Unit 6 - Brain Anatomy

Abducens n. CNVI

Location:

• Middle cranial fossa

• Orbit

Composition:

• Motor

Motor:

• Lateral rectus muscle

CNS connection:

• Pons (abducens nucleus)

Cranial foramina:

• Superior orbital fissure

Comment:

• Abducens nerve also known as abducent nerve or CN VI

Accessory n. CN XI

Location:

• Vertebral canal (spinal root only)

• Posterior cranial fossa

• Neck

Composition:

• Motor

Motor:

• Cranial part: joins vagus nerve (CN X) to distribute to muscles of palate (except tensor veli palatini), pharynx (except stylopharyngeus), and larynx (intrinsic muscles)

• Spinal part: trapezius and sternocleidomastoid

CNS connection:

• Cranial root: medulla oblongata (nucleus ambiguous)

• Spinal root: ventral horn of C1-4 spinal cord

Cranial foramina:

• Foramen magnum (spinal root only)

• Jugular foramen

Comment:

• Cranial and spinal roots unite in jugular foramen to form accessory nerve

• Cranial part of accessory nerve joins vagus nerve (CN X) and is distributed along its branches to muscles of palate, pharynx, and larynx

• Accessory nerve also known as CN XI

Brainstem

Location:

• Caudal portion of brain

Description:

• Vertical, stalk-like portion of brain

• Includes midbrain, pons, and medulla oblongata

Cerebellum

Location:

• Dorsal to brainstem

Description:

• Composed of many lobes with highly folded cortex

• Attached to pons via cerebellar peduncles

Function:

• Coordinates complex movements

• Monitors muscles to ensure fluid movements

Comment:

• Receives extensive sensory input from body and CNS

• Cerebellar cortex has folds known as folia

• White matter of cerebellar lobes resembles branching tree and is called arbor vitae

• Influences motor function through connections with thalamus and motor cortex

Cerebrum

Location:

• Rostral portion of brain

Description:

• Includes two large cerebral hemispheres separated by longitudinal fissure

• Hemispheres connected by corpus callosum

• Surface gray matter of each hemisphere is known as cerebral cortex

• Within each hemisphere there is a core of white matter

• Additional masses of gray matter located within cerebrum include basal nuclei

Comment:

• Rostral = toward the nose (Latin: rostrum = beak)

Facial n. CN VII

Location:

• Posterior cranial fossa

• Facial canal

• Middle ear

• Face

• Infratemporal fossa

• Oral cavity

Composition:

• Motor

• General sensation

• Special sensation

• Parasympathetic

Motor:

• Muscles of facial expression

• Posterior belly of digastric muscle

• Stylohyoid muscle

• Stapedius muscle

General sensation:

• Small area of skin of auricle of ear

Special sensation:

• Taste from anterior 2/3 of tongue

• Taste from palate

Parasympathetic:

• Lacrimal gland

• Submandibular and sublingual salivary glands

• Mucous glands of nasal cavity, paranasal sinuses, and palate

CNS connection:

• Motor: pons (motor nucleus of facial nerve)

• General sensation: medulla oblongata (spinal trigeminal nucleus)

• Special sensation: medulla oblongata (nucleus of solitary tract)

• Parasympathetic: medulla oblongata (superior salivatory nucleus

Sensory ganglion:

• Geniculate

Cranial foramina:

• Internal acoustic meatus

• Pterygomaxillary fissure

• Stylomastoid foramen

Also known as:

• CN VII

Comment:

• Special sensory and parasympathetic axons, together, form the chorda tympani nerve

• Postganglionic parasympathetic nerve cell bodies located in pterygopalatine and submandibular ganglia

Frontal lobe

Location:

• Anterior portion of cerebral hemisphere

Description:

• Extends from anterior pole of brain to central sulcus

• Contains precentral gyrus

Function:

• Controls voluntary motor activity

• Higher mental processing

• Emotional behavior

• Speech output (i.e., Broca's area - usually in left hemisphere)

Comment:

• Named for overlying bone

Glossopharyngeal n. CN IX

Location:

• Posterior cranial fossa

• Neck

Composition:

• Motor

• General sensation

• Special sensation

• Parasympathetic

Motor:

• Stylopharyngeus muscle

General sensation:

• From middle ear, posterior 1/3 of tongue, and pharynx

Special sensation:

