Anatomy Summary
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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)
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Ethmoid bone (single)
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Sphenoid bone (single)
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Occipital bone (single)
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Parietal bone (paired)
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Temporal bone (paired)
The 14 Bones of facial skeleton (2single and 6 paired) •
Vomer (single)
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Nasal bone (paired)
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Lacrimal bone (paired)
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Inferior concha (paired)
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Palatine bone (paired)
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Zygomatic bone (paired)
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Maxilla (paired)
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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)
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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
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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
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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.
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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 •
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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)
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Anterior Aspect o
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can be divided into five areas: frontal, orbital, maxillary, nasal and mandibular 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 e xt 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 o
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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
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two parietal bones joined by sagittal suture
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frontal and parietal bones joined by coronal suture
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parietal and occipital bones joined by lambdoid sutures
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intersection of coronal and sagittal sutures is called bregma
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vertex, most sup part of skull, located near centre of sagittal suture
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notable features are forehead, orbits, prominence of cheek, anterior nasal apertures, paired maxillae, and mandible
Posterior Aspect o
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comprises ant part of calvaria superiorly and skeleton of face inferiorly
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 o
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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
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Lateral Aspect o
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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 o
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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
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sutures least distinct on inside because fusion begins ~10 years earlier
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arachnoid granulations
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includes parietal, frontal and parts of temporal and sphenoid bones
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 o
thinner in females, young and old
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tends to be thinnest in areas that are well covered by muscles
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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
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cranium is essentially one big complex bone
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Frontal Bone o
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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
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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
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this isdepression in root of nose, where it joins cranium
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also articulates with zygomatic, lacrimal, ethmoid and sphenoid bones
Parietal Bones o
form large parts of wall of calvaria Top
Face •
face extends from margin of hair to chin, from one auricle to or
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forehead common to both face and scalp
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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
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wholly sensory and supplies skin derived from frontonasal prominence
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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.
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supplies root of nose through infratrochlear n.
Frontal •
direct continuation of V1
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divides into two branches: supraorbital (med) and supratrochlear (lat)
Lacrimal
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smallest of main ophthalmic branches
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emerges over sup-lat orbital margin to supply the lat part of upper eyelid
Maxillary Nerve (V2) •
intermediate division of trigeminal nerve
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three cutaneous branches supply skin derived from maxillary prominence
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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) •
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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 •
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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.
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branches from supraorbital and supratrochlear supply skin of forehead
Facial Artery
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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 •
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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
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formed by union of supraorbital and supratrochlear vv. at med angle of eye
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connected sup ophthalmic v. through supraorbital v. (near zygomatic process)
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connected to cavernous sinus by ophthalmic v.
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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
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descends within parotid gland, superf to ext carotid a. but deep to facial n.
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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
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lat face ® parotid nodes
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central lower lip and chin ® submental nodes
Muscles of face •
embedded in superficial fascia
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most arise from bones of face and insert into skin, they don’t move bony structures
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orbit, nose and mouth are guarded by eyelids, nostrils and lips respectively
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facial muscles serve as sphincter, or dilators of the facial openings
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all develop from 2nd pharyngeal arch and are supplied by facial n. (VII cranial)
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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 buccinator
radiate out like spokes presses cheeks against teeth
attached to alveolar processes and pterygomandibular raphe fibres mingle with orbicularis oris Top
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)
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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 •
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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 •
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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 •
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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 Top
Cranial Fossae •
cranial base has three levels called anterior, middle and posterior cranial fossae
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each fossa slightly inferior to one rostral to it
Anterior Cranial Fossa •
occupied by of frontal lobes of cerebral hemispheres
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formed mainly by frontal bone (ant boundary)
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most floor composed of convex orbital parts (bone roof of orbits)
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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 •
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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:
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tuberculum sellae: ant, olive-shaped swelling
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hypophoseal fossa: mid, seat-like depression
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dorsum sellae: post, median rectangular projection
Posterior Cranial Fossa •
largest and deepest of fossae
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occupied by pons, cerebellum and medulla
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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
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end sup and post inirregular elevation called internal occipital protuberance
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vermis of cerebellum lies in vermian fossa, just post to foramen magnum
Foramina of the Skull
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Foramina Anterior foramen cecum
Contents Or nasal emissary v. (present in children and 1% of adults)
foramina in cribiform plates
Middle
Nerves
axons of olfactory cells
ant & post ethmoidal foramina
vessels and nn. with same names
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
int carotid a. foramen lacerum*
accompanying sympathetic and venous plexuses
hiatus of greater petrosal n.
