Brain and Cranial - Lab

Question 1

5

Answer 1

meningeal layer of dura matter.

Dura mater is the tough, outermost meningeal layer that protects the brain and spinal cord.

It has two layers in the brain:

Periosteal layer: Outer layer; adheres to the inner surface of the skull. It acts like the skull’s inner periosteum and doesn’t extend into the spinal cord.

Meningeal layer: Inner layer; lies closer to the brain. It follows the contours of the brain and continues down the spinal cord as the spinal dura mater.

Function: Provides a durable protective barrier, supports venous sinuses (where layers separate), and helps anchor the brain in place.

Question 2

Answer 2

superior sagittal sinus
- Location: Located in the superior margin of the falx cerebri, between the periosteal and meningeal layers of the dura mater.

• Formed by: Separation of the periosteal and meningeal layers of the dura mater.
• Function: Re-absorption cerebrospinal fluid (CSF) via arachnoid granulations and venous blood from superior cerebral veins; drains to jugular vein

Question 3

Answer 3

inferior sagittal sinus

• Location: Runs along the inferior margin of the falx cerebri, superior to the corpus callosum, within the meningeal layer of the dura mater
• Formed by: A dural venous channel within the meningeal layer of the dura mater.
• Function: Receives venous blood from deep and medial cerebral veins; drains into the straight sinus, eventually reaching the jugular vein.

arachnoid granulations are not present along the inferior margin of the falx cerebri, where the inferior sagittal sinus is located.

Question 4

Answer 4

Falx Cerebri

• Location: Vertical, crescent-shaped fold of the meningeal layer of the dura mater located in the longitudinal fissure between the two cerebral hemispheres.
• Formed by: Infolding of the meningeal layer of the dura mater; contains the superior sagittal sinus (in its superior margin) and inferior sagittal sinus (in its inferior margin).
• Function: Separates the cerebral hemispheres and stabilizes the brain within the cranial cavity; supports venous sinuses that drain blood and CSF to the jugular vein.

Question 5

Answer 5

Tentorium cerebelli

• Location: Horizontal fold of the meningeal layer of the dura mater between the occipital lobes and the cerebellum; forms the roof of the posterior cranial fossa.
• Formed by: Infolding of the meningeal layer of the dura mater; contains the transverse sinuses (along its posterior and lateral margins) and the straight sinus (along its midline junction with the falx cerebri).
• Function: Separates the cerebrum from the cerebellum; supports occipital lobes and encloses venous sinuses that ultimately drain to the jugular vein.

Question 6

Answer 6

Falx Cerebelli

• Location: Small vertical fold of the meningeal layer of the dura mater in the posterior cranial fossa, between the two hemispheres of the cerebellum.
• Formed by: Infolding of the meningeal layer of the dura mater; sometimes contains the occipital sinus along its posterior margin.
• Function: Partially separates the cerebellar hemispheres and may support venous drainage via the occipital sinus to the jugular vein.

Question 7

Answer 7

Arachnoid villa / Arachnoid granulations
- Location: Small protrusions of the arachnoid mater that extend through the meningeal layer of the dura mater into the dural venous sinuses, especially the superior sagittal sinus.

• Formed by: Outpocketings of arachnoid mater penetrating the dura. Clusters of villi form arachnoid granulations.
• Function: Allow cerebrospinal fluid (CSF) to pass from the subarachnoid space into the venous blood of the dural venous sinuses; contribute to CSF reabsorption and drainage to the jugular vein.

Question 8

Answer 8

choroid plexus
- Location: Found in the walls of the lateral, third, and fourth ventricles of the brain.

• Formed by: Invaginations of pia mater containing fenestrated capillaries, covered by ependymal cells specialized for secretion.
• Function: Produces cerebrospinal fluid (CSF) by filtering plasma from blood; CSF flows through the ventricular system and into the subarachnoid space, eventually draining into the venous system via arachnoid granulations.

choroid plexus of lateral ventricles

Question 9

Answer 9

Lateral ventricles

• Location:
  Within the cerebral hemispheres; one in each hemisphere.
  Extend through the frontal, parietal, occipital, and temporal lobes.
• Formed by:
  Roof: Corpus callosum (body and splenium)
  Floor: Anterior (frontal) horn → Frontal lobe, Body → Parietal lobe, Posterior horn → Occipital lobe, Inferior horn → Temporal lobe
  Medial wall: Septum pellucidum (separates left and right ventricles)
  Lateral wall: Caudate nucleus (body)
• Function: Contain and circulate cerebrospinal fluid (CSF). Provide cushioning and support for brain structures. Contribute to CSF flow through the interventricular foramina to the third ventricle

empty space between the corpus callosum

Question 10

Answer 10

Interventricular foramen

-Location:
Connects each lateral ventricle to the third ventricle.
Located inferior to the fornix and anterior to the thalamus, near the midline of the brain.

