Muscles and regional anatomy of the head and neck and the back Lecturer Dr M Samsam University of Central Florida Orlando Sources Platzer atlas and textbook of human anatomy and K Moore anatomy Skull 2 parts Neurocranium Facial skeleton Neurocranium 8 bones Frontal X1 Parietal X2 Temporal X2 Occipital X1 Sphenoid X1 Ethmoid X1 Facial Skeleton 14 bones Maxilla X2 Nasal X2 Zygomatic X2 Lacrimal X2 Palatine X2 Inferior Nasal Conchae X2 Mandible X1 Vomer X1 Skull continued Fontanels in the skull are the unossified remnants of the membranes in newborns Major fontanels are anterior ossified within 18 36 months posterior mastoid and sphenoid which are ossified within 6 month or more Foraminae of the skull and their contents Muscles of the head These are mimetic muscle radiate into the skin of the face and the head and their contraction causes displacement of the skin 4 groups A Muscles of the Scalp B Muscles in the region of eyelid C Muscles in the Nasal region D Muscle of the Mouth region A Muscles of the Scalp Epicranius Muscle Occipitofrontalis Has 2 bellies Frontal Occipital and in between the Galea Aponeurotica Temporoparietalis M Epicranius Function produces wrinkles in forehead and gives facial expression of Astonishment Innervation All mimetic muscles by Facial nerve cranial nerve CNVII Muscles in the region of eyelid or palpebral fissure Orbicularis Oculi muscle Has 3 parts Orbital Palpebral and Lacrimal Function produces folds in lateral angle of the eye expression of Worry and concern Corrugator supercilli Pulls the skin and eyebrow down and medially Produces vertical folds Protects against light Pathetic pain muscle Thinker s brow expression Innervation All mimetic muscles by Facial CNVII N Mimetic muscles in the region of the mouth Orbicularis Oris M Function its contraction closes the mouth Strong contraction gives a sucking shape Expression of reserve Buccinator M Quadrilateral in shape Origin mandible at 1st or 2nd molar region Forms the pterygomandibular raphe Extends to angle of the mouth and forms the lateral wall of its vestibule Function enables air to be blown out of the mouth Pulls angle of the mouth laterally Keeps the mucous membrane of the cheek free of folds Contraction gives expression of satisfaction Mimetic muscles in the region of the mouth Zygomaticus Major Origin zygomatic bone Insertion angle of mouth Function lifts the corner of the mouth upward giving expression of laughter or pleasure Zygomaticus Minor Origin zygomatic bone Insertion nasolabial groove Risorius laughing muscle Function together with zygomatic major it produces the nasolabial folds Its contraction gives expression of Action Levator labii superioris Origin Infraorbital margin to skin of upper lip Mimetic muscles in the region of the mouth Lavator anguli oris It lifts the angle of the mouth Giving expression of self confidence Depressor anguli oris Function pulls the angle of the mouth downwards and produces expression of sadness Depressor labii inferioris It pulls the lower lid down giving expression of perseverance Mentalis Produces chin lip furrow giving expression of doubt and indecision Platysma All mimetic muscles are innervated by facial N CNVII Muscles of Mastication Masseter temporalis Lateral and medial pterygoid All Innervated by Mandibular nerve CNV 3 Develop from 1st branchial arch CNV cranial nerve 5 trigeminal nerve It has 3 branches ophthalmic maxillary and mandibular Masseter M Origin Zygomatic arch Insertion masseteric tuberosity of mandible Has 2 parts Superficial part oblique fibers Deep part vertical fibers Function powerfully closes the jaw by elevating the mandible NN Masseteric N CNV 3 Temporalis M Origin temporal fossa as far as inf temp line Insertion by a strong tendon to coronoid process of mandible and mandibular ramus Function strongest elevator of lower jaw NN deep temporal N CNV 3 Muscles of Mastication Masseter temporalis Lateral and medial pterygoid Lateral pterygoid M Has 2 parts Function mandibular movements guiding muscle NN lateral pterygoid N CNV 3 Medial Pterygoid M Runs at right angles to the lateral pterygoid M Has 2 parts Angle of mandible is between this muscle and the masseter M Function elevates mandible and pushes it forward Rotational movement NN Medial pterygoid N CNV 3 Anterior Facial Regions First of all the blood supply of the face is mostly by ext carotid and partly by int carotid Facial artery from ext carotid passes it anastomose with dorsal nasal A coming from Ophthalmic A Forehead is supplied by supratrochlear A and supraorbital A both from ophthalmic A Facial vein anastomoses via Angular vein With dorsal nasal vein This anastomoses is extremely important since this allows a direct connection to Cavernous sinus through which infections eg from a furuncle on the lip may get into skull All mimetic muscles are innervated by branches of facial N temporal branch zygomatic buccal branch and marginal mandibular Anterior Facial Regions Sensory innervation to the face Is derived from branches of Trigeminal V nerve Ophthalmic V 1 Maxillary V 2 and mandibular V 3 nerves Ophthalmic nerve supplies the forehead Supratrochlear N and supraorbital Maxillary nerve supplies lower eyelid Cheek lateral nasal upper lip and anterior Temporal regions by Infraorbital N Mandibular N lower lip over mandible not angle and chin by mental N Auriculotemporal N supplies skin on Mandible ramus concha of auricle and Most part of ext layer of tympanic memb Sensitivity of the 3 branches of trigeminal N can be tested by pressing nerves This is a vertical line 2 3 cm lateral to midline Trigeminal Neuralgia Trigeminal neuralgia Tic Douloureux A disorder of unknown etiology cause associated with intractable pain along the 3 branches of trigeminal nerve but especially along maxillary and mandibular nerves A simple trigger such as touch cold or hot can start the pain Therapy Carbamazepine radiofrequency destruction of the branches involved Alcohol or Glycerin injection around the trigeminal ganglion Transection of the sensory root Vascular decompression of the trigeminal ganglion Hyoid bone Is in the neck but may be included with the bony skeleton of the skull PARTS Body anterior Greater horns laterally Lesser horns upwards Stylohyoid ligament Muscles of the neck Platysma Is the only cutaneous muscle in human body under the skin Attachments superiorly inf border of mandible and skin and is attached to superficial fascia covering pectoralis major and deltoid muscles