Lecturer: Dr. M. SamsamUniversity of Central Florida, Orlando,

Pictures from Platzer atlas and textbook of human anatomy and K. Moore anatomy

And Tortora principles of anatomy, 10th edition

Muscles and regional anatomy of the head and neck and the back

Skull:2 parts:NeurocraniumFacial skeleton

Neurocranium: 8 bonesFrontal X1Parietal X2Temporal X2Occipital X1Sphenoid X1Ethmoid X1

Facial Skeleton: 14 bonesMaxilla X2Nasal X2Zygomatic X2Lacrimal X2Palatine X2Inferior Nasal Conchae X2Mandible X1Vomer 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

Lveolar rocess

Mental Foramen

Foraminae of the skull and their contents:

Muscles of the headThese are mimetic muscle: radiate into the skinof the face and the head, and their contraction causes displacement of the skin.4 groups:A- Muscles of the ScalpB- Muscles in the region of eyelidC- Muscles in the Nasal regionD- Muscle of the Mouth region

A- Muscles of the Scalp:

Epicranius Muscle: (Occipitofrontalis)Has 2 bellies: Frontal (3), Occipital (2), and in between, the Galea Aponeurotica (1).

Temporoparietalis M. (5)

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 (1), Palpebral (2) andLacrimal (3).Function: produces folds in lateral angle of the eye, expression of Worry and concern (C).

Corrugator supercilli (7):Pulls the skin and eyebrow down and medially.Produces vertical folds. Protects against light.Pathetic pain muscle. Thinker’s brow expression (D)

Innervation: All mimetic muscles by Facial (CNVII) N.

Mimetic muscles in the region of the mouth1- Orbicularis Oris M.:Function: its contraction closes the mouth.Strong contraction gives a sucking shape. Expression of reserve (D).

2- Buccinator M.: Quadrilateral in shape.Origin: mandible at 1st or 2nd molar region.Forms the pterygomandibular raphe (3).Extends to angle of the mouth and forms thelateral wall of its vestibule.Function: enables air to be blown out of themouth. Pulls angle of the mouth laterally.Keeps the mucous membrane of the cheek free of folds. Contraction gives expression of satisfaction (E).

Mimetic muscles in the region of the mouth

4- Zygomaticus Major:Origin: zygomatic bone. Insertion: angle of mouth.Function: lifts the corner of the mouth upward,giving expression of laughter or pleasure (F).

5- Zygomaticus Minor:Origin: zygomatic bone Insertion: nasolabial groove.

6- Risorius: (laughing muscle) Function: together woth zygomatic major itproduces the nasolabial folds.Its contraction gives expression of Action (G).

7- Levator labii superioris:Origin: Infraorbital margin to skin of upper lip.

Mimetic muscles in the region of the mouth8- Lavator anguli oris:It lifts the angle of the mouth,Giving expression of self confidence (8).

9- Depressor anguli oris:Function: pulls the angle of the mouthdownwards and produces expression of sadness (I).

10- Depressor labii inferioris:It pulls the lower lid down, giving expression of perseverance (K).

11- Mentalis: Produces: chin-lip furrow, giving expression of doubt and indecision (L).

12- Platysma

All mimetic muscles are innervated by facial N. (CNVII)

Muscles of Mastication:Masseter (1), temporalis (2), Lateral (3) and medial pterygoid (4)

***All Innervated by Mandibular nerve (CNV/3).***Develop from 1st branchial arch.

CNV= cranial nerve 5 (trigeminal nerve). It has 3 branches: ophthalmic, maxillaryand mandibular1- Masseter M:Origin: Zygomatic arch (5)Insertion: masseteric tuberosity of mandible (6)Has 2 parts:7- Superficial part (oblique fibers)8- Deep part (vertical fibers)Function: powerfully closes the jaw by elevating the mandible. NN: Masseteric N CNV/3.

2- Temporalis M:Origin: temporal fossa (9) as far as inf temp line.Insertion: by a strong tendon to coronoid process of mandible and mandibular ramus (11).Function: strongest elevator of lower jaw.NN: deep temporal N CNV/3.

