Intro Head and Neck & Cranial Nerves PDF

INTRODUCTION TO THE HEAD & NECK REGION AND CRANIAL NERVES PROF. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  By the end of the lecture, students are required to appreciate : T...

INTRODUCTION TO THE HEAD & NECK REGION AND CRANIAL NERVES PROF. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  By the end of the lecture, students are required to appreciate : THE MAJOR STRUCTURES AND PARTS OF THE HEAD AND NECK E.g. OSTEOLOGY; MUSCLES; GLANDS; NASAL CAVITY; PHARYNX; LARYNX; ORAL CAVITY RECOGNIZE SPECIALIZATIONS IN THIS REGION OBJECTIV – COMMUNICATION (VOCAL; FACIAL; ETC) ES OF THE – SPECIAL SENSORY ORGANS FOR SMELL, VISION, HEARING & BALANCE, AND TASTE) AND LECTURE GENERAL SENSATION – FOR RESPIRATION – FOR MASTICATION AND DEGLUTITION – FOR PROTECTION OF VITAL ORGANS – FOR DEFENSE – ESPECIALLY THE LYMPHATIC SYSTEM – FOR ENDOCRINE FUNCTIONS 2/18/2025 Prof. J. AHENKORAH   The head and neck region of the body is quiet a difficult area Anatomically.  It is a relatively small area packed with very important small structures.  It is also the part associated with the proximal ends of the GIT, RESPIRATORY, SPECIAL SENSE ORGANS, VESSELS AND CRANIAL NERVES etc. 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH   THE S.C.A.L.P The soft tissue that envelop the cranial vault, extends from the Ext. occipital protuberance & Sup. Nuchal line to the supra orbital margins. NOTE: The superficial fascia of the scalp is dense, firm, has fibroadipose tissues and closely adherent to the skin and also to the underlying structures (epicranial aponeurosis) Laterally, the fascia is prolonged into the temple where it is loose in texture. See zygomatic arch 2/18/2025 Prof. J. AHENKORAH LAYERS OF THE SCALP: SKIN-(Thick), hair, numerous sebaceous glands (see: Sebaceous cyst) CONNECTIVE TISSUE-dense connective tissue (collagen fibers) attached to the outer walls of blood vessels & nerves found here. APONEUROSIS- a.k.a “GALEAL APPONEUROSIS” LOOSE AREOLAR REGION- PERIOSTEUM/PERICRANIUM “DANGER AREA” – LOOSE AREOLAR TISSUE ZONE because infections can pass into the cranial cavity through Emissary veins. The S,C, & A layers forms one unit which can pull off the loose Areolar layer. 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  Lacerations to the scalp A. Profuse bleeding B. Gapping of wounds  Cutaneous nerves like Supra orbital, Supratrochlear, Auriculotemporal, Greater, Lesser and Third Occipital supply different parts of the head. 2/18/2025 Prof. J. AHENKORAH  OSTEOLOGY SKULL – CRANIUM AND MANDIBLE – PARTS OF THE SKULL – PARTS OF THE MANDIBLE – BASE OF SKULL CERVICAL VERTEBRAE – ATLAS – AXIS – VERTEBRA PROMINENCE – OTHER REFERENCE POINTS 2/18/2025 Prof. J. AHENKORAH   The Skull is composed of 28 pieces of bones, most of them are paired. A Calvarium and a delicate facial skeleton 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  THE PTERION-see “H” FRONTAL PARIETAL BONES Frontal, Squamous Temporal, Parietal, ST Greater Wing of GWS Sphenoid. 2/18/2025 Prof. J. AHENKORAH THE PTERION  RELATION Middle Meningeal Vessels. 