School of Medical Sciences


Head

Table of contents


Skull


Cranium (Brain case) or Facial skeleton or Neurocranium or Viscerocranium.

Calvaria Cranial base or Cranial Vault or Base of skull or Upper part of brain case.

The 8 Bones of cranium (4 single and 2 paired)

  • Frontal bone (single)
  • Ethmoid bone (single)
  • Sphenoid bone (single)
  • Occipital bone (single)
  • Parietal bone (paired)
  • Temporal bone (paired)

The 14 Bones of facial skeleton (2single and 6 paired)

  • Vomer (single) 
  • Nasal bone (paired) 
  • Lacrimal bone (paired) 
  • Inferior concha (paired) 
  • Palatine bone (paired) 
  • Zygomatic bone (paired)
  • Maxilla (paired)
  • Mandible (single=two halves)

Skull: Exterior views

  1. Norma Verticalis (Superior View)
    Bones: Frontal, Parietals, Occipital (squamous part)
    Sutures: Coronal, Sagittal, Lambdoid, Frontal (Metopic) [occasional]
    Features: Parietal eminence, Bregma, Lambda
    Foramen: Parietal
  2. Norma Frontalis (Anterior View)
    Bones: Frontal, Nasal, Maxilla, Zygomatic
    Features: Supercilary arches, Glabella, Nasion, Orbit, Anterior nasal aperture, Anterior nasal spine
    Foramina: Infraorbital, Zygomaticofacial
  3. Norma Lateralis (Lateral View)
    Bones: Frontal, Parietal, Sphenoid (greater wing), Temporal (squamous part , and zygomatic, mastoid and styloid processes), Occipital, Zygomatic, Maxilla
    Features: Pterion, Superior and Inferior temporal lines, Supramastoid crest, Temporal fossa, Infratemporal fossa, Pterygopalatine fossa
    Foramina: External accoustic meatus, Zygomaticotemporal foramen
  4. Norma Occipitalis (Posterior view)
    Bones: Parietals, Occipital, Temporal, (mastoid part)
    Sutures: Lambdoid, Parietomastoid, Occipitomastoid
    Features: External occipital protuberance, Superior nuchal line, Inferior nuchal line, Inion
  5. Norma Basalis (Inferior View)
    Bones: Maxilla (Palatine processes, alveolar processes), Palatine (Horizontal plate), Sphenoid (Body, greater wings, and medial and lateral pterygoid plates), Temporal (Squamous, petromastoid, and tympanic parts), Occipital (Basilar and squamous parts)
    Features: Incissive fossa, Posterior nasal spine, Pharyngeal tubercle, Pterygoid fossa, Scaphoid fossa, Pterygoid hamulus, Infratemporal crest, Spine of sphenoid, Mandibular fossa, Articular tubercle, Jugular fossa, Styloid process, Occipital condyle, Mastoid process, Mastoid notch (groove for posterior belly of digastric muscle), External occipital crest, Superior and inferior nuchal lines, External occipital protuberance
    Foramina: Incisive Greater and lesser palatine, Foramen ovale, Foramen spinosum, Foramen lacerum, Opening for auditory tube, Carotid canal, Pterygoid canal, Foramen magnum, Hypoglossal canal, Jugular foramen, Stylomastoid foramen, Posterior nasal apertures (choanae)

Skull: Interior

  1. Inner aspect of the calvaria (vault)
    Bones: Frontal, Parietal, Occipital
    Features: Frontal crest, Groove for superior sagittal sinus, Groove for brances of middle meningeal vessels, Depressions for arachnoid granulations
    Foramina: Parietal
  2. Cranial Fossae

    Anterior Cranial Fossa
    Bones: Frontal (orbital plates), Ethmoid (cribriform plate), Sphenoid (lesser wings and jugum)
    Features: Crista galli, Anterior clinoid process
    Foramina: Cribriform plate foramina, Foramen caecum, Nasal slits

    Middle Cranial Fossa
    Bones: Sphenoid (body and greater wings), Temporal (petrous and squamous parts)
    Parietal Features: Sulcus chiasma, Sella turcica, Tuberculum sellae, Hypophyseal fossa, Dorsum sellae, Posterior clinoid processes, Groove (sulcus) for internal carotid artery, Middle clinoid process, Impression for the trigeminal ganglion
    Foramina: Optic canal, Superior orbital fissure, Foramen rotundum, Foramen ovale, Foramen spinosum, Foramen lacerum, Fissures for greater and lesser petrosal nerves

    Posterior cranial fossa
    Bones: Occipital (basillar and squamous parts), Temporal (petrou..s and mastoid parts), Parietal, Sphenoid (body)
    Features: Groove for transverse sinus Groove for sigmoid sinus, Internal occipital crest, Internal occipital protuberance, Clivus
    Foramina: Foramen magnum, Jugular foramen, Hypoglossal (anterior condylar) canal, Internal auditory (acoustic) meatus, Posterior condylar canal

Bones of the Orbit

  1. Margins of the orbit
    Medial: Frontal and maxillary bones
    Superior: Frontal bone
    Lateral: Zygomatic and frontal bones
    Inferior: Zygomatic and maxillary bones
  2. Walls of the orbit
    Medial wall: Maxilla (frontal process), Lacrimal bone, Ethmoid (orbital part), Sphenoid (body)
    Features: Nasolacrimal canal, Anterior and posterior ethmoid foramena
  3. Roof (Superior) wall
    Frontal (orbital plate) sphenoid (lesser wing)
    Features: Lacrimal fossa (for lacrimal gland), Optic foramen, Trochlear fossa
  4. Lateral wall
    Sphenoid (anterior surface of the greater wing), Zygomatic (orbital surface)
    Features: Zygomatic canal (for zygomatic nerve from maxillary nerve)
  5. Floor (Inferior) wall
    Maxilla (orbital surface), Zygomatic bone, Palatine bone (orbital process)
    Features: Infra orbital groove and canal
  • Superior Orbital Fissure: separates the lateral wall from the roof.
  • Inferior Orbital Fissure: separates the floor from the lateral wall.

