The Gross
Anatomy of the
Head and Neck:
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THE HEAD
Osteology of the skull
Introduction:
• superior part of the body that is attached to the trunk by the neck
Composition:
• the brain and its protective coverings, the ears, and the face
The Cranium
Introduction:
• The cranium (skull) is the skeleton of the head
Parts:
• has two parts:
 the neurocranium
 the viscerocranium
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Neurocranium (Cranial vault)
Introduction:
• is the bony covering (case) of the brain and its
membranous coverings, the cranial meninges.
• It also contains proximal parts of the cranial nerves
and the vasculature of the brain.
Parts:
The neurocranium has:
• a dome-like roof called the calvaria (skullcap)
• and a floor or cranial base (basicranium)
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Basicranium
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Composition:
• The neurocranium in adults is formed by a series of eight
bones:
 Four are singular bones
 and the other two sets of bones occur as bilateral pairs
 The four singular bones are:
 frontal
 ethmoidal
 sphenoidal
 occipital
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• While two sets of bones occurring as bilateral pairs are:
 Temporal
 parietal
note
 The ethmoid bone is an irregular bone that makes a relatively
minor midline contribution to the neurocranium but is primarily
part of the viscerocranium
Viscerocranium (facial skeleton)
• comprises the facial bones
• forms the anterior part of the cranium
• consists of the bones surrounding the mouth (upper and lower
jaws), nose/nasal cavity, and most of the orbits (eye sockets or
orbital cavities)
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Composition:
• consists of 15 irregular bones:
• Three are singular bones
• While 6 bones occur as bilateral pairs
 The three singuar bones are:
 Mandible
 Ethmoid
 Vomer
 The 6 bilateral paired bones are:
 Maxillae
 inferior nasal conchae
 zygomatic
 palatine
 nasal
 lacrimal bones
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 Note:
• The maxillae and mandible house the teeths
• They provide the sockets and supporting bone for the
maxillary and mandibular teeth.
• The Maxillae:
 contribute the greatest part of the upper facial skeleton,
 form the skeleton of the upper jaw
 It is fixed to the cranial base
• The Mandible :
 forms the skeleton of the lower jaw,
 It is movable because it articulates with the cranial base at the
temporomandibular joints (TMJs).
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Anterior or facial(frontal) aspect of the Cranium
Features include:
the frontal bone
zygomatic bones
orbits,
nasal region,
maxillae,
mandible
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The frontal bone
it is a squamous (flat) part
forms the skeleton of the forehead
articulates inferiorly with the nasal and zygomatic bones.
The supraorbital