Download to read offline
![Anatomical considerations
• Narrow stalk.
• Ascends out of the posterior cranial fossa through
the relatively small rigid opening in the tentorium
cerebelli.
• Two important cranial nerve nuclei.
• Reflex centers (the colliculi)
• the red nucleus and substantia nigra, [influencing
motor function]
• Ascending and descending tracts](https://image.slidesharecdn.com/brainstem-191117071504/75/Brain-stem-18-2048.jpg)
Uploaded byToqeer Iqbal
Brain stem
The document provides an overview of the brain stem, which is divided into 3 main sections - the midbrain, pons, and medulla. It describes the anatomical structures and nuclei contained within each section. Key functions include automatic behaviors for survival, relay of fiber tracts between the brain and spinal cord, and housing cranial nerve nuclei III-XII. The clinical significance is also summarized, outlining various neurological deficits that can result from lesions or vascular accidents affecting different parts of the brain stem.
More Related Content
Brain stem
- 1.
- 2. Brain Stem Dr ToqeerAhmed
- 3. Brainstem: 3 majordivisions •In post cr fossa, b/w cerebrum & SC •Midbrain •Pons •Medulla
- 4. • Produces automatic behaviors necessary for survival •Gate way for all fiber tracts • Innervation of face & head • III to XII (except XI) CN nuclei • Cerebellar peduncles
- 5. GENERAL OVERVIEW Tectum • Mostposterior • Roof over ventricular system • Colliculi & medullary vela Tegmentum • Largest, most central portion • Contains reticular formation, CN nuclei, ascending tracts Basal portion Descending Tracts
- 6.
- 7. • Rostral topons and caudal to the diencephalon • Connects pons and cerebellum with forebrain • Shortest part of brain stem (abt 2cm in length)
- 8. Posterior view Corpora quadrigemina •Roundedeminences •Colliculi •Tuber cinerium Trochlear nerves wind around the lateral aspect of the midbrain to enter cavernous sinus.
- 9. The colliculi Large nucleiof gray matter, lying beneath the corresponding surface elevation. Superior colliculi • Larger and darker • Connected to Lateral Geniculate Body (LGB) • Control reflex movements of the eyes, head and neck in response to visual stimuli Inferior colliculi • Connected to Medial Geniculate Body (MGB) • Control reflex movements of the head, neck, and trunk in response to auditory stimuli Cruciform sulcus
- 10. Lateral viewSuperior andinferior Brachia ascending in anterolateral direction Geniculate Bodies • Small, oval swellings projecting from the thalamus. • Consists axons of the optic tract/ auditory. Lateral geniculate body Medial geniculate body Inferior brachium & colliculus Superior brachium & colliculus
- 11.
- 12. • Midbrain 3Dmodels - Sketchfab.html
- 13. Internal structureCerebral aqueduct •linedby ependyma & surrounded by the central gray matter Tectum •Colliculi Cerebral peduncle •Tegmentum •Crus cerebri •Substantia Nigra •Interpeduncular fossa
- 14. Transverse Sections Cavity, Nuclei,Tracts (motor/sensory) Superior Colliculus Inferior Colliculus Sup Colliculus M.N nucleus CN: 5 Occulomot or Nerve & Nucleus Red Nucle us Red Nucle us Sub NSub N Crus Cerebri Crus Cerebri TP FP C Spinal C Bulb Leg Head Arm MLF R S T Trigeminal Spinal & Medial Leminisci Inf Colliculus Trochlear Nerve & Nucleus Lateral, Trigeminal Spinal & Medial Leminisci Sup. C.P IPF
- 15. The Red Nucleus Reddish,Rounded mass of gray matter in tegmentum – Vascularity – An iron-containing pigment in cytoplasm of many neurons. Afferent fibers Cerebral cortex, Cerebellum, thalamus, SN & spinal cord. Efferent fibers Spinal cord, Reticular formation & thalamus
- 17.
- 18. Anatomical considerations • Narrowstalk. • Ascends out of the posterior cranial fossa through the relatively small rigid opening in the tentorium cerebelli. • Two important cranial nerve nuclei. • Reflex centers (the colliculi) • the red nucleus and substantia nigra, [influencing motor function] • Ascending and descending tracts
- 19. Oculomotor nucleus • Ipsilateralparalysis of the extra ocular muscles • Parasympathetic nucleus --- dilated pupil with absent light reflex. Trochlear nucleus • Contralateral paralysis of the sup oblique. Blockage of the Cerebral Aqueduct • Tumor
- 20. Vascular lesions Weber’s syndrome Contralateralhemiplegia of the limbs, face & tongue ---crus cerebri Ipsilateral deficits in eye motor activity -- oculomotor nerve Benedikt syndrome Contralateral hemi anesthesia---Medial lemniscus Involuntary movements of contralateral limbs---- Red nucleus
- 21.
