Brainstem & Cranial Nerve I-VI PDF

Brainstem & Cranial Nerve I-VI DR ZAHIRRAH BEGAM MOHAMED RASHEED Department of Diagnostic Craniofacial & Bioscience  Specific Learning Outcome 1.Identify the different parts of the brainstem. 2.Identify the cranial nerves at their exit points on the brainstem. 3.Describe components,...

Brainstem & Cranial Nerve I-VI DR ZAHIRRAH BEGAM MOHAMED RASHEED Department of Diagnostic Craniofacial & Bioscience  Specific Learning Outcome 1.Identify the different parts of the brainstem. 2.Identify the cranial nerves at their exit points on the brainstem. 3.Describe components, course, important relations and distributions of cranial nerve I, II, III, IV, V, VI. 4.Explain clinical applications of the cranial nerves.  optis for canal > 7 rotundum foramen ovale Germ layers Thalamus, U hypothalamus, Digestive cerebrum & tracts brainstem Cardiac cells Hematopoietic cells Skeletal muscle & tendons Urogenital tract Bones Reproductive gonads  BRAINSTEM – a stalk-like part of the brain connecting spinal cord with the forebrain Anterior / Ventral view Posterior / Dorsal view Thalamus superior to Midbrain Pons Medulla  Midbrain – visual & auditory processing, and reflexes of voluntary movements Anterior / Ventral view Posterior / Dorsal view Tectum Structure Structure Superior colliculus Crus cerebri Inferior colliculus Nerve Nerve CN 3 – oculomotor CN 4 – trochlear nerve nerve (just below IC ) ↓ ↓ visual field visual field  Pons live nerve fibers % = cerebellum - attach to pons / so tak nampak pons Structure Structure SCP Midline shallow groove ↑ Superior cerebellar peduncle The Basilar Groove 5 MCP – limits the posterior surface (lodges the basilar ICP artery) - Median sulcus – divides the 8 7 6 Stria medullaris – marks posterior border between surface into halves Nerve pons and MO Anterolateral side pons Facial colliculus – bulging CN 5 – trigeminal (motor and formed by fibers of facial sensory) muscle in mouth - nerve looping around CN 6 (abducent nerve) Groove between pons and MO CN 6 – abducent Many hi ad a CN 7 – facial Anterior / Ventral view Posterior / Dorsal view CSF CN 8 - vestibulocochlear = Cerebrospinal finid  Medulla Oblongata * dalam Brain stem ada of variety nucleus ↳ je imerge CN3-CN12 Anterior / Ventral view Posterior / Dorsal view from Brain stem not fiber Structure ↑ Structure OLIVE – large mass of Ventral median gray matter called inferior fissure Nerve olivary & nucleus Rootlets of CN 12 (hypoglossal 12 PYRAMID nerve) – emerge from ventrolateral Le due to Fibers - So it sulcus have - bulging CN 9 (glossopharyngeal), CN 10 (vagus). CN 11 (accessory) – emerge from dorsolateral sulcus Relation: Brainstem with Ventricular System Midbrain traversed by cerebral aqueduct (aqueduct of Sylvius) >> connect 3rd ventricle with 4th ventricle Total = 4 ventricle - prominent > CS F ↓ 3rd 2nd is+ &  Pons forms the upper ½ of the 4th ventricle SCP Bounded by SCP and ICP ICP Medula oblongata Upper ½ of MO opens up & form the lower part of the 4th ventricle Central canal within lower ½ of MO continuous with central canal of spinal cord cranial nerve CN I – OLFACTORY NERVE Functional component – caries special sensory (for sense of smell) Course and distribution: · o originates from the olfactory mucosa in the roof of nasal cavity o passed through cribriform plate of ethmoid bone o to enter the olfactory bulb in the anterior cranial fossa specifi ht o - More to o travel via olfactory tract to several olfactory areas in the brain ~ nuces Subarachnoid space – filled with CSF Cribriform plate Clinical application ANOSMIA (loss of smell) May occur in: 1. Old people – due the reduction in no. of olfactory