The Head

Chapter 8 The Head



I. Skull (Figures 8-1 to 8-4)



• Consists of neurocranium and viscerocranium

A. Neurocranium

1. Overview


a. Encloses cranial cavity, which houses brain and meninges

b. Formed by cranial base and cranial vault; roof of cranial vault is calvaria

c. Formed by eight bones: paired parietal and temporal bones and unpaired frontal, occipital, ethmoid, and sphenoid bones

2. Temporal bones


a. Squamous part

• Includes mandibular fossa and articular tubercle (articular eminence) for articulation at temporomandibular joint

b. Tympanic part

• Forms floor and anterior wall of external acoustic meatus

c. Mastoid part


(1) Contains mastoid air cells

(2) Includes mastoid process, which develops after birth

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8-1 Skull, anterior view. Lower figure shows close-up view of right orbit with head rotated slightly toward left side.


(From Netter, F H: Atlas of Human Anatomy, 4th ed. Philadelphia, Saunders, 2006, Plate 2.)


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8-2 Skull, lateral view. Upper figure shows temporal fossa outlined by large oval dashed line. Clinically important landmark pterion, which is outlined by smaller oval dashed line, is located within temporal fossa. Lower figure shows infratemporal fossa of deep face outlined by dashed line following removal of zygomatic arch and mandible. Infratemporal fossa communicates medially with pterygopalatine fossa through pterygomaxillary fissure (see Section VIII).


(From Netter, F H: Atlas of Human Anatomy, 4th ed. Philadelphia, Saunders, 2006, Plate 4.)


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8-3 Skull lateral radiograph. Pituitary fossa = 26 = 1; anterior clinoid process = 2; posterior clinoid process = 3; sphenoidal sinus = 4; ethmoidal air cells = 5; greater wing of sphenoid = 6; mastoid air cells = 7; frontal sinus = 8; grooves for middle meningeal vessels = 9; coronal suture = 10; lambdoid suture = 11; coronoid process of mandible = 12; palatine process of maxilla = 13; anterior arch of atlas = 14; dens of axis = 15.


(From Weir, J, Abrahams, P: Imaging Atlas of Human Anatomy, 3rd ed. London, Mosby Ltd., 2003, p 2, a.)


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8-4 Skull base, inferior view.


(From Netter, F H: Atlas of Human Anatomy, 4th ed. Philadelphia, Saunders, 2006, Plate 8.)



The temporal bone is fractured in 75% of skull base fractures.


d. Petrous part

• Contains inner ear, part of middle ear, and carotid canal


Fractures of the petrous portion of the temporal bone often result in leakage of cerebrospinal fluid (CSF) from the ear (CSF otorrhea) and bruising over the mastoid process (Battle sign). The facial and vestibulocochlear nerves may be injured and hemorrhage may occur from a torn internal carotid artery.



Petrous temporal bone fracture causes CSF otorrhea and the Battle sign.


3. Frontal bone


a. Forms forehead and roof of orbit

b. Contains paired frontal sinuses

c. Develops as two bones separated by metopic (interfrontal) suture, which is usually fused by 8th year but remains in 8% of population


An unfused metopic suture between the frontal bones can be mistaken for a skull fracture.


4. Occipital bone



• Consists of basilar, squamous, and paired lateral parts enclosing foramen magnum

a. Basilar part (basioccipital)


The foramen magnum is the opening in the occipital bone where the spinal cord is continuous with the brainstem.


• Articulates with body of sphenoid at former site of sphenooccipital synchondrosis, which is important in skull growth

b. Squamous part

c. Lateral part

• Includes occipital condyle, condylar fossa and canal, and hypoglossal canal

5. Ethmoid bone


A fracture of the cribriform plate produces leakage of CSF from the nose (rhinorrhea).



a. Cribriform plate


(1) Roof of nasal cavity and central floor of anterior cranial fossa

(2) Perforated by olfactory foramina for olfactory nerve fibers


The olfactory nerves traverse the cribriform plate to reach the nasal cavity.