Muscles of Mastication:Masseter (1), temporalis (2), Lateral (3) and medial pterygoid (4)

Lateral pterygoid M (3):Has 2 parts (12 and 14)Function: mandibular movements (guiding muscle).NN: lateral pterygoid N CNV/3.

Medial Pterygoid M (4):Runs at right angles to the lateral pterygoid M.Has 2 partsAngle of mandible is between this muscle and the masseter M. Function: elevates mandible andpushes 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 (2) from ext. carotid passes it anastomose with dorsal nasal A. (4) comingfrom Ophthalmic A.Forehead is supplied by supratrochlear A. (8)and supraorbital (9) A., both from ophthalmic A.

Facial vein (10) anastomoses via Angularvein (11) With dorsal nasal vein. ***This anastomoses is extremely importantsince this allows a direct connection to Cavernous sinus, through which, infectionseg: from a furuncle on the lip, may get into skull.

All mimetic muscles are innervated by branchesof facial N: 13- temporal branch, 14- zygomatic15- buccal branch and 16- 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 (17) and supraorbital (18).

Maxillary nerve: supplies lower eyelid,Cheek, lateral nasal, upper lip and anteriorTemporal regions by Infraorbital N. (22).

Mandibular N: lower lip over mandible (not angle) and chin by mental N (23).Auriculotemporal N (24) supplies skin onMandible ramus, concha of auricle andMost part of ext. layer of tympanic memb.

Sensitivity of the 3 branches of trigeminal Ncan be tested by pressing nerves 18, 22 and 23.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 mandibularnerves. 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 beincluded with the bonyskeleton 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. borderof mandible and skin, and is attachedto superficial fascia covering pectoralis major and deltoid muscles inferiorly.

*Action: brings down corners of themouth, expressing sadness.

*Innervation: Facial N. (VII) (cervical branch)*Injury to this nerve leads to paralysis of platysma (skin falls away from the neck by folds).

*Careful sutures of the skin should be made in surgery of the neck region.

Cranial muscle inserted on the Shoulder girdle:

1- Trapezius M: Repetition: 2- Descending part 3- Transverse part, 4- Ascending partDescending:Origin: from external occipital protuberanceSuperior nuchal line, and Ligamentum nuchaeInsertion: lateral third of clavicleTransverse part: from C7-T3 spinous processInserted to: clavicle and scapula (acromion)Ascending: from T3-T12 spinous processInsertion: spine of the scapula*Function: elevation, retraction and rotation of scapula.Helps in adduction and slight elevation of arm*Innervation: spinal root of Accessory nerve (CNXI) and C3-C4 (propioception)

14- Sternocleidomastoid MOrigin: sternum (15) and clavicle (16)Insertion: Mastoid process and sup. nuchal lineFunction: unilateral contraction turns the headto opposite side and bends it ipsilaterally.Bilateral contraction: lifts the head. Also functions in respiration.Innervation: Accessory nerve (CNXI) and C2-C3

**Accessory nerve Examination

**Congenital and Spasmodic Torticollis (Wry neck)

Congenital Torticollis:Most common type of Torticollis.Fibromatosis (fibrous tissue tumor) of Sternocleidomastoid M.Head turns to the side and face awayfrom the affected side.Leads to stifness of the neck due to fibrosisand shortening of the sternocleidomastoid.Injury during delivery may also result in Torticollis.(muscle tear and hematoma leads to fibrosis)Therapy: division of the muscle below XI nerveor from its distal attachment.