Pterygopalatine Fossa

Roof: Inferior surface of body of sphenoid, Orbitalprocess of palatine bone, Inferior orbital fissure
Floor: Apposition of anterior and posterior walls of the fossa
Anterior wall: Upper part of posterior surface of maxilla
Posterior wall: Anterior surface of greater wing of sphenoid, Root of pterygoid process, Anterior opening of pterygoid canal
Medial wall: Upper part of perpendicular plate of palatine bone, Orbital and sphenoidal processes of palatine bone, Sphenopalatine foramen

Mandible

  1. Body
    Surfaces (external and internal), Borders (upper and lower), Mental protuberance, Mental tubercle, Mental foramen, Oblique line, Digastric fossa, Mylohyoid line, Submandibular fossa, Sublingual fossa, Mental spines, Mylohyoid groove
  2. Ramus
    Surfaces (lateral and medial), Borders (anterior and posterior), Mandibular notch, Coronoid process, Condylar process, (head and neck of the mandible), Angle of the mandible, Mandibular canal, Lingula

Skull

  • skeleton of head most complex bony structure in body, it encloses brain, houses organs of special senses, and surrounds openings into respiratory and digestive tracts
  • in anatomical position, skull orientated so that inf margin of orbit and sup margin of external auditory meatus are level (orbitomeatal plane, Frankfort plane)
  • Anterior Aspect
    • comprises ant part of calvaria superiorly and skeleton of face inferiorly
    • notable features are forehead, orbits, prominence of cheek, anterior nasal apertures, paired maxillae, and mandible
    • can be divided into five areas: frontal, orbital, maxillary, nasal and mandibular
  • Posterior Aspect
    • formed mainly by paired parietal bones and occipital bone, meet mastoid parts of temporal bones laterally
    • most prominent feature is rounded post pole, occiput, this region often referred to as occipital area
    • external occipital protuberance is median projection, easily palpable at sup end of med furrow of neck
    • centre and most prominent projection called inion
    • curved superior nuchal lines run lat from ext occipital protuberance towards mastoid processes, represent sup limit of post neck, indicated where certain neck muscles attach
    • post part of sagittal suture and lambdoid sutures meet at lambda
  • Superior Aspect
    • oval shaped, broadened post by parietal eminences 
    • superciliary arches of frontal bone from ant limit, zygomatic arches visible laterally four bones united by interlocking sutures
    • two parietal bones joined by sagittal suture
    • frontal and parietal bones joined by coronal suture
    • parietal and occipital bones joined by lambdoid sutures
    • intersection of coronal and sagittal sutures is called bregma
    • vertex, most sup part of skull, located near centre of sagittal suture
    • parietal foramina located in parietal bone on each side of sagittal suture, transmit emissary veins which connect intracranial dural sinuses with veins covering skull
  • Inferior Aspect
    • external surface of cranial base shows maxilla, bony palate, maxillary teeth and zygomatic arches
    • each zygomatic arch formed by union of zygomatic bone and zygomatic process of temporal bone
    • centrally, inf surface of cranial base irregular due to many foramina, processes and articulations, makes it weak and prone to fractures
    • lat, cranial base exhibits temporal bones with prominent mastoid and styloid processes
    • foramen magnum , bordered lat by occipital condyles (articulate with C1), transmits medulla oblongata  
  • Lateral Aspect
    • includes parietal, frontal and parts of temporal and sphenoid bones
    • division of skull into calvaria and facial skeleton clearly shown o calvaria formed by frontal bone (ant), sphenoid and parietal bones (lat), and occipital bone (post)
    • pterion (where all four bone articulate) is important clinical landmark (ant branch of mid meningeal a. lies beside), located in temporal fossa
    • located 2 fingers sup to zygomatic arch, 1 thumb post to zygomatic process of frontal bone
    • other features are external auditory meatus, zygomatic bone, zygomatic arch, mastoid process and mandible
    • mastoid process project ant-inf, med to ear lobe, easily palpable, size varies with muscularity and age (not present at birth, enlarge at puberty), form part of sup attachment of sternocleidomastoid o mental protuberance (of chin) easily visible in most people
  • Internal Aspect
    • bones seen in internal aspect of skull are: frontal, ethmoid, sphenoid, temporal and occipital
    • internal surface of calvaria fairly smooth and concave, particularly from side to side
    • striking features are grooves in parietal bones made by ant branches of mid meningeal blood vessels
    • sutures least distinct on inside because fusion begins ~10 years earlier
    • arachnoid granulations
    • project into venous sinuses (particularly into lacunae of sup sagittal sinus) enough to indent bones of calvaria presents three distinct tiered areas: anterior, middle, and posterior cranial fossae 
  • Walls 
    • thinner in females, young and old
    • tends to be thinnest in areas that are well covered by muscles
    • most bones of calvaria consist of inner and outer layers (tables) of compact bone, separated by layer of spongy diploë (containing red bone marrow)

Bones of Calvaria

  • except for mandible and auditory ossicles bones of skull are joined by rigid sutures
  • cranium is essentially one big complex bone
  • Frontal Bone
    • frontal squama = smooth, board, convex plate of bone forming forehead
    • the two halves halves of frontal squama are divided by metopic (frontal) suture in foetal skulls, begins to fuse during infancy and is not usually visible after 6 years of age
    • frontal bone forms thin roof of orbits
    • just sup to and parallel to each supraorbital margin is bony ridge called superciliary arch, which overlies frontal sinus
    • gently rounded glabella lies between the two arches
    • slightly prominences on each side (sup to superciliary arches) are frontal eminences o supraorbital notch (foramen)
    • (transmits supraorbital vessels and nerve) located in med supraorbital margin articulates with nasal bone at frontonasal suture
    • at point where this crosses internasal suture is an anthropological landmark, nasion
    • this isdepression in root of nose, where it joins cranium
    • also articulates with zygomatic, lacrimal, ethmoid and sphenoid bones
  • Parietal Bones
    • form large parts of wall of calvaria
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Face


  • face extends from margin of hair to chin, from one auricle to or
  • forehead common to both face and scalp
  • skin contains numerous sweat and sebaceous glands and is connected to underlying bones by loose ct
  • superficial fascia lies beneath skin with muscles of facial expression are embedded in it

Sensory Nerves

  • include branches from three division of trigeminal n., which supply skin of face (except for small area over angle of mandible and parotid gland supplied by greater auricular n., C2-3)

Ophthalmic Nerve (V1)

  • superior division of trigeminal nerve
  • wholly sensory and supplies skin derived from frontonasal prominence
  • divides into three branches just before entering sup orbital fissure: nasociliary, frontal and lacrimal

Nasociliary

  • supplies tip of nose through external nasal branch of anterior ethmoidal n.
  • supplies root of nose through infratrochlear n.