neurosensory cells 2. Trauma to cribriform plate – could lead to CSF leakage (rhinorrhea) Subarachnoid space – filled with CSF CN II – OPTIC NERVE Functional component – caries special sensory (for vision) Course and distribution: o optic tracts emerge from the lateral geniculate nucleus, located in the thalamus, from each hemisphere caraly Sop o form optic chiasm : o the nerve exits through optic canal 10F o to supply the retina -- Optic canal latrat is -  Type of fibers it carries and the course Type of fiber: Ganglionic axon Course: Nasal field of vision i. begins in retina Right temporal Left temporal visual field visual field ii. At optic chiasm dekat dengan > - sone nasal o Nasal retinal fibers desiccate to the opposite side I - Temporal retina fiber o Temporal retinal fibers remain on Nasal retina fiber ipsilateral side ↑ - Nasal retinal fiber >> iii. Fibers travel through optic tract contributes to temporal visual field (T) iv. Fibers terminate at lateral geniculate nucleus Temporal retina fibers >> contributes to nasal visual field (N) v. Fibers from lateral geniculate nucleus travel to occipital lobe Visual cortex of occipital lobe Clinical application Visual field defects > - not go through optism Right side blindness T N (lesion: section of the right optic nerve) Bitemporal hemianopsia N N (lesion: section of optic chiasm) - defect at R&L temporal vision field (T) Left homonymous hemianopsia N T (lesion: section of right optic tract) - defect at L temporal vision field (T) - defect at R nasal vision field (N)  CN III – OCULOMOTOR NERVE Functional component – somatic motor (movement of eyeballs) & visceral motor (contraction of pupil and accommodation) Course and distribution: - o emerges from nuclei in the midbrain o exits through superior orbital fissure SoF o at this point, divides into – superior division (supplies superior rectus & levator palpebrae superioris) CN III supplies all extraocular – inferior division (supplies inferior rectus, medial rectus & inferior oblique) muscles of the eyes EXCEPT: LR (lateral rectus, CN VI) & SO (superior oblique, CN IV) o Its parasympathetic distribution will enter ciliary ganglion & eventually supplies sphincter pupillae & ciliary mm. SOMATIC MOTOR (controlled by oculomotor nucleus) Superior division Ciliary ganglion VISCERAL MOTOR (PARASYMPATHETHIC) Oculomotor Medial rectus Levator palpebrae (controlled by accessory motor nucleus) nerve (III) superioris Superior rectus Sphincter pupillae Inferior oblique Superior orbital fissure Inferior division Inferior rectus  Relations of CN III with Cerebellar Artery CN III runs between SCA and PCA at the level of midbrain Forms vascular triangle with CN III Risk of compression due to aneurysm/vascular abnormality Cavernous sinus & Relation with CN III, CN IV Cavernous sinus Internal carotid artery Optic chiasm CN III CN IV Pituitary traversing through CN VI gland CN V embedded within the lateral wall ↓ Opthalmic division not Sphenoid CN V carenous sinus Maxillary division Sinus Sphenoid bone Clinical application Oculomotor nerve palsy Ptosis (drooping) of eye lid (paralysis of Levator palpebrae superioris muscle) [N4 Abducted eyeball (paralysis of medial rectus muscle) CN3 CN IV – TROCHLEAR NERVE Emerges from the posterior surface of the midbrain Pass anteriorly in lateral wall of cavernous sinus Pass through SOF Supplies the superior oblique muscle Cavernous sinus CN IV Optic chiasm Pituitary gland Sphenoid sinus Sphenoid bone Extraocular muscles & the functions https://www.youtube.com/watch?v=f_rb6FMVHPk  CN V – TRIGEMINAL NERVE Emerges from the lateral aspect of pons Trigeminal ganglion Three main divisions: 1. Ophthalmic