- 22. Gross Anatomy • “Bridge“connecting both cerebellar hemispheres • 1 inch (2.5 cm) long Anterior Surface • Convex from side to side • Many transverse fibers converging on each side ---the middle cerebellar peduncle. • The basilar groove Anterolateral Surface • CN 5,6,7,8
- 23. Posterior surface • Hidden,triangular • Forms Upper half of the floor of the 4th ventricle • Limited laterally by the superior cerebellar peduncles • Median sulcus. • Medial eminence (Lateral elongated elevation, bounded laterally by the sulcus limitans • Facial colliculus – Expanded inferior end of the medial eminence (root of CN: 7 • Substantia ferruginea – Bluish grey floor of the superior part of the sulcus limitans • Area vestibuli – Lateral to the sulcus limitans – underlying vestibular nuclei
- 24. Transverse Section atlevel of Fascial Colliculus Transverse Section at level of Trigeminal Nuclei Fourth Ventricle Sup. Med velum Motor & Sensory nuclei CN:V Pontine Nuclei Trapezoid body Transverse pontine Corticospinal, corticonuclear fibers MLF RF Spinal, Lateral, Medial Leminisci Sup. Cerebellar Peduncle Mid. Cerebellar Peduncle Sup. Med velum 4thVent Pontine nuclei Facial, abducent Nuclei & nerves Med Vestibular N CN:V Nucleus & Spinal tract MLF Cerebellar peduncles
- 25. Clinical significance • Sensoryand motor nuclei of 5th, 6th, 7th & 8th cranial nerve. • Respiratory nuclei: – Apneustic & pneumotaxic centers work w/ the medulla to maintain respiratory rhythm • Cerebellar peduncles to/from the cerebellum • Ascending, descending, and transverse tracts that interconnect other portions of the CNS
- 26. Medial pontine syndrome(Paramedian pontine)
- 27. Lateral Pontine Syndrome (Circumferential Pontine) 1. Ataxia----cerebralpeduncles 2. Ipsilateral pain and temperature deficits from face----spinal trigeminal nucleus and tract
- 28.
- 29. Gross Appearance Spino-medullary junction •Foramen magnum (at the origin of roots of the 1st cervical spinal nerve) • Lower part closed around central canal • Upper open part related to lower part of 4th ventricle • Connects the pons superiorly with the spinal cord inferiorly. • Conical shape, its broad extremity directed superiorly • 3cm X 2cm at its widest part
- 30. Ventral Aspect CN XII IX,XI X • Olives •Posterolateral to the pyramids • oval elevations (inferior olivary nuclei) • Inferior cerebellar peduncles • Posterior to olives • Connect the medulla to the cerebellum. • Anterior median fissure • Pyramids • Corticospinal fibers originating in precentral gyrus • Taper inferiorly (decussation)
- 31. Posterior Surface • Superiorhalf forms the lower part of the floor of the fourth ventricle. • Inferior half – Posterior median sulcus. • Gracile tubercle---- gracile nucleus. • Cuneate tubercle---cuneate nucleus.
- 32. Internal Structure 1. Levelof the olives – across the inferior part of the fourth ventricle 2. Level of decussation of lemnisci – The great sensory decussation. 3. Level of decussation of pyramids – The Great motor decussation
- 33. Level of theOlives Inf. Medullary Valum Vestibulo-cochlear Nuclear Complex Medial, Inf. V Ant, Post. Ch Olivary Nuclear Complex Dorsal acc, Inf, Medial acc Hypoglossal Nucleus & Nerve PyramidsArcuate nuclei Ant. Median Fissure Olive Medial Leminiscus Tectospinal tract Lat. Spinothalamic tract Ant. Spinocerebellar Tract N. Ambiguus Spinal N & Tract of CN:VRet formation N. Tractus Solitarius Dorsal Vagal Nucleus & Nerve MLF 4th V ICP ICP
- 34. Nucleus Ambiguus Large motor neurons, situateddeep within the reticular formation. The emerging nerve fibers join the CN IX, X and cranial part of CN XI and are distributed to voluntary skeletal muscle.
- 35. Level of Decussationof Lemnisci Nucleus Gracilis & Cuneatus Fasciculus Gracilis & Cuneatus Spinal Nucleus & Tact CN:V Spinal Root CN:XI Inferior Olivary Nucleus Hypoglossal Nucleus & Nerve PyramidsDecussation Medial Leminisci (b/w pyramids & central GM) Post. Spinocerebellar tract Lat. Spinothalamic tract Ant. Spinocerebellar tract Medial Longitudinal Fasciculus Central Canal
- 36. Level of Decussationof Pyramids Nucleus Gracilis & Cuneatus Fasciculus Gracilis & Cuneatus Spinal Nucleus & Tact CN:V Spinal Root CN:XI MLF Acc. Olivary Nucleus Pyramid Central Canal Post. Spinocerebellar Tract Lat. Spinothalamic Tract Ant. Spinocerebellar Tract Lat. Corticospinal tract with Decussation of Pyramids
- 37. Clinical significance • Nucleiof CN: 9, 10, 11 , 12 • Ascending & Descending tracts • Respiratory centers • Herniation – d.t increased I/C pressure – Headache, neck stiffness, paralysis of last four CN – Arnold-Chiari malformation (congenital)
- 38. Medial Medullary Syndrome (Anterior Spinal Artery) inferior alternatinghemiplegia 1. Contralateral hemiplegia ---- pyramids or the corticospinal fibers 2. Contralateral loss of position sense, vibratory sense and discriminative touch---- medial leminiscus 3. Ipsilateral deviation and paralysis of the tongue---- hypoglossal nucleus or nerve
- 39. Lateral Medullary/ Wallenberg’sSyndrome (PICA) • Vertigo, nausea and vomiting----vestibular nuclei • Ipsilateral Hornor’s syndrome, (meiosis, ptosis, decreased sweating)---descending hypothalamospinal tract
- 41.