Face & Scalp Anatomy PDF

Anatomy of the head and neck – The face Anatomy of the Head & Neck The face [email protected] ANATOMY 0 Lecture outcomes Ø Define the face as a discrete region Ø Describe the main visible features of the face (surface anatomy) Ø Define the musculature of the face: origin, insertion and func...

Anatomy of the head and neck – The face Anatomy of the Head & Neck The face [email protected] ANATOMY 0 Lecture outcomes Ø Define the face as a discrete region Ø Describe the main visible features of the face (surface anatomy) Ø Define the musculature of the face: origin, insertion and function Ø Define the veins, arteries and nerves* of the face * the trigeminal nerve – origins and distribution * cutaneous innervation of the face, particularly the branches of the facial nerve Ø Provide a short account of the anatomy of the salivary glands ANATOMY 1 The face as a discrete region Ø The face covers the anterior surface of the head, limited: - superiorly by the forehead - inferiorly by the chin - laterally by the ears Arrows and dashed line highlight facial borders © Visible Body ANATOMY 2 Facial subregions Facial Subregions Ø But for the purpose of diagnosis* (clinical scenario) the face is subdivided into subregions *for instance, to describe the location of injuries, pathologies or for surgery Ø These are shown below: © Clinically Oriented Anatomy. 7th Ed. Moore et al ANATOMY 3 The face – contents and role The face – contents and role Ø Contents of the face are mainly : - facial bones - musculature - includes salivary glands - the housing for special senses such as the eyes, nose and mouth Ø Its role is to: - provide human identity - mediate what is termed as interface, i.e. expression/communication ANATOMY 4 The facial skeleton The facial skeleton Ø The facial bones comprises the subgroup that relates to the viscerocranium only, the remaining encloses the brain and therefore called the neurocranium Ø ANATOMY The (14) facial bones are: inferior turbinal (2) lacrimal (2) maxilla* (2) mandible* nasal* (2) palatine (2) vomer zygomatic* (2) Ø The bones indicated with a *, along with the frontal bone, generally dictate most of the shape of the face Ø ‘Most’ because other tissues, such as fat on cheeks etc, are also responsible for our facial feature 5 The facial skeleton 2 The facial skeleton inferior turbinal lacrimal mandible* maxilla nasal palatine vomer zygomatic ANATOMY © BodyParts3D Ø The mandible is the only facial bone that articulates, with the temporal bone, via the TMJ 6 Muscles of the face Muscles of the face Ø These are very superficial, since there is little tissue or fat between the skin and the skull bones, except in the cheek area Ø These can be easily shown on a prosection that had its skin removed Ø It is also easy to isolate and view the motor nerves and blood vessels to the muscles of the face Ø The facial muscles originate on bone but insert onto skin, unlike the majority of skeletal muscles, in order to perform its role of facial expression instead of moving joints, limbs etc ANATOMY 7 Muscles of the face 2 Ø - ANATOMY Muscles of the face Can be classed into three subgroups: Muscles of scalp, forehead and eyebrows Muscles of mouth, lips and cheeks Muscles of orbital opening 8 Muscles of the face Muscles of the face 3 Ø Together there are some 17 different facial muscles, the table below summarises the most commonly and important muscles to learn Name Origin and Insertion Actions Epicranius: Frontalis & Occipitalis Cranial aponeurosis to eyebrows Raises the eyebrows Orbicularis oculi Portions of the frontal and maxilla to the skin around eyes Blinks and closes eyes Orbicularis oris Skin around mouth Closes and protrudes lips Buccinator Mandible/maxilla to skin around mouth Flattens cheek against teeth Zygomaticus Zygomatic bone to corner of lips Raises corner of mouth Platysma Fascia of chest to lower border of mandible Draws mouth downward ANATOMY 9 Muscles of the face – Orbicularis oculi and epicranius Muscles of the face – Orbicularis oculi and epicranius Ø Orbicularis oculi is more a muscle of the eye, albeit also one of the superficial muscles of facial expression. This muscle originates from the frontal bone, maxilla as well as lacrimal bones and inserts onto the skin around the margin of the orbit. Used to blink the eye Ø The epicranius (occipitalis + frontalis, highlighted in blue) is a muscle of the scalp, originating from either the occipital