2/18/2025 Prof. J. AHENKORAH  Bleeding from the Middle Meningeal vessels results in an EXTRADURAL/EPIDURAL HAEMORRHAGE  CEPHALHEMATOMA?  CAPUT SUCCEDANEUM? 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  The inferior margin of the orbit and the superior margin of the external acoustic meatus of both sides of the cranium, lie in the same horizontal plane called the ORBITOMEATAL PLANE. 2/18/2025 Prof. J. AHENKORAH  Emissary veins: valveless veins which normally drain external veins of the skull into the dural venous sinuses. Diploe: soft, spongy, or cancellated substance between the plates of the skull. calvarium 2/18/2025 Prof. J. AHENKORAH  FONTANELLE? NASAL CAVITY AND PARANASAL SINUSES OSTEOLOGY OF THE NASAL CAVITY COMMUNICATIONS EXTERNAL ENVIRONMENT NASOPHARYX PARANASAL AIR SINUSES LACRIMAL APPARATUS FUNCTIONS OF NASAL CAVITY – RESPIRATION – SMELL – PROTECTION 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH Paranasal sinuses  Palate Levator veli palatini m. Tensor veli palatine m. Hard palate Soft p alate Posterior view; Coronal Section Medial view; Sagittal Section Infraorbital nerve CN V-2 Uvula Palatoglossal arch Palatine tonsils Palatopharyngeal arch Lesser palatine nerve Greater palatine nerve  THE NECK  THE NECK extends from the base of the cranium and the inferior border of the mandible to the thoracic inlet. The sup. Fascia contains a variable amount of adipose tissue and a muscle called Platysma. The deep cervical fascia is divided into INVESTING, PRETRACHEAL & PREVERTEBRAL LAYERS. These layers define a number of potential spaces, above and below the HYOID BONE. Infections can spread between the head and neck and between the tissue spaces of the face and mediastinum. These facial layers surrounds the muscles of the neck to some degrees. A condensation of the deep fascia ( Carotid sheath) surrounds the Common carotid and internal carotid arteries, internal jugular vein, vagus, and ansa cervicalis 2/18/2025 Prof. J. AHENKORAH  THE PHARYNX lecture coming up soon 2/18/2025 Prof. J. AHENKORAH  ORAL CAVITY DESIGN – FEEDING – PROTECTION – MASTICATION MUSCLES; TEMPOROMANDIBULAR JOINT (TM J); TEETH – SWALLOWING – COMMUNICATION (VERBAL AND SOCIAL) CONTENTS – TONGUE – SALIVARY GLANDS COMMUNICATION – PHARYNX – EXTERNAL ENVIRONMENT 2/18/2025 Prof. J. AHENKORAH  THE LARYNX lecture coming up soon 2/18/2025 Prof. J. AHENKORAH  THE SPINE OF C7 VERTEBRA (VERTEBRA PROMINENS) IS ESPECIALLY PROMINENT ALONG THE MIDLINE POSTERIORLY, WHEN THE NECK IS FLEXED. 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  MUSCLES OF FACIAL EXPRESSION MAJOR SOCIAL MUSCLE MUCLES OF COMMUNICATION ORBICULARIS OCULI ORBICULARIS ORIS OCCIPITALIS & FRONTALIS PLATYSMA RISORIUS ZYGOMATICUS MAJOR & MINOR MENTALIS Levator Labii Superioris alaeque Nasii ETC 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  MUSCLES OF MASTICATION TEMPORALIS MASSETER LATERAL PTERYGOID MEDIAL PTERYGOID DIGASTRIC 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  GLANDS OF HEAD AND NECK PITUITARY GLAND LACRIMAL GLAND SALIVARY GLANDS THYROID GLAND PARATHYROID GLANDS – SUPERIOR – INFERIOR MINOR SALIVARY GLANDS 