**Spasmodic Torticollis (Wry neck)

SpasmodicTorticollis:Cranial dystonia (abnormal tonicity)Between 20-60 years of age. Unknown cause.May involve bilateral neck muscles especiallythe Sternocleidomastoid M.Unilateral deviation of the head.(turning, tilting, flexion or extension of the neck)May involve other muscles in the body.Therapy: myotomy or also section of the spinalAccessory N. and upper cervical ant. roots

**Infrahyoid muscles:Omohyoid, Sternohyoid,Sternothyroid and Thyrohyoid

*2-4) Omohyoid muscleHas an Inferior and a superior bellyInf. Belly:Origin: Upper border of scapula near the scapular notch.Sup. Belly: inserted to the lower border of the body of the Hyoid bone.A fascial sling connects it to the clavicle.*Action: fascia tensor and dilates internalJugular vein lying beneath it.(this aids to return of blood to the heart)Opens the mouth and helps in lateral flexion of the head.

*Innervation: Most Infrahyoid muscles areinnervated by cervical Ansa (C1-C3).

Infrahyoid muscles: Continued

1-3) Sternohyoid M.:Origin: Post. Surface of manubrium andSterno-clavicular jointInsertion: Body of hyoid bone (inner surfaceand laterally).4-6) Omohyoid M.7-9) Sternothyroid: deeper to sternohyoidOrigin: post. Surface of manubriumInsertion: oblique line of thyroid cartilageIt covers the thyroid gland.10-11) Thyrohyoid M.: Continuation of Sternothyroid M.Origin: oblique line of thyroid cartilageInsertion: inner surface of body (laterally) and lower margin of greater horn.Innervation: C1, before giving the branch tocervical ansa.*Action: All infrathyroid muscles work togetherto approximate thyroid cartilage to hyoid bone.When mouth is open, they stabilize laryngeal cartilages and the hyoid bone.

Suprahyoid muscles:Digastric, Stylohyoid,Myelohyoid and Geniohyoid MM.

**Digastric M.:Origin: Anterior belly: from mandiblePosterior belly: Mastoid notch of temporal boneInsertion: intermediate tendon to body and greater horn of hyoid bone.Function: Raising hyoid and stabilizing it in speaking and swallowing,depressing the mandible.**Innervation: Ant. Belly: V/3, trigeminal N. (from nerve to myelohyoid) and post. belly: VII, facial nerve. Stylohyoid M.:Origin: Styloid process of temporal boneInsertion: body of hyoidFunction: elevates and retracts hyoid bone, elongates floor of the mouth.Innervation: VII, facial N. (cervical branch)

Suprahyoid muscles:continued

Myelohyoid, Geniohyoid,Stylohyoid andDigastric muscles.

*Myelohyoid M.: Origin: mandible, Insertion: body of hyoidFunction: Elevates hyoid and floor of themouth and tongue in swallowingand speaking.*Innervation: V/3 (myelohyoid N. from inf. Alveolar N.)*Geniohyoid M.: Origin: mandible, Insertion: body of hyoidFunction: pulls the hyoid anterosuperiorly,shortens floor of the mouth and widens pharynx.*Innervation: C1 via hypoglossal nerve

Atlas:Submandibular region:

Look at the relation between Hyoglossus and Myelohyoid Muscles, the Lingual nerve, Submandibular gland, duct, and

ganglion and the Hypoglossal nerve

Atlas:

12- Geniohyoid M.10- Myelohyoid M.15- Ant. Belly of Digastric M.14- Genioglossus (cut)

Atlas:

2- Hyoglossus8- Geniohyoid9- Myelohyoid10- Ant. Belly of Digastric5- Stylohyoideus4- Styloglossus1- Genioglossus

Paravertebral and Scalene musclesParavertebrals:Rectus Capitis Ant., Logus Capitis and Longus Colli.Rectus capitis: (1-3)Helps to flex the head. NN: Cervical Plex.(C1)

Longus Capitis: (4-6) Bend the head forward and unilateral actionturns the head sideways.NN: Cervical Plexus(C1-4).

Longus Colli: (7, 8, 9) Action: unilateral contraction bends and turnscervical column to the side. Also bend the cervical spine forwards. NN: cervical and brachial Pl. (C2-C8)

Scalene musclesMost important muscles for quiet inspirationThey lift the first 2 pairs of ribs (sup part of thorax).Unilateral contraction tilts cervical column to one side.Scalene Anterior (17):Scalene Medius (20):Scalene Posterior (23): NN: Brachial plexus (C4-C8).

