Plexus Cervicalis

Block 2: Head and Neck Lecture 11: Skull, Scalp, Superficial Face and Neck • Bones, sutures, landmarks of the skull o Skull/cranium, calvaria, neurocranium, viscerocranium o Cranial sutures: immovable, fibrous joints between two bones of the skull  Coronal, Sagittal, Lambdoid, Metopic (inconstant)  Pterion: fracture is life threatening because middle meningeal artery can be ruptured leading to epidural hemorrhage  Newborn fontanelles • Layers of the scalp o Skin, connective tissue, aponeurosis (galea aponeurotica), loose connective tissue, pericranium o Scalp lacerations  profuse bleeding and gaping wounds if aponeurosis is cut o Dangerous area: loose connective tissue facilitates transmission of infection (emissary veins to interior of cranial cavity) • Muscles of facial expression: motor innervated by Facial Nerve, sensory innervated by branches of Trigeminal Nerve o Muscles of mastication (temporalis, masseter and medial/lateral pterygoids) motor innervated by CN V3 o Bell’s palsy (peripheral lesion of facial nerve): facial muscle paralysis, cannot close eyelids, angle of mouth droops, forehead does NOT wrinkle o Trigeminal neuralgia: intermittent excruciating pain in V2 o Thrombophlebitis of the facial vein (danger triangle): communication of facial vein with cavernous sinus facilitates spread of infection from superficial face to inside of cranial cavity • Structures of external, middle ear Lecture 12: Introduction to Cranial Nerves Cranial Nerve Function Route thru skull I (olfactory) Smell Cribiform plate (ethmoid bond) II (optic) Sight Optic canal III (oculomotor) Move eyeball Superior orbital fissure IV (trochlear) Move eyeball Superior orbital fissure V (trigeminal) Sensory: face V1: superior Move jaw orbital fissure V2: foramen rotundum V3: foramen ovale VI (abducent) Move eyeball Superior orbital fissure VII (facial) Move face, taste Internal acoustic from front of meatus tongue VIII Hear, balance Internal acoustic (vestibulocochlear) meatus IX Taste from back Jugular foramen (glossopharyngeal) of tongue, move stylopharyngeus X (vagus) Tons of stuff Jugular foramen XI (accessory) XII (hypoglossal)

Move sternocleidomast oid and trapezius Move tongue

In thru foramen magnum, out thru jugular foramen Hypoglossal canal

Structures innervated

Eye muscles (except SO and LR) Superior oblique V1: scalp V2: cheek, nose V3: chin, muscles of mastication Lateral rectus Facial muscles, tongue

Injury Anosmia, rhinorrhea Blindness Eyeball is down and out, eyelid droop, dilated pupil Inability to look down when eyeball in towards nose Loss of sensation, chewing

Medial strabismus (eye turns towards nose) Bell’s palsy, loss of taste Hearing, balance problems

