26 Anatomy Scalp Face Parotid PDF

Scalp, Face & Parotid Class Year 2, Semester 1 Lecturer Fiona Cronin Department of Anatomy [email protected] Date 14-11-2024 1  Learning Outcomes List the layers of the scalp, its blood supply, and bleeding from t...

Scalp, Face & Parotid Class Year 2, Semester 1 Lecturer Fiona Cronin Department of Anatomy [email protected] Date 14-11-2024 1  Learning Outcomes List the layers of the scalp, its blood supply, and bleeding from the scalp Describe the superficial temporal artery and the facial artery Describe the veins of the face and temporal region Identify the major muscles of the face and jaw Describe the seventh cranial nerve: its relations, lesions and testing Describe the parotid gland and its duct, their relations and clinical conditions and its secretomotor innervation Describe the anatomy of the ophthalmic division of the trigeminal nerve, including how their integrity is tested clinically. The Scalp Layers of the scalp  SCALP Skin Thin except in occipital region Abundance of sweat, sebaceous glands & hair follicles Abundant arterial supply, good venous & lymphatic drainage Connective tissue layer / sub-Cutaneous tissue Consists numerous blood vessels & nerves Wounds bleed profusely as blood vessels are prevented from retraction by fibrous tissue Aponeurosis Tendinous sheet of occipitofrontalis Loose connective tissue dangerous layer of scalp Periosteum Cephalhaematoma  Skin Connective Aponeurosis Loose Periosteum tissue connective tissue The blood in the layer of loose connective tissue is drained by veins, some of which enter the skull bones and cranial cavity as EMISSARY VEINS. The blood flow in these veins is from superficial to deep, and they can carry infection into the intracranial cavity with serious consequences. Ceph Clinical application  Clinical application Subaponeurotic Haemorrhage Sub-periosteal haematoma (Cephalhaematoma) Black eye (Periorbital hematoma) secondary to trauma to scalp A bleeding scalp wound (External) ARTERIAL SUPPLY TO SCALP ARTERIAL SUPPLY TO SCALP  VENOUS DRAINAGE  VENOUS DRAINAGE Veins of the scalp freely anastomose with one another and are connected to the diploic veins of skull bones Drain into the internal and external jugular veins They are connected to intracranial venous sinuses by emissary veins. Why is this important? LYMPHATIC DRAINAGE OF SCALP The anterior scalp drains to the parotid glands, and the posterior scalp drains to the retroauricular lymph nodes. 14  Anterior to ears/vertex Supratrochlear and Supraorbital (V1) Zygomaticotemporal (V2) Nerve Supply to the Scalp Auriculotemporal (V3) Posterior to ears/vertex Great auricular (C2/3) Lesser occipital (C2) Branches of which cranial nerve? Greater occipital(C2) Third occipital (C3) The Face  FACE Anterior aspect of head from forehead to chin and from one ear to the other Skin of the face is: Elastic Vascular (bleed profusely however heal rapidly) Consists numerous sweat and sebaceous glands Connected to underlying bones by loose connective tissue, which contain muscles of facial expression Superficial fascia – contains facial muscles, blood vessels & nerves, fat tissues (absent in the eye lids) No deep fascia in the face except over?  MUSCLES OF THE FACE Called muscle of facial expression and lie in the superficial fascia Take origin from the facial bones & are inserted into the skin Embryologically, they develop from mesoderm of 2 nd pharyngeal arch, therefore supplied by facial nerve Facial muscles serve as sphincters or dilators of orifices of face, namely the orbit, nose and mouth 19 MUSCLES AROUND ORBIT ❑ Orbicularis oculi ❑ Levator palpebrae superioris ❑ Corrugator supercilii 20  MUSCLES AROUND NOSE ❑ Compressor naris ❑ Dilator naris ❑ Procerus ❑ Levator labii superioris alaeque nasi 21  MUSCLES AROUND MOUTH ❑ Orbicularis oris ❑ Levator labii superioris ❑ Zygomaticus minor and major ❑ Levator anguli