Features that make temporal lobe unique
- Has different cortical organisations
- 3 layered allocortex:
- Prepiriform area
- Semilunar gyrus of uncus
- Hippocampus
- 3-6 layered meso cortex: majority of limbic lobe
- Parahippocampal gyrus
- 6 layered iso cortex (neocortex)
- Superior temporal gyrus
- Middle temporal gyrus
- Inferior temporal gyrus
- Transverse temporal gyrus
- Fusiform gyrus
Clinical correlation
- This transition from more primitive to more recent cortex might explain why certain tumour and epilepsy occurs within temporal lobe
- Superior surface is the temporal operculum of the sylvian fissure, where the middle cerebral artery travels before sending off branches to almost the entire lateral surface of the brain;
- Sylvian fissure
- Frequent site for cranial aneurysms
- Most frequently adopted route in neurosurgery to approach
- the contents of the basal cisterns
- the insula
- the mesial temporal region
- the basal ganglia (transsylvian approach)
- The mesial surface of the temporal lobe is highly related to the pathogenesis of mesial temporal lobe epilepsy;
- A common location for vascular malformations (AVM and cavernomas)
- Temporal lobe being behind the sphenoid wing increases the risk of temporal lobe contusion in head trauma
The 4 temporal lobe surfaces
Basal surface
- Composed laterally to medially
- Inferior temporal gyrus
- Occipitotemporal sulcus
- Fusiform gyrus (occipitotemporal gyrus)
- Collateral sulcus
- Parahippocampal gyrus
Lateral surface
- Superior temporal gyri
- Middle temporal gyri
- Inferior temporal gyri
- Superior temporal sulci
- Inferior temporal sulci
Superior (Opercular) surface (made up of 3 parts)
- Planum polare: 16
- A depression that constitutes the
- Superior surface of the anterior portion of the temporal lobe
- Located between the
- Heschl’s gyrus posteriorly and
- Uncus antero medially
- 2 parts:
- First part
- Extends from the Heschl’s gyrus to the level of the anterior edge of the precentral gyrus
- Its main axis oriented anteroposteriorly.
- Second part
- Starts at the level of the anterior edge of the precentral gyrus, soon deviates medially like the rest of the anterotemporal structures
- Its main axis oriented lateromedially.
- Heschl's gyrus: 6 (anterior transverse temporal gyrus)
- Located anterior to the planum temporale and Heschl’s sulcus.
- Has a hump
- is fused with the superior temporal gyrus on the lateral surface
- Junction between the Heschl’s gyrus and the superior temporal gyrus usually occurs in the coronal plane at the level of the external acoustic meatus
- Medially, the Heschl’s gyrus is directed toward the pulvinar of the thalamus, and it constitutes the posterior wall of the retroinsular space
- Planum temporale:
- Composed of 2 transverse temporal gyri:
- Middle transverse temporal gyri (4)
- Posterior transverse temporal gyri (5)
- Flat area
- Triangular-shaped area with its apex pointing medially
1, cuneus (floor of the parieto-occipital fissure);
2, calcar avis;
3, lateral wall of the atrium;
4, posterior transverse temporal gyrus
5, middle transverse temporal gyrus;
6, Heschl's gyrus (anterior transverse temporal gyrus)
7, parahippocampal gyrus;
8, body of the hippocampus and fimbria;
9, dentate gyrus;
10, temporal stem (cut);
11, head of the hippocampus;
12, uncus;
13, limen insulae;
14, rhinal sulcus;
15, superior temporal gyrus;
16, planum polare
Mesial surface (looks like a foot: occipital lobe is the calcaneus, arch of the temporal lobe)
Divisions
Anterior - posterior segments
Segment | related cistern | Artery supply | Vein drainage | Average Length of Segment | Surface | Neural Composition |
Anterior | Anteriorly: proximal sylvian and carotid cisterns Posteriorly: Crural cistern | Carotid MCA AChA PCA | • Striate (red interrupted line) segments of the basal vein • Anterior peduncular (green interrupted line) segments of the basal vein | 28 mm (range, 22-38) | - Anterior-superior - Medial - Inferior | - Anterior segment of uncus - Posterior segment of uncus - Entorhinal area |
Middle | Ambient cistern | PCA | • posterior peduncular (purple interrupted line) segments of the basal vein • proximal mesencephalic (aqua interrupted line) segments of the basal vein | 20 mm (range, 15-25) | - Superior - Medial - Inferior | - Subiculum, Dentate gyrus, Fimbria - Presubiculum - Posterior parahippocampal gyrus |
Posterior | Quadrigeminal cistern | PCA | distal mesencephalic segment (yellow interrupted line) of the basal vein | 31 mm (range, 22-41) | - Anterior - Medial - Inferior | - Isthmus (anterior surface), Hippocampal tail, Crus of fornix - Isthmus (medial surface), Precuneus (inferior portion) - Lingual gyrus (anterior to calcarine point) |
Medial - lateral segments
- Has two parts in relation to the tentorial groove
- Mesial temporal lobe that is located above the tentorial groove
- Normally herniates medially to the free edge of the tentorium and is related medially to the carotid, crural, interpeduncular, and ambient cisterns
- Mesial temporal lobe that is located below the tentorial groove
- is related to the cavernous sinus
- Basilar artery
- Pituitary gland
- Supraclinoidal segment of the internal carotid artery and ophthalmic artery
- Optic nerve and sphenoid sinus
- Trochlear nerve
- Superior cerebellar artery
- Posterior bend of the cavernous carotid artery and oculomotor nerve
- Tentorial edge
- Trigeminal nerve
- V1 and trochlear nerve
- Gasserian ganglion
- V2
- Petrous apex
- V3
- Facial and superior vestibular nerves
- Petrous carotid artery
- Geniculate ganglion
- Middle meningeal artery
- Semicircular canals
Composed of structures around the mesial temporal lobe
- Extraventricular components of the mesial temporal lobe
- Intraventricular components of the mesial temporal lobe
- Parieto-occipital fissure
- Splenium of the corpus callosum
- Heschl's gyrus
- Cuneus
- Isthmus of the cingulate gyrus
- Body of the hippocampus and fimbria
- Temporal stem
- Planum polare
- Calcarine sulcus
- Anterior calcarine sulcus
- Inferior choroidal point
- Posterior segment of the uncus
- Apex of the uncus
- Anterior segment of the uncus
- Rhinal sulcus
- Can be considered an anterior continuation of the collateral sulcus
- Separates the uncus from the temporal pole.