Frontal

  • direct continuation of V1
  • divides into two branches: supraorbital (med) and supratrochlear (lat)

Lacrimal

  • smallest of main ophthalmic branches
  • emerges over sup-lat orbital margin to supply the lat part of upper eyelid

Maxillary Nerve (V2)

  • intermediate division of trigeminal nerve
  • three cutaneous branches supply skin derived from maxillary prominence
  • infraorbital n. (large terminal branch) passes through infraorbital foramen and supply skin on lat nose, upper lip and lower eyelid
  • zygomaticofacial n. (small branch) emerges from zygomatic bone through zygomaticofacial foramen to supply skin over zygomatic prominence
  • zygomaticotemporal n. emerges through zygomaticotemporal foramen and supplies skin over temporal region

Mandibular Nerve (V3)

  • inferior division of trigeminal nerve
  • three sensory branches supply skin derived from mandibular prominence, and motor fibres supply muscles of mastication (only division to carry motor fibres)
  • buccal n. emerges deep to ramus of mandible to supply skin of cheek over buccinator, mucous membrane lining and post part of gingival surface
  • auriculotemporal n. passes med to neck of mandible and n turns up, post to it head and ant to auricle, n crosses over root of zygomatic process, deep to superf temporal a., supplies parts of auricle, ext acoustic meatus, tmpanic mebrance and skin in temporal region
  • inf alveolar n. (large terminal branch) enters mandibular canal through mandibular foramen, supplies branches to lower teeth, opposite mental foramen divides into incisive (incisor teeth) and mental (chin) branches lingual n.
    (small terminal branch) supplies general sensory fibres to ant 2/3 of tongue, floor of mouth and mandibular gums

Motor Nerves

  • CN VII (facial n.) supplies platysma, muscles of facial expression, auricular and scalp muscles
  • sole motor supply to muscles of facial expression, taste sensation from ant 2/3 of tongue, and secretomotor to salivary glands (except for parotid)
  • emerges from skull through stylomastoid foramen (between mastoid and styloid processes), almost immediately enters parotid gland, runs superficially, gives off five terminal branches: temporal, zygomatic, buccal, mandibular and cervical
  • emerge from sup, ant and inf margins of parotid gland and spread out like abducted digits

Arterial supply

  • two main arteries supply most of blood to face: facial and superior temporal aa.
  • branches from supraorbital and supratrochlear supply skin of forehead

Facial Artery

  • chief a. of face
  • arises from ext carotid and winds it was to inf mandible just ant to masseter, usually grooving bone, lies superf here and pulsations can easily be felt
  • crosses mandible, buccinator and maxilla, lies deep to zygomaticus major and levator labii superioris
  • branches on face include submental, inferior labial, superior labial, and lat nasal

Superficial Temporal Artery

  • smaller of two terminal branches of ext carotid a.
  • begins within parotid gland, post to neck of mandible, ascends superf to post part of zygomatic process, enters temporal fossa and ends in scalp by dividing into frontal and parietal branches
  • transverse facial a. arises from superf temporal a. before it emerges from parotid gland, crosses face superf to masseter, about fingerbreadth inf to zygomatic arch , supplies parotid gland, masseter and skin of face, anastomoses with branches of facial a.

Venous drainage

  • facial vein is major route of drainage from face
  • formed by union of supraorbital and supratrochlear vv. at med angle of eye
  • connected sup ophthalmic v. through supraorbital v. (near zygomatic process)
  • connected to cavernous sinus by ophthalmic v.
  • crosses superf to submandibular gland and is joined by anterior division of retromandibular v. to form common facial v., which ends by draining into internal jugular v.

Retromandibular Vein

  • formed by union of superf temporal and maxillary vv., post to neck of mandible
  • descends within parotid gland, superf to ext carotid a. but deep to facial n.
  • divides into ant branch that unites with facial v. and post branch that joins posterior auricular v. to form external jugular v.

Lymph drainage

  • forehead and ant face ® submandibular nodes
  • lat face ® parotid nodes
  • central lower lip and chin ® submental nodes

Muscles of face

  • embedded in superficial fascia
  • most arise from bones of face and insert into skin, they don’t move bony structures
  • orbit, nose and mouth are guarded by eyelids, nostrils and lips respectively
  • facial muscles serve as sphincter, or dilators of the facial openings
  • all develop from 2nd pharyngeal arch and are supplied by facial n. (VII cranial)
Eye

orbicularis oculi

sphincter (narrows eye and encourages secretion of tears)

three parts: orbital (closing eyes tightly), palpebral (closing eyes lightly), lacrimal (pulls eye med)

Nose

nasalis

compression/dilation of nostril

compressor naris: rudimentary in human

dilators of nose: flare the alar cartilages of nose

Mouth

orbicularis oris

sphincter

fibres derived from buccinator and or facial muscles

dilator muscles

 

radiate out like spokes

buccinator

presses cheeks against teeth

attached to alveolar processes and pterygomandibular raphe fibres mingle with orbicularis oris

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Scalp


Covers vault of skull and extends sideways between right and left temporal lines, between eyebrows anteriorly and sup nuchal lines posteriorly.

    Scalp
Boundaries  

covers vault of skull

lat: temporal lines

ant: eyebrows

post: sup nuchal line

Contents Arteries

from int carotid (supraorbital, supratrochlear)

from ext carotid (superf temporal, post auricular occipital)

Veins

supratrochlear & supraorbital (® facial)

superf temporal + maxillary (® retromandibular)

post auricular + post retromandibular (® ext jugular)

occipital (® suboccipital plexus ® vertebral)

emissary (communication with inside of skull)

Nerves

trigeminal (supratrocheal, supraorbital, zygomatico-temporal, auriculo-temporal)

C2 (greater & lesser occipital)

Muscles

occipitofrontalis

tempoparietalis

Lymph

scalp above parotid gland ® parotid lymph nodes

scalp above auricle ® retroauricular lymph nodes

back of scalp ® occipital lymph nodes

Notes  

trigeminal supply ant to line between ears and vertex, C2 supplies rest

Layers

  • has five layers, of which first three are intimately bound toger: skin, connective tissue, aponeurosis epicranialis (scalp proper), loose areolar tissue, and pericranium
  • mobile because of potential cleavage plane

Epicranial Aponeurosis

  • strong membranous sheet that covers sup aspect of calvaria
  • aponeurosis is membranous tendon of fleshly bellies of epicranial muscle (formed by occipitalis and frontalis muscles, each with two bellies: 2 frontal & 2 occipital)

muscles are supplied by facial nerve (VII)