b. Perpendicular plate

• Projects inferiorly from cribriform plate to contribute to nasal septum

c. Ethmoidal labyrinth

• Encloses posterior, middle, and anterior ethmoid air cells (see Figure 8-3)

• Forms superior and middle nasal conchae on lateral wall of nasal cavity and orbital lamina on medial wall of orbit

6. Sphenoid bone


a. Body (see Figure 8-3)

• Contains paired sphenoidal sinuses inferior to sella turcica of middle cranial fossa


The sella turcica houses the pituitary gland.


b. Lesser wing

• Includes optic canal, anterior clinoid process, and superior boundary of superior orbital fissure

c. Greater wing


(1) Contributes to roof of infratemporal fossa and floor of middle cranial fossa

(2) Contains foramina rotundum, ovale, and spinosum

d. Pterygoid process


(1) Consists of medial and lateral pterygoid plates

(2) Hamulus from medial plate serves as pulley for tensor veli palatini muscle to tense soft palate and also gives attachment to pterygomandibular raphe


The skull may fracture opposite the site of impact.



Skull fractures may occur opposite the point of impact. Skull fractures are frequent in the temporoparietal region because the bone there is thinnest. Fractures at the pterion may tear the middle meningeal artery, and a depressed fracture may compress the underlying brain. In most depressed fractures, the overlying scalp is lacerated (compound fracture), which predisposes to infection. A blow to the top of the head may fracture the skull base, with related cranial nerve injury, cerebrospinal fluid (CSF) leakage from a dura-arachnoid tear (CSF fistula), or dural sinus thrombosis. A fracture of the petrous temporal bone may cause blood or CSF to escape from the ear (CSF otorrhea), hearing loss, and facial nerve damage. Fracture of the anterior cranial fossa is suggested by anosmia, periorbital bruising (raccoon eyes), and CSF leakage from the nose (CSF rhinorrhea).



The skin is broken in a compound fracture with a danger of infection.


7. Sutures and landmarks of neurocranium (see Figures 8-1 to 8-4)


a. Bregma


(1) Point at which sagittal and coronal sutures meet in adult

(2) Site of anterior fontanelle, the “soft spot” of an infant’s head


The anterior fontanelle is used to assess ossification, hydration, and intracranial pressure.


b. Lambda


(1) Point at which sagittal and lambdoidal sutures meet

(2) Site of neonate’s posterior fontanelle

c. Pterion




• Site of anterolateral fontanelle where middle meningeal artery usually grooves internal surface of bone (see Figures 8-3 and 8-5)

8. Development of skull


a. Overview


(1) Cranial base (chondrocranium) develops mainly by endochondral ossification.

(2) Cranial vault and facial skeleton develop by intramembranous ossification

(3) Sutures are important sites of growth and allow bones to overlap (molding) during birth.


The skull deformity of craniosynostosis may cause increased intracranial pressure.


b. Craniosynostosis (Table 8-1)


(1) Sutures fuse prematurely, resulting in skull deformity.

(2) Growth is restricted perpendicular to prematurely fused sutures, and compensatory overgrowth occurs at open sutures.

(3) May produce increased intracranial pressure from skull deformity

TABLE 8-1 Skull Deformities in Craniosynostosis























Deformity Suture(s) Involved Description
Scaphocephaly Sagittal suture Long, narrow skull
Oxycephaly Coronal suture, bilateral fusion Short, tall, wide skull
Plagiocephaly Coronal or lambdoid suture, unilateral fusion Asymmetric skull with forehead protruding on one side and flattened on other
Trigonocephaly Metopic suture Wedge-shaped forehead


Premature sagittal suture fusion causes scaphocephaly, the most common form of craniosynostosis.



Craniosynostosis results in a permanent skull deformity that is correctible only by surgery. An asymmetric skull not resulting from premature suture fusion (deformational or positional plagiocephaly) and treatable by conservative means may result from in utero cramping, infant sleep position, or congenital torticollis. The recommendation to position sleeping infants on their backs to reduce the risk of sudden infant death syndrome (SIDS) has dramatically increased the incidence of deformational plagiocephaly.