oris (deep to zygomatic muscles) ❑ Risorius ❑ Depressor anguli oris ❑ Depressor labii inferioris ❑ Mentalis Muscle of cheek ❑ Buccinator 22 (surprise) (anger, frowning) (squinting) 23 PLATYSMA: This muscle lies in the SUPERFICIAL FASCIA, just deep to the skin. It is the largest of the MUSCLES OF FACIAL EXPRESSION, which Platysma are supplied with motor muscle innervation by the FACIAL NERVE (Cranial Nerve VII). Contraction of the platysma Model tightens the skin of the neck MT900 and, pulls the corners of the mouth down, and lifts the skin over the upper thorax. The facial expression it conveys is one of mixed shock, disbelief and horror. (The name is derived from the Greek, platusma, a flat object)  FACIAL MUSCLES Muscles Branches of Facial nerve Actions (CN VII) Frontalis Temporal branch Raise eyebrows Orbicularis oculi Zygomatic branch Closing the eyelids Buccinator Buccal branch Pushes food from the vestibule of the mouth into the oral cavity proper Orbicularis oris Marginal Mandibular Closing the lips Platysma Cervical branch Helps with shaving !  BRANCHES OF FACIAL NERVE SUPPLYING THE FACIAL MUSCLES LYMPHATIC DRAINAGE  JAW MUSCLES The Muscles of Mastication These are the muscles that move the lower jaw or mandible. The upper jaw or maxilla is fixed to the base of the skull. There are four principal muscles, all innervated by motor fibres from the TRIGEMINAL NERVE: MASSETER TEMPORALIS MEDIAL PTERYGOID LATERAL PTERYGOID Some authorities add a fifth, the DIGASTRIC. Parotid gland PAROTID GLAND Largest of salivary gland, composed mostly of serous acini, enclosed by thick Main trunk of facial nerve emerging from stylomastoid foramen parotid fascia derived from investing layer of deep cervical fascia Secretes 25% of saliva Serous (watery secretions) 30 The PAROTID SALIVARY GLAND is covered by a thin capsule of fibrous tissue. Opening the mouth presses the ramus against the gland. If the gland is swollen and tender, as it is in the infectious disease MUMPS, attempting to open the mouth is quite painful. Duct of Parotid Salivary Gland, passing through buccinator in front of masseter Accessory Parotid Gland Masseter Parotid muscle Salivary Gland Submandibular Salivary Gland Model MC900  STRUCTURES WITHIN THE PAROTID GLAND The EXTERNAL CAROTID ARTERY lies deep within the gland, where it divides into its two terminal branches, the MAXILLARY and SUPERFICIAL TEMPORAL arteries. Superficial to the artery lies the RETROMANDIBULAR VEIN which is formed by the union of the MAXILLARY and SUPERFICIAL TEMPORAL veins. It divides into ANTERIOR and POSTERIOR DIVISIONS within the gland. Superficial to the vein lies the FACIAL NERVE which runs forwards, dividing into its five terminal branches: TEMPORAL, ZYGOMATIC, BUCCAL, MANDIBULAR and CERVICAL. A few PAROTID LYMPH NODES, usually classified as SUPERFICIAL and DEEP, also lie within the gland. STRUCTURES WITHIN THE PAROTID GLAND 33  PAROTID DUCT (STENSEN DUCT) Thick-walled duct, about 5 cm long, emerges from middle of anterior border of the gland Runs forward on masseter with transverse facial artery & upper buccal above and lower buccal branch of facial nerve below Opens into vestibule of mouth opposite the crown of upper 2nd molar tooth 34  PARASYMPATHETIC INNERVATION TO THE GLAND  Clinical application Parotid gland tumour Parotitis – inflammation Inflammatory Infective i.e. stone in duct, bacterial Viral - Mumps caused by the mumps virus  FREY’S SYNDROME This is a rare condition which can occur following trauma (most commonly, surgery) to the auriculotemporal nerve in the parotid area. The patient complains of redness and sweating in the cheek and temporal area on the affected side, whenever they are eating or even thinking of food. 38 External carotid artery  Branches of the External Carotid Artery from the anterior surface: SUPERIOR THYROID Model PO81/6 shows LINGUAL most of these vessels. FACIAL It is