Cranial Bones, Nerves & Neural Tube Development

The frontal bone forms the anterior boundary of the anterior cranial fossa.

The glossopharyngeal nerve (CN IX) does not pass through the foramen ovale. It passes through the jugular foramen.

The temporal lobe is most likely involved in an infection of the middle cranial fossa, as it resides within this fossa.

The thalamus, a part of the diencephalon, is not derived from the hindbrain (rhombencephalon). It develops from the forebrain (prosencephalon).

The alar plate of the neural tube gives rise to sensory neurons. These neurons are responsible for transmitting sensory information to the central nervous system.

A failure of differentiation of the basal plate during neural tube development would most affect the spinal cord motor neurons. These neurons are responsible for voluntary movement.

The anterior cerebral artery supplies the anterior part of the brain, including the medial aspect of the frontal and parietal lobes.

A blockage in the middle cerebral artery (MCA) can lead to a range of symptoms, including hemianopia (visual field loss), hemiparesis (weakness of one side of the body), and dysphasia (speech difficulty).

The Circle of Willis, a critical vascular structure, connects the internal carotid and vertebral arteries. This connection provides alternative pathways for blood flow to the brain.

Dural folds are invaginations of the dura mater that help divide the brain into functional regions. They do not directly cushion, provide nutrients, or protect mechanically.

Arachnoid granulations are structures involved in the absorption of cerebrospinal fluid (CSF) from the subarachnoid space back into the venous system.

A subarachnoid hemorrhage, bleeding into the subarachnoid space, is most likely to cause a sudden headache and neck stiffness.

The foramen of Monro, also known as the interventricular foramen, connects the lateral ventricles to the third ventricle. It allows the flow of CSF between these chambers.

The choroid plexus is responsible for producing cerebrospinal fluid (CSF). These specialized structures are located within the ventricles.

A blockage in the cerebral aqueduct would lead to the enlargement of the lateral ventricle, as CSF would accumulate upstream of the blockage.

The facial nerve (CN VII) is responsible for the sensation of taste from the anterior two-thirds of the tongue. It also controls facial expressions and tear production.

The mandibular nerve (V3), a branch of the trigeminal nerve, exits the skull through the foramen ovale. It provides sensory and motor innervation to the lower face and jaw.

The anterior horn of the spinal cord is primarily responsible for motor control of the limbs. It houses motor neurons that innervate muscles.

A lesion in the posterior horn of the spinal cord would affect sensory perception, including touch, temperature, and proprioception. The posterior horn processes sensory information.

The oculomotor nerve (CN III) emerges from the midbrain. It controls eye movements, pupil constriction, and eyelid elevation.

A lesion in the pons, a part of the brainstem, could lead to paralysis of facial muscles, affecting facial expressions and speech. The pons houses the facial nerve nucleus.

The cerebellum is responsible for coordinating voluntary movements, maintaining balance and posture, and modulating motor learning. It receives input from the cerebrum and the brainstem.

The thalamus, located in the diencephalon, is responsible for relaying sensory information to the cerebral cortex. It acts as a sensory filter and gatekeeper.

The sympathetic nervous system has a wide range of effects, including increasing heart rate, dilating pupils, and inhibiting digestion. It prepares the body for "fight or flight" responses.

The parasympathetic nervous system is associated with "rest and digest" functions. It slows heart rate, stimulates digestion, and promotes relaxation.

CT scan, with its ability to visualize dense structures, is the most commonly used imaging technique for acute stroke.

The frontal lobes of the brain are best seen on a coronal MRI section. This section cuts the brain perpendicular to the ground, revealing the frontal, parietal, and temporal lobes.

The posterior cranial fossa houses the brainstem, which includes the medulla oblongata, pons, and midbrain, and the cerebellum. This fossa forms the base of the skull.

The foramen magnum, located in the posterior cranial fossa, transmits the spinal cord and the vertebral arteries. It represents the opening at the base of the skull where the brainstem connects to the spinal cord.

The maxillary nerve (V2), a branch of the trigeminal nerve, passes through the foramen rotundum. It provides sensory innervation to the face, teeth, and palate.

During neural tube development, the forebrain (prosencephalon) gives rise to the thalamus and hypothalamus. These structures are involved in sensory relay, endocrine function, and regulation of basic bodily functions.

The alar plate of the neural tube gives rise to sensory neurons. These neurons are responsible for receiving and transmitting sensory information.