Applied Anatomy

  • scalp richly supplied by blood ® small lacerations may bleed profusely
  • tension of epicranial aponeurosis (produced by occipitofrontalis) means that deep wounds dividing aponeurosis will gape
  • infection of scalp may occasionally spread (via emissary vv.) to skull bones, infected blood in diploic vv. may travel via emissary vv. into venous sinuses and produced venous sinus thrombosis
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Cranial Fossae


  • cranial base has three levels called anterior, middle and posterior cranial fossae
  • each fossa slightly inferior to one rostral to it

Anterior Cranial Fossa

  • occupied by of frontal lobes of cerebral hemispheres
  • formed mainly by frontal bone (ant boundary)
  • most floor composed of convex orbital parts (bone roof of orbits)
  • shows sinuous, shallow depression called convolution impressions or brain markings, possibly formed by the gyri of the brain
  • crista galli is median process (resembling cock’s crest) that projects sup from ethmoid bone
  • on both sides of crista galli is a narrow, cribriform plate, with numerous foramina for olfactory nn.
  • lesser wings and jugum of sphenoid bone form posterior floor (boundary) of fossa
  • lesser wings have sharp post spenoidal ridges that overhang ant middle fossa and project into ant part of lateral sulci
  • each lesser wing ends med in ant clinoid process which gives attachment to tentorium cerebelli

Middle Cranial Fossa

  • occupied by temporal poles and ~½ of inf surface of temporal lobe
  • marked off from posterior fossa by dorsum sellae (med) and sup border of petrous part of temporal bone (lat), and from ant fossa by posterior edge of lesser wing of sphenoid
  • saddle-like part of spenoid bone (between ant & post clinoid processes) known as sella turcica, composed of three parts:
  • tuberculum sellae: ant, olive-shaped swelling
  • hypophoseal fossa: mid, seat-like depression
  • dorsum sellae: post, median rectangular projection

Posterior Cranial Fossa

  • largest and deepest of fossae
  • occupied by pons, cerebellum and medulla
  • formed largely by inf and ant occipital bone, but sphenoid and temporal bones also contribute
  • broad bony grooves formed by transverse sinuses lie between diverging folds of tentorium cerebelli (groove for right usually larger because sup sagittal sinus usually enter on right)
  • foramen magnum
    located in centre of fossa
  • rostral to foramen, basilar part of occipital bone rises to meet sphenoid bone, called clivus
  • internal occipital crests
    is bony crest that lies post and sup to foramen magnum
  • partly divides post cranial fossa into two cerebellar fossae that lodge cerebellar hemispheres
  • end sup and post inirregular elevation called internal occipital protuberance
  • vermis of cerebellum lies in vermian fossa, just post to foramen magnum

Foramina of the Skull

  Foramina Contents
  Or Nerves
Anterior

foramen cecum

nasal emissary v. (present in children and 1% of adults)

 

foramina in cribiform plates

 

axons of olfactory cells

ant & post ethmoidal foramina

vessels and nn. with same names

 
Middle

optic canals

ophthalmic aa.

CN II

sup orbital fissures*

ophthalmic vv.

CN V1, III, IV, VI, SNS

foramen rotundum*

 

CV V2 (maxillary n.)

foramen ovale*

accessory meningeal a.

CN V3 (mandibular n.)

foramen spinosum*

mid meningeal vessels

meningeal branch of CN V3

foramen lacerum*

int carotid a.

accompanying sympathetic and venous plexuses

 

hiatus of greater petrosal n.

petrosal branch of mid meningeal a

greater petrosal n.

Posterior

foramen magnum

vertebral, ant & post spinal aa.

dural vv.

medulla and meninges

spinal roots of CN XI

jugular foramen

sup bulb of int jugular v., inf petrosal & sigmoid sinuses

meningeal branches of asc pharyngeal and occipital aa.

CN IX, X, XI

hypoglossal canal

 

CN XII

condylar canal

emissary v.

 

mastoid foramen

mastoid emissary v.

meningeal branch of occipital a.

 

* part of crescent of foramina

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Cranial Meninges and CSF


  • brain is enveloped by three membranes: dura mater, arachnoid mater and pia mater (arachnoid + pia = leptomeninges), collectively known as cranial meninges
  • continuous with spinal meninges covering spinal cord
  • cranial meninges and CSF provide support and protection for brain

Dura Mater

  • outermost and toughest of cranial meninges
  • consists of collagenous connective tissue
  • dura mater loosely attached to calvaria, but tightly attached to base
  • fractures of base more easily damage dura leading to leakage of CSF out of nose and ear
  • two layered structure
  • inner: meningeal
  • outer: endosteal
  • internal layer continuous with spinal dura at foramen magnum
  • provides tubular sheaths for CNS as they pass through foramina in floors of cranial fossae; outside skull theyy fuse with epineurium, dural sheaths of cranial nerves extend approximately to cranial ganglia
  • trigeminal ganglion surround by extension of cranial meninges, occupies trigeminal cave in trigeminal impression in petrous part of temporal bone
  • dural sheath of optic nerve continuous with int meningeal layer of cranial dura and sclera of eye

Dural Septa or Reflections

  • during development of brain, dura duplicated to form four inwardly projecting dural septa
  • septa divide cranial cavity into three intercommunicating compartments, one subtentorial and two supratentorial

Falx Cerebri

  • large, sickle shaped vertical partition in longitudinal fissure between hemispheres
  • attached in median place to int surface of calvaria from frontal crest of frontal bone and crista galli of ethmoid bone ant, and int occipital protuberance post
  • also attached to midline of tentorium cerebelli
  • at sup border, its two layers separate to enclose sup sagittal sinus, free inf edge encloses inf sagittal sinus
  • forms rigid partition between hemispheres and reduces side-to-side movement

Tentorium Cerebelli

  • wide tent-shaped, arched fold of dura
  • separates occipital lobes from cerebellum
  • med attachment of falx cerebri holds tentorium cerebelli up
  • attached ant-lat to sup petromastoid parts of temporal bones and ant & post clinoid processes
  • attached post to occipital bone along grooves for transverse sinuses, which it encloses
  • U-shaped ant border is free, between it and dorsum sellae is opening called tentorial notch, which surrounds midbrain

