…By the Way, Where Is the Fornix???

Home , Fornix (neuroanatomy), Hypothalamic sulcus, Interthalamic adhesion, Posterior commissure

Resources …By the way, – H. Blumenfeld. Neuroanatomy through clinical cases where is the fornix??? (Sinauer 2002). – Digital anatomist: • http://www9.biostr.washington.edu/da.html An introduction to gross neuroanatomy –Sylvius: • http://www.sylvius.com/ Marco L. Loggia, PhD [email protected]

Some slides kindly provided by E. Duerden, UMontreal. Brigham and Women’s Hospital (Anesthesiology) Mass General Hospital (Psychiatry) All images and animations included in this presentation are from the Digital Harvard Medical School Anatomist website, unless otherwise specified.

Orientation Orientation

Humans, however, have an upright posture… VENTRAL = towards the belly (=‘ventrum’ in latin) DORSAL = towards the back (=‘dorsum’in latin) ROSTRAL = towards the snout (‘rostrum’=beak in latin) ABOVE CAUDAL = towards the tail (=‘cauda’ in latin) M-D junction

BELOW M-D junction

In animals with a linear organization of the CNS, terminology is straightforward:

= Watch out! ‘Superior’=‘Dorsal’ above the midbrain; =‘Rostral’ in the midbrain or below

Blumenfeld, 2002. © Sinauer (2002) Sylvius.com Blumenfeld (adapted). © Sinauer (2002)

1 Orientation Orientation

MEDIAL = close to the midline LATERAL = close to the sides Horizontal (axial/transverse) Coronal Sagittal

LATERALMEDIAL LATERAL

Horizontal Sagittal Coronal

Think about the horizon! Imagine a tiara-like crown! Think about the bow of an archer! VENTRAL

Blumenfeld. © Sinauer (2002)

Major subdivisions Orientation of the encephalon

Telencephalon Horizontal (axial/transverse) Coronal Sagittal -Cereb. Hemispheres (including cortex and subcortical structures)

Diencephalon -thalamus -hypothalamus -other associated structures Horizontal Sagittal Coronal

Brainstem -Midbrain (mesencephalon) -Pons* Think about the horizon! Imagine a tiara-like crown! Think about the bow of an archer! -Medulla oblongata (myelencephalon)

Cerebellum* Sylvius.com * Pons+cerebellum = metencephalon

2 The brainstem The brainstem

Cerebral peduncles Midbrain Midbrain

Pons Pons

Medulla Oblongata Medulla Oblongata Cranial nerves

Inferior Olives

Pyramids Cerebellum

The brainstem The brainstem

Sup. colliculus

Midbrain Inf. colliculus

Pons

Cerebellar Medulla Peduncles Oblongata

3 The brainstem The brainstem

Tips to find the medulla on axial slices:

I can see two ventral ‘bumps’ (PYRAMIDS)

Midbrain

Pons Lateral to these, two more subtle ‘bumps’ Medulla Oblongata (INF. OLIVES)

I am the level of the MEDULLA! Cerebellum

The brainstem The brainstem

Tips to find the pons on axial slices: Tips to find the midbrain on axial slices:

I can see the large ‘belly’ I see MICKEY! (the ears=cerebral peduncles)

I am the level of the PONS! I am the level of the MIDBRAIN!

4 The diencephalon The diencephalon

The ICECREAM tip: Thalamus is the SCOOP, the hypothalamus the CONE! Hypothalamic sulcus

Thalamus

Hypothalamus

The diencephalon The diencephalon

Optic Optic chiasm chiasm

Infundibulum of the pituitary gland Infundibulum Hypothalamus lies of the Pituitary dorsal to these structures gland

Mammillary bodies Mammillary bodies

5 The diencephalon The diencephalon

Thalami

The ventricular system The ventricular system

Lateral v.