available for study in the Anatomy Lab from the posterior surface: OCCIPITAL POSTERIOR AURICULAR from the deep surface: ASCENDING PHARYNGEAL at the level of the neck of the mandible: TERMINAL BRANCHES MAXILLARY SUPERFICIAL TEMPORAL  TRANSVERSE LATERAL FACIAL The Facial Artery NASAL ARTERY ARTERY It arises just below the angle of the mandible, it loops upwards, deep to the mandible, giving off the TONSILLAR ARTERY which supplies the palatine tonsil. It then turns downwards, giving off the SUBMENTAL ARTERY which runs forwards supplying the muscles in the floor of the mouth, the overlying skin, the chin and lower lip. It crosses the lower border of the mandible where it can be readily palpated. It then follows a very sinuous course towards the inner angle of the eye, giving off the INFERIOR LABIAL ARTERY which supplies SUPERFICIAL the lower lip, the SUPERIOR LABIAL TEMPORAL ARTERY which supplies the upper lip and SUPERIOR ARTERY LABIAL nasal septum, and the LATERAL NASAL ARTERY SUBMENTAL ARTERY ARTERY which supplies the nose. (Latin, sub- = under, and mentum = the chin) FACIAL NERVE  Introduction 7th cranial nerve Mixed nerve – consists both sensory (nervous intermedius) & motor roots Has parasympathetic function which passes through the sensory root Attached to the lower border of the pons between the olive and inferior cerebellar peduncle Course of the Facial nerve Divided by the stylomastoid foramen into intracranial and extracranial part  INTERNAL INTERNAL ACOUSTIC ACOUSTIC MEATUS FORAMEN JUGULAR MEATUS FORAMEN JUGULAR OVALE OVALE FORAMEN FORAMEN FORAMEN FORAMEN MAGNUM MAGNUM PITUITARY PITUITARY FOSSA FOSSA MASTOID PROCESS Model MB26 STYLOMASTOID STYLOID FORAMEN PROCESS  Branches of Facial nerve Greater petrosal nerve In the facial canal Nerve to Stapedius – supplies the Stapedius muscle Chorda tympani nerve - arises from the nerve about 6mm above the stylomastoid foramen. Conveys the taste fibers from the anterior 2/3 rd of the tongue and preganglionic secretomotor fibers for submandibular & sublingual glands Below the stylomastoid foramen Posterior auricular nerve - supplies muscles around the auricle and occipital belly of Occipito-frontalis Nerve to the posterior belly of digastric Nerve to the stylohyoid muscle In the face: Temporal Zygomatic Buccal Marginal mandibular Cervical  Clinical application Facial nerve paralysis: lesion at different levels Supranuclear Nuclear Infra-nuclear: Bell’s palsy Lesion in the internal acoustic meatus Lesion at the genu (geniculate ganglion) Lesion distal to the genu Lesion below the stylomastoid foramen Bell’s palsy  Testing the Motor Function of the Facial Nerve While examining the facial nerve, look at the patient’s face carefully for signs of paralysis or asymmetry: loss of wrinkling of the forehead, drooping of the corner of the mouth and reduction in the labionasal fold. Tell the patient to… 1. Look upwards, raise the eyebrows and wrinkle the forehead. You should assess the muscle strength by gently pushing the forehead down on each side. (Temporal branches) 2. Close the eyes tightly. You should gently try to open them with your fingers, and if all is well you will not succeed. (Zygomatic branches) 3. Puff out (i.e. inflate) the cheeks as if about to whistle. The face should be symmetrical and no air should escape from the mouth. (Buccal branch) 4. Grin and show the teeth. The face should be symmetrical with the same amounts of teeth showing on each side. (Buccal and Mandibular branches) 5. Contract the platysma. There is no simple way of asking the patient to do this so just tell the patient to imitate what you are doing, and perform the action. If you know of a better way, please tell me! (Cervical branch)  References Snell’s Clinical Anatomy by Regions Clinically oriented Anatomy by Keith L. Moore Acknowledgement Practice questions Google images http://teachmeanatomy.info/ Prof Robin O’ Sullivan