• Taste from posterior 1/3 of tongue

Sensory ganglion:

• Superior and inferior ganglia of glossopharyngeal nerve

Parasympathetic:

• Parotid gland

CNS connection:

• Motor: medulla oblongata (nucleus ambiguus)

• General sensation: medulla oblongata (spinal nucleus of trigeminal nerve)

• Special sensation: medulla oblongata (nucleus of solitary tract)

• Parasympathetic: medulla oblongata (inferior salivatory nucleus)

Cranial foramina:

• Jugular foramen

Comment:

• Has two sensory ganglia (superior and inferior) on nerve in jugular foramen

• Glossopharyngeal nerve also conducts visceral afferent (sensory) impulses from carotid sinus (monitors blood pressure) and carotid body (monitors blood oxygen and carbon dioxide)

• Postganglionic parasympathetic cell bodies located in otic ganglion in infratemporal fossa

• Glossopharyngeal nerve also known as CN IX

Hypoglossal n. CN XII

Location:

• Posterior cranial fossa

• Neck

• Oral cavity

Composition:

• Motor

Motor:

• Genioglossus

• Hyoglossus

• Styloglossus

• Intrinsic muscles of tongue

CNS connection:

• Medulla oblongata (nucleus of hypoglossal nerve)

Cranial foramina:

• Hypoglossal canal

Comment:

• Hypoglossal nerve innervates all tongue muscles except palatoglossus (vagus nerve)

• Intrinsic tongue muscles originate and insert within tongue

• Hypoglossal nerve also known as CN XII

Occipital lobe

Location:

• Posterior portion of each cerebral hemisphere

Description:

• Extends from parieto-occipital sulcus to posterior pole of brain

• Contains lingual gyrus

Function:

• Primary visual area

Comment:

• Named for overlying bone

Olfactory bulb

Location:

• Lies on cribriform plate of ethmoid bone in anterior cranial fossa

• Ventral aspect of frontal lobe of brain

Description:

• Expanded anterior end of olfactory tract

• Site of synapse for olfactory neurons (CN I) after their axons pass through cribriform plate

Olfactory tract

Location:

• Ventral aspect of frontal lobe

• Between olfactory bulb and medial aspect of temporal lobe

Description:

• Bundles of afferent and efferent axons

Optic chiasm

Location:

• Ventral aspect of diencephalon

• Between optic nerves and optic tracts

Description:

• White matter tract composed of axons of retinal ganglion cells from both eyes traveling to thalamus and other brainstem nuclei

• Some axons from each retina decussate (cross) in chiasm to enter opposite optic tract

Comment:

• Retinal ganglion cell axon pathway: optic nerve > optic chiasm > optic tract > brainstem nuclei (including lateral geniculate nucleus of thalamus)

Optic n. CN II

Location:

• Orbit

• Middle cranial fossa

Composition:

• Special sensation

Special sensation:

• Vision

CNS connection:

• Lateral geniculate nucleus of thalamus

Cranial foramina:

• Optic canal

Comment:

• Special sensation includes smell, vision, taste, hearing, and balance

• Optic nerve formed by axons of retinal ganglion cells

• Retinal ganglion cell axon pathway: optic nerve > optic chiasm > optic tract > brainstem nuclei (including lateral geniculate nucleus of thalamus)

• Optic nerve also known as CN II

Temporal bone

Location:

• Lateral and inferior portion of each cerebral hemisphere

• Inferior to lateral sulcus

Description:

• Lateral surface has three parallel gyri

Function:

• Primary hearing and smell areas

• Memory

• Speech perception and recognition (i.e., Wernicke's area - usually in left hemisphere)

Comment:

• Named for overlying bone

Trigeminal n. (CN V)

Location:

• Middle cranial fossa

• Ophthalmic nerve (CN V1): face and orbit

• Maxillary nerve (CN V2): face, orbit, nasal and oral cavities

• Mandibular nerve (CN V3): face, infratemporal fossa, and oral cavity

Composition:

• Ophthalmic nerve: general sensation

• Maxillary nerve: general sensation

• Mandibular nerve: motor and general sensation

Motor:

• Muscles of mastication (mandibular nerve)

• Mylohyoid (mandibular nerve)

• Anterior belly of digastric (mandibular nerve)

• Tensor tympani (mandibular nerve)

