Lecture 4 - THE SCALP AND FACE.pdf

THE SC ALP - INTRODUCTION • The scalp consists of five (5) layers of tissue that cover the osseous cranium. • It extends from the superior nuchal line on the posterior aspect of the skull to the supraorbital margins anteriorly. • Laterally, it extends to the level of the zygomatic arches. THE SC...

THE SC ALP - INTRODUCTION • The scalp consists of five (5) layers of tissue that cover the osseous cranium. • It extends from the superior nuchal line on the posterior aspect of the skull to the supraorbital margins anteriorly. • Laterally, it extends to the level of the zygomatic arches. THE SC ALP - LAYERS 1. 2. 3. 4. 5. Skin Subcutaneous tissue with large superficial vessels and nerves. Aponeurosis and the occipitofrontalis muscle – epicranial aponeurosis (galea aponeurotica). Loose areolar CT – subaponeurotic tissue - with emissary veins. This layer is clinically important because superficial infection of the scalp may spread to deeper layers through the emissary veins which communicate with the intracranial (subdural) venous sinuses. Pericranium - periosteum. THE SC ALP - LAYERS •The first three (3) layers of the scalp: skin, subcutaneous tissue, and epicranial aponeurosis, are referred to as the scalp proper. •They are clinically and surgically regarded as one single layer. NERVES OF THE HEAD AND FACE NERVES OF THE HEAD & NECK • TRIGEMINAL NERVE (CN V): • Ophthalmic nerve (V1) superior orbital fissure • Supraorbial n • Supratrochlear n • External nasal n • Infratrochlear n • Lacrimal n • Maxillary nerve (V2) - foramen rotandum • Zygomaticofacial n • Zygomaticotemporal n • Infraorbital n • Mandibular nerve (V3) - foramen ovale • Buccal n • Auriculotemporal n • Mental n • LESSER OCCIPITAL NERVE (C2,3) – cervical plexus • GREATER OCCIPITAL NERVE (C2) • THIRD OCCIPITAL NERVE (C3) NERVES OF THE FACE AND SCALP ARTERIES OF THE SC ALP • ECA: • Occipital artery • Posterior auricular artery • Superficial temporal artery (terminal branch. It accompanies the auriculotemporal n. [V3]) • ICA: • Supratrochlear artery (ophthalmic a.) • Supraorbital artery (ophthalmic a.) ARTERIES OF THE FACE AND SCALP THE FACE - INTRODUCTION •It is the part of the head that is visible in the frontal or anterior view. •It corresponds to all that is anterior to the external ears, and between the hairline and the chin. NERVES OF THE FACE NERVES OF THE FACE • The cutaneous, sensory, supply of the face is largely through the trigeminal nerve (CN V) and its three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3). • Also, the great auricular nerve from the cervical plexus (C2) contibutes by supplying the skin over the angle of the mandible and the anterior and posterior auricle. • The motor innervation is supplied by the facial nerve (CN VII) and its branches. FACIAL NERVE • The facial nerve (CN VII) supplies motor innervation to the superficial muscles of the neck (platysma), muscles of facial expression, and the muscles of the scalp. • The sensory component of the facial nerve supplies taste (special sensory) to the anterior 2/3 of the tongue, and it also conveys general sensation from the external acoustic meatus. • The autonomic component - secretory motor (visceral motor) – parasympathetic to the submandibular, sublingual and intralingual salivary glands, lacrimal gland. Submandibular ganglion Pterygopalatine ganglion FACIAL NERVE • The facial nerve emerges from the skull through the stylomastoid foramen, between the mastoid and styloid processes of the temporal bone. • It enters the parotid gland in the parotid region of the face, and it divides into five (5) terminal branches. FACIAL NERVE - BRANCHES 1. Temporal Branch = frontalis and orbicularis oculi muscles 2. Zygomatic Branch = orbicularis oculi muscle 3. Buccal Branch = muscles of the upper lip and nostrils 4. Mandibular Branch = muscles of the lower lip 5. Cervical Branch = platysma muscle • Other Branches: • Posterior Auricular nerve = occipitalis muscle and auricles • Nerve to the Stapedius muscle = middle ear • Nerve to the posterior belly of the Digastric and Stylohyoid muscles UMN LMN EXAMINATION OF THE FACIAL NERVE • Facial muscles: whistle, drink with a straw, show teeth, blow. • Lacrimation: irritating nasal mucosa with e.g., ammonia. • Sensitivity to sound: audiometer (hyperacusis). • Taste to anterior 2/3 of tongue: sweet, sour, bitter (chorda tympani). FACIAL NERVE DAMAGE • Ipsilateral muscle paralysis (Bell’s Palsy). • Loss of taste to the anterior 2/3 of the tongue. • Hyperacusis. • Decreased lacrimation. NOTE: Presentation is dependent on where the injury occurs: i.e., facial canal vs. geniculate ganglion vs. stylomastoid foramen vs. cerebello-pontine angle. FACIAL NERVE DAMAGE • When the patient is asked to smile, the facial musculature pulls to the opposite side of the injury. • When the patient attempts to close his/her eye, the eyeball rolls upwards and outwards – Bell’s phenomenon ARTERIES OF THE FACE •Facial artery (ECA) •Superficial Temporal artery (ECA) •Transverse Facial Artery (Superficial Temporal artery [ECA]) ARTERIES OF THE FACE AND SCALP FACIAL ARTERY • The facial artery is a branch of the ECA. • It runs over the lower