Synostotic plagiocephaly must be distinguished from reversible deformational plagiocephaly resulting from in utero factors or infant sleep position.


c. Anterior fontanelle


(1) Present at birth; closes at age 9-18 months

(2) Diminished size or absence at birth may indicate craniosynostosis or microcephaly.

d. Posterior fontanelle


(1) Present at birth; usually closes by 2 months of age

(2) Persistence suggests underlying hydrocephalus or congenital hypothyroidism.


A persistence of the anterior or posterior fontanelle may result from hydrocephalus, congenital hypothyroidism, or rickets.


9. Major apertures of neurocranium (Figure 8-5; Table 8-2)

B. Viscerocranium

1. Maxilla


a. Paired bone that joins at midline intermaxillary suture to form upper jaw

b. Has body that contains maxillary sinus and contributes to walls of nasal cavity, orbit, and infratemporal fossa

2. Zygomatic bone


a. Paired bone that forms prominence of cheek, most of lateral orbital margin, and anterior boundary of temporal fossa

b. Helps form zygomatic arch

3. Lacrimal bone (paired)



• Contributes to medial orbital wall at fossa for lacrimal sac

4. Palatine bone (paired)


a. Horizontal plate fuses anteriorly with palatine process of maxilla to form bony palate

b. Perpendicular plate forms part of lateral wall of nasal cavity, medial wall of pterygopalatine fossa, and floor of orbit

5. Inferior nasal concha (paired)



• Independent bone of lateral nasal wall overlying inferior meatus

6. Vomer



• Forms posterior inferior part of nasal septum between choanae

7. Mandible (Figure 8-6)


a. Body


(1) Formed by two halves fused in midline at mental symphysis

(2) Alveolar process to hold mandibular teeth

(3) Mylohyoid line that separates sublingual and submandibular fossae

b. Ramus


(1) Superior coronoid and condylar processes separated by mandibular notch

(2) Features mandibular foramen bordered by lingula on medial surface

II. Scalp and Face

A. Scalp (Figure 8-7)

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8-5 Cranial fossae and related major nerves and vessels, superior view. Left, Dural venous sinuses; right, nerves and arteries.


(From Netter, F H: Atlas of Human Anatomy, 4th ed. Philadelphia, Saunders, 2006, Plate 104.)


TABLE 8-2 Major Apertures of Neurocranium



























































Aperture Communication Between Traversed by
Cribriform plate Nasal cavity and anterior cranial fossa Olfactory nerves
Optic canal Middle cranial fossa and orbit Optic nerve, ophthalmic artery
Superior orbital fissure Middle cranial fossa and orbit Oculomotor, trochlear, ophthalmic, and abducens nerves; ophthalmic vein(s)
Foramen rotundum Middle cranial fossa and pterygopalatine fossa Maxillary nerve
Foramen ovale Middle cranial fossa and infratemporal fossa Mandibular nerve, accessory meningeal artery, lesser petrosal nerve
Foramen spinosum Middle cranial fossa and infratemporal fossa Middle meningeal artery, meningeal branch of mandibular nerve
Foramen lacerum Middle cranial fossa and base of skull Closed in life by cartilage transmitting only small vessels; sometimes defined as including opening of carotid canal
Carotid canal Base of skull and middle cranial fossa Internal carotid artery and plexus
Internal acoustic meatus Posterior cranial fossa and facial canal Facial nerve, nervus intermedius, vestibulocochlear nerve
Stylomastoid foramen Facial canal and base of skull Facial nerve
Jugular foramen Posterior cranial fossa and base of skull Glossopharyngeal, vagus, and accessory nerves; internal jugular vein, inferior petrosal sinus
Foramen magnum Posterior cranial fossa and base of skull Brainstem, vertebral arteries and veins, spinal arteries, spinal portion of accessory nerve
Hypoglossal canal Posterior cranial fossa and base of skull Hypoglossal nerve

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8-6 Mandible. Anterolateral superior view (upper figure). Left posteroinferior view (lower figure).