• Tensor veli palatini (mandibular nerve)

General sensation:

• Ophthalmic nerve: skin of superior face (forehead, scalp, and upper eyelid), eye, mucosa of anterior nasal cavity, and paranasal sinuses (frontal, ethmoidal, and sphenoidal)

• Maxillary nerve: skin of middle face (cheek, upper lip, and lower eyelid), maxillary teeth and gingiva (gums), mucosa of palate, posterior nasal cavity, and maxillary sinus

• Mandibular nerve: skin of inferior face (mandible, cheek, and lower lip), temple, mucosa lining cheek, mandibular teeth and gingiva (gums), and anterior 2/3 of tongue

Sensory ganglion:

• Trigeminal

CNS connection:

• Pons (principal sensory and motor nuclei of trigeminal nerve)

• Medulla oblongata (spinal nucleus of trigeminal nerve)

Cranial foramina:

• Ophthalmic nerve: superior orbital fissure

• Maxillary nerve: foramen rotundum

• Mandibular nerve: foramen ovale

Comment:

• Trigeminal nerve (CN V) has three divisions (nerves): ophthalmic (CN V1), maxillary (CN V2), and mandibular (CN V3)

• General sensation includes pain, touch, and temperature

• Trigeminal ganglion also known as semilunar ganglion

• Trigeminal nerve also known as CN V

Vagus n. CN X

Location:

• Posterior cranial fossa

• Head

• Neck

• Thorax

• Abdomen

Composition:

• Motor

• General sensation

• Special sensation

• Parasympathetic

Motor:

• Muscles of palate

• Muscles of pharynx

• Intrinsic muscles of larynx

General sensation:

• Thoracic and abdominal viscera

• Epiglottis and laryngopharynx

• External acoustic meatus

Special sensation:

• Taste from epiglottis and surrounding region

Parasympathetic:

• Mucous glands of respiratory and digestive systems in neck (pharynx and larynx), thorax, and abdomen

• Smooth muscle of respiratory and digestive systems in neck (pharynx and larynx), thorax, and abdomen

• Cardiac muscle

CNS connection:

• Motor: medulla oblongata (nucleus ambiguus)

• General sensation: medulla oblongata (spinal nucleus of trigeminal nerve)

• Special sensation: medulla oblongata (nucleus of solitary tract)

• Parasympathetic: medulla oblongata (dorsal nucleus of vagus nerve)

Cranial foramina:

• Jugular foramen

Comment:

• General sensation from thoracic and abdominal viscera only involves stretch (e.g., distention of stomach)

• General sensation from epiglottis and laryngopharynx includes pain, touch, and temperature

• Vagus nerve also innervates carotid and aortic bodies

• Parasympathetic impulses from CNS to effector organ involve two neurons in series (preganglionic and postganglionic)

• Only cranial nerve that extends beyond head and neck

• Vagus nerve also known as CN X

• Vestibulocochlear n. CN VIII

Location:

• Posterior cranial fossa

• Petrous portion of temporal bone

Composition:

• Special sensation

Special sensation:

• Hearing (cochlea)

• Balance (semicircular canals and vestibule)

Sensory ganglion:

• Cochlear (spiral) ganglion (cochlear part of CN VIII)

• Vestibular ganglion (vestibular part of CN VIII)

CNS connection:

• Pons (vestibular nuclei)

• Medulla oblongata (cochlear and vestibular nuclei)

Cranial foramina:

• Internal acoustic meatus

Comment:

• Special sensation includes smell, vision, taste, hearing, and balance

• Vestibulocochlear nerve has two distinct functional components: vestibular (balance) and cochlear (hearing)

• Vestibulocochlear nerve also known as CN VIII

Central sulcus

Location:

• Lateral aspect of cerebral hemisphere

Description:

• Groove on lateral surface of each cerebral hemisphere

• Forms boundary between frontal and parietal lobes

• Located between precentral and postcentral gyri

Lateral sulcus

Location:

• Lateral aspect of each cerebral hemisphere

Description:

• Deep groove separating temporal from frontal and parietal lobes

Occipital lobe

Parietal lobe

Location:

• Lateral surface of each cerebral hemisphere of brain

Description:

• Extends from central sulcus (rostral) to parieto-occipital sulcus (caudal)

• Includes postcentral gyrus

Function:

• Reception of general sensory information from body

• Tactile object recognition

• Language, verbatim repetition of terms (i.e., Wernicke's area - usually in left hemisphere)

Comment:

• Named for overlying bone

Postcentral gyrus

Location:

• Lateral aspect of each cerebral hemisphere

Description:

• Distinct "fold" at anterior border of parietal lobe

• Located along posterior edge of central sulcus

Function:

• Receives somatosensory information from body

Comment:

• Also called primary somatosensory cortex

Precentral gyrus

Location:

• Lateral aspect of each cerebral hemisphere

Description:

• Distinct "fold" at posterior border of frontal lobe

• Located along anterior edge of central sulcus

Function:

• Controls voluntary movement

Comment:

• Also called primary motor cortex

Temporal lobe

Location:

• Lateral and inferior portion of each cerebral hemisphere

• Inferior to lateral sulcus

Description:

• Lateral surface has three parallel gyri

Function:

• Primary hearing and smell areas

• Memory

• Speech perception and recognition (i.e., Wernicke's area - usually in left hemisphere)

Comment:

• Named for overlying bone

Anterior lobe of cerebellum

Location:

• Cerebellum

Description:

• The most anterior lobe of the cerebellar hemisphere

• There is a right and left hemisphere of the cerebellum

Arbor vitae

Location:

• Cerebellum

Description:

• Composed of the white matter of cerebellar lobes

• It's pattern resembles a branching tree

Cerebellum

Cerebral aqueduct

Location:

• Midbrain

Description:

• Narrow midline channel between third and fourth ventricles

• Filled with cerebrospinal fluid

Comment:

• Cerebral ventricular system includes: (1) paired lateral ventricles; (2) interventricular foramena (Monro); (3) unpaired third ventricle; (4) cerebral aqueduct (Sylvius); and (5) unpaired fourth ventricle

Cerebrum

Choroid plexus

Location:

• Lateral, third, and fourth ventricles of brain

Description:

• Tufts of capillaries covered by specialized ependymal cells that line ventricles

Function:

• Specialized ependymal cells produce cerebrospinal fluid

Cingulate gyrus

Location:

• Cerebrum

Description:

• Located superior to the corpus callosum in frontal and parietal lobes

• Part of cerebellar cortex

• One component of limbic system, which is important for emotion and learning

Corpus callosum

Location:

• Brain, between cerebral hemispheres

Description:

• Large myelinated fiber tract connecting right and left cerebral hemispheres

• Forms floor of longitudinal fissure

Diencephalon

Location:

• Cerebrum

Description:

• Composed of thalamus, hypothalamus, and epithalamus

Function:

• Thalamic nuclei relay sensory information to cerebral cortex

• Hypothalamic nuclei maintain homeostasis

• Epithalamus includes pineal gland (produces melatonin)

Folia

Location:

• Cerebellum

Description:

• Folds of the cerebellum cortex

Fornix of brain

Location:

• Brain

• Suspended from corpus callosum and septum pellucidum

Description:

• Arched fiber tract connecting hippocampus to mammillary bodies

Fourth ventricle

Location:

• Between cerebellum and brainstem

Description:

• Single, midline, pyramidal cavity filled with cerebrospinal fluid (CSF)

• Has choroid plexus that produces CSF

• Connected to third ventricle via cerebral aqueduct

• Has three foramina that open into subarachnoid space

• Continuous with central canal of spinal cord

Comment:

• Cerebral ventricular system includes: (1) paired lateral ventricles; (2) interventricular foramena (Monro); (3) unpaired third ventricle; (4) cerebral aqueduct (Sylvius); and (5) unpaired fourth ventricle

Frontal lobe

Hypothalamus

Location:

• Ventral diencephalon

Description:

• Collection of nuclei located inferior to thalamus

• Includes infundibulum and mammillary bodies

Function:

• Considered master control center for endocrine system

• Secretes releasing and inhibiting hormones that control anterior pituitary gland

• Produces hormones that are transported to and stored in posterior pituitary gland

• Controls autonomic nervous system

• Regulates body temperature, food, and water intake

• Regulates emotional behavior

• Maintains sleep/wake cycle

Inferior colliculus

Location:

• Midbrain

Description:

• Pair of rounded elevations on dorsal aspect of midbrain

• Located caudal (posterior) to superior colliculus

Function:

• Primary midbrain nucleus of the auditory pathway

• Important in hearing the origin of sound, understanding human speech, and the auditory reflex

Infundibulum of pituitary gland

Location:

• Ventral surface of diencephalon (hypothalamus) at midline

Description:

• Contains hypothalamo-hypophysial tract

• Contains hypothalamo-hypophysial portal vein that carries hypophysiotropic hormones to the anterior pituitary

Function:

• Transmits antidiuretic hormone (ADH) and oxytocin through hypothalamo-hypophysial tract to posterior pituitary

Comment:

• Latin: infundibulum = a funnel

Interthalamic adhesion

Location:

• Thalamus

Description

• Small structure composed of flattened tissue that contents the two parts of thalamus at medial surface

• Also known as middle commissure or intermediate mass

Mamillary body

Location:

• Ventral surface of diencephalon (hypothalamus)

Description:

• Paired, small, rounded projections

• Site of hypothalamic-mammillary nuclear complex

Function:

• Involved in regulation of autonomic functions, emotional behavior, and memory

Medulla oblongata

Location:

• Most caudal portion of brain

Description:

• Extends from pons to spinal cord

• Associated with cranial nerves IX, X, XI, and XII

Function:

• Contains respiratory, cardiac, and vasomotor centers

Mesencephalon

Location:

• Brainstem

• Between diencephalon and pons

Description:

• Composed of white matter tracts and gray matter nuclei

• Associated with cranial nerves III and IV

• Prominent features include superior and inferior colliculi, cerebral peduncles, substantia nigra, and cerebral aqueduct

Function:

• Coordinates movements in response to visual and auditory stimuli

• Conveys motor information from cerebral cortex to pons

• Conveys sensory information from spinal cord to thalamus

Also known as:

• Also known as mesencephalon

Optic chiasm

Pineal gland

Location:

• Diencephalon (epithalamus)

Description:

• Pea-sized endocrine gland

• Attached to roof of third ventricle

Function:

• Secretes melatonin (involved in sleep/wake cycles)

• Modified activity in endocrine organs (pituitary, pancreas, parathyroid, suprarenal, and gonads)

Also known as:

• Pineal body

Pituitary gland

Location:

• Midline of middle cranial fossa

• Rests in hypophysial fossa of sphenoid bone

Description:

• Small, oval bilobed endocrine gland

• Two functional lobes: anterior (adenohypophysis) and posterior (neurohypophysis)

• Connected by infundibulum to hypothalamus

Function:

• Anterior pituitary produces the following hormones: thyroid-stimulating (TSH), prolactin (PRL), adrenocorticotropic (ACTH), growth (GH), luteinizing (LH), melanocyte-stimulating (MSH), and follicle-stimulating (FSH)

• Posterior pituitary stores and releases: antidiuretic hormone (ADH) and oxytocin (OT)

Also known as:

• Hypophysial gland or hypophysis

Comment:

• Posterior pituitary does not produce any hormones; ADH and OT produced in hypothalamus

Pons

Location:

• Ventral aspect of brainstem

• Between midbrain (rostral) and medulla oblongata (caudal)

Description:

• Characterized by distinct ventral "bulge"

• Attached to cerebellum by middle cerebral peduncle

• Associated with cranial nerves V, VI, VII, and VIII

Function:

• Involved in control of sleep and respiration

• Transfer of information to and between cerebellar hemispheres

Comment:

• Latin: pons = bridge

Posterior lobe of cerebellum

Location:

• Cerebellum

Description:

• The most posterior lobe of the cerebellar hemisphere

• There is a right and left hemisphere of the cerebellum

Primary fissure of cerebellum

Location:

• Cerebellum

Description:

• The fissure that separates the anterior lobe of the cerebellum from posterior lobe of cerebellum in each hemisphere

• There is a right and left hemisphere of the cerebellum

Septum pellucidum

Location:

• Suspended between lateral ventricles

• Perpendicular to corpus callosum

Description:

• Thin sheet of non-neuronal tissue separating right and left lateral ventricles

Superior colliculus

Location:

• Midbrain

Description:

• Pair of rounded elevations on dorsal aspect of midbrain

Function:

• Coordinates orienting movements of eyes and head

Thalamus

Location:

• Diencephalon

Description:

• Paired groups of nuclei separated by third ventricle

• Largest portion of the diencephalon

• Composed primarily of gray matter

Function:

