MIDBRAIN

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Q.1 What are the subdivisions of the midbrain?

• Crus cerebri,
• Substantia nigra,
• Tegmentum and
• Tectum and its cavity, cerebral aqueduct.
  
  

Q.2 What is tectum?

It is the posterior part of the midbrain. It is made up of 4 colliculi, a pair of superior and a pair of inferior.

Q.3 What are the characteristic features of substantia nigra?

It is a lamina of grey matter, made of deeply pigmented nerve cells. Afferents are from the motor cortex and collaterals of sensory tracts. Efferents pass to the corpus striatum and tegmentum.

Q.4 What are the contents of crus cerebri?

• Middle 2/3: Pyramidal tract
• Medial 1/6: Frontopontine fibers
• Lateral 1/6: Temporopontine, parietopontine and occipitopontine fibres.
  
  

Q.5 What are the connections and functions of superior colliculus?

Connections:

Afferents:
From retina (visual),
Spinal cord (Tactile),
Inferior colliculus (Auditory),
Occipital cortex (Modulating).

Efferents:
To retina,
Spinal cord (Tectospinal),
Brain stem nuclei, Tegmentum.

Function:
Control reflex movements of eyes, head, and neck in response to visual stimuli.

 

HINDBRAIN

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Q.6 What are the subdivisions of the hindbrain?

• Metencephalon, made up of pons and cerebellum.
• Myelencephalon, made up of the medulla oblongata. 

Fourth ventricle is the cavity of the hindbrain.

 Q.7 What are the constituents of the brainstem?

• Midbrain,
• Pons and
• Medulla.
  
  

Q.8 Which cranial nerves are attached to the brainstem?

• Third and fourth nerves emerge from the surface of the midbrain.
• Fifth nerves emerge from the pons.
• Sixth, seventh, and eighth nerves emerge at junction of pons and medulla.
• Ninth, tenth, eleventh, and twelfth nerves emerge from the surface of the medulla.
  
  

Q.9 Name the cranial nerve nuclei in the pons.

• Skin nerve nucleus
• Seventh nerve nucleus
• Vestibular and cochlear nuclei
• Main sensory nucleus, motor nucleus, and spinal nucleus of the trigeminal nerve.
  
  

Q.10 What are the connections and functions of the reticular formation of the brainstem?

It is connected to all parts of the nervous system directly or indirectly. It receives impulses from the motor and other areas of the cerebral cortex and relays them to the spinal cord by lateral and medial reticulospinal tract. It is also connected to the cerebellum and thalamus. Fibers to the thalamus constitute an ascending reticular activating system.

Functions:

• Involved in fine control of movements.
• Influences conduction through somatosensory, visual, and auditory pathways.
• Regulation of respiratory and cardiovascular control.
• Controls activity of adenohypophysis and neurohypophysis through the hypothalamus.
• Control of the pineal body.
• Through ascending reticular activating system maintains a state of alertness.
  
  

Q.11 What is the medial longitudinal bundle?

Association tract, which coordinates movements of eyes, head, and neck in response to stimulation of the 8th cranial nerve. The nuclei of the 3rd, 4th, 5th, 6th, and 11th cranial nerve are interconnected by the bundle.

Q.12 What is the effect of the unilateral lesion in the lower part of pons?

Crossed or alternate hemiplegia, i.e. paralysis of face on one side and limbs on the other side.

Q.13 Name the lobes of the cerebellum.

• Anterior lobe,
• Middle lobe and
• Flocculonodular lobe
  
  

Q.13.1 What is vermis and what are its parts?

It joins the two cerebellar hemispheres.

Parts:

• Lingula
• Central lobule In anterior lobe
• Culmen
• Declive
• Folium
• Tuber
• Pyramid 
• Uvula
• Nodule: In flocculonodular lobe.
  
  

Q.14 What are phylogenetic divisions of the cerebellum?

Archicerebellum: Oldest.
Flocculonodular lobe and lingula.

Paleocerebellum: Anterior lobe minus lingula. Pyramid and uvula of middle lobe

Neocerebellum: Middle lobe minus pyramid and uvula.

Q.15 Name the contents of the superior cerebellar peduncle.

Afferent tracts (Fibres entering the cerebellum):
- Anterior spinocerebellar
- Superior spinocerebellar

Efferent tracts (Fibres leaving the cerebellum):
- Cerebellorubral
- Cerebellothalamic
- Cerebelloreticular (Partly from the dentate nucleus and partly from the fastigial nucleus).

Q.16 Name the contents of the inferior cerebellar peduncle.

Afferent:

• Posterior pontocerebellar
• Cuneocerebellar
• Olivocerebellar
• Parolivocerebellar
• Reticulocerebellar
• Vestibulocerebellar
• Anterior external arcuate

Efferent:

• Cerebellovestibular
• Cerebelloolivary
• Cerebelloreticular.
• Some cerebellospinal and cerebellonuclear.
  
  

Q.17 What are the contents of the middle cerebellar peduncle?

Afferent: Pontocerebellar.

Q.18 Name the cranial nerve nuclei in the floor of the fourth ventricle.

• Hypoglossal nucleus
• Dorsal nucleus of the vagus
• Nucleus of tractus solitarius
• Inferior and medial vestibular nuclei.
  
  

Q.19 How the lateral wall of the fourth ventricle is formed?

• Upper part: Superior cerebellar peduncle.
• Lower part: Inferior cerebellar peduncle and Gracile and cuneate tubercles.
  
  

Q.20 How the floor of the fourth ventricle is formed?

By

• Posterior surface of pons
• Posterior surface of the upper part of the medulla.
  
  

Q.21 What is the effect of lesion in medulla oblongata?

The medulla contains the vital centers, i.e. respiratory, cardiac and vasomotor center. The lesion in the medulla will lead to the failure of vital functions especially, respiratory failure.