(From Norton, N S: Netter’s Head and Neck Anatomy for Dentistry. Philadelphia, Saunders 2007, p 47.)


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8-7 Layers of the scalp and the scalp’s connection to intracranial structures (superior sagittal sinus) via emissary veins.


(From Norton, N S: Netter’s Head and Neck Anatomy for Dentistry. Philadelphia, Saunders 2007, p 162.)



The SCALP acronym describes the five layers of the scalp.


1. Skin

2. Connective tissue



• Dense superficial fascia containing nerves and blood vessels

3. Aponeurosis



• Fibrous epicranial aponeurosis connecting frontalis and occipitalis parts of occipitofrontalis muscle


The first three layers of the scalp detach together in scalping injuries.


4. Loose connective tissue



• Allows three more superficial layers to move over skull surface

5. Pericranium



• Periosteum covering outer surface of bone


In scalping injuries, the loose connective tissue layer is the plane of separation with the superficial three layers detaching together as a unit. The loose connective tissue allows infection to spread across the calvaria and potentially through emissary veins to the skull bones or intracranial dural venous sinuses, producing meningitis and/or septicemia. The dense connective tissue layer prevents retraction of lacerated blood vessels, resulting in profuse bleeding from the rich blood supply. Since the arteries supplying the scalp all ascend into it, bleeding can often be controlled by tying a string around the head above the ears. If the aponeurotic layer is cut in the coronal plane, gaping of the wound occurs due to the pull of the frontalis and occipitalis.



Scalp lacerations bleed profusely due to the lack of vessel retraction and abundant anastomoses.


Since arteries ascend into the scalp, bleeding may be controllable by tying a string around the head.


B. Muscles of Face and Scalp

1. Subcutaneous voluntary muscles (muscles of facial expression) that move skin of face and scalp

2. Develop from mesoderm of second pharyngeal arch and are innervated by facial nerve

C. Nerves of Face and Scalp (Figure 8-8)

1. Cutaneous innervation of face and scalp is from trigeminal nerve (CN V) and cervical spinal nerves (C2, C3).

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8-8 Cutaneous nerves and arteries of the face and scalp. Left, arteries (red); right, nerves (gray).



Cutaneous innervation of the face is from CN V. Motor innervation is from CN VII.


2. Facial nerve (CN VII)


a. Exits stylomastoid foramen to enter parotid gland

b. Posterior auricular nerve motor to posterior scalp muscles

c. Nerve to stylohyoid and posterior digastric muscles

d. Branches within parotid gland


(1) Temporal branches supply muscles of forehead and temple

(2) Zygomatic branches supply orbicularis oculi and muscles of the upper lip and nose.

(3) Buccal branches supply muscles of upper lip and angle of mouth

(4) Marginal mandibular branch supplies muscles of lower lip and angle of mouth

(5) Cervical branch supplies platysma muscle


To Zanzibar By Motor Car: temporal, zygomatic, buccal, mandibular, cervical branches of CN VII.



Terminal branches of CN VII may be injured by parotid cancer or by surgery to remove a parotid tumor (Figure 8-9). An infant’s facial nerve may be injured during a forceps delivery because the mastoid process has not yet developed and the stylomastoid foramen is relatively superficial. Bell palsy is idiopathic unilateral facial paralysis.


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8-9 Axial CT showing tumor of left parotid gland. Parotid tumors or surgery to remove them may damage the facial nerve.


(From Drake, R, Vogl, W A, Mitchell, A: Gray’s Anatomy for Students, 2nd ed. Philadelphia, Churchill Livingstone, 2010, Figure 8.57.)



The facial nerve is vulnerable to injury during forceps delivery of an infant or parotid surgery in an adult.



Symptoms associated with lesions of CN VII are determined by the location of the lesion. Facial muscles are always paralyzed, although the extent and severity vary. Of particular concern is the inability to close the eyelids, which may cause drying and ulceration of the cornea. A lesion within the facial canal will also affect taste from the anterior two-thirds of the tongue carried by the chorda tympani.