Lateral ventricles (inside the hemispheres) Third v. Cerebral aqueduct (tiny canal inside the midbrain)

Cerebral aqueduct Third ventricle (between the 2 thalami; Fourth Fourth v. & at the center of the hypothalamus) ventricle (between pons/upper medulla and cerebellum)

6 The ventricular system Cerebral Hemispheres

Foramen of Monro Third ventricle • 2 hemispheres, interconnected by: corpus callosum, anterior commissure, posterior commissure and (in some individuals) interthalamic adhesion (aka massa intermedia). Cerebral aqueduct Fourth ventricle

Corpus callosum

Thalamus Anterior Hypothalamus Commissure (tip: rostral to the fornix!) Midbrain

Pons Posterior commissure (tip: dorsal to the top of the aqueduct!) Medulla Oblongata Cerebellum

Cerebral Hemispheres Cortex

• 2 hemispheres, interconnected by: corpus callosum, anterior commissure, posterior commissure and (in some individuals) interthalamic adhesion. • Composed of GYRI (the ‘HILLS’) and SULCI (the ‘VALLEYS’)

• In each hemisphere: cortex (gyri, sulci), white matter and subcortical structures • If a sulcus is very deep Î FISSURE (E.g. Lateral fissure) (including hippocampus, amygdala and basal ganglia). • Some sulci run LONGITUDINALLY, others in a MEDIAL-LATERAL direction

• 4 ‘undisputed’ lobes (frontal, parietal, temporal and occipital) + insula (sometimes

referred to as ‘the fifth lobe’).

7 Cortex Cortex Central (Rolandic) fissure

Parieto-occipital fissure

PARIETAL LOBE

FRONTAL LOBE OCCIPITAL LOBE

TEMPORAL LOBE

Lateral (Sylvian) fissure Preoccipital notch ©

Beal, LSU (2005). Modified

Cortex Cortex Post central gyrus Central sulcus Tips to find the central sulcus: superior parietal lobule precentral gyrus 1) SFS stops at the precentral gyrus; 2) Look for the ‘Omega shape’ (motor hand area) Superior frontal Intraparietal fissure gyrus

middle frontal gyrus Inferior parietal lobule

inferior frontal gyrus

superior temporal gyrus Lateral sulcus middle temporal gyrus

From Emma Duerden, Inferior temporal gyrus with permission (modified) Courtesy of Digital Anatomist Project at Univ of Washington

8 Cortex Cortex Tip to find the intraparietal sulcus:

The lateral fissure and superior temporal sulcus stop at the Inf par lobule

Cortex Cortex

Parieto-occipital Cingulate gyrus fissure

cuneus

Calcarine fissure

uncus Lingual gyrus

Parahippocampal From Emma Duerden, Blumenfeld, 2002. © Sinauer (2002) gyrus Courtesy of Digital Anatomist Projectwith at Univ. permission of Washington

9 Cortex Cortex

Insula

Heschl’s (transverse) gyri

From Emma Duerden, From Emma Duerden, Digital Anatomist Project at Univ. of Washington modified, with permission Digital Anatomist Project at Univ. of Washington with permission (modified)

Hippocampus Hippocampus

Tip to find the hippocampus: Look below the inferior horn of the lateral ventricle! Hippocampus The fornix connects the hippocampus to the mammillary bodies

Lateral ventricle

Inferior horn of the lateral ventricle

Hippocampus Fornix (the axons of the hippocampal neurons)

10 Hippocampus and Amygdala The basal ganglia Tip to find the amygdala: Look rostral to the hippocampus!

Amygdala Caudate nucleus

Lentiform nucleus (=putamen+ globus pallidus)

Hippocampus

The basal ganglia The basal ganglia Tips to find the basal ganglia: 1) The nucleus bulging into the lateral ventricle is the head of the caudate 2) look for the L shaped white matter (internal capsule)! 3) ‘Pallidus’ means ‘pale’….

Anterior limb of the Internal capsule: separates caudate from lentiform Caudate n. (head) nucleus

Lentiform nucleus Posterior limb of the (putamen) Internal capsule: separates thalamus Lentiform nucleus from lentiform (globus pallidus) nucleus

Thalamus

11 The basal ganglia Tips to find the basal ganglia: 1) The nucleus bulging into the lateral ventricle is the head of the caudate 2) look for the L shaped white matter (internal capsule)! 3) ‘Pallidus’ means ‘pale’….

Anterior limb of the Internal capsule: separates caudate from lentiform Caudate n. (head) Thanks! nucleus

Lentiform nucleus Posterior limb of the (putamen) Internal capsule: separates thalamus Lentiform nucleus from lentiform (globus pallidus) nucleus

Thalamus