• Primarily for relay of sensory information to cortex

• Relay of motor information for movement planning

Third ventricle

Location:

• Diencephalon

Description:

• Single, midline cavity filled with cerebrospinal fluid (CSF)

• Has choroid plexus that produces CSF

• Connected to lateral ventricles via interventricular foramena

• Connected to fourth ventricle via cerebral aqueduct

Comment:

• Cerebral ventricular system includes: (1) paired lateral ventricles; (2) interventricular foramena (Monro); (3) unpaired third ventricle; (4) cerebral aqueduct (Sylvius); and (5) unpaired fourth ventricle

Basal ganglia

Location:

• Cerebrum

Description:

• Paired masses of gray matter located deep in each cerebral hemisphere

• Composed of corpus striatum (caudate nucleus, putamen, and globus pallidus), amygdaloid body, and claustrum

Function:

• Planning and execution of movement

• Controls highly practiced and subconscious movements

• Muscle tone and posture

Also known as:

• Basal ganglia

Fornix of brain

Location:

• Brain

• Suspended from corpus callosum and septum pellucidum

Description:

• Arched fiber tract connecting hippocampus to mammillary bodies

Insular lobe

Location:

• Deep in each lateral sulcus

Description:

• Cerebral lobe

• Not visible from surface

Function:

• Understanding spoken language

• Perception of taste and smell

• Integrates information from visceral receptors

Also known as:

• Insula or isle of Reil

Lateral ventricle

Location:

• Deep within cerebral hemisphere

Description:

• Paired cavity filled with cerebrospinal fluid (CSF)

• Has anterior, posterior, and inferior extensions (horns)

• Has choroid plexus that produces CSF

• Connected to third ventricle via interventricular foramen

Comment:

• Cerebral ventricular system includes: (1) paired lateral ventricles; (2) interventricular foramina (Monro); (3) unpaired third ventricle; (4) cerebral aqueduct (Sylvius); and (5) unpaired fourth ventricle

Amygdala

Location:

• Cerebral hemisphere

• Expanded region at tail of caudate nucleus

Description:

• Collection of gray matter deep inside each cerebral hemisphere

• Part of basal nuclei

Function:

• Involved in expression of emotions, especially fear

• Involved in formation of memories related to emotional events

• Part of the limbic system

Comment:

• Also called amygdaloid body

• Basal nuclei also called basal ganglia

Basal ganglia

Choroid plexus

Hypothalamus

Lateral ventricle

Thalamus

Cerebellum

Cerebrum

Glossopharyngeal

Hypoglossal

Occipital lobe

Oculomotor

Location:

• Middle cranial fossa

• Orbit

Composition:

• Motor

• Parasympathetic

Motor:

• Medial rectus muscle

• Superior rectus muscle

• Inferior rectus muscle

• Inferior oblique muscle

• Levator palpebrae superioris muscle

Parasympathetic:

• Pupillary sphincter muscle (constriction of pupil)

• Ciliary muscle (permits lens to thicken for accommodation)

CNS connection:

• Midbrain (oculomotor and accessory oculomotor nuclei)

Cranial foramina:

• Superior orbital fissure

Comment:

• Rectus and oblique muscles are extrinsic eye (extra-ocular) muscles

• Postganglionic parasympathetic cell bodies located in ciliary ganglion in the orbit

• Oculomotor nerve also known as CN III

Olfactory bulb

Olfactory tract

Optic chiasm

Optic n. CN II

Optic tract

Temporal lobe

Trigeminal CN V

Vagus

Vestibulocochlear n. CN VIII

Central sulcus

Frontal lobe

Longitudinal fissure

Occipital lobe

Parietal lobe

Postcentral gyrus

Precentral gyrus

Temporal lobe

Location:

• Lateral and inferior portion of each cerebral hemisphere

• Inferior to lateral sulcus

Description:

• Lateral surface has three parallel gyri

Function:

• Primary hearing and smell areas

• Memory

• Speech perception and recognition (i.e., Wernicke's area - usually in left hemisphere)

Comment:

• Named for overlying bone

Anterior lobe of cerebellum

Arbor vitae

Cerebral aqueduct

Folia

Fornix of brain

Fourth ventricle

Hypothalamus

Inferior colliculus

Infundibulum of pituitary gland

Interthalamic adhesion