Brain Stem Flashcards
Location:
❑——— cranial fossa
Location:
❑posterior cranial fossa
RELATIONS
• Superiorly, midbrain continuous with ———-
• Inferiorly, medulla continuous with ————
• Posteriorly, pons & medulla separated from cerebellum
(CBM) by ———
• 4TH Ventricle continuous superiorly with ———- in Midbrain & inferiorly with ———-of spinal cord
• Midbrain, pons and medulla connected to CBM by ———, ——— and ———, respectively
RELATIONS
• Superiorly, midbrain continuous with cerebral hemisphere (CH)
• Inferiorly, medulla continuous with spinal cord (SC)
• Posteriorly, pons & medulla separated from cerebellum
(CBM) by 4th Ventricle.
• 4TH Ventricle continuous superiorly with Cerebral aqueduct in Midbrain & inferiorly with central canal (CC) of spinal cord
• Midbrain, pons and medulla connected to CBM by superior, middle and inferior cerebellar peduncles, respectively
Cranial nerves related to the brainstem
• The third and fourth nerves emerge from the surface of the ——-;
• The fifth from the ———;
• The sixth, seventh and eighth nerves emerge
at the junction of the ——— and ———;
• The ninth, tenth, eleventh and twelfth nerves emerge from the surface of the ———-.
Cranial nerves related to the brainstem
• The third and fourth nerves emerge from the surface of the midbrain;
• The fifth from the pons;
• The sixth, seventh and eighth nerves emerge
at the junction of the pons and medulla;
• The ninth, tenth, eleventh and twelfth nerves emerge from the surface of the medulla.
Functions
3 broad functions of brainstem
Functions
3 broad functions:
1. Conduit for the ascending tracts and descending tracts connecting the spinal cord to the different parts of the higher centers in the forebrain
2. Contains important reflex centers associated with the control of respiration and the cardiovascular system and with the control of consciousness
3. Contains the important nuclei of cranial nerves III through XII
MEDULLA
Divided into:
1. A lower closed part with central canal- ————
2. An upper open part posteriorly which is related to the lower part of the 4th ventricle————
MEDULLA
1. A lower closed part with central canal- SPINAL MEDULLA
2. An upper open part posteriorly which is related to the lower part of the 4th ventricle-
MEDULLA OBLONGATA
GROSS ANATOMY OF MEDULLA OBLONGATA
• ——— in shape.
• Broad part joins the —— above
• Narrow part becomes continuous with the ———-.
• Junction between medulla and spinal cord-level of Upper border of ———vertebra.
• Length ~ —cm; Width ~ —cm at Upper end.
GROSS ANATOMY OF MEDULLA OBLONGATA
• Conical in shape.
• Broad part joins the pons above
• Narrow part becomes continuous with the spinal cord.
• Junction between medulla and spinal cord-level of Upper border of Atlas (C1 vertebra).
• Length ~ 3 cm; Width ~ 2cm at Upper end.
Features on the anterior surface of Medulla Oblongata
• ———— - an upward continuation of similar fissure present on the spinal cord
• ————- on each side, in line with the ventral roots of spinal cord; attachment to rootlets of hypoglossal nerve
Features on the anterior surface of Medulla Oblongata
• Anterior median fissure- an upward continuation of similar fissure present on the spinal cord
• Antero-lateral sulcus- on each side, in line with the ventral roots of spinal cord; attachment to rootlets of hypoglossal nerve
FEATURES (Cont’d)
• ———-,an elevation on each side of midline btw ant. median fissure and antero-lateral sulcus.
Composed of bundles of nerve fibers of ———— tract that descends from the cerebral cortex to the spinal cord
• Tapers inferiorly where the majority of fibers cross over to the opposite side, obliterating the medulla, this is called————
•———- prominent, elongated oval swelling; lies in upper part of medulla posterolateral to the pyramid separated by anterolateral sulcus.
• Underlying——- nucleus.