Failure of the neural tube to close properly can result in spina bifida, a congenital neural tube defect that affects the spinal cord and vertebral column. The severity can vary depending on the extent of the defect.

The posterior cerebral artery supplies the occipital lobe, which is responsible for visual processing. It also supplies a portion of the temporal lobe.

The anterior spinal artery is the primary blood supply to the spinal cord. It runs along the ventral aspect of the cord, supplying motor neurons and other structures.

A stroke in the anterior cerebral artery (ACA) most commonly affects the lower limbs. This artery supplies the medial aspects of the frontal and parietal lobes, which control motor function of the legs.

The pia mater is the innermost meningeal layer. It is closely attached to the surface of the brain and spinal cord, following the contours of the nervous tissue.

The subarachnoid space is filled with cerebrospinal fluid (CSF) and houses the brain's blood vessels. It provides cushioning and mechanical protection to the brain.

A subdural hematoma, a blood clot in the subdural space, occurs between the dura mater and arachnoid mater. It is often caused by a head injury.

The foramen of Monro, also called the interventricular foramen, connects the lateral ventricles to the third ventricle. This opening allows CSF to flow between these chambers.

The choroid plexus, a specialized vascular structure, is present in all four brain ventricles (lateral, third, and fourth). It is responsible for producing cerebrospinal fluid (CSF).

A blockage in the foramen of Monro can lead to hydrocephalus, a condition characterized by excessive CSF accumulation in the ventricles. This obstruction prevents CSF from flowing freely.

The trigeminal nerve (CN V) is responsible for innervating the muscles of mastication: the masseter, temporalis, and pterygoids. It also provides sensory innervation to the face.

The glossopharyngeal nerve (CN IX) is responsible for providing sensation to the posterior third of the tongue, including taste. It also controls the pharynx and salivary glands.

A patient with a lesion of the vagus nerve (CN X) may experience difficulty swallowing (dysphagia), hoarseness of voice, and other symptoms related to the dysfunction of the pharynx, larynx, and other organs.

The dorsal root ganglion, located within the dorsal root of the spinal nerve, contains the cell bodies of sensory neurons. These neurons transmit sensory information from the body to the spinal cord.

A lesion in the lateral corticospinal tract would result in loss of motor control in the lower limbs. This tract carries motor signals from the cerebral cortex to the spinal cord, controlling voluntary movements.

The medulla oblongata, a part of the brainstem, contains nuclei responsible for regulating vital functions, including heart rate, respiration, blood pressure, and swallowing. It also controls reflexes and sensory pathways.

The substantia nigra, a dark-pigmented structure in the midbrain, is involved in regulating mood, movement, and reward. It produces dopamine, a neurotransmitter crucial for motor control and motivation.

The pons, a part of the brainstem, contains nuclei for cranial nerves V (trigeminal), VI (abducens), VII (facial), and VIII (vestibulocochlear). These nerves control various functions, including sensation, eye movements, facial expressions, and hearing.

The cerebellum, a highly folded structure at the back of the brain, coordinates voluntary movements, maintains balance and posture, and modulates motor learning. It receives input from the cerebrum and the brainstem.

The pineal gland, a small endocrine gland located in the diencephalon, produces melatonin, a hormone involved in regulating sleep-wake cycles and circadian rhythms. It also plays a role in sexual development.

Damage to the cerebellum can lead to ataxia, a loss of coordination of voluntary movements, and difficulty with balance and walking. This can affect fine motor skills and gait.

The central sulcus separates the frontal and parietal lobes of the brain. This deep groove marks the division between the motor cortex in the frontal lobe and the sensory cortex in the parietal lobe.

Broca's area, located in the frontal lobe, is responsible for speech production and articulation. It is involved in planning and executing the motor movements required for speech.

The temporal lobe, located below the frontal and parietal lobes, is primarily involved in auditory processing, memory formation, and language comprehension. It houses the hippocampus and the amygdala.

Damage to the left hemisphere of the brain, particularly in areas responsible for language, is most likely to result in aphasia, a communication disorder characterized by difficulty with speech, writing, and understanding language.

The sympathetic nervous system prepares the body for the "fight or flight" response. It increases heart rate, dilates pupils, and diverts blood flow to skeletal muscles, preparing the body for action.