Scalenus minimus M. may be present in 30%.

26- Scalene opening: brachial plexus and subclavian artery pass through.

A

Occipital (Omotrapezoid) triangle:

Floor: Splenius Capitis (17), Lavator Scapulae (16), Post. Scalene (15)and Middle Scalene (14). *Content: Cervical Plexus.Accessory Nerve comes from behind the Sternocleidomastoid M.

It divides the supraclavicular region to a Care free and careful zone. 12- superficial cervical Artery13- Anterior Scalene M.

***Scalene gap:Formed between scalene Anterior and Middleand 1st rib, in which run the Brachial plexus (18)and Subclavian Artery (19).

21- Phrenic nerve. 22- Suprascapular N.23- Long Thoracic N. 24- Dorsal Scapular N.25- Cervical lymph node

A

Cervical Plexus:Atlas, only look

1- anterior rectus capitis2- Lateral rectus capitis3- Longus Colli4- Ant. Scalene M.5- Middle Scalene M.6- Deep Ansa Cervicalis7- Hypoglossal nerve8- upper root of cervical ansa9- Thyrohyoid muscle10- Inf. root of cervical ansa11- Omohyoid M.12- Sternothyroid M.13- Sternohyoid M.15- Lesser Occipital N.16- Greater auricular N.17- Transverse Cervical N.18- Supraclavicular nerves19- Phrenic nerve.

Triangles of the Neck:

Anterior Triangle:Submandibular T.Carotid T.Muscular T.Submental T.Borders: Posterior (lateral) : SternocleidomastoidSuperior: mandibleAnterior: midline of the neck

Posterior Triangle:Occipital T.Omoclavicular T.

Carotid Triangle:Borders: Super: Post. belly of DigastricMed: Sup. Belly of Omohyoid (2)Lat: Sternocleidomastoid (1)

Skin innervat.: cervical plexusContent:External jugular vein andSuperficial cervical fasciaInternal jugular vein (9) and Common facial vein (6)Common carotid A. (10)Carotid Sinus (11)12- Internal carotid A.13- External carotid A.29- Vagus nerve (behind and in between vessels)24- descending branch of XII(upper root of cervical ansa)runs above the carotid sheath.18- Hypoglossal N.

Hypoglossal nerve

External Carotid A.Common Carotid A.

internal Jugular V.

Vagus N.Subclavian A.

Brachial plexus

Common facial V.

internal Jugular V.

Superior cervical sympathetic ganglion

internal Jugular V.

Big vessels in the neck:

Internal jugular vein puncture:

Thyroid Gland:Body's largest endocrine glandIs deep to sternothyroid and sternohyoid M

At C5-T1 level. It has a capsuleand externally covered by a sheath.Consists of an isthmus (1), whichunites the lobes.A right lobe (2) and a left lobe (3).Pyramidal lobe:A remnant of thyroglossal ductmay persist in the middle partof thyroid (50%). Ectopic Thyroid

****Function:Produces Thyroxin which controlsthe rate of metabolism of the body, and Calcitonin controlling Ca++

metabolism.

Blood supply:Superior (8) and inferior (9) thyroidal artery

Goiter:Enlargement of Thyroid gland (nonneoplasticand noninflammatory). Usually not upward shift.Endemic in areas deficient in Iodine in food. Swelling in the neck which may disturb trachea,esophagus and/or laryngeal nerves.Exophthalmic goiter is due to excessive productionof thyroxin.

Thyroidectomy:Removal of thyroid due to cancer.Subtotal due to preservation of Parathyroid glands and recurrent as well as superior laryngeal nerves.Inadvertent removal of parathyroid glands lead to tetany, severe convulsion and muscle spasm due to decrease in serum Ca++ and may lead to immediate respiratory failure.

Parathyroid glands:Usually 4, one upper and one lower gland per each thyroid lobe.

They are external to thyroid capsule and internal to the connective tissue sheath.Function: Produce parahormon, controlling the metabolism of P and Ca++.