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  READ ON THE ANATOMY OF THE THYROID GLAND 2/18/2025 Prof. J. AHENKORAH  LYMPHATICS OF HEAD AND NECK EXTENSIVE EVERYWHERE – EXCEPT THE BRAIN AND THE CORNEA SUPERFICIAL LYMPHATICS ring-occipital, preauricular (Parotid), Submandibular & Submental DEEP or inner ring LYMPHATICS -LYMPHATIC AGGREGATIONS – PHARYNGEAL TONSIL (ADENOIDS) – TUBAL TONSILS – LINGUAL TONSIL – PALATINE TONSILS SEE- Waldeyer’s ring CLINICAL SIGNIFICANCE – SPREAD OF CANCER CELLS 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVES 2/18/2025 Prof. J. AHENKORAH  OBJECTIVES TO BE ABLE TO IDENTIFY THE CRANIAL NERVES BE ABLE TO DIFFERENTIATE PART AND FULL FUNCTIONAL LOSS IN CRANIAL NERVES 2/18/2025 Prof. J. AHENKORAH  Thereare 12 PAIRS of cranial nerves. They are numbered using Roman numerals in a ROSTROCAUDAL SEQUENCE.  SOME ARE FUNCTIONALLY EITHER PURELY SENSORY OR PURELY MOTOR WHEREAS OTHERS ARE FUNCTIONALLY MIXED.  SOME CARRY PRE- OR POST GANGLIONIC PARASYMPATHETIC FIBRES THAT ARE SECRETOMOTOR TO SALIVARY & LACRIMAL GLANDS OR EVEN MOTOR TO SOME SMOOTH MUSCLE WITHIN THE EYEBALL. 2/18/2025 Prof. J. AHENKORAH  CN I - Olfactory n. CN II - Optic n. CN III - Oculomotor n. CN IV - Trochlear n. CN V - Trigeminal n. CN VI - Abducens n. CN VII - Facial n. CN VIII - Vestibulocochlear n. CN IX - Glossopharyngeal n. CN X - Vagus n. CN XI - Accessory n. CN XII - Hypoglossal n. 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE I OLFACTORY RESPONSIBLE FOR SMELL (SENSORY) SENSORY RECEPTORS (IN ROOF OF NASAL CAVITY) OLFACTORY TRACT TO THE BRAIN DIRECT INSTEAD OF ENDING IN THALAMUS 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  SMELL AND RELATED FUNCTIONS SOCIAL RELATIONS EMOTIONS HUNGER/APPETITE SEXUAL ATTRACTION OR REPULSION – BODY SCENT – PERFUME INDUSTRY PROTECTION (DEFENSIVE MECHANISM) SURVIVAL DETECTION OF NARCOTICS ETC (DOGS) LOSS OF SMELL AND RELATED PROBLEMS 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE II THE OPTIC NERVE VISION (SENSORY) RETINA – RECEPTORS (RODS AND CONES) – BIPOLAR NEURONS – GANGLION (MULTIPOLOAR NEURONS) OPTIC NERVE THALAMUS VISUAL CORTEX 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  VISION AND BEHAVIOR APPRECIATION:COLOUR,DEPTH,DIMENSIONS,P OSITION; HEIGHT; SPEED ETC ATTRACTION REPULSION PROTECTION/SURVIVAL INTEGRATED WITH – SMELL – SOUND – TOUCH – BALANCE ETC LOSS OF VISION 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE III: OCULOMOTOR MOTOR TO ALL EXTRAOCULAR MUSCLES, EXCEPT – LATERAL RECTUS – SUPERIOR OBLIQUE MOTOR TO EYELID MUSCLE – LEVATOR PALPEBRAL SUPERIORIS MOTOR TO INTRINSIC MUSCLES – CONSTRICTOR PUPILLAE – CILIARIS - RELAXING THE LENS 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  DAMAGE TO OCULOMOTOR EFFECT – PARALYSIS OF OCULAR MUSCLES SQUINT (STRABISMUS) DIPLOPIA – PARALYSIS OF EYELID MUSCLES DENSE PTOSIS EFFECT – DILATATION OF PUPILS – BLURRED VISION 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE IV: TROCHLEAR NERVE SUPPLY TO THE SUPERIOR OBLIQUE MUSCLE HELPS TO LOOK DOWN AND OUT DAMAGE – DOUBLE VISION – FOCUSSING DIFFICULTY – HEAD MOVEMENT TO ACCOMMODATE DEFECT 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE V: TRIGEMINAL V1 OPHTHALMIC — SKIN ABOVE LATERAL ANGLE OF EYE — CORNEA V2 MAXILLARY — BETWEEN ANGLE OF EYE AND ANGLE OF MOUTH V3 MANDIBULAR — BELOW ANGLE OF MOUTH (SENSORY) — MUSCLES OF MASTICATION (MOTOR) — OTHER MUSCLES (TENSOR VELI PALATINI; TENSOR TYMPANI; MYLOHYOID; ANTERIOR BELLY OF DIGASTRIC) 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  The parts of the adult face derived from the ophthalmic (frontonasal), maxillary and mandibular divisions of the skin of the face, showing the lines of fusion and definitive innervation. 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE VI: ABDUCENT DISTRIBUTED TO LATERAL RECTUS DAMAGE: – SQUINT (STRABISMUS) – DOUBLE VISION – BLURRED VISION 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE VII: FACIAL — (SUPERIOR SALIVARY NUCLEUS) Supply ALL EXOCRINE GLANDS OF THE HEAD , EXCEPT PAROTID GLAND — MUSCLES OF FACIAL EXPRESSION MAINLY — TASTE, ANTERIOR 2/3 OF TONGUE — – PART OF EXTERNAL EAR — DAMAGE TO FACIAL NERVE/NUCLEUS 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH CN VII – Facial Nerve Muscles of facial expression (somatic motor) Internal acoustic meatus Facial canal Stylomastoid foramen Parotid gland 5 Branches to the face T To Zanzibar By Motor Car Z T- Temporal B Z-Zygomatic Parotid gland B-Buccal M-Mandibular M C C-Cervical 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE VIII: VESTIBULO-COCHLEA – COCHLEA APPARATUS – SEMICIRCULAR CANALS HEARING BALANCE NOTE THAT THIS NERVE TRAVELS WITH FACIAL NERVE IN THE INTERNAL AUDITORY MEATUS LESION IN THIS REGION WOULD AFFECT ALL THREE NERVES (6 FUNCTIONAL COMPONENTS) 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE IX: GLOSSOPHARYNGEAL NERVE — STYLOPHARYNGEUS — (INFERIOR SALIVARY NUCLEUS) — PAROTID GLAND — VISCERAL SENSATION PHARYNX — TASTE, POSTERIOR 1/3 OF TONGUE — GENERAL SENSATION, POSTERIOR 1/3 OF TONGUE 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE X: VAGUS — DORSAL VAGAL NUCLEUS — PARASYMPATHETIC DISTRIBUTION TO NECK, THORAX; ABDOMEN UP TO PROXIMAL 2/3 OF TRANSVERSE COLON — PHARYNGEAL AND LARYNGEAL MUSCLES — VISCERAL AFFARENTS FROM REGIONS OF PARASYMPATHETIC DISTRIBUTION — TASTE TO PART OF ROOT OF TONGUE — PART OF THE EXTERNAL AUDITORY MEATUS 2/18/2025 Prof. J. AHENKORAH 2/18/2025 Prof. J. AHENKORAH CRANIAL NERVE XI: ACCESSORY NERVE COMPOSITE CRANIAL ACCESSORY (DISTRIBUTED THROUGH THE VAGUS) PALATO-GLOSSUS SOME MUSCLES OF LARYNX AND PHARYNX SPINAL ACCESSORY STERNOCLEIDOMASTOID TRAPEZIUS 2/18/2025 Prof. J. AHENKORAH  CRANIAL NERVE XII: HYPOGLOSSAL ALL MUSCLES OF THE TONGUE, EXCEPT THE PALATO-GLOSSUS – GENIO-GLOSSUS – HYO-GLOSSUS – STYLO-GLOSSUS – INTRINSIC MUSCLES OF THE TONGUE  DAMAGE: DEVIATION OF TONGUE TO THE SAME SIDE 2/18/2025 Prof. J. AHENKORAH Connexions of the four PAIRS OF parasympathetic ganglia of the head & neck. They innervate the salivary and lacrimal glands, the mucous glands of the oral and Nasal cavities & the sphincter pupillae & ciliary muscles of the eyeball. Many more preganglionic parasympathetic fibres travel in the Vagus. 2/18/2025 Prof. J. AHENKORAH  END OF LECTURE 2/18/2025 Prof. J. AHENKORAH