The sympathetic nervous system has a more widespread effect on the body compared to the parasympathetic system. Its fibers reach many organs, including the heart, lungs, digestive system, and sweat glands.

Acetylcholine is the neurotransmitter primarily used by the parasympathetic nervous system at the postganglionic synapse. It acts on target organs to promote rest and relaxation.

MRI (Magnetic Resonance Imaging) is best suited for visualizing soft tissue structures, like the brain and spinal cord, due to its ability to differentiate between different types of tissues.

White matter lesions in periventricular regions, often seen on brain MRI, are a typical finding in patients with multiple sclerosis. These lesions represent areas of inflammation and demyelination.

A hyperdense area on a CT scan is indicative of an acute hemorrhagic stroke, where bleeding has occurred in the brain tissue. Blood appears denser than normal brain tissue.

An epidural hematoma on imaging typically has a shape, limited to one side of the brain. This is because the blood is located between the dura mater and the skull bone, creating a distinct shape.

The dorsal column, located in the posterior part of the spinal cord, is responsible for carrying sensory information related to touch, pressure, vibration, and proprioception. It transmits these signals to the brain for processing.

The white matter of the spinal cord is primarily composed of myelinated axons, which are nerve fibers covered in a fatty substance called myelin. Myelin speeds up the transmission of nerve impulses.

The corticospinal tract, a major motor pathway, carries motor signals from the cerebral cortex to the spinal cord, controlling voluntary movements of the limbs and trunk.

The medulla oblongata, a part of the brainstem, houses nuclei that control vital functions such as heart rate, respiration, blood pressure, and swallowing. It also plays a role in sensory and motor pathways.

The superior colliculus, located in the midbrain, is involved in vision and eye movements. It receives input from the retina and other visual structures, controlling eye movements and reflexes.

The oculomotor nerve (CN III) exits the brainstem at the level of the midbrain. It controls eye movements, pupil constriction, and eyelid elevation.

The cavernous sinus, a large venous space in the skull, houses the oculomotor (CN III), trochlear (CN IV), ophthalmic (CN V1), and abducens (CN VI) nerves. A mass or thrombosis in this space can affect these nerves.

The myelencephalon develops later as part of the rhombencephalon. It is not one of the primary brain vesicles.

The prosencephalon, or forebrain, is the primary brain vesicle that gives rise to the telencephalon and diencephalon. Abnormalities in this region can lead to hydrocephalus and forebrain malformations.

The right middle cerebral artery (MCA) supplies the lateral aspects of the frontal, parietal, and temporal lobes. A stroke in this artery can cause weakness, paralysis, and speech difficulties on the contralateral side of the body.

The anterior cerebral artery (ACA) primarily supplies the medial aspects of the frontal and parietal lobes, which control motor function of the lower limbs. A stroke in the ACA can lead to paralysis and sensory deficits in the legs.

A subarachnoid hemorrhage involves bleeding into the subarachnoid space, the space between the arachnoid mater and the pia mater. The subarachnoid space contains cerebrospinal fluid (CSF) and blood vessels.

The denticulate ligament, a modification of the pia mater, helps anchor the spinal cord to the dura mater. It prevents the spinal cord from moving freely within the vertebral canal.

The cavernous sinus, a large venous space located near the base of the skull, houses the oculomotor (CN III), trochlear (CN IV), ophthalmic (CN V1), and abducens (CN VI) nerves. Thrombosis in this sinus can affect these nerves.

Hydrocephalus ex vacuo, a type of hydrocephalus characterized by ventricular enlargement without obstruction of CSF flow, is often associated with brain atrophy. This occurs when brain tissue shrinks, leaving a larger space for CSF to occupy.

Obstructive hydrocephalus occurs when there is blockage in the flow of CSF, leading to increased pressure and ventricular enlargement. This can cause symptoms such as headache, vomiting, and neurological deficits.

The facial nerve (CN VII) is responsible for taste on the anterior 2/3 of the tongue, controls facial expressions, and innervates salivary glands. Damage to this nerve can affect taste, facial movement, and tear production.

Central cord syndrome, a type of spinal cord injury, is characterized by weakness and sensory loss in the upper limbs, often sparing the lower limbs. It is caused by damage to the central part of the spinal cord.

The medulla oblongata, a part of the brainstem, contains nuclei for cranial nerves IX (glossopharyngeal), X (vagus), and XII (hypoglossal), which are involved in swallowing, speech, and sensory functions.