bone or epicranial aponeurosis and inserting onto the eyebrows. It acts to raise the eyebrows ANATOMY Orbicularis oculi © Visible Body 10 Muscles of the face – Orbicularis oris ‘OO’ Muscles of the face – Orbicularis oris ‘OO’ Ø Also commonly known as the oral sphincter Ø Composed of multiple layers, some of which are extrinsic – originating from other muscles such as the buccinator or zygomatic Ø This muscle decussates (i.e. intersects) at the corner of the mouth Note that there is no specific bony origin for this muscle. The red cubes indicate the separate origins to the OO muscle from others, such as buccinator ANATOMY © Visible Body 11 Muscles of the face - Buccinator Muscles of the face Buccinator Ø Also commonly known as the ‘cheek’ muscle, originating from both the mandible and maxilla (white arrows) and inserting onto the orbicularis muscle at the angle of the mouth Ø Presses cheek against the teeth, so pushes food onto molars, also for suckling insertion origin ANATOMY origin © Visible Body 12 Muscles of the face - Zygomaticus Muscles of the face Zygomaticus Ø This long, cord-like muscle projects from the zygomatic bone to insert onto both the orbicularis and levator anguli oris muscles Ø Contracting this muscle raises the angle of the mouth – Smiling, or grinning ANATOMY © Visible Body 13 Muscles of the face - Platysma Muscles of the face Platysma Ø This broad, thin muscle extends from the clavicle and into the mandible Ø Its role is to tense the skin but also acts to depress the mandible, as shown in the image on the right ANATOMY © Visible Body 14 Blood supply to the face Blood supply to the face Ø Blood supply to the head and face will be covered in detail at a later lecture Ø However, at this stage it can be said that the principle supplier of blood to the face is the external carotid artery, highlighted in blue in the figure below Ø The external carotid gives off numerous branches, however the most relevant to the facial region are: - Facial branch, supplying the skin and muscles of the face - Transverse facial - Lateral nasal - Labial (sup and inf) Maxillary artery Facial artery ANATOMY © Visible Body 15 Venous drainage of the face Venous drainage of the face Ø Most of the veins of the face follow a parallel path to the equivalent-named arteries, e.g. facial veins Ø Blood is drained from a plexus of vessels at the surface that drain the anterior scalp, forehead, eyelids, nose etc, first into the facial vein as it travels from the side of the root of the nose to the angle of the mandible Ø The facial vein ultimately drains into the internal jugular vein Ø Deeper tissues of the face are drained by other vessels, e.g.: ANATOMY - the deep facial vein which joins the facial vein described above - the retromandibular, which divides to either drain into the facial vein or a second branch that forms the external jugular Facial vein Internal jugular vein 16 Innervation of the Innervation of the face and facial muscles face and facial muscles Ø Innervation of these structures is via two main routes: - The trigeminal nerve encodes mostly cutaneous , i.e. sensory, innervation of the face (and scalp), although has a minor motor contribution - The facial nerve (CN VII) provides motor innervation to the facial muscles ANATOMY 17 The trigeminal nerve The trigeminal nerve Ø Originates from the pons, at the base of the brain Ø This nerve is the coming together of two roots: sensory and motor Ø As its name suggest the trigeminal nerve has three divisions: 1. Ophthalmic (sensory) 2. Maxillary (sensory) 3. Mandibular (mixed) Ø The minor motor contribution is from fibres that target primarily the muscles of mastication ANATOMY 18 The trigeminal ganglion, the motor root and ophthalmic div The trigeminal ganglion, the motor root and ophthalmic div Ø The sensory divisions comprise of pseudounipolar neurones located within a sensory ganglion, aptly named trigeminal ganglion Ø This contrasts to the motor root, which has the neurone cell bodies within the pons Ø The ophthalmic division will cross the sup orbital fissure to supply several structures around the eye and nose Peripheral tissue Pons Pseudounipolar neurone (source: Wikipedia) ANATOMY Trigeminal ganglion 19 The maxillary division The maxillary division Ø Also exclusively sensory, this nerve crosses foramen rotundum to target several structures within the maxilla, such as the mucosa of the maxillary sinus or the posterior teeth, as well as