Bell palsy is unilateral paralysis of all the facial muscles from an idiopathic facial nerve lesion.


3. Cutaneous branches of trigeminal nerve


Intense, stabbing pain over the face, usually in the distribution of the maxillary and/or mandibular divisions of the trigeminal nerve, characterizes trigeminal neuralgia (tic douloureux). Attacks are precipitated by stimulation of trigger zones. Usual sensory and motor functions are unaffected in most patients. The cause may be compression of the sensory root by an aberrant blood vessel The pain may be alleviated by some anticonvulsant medications or by microvascular decompression, selective radiofrequency ablation of the trigeminal ganglion or sensory root, or glycerol injection.


Sweating and flushing of the skin along the distribution of the auriculotemporal nerve characterize auriculotemporal nerve syndrome (Frey syndrome). The syndrome is an abnormal response to eating that replaces salivation on the affected side due to anomalous regeneration of secretomotor fibers to sweat glands after parotid surgery.



Tic douloureux is intense paroxysms of pain along the maxillary and/or mandibular divisions of CN V.


4. Cutaneous branches of cervical spinal nerves to head


a. Great auricular nerve (anterior rami of C2, C3)

b. Lesser occipital nerve (anterior ramus of C2)

c. Greater occipital nerve (posterior ramus of C2)


The arteries of the face and scalp come mainly from the branches of the external carotid artery.


D. Blood Vessels of Face and Scalp (see Figure 8-8)

1. Superficial temporal artery



• Ascends anterior to auricle with auriculotemporal nerve (V3)


Temporal arteritis is the most common vasculitis in adults.



Temporal arteritis is the most common vasculitis in adults, usually occurring after age 50. Blood flow is diminished. Inflammation of the superficial temporal artery causes pain overlying the vessel and pain when opening and closing the jaw as the inflamed vessel is stretched. The ophthalmic artery is also frequently involved, often resulting in blindness. Patients are placed on high doses of corticosteroids.


2. Maxillary artery



• Mental, buccal, and infraorbital arteries are distributed with corresponding nerves.

3. Facial artery


a. Passes deep to submandibular gland and over lower border of mandible to ascend toward medial angle of eye


The inferior border of the mandible anterior to the masseter is the pressure point to control facial artery bleeding.


b. Branches in face include superior and inferior labial, lateral nasal, and angular arteries.

4. Occipital artery



• Distributed to scalp with greater occipital nerve

5. Posterior auricular artery



• Supplies back of auricle and scalp above and behind ear

6. Ophthalmic artery



• Gives branches that become cutaneous around eye, including supraorbital, supratrochlear, lacrimal, and dorsal nasal arteries


The involvement of the ophthalmic artery in temporal arteritis may result in blindness.



Extensive collateral circulation exists between the branches of the external carotid arteries in the face and neck. Collateral circulation between the internal and external carotid arteries is provided by anastomosis of the dorsal nasal artery (from the ophthalmic artery) with the angular artery (from the facial artery).


7. Facial vein (see Figure 7-6)


a. Begins as angular vein near medial angle of eye and parallels facial artery

b. Connects with cavernous sinus via ophthalmic veins and deep facial vein-pterygoid plexus


The middle third of the face is a “danger area” because infections there may produce thrombophlebitis of the facial vein that can spread to the cavernous venous sinus via the pterygoid venous plexus or ophthalmic veins. Septicemia leads to meningitis and cavernous sinus thrombosis, both of which can cause neurological damage and are life-threatening.



The middle third of the face is a “danger area” because infection can spread to the cavernous sinus.


III. Parotid, Temporal, and Infratemporal Regions

A. Parotid Gland

1. Overview


a. Extends superficially over ramus of mandible and masseter (superficial lobe) and deep to ramus (deep lobe)

b. Enclosed by tough parotid fascia from investing layer of deep cervical fascia

2. Structures partially embedded within parotid gland


a. Facial nerve and its terminal branches

b. Retromandibular vein and its originating tributaries

c. External carotid artery and its terminal branches

d. Parotid lymph nodes

3. Parotid duct (Stensen’s duct)



• Crosses masseter superficially and pierces buccinator and cheek mucosa to open opposite upper second molar


Salivary gland stones can cause painful glandular swelling while eating.