border of the mandible. • It anastomoses with the branches of the ophthalmic artery (ICA). This point is a connection between the internal and external carotid arteries. • BRANCHES: • Inferior Labial artery = lower lip • Superior Labial artery = upper lip. Gives septal and alar branches to the nose • Angular artery = terminal branch which anastomoses with the dorsal nasal and palpebral arteries of the ophthalmic artery (ICA) FACIAL VEIN • The facial vein begins near the medial angle of the eye (medial canthus) as the angular vein where it is formed by the union of the supratrochlear and supraorbital veins. • It descends posterior and superficial to the facial artery. • At the inferior margin of the mandible, it is joined by the anterior retromandibular vein. • It terminates into the internal jugular vein. • It communicates with the superior ophthalmic vein which drains into the cavernous sinus of the skull, which then drains into the internal jugular vein. MUSCLES OF THE FACE • The muscles of facial expression are all supplied by the facial nerve (CN VII). • They are very superficial in location attaching to the deep layers of the skin. • They vary in strength and shape. • They are grouped into: • Muscles of the scalp and auricle • Muscles around the orbit (eyelid) • Muscles of the nose • Muscles of the mouth • Platysma muscle MUSCLES OF THE FACE • MUSCLES OF THE SCALP: • Frontalis or occipitofrontalis = elevates the eyebrows (surprised look); wrinkles the forehead (frown) • Procerus = continuation of the frontalis muscle. Pulls down the eyebrows. • MUSCLES OF THE NOSE: • The nasalis muscle has two components • Transverse (compressor naris) • Alar (dilator naris) • MUSCLES OF THE ORBIT: • Orbicularis oculi • Orbital • Palpebral • Lacrimal • ACTION: Closes the eyelid; dilates the lacrimal glands. Paralysis of this muscle results in inability to close the eye, and drooping of the lower eyelid (ectropia) and “spilling” of the tears (epiphora) • Levator palpebrae superioris (CN III) – not related to this group. Muscle of the eyelid. MUSCLES OF THE FACE • MUSCLES OF THE MOUTH: • • • • • • • • • Orbicularis oris Levator labii superioris Zygomaticus minor/major Levator anguli Risorius Depressor anguli Depressor labii Mentalis Buccinator MUSCLES OF MASTIC ATION These muscles are all supplied by the trigeminal nerve (CN V3). MASSETER MUSCLE Elevates the mandible; also assists in protraction, retraction and side-to-side motion O- Zygomatic arch and maxilla I-Angle and lateral surface ramus TEMPORALIS MUSCLE O- Temporal line of the parietal bones and superior temporal surface of the sphenoid bone Elevates the mandible via its vertical fibers Retracts the mandible via its horizontal fibers. Lateral movement during chewing I-Coronoid process LATERAL PTERYGOID MUSCLE O-great wing of sphenoid, lateral surface of the lateral pterygoid plate I-condyle of the mandible MEDIAL PTERYGOID MUSCLE O-medial side of lateral pterygoid plate I-Angle of the mandible Protrudes the mandible, and lateral movements during chewing. A concerted effort (both muscles) of the lateral pterygoid muscles helps in lowering the mandible and opening the jaw, whereas unilateral action of a lateral pterygoid, produces contralateral protrusion used during chewing in combination with the action of the medial pterygoid. Raises the mandible (adducts) TEMPOROMANDIBULAR JOINT TEMPOROMANDIBULAR JOINT • It is a synovial joint located between the glenoid cavity of the temporal bone and the condyle of the mandible. • The articular surface consists of an oval-shaped fibrocartilage surrounded by a joint capsule. • The articular disc (cartilage) is divided into an upper and lower cavities. • NERVE SUPPLY: auriculotemporal nerve (V3), maseteric and deep temporal nerves. BREAKDOWN OF STRUCTURES BONE Condyle Glenoid (madibular) fossa Articular tubercle (eminence) JOINT COMPONENTS Articular disc Articular space LIGAMENTS Temporomandibular (lateral)-prevents posterior and lateral displacement Sphenomandibular-limits distention of the mandible in an inferior direction. Most commonly damaged in an inferior alveolar nerve block Stylomandibular-limits excess opening Capsular ligament (fibrous capsule) MOVEMENTS OF THE TMJ • Rotation (opening/closing the mouth) • Translation (protrusion/retrusion of the mandible) • Grinding movements during mastication. TMJ DISORDER • This is a condition caused by dysfunction of the temporomandibular joint. • It has an extensive etiology to include: • • • • • • • • Previous or chronic dislocation of the jaw Osteoarthritis Stress – clenching of the teeth Poor muscle tone Improperly aligned teeth Whiplash Missing teeth Muscle abuse habits: e.g., chewing gum TMJ DISORDER • S & S: • Periorbital headache • Difficulty chewing, moving the jaw(open/close) with associated pain • Tinnitus (“fullness”/“ringing”) in the associated ear • Clicking, popping of the jaw with possible dislocation or subluxation • Otitis without infection • Dizziness • Cervical pain • TREATMENT: • Drug therapy: analgesics, NSAID’s • Orthodontic splints • Habit changes: posture, diet • Stress reduction • Surgical (arthroscopic surgery) intervention to remove/reshape bone and cartilage