1. GROSS ANATOMY OF THE BRAIN
Dr. G.R. Leichnetz

2. Craniectomy Exposes the Dura Mater
The dura mater is the outermost of the connective tissue coverings of the brain, the meninges. It is firmly attached to the inside of the skull, and its outer layer actually constitutes the periosteum of the inside of the skull. Thus, there is no epidural space in the cranium.
The dura mater is supplied by branches of the middle meningeal artery.

3. Supratentorial Compartment- contains cerebrum
The inner layer of the dura mater gives rise to partitions (dural reflections) that create two major compartments in the cranial cavity. The falx cerebri separates the two cerebral hemispheres. The tentorium cerebelli forms a roof over the posterior cranial fossa, separating its contents (cerebellum & brainstem) from the occipital lobes of the brain.
Contains the cerebrum
Falx cerebri
Contains the cerebellum & brainstem
Tentorium cerebelli
Supratentorial Compartment- contains cerebrum
Infratentorial Compartment (Posterior fossa)- contains cerebellum and brainstem
Posterior fossa

4. When the dura mater is reflected it reveals the “leptomeninges” (arachnoid membrane + pia mater). The arachnoid is attached to the pia by arachnoid trabeculae. The space between the arachnoid and pia is the subarachnoid space.
The subarachnoid space contains CSF which is reabsorbed into the systemic circulation thru arachnoid villi which project into the superior sagittal sinus.
The cerebral arteries and veins run on the surface of the pia mater on the floor of the subarachnoid space.
Arachnoid villi

5. The surface of the cerebrum has gyri separated by sulci (grooves).
The cerebrum has five lobes: frontal, parietal, temporal, occipital, and insular.
The central sulcus separates the frontal and parietal lobes (note two vertical gyri, pre- and post-central).
The lateral sulcus separates the frontal & parietal lobes from the temporal lobe.
Parietal Lobe
Frontal Lobe
Occipital Lobe
Temporal Lobe
Insular Lobe

6. Cerebral Hemisphere Lateral Aspect
Central sulcus
Parietal Lobe
Frontal Lobe
Occipital Lobe
Temporal Lobe
Lateral sulcus
Pre-occipital notch

7. Opening the lateral sulcus reveals the insular lobe.
Superior transverse temporal gyri (Primary Auditory Cortex)
Insular Lobe
Opening the lateral sulcus reveals the insular lobe.
Insular Lobe

8. Lateral Aspect: Frontal Lobe
Precentral gyrus
Central sulcus
Superior frontal gyrus
Pars opercularis, inferior frontal gyrus
Middle frontal gyrus
Inferior frontal gyrus
Pars triangularis, inferior frontal gyrus
Pars orbitalis, inferior frontal gyrus

9. Lateral Aspect: Parietal Lobe
Postcentral gyrus
Central sulcus
Superior parietal lobule
Intraparietal sulcus
Inferior parietal lobule
Angular gyrus
Supramarginal gyrus
Lateral sulcus

10. Lateral Aspect: Temporal Lobe
Superior temporal sulcus
Lateral sulcus
Superior temporal gyrus
Middle temporal gyrus
Inferior temporal gyrus

11. Ventral (Inferior) Aspect
Frontal lobe
Diencephalon (hypothalamus)
Temporal lobe
Midbrain
Pons
Medulla
Cerebellum
The brainstem (midbrain, pons, medulla) and cerebellum occupy the posterior cranial fossa.

12. Inferior Aspect, Frontal Lobe
Olfactory bulb
Orbitofrontal gyri
Olfactory tract

13. Inferior Aspect: Temporal Lobe
Middle temporal gyrus
Parahippocampal gyrus
Parahippocampal gyrus
Uncus
Midbrain
Uncus
Occipitotemporal (fusiform) gyrus
Modified From: Haines
Inferior temporal gyrus

14. Medial Aspect/ Cerebral Hemisphere (Mid-Sagittal Section)
Central sulcus
Parietooccipital sulcus
Parietal
Frontal
Occipital
Cerebellum
Brainstem
The central sulcus and parietooccipital sulcus are used to delineate lobes on the medial aspect of the hemisphere.

15. Medial Aspect: Frontal & Parietal Lobes
Central sulcus
Paracentral lobule
Precuneus
Superior frontal gyrus
Cingulate gyrus
Corpus callosum
Parietooccipital sulcus

16. Medial Aspect: Occipital Lobe
Parietooccipital sulcus
Cingulate gyrus
Precuneus
Splenium, corpus callosum
Cuneus gyrus
Lingual gyrus
Calcarine fissure
Cerebellum

17. Midsagittal Aspect Paracentral lobule Cingulate gyrus Cerebellarvermis
Parietooccipital sulcus
Cingulate gyrus
Cuneus gyrus
Corpus callosum
Thalamus
Septum pellucidum
Hypothalamus
Midbrain
Cerebellarvermis
Calcarine sulcus
IVth vent
Pons
Medulla

18. Mid-Sagittal: Closeup
Pineal gland
Septum pellucidum
Fornix
Thalamus
Anterior commissure
Superior colliculus
Inferior colliculus
Hypothalamus
Midbrain
Optic chiasm
Mammillary body
Pons
Pituitary stalk (infundibulum)

19. Mid-Sagittal: Ventricular System
Massa intermedia
Lateral ventricle
Fornix
Pineal gland
Choroid plexus thru interventricular foramen of Monro
Cerebral aqueduct
Anterior commissure
Midbrain
Fourth ventricle
Lamina terminalis
Lateral Recess & Foramen of Luschka
Pons
Third ventricle

20. Cerebellum: Anterior (Superior) Aspect
Lateral hemisphere
Posterior Lobe
Vermis
Primary Fissure
Anterior Lobe
Midbrain

21. Cerebellum, Posterior View
Vermis
Pyramis
Posterior Lobe Hemisphere
Uvula
Tonsils of cerebellum
Medulla
Foramen of Magendie (opening in post. medullary velum from 4th ventricle)

22. Cerebellar Vermis Primary fissure Anterior lobe vernis
Flocculus- hemispheric portion of the flocculonodular lobe of the cerebellum
Fourth ventricle
Posterior lobe vermis
Nodule (vermal portion of the F-N lobe)
Prenodular fissure
Tonsil

23. Cerebellar Peduncles
The cerebellar peduncles connect the cerebellum to the three divisions of the brainstem:
SCP to midbrain
MCP to pons
ICP to medulla.
They carry major tracts into and out of the cerebellum.
Anterior lobe hemisphere removed to reveal peduncles
Superior cerebellar peduncle
Midbrain
Middle cerebellar peduncle
Pons

24. Ventral (Inferior) Aspect of the Brain
All cranial nerves exit from the ventral aspect of the brain, except the trochlear nerve.
Telencephalon- I Diencephalon- II
From the brainstem:
Mesencephalon- III, IV Metencephalon- V Myelencephalon- VI, VII, VIII, IX, X, XI, XII

25. Brainstem: Ventral Aspect Cranial Nerves
Optic (II)
Oculomotor (III)
Trigeminal (V)
Facial (VII) and Vestibulocochlear (VIII)
Glossopharyngeal (IX) & Vagus (X) Nerves

26. Ventral Aspect: Diencephalon & Midbrain
Optic Nerve
Optic Chiasm
Oculomotor Nerve (CN III)
Optic Tract
Tuber cinereum and pituitary stalk
Trochlear Nerve (CN IV)
Cerebral peduncle
Mammillary bodies

27. Ventral Aspect: Brainstem, Pons & Medulla
Trigeminal Nerve (CN V)
Middle cerebellar peduncle
Pons
Abducens Nerve (CN VI)
Medulla
Vestibulocochlear Nerve (CN VIII)
Glossopharyngeal (IX) and Vagus (X) Nerves
Facial Nerve (CN VII)
Hypoglossal Nerves (CN XII)
Spinal Accessory Nerve (CN XI)
Olive
Pyramid
Pyramidal Decussation

28. Dorsal Aspect of the Brainstem (with cerebral cortex and cerebellum removed)
Thalamus
Thalamus
Midbrain
Midbrain
Pons
Rhomboid fossa
Medulla
Barr

29. The floor of the fourth ventricle is the rhomboid fossa.
Superior colliculus
The roof of the midbrain is the tectum. It contains four elevations, the corpora quadrigemina. (superior & inferior colliculi)
Inferior colliculus
Anterior medullary velum
Superior cerebellar peduncle
The floor of the fourth ventricle is the rhomboid fossa.
The “rhomboid” can be divided into two triangles. The rostral triangle is over the pons. The caudal triangle is over the medulla.
Pons
Middle cerebellar peduncle FC
Medulla
Obex

30. Dorsal Aspect of the Medulla
Obex
Gracile tubercle
Cuneate tubercle
Fasciculus graciclis
Tuberculum cinereum
Fasciculus cuneatus
Dorsal intermediate sulcus