A salivary gland stone (sialolith) may block the parotid duct, causing painful swelling of the gland that is worse at mealtimes or after eating a sour pickle. Surgical removal of the calculus may be required. Parotid stones are less common than submandibular duct stones.


4. Innervation of parotid gland


a. Parasympathetic innervation (secretomotor)


Preganglionic parasympathetic fibers of IX to parotid gland synapse in the otic ganglion



(1) Preganglionic parasympathetic fibers traverse tympanic branch of glossopharyngeal nerve (CN IX), tympanic plexus, and lesser petrosal nerve to otic ganglion

(2) Postganglionic parasympathetic fibers from otic ganglion are distributed to parotid gland via auriculotemporal nerve (V3).

b. Sympathetic innervation (vasomotor)




• Postganglionic sympathetic fibers from superior cervical ganglion are distributed via periarterial external carotid plexus


Mumps is a highly contagious viral infection of the parotid gland. Swelling of the gland within its tough capsule causes intense pain, which is exacerbated by compression between the mandibular ramus and mastoid process during chewing. Infection may involve the testes (orchitis), resulting in sterility, or less commonly cause meningitis or pancreatitis. Since salivary glands contain amylase, serum amylase often is markedly increased in mumps.



Mumps may be complicated by orchitis, producing sterility.


B. Temporal Fossa

1. Bounded by temporal lines, frontal process of zygomatic bone and zygomatic process of frontal bone, and zygomatic arch

2. Floor formed by parts of greater wing of sphenoid, squamous temporal, frontal, and parietal bones meeting at pterion

3. Contains temporalis muscle, deep temporal nerves and vessels (deep to temporalis muscle), zygomaticotemporal and auriculotemporal nerves, temporal branch of facial nerve, and superficial temporal vessels

C. Infratemporal Fossa

1. Overview


a. Bounded by posterior surface of maxilla, greater wing of sphenoid, lateral pterygoid plate, and ramus of mandible

b. Communicates with orbit, pterygopalatine fossa, and middle cranial fossa

c. Contains mandibular nerve (V3), maxillary artery, pterygoid venous plexus, pterygoid muscles, temporalis tendon, chorda tympani, and otic ganglion

2. Muscles of mastication (Figure 8-10; Table 8-3)



• Develop from first pharyngeal arch and are innervated by mandibular nerve (V3)

3. Temporomandibular joint (TMJ)


a. Paired synovial joint between mandibular condyle (head) and articular tubercle (articular eminence) of temporal bone

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8-10 Muscles of mastication. A, Masseter and temporalis shown in lateral view. B, Masseter removed to show temporalis insertion. C, Masseter, temporalis, part of ramus of mandible, and zygomatic arch removed to show lateral and medial pterygoid muscles.


(From Netter, F H: Atlas of Human Anatomy, 4th ed. Philadelphia, Saunders, 2006, Plates 54 and 55.)



TABLE 8-3 Muscles of Mastication

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TMJ disorders are often due to grinding the teeth.



Temporomandibular joint disorders occur in 15% of the population. They often result from clenching the jaws and grinding the teeth (bruxism) due to stress, but the TMJ is also subject to the same diseases as other synovial joints, including rheumatoid arthritis, infection, and neoplasia.


b. Joint cavity subdivided by articular disc into upper compartment for gliding movements and lower compartment for hinge movements

c. Differs from other synovial joints in having articular surfaces covered by fibrous tissue rather than hyaline cartilage

d. Fibrous capsule reinforced by lateral temporomandibular ligament

e. Innervated by auriculotemporal and masseteric nerves (V3)


The lateral pterygoid pulls the head of the mandible and articular disc forward onto the articular tubercle when opening the jaw.


f. Sphenomandibular ligament


(1) Thin band from spine of sphenoid bone to lingula of mandible

(2) Remnant of first pharyngeal arch cartilage (Meckel cartilage)

g. Stylomandibular ligament


(1) Thickened parotid fascia between styloid process and mandible near angle, separating parotid and submandibular salivary glands