-Function:
Allows cerebrospinal fluid (CSF) to flow from each lateral ventricle into the third ventricle, maintaining proper circulation through the ventricular system.

There are two interventricular foramina — one on each side. Each connects a lateral ventricle to the third ventricle.

Question 11

Answer 11

Third Ventricle

• Location:
  A narrow, midline cavity located in the diencephalon, between the left and right thalami.
  The hypothalamus forms its floor, and the epithalamus (including the pineal gland) forms part of its roof.
• Function:
  Contains cerebrospinal fluid (CSF) and serves as a central passageway between the lateral ventricles (via the interventricular foramina) and the fourth ventricle (via the cerebral aqueduct).
  Helps circulate and distribute CSF through the brain’s ventricular system.

hole in third ventricle is the interthalamic adhesion

in image, thalamus encloses third ventricle - blue

Question 12

Answer 12

Cerebral aqueduct

• Location:
  Midbrain; connects third ventricle to fourth ventricle
• Function:
  Carries CSF from third to fourth ventricle

Question 13

Answer 13

Fourth Ventricle

• Location:
  Hindbrain, between the pons and medulla (anteriorly) and the cerebellum (posteriorly)
• Function:
  Holds CSF, connects to cerebral aqueduct (above) and central canal (below); CSF exits via median aperture and lateral aperture to subarachnoid space to bath brain

Question 14

Answer 14

arachnoid villi

• Location:
  Projections of the arachnoid mater into the dural venous sinuses, especially the superior sagittal sinus
• Function:
  Reabsorb cerebrospinal fluid (CSF) into the venous blood system via pressure-dependent flow

Question 15

structure E

Answer 15

Medulla Oblongata

• Relays sensory and motor signals between the brain and spinal cord
• Controls vital autonomic functions: heart rate, blood pressure, and respiration
• Coordinates reflexes such as coughing, swallowing, and vomiting
• Contains nuclei for cranial nerves 9 - 12 (glossopharyngeal, vagus, accessory, hypoglossal)
• Site of pyramidal decussation (crossing of motor tracts) - anterior / ventral aspect

hypothalamus “master” regulator of autonomic functions, medulla oblongata direct control of vital autonomic functions

Question 16

structure 22

Answer 16

Decussation of pyramids
part of medulla oblongata

• Location:
  Inferior medulla oblongata, at the junction with the spinal cord
• Function:
  Site where motor fibers of the corticospinal tract cross to the opposite side, enabling contralateral control of voluntary movement

The corticospinal tract carries motor commands from the cerebral cortex down to the spinal cord. -> descending, first order

Question 17

structure D

Answer 17

Pons
Relays signals between the cerebrum, cerebellum, and spinal cord

Contains ascending sensory and descending motor tracts

Houses nuclei for cranial nerves 5 - 8 (Trigeminal, Abducens, Facial, Vestibulocochlear)

Helps regulate breathing rhythm with the medulla oblongata

structure a

Question 18

structure C

Answer 18

Midbrain / Mesencephalon

Coordinates visual and auditory reflexes via corpora quadrigemina (superior and inferior colliculi)

Passes ascending sensory (second-order) and descending (first-order) motor pathways through cerebral peduncles

Question 19

Answer 19

Cerebral Peduncles
part of midbrain

Contain descending motor tracts (e.g., corticospinal, corticobulbar) from the cerebral cortex

Transmit voluntary motor commands to the brainstem and spinal cord

The motor tracts run from the cerebral cortex, pass through the cerebral peduncles, and eventually reach the decussation of the pyramids in the medulla.

number 15

Question 20

Answer 20

Corpora Quadrigemina
part of midbrain

Superior Colliculi
Coordinate visual reflexes (e.g., tracking moving objects, pupillary reflex)
Integrate visual input with head, neck, and eye movements

Inferior Colliculi
Process and relay auditory information to the thalamus
Involved in auditory reflexes (e.g., turning head toward a sound)

Question 21

Answer 21

thalamus
part of diencephalon

• Processes sensory infomration and relays to appropriate location in cerebrum
• Relays motor information from the cerebellum and basal nuclei (think substantia nigra) to the motor cortex -> fine tune / regulation of movement
• Involved in emotion and memory via connections with the limbic system

Question 22

brown dot

Answer 22

intermediate mass
part of thalamus

Joins the left and right thalami across the third ventricle

Mostly structural; has no significant functional role in signal transmission

Absent in ~20–30% of people without clinical effect, absence associated with schizophrenia

