Lecture 19

Question 1

How many bones are in the skull and how many cranium, facial, and ear bones are there?

Answer 1

Skull - 28 bones in total

Cranium bones - 7
Facial bones - 14
Ear bones - 6

Question 2

How many bones are in the vertebral column and how many are in each the cervical, thoracic, lumbar, sacrum, and coccygeal levels?

Answer 2

Vertebral column - 26 bones

Cervical vertebrae - 7 
Thoracic vertebrae - 12
Lumbar vertebrae - 5
Sacrum - (5 fused vertebrae)
Coccygeal - (4/5 fused vertebrae)

Question 3

What bones make up the skull?

Answer 3

Cranium vault + facial skeleton.

Question 4

How many bones is the cranium composed of?

Answer 4

8 bones

7 visible on lateral sides

1 visible internally - Ethmoid bone (don’t need to know about)

Question 5

What are the 7 bones of the cranium that are visible on the lateral sides and roughly where are they located?

Answer 5

• Frontal bone (1) - front of the cranium
• Pariental bone (2) - mid-top part of the cranium
• Occipital bone (1) - back of the cranium
• Temporal bone (2) - lower part of the cranium
• Sphenoid bone (1) - on the sides of the cranium near the eye socket.

Question 6

What are the 3 cranial sutures on the lateral view of the cranium and what flat bones do they connect?

Answer 6

• Coronal suture - connects the Frontal bone to the Parietal bone
• Lambdoidal suture - connects the Parietal bone to the Occipital bone
• Squamous suture - connects the Temporal bone to the Parietal bone.

Question 7

Why are the cranial sutures not fully closed yet at birth and what are the gaps of soft tissue called?

Answer 7

The cranial sutures are not fully closed yet at birth to allow for the brain to develop and for the cranium to expand along side the brain.

The gaps of soft tissue are called fontanelles.

Question 8

What are the consequences if the sutures close prematurely?

Answer 8

Block brain growth, and causes cognitive impairment e.g. seizures - caused by the brain pushing against the cranium.

Question 9

How many bones is the facial skeleton composed of and what are the different bones? (anterior view)

Answer 9

Facial skeleton - 14 bones (7 externally visible)

Zygomatic bone - (2) - ‘cheek bones’ located near the eye socket

Maxillary bone - (2) - located around the nose in the ‘cheek’ region

Mandible bone - (1) - ‘jaw bone’

Nasal bone - (2) - top part of the nose

7 internally visible bones - don’t need to know.

Question 10

What is the meninges and how many components are there?

Answer 10

The meninges are composed of 3 layers and protect the brain.
Located between the skull and brain.

Question 11

What are the 3 layers of the meninges called?

Answer 11

• Dura Mater (outer layer)
• Arachnoid (middle layer)
• Pia Mater (inner layer)

Question 12

What are some features of the Dura Mater layer?

Answer 12

• Outer most layer
• Dense and Fibrous - tough - prevents sharp fractured bone pieces from reaching the brain.
• 2 layers - inner layer forms the dural reflection
• Space between the layers forms the venous sinuses

Question 13

What is the dural reflections and what are its features?

Answer 13

• Formed by the inner layer of dura mater
• Separates the major divisions of the brain
• 3 of them

Question 14

What are the 3 dural reflections called and what do regions do they seperate?

Answer 14

1. Falx cerebri
   - separates cerebral hemispheres
   - median plane
2. Falx cerebelli
   - Separates cerebellar hemispheres
   - median plane
3. Tentorium cerebelli
   - separates the cerebrum from the cerebellum
   - horizontal plane

Question 15

What is the Venous sinus and what does it do?

Answer 15

• Formed between the 2 layers of dura mater

- Allows for Venous drainage from the brain

Question 16

What is the arachnoid mater and what are its features?

Answer 16

• Layer beneath the dura mater
• held up by ‘spider leg’ like structures which allows for blood vessels to fit inside.
• Space formed by the ‘spider leg’ like structures between the arachnoid and Pia mater is filled with Cerebrospinal fluid (CSF) and blood vessels.

Question 17

What are the Arachnoid granulations (villi)?

Answer 17

• ‘pumps’ that penetrate through the dura into the Venous sinus and pump old CSF from the subarachnoid space into the venous sinus.

Question 18

What is the Pia mater and what are its features?

Answer 18

• Transparent and delicate layer covering the brain
• Blood vessels from the subarachnoid space sit on top of the Pia mater
• Has sulci (dips in the white matter of the brain)

Question 19

What are the membrane layers of the spinal cord?

Answer 19

• The same as the cranial vault membrane.
• Dura mater (outer layer)
• Arachnoid mater (middle layer)
• Pia mater (inner layer)

Question 20

What is the role of CSF?

Answer 20

Nourishes and protects the brain.

Question 21

What are the components of The Ventricular System? (anterior view)

Answer 21

• Lateral ventricle (space filled with CSF)
• Interventricular foramen
• Third ventricle (space filled with CSF)
• Cerebral aqueduct (connects the 3rd ventricle to the 4th ventricle)
• Fourth ventricle (space filled with CSF)
• Lateral apertures (side branches, which CSF can exit through)
• Central canal (going down into the spinal cord, where CSF can exit through)

Question 22

What produces the CSF and where is it located?

Answer 22

CSF is produced by the choroid plexus, which lines the inside of the ventricles.

Question 23

What is the circulation route of CSF?

Answer 23

Circulates through ventricles and
subarachnoid space of the brain
and spinal cord

Route:

Lateral ventricle —> 3rd ventricle —> cerebral aqueduct —> 4th ventricle —> subarachnoid space

Enter the venous blood circulation within the venous sinuses via the arachnoid villi/granulations (pumps).

Question 24

What problems can occur if the ventricles are abnormally large? (blocked aqueduct)

Answer 24

• Hydrocephalus
• increased intracranial pressure
• symptoms could includes: convulsion, tunnel vision, seizures, mental disabilities etc.

Question 25

What does CSF stand for.

Answer 25

Cerebrospinal Fluid.