(2) Helps limit extreme protrusion of mandible and spread of infection between parotid and submandibular glands


Dislocation of the temporomandibular joint occurs when the condyle of the mandible slides too far anteriorly over the articular tubercle and cannot return to the condylar fossa. The jaw is then held in the dislocated position by action of the muscles of mastication. Dislocation may occur when the mouth is opened too far (as during yawning) or when the chin is struck while the mouth is open. A blow to the chin with the mouth closed can drive the head of the mandible posteriorly and superiorly, fracturing the bony auditory canal and/or the floor of the middle cranial fossa.



TMJ may dislocate if the condyle slides too far anteriorly over the articular tubercle.



Ankylosis of the TMJ is unilateral or bilateral loss of movement. It may result from rheumatoid arthritis, infectious agents, neoplasia, or trauma. Pain may be referred to the TMJ by stimulation of abnormal muscle foci (trigger points) in the head and neck.



The TMJ and the ear may refer pain to each other.


4. Maxillary artery (Figure 8-11)


a. Overview


(1) Terminal branch of external carotid artery within parotid gland

(2) Traverses infratemporal fossa superficial or deep to lateral pterygoid muscle to enter pterygopalatine fossa

(3) Divided into three parts in relation to lateral pterygoid

b. Middle meningeal artery


(1) Ascends between roots of auriculotemporal nerve to enter middle cranial fossa through foramen spinosum

(2) Courses between bone and dura mater, supplying both

(3) Anterior branch often grooves bone in region of pterion

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8-11 Maxillary artery. In the upper figure the ramus of the mandible and zygomatic arch have been partially removed. In the lower figure a paramedian sagittal section of the face and removal of the mandible show the course of maxillary artery branches to the nasal and oral cavities. The middle meningeal artery typically ascends between the roots of the auriculotemporal nerve as shown.


(From Netter, F H: Atlas of Human Anatomy, 4th ed. Philadelphia, Saunders, 2006, Plate 40.)



A skull fracture at pterion tears the middle meningeal artery to produce an epidural hematoma.


c. Accessory meningeal artery


(1) Arises from maxillary or middle meningeal artery

(2) Traverses foramen ovale to supply trigeminal ganglion and dura mater

d. Inferior alveolar artery




• Distributed with inferior alveolar nerve to lower teeth, chin, and lower lip

e. Branches to muscles of mastication




• Arise from second part of maxillary artery

f. Posterior superior alveolar artery




• Enters posterior surface of maxilla to supply posterior maxillary teeth

g. Infraorbital artery




• Distributed with infraorbital nerve (V2), giving anterior superior alveolar artery to supply anterior maxillary teeth and middle of face

h. Sphenopalatine artery


(1) Passes medially into nasal cavity through sphenopalatine foramen

(2) Major blood supply to nasal cavity and paranasal sinuses

i. Descending palatine artery




• Descends through palatine canal, dividing into greater and lesser palatine arteries to supply hard and soft palates, respectively

5. Pterygoid venous plexus


a. Formed around maxillary artery and lateral pterygoid muscle

b. Receives tributaries corresponding to branches of maxillary artery


The pterygoid venous plexus may spread infection to the cavernous sinus from an abscessed tooth or the danger area of the face.


c. Coalesces to form maxillary vein, which joins superficial temporal vein to form retromandibular vein

d. Communicates with facial vein, with inferior ophthalmic vein, and with cavernous sinus

6. Mandibular nerve (V3) (Figure 8-12)


a. Overview


(1) Passes from trigeminal (semilunar) ganglion through foramen ovale

(2) Only division of trigeminal nerve to give motor innervation to skeletal muscles; small motor root joins mandibular nerve high in infratemporal fossa

(3) Supplies sensory (general somatic afferent [GSA]) innervation to mandible, temporomandibular joint, face, cheek and tongue, and dura

b. Motor branches


(1) Supply motor (special visceral efferent, branchial efferent) innervation to muscles that develop from first pharyngeal arch