- Bulges into the floor of the anterior third of the temporal horn
- Lingual gyrus
- Parahippocampal gyrus
Relations
Bony
- Anteriorly
- Temporal lobe related mainly to the greater wing of the sphenoid bone
- Inferiorly
- Floor of the middle fossa and the petrous bone
- Laterally
- Squamous part of the temporal bone
- Posterior
- Posterior part of the lateral temporal lobe rises more superiorly, remains beyond the limits of the squamous suture, and is related to the parietal bone
CSF
Various structures
- Optic nerve
- Internal carotid artery
- Oculomotor nerve
- Tentorial edge
- Temporal pole
- Crus cerebri
- Basal vein and anterior choroidal artery
- Remaining amygdala
- Vein draining the roof of the temporal horn, tributary of the inferior ventricular vein
- Pulvinar of the thalamus
- Parahippocampal gyrus
- Atrium
After the complete subpial removal of the temporal lobe including the amygdalohippocampectomy, the contents of the crural and ambient cisterns (covered by arachnoid membrane) come into view.
- Oculomotor nerve entering the posterior portion of the roof of the cavernous sinus
- Superior cerebellar artery
- Posterior communicating artery
- P2A segment of the posterior cerebral artery
- Origin of the anterior choroidal artery
- Basilar artery and P1 segment of the posterior cerebral artery
- Crus cerebri
- Lateral mesencephalic vein
- Cisternal segment of the anterior choroidal artery and basal vein
- Tegmentum of the mesencephalon
- Remaining amygdala
- Inferior choroidal point
- Inferior ventricular vein
- Roof of the temporal horn
- Optic nerve
- Internal carotid artery
- Oculomotor nerve
- Posterior clinoid process
- Pons
- Trochlear nerve
- Posterior cerebral artery
- Crus cerebri
- Temporal pole
- Remaining amygdala
- Pulvinar of the thalamus
Overall view of the contents of the crural and ambient cisterns (after removal of the arachnoid membrane).
- Internal carotid artery
- Oculomotor nerve
- Posterior communicating artery
- Pons
- P2A segment of the posterior cerebral artery
- Lateral mesencephalic vein
- Anterior choroidal artery
- Crus cerebri
- Tegmentum of the mesencephalon
- Inferior choroidal point
- Choroid plexus of the temporal horn
- Basilar artery (cut)
- Internal carotid artery (cut)
- Interpeduncular sulcus (between the superior and middle cerebellar peduncles)
- Superior cerebellar peduncle
- Oculomotor nerves
- Crus cerebri
- Lateral mesencephalic sulcus
- Inferior colliculus
- Tuber cinereum
- Mamillary bodies
- Superior colliculus
- Pineal gland
- Optic tract
- Lateral geniculate body
- Medial geniculate body
- Splenium of the corpus callosum
- Pulvinar of the thalamus
- Choroid plexus
All of the vascular structures have been removed to display the neural structures underneath.
- Pons
- Pontomesencephalic sulcus and vein
- Lateral mesencephalic vein
- Tegmentum of the mesencephalon
- Crus cerebri
- Anterior choroidal artery (cisternal segment)
- Anterior peduncular segment of the basal vein
- Posterior peduncular segment of the basal vein
- Posterior mesencephalic segment of the basal vein
- Inferior ventricular vein and plexal segment of the anterior choroidal artery
- Pulvinar of the thalamus
- Tail of the hippocampus
* Vein of Galen
The posterior cerebral artery and its branches have been removed to display the vascular and neural structures underneath.
Temporal stem
Composed of the
- Cortex of the transverse insular gyrus (Heschl's gyrus)
- Which crosses the limen insulae, connecting the insular cortex to the posteromedial orbital lobule.
- Roof of temporal horn: formed by internal capsule
Connections of the Temporal Lobe
- Five main types:
- Hierarchical sensory pathway
- Dorsal auditory pathway
- Polymodal pathway
- Medial (mesial) temporal pathway
- Frontal lobe projection
Made with Bullet