Falx Cerebelli

  • small, sickle-shaped median dural fold in post post cranial fossa
  • extends almost vertically, inf to inf tentorium cerebelli
  • free-edge projected slightly between cerebellar hemispheres
  • occipital sinuses contained in fixed edge

Diaphragma Sellae

  • small, circular, horizontal sheet of dura formsroof for hypophyseal fossa
  • formed by dura surrounding pituitary gland and encircling its stalk

Arteries

  • many meningeal aa. in periosteum supply most blood to periosteum, not meninges!
  • only very fine branches of are distributed to dura
  • middle meningeal a. is largest of meningeal aa., branch of maxillary a., embedded in dura, clinically imp because it can be torn when skull is fractured
  • enters cranial cavity through foramen spinosum, runs lat along floor of the middle cranial fossa, turns sup-ant on greater wing of sphenoid, where it divides into ant and post branches
  • ant branch
  • runs sup to pterion and curves post to ascend towards vertex of skull, often found inbony tunnel in region of pterion post branch
    runs post in groove in squamous part of temporal bone, n ramifies all over post skull
  • all meningeal aa. accompanied by veins, lie between aa. and bones

Nerve Supply

  • rich sensory supply largely through three divisions of trigeminal n.

Arachnoid Mater

  • delicate, transparent membrane, composed of weblike tissue
  • forms intermediate covering of brain and separated from dura by film of fluid in potential subdural space
  • it does not closely investment of brain, but passes over sulci and fissures
  • separated from pia by subarachnoid space
  • numerous trabeculae pass from arachnoid to pia, givingweblike structure

Pia Mater

  • very thin, highly vascularised, loose connective issue membrane that adheres closely to surface of brain
  • dips into all sulci and fissures and carries blood vessels with it
  • cerebral veins run on pia within subarachnoid space
  • when branches of cerebral vessels penetrate brain, pia follows for a short distance, forming sleeve of pia, refore perivascular spaces are continuous with subarachnoid space

Venous Sinuses of Dura Mater

  • sinuses are venous channels located between dura and int endosteal lining of cranium
  • drain all blood from brain

Superior Sagittal Sinus

  • lies in superior border of falx cerebri
  • usually ends by becoming right transverse sinus
  • dilation at termination known as confluence of sinuses as five sinuses communicate with it

Inferior Sagittal Sinus

  • lies in inf border of falx cerebri
  • much smaller than sup sagittal sinus
  • ends by joining great cerebral v. to form straight sinus

Straight Sinus

  • runs along the line of attachment of falx cerebri to tentorium cerebelli
  • ends by joining one of transverse sinuses, usually left

Transverse Sinus

  • pass lat from confluence of sinuses in attached border of tentorium cerebelli
  • leave tentorium and become sigmoid sinuses

Sigmoid Sinuses

  • follow S-shaped course in post cranial fossa, forming deep groove in the temporal and occipital bones, turn ant and enter sup bulbs of int jugular vv.

Occipital Sinus

  • lies in attached edge of falx cerebelli

Superior and iferior Petrosal Sinuses

  • they drain the cavernous sinus into the transversesinus and int j v respectively

Cavernous Sinuses

  • large venous sinuses, 2 cm x 1 cm, capacity: 1.5 ml
  • located on eir side of pituitary in sella turcica
  • runs from apex of orbit to apex of petrous temporal bone
  • contain many blood channels formed by numerous trabeculae

Receives blood from:

  • sup and inf ophthalmic vv. (orbit)
  • superf mid cerebral v. (brain)
  • sphenoparietal sinus (skull)
  • intercavernous sinuses (cavernous sinus of or side)

Drains blood into

  • sup and inf petrosal sinuses
  • pterygoid venous plexus

Relations

  • ant: apex of orbit
  • post: brain stem (junction of peduncle with pons)
  • med: body of sphenoid bone and pituitary fossa
  • lat: temporal lobe
  • sup: int carotid a., uncus of temporal lobe
  • inf: greater wing of sphenoid

Immediate relations

  • lat: oculomotor, trochlear, ophthalmic, and maxillary nn.
  • inside sinus but outside blood: int carotid a., abducens n.
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Mouth


  • oral cavity is divided into vestibule and mouth proper
  • vestibule lies within cheek and lips, but outside gums and teeth
  • mouth cavity communicates post with pharynx through oropharyngeal isthmus (isthmus of fauces)
  • bounded by soft palate above, tongue below and palatoglossal arches on each side
  • palate (hard and soft) forms roof of mouth

Lips

  • covered ext by skin, int by mucous membrane
  • contains part of orbicularis oris
  • attach to gum by frenulum
  • mucous labial glands moisten lip
  • meet at angles (labial commisures) of mouth

Cheeks

  • directly continuous with lips and have same general structure
  • buccinator forms muscle layer
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Tongue


General Features

  • three parts: root (or base, post 1/3, post-sulcal, pharyngeal part); body (or ant 2/3, pre-sulcal, oral part); and tip
  • two surfaces: upper (dorsum) and lower (ventrum)
  • upper surface divided into two parts by V shaped sulcus terminalis: ant 2/3 oral part, post 1/3 pharyngeal part
  • foramen caecum
  • located at apex of V mucous membrane of the upper surface of the oral part is rough due to presence of numerous lingual papillae
  • mucous membrane of the lower surface of the oral part is smooth , devoid of papillae, and shows visible deep lingual v. either side of frenulum
  • post 1/3 is devoid of papillae but has a nodular irregular surface caused by the underlying lymph nodules called lingual tonsil.
  • the interval between the post 1/3of the tongue and the epiglottis is part of oropharynx and shows: median and lateral glossoeppiglottic folds, and vallecullae (a small depression detween the two folds)

Lingual Muscularture

Muscles Main action Nerve supply
Extrinsic

genioglossus

protrusion

 

CN XII

hyoglossus

depression

styloglossus

retraction

palatoglossus

elevation

Pharyngeal plexus

Intrinsic

sup longitudinal muscle

 

they change the shape of the tongue

 

CN XII

inf longitudinal muscle

transverse muscle

vertical muscle

Nerve Supply

  Ant Post
Sensory General lingual (CN V) glossopharyngeal
Special chorda tympani (CN VII)
Motor   hypoglossal (except for palatoglossus, supplied by CN X)

Arterial Supply

  • major: lingual a.
  • also tonsillar and asc palatine branches of facial a.

Venous Drainage

  • all veins on one side unite to form lingual v., which drains into int jugular or facial v.