Posterior
petrosal branch of mid meningeal greater petrosal n. a vertebral, ant & post spinal aa.
medulla and meninges
dural vv.
spinal roots of CN XI
sup bulb of int jugular v., inf
CN IX, X, XI
foramen magnum
petrosal & sigmoid sinuses jugular foramen meningeal branches of asc pharyngeal and occipital aa. hypoglossal canal
CN XII
condylar canal
emissary v.
mastoid foramen
mastoid emissary v.
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meningeal branch of occipital a.
* part of crescent of foramina
Top
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
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continuous with spinal meninges covering spinal cord
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cranial meninges and CSF provide support and protection for brain
Dura Mater •
outermost and toughest of cranial meninges
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consists of collagenous connective tissue
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dura mater loosely attached to calvaria, but tightly attached to base
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fractures of base more easily damage dura leading to leakage of CSF out of nose and ear
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two layered structure
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inner: meningeal
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outer: endosteal
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internal layer continuous with spinal dura at foramen magnum
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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 •
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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 •
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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
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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
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separates occipital lobes from cerebellum
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med attachment of falx cerebri holds tentorium cerebelli up
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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
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extends almost vertically, inf to inf tentorium cerebelli
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free-edge projected slightly between cerebellar hemispheres
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occipital sinuses contained in fixed edge
Diaphragma Sellae •
small, circular, horizontal sheet of dura formsroof for hypophyseal fossa
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formed by dura surrounding pituitary gland a nd encircling its stalk
Arteries •
many meningeal aa. in periosteum supply most blood to periosteum, not meninges!
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only very fine branches of are distributed to dura
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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
14
•
•
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.
15
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. Top
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
16
•
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 Top
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 Extrinsic
Main action genioglossus
protrusion
hyoglossus
depression
styloglossus
retraction
palatoglossus
Nerve supply
CN XII
elevation
Pharyngeal plexus
17
Intrinsic
sup longitudinal muscle inf longitudinal muscle
they change the shape of the
CN XII
tongue
transverse muscle vertical muscle
Nerve Supply
Sensory
General Special
Motor
Ant Post lingual (CN V) glossopharyngeal chorda tympani (CN VII) 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 Top
Palate Hard Palate •
skeleton: palatine process of maxilla, horizontal plate of palatine
18
•
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. Top
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
19
•
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 Top
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 a round 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
20
•
•
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. Top
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
21
•
•
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 e thmoid 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
22
•
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 Top
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
23
•
•
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) Top
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
24
•
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
roof of orbit, ant to opticskin of upper eyelid
superioris
canal
lid
Superior rectus
common tendinous ring just post to sclerocorneal
elevate, adduct
CN III
elevates upper
junction Inferior rectus
depress, adduct
Medial rectus
adducts eye
Lateral rectus Superior oblique
CN VI body of sphenoid
runs through trochlea, post-sup CN IV
abducts eye depress, abduct
lat orbit Inferior oblique
maxilla in floor of orbit post-inf lat orbit
CN III
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
25
elevate, abduct
•
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
26
Lacrimal Artery •
supplies lacrimal gland, conjunctiva and eyelids Top
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 a nd 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 Course (divided by lat pterygoid) First
Branches
passes horizontally forwards between neck of mandible deep auricular
27
and lower border of pterygoid
ant tympanic mid meningeal accessory meningeal inf alveolar
Second
runs obliquely forward and upwards superf to inf head
to muscles of this region
of lat pterygoid
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
Main
Motor
med pterygoid m
trunk
(3)
Notes
tensor tympani m tensor palati m Sensory meningeal (1) Ant
Motor
massteric n to
28
division (3)
masseter m deep temporal nn. to temporalis n. to lat pterygoid
Post
Sensory buccal
usually runs between two heads of lat pterygoid, desc through deep
(1)
temporalis, supplies skin and mucous membrane of cheek
Motor
division (1)
n. to mylohyoid and ant digastric
Sensory auriculotemporal
encircles med meningeal a., breaks up into many branches, largest
(3)
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
29
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