Question 23

area g

Answer 23

hypothalamus
part of diencephalon

• Regulates autonomic functions: heart rate, blood pressure, digestion, temperature
• Subconscious control of skeletal muscles
• synthesizes oxytocin and ADH (also called vasopressin)
• Emotional, behavioral, and thirst drives
• coordination between voluntary and autonomic functions
• circadian rhthym -> master clock -> sends signlas to epithalamus / pineal gland

model guide states g is the third ventricle - hypothalamus forms part of walls and floor

Question 24

Answer 24

Pituitary Gland

Known as the “master gland” of the endocrine system

Anterior pituitary: secretes hormones regulating growth, thyroid, adrenal glands, reproduction (e.g., GH, ACTH, TSH, LH, FSH, prolactin)

Posterior pituitary: releases hormones made by the hypothalamus (e.g., oxytocin, ADH)

Controlled by the hypothalamus via hormonal and neural signals

la glándula pituitaria

Question 25

Answer 25

**Mammillary Bodies** Location: Part of the hypothalamus, located on the underside of the brain, posterior to the pituitary gland and anterior to the midbrain. Function: - Involved in **memory** processing; receive input from the hippocampus via the fornix and relay it to the thalamus - Important in the limbic system, especially for recollective memory.

Question 26

Answer 26

**Epithalamus** *el epitálamo* - Regulates circadian rhythms and emotional responses - Connects limbic system to other brain regions **pineal Gland** *la glándula pineal* - Produces melatonin in response to darkness - Regulates sleep-wake cycles (biological clock) -> recieves signals from hypothalamus (master clock) - Light exposure inhibits melatonin production *Posterior epithalamus*

Question 27

Answer 27

**Vermis** *part of cerebellum* coordinating body posture, locomotion, and maintaining balance, particularly for the head and trunk, and also contributes to motor learning and some emotional regulation.

Question 28

Answer 28

**Arbor Vitae** - Transmits sensory and motor information between the cerebellar cortex and deep cerebellar nuclei - Coordinates fine-tuned motor activity, balance, and posture - Acts as the white matter core of the cerebellum, surrounded by gray matter (cortex) *The cerebellum acts like the brain’s quality control center for movement — making sure your actions are smooth, coordinated, and adjusted in real time.*

Question 29

Answer 29

**Longitudinal fissure** *cisura longitudinal del cerebro* Separates the left and right cerebral hemispheres; allows each hemisphere to function semi-independently while still connected by the corpus callosum

Question 30

Answer 30

**Transverse fissure** *cisura transversa del cerebro* Separates the cerebrum from the cerebellum; allows passage of the tentorium cerebelli (a dural fold that supports the occipital lobes)

Question 31

*structures 1, 2 & 3*

Answer 31

**precentral gyrus** *El giro precentral* Location: Anterior to the central sulcus, in the frontal lobe Function: Primary motor cortex — controls voluntary movements of the contralateral body **central Sulcus** *el surco central* Location: Groove separating the frontal lobe (anterior) from the parietal lobe (posterior) Function: Divides motor cortex (precentral gyrus) from sensory cortex (postcentral gyrus) **postcentral Gyrus** *el giro postcentral* Location: Posterior to the central sulcus, in the parietal lobe Function: Primary somatosensory cortex — processes touch, pressure, pain, and proprioception

Question 32

Answer 32

**corpus callosum** *el cuerpo calloso* - Location: Deep within the longitudinal fissure, forming the roof of the lateral ventricles; connects the left and right cerebral hemispheres - Function: Facilitates communication between hemispheres by transmitting motor, sensory, and cognitive information

Question 33

Answer 33

**Septum Pellucidum** *el septum pellucidum / el tabique pelúcido* - Location: Thin vertical membrane between the lateral ventricles, located beneath the corpus callosum and above the fornix - Function: Separates the body of the left and right lateral ventricles; provides structural partitioning, though it has no known major functional role

Question 34

Answer 34

**Basal Nuclei** *Los núcleos basales / Los ganglios basales* - Location: Deep within the cerebral hemispheres, surrounding the thalamus; major components include the caudate nucleus, putamen, and globus pallidus - Function: Regulate voluntary motor control, muscle tone, habit learning, and movement initiation by interacting with the motor cortex and other brain areas

Question 35

Answer 35

**Fornix** *el fórnix* - Location: Arch-shaped white matter tract beneath the corpus callosum and above the thalamus; connects the hippocampus to the mammillary bodies - Function: Transmits limbic system signals, especially those related to memory, from the hippocampus to the mammillary bodies of hypothalamus