Lymphatics

  • tip: submental
  • ant 2/3: submandibular (central cross to opposite side as well)
  • post 1/3: deep cervical

Applied Anatomy

  • glossitis usually accompanies stomatitis
  • in acute glossitis, oedema and swelling of tongue are marked (facilitated by loose c.t. and plenty of lymphatics)
  • in some anaemias and vitamin deficiencies tongue becomes bald, due to atrophy of filiform papillae
  • lesion of hypoglossal n. results in paralysis of affected side and hemiatrophy, when patient tries to stick out tongue, deviates to paralysed side
  • in unconscious patient, post tongue may fall back and cause laryngeal obstruction
  • carcinoma of post tongue has poor prognosis due to bilateral lymphatic spread
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Palate


Hard Palate

  • skeleton: palatine process of maxilla, horizontal plate of palatine
  • alveolar margin: teeth and gums
  • post margin: soft palate
  • oral surface: stratified squamous keratinised epith, mucosa adheres to bone, palatine raphe, transverse palatine folds, mucosal glands prominent

Soft Palate

  • base: attached to post hard palate
  • free post border presents uvula in midline
  • palatoglossal folds
    extend inf and ant; and palatopharyngeal folds extend inf and post from the under surface of the soft palate
  • has oral (lower) and pharyngeal (upper) surfaces

Structure

  • oral mucosa on oral surface and adjoining pharyngeal surface; rest covered by respiratory mucosa
  • core is palatine aponeurosis with levator palati on upper surface and palatopharyngeus and palatoglossus on lower surface

Muscles

  • tensor and levator palati
  • musculus uvulae
  • palatoglossus
  • palatopharyngeus

Blood Supply

  • branches of maxillary a. (greater and lesser palatine aa.)
  • veins drain into pterygoid venous plexus

Lymphatics

  • drain into submandibular, retropharyngeal, and deep cervical nodes

Nerve Supply

  • sensory: greater and lesser palatine nn., nasopalatine n.
  • motor: pharyngeal plexus, except tensor palati supplied by mandibular n.
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Submandibular region


  • lies between body of mandible and hyoid bone
  • superficial part includes submental and digastric triangles
  • deeper parts include root of tongue and floor of mouth

Structures

  • muscles: digastric, stylohyoid, mylohyoid, hyoglossus
  • submandibular gland
  • mixture of serous and mucous acini
  • two parts: superficial and deep
  • superficial: in digastric triangle, reaching upward under cover of mandible, separated post from parotid gland by stylomandibular lig
  • deep: extends forwards in interval between mylohyoid and hyoglossus, post end continuous with superf part of gland, while ant end reaches as far as sublingual gland
  • coverings: inner ct capsule and outer fibrous capsule (derived from deep cervical fascia)
  • submandibular duct: runs from ant deep submandibular gland, forward between mylohyoid and hyglossus
  • blood supply: branches of lingual and facial, veins follow aa.
  • nerve supply: derived from submandibular ganglion (receives parasympathetic fibres from chorda tympani, lingual and sympathetic trunk)
  • applied submandibular salivary gland
  • common site of calculus formation
  • presence of tense swelling below body of mandible, greatest before and during meal and reduced in size or absent between meals
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Parotid Glands


  • largest of salivary glands (branched serous acini)
  • very irregular shape because it’s wedged in among number of structures
  • covered by a capsule and a dense fibrous tissue sheath (parotid fascia) formed by deep cervical fascia
  • divided into two (superficial and deep) parts by facial n.:

Position and Extent

  • lies in fossa post to ramus of mandible
  • extends from external acoustic meatus to upper part of carotid triangle
  • med, extends to styloid process and around neck of mandible
  • post, overlaps sternocleidomastoid and extends ant over masseter
  • portion of facial part often detached and called accessory parotid gland
  • wedge-shaped (base above, apex behind angle of mandible)
  • sup: extends upward behind TM joint into post mandibular fossa, called glenoid process
  • ant: extends forwards superf to masseter, called facial process

Parotid Duct

  • 5 cm long, 5mm wide
  • passes horizontally from ant edge, turns med at ant masseter and pierces buccinator, and enters oral cavity opposite crown of 2nd maxillary molar tooth

Structures within the Gland

  • facial n (superf)
  • retromandibular v
  • external carotid a. (deep)

Nerve and blood Supply

  • supplied by branches of external carotid a., drains by tributaries of retromandibular v.
  • secretomotor (parasympathetic): from glossopharyngeal n. (IX), via otic ganglion
  • sensory: branches from greater auricular and auriculo-temporal nn.
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Nose and Nasal Cavity


  • sup part of respiratory tract and contains peripheral organ of smell
  • divided into right and left nasal cavities by nasal septum
  • its mucosa is divisible into olfactory and respiratory areas
  • functions include
    respiration
    olfaction
    filtration of dust
    humidification of inspired
    receives secretion form paranasal sinuses and nasolacrimal ducts

Skeleton of External Nose

  • immovable bridge of nose (sup bony part of nose) consists of nasal bones, frontal processes of maxillae and nasal part of frontal bone

Nasal Septum

  • bony part of septum usually located in med plane, until 7 years of age when it deviates slightly to one side (more frequently right)
  • nasal septum has three main components
  • perpendicular plate of ethmoid bone: (forms sup part, very thin, desc from cribriform plate)
  • vomer: (forms post-inf part, thin, flat bone)
  • septal cartilage
  • movable cartilaginous part of nose consits of five main cartilages andfew smaller ones
  • composed of hyaline cartilage
  • connected with one anor and nasal bones by continuity of perichondrium and periosteum
  • U-shaped alar nasal cartilages are free and movable, can dilate and constrict nares

Nasal Cavities

  • nasal cavity opens anteriorly through nostrils or ant nares
  • open posteriorly into nasopharynx through choanae (post nasal aperture)
  • mucosa lines entire nasal cavity, except vestibule
  • entrance to vestibule of nose is lined with skin containing hairs called vibrissae
  • nasal mucosa is tightly bound to periosteum and perichondrium of supporting structures
  • continuous with lining of all chambers with which nasal cavities communicate
  • inf 2/3 called respiratory area, and sup 1/3 called olfactory area