Stylopharyngeus, tongue

Problems swallowing, speech difficulty

Lots of muscles in throat/voicebox Sternocleidomastoid, trapezius

Big problems…

Intrinsic tongue muscles,

Tongue sticks out sideways

Can’t raise shoulders, turn head

extrinsic tongue muscles except palatoglossus Autonomic function of Cranial Nerves Oculomotor nerve: Edinger-Westphal nucleus  ciliary ganglion  short ciliary nerves  Sphincter pupillae: pupil constriction, ciliary muscles: lens accommodation Facial nerves: Superior salivatory nucleus  nervous intermedius to petrosal nerve  pterygopalatine ganglion  zygomaticotemporal nerve to lacrimal nerve  lacrimal gland: tearing Superior salivatory nucleus  nervous intermedius to chorda tympani  submandibular ganglion  submandibular/sublingual salivary glands: salivation Glossopharyngeal: Inferior salivatory nucleus  lesser petrosal nerve  otic ganglion  auriculotemporal nerve  parotid gland: salivation Lecture 13: The Cranial Cavity • Meninges o Dura mater  Venous sinuses o Arachnoid mater o Pia mater • Intracranial hemorrhages o Epidural (arterial) o Subdural (veinous) o Subarachnoid (Circle of Willis) o Cerebral (intracerebral) • Cerebrospinal fluid = support for brain, blood vessels, nerves o Site of secretion: choroids plexus o Circulation o Hydrocephalus: increased CSF volume leading to pressure on brain (communicating and non-communicating) o Lumbar puncture • Circle of Willis • Anterior cranial fossa o Frontal bone, ethmoid bone, sphenoid bone o Foramen cecum, olfactory foramina, crista galli • Middle cranial fossa o Sphenoid bone, temporal bone, parietal bone o Optic canal, superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosum, foramen lacerum • Posterior cranial fossa o Sphenoid bone, temporal bone, occipital bone, parietal bone o Internal acoustic meatus, jugular foramen, foramen magnum, hypoglossal canal Lecture 14: The Orbit Axes of orbits diverge at approximately 45 degrees but optical axes are parallel • Eyelids o Skin, muscle, tarsal plates/orbital septum, conjunctiva o Conjunctivitis: common cause of painful red eye, mucopirulent discharge, itching and swelling • Eyeball o Lens  Cataract: cloudy lens, treated with surgical extraction o Anterior cavity: contains aqueous humor o Posterior cavity: contains vitreous humor o Fibrous tunic

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 Sclera, cornea= major refractive structure (avascular) o Vascular tunic  Choroid, ciliary body  Glaucoma: problem with resorption  pressure  blindness  Iris Lacrimal apparatus Blood vessels (arteries via the internal/external carotid artery) Autonomic innervation Clinical testing of extraocular muscles Injuries leading to disorders of eye movement o Oculomotor nerve injury: ptosis, lateral strabismus, pupil dilation o Trochlear nerve injury: inability to look down and nasally (leads to head tilt) o Abducent nerve injury: medial strabismus o Facial nerve injury: loss of lacrimation (dry cornea) o Sympathetic fiber injury: Horner’s Syndrome, miosis, ptosis, anhydrosis, erythematosis

Lecture 15: Temporal, Infratemporal and Pterygopalatine Fossae • Temporal fossa o Contains temporalis muscle • Infratemporal fossa o Inferior to zygomatic arch, posterior to upper jaw o Contains medial/lateral pterygoid muscles, temporalis muscle, maxillary artery, branches of V3 and VII, otic ganglion o Muscles of mastication: innervated by branches of mandibular nerve (V3), supplied by branches of maxillary artery  Temporalis, masseter, lateral pterygoid, medial pterygoid  Gravity is the prime mover when opening the mouth o Temporomandibular joint (TMJ) dislocated in ANTERIOR direction typically o Branches of mandibular nerve: muscular branches, meningeal, buccal, auriculotemporal, inferior alveolar, lingual • Pterygopalatine fossa o Openings  Pterygomaxillary fissure (lateral wall)  Inferior orbital fissure  Sphenopalatine foramen  Foramen rotundum  Pterygoid canal  Palatine foramina o Contents  Pterygopalatine part of maxillary artery (branches!!)  Maxillary nerve Lecture 16: Oral and Nasal Cavities • Nasal cavity o From external nares to the choanae o Warm/humidify air (mouthbreathers do not have humidification of air!) o Close proximity of brain and nasal cavity o Blood supply from sphenopalatine artery (branch of maxillary artery) o Paranasal sinuses  Designed to make head lighter  Middle meatus: ethmoid air cells, maxillary and nasal sinuses  Superior meatus: posterior ethoid air cells, sphenoid sinus

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Inferior meatus: nasolacrimal duct

