
How does the optic nerve go from the brain to the eye?
optic nerve goes through the optic canal
What does CN5 (trigeminal) do?
Important for sensation in the anterior face and is important for mastication.
*Behind the ear is controlled by a spinal nerve.
Where does CN5 (trigeminal nerve) exit the skull?
V1 exits from the superior orbital fissure.
V2 exits from foramen rotundum
V3 exits from foramen ovale.
What does the facial nerve (CN7) do?
It controls muscles of facial expression.
It is important for control of viscera in some parts of the head such as the lacrimal gland and the sublingual gland.
It provides taste sensation to anterior 2/3rds of the face
It provides somatic sensory innervation
Where does the facial nerve exit the skull?
Internal acoustic meatus
What are the terminal branches of the facial nerve?
Temporal branch for the forehead.
Zygomatic
Buccal
Cervical
Marginal mandibular
What is the function of the vestibulocochlear nerve (CN8)?
Hearing and balance
Where does the vestibulocochlear nerve exit the skull?
Internal acoustic meatus
What is the function of the glossopharyngeal nerve?
Important for sensory innervation of the tongue (posterior 1/3), pharynx, middle ear, and carotid body.
Visceral motor: parasympathetic autonomic innervation to parotid.
Motor to the stylopharyngeus
Where does the glossopharyngeal nerve (CN9) exit the skull?
Via the jugular foramen
What does the Vagus nerve (CN10) do?
It is the most important autonomic nerve.
It is motor to muscles of soft palate, pharynx, larynx, upper oesophagus, and 1 tongue muscle.
It has functions for taste and general baroreceptors
Where does the vagus nerve exit the skull?
Jugular foramen
What is the function of the spinal accessory nerve?
Shrugs shoulders and turns head. (innervates sternomastoid and upper trapezius)
Where does the spinal accessory nerve exit the skull?
Upper 5 - 6 of cervical spinal cord. Nerve enters cranium via foramen magnum then travels with X roots and exits jugular foramen.
What is the function of the hypoglossal nerve (CN12)?
It innervates all tongue muscles but 1.
Where does the hypoglossal nerve exit the skull?
hypoglossal foramen.