Walls

  • floor: palatine process of maxilla, horizontal plate of palatine bone
  • roof: nasal bone, frontal bone, cribriform plate of ethmoidal bone and body of sphenoidal bone, communication with cranial cavity through cribriform plate
  • septum: formed by vomer, perpendicular plate of ethmoid, septal cartilage, fibrofatty tissue of mobile septum
  • lateral wall: skeletal framework : nasal bone; frontal process of maxilla, lacrimal,; ethmoid labyrinth with sup and mid conchae, inf concha, perpendicular plate of palatine bone, med pterygoid plate
  • uneven due to three shelf-like projections called superior, middle and inferior conchae
  • sphenoethmoidal recess lies above sup concha; other spaces are sup, middle and inf meatuses lie below the corresponding conchae
  • hiatus semilunaris is a curved cleft (window) in the middle meatus, lies between bulla ethmoidalis superiorly and uncinate process of ethmoid bone inferiorly
  • infundibulum: is a space within the middle meatus that lies lat to the hiatus it receives the frontonasal duct (draining the frontal and ant ethmoid sinuses)
  • maxillary sinus opens in the middle meatus, below the bulla and above the inferior edge of the hiatus
  • post ethmoidal sinus opens in sup meatus; nasolacrimal ducts into inf meatus
  • sphenoidal sinus opens in sphenoethmoidal recess

Linings

  • vestibule: lined by skin with vibrissae
  • roof, adjoining septum and alt wall – olfactory mucosa
  • rest of nasal cavity – respiratory mucosa
  • nasal mucosa continuous with that in paranasal air sinuses

Nerve Supply

  • CN I: olfactory area in the upper part of nasal cavity
  • CN V1: ethmoidal branches of nasocilliary n
  • CN V2: branches to the walls of the nasal cavity

Arterial Supply

  • derived mainly from branches of:
  • maxillary a.(sphenopalatine, greater palatine)
  • ophthalmic a. (ethmoidal a.)
  • facial a. (sup labial, ascendimg palatine, lateral nasal)

Venous drainage

  • rich venous plexuses in the nasal mucosa are drained by pterygoid plexus, facial v and ophthalmic veins

Lymphatics

  • drain into submandibular, retropharyngeal, and upper deep cervical nodes
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Paranasal Air Sinuses


  • definition: they are air filled cavities within the frontal, ethmoidal, sphenoidal and maxillary bones, are lined with the respiratory epithelium, and communicate with the nasal cavity through small apertures
  • rudimentary at birth; grow at 6-7 years to attain maximum size at puberty; in adult, they vary considerably in size in different people

Mucosa

  • respiratory type, but thin, less vascular and loosely attached to periosteum

Frontal Sinus

  • situated between inner and outer tables of frontal bones beneath med 1/3 of superciliary arch
  • opens into mid meatus via infundibulum

Maxillary Sinus

  • is the largest of paranasal sinuses; situated in maxilla
  • pyramidal in shape, apex facing zygoma, and base towards the nasal cavity
  • opens in mid meatus, well above its floor

Ethmoidal Sinuses

  • numerous cavities called cells, within ethmoidal labyrinth
  • are grouped into ant, mid and post groups
  • all contained in labyrinthine (lateral) part of ethmoidal bone
  • ant ethmoid sinus opens with frontal sinus in the middle meatus via infundibulum
  • mid ethmoid sinus underlies bulla ethmoidalis; opens on the bulla into the middle meatus
  • post ethmoid opens into sup meatus

Sphenoidal Sinus

  • situated in body of sphenoid bone; divided by a septum
  • related to the pituitary gland, cavernous sinus, and internal carotid a.
  • opens into sphenoethmoidal recess

Nerve Supply of Paranasal Sinuses

  • branches of CN V1
  • branches of CN V2

Blood Supply of Paranasal Sinuses

  • branches of maxillary a.
  • branches of ophthalmic a.
  • branches of facial artery.

Lymphatics of Paranasal Sinuses

  • submandibular group (frontal, ant and middle ethmoidal and maxillary sinuses)
  • retropharyngeal group (post ethmoidal and sphenoidal sinuses)
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Orbit and contents


  • bones that form orbit are lined with periosteum, called periorbita or orbital periosteum
  • at optic canal and sup orbital fissure, periorbita becomes continuous with periosteum lining interior of skull
  • also continuous over orbital margins and through inf orbital fissure with periosteum covering external surface of skull
  • forms funnel-shaped fascial sheath that encloses orbital contents
  • may be easily detached especially from roof and med wall

Margins of the orbit

  • med: frontal and maxillary
  • sup: frontal
  • lat: zygomatic and frontal
  • inf: zygomatic and maxillary

Walls of the orbit

  • med: maxilla, lacrimal, ethmoid, sphenoid. Features: nasolacrimal canal, ant & post
  • ethmoidal foramen
  • sup(roof): frontal (orbital plate), sphenoid (lesser wing). Features: lacrimal fossa, optic
  • foramen, trochlear fossa
  • lat: sphenoid (greater wing), zygomatic (orbital surface). Feature: zygomatic
  • canal
  • inf (floor): maxilla, zygomatic, palatine. Features: infraorbital canal and groove

Superior Orbital Fissure

  • separates lat wall from sup wall (roof)
  • lies between lesser and greater wings of sphenoid
  • connects orbit with mid cranial foss
  • transmits CN III, IV, V1, ophthalmic vv.

Inferior Orbital Fissure

  • separates floor from lat wall
  • lies between greater wing, maxilla and zygomatic bone
  • connects orbits with pterygolpalatine and infratemporal fossae
  • transmits maxillary n., zygomatic n., infraorbital vessels

Contents (Muscles)

Muscle Origin Insertion Innervation Action

Levator palpebrae superioris

roof of orbit, ant to optic canal

skin of upper eyelid

CN III

 

 

elevates upper lid

Superior rectus

common tendinous ring

just post to sclerocorneal junction

elevate, adduct

Inferior rectus

depress, adduct

Medial rectus

adducts eye

Lateral rectus

CN VI

abducts eye

Superior oblique

body of sphenoid

runs through trochlea, post-sup lat orbit

CN IV

depress, abduct

Inferior oblique

maxilla in floor of orbit

post-inf lat orbit

CN III

elevate, abduct

Fascial Sheath of eyeball (bulbar fascia or Tenon’s fascia):

  • thin cuplike sheath surrounds eyeball, except for corneal part
  • separates it from fat and or contents in orbit
  • attached posteriorly to sclera close to optic nerve and anteriorly just post to cornea
  • tendon of muscles pierce sheath on their way to their attachments
  • blends with fascial sheaths of ocular muscles
  • fuses with dural sheath of optic nerve
  • potential space between eyeball and fascial sheath allows eyeball to move freely
  • triangular expansions (called check ligaments) from sheaths of med and lat rectus muscles are attached to lacrimal and zygomatic bones respectively
  • thickening of inf part of the fascial sheath of eye called suspensory ligament of eyeball
  • suspen lig is attached to ant parts of medal and lateral walls of orbit
  • suspen lig supports eyeball with its hammock-like shape

