Lecture 16 - Skull and Brain

Question 1

Function of brachial arches in early vertebrates

Answer 1

Provide support for the gills

Question 2

Origin of the jaws in early fishes

Answer 2

jaws = 1st brachial arch, 2nd brachial arch connects jaws to head

Question 3

Evolution path of brachial arches

Answer 3

Brachial arch structures (early vertebrates) = Jaws (fishes) = Ear ossicles (mammals)

Question 4

Brachial arch evolution to mammalian structures

Answer 4

Brachial arch 1 = part of lower jaw, malleus and incus. Brachial arch 2 = stapes, body of hyoid, styloid ligament. Brachial arch 3 = body of hyoid Brachial arch 4 = thyroid and cricoid cartilage

Question 5

Brain evolution

Answer 5

Brain and cranial nerve organization dates back to cartilagenous fishes (our inner sharks)

Question 6

Changes between mammalian brains and other animal brains

Answer 6

Larger forebrain Smaller midbrain and hindbrain

Question 7

Skull

Answer 7

Cranium + Mandible

Question 8

Jaws

Answer 8

Part of maxillary bone, mandible + teeth

Question 9

Viscerocranium

Answer 9

face + jaws -formed by intramembranous ossification

Question 10

Basicranium

Answer 10

skull base -formed by endochondral ossification

Question 11

Neurocranium

Answer 11

cranial vault/brain case -formed by intramembranous ossification

Question 12

Endochondral Bone Formation

Answer 12

Question 13

Bones of the basicranium (skull base)

Answer 13

Frontal, ethmoid, sphenoid, temporal, occipital

Question 14

What bone does the brain sit on?

Answer 14

Brain sits on cribiform plate of the ethmoid bone

Question 15

Function of holes on cribiform plate

Answer 15

Passage of olfactory nerves into the nose (smell)

Question 16

Sella turcica

Answer 16

Houses the pituitary gland

Part of the sphenoid bone (butterfly shaped bone)

Question 17

2 parts of temporal bone

Answer 17

Squamous (flat) portion

Petrol (houses ear structures) portion

Question 18

Foramen Magnum

Answer 18

Large hole on occipital bone where the spinal cord passes through

Question 19

Cranial Fossae

Answer 19

Question 20

Example of adult skull bones having both endochondral and intramembranous components

Answer 20

Petrosal portion of temporal bones = Endochondral

Squamous portion of temporal bones = Intramembranous

Question 21

Intramembranous Bone Formation

Answer 21

Question 22

Bones of the neurocranium (cranial vault)

Answer 22

Frontal, ethmoid, sphenoid, temporal (2), occipital, PARIETAL (2)

*same as basicranium, plus parietal bones

Question 23

After the bones are formed, how does the skull grow?

Answer 23

1. Sutural growth
2. Drift
3. Synchondrosis growth

Question 24

Sutural Growth

Answer 24

• developing organ pushes bones apart at sutures
• osteoblasts fill open area
• driven by intracranial pressure

Question 25

Major cranial sutures

Answer 25

Question 26

Drift

Answer 26

- Coordinated deposition (+) and resorption (-) - Can move bones and expand cavities

Question 27

Synchondrosis Growth

Answer 27

Elongation of cranial base at three growth plates

Question 28

Purpose of fontanelles and sutures

Answer 28

- accomadate rapid brain growth - allows for passage through birth canal (temporary deformation of the skull during birth)

Question 29

Brain Folds (gyri and sulci)

Answer 29

- Increase brain surface area - Allow for more neurons in smaller space

Question 30

Gray matter in the brain

Answer 30

- neuronal cell bodies - located in outer regionsof the brain

Question 31

White matter in the brain

Answer 31

- axons - deeper regions of the brain

Question 32

Which brain structures comprise the hindbrain?

Answer 32

Pons, medulla oblongata, cerebellum

Question 33

Cerebellum

Answer 33

Function: gross motor coordination (posture, balance, speech) -many small, densely packed neurons

Question 34

Pons

Answer 34

Function: aids in physiological functions, wakefullness, and alertness

Question 35

Medulla Oblongata

Answer 35

Function: controls autonomic functions (breathing, heartrate, blood pressure, sneezing, coughing)

Question 36

Midbrain

Answer 36

small in mammals, coordinates body movements with forebrain, involved in motivation (reward, addiction), involved with eye movements

Question 37

Which brain structures comprise the forebrain?

Answer 37

thalmus, hypothalmus, cerebrum

Question 38

Thalmus

Answer 38

- relays sensory info to cerebrum - involved in awareness and learning

Question 39

Hypothalmus

Answer 39

- controls release of pituitary hormones - involved in physiological processes (thirst, hunger, temperature regulation)

Question 40

Cerebrum

Answer 40

- 4 lobes (frontal, parietal, occipital, temporal) - receives/processes sensory information - complex cognitive processes (language, thinking, consciousness, memory) - regional specialization

Question 41

Frontal Lobe Function

Answer 41

- motor functions - memory - emotional regulation - motor aspects of speech

Question 42

Parietal Lobe Functions

Answer 42

- integrate sensory stimuli (vision and balance) - major speech areas

Question 43

Temporal Lobe Functions

Answer 43

- receives sensory input from ears - smell - visual/word memory

Question 44

Occipital Lobe Function

Answer 44

-vision (receives sensory input from eyes)

Question 45

Corpus Callosum

Answer 45

- think bundle myelinated axons - connects right and left cerebral hemispheres

Question 46

Central Sulcus

Answer 46

- separates frontal and parietal lobes - pre and post central gyri

Question 47

Pre-central Gyri

Answer 47

Primary Motor Cortex: coordinate all voluntary skeletal muscle movement

Question 48

Post-central Gyri

Answer 48

Primary Sensory Cortex: receives sensory information from body