INTRODUCTION TO BRAIN & BRAINSTEM. 28. April.2014 Monday. Kaan Yücel M.D., Ph.D . The brain (encephalon) is divided into three major divisions. 1) Hindbrain ( Rhombencephalon ) I. Medulla oblongata II. Pons III. Cerebellum Pons and cerebellum are called as metencephalon .
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1) Hindbrain (Rhombencephalon)
I. Medulla oblongata
Pons and cerebellum are called as metencephalon.
2) Midbrain (Mesencephalon)
3) Forebrain (Prosencephalon)
I. Telencephalon (Cerebrum)
II. Diencephalon (between brain)
oldest part of the CNS.
medulla oblongata, pons, and midbrain
occupies the posterior cranial fossa of the skull.
stalklike in shape and connects the narrow spinal cord with the expanded forebrain.
contains 10 cranial nerves, and most of the motor and sensory systems pass through this important region.
a relatively small region (approximately 7 cm long)
links the forebrain (i.e., cerebral cortex) and spinal cord and all messages going between the two areas must go through the brain stem.
2 cm in length
connects the pons and cerebellum with the forebrain.
cerebral hemispheres connected to brainstem by 2 large fiber tracts cerebral peduncles
The dorsal aspect of the midbrain the tectum(L., roof]
paired superior and inferior colluculi(singular, colliculus).
superior colliculicenters for visual reflexes
inferior colliculilower auditory centers
Tegmentum: Anteriorpart of midbrain
The midbrain comprises two lateral halves
anterior part: crus cerebri
posterior part: tegmentum
Nuclei of 12 cranialnerves
10 of them in thebrainstem
Of the IV & III
Of theother 4
Of thelast 4
II Optic SensoryRetinal ganglion cells
III OculomotorMainly motorMidbrain
Eye movements & pupillary reflex
Intorts the eyeball.
V TrigeminalBoth sensory and motorPons
Receives sensation from the face and innervates the muscles of mastication.
VI AbducensMainly motorPons
Abducts the eye.
Provides motor innervation to the muscles of facial expression.
Receivesthe special sense of taste from the anterior 2/3 of the tongue and provides secretomotor innervation to the salivary glands (except parotid) and the lacrimal gland.
VIII VestibulocochlearMostly sensoryPons
Hearing and balance
IX Glossopharyngeal Both sensory and motorMedulla
Receives taste from the posterior 1/3 of the tongue, provides secretomotor innervation to the parotid gland, and provides motor innervation to the stylopharyngeus. Some sensation is also relayed to the brain from the palatine tonsils.
Innervationto most laryngeal and pharyngeal muscles (except the stylopharyngeus, which is innervated by the glossopharyngeal).
Parasympatheticfibers to nearly all thoracic and abdominal viscera till the proximal two-thirds of the transverse colon.
Receives the special sense of taste from the epiglottis.
A major function: controls muscles for voice and resonance and the soft palate.
XI Accessory (often separated into the cranial accessory and spinal accessory nerves) Medulla
Mainly motor Cranial and Spinal Roots
Controls the sternocleidomastoid and trapezius muscles, and overlaps with functions of the vagus nerve (CN X). Symptoms of damage: inability to shrug, weak head movement.
XII Hypoglossal mainly motor Medulla
Provides motor innervation to the muscles of the tongue (except for the palatoglossus, which is innervated by the vagus nerve) and other glossal muscles. Important for swallowing (bolus formation) and speech articulation.
More than 100 nuclei scattered throughout the tegmentum of the midbrain, pons and medulla have been identified as being part of the brainstem reticular formation.
1- The regulation of the level of consciousness, and ultimately cortical alertness
2- The control of somatic motor movements
3- The regulation of visceral motor or autonomic functions
4- The control of sensory information
Anatomicaldifferences, differences in the neurotransmitters, differences in the physiologic effects
The autonomic nervous system and the endocrine system control the internal environment of the body.
The various activities of the autonomic and endocrine systems are integrated within the hypothalamus.
prepares and mobilizes the body in an emergency, when there is sudden severe exercise, fear, or rage.
aims at conserving and storing energy,
in the promotion of digestion and the absorption of food by increasing the secretions of the glands of the gastrointestinal tract and stimulating peristalsis.