division, CN V1 2. Maxillary division, CN V2 Zsensory 3. Mandibular division, CN V3 sensory + motor > - Functions: o sensory functions >> ophthalmic and maxillary nerves o motor & sensory functions >> mandibular nerves  1. Ophthalmic division, CN V1 Pass through supraorbital notch, originates from trigeminal ganglion in the Supraorbital nerve supplies skin of forehead & scalp middle cranial fossa 1 Frontal nerve divides into three branches: lacrimal i. frontal nerve – 2 branches E ii. lacrimal nerve Supratrochlear nerve gize iii. nasociliary nerve – 4 branches Geyebal 2 Lacrimal nerve Supplies lacrimal gland, skin & conjunctiva exit cranium via SOF into orbit SOF Ant. & Post ethmoidal nerve Sensory fibers to meninges of anterior cranial fossa Supplies upper part of nasal cavity & external nose tip Supplies sphenoid & ethmoid air cells Long ciliary nerve Supplies eyeball 3 Nasociliary nerve Short ciliary nerve Pass through common Supplies eyeball tendinous ring  originates from trigeminal ganglion in the 2. Maxillary division, CN V2 middle cranial fossa exit cranium via FORAMEN ROTUNDUM ii. Branches derived from pterygopalatine to reach pterygopalatine fossa i. Branches directly from maxillary trunk ganglion are Supply the Zygomaticofacial Zygomaticotemporal palatal Pterygopalatin nerve branches are from: nerve Supply the skin of temple e ganglion i. directly from maxillary trunk skin of face nerve ii. derived from pterygopalatine ❶ Pharyngeal Supply the nerve ganglion nasopharynx mucosa Zygomatic Infraorbital 2️⃣ nerve nerve 3️⃣ Maxillary nerve trunk Inferior orbital Foramen fissure rotundu m ❹ Lesser nerve palatine Infraorbital foramen ❷ ❸ Supply the soft plate Middle Nasopalatine Greater nerve palatine cranial fossa nerve Pterygopalatine Supply the hard plate fossa Nasopalatine nerve Posterior superior Middle 1️⃣alveolar nerve Anterior superior superior Supply the maxillary alveolar nerve alveolar sinus & molar teeth Greater palatine foramina Greater palatine nerve Supply canine nerve Lesser palatine nerve & incisor teeth Supply premolar teeth Lesser palatine foramina  3. Mandibular division, CN V3 originates from trigeminal ganglion in the middle cranial fossa exit cranium via 1. Has both sensory & motor functions FORAMEN OVALE 2. Sensory fiber has 4 branches: To reach infratemporal fossa o inferior alveolar nerve – give rise to the mylohyoid nerve (motor nerve) Sensory root o lingual nerve Mandibular nerve o auriculotemporal nerve Foramen ovale Nerve to medial pterygoid o buccal nerve 3. Motor fibers go to 8 muscles: a. 4 muscles of mastication i. Temporalis muscle Buccal mucosa ii. Masseter muscle and 2nd & 3rd molar iii. Lateral pterygoid muscle Mandibular (Ant 2/3) foramen iv. Medial pterygoid muscle b. Other muscles: Chin & lower lip i. Tensor tympani muscle Mental ii. Tensor veli palatini muscle foramen iii. Mylohyoid iv. Ant belly of digastric muscle CN VI – ABDUCENT NERVE Functional component – somatic motor Course and distribution: o emerges from pons o course through cavernous sinus lateral to internal carotid artery o exits through superior orbital fissure o to supply lateral rectus muscle Abducent nerve (CN VI) Lateral Internal carotid rectus m. Cavernous artery sinus Optic chiasm Pituitary CN VI gland 6 Sphenoid sinus Superior orbital Sphenoid fissure bone  Clinical correlation of CN VI CN VI is very near to internal carotid artery (ICA) within the cavernous sinus Prone for compression due to aneurysm of ICA in the cavernous sinus and causes paralysis of the lateral rectus muscle IN that exits through SOF Right internal squint, = CNIV due to paralysis of Lat rectus (CN6) - INVI - & effect of Med rectus (CN3) -