Oral cavity o Glands lubricate food (many  redundancy) Pharynx o Soft palate: sensory branches of V2 and glossopharyngeal nerves, soft palate muscles are innervated by the vagus nerve EXCEPT tensor veli palatine (innervated by V3) o Hard palate innervated by V2- greater and lesser palatine foramina o Teeth  Upper teeth innervated by maxillary nerve  Lower teeth innervated by mandibular nerve o Tongue Anterior 2/3 Posterior 1/3 Taste VII-chorda tympani IX Touch V3- lingual IX Motor XII XII • Extrinsic muscles of the tongue: genioglossus, hyoglossus, styloglossus (all innervated by hypoglossal nerve) and palatoglossus (innervated by vagus nerve) • Intrinsic muscles of the tongue: all innervated by hypoglossal nerve Larynx

Lecture 17: Cervical Region • Strap muscles of the neck o Omohyoid, sternohyoid, sternothyroid, thyrohyoid o Innervated by ansa cervicalis which loops around internal jugular vein o Stabilizes the hyoid and thyroid cartilages for swallowing, speech • Cervical plexus: motor o Ansa cervicalis, phrenic nerve (breathing), accessory nerve • Triangles of the neck o Posterior triangle  Borders: trapezius, clavicle, sternocleidomastoid  Contents: brachial plexus, vascular, CN XI o Anterior triangle  Carotid • Borders: omohyoid, digastric muscle, sternocleidomastoid • Contents: LOTS of vasculature (Internal jugular vein, common carotid artery), vagus nerve  Muscular • Borders: midline, omohyoid, sternocleidomastoid • Important structures: strap muscles • Anterior scalene between subclavian vein and subclavian artery • Blood supply o Arterial: high pressure blood flow IN (not symmetric)  Common carotid, internal carotid, external carotid arteries o Venous Lecture 18: Visceral Structures of Neck • Branchial arches • Branchial cyst- 2nd arch grows over and attaches but does not disappear  lump on lateral side of neck • Branchial fistula- membrane between 2nd and 3rd arch breaks down leading to communication between pharynx and skin • Visceral sinus- 2nd arch grows over and does not attach

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Carotid sheath contents: vagus nerve, common carotid artery, internal jugular vein Deep cervical fascia: investing layer, pre-trachial layer, pre-vertebral layer

Lecture 19: Pharynx and Larynx • Pharynx o Nasopharynx  Auditory (Eustachian) tubes open into lateral wall  Pharyngeal isthmus closed off during swallowing  Adenoids (nasopharyngeal tonsils)= lymphatic tissue o Oropharynx  Palatine tonsils between palatoglossal and palatopharyngeal arches  Tonsillitis: infectious disease affecting tonsils or adenoids • Lymphatics drain into jugulodigastric lymph nodes o Laryngopharynx  Piriform fossae (swallowed objects may lodge in this fossae… During extraction, be careful not to damage internal branch of superior laryngeal nerve- branch of vagus nerve) o Pharyngeal muscles (6 paired muscles)  Superior pharyngeal constrictor  Middle pharyngeal constrictor  Inferior pharyngeal constrictor • Attaches to cridoid and thyroid cartilages • Innervated by external pharyngeal nerve and recurrent laryngeal nerve  Stylopharyngeus (innervated by CN IX)  Salpingopharyngeus  Palatopharyngeus o Innervation of the pharynx o Pharyngitis: inflammation of pharynx, usually viral o Swallowing (dysphagia= problem swallowing) • Larynx (voice production) o Skeleton  Thyroid cartilage  Cricoid cartilage (forms a complete ring)  Arytenoid (2)  Corniculate  Cuneiform o Membranes/ligaments/folds  Rima glottides= space between the vocal folds o Muscles (innervated by recurrent laryngeal nerve)  Cricothyroids: innervated by external laryngeal nerve  Transverse arytenoids  Oblique arytenoids  Posterior cricoarytenoids: OPEN THE RIMA GLOTTIDIS  Thyroarytenoids  Lateral Cricoarytenoids  Vocalis o Innervation of the Larynx  Superior laryngeal nerve: Internal and external laryngeal nerves  Recurrent laryngeal nerve o Epiglottitis/supraglottitis: inflammation of the soft tissues above the vocal folds (life-threatening because this can obstruct airways) o Laryngitis o Croup: infection of upper respiratory tract