the skin ANATOMY 20 The mandibular division The mandibular division Ø This nerve exits the skull via the foramen ovale Ø Main branches are: - auriculotemporal, supplying the skin in front of the ear - lingual, sensory to the anterior 2/3rds of the tongue - buccal, supplying the skin and lat walls/floor of oral mucosa - inferior alveolar, entering the mandibular bone through the mandibular foramen, gives rise to the inferior dental plexus and exits onto the face as the mental nerve ANATOMY 21 Cutaneous targets by the three divisions of the trigeminal nerve ANATOMY Cutaneous targets by the three divisions of the trigeminal nerve 22 Cutaneous innervation of the face Cutaneous innervation of the face Ø Ophthalmic cutaneous nerves: - supraorbital - supratrochlear Ø Maxillary cutaneous nerves: - Infraorbital - Zygomaticofacial - zygomaticotemporal Ø Mandibular cutaneous nerves: - mental - auriculotemporal ANATOMY © Clinically Oriented Anatomy. 7th Ed. Moore23et al Trigeminal neuralgia Trigeminal neuralgia Ø Trigeminal neuralgia is a rare episodic facial pain that is unilateral, electric shock like and provoked by light touch Ø It affect more females than males and the incidence increases with increasing age Ø In 95% of cases vascular compression of the nerve root is the source of the problem Ø In the 10% of cases where the drug treatment* is ineffective surgery is suggested but it is not without risk, e.g. hearing loss Microvascular decompression * Antiepileptic drugs (e.g. carbamazepine) are more effective than pain medication ANATOMY Basilar artery Pre operation Post Operation Wang et al 2019 24 The facial nerve The facial nerve Ø The facial nerve is composed of a primary motor root, the facial nerve proper, but has also a sensory/parasympathetic component Ø It also has a special sensory role, specifically that of taste Primary motor Visceral motor Special sensory General sensory ANATOMY 25 The facial nerve The facial nerve Ø The primary motor is the largest component. It supplies primarily the muscles of facial expression but also posterior belly of digastric muscle, stylohyoid and stapedius Ø The Visceral motor is comprised of presynaptic parasympathetic fibres to the pterygopalatine ganglion, which innervates the lacrimal glands as well as the submandibular and sublingual salivary glands Ø However, the pterygopalatine ganglion is also associated with innervation of the mucous membrane of the nasopharynx as well as that of the hard and soft palate (via the maxillary or mandibular branches of the trigeminal) ANATOMY 26 The facial nerve 2 The facial nerve Ø The special sensory role – taste – from the anterior 2/3 of the tongue is carried by fibres of the chorda tympani, which join the lingual nerve (from CN V3) Ø Finally, some fibres take the role of general somatic sensation of the skin of the concha of the auricle (ear) Primary motor Visceral motor Special sensory General sensory ANATOMY 27 Motor control of muscles of the face Motor control of muscles of the face Image on the right illustrates the path taken by motor fibres from the motor cortex to the target muscles, including the foramina allowing the passage of these fibres ANATOMY 28 The parotid gland The parotid gland Ø Tightly enclosed in fascia, thus swelling of this gland can become painful “mumps” Ø The facial nerve, as it travels towards the face, actually creates a plexus that passes within the parotid gland, although – curiously – it does not innervate this gland Ø Saliva production arises from activity of the parasympathetic fibres within the glossopharyngeal nerve (CN IX) Ø Parotid duct lies on masseter and pierces buccinator - opens into oral cavity on buccal side of upper left second molar Ø External carotid divides into its terminal branches in the gland (maxillary artery and superficial temporal) ANATOMY 29 To recap: Lecture outcomes To recap: Lecture outcomes Ø To be able to define the borders that define the facial region Ø List the main anatomical structures that comprise the face, including those that define its shape, namely facial bones Ø Define the musculature of the face: origin, insertion and function Ø Define the veins, arteries and nerves* of the face * the trigeminal nerve – origins and distribution * cutaneous innervation of the face, particularly the branches of the facial nerve Ø Provide a short account of the anatomy of the salivary glands ANATOMY 30 Questions? Questions? Email: [email protected] ANATOMY 31