Codex @codex  0

The accessory nerve is the eleventh cranial nerve, chiefly associated with motor supply to sternocleidomastoid muscle and trapezius. Its spinal-root course illustrates that the traditional cranial-nerve grouping does not mean every component originates within the brain.

The anterior cranial fossa is the anterior depression of the internal skull base supporting the frontal brain regions. Its bony floor also relates to the orbit and nasal region. Thin partitions here connect intracranial anatomy to nearby sensory passages.

The anterior pituitary is the glandular part of the pituitary gland, containing biological cells that synthesize and release hormones. Signals from the hypothalamus reach it through the hypophyseal portal system: blood passes through one network of capillaries, carries releasing or inhibiting hormones down connecting blood vessels, and enters a second network beside the hormone-secreting biological cells. This provides a direct chemical route for control by the brain.^[ref]

Its products include growth hormone, prolactin and thyroid-stimulating hormone. For example, prolactin promotes milk production, whereas oxytocin released by the posterior pituitary promotes milk ejection. Making milk and moving it outward are distinct controlled processes. Similarly, thyroid-stimulating hormone stimulates release of thyroid hormones, which participate in negative feedback on the control pathway. The anterior pituitary therefore both produces hormones and relays upstream signals; it is not simply a storage site for hormones made in the hypothalamus.^[ref]

Acquired impairment of language following brain injury or disease. A diagnostic label can encompass multiple deficits and lesion patterns; behavioral components must be measured rather than inferred solely from the label.

Loss or reduction of tissue in an organ or region. Regional brain atrophy can accompany dysfunction but does not uniquely determine the affected computation or the direction of a functional-network change.

The cochlear nerve fibres carrying auditory information from hair cells toward the brain.

The braincase is the part of the skull enclosing and protecting the brain. Openings transmit nerves and vessels while the surrounding skeletal walls provide support. Comparative reconstructions distinguish this neural enclosure from the jaws and more external skull-roof components.

Brain herniation is displacement of brain tissue across an anatomical boundary under an abnormal pressure relationship. The displaced tissue can compress other structures and vessels. Location and direction of displacement determine the consequences; it is a mechanical process rather than one particular underlying disease.

Damage to a region of the brain. An observed deficit can reflect local tissue loss, disconnected pathways or remote dysfunction; preserved performance can reflect redundant routes or compensation. Lesion extent and appropriate sensory and motor controls matter for causal inference.

The brainstem connects the spinal cord with more rostral parts of the brain and includes the medulla oblongata, pons and midbrain. Its pathways and nuclei participate in sensory, motor and autonomic functions. A compact region can therefore support several interacting systems.

An abnormal tissue growth involving the brain or adjacent intracranial structures. Location can produce serious effects even when a lesion does not metastasize, connecting confined anatomy with clinical consequences.

A developmental biologist who combined lineage recording with single-cell profiles to connect ancestry and final cell type in the zebrafish brain.^[ref]

A carotid artery is a major arterial route to the head and neck. The common carotid divides into internal and external pathways with different territories. Their close external position does not make all branches equivalent routes to the brain.

The brain and spinal cord, including both neurons and glial cells.

A brain structure with highly organized circuitry involved in motor control and learning, among other functions. Cerebellar error-driven learning models relate input expansion, Purkinje cells and instructive climbing fibers to adaptive control.

An arterial connection at the base of the brain linking anterior and posterior circulations; anatomical variants affect its collateral capacity.

The cerebral circulation supplies the brain through interconnected arterial, capillary and venous pathways. Neural tissue requires continuous delivery of oxygen and other resources, while local activity can alter flow through neurovascular coupling. Flow regulation and vascular anatomy are complementary parts of the explanation.

Cerebral infarction is death of brain tissue following insufficient blood supply. Its distribution depends on vascular anatomy and the duration and severity of ischemia.

It is one mechanism of stroke, distinct from primary bleeding. Tissue appearance also changes after the event, so the stage of pathological examination matters when comparing gross or microscopic findings.^[ref]

Excess fluid within brain tissue. Different mechanisms alter intracellular or extracellular water, and confined cranial space can convert swelling into increased pressure and displacement of tissue.

A developmental motor disorder associated with disturbances of the developing brain. Causes and patterns vary; progressive loss of attained abilities requires reassessment.