FEATURES (Cont’d)
Pyramid
• an elevation on each side of midline btw ant. median fissure and antero-lateral sulcus.
• Composed of bundles of nerve fibers of corticospinal tract that descends from the cerebral cortex to the spinal cord
• Tapers inferiorly where the majority of fibers cross over to the opposite side, obliterating the medulla-decussation of the pyramid.
Olive
• prominent, elongated oval swelling; lies in upper part of medulla posterolateral to the pyramid separated by anterolateral sulcus.
• Underlying inferior olivary nucleus.
Features on posterior surface of medulla
oblongata
————: Upward continuation of similar fissure on spinal cord
————: in line with dorsal roots of spinal nerves; gives attachment to the rootlets of 9th, 10th and 11th cranial nerves.
Between the posterior median sulcus and posterolateral sulcus, the medulla contains tracts (asccending) that enter it from the ———— of the spinal cord.
-Fasciculus ————- lies medially and fasciculus ———- lies laterally
Both fasciculi end in rounded elevations called ———— and ———— respectively
Features on posterior surface of medulla
oblongata Posterior median sulcus-
Upward continuation of similar fissure on spinal cord
Posterolateral sulcus-
in line with dorsal roots of spinal nerves; gives attachment to the rootlets of 9th, 10th and 11th cranial nerves.
Between the posterior median sulcus and posterolateral sulcus, the medulla contains tracts (asccending) that enter it from the posterior funiculus of the spinal cord.
Fasciculus gracilis:
lies medially and fasciculus cuneatus lies laterally
Both fasciculi end in rounded elevations called gracile tubercle (nucleus gracilis) and cuneate tubercle (nucleus cuneatus) respectively
Just above these tubercles, medulla is occupied by a ———— fossa which forms the lower part of the ———.
• This fossa is bounded on each side by —————which connect the medulla to cerebellum.
Just above these tubercles, medulla is occupied by a triangular fossa which forms the lower part of the 4th ventricle.
• This fossa is bounded on each side by inferior cerebellar peduncle which connect the medulla to cerebellum.
Features on the posterior part of the
medulla that forms the floor of the 4th
ventricle
• Presents ——— sulcus, on each side of which there is a longitudinal elevation called the ————- (continuous above in the pontine part of the floor of 4th ventricle). The eminence is bounded laterally by ————.
• The sulcus limitans is marked by a depression called ———-. The part of the medulla below fovea presents ———- triangle medially and ——— triangle laterally.
• Between the vagal triangle, above and gracile tubercle, below lies a small area called ———-.
•
• The lowest part of the floor is called the————- (for its resemblance to a nib). •
• The inferior angle where the lateral margins of the floor meet is called ———.
Features on the posterior part of the
medulla that forms the floor of the 4th
ventricle
• Presents median sulcus, on each side of which there is a longitudinal elevation called the median eminence (continuous above in the pontine part of the floor of 4th ventricle). The eminence is bounded laterally by sulcus limitans.
•
• The sulcus limitans is marked by a depression called inferior fovea. The part of the medulla below fovea presents hypoglossal triangle medially and vagal triangle laterally.
• Between the vagal triangle, above and gracile tubercle, below lies a small area called area postrema.
•
• The lowest part of the floor is called the calamus
scriptorius (for its resemblance to a nib). •
• The inferior angle where the lateral margins of the floor meet is called obex.
GROSS ANATOMY OF PONS
• Pons has a convex ——— surface marked by transversely running fibers which laterally forms a bundle called ————.
• Main Features
• - The ——— nerve emerges from the anterior surface at its junction with middle cerebellar peduncle.
• - Presents a —— sulcus in the midline which lodges ——- artery
• - In the groove between Pons and the medulla oblongata, there emerge, from medial to lateral,—-,——,—- nerves.
• Posterior surface of the pons is limited laterally by ———— and forms the upper part of the floor of the———.
•
• Main Features:
• - The floor is divided into symmetrical halves by a ———
• - Lateral to this sulcus is an elongated elevation, the ———-, which is bounded laterally by a ———-.