(2) Innervate four paired muscles of mastication: temporalis, masseter, medial and lateral pterygoids

c. Meningeal branch




• Accompanies middle meningeal artery through foramen spinosum to supply dura mater of middle cranial fossa

d. Buccal nerve




• Pierces buccinator muscle, supplying sensation to skin and mucous membrane of cheek and gums

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8-12 Branches of mandibular nerve. In the upper figure the ramus and part of the body of the mandible have been removed to give a lateral view of the mandibular nerve. Part of the inferior alveolar nerve was removed with the mandible. In the lower figure a medial view of the mandibular nerve is shown as it exits the cranial cavity via the foramen ovale to enter the infratemporal fossa. The otic ganglion is closely related to the mandibular nerve.


(From Netter, F H: Atlas of Human Anatomy, 4th ed. Philadelphia, Saunders, 2006, Plate 46.)



The buccal branch of V is sensory, and the buccal branch of VII is motor.


e. Auriculotemporal nerve


(1) Arises by two roots that encircle middle meningeal artery

(2) Ascends in front of ear, supplying external ear and tympanic membrane, temporomandibular joint, and scalp of temporal region

(3) Carries postganglionic parasympathetic fibers from otic ganglion to parotid gland

f. Lingual nerve


(1) Carries general sensation (GSA) from anterior two-thirds of tongue

(2) Joined by chorda tympani carrying preganglionic parasympathetic (general visceral efferent, GVE) fibers to submandibular ganglion and taste (special visceral afferent [SVA]) fibers from anterior two-thirds of tongue

(3) Distal to submandibular ganglion carries postganglionic parasympathetic fibers to sublingual salivary gland; submandibular gland is supplied by direct branches of ganglion

g. Inferior alveolar nerve


(1) Enters mandibular foramen after giving off mylohyoid nerve to supply mylohyoid muscle and anterior belly of digastric muscle

(2) Gives inferior dental and gingival branches in mandibular canal

(3) Divides into incisive nerve to canine and incisor teeth and mental nerve to chin and skin and mucosa of lower lip


Temporary facial paralysis may result from an errant inferior alveolar nerve block.



The mandibular nerve can be blocked in the infratemporal fossa just after it emerges from the foramen ovale. For dental procedures on the mandibular teeth, the inferior alveolar nerve is blocked as it enters the mandibular foramen. The facial nerve or lingual nerve may be blocked or injured by incorrect needle placement during an inferior alveolar injection. Temporary facial paralysis and tongue anesthesia, respectively, may result.



Four paired parasympathetic ganglia in head: otic, submandibular, pterygopalatine, and ciliary


7. Otic ganglion (Table 8-4)


a. Closely related to mandibular nerve just below foramen ovale

b. Receives preganglionic parasympathetic fibers from glossopharyngeal nerve via tympanic branch and lesser petrosal nerve

c. Sends postganglionic parasympathetic fibers to parotid gland via auriculotemporal nerve

IV. Cranial Cavity, Meninges, and Dural Venous Sinuses

A. Meninges

1. Pia mater


a. Fine vascular inner layer inseparable from surface of brain


TABLE 8-4 Autonomic Innervation of the Head

image


Pia mater covers the surface of the brain.


b. Forms sheath around blood vessels as they penetrate brain

c. Normally a transparent membrane unless inflamed as in meningitis

2. Arachnoid mater


a. Transparent intermediate layer applied to inner surface of dura mater

b. Separated from pia mater by subarachnoid space containing cerebrospinal fluid (CSF), but connected to it by delicate arachnoid trabeculae

c. Arachnoid granulations pass CSF into venous blood of superior sagittal sinus and lateral lacunae


Hydrocephalus is excess CSF inside the cranial cavity due to obstructed flow or resorption.

Related posts:

  1. The Neck
  2. The Upper Extremity
  3. The Abdomen
  4. The Pelvis and the Perineum

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Jun 16, 2016 | Posted by in ANATOMY | Comments Off on The Head

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