Question 36

Name and Location of Lobes

Answer 36

**Frontal Lobe** *el lóbulo frontal* Controls voluntary movement, decision-making, planning, personality, and speech production (Broca’s area) **Parietal Lobe** *el lóbulo parietal* Processes somatosensory information (touch, pressure, pain, temperature) and spatial awareness **Temporal Lobe** *el lóbulo temporal* Responsible for hearing, language comprehension (Wernicke’s area), and memory **Occipital Lobe** *el lóbulo occipital* Processes visual information

Question 37

Answer 37

**Pyramidal cells cerebrum** *Pyramid-shaped soma with long apical dendrite* - Found in the cerebral cortex, especially in the precentral gyrus (motor cortex) - Function as primary output neurons of the cortex - Send long axons to the brainstem and spinal cord (e.g., corticospinal tract) - Involved in voluntary motor control, cognition, and decision-making

Question 38

Answer 38

**Purkinje cells cerebellum** *Large, flask-shaped soma with dense, fan-like dendritic tree* - Located in the cerebellar cortex, specifically in the Purkinje layer - Serve as the sole output neurons of the cerebellar cortex - Send inhibitory signals (via GABA) to the deep cerebellar nuclei - Involved in coordination, balance, and fine-tuning motor activity

Question 39

Answer 39

**olfactory bulb and tract** - Cranial Nerve 1 - Sensory - Origin: Olfactory epithelium - Function: Smell

Question 40

Answer 40

**Optic Nerve** *El nervio óptico* - Cranial Nerve 2 - Sensory - Origin: Retina - Function: Vision

Question 41

Answer 41

**Optic Chiasm** The optic chiasm is the X-shaped structure where optic nerve fibers from the nasal (medial) retina of each eye cross to the opposite side. Located just above the pituitary gland and below the hypothalamus. This crossing allows visual information from the right and left visual fields to be processed in the opposite cerebral hemisphere. ``` Only the axons from the nasal (medial) half of each retina cross to the opposite side. Axons from the temporal (lateral) half of each retina do not cross — they stay on the same side (ipsilateral). partial crossing allows visual information from the right visual field of both eyes to be processed in the left hemisphere, and left visual field info to go to the right hemisphere. ```

Question 42

Answer 42

**Oculomotor** *El nervio oculomotor* -Cranial Nerve 3 - Motor - Origin: Midbrain - Function: Controls muscles of the eye - inferior rectus, inferior oblique

Question 43

Answer 43

**Trochlear Nerve** *El nervio troclear* -Cranial Nerve 4 - Motor - Origin: Midbrain - Function: Controls muscles of the eyeball - superior oblique

Question 44

Answer 44

**Trigeminal Nerve** *El nervio trigémino* - Cranial Nerve 5 - Mixed - Origin: Pons, Mouth - Function: Sensory: touch, temperature, pain on face Motor: muscles of jaw

Question 45

Answer 45

**Abducens** *El nervio abducens* - Cranial Nerve 6 - Motor - Origin: Pons - Function: Muscles of the eyeball - lateral rectus *The abducens nerve emerges from the brainstem at the junction of the pons and medulla oblongata, specifically: Medially, between the pyramids (medial) and the pons (superior)*

Question 46

Answer 46

**Facial Nerve** *El nervio facial* - Cranial Nerve 7 - Mixed -Origin: Taste buds, pons Sensory Function: Taste (anterior 2/3rds of tongue) Motor Function: Facial muscles

Question 47

Answer 47

**Vestibulocochlear** *El nervio vestibulococlear* - Cranial Nerve 8 - Sensory - Origin: Inner ear - Function: Hearing and equilibrium *cochlear -> cóclea -> caracol*

Question 48

Answer 48

**Glossopharyngeal** - Cranial Nerve 9 - Mixed - Origin: Tongue, medulla - Sensory Function: Tongue sensations, including taste buds (posterior 1/3 of tongue) - Motor: Swallowing, salivary glands ``` "Glosso-" means tongue (from Greek glossa) "Pharyngeal" refers to the pharynx (throat) ```

Question 49

Answer 49

**Vagus Nerve** *el nervios vago* - Cranial Nerve 10 - Mixed - Origin: Medulla - Sensory Function: pharynx, internal viscera - Motor function: Involuntary motor functions of heart, lungs, digestive tract etc.

Question 50

Answer 50

**Accessory Nerve** *El nervio accesorio / el undécimo par craneal* Cranial Nerve 11 Motor Origin: Upper spinal cord Function: Head and neck muscles

Question 51

Answer 51

**Hypoglossal** Cranial Nerve 12 Motor Origin: Medulla Function: Speach, swallowing *The hypoglossal nerve (CN XII) emerges anterior to the vagus nerve (CN X) in relation to the olive.* *41* *label 9 -> glossopharyngeal nerve* *label 10 -> vagus nerve*