Nerves of Orbit

  • CN II, III, IV, V1, VI
  • ciliary ganglion

Blood Vessels

  • orbital contents supplied by ophthalmic a.
  • infraorbital a. also contributes some blood to this region
  • venous drainage is through ophthalmic vv., sup & inf

Ophthalmic Artery

  • arise from int carotid a. as it emerges from cavernous sinus
  • pass through optic foramen within dural sheath of optic nerve and runs ant close to sup-med wall of orbit
  • gives off branches to structures in orbit and to ethmoid bone

Central Artery of Retina

  • one of smallest but most important branches of ophthalmic a.
  • arises inf to optic n.
  • runs within dural sheath of optic nerve until it approaches eyeball, n pierces optic nerve and runs within it to emerge through optic disc, spreads over int surface of retina
  • twigs of artery anastomose with ciliary a. but terminal branches are essentially end aa.

Ciliary Arteries

  • ciliary aa
  • supply sclera, choroid, ciliary body and iris two long post ciliary aa. piece sclera and supply ciliary body and iris
  • several short post ciliary aa. pierce sclera and supply choroids
  • ant ciliary aa are branches from muscular arteries. They supply conjunctiva and iris

Lacrimal Artery

  • supplies lacrimal gland, conjunctiva and eyelids
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Temporal region


Temporal Fossa

  • oval in shape on the lat aspect of the skull
  • bounded sup and post by temporal lines
  • inf, it communicates with infratemporal fossa
  • roofed by temporal fascia
  • occupied by temporalis muscle

Infratemporal Fossa

  • irregularly-shaped space inf and deep to zygomatic arch and post to maxilla
  • communicates with temporal fossa through interval between arch and skull and temporal msucles and deep temporal nerves and vessels pass through it

Boundaries

  • ant: post surface of maxilla
  • post: styloid process
  • sup: infratemporal surface of greater wing of sphenoid
  • inf: continuous with submandibular region
  • lat: ramus of mandibular
  • med: lat pterygoid plate

Contents

  • muscles: lat and med pterygoid, lower part of temporalis
  • nerves: mandibular, otic ganglion, chorda tympani
  • vessels: maxillary a. and v, pterygoid venous plexus

Maxillary a.

  • larger of two terminal branches of ext carotid
  • arises post to neck of mandible, passes forwards (deep to neck), and transverses infratemporal fossa, passes superf to lat pterygoid and then disappears into pterygopalatine fossa
Part (divided by lat pterygoid) Course Branches
First

passes horizontally forwards between neck of mandible and lower border of pterygoid

deep auricular

ant tympanic

mid meningeal

accessory meningeal

inf alveolar

Second

runs obliquely forward and upwards superf to inf head of lat pterygoid

to muscles of this region

Third

runs between sup and inf heads of lat pterygoid, then through pteryggomaxillary fissure into pterygomandibular fossa

post sup alveolar

infraorbital

desc. palantine

pharyngeal

sphenopalatine

Pterygoid Venous Plexus

  • is associated with pterygoid muscles
  • connected to facial v. through deep facial vv.
  • connected to cavernous sinus through vv. passing through foramen ovale and lacerum

Mandibular Nerve

  • branches into all nerves in infratemporal region (except for chorda tympani, branch of facial)
  • descends through foramen ovale into infratemporal fossa, divides into sensory and motor fibres
  • supply four muscles of mastication, but not buccinator
Part Type Branch Notes

Main trunk

Motor (3)

med pterygoid m

 

tensor tympani m

 

tensor palati m

 

Sensory (1)

meningeal

 

Ant division

Motor (3)

massteric n to masseter m

 

deep temporal nn. to temporalis

 

n. to lat pterygoid

 

Sensory (1)

buccal

usually runs between two heads of lat pterygoid, desc through deep temporalis, supplies skin and mucous membrane of cheek

Post division

Motor (1)

n. to mylohyoid and ant digastric

 

Sensory (3)

auriculotemporal

encircles med meningeal a., breaks up into many branches, largest passes post, med to neck of mandible and supplies auricle and temporal region, also sends articular fibres to temperomandibular joint

lingual

lies ant to inf alveolar n., sensory to tongue, floor of mouth and gingivae, enters mouth between med pterygoid muscle and ramus of mandible, passes ant under oral mucosa, just inf to 3rd molar tooth

chorda tympani branch of facial n. travels with it

inf alveolar

enters mandibular foramen, passes through mandibular canal (where it sends nn. to teeth) and appears on face as mental n., supplies skin and mucous membrane of lower lip, skin of chin

Otic Ganglion

  • is parasympathetic ganglion
  • is located in infratemporal fossa, just inf to foramen ovale, med to mandibular n. and post to med pterygoid muscle
  • secretory to parotid gland

Temporomandibular Joint

  • type: synovial joint; subtype: modified hinge or condylar variety
  • articular surface involved are:
  • head or condyle of mandible (inf)
  • articular tubercle and mandibular fossa of squamous temporal bone (sup)
  • articular disk
    separates joint cavity into sup and inf compartments
  • fused with articular capsule surround joint and is bound sup to limits of temporal articular surface int to neck of mandible
  • articular disc is more firmly attached to mandible than to the temporal bone
  • loose articular capsule attached to margins of area on temporal bone and neck of mandible
  • thickened lat to form lat (temporomandibular) ligament
  • base attached to zygomatic process, apex to lat side of neck of mandible
  • stylomandibular and sphenomandibular also help to support the T-M joint
Movement Muscles

depression

hyoid muscles, gravity

elevation

temporalis, masseter, med pterygoid

protrusion

lat and med pterygoid, masseter (deep fibres)

retraction

post temporalis

side-to-side

med and lat pterygoid, masseter

Muscle Origin Insertion

Temporalis

temporal fascia

coronoid process, ant ramus

Masseter

zygomatic arch

lat ramus

Lat pterygoid

sup: infratemporal crest

inf: lat lat pterygoid plate

neck of mandible, articular disk

Med pterygoid

superf: maxillary tuberosity

deep: med lat pterygoid plate

med ramus

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