• - Inferior end of medial eminence is slightly expanded to form
———-, which is produced by —— nerve
• - The upper end of sulcus limitans presents a bluish-gray
coloration and the area is called ———-.
• - ———- lies lateral to sulcus limitans.
GROSS ANATOMY OF PONS
• Pons has a convex anterior surface marked by transversely running fibers which laterally forms a bundle called middle cerebellar peduncle.
• Main Features
• - The trigeminal nerve emerges from the anterior
surface at its junction with middle cerebellar peduncle.
• - Presents a basilar sulcus in the midline which lodges basilar artery
• - In the groove between Pons and the medulla oblongata, there emerge, from medial to lateral, abducent, facial and vestibulocochlear nerves.
• Posterior surface of the pons is limited laterally by superior cerebellar peduncle and forms the upper part of the floor of the 4th ventricle.
•
• Main Features:
• - The floor is divided into symmetrical halves by a median
sulcus.
• - Lateral to this sulcus is an elongated elevation, the medial
eminence, which is bounded laterally by a sulcus limitans.
• - Inferior end of medial eminence is slightly expanded to form
facial colliculus, which is produced by facial nerve
• - The upper end of sulcus limitans presents a bluish-gray
coloration and the area is called substantia ferruginosa.
• - Area vestibule lies lateral to sulcus limitans.
Parts of the Pons
• · a posterior part, the ———-, and • · an anterior ——— part
Parts of the Pons
• · a posterior part, the tegmentum, and • · an anterior basilar part
GROSS ANATOMY OF MID-BRAIN
• Anteriorly, it presents two large bundles of fibers, one on each side of the midline, called ———-
• - The ———- nerve emerges from the medial aspect
of the crus of the same side
• - The crura bounds from behind the ———fossa.
• Posteriorly, the midbrain presents four rounded swellings called ———.
• - ——— and ——— colliculi one on each side
• - Each colliculus is laterally related to a ridge called———
• o ———- and ———- brachium from respective colliculi
• o Superior brachium connects the superior colliculus to ———-
• o Inferior brachium connects the inferior colluculus to ————
• o In the midline below the inferior colliculus, the ——— nerve emerges which then winds round the side of the midbrain to reach its ventral aspect.
GROSS ANATOMY OF MID-BRAIN
•
•
• Anteriorly, it presents two large bundles of fibers, one on each side of the midline, called crus cerebri.
•
• - The oculomotor nerve emerges from the medial aspect
of the crus of the same side
•
• - The crura bounds from behind the interpeduncular
fossa.
• Posteriorly, the midbrain presents four rounded swellings called colliculi.
• - Superior and inferior colliculi one on each side
• - Each colliculus is laterally related to a ridge called
brachium
• o Superior and inferior brachium from respective
colliculi
• o Superior brachium connects the superior colliculus to lateral geniculate body
• o Inferior brachium connects the inferior colluculus to medial geniculate body
• o In the midline below the inferior colliculus, the trochlear nerve emerges which then winds round the side of the midbrain to reach its ventral aspect.
Parts of the midbrain
• The midbrain comprises two lateral halves, called the ————; which is again divided into an anterior part, the ———-, and a posterior part, ——-, by a pigmented band of gray matter,———.
•
• The narrow cavity is the ———, which connects the 3rd and 4th ventricles.
• The tectum is the part of the midbrain posterior to the ———-t; it has four small surface swellings referred to previously; these are two ——— and two ——— colliculi.
Parts of the midbrain
• The midbrain comprises two lateral halves, called the cerebral peduncles; which is again divided into an anterior part, the crus cerebri, and a posterior part, tegmentum, by a pigmented band of gray matter, substantia nigra.
•
• The narrow cavity is the cerebral aqueduct, which connects the 3rd and 4th ventricles.
• The tectum is the part of the midbrain posterior to the cerebral aqueduct; it has four small surface swellings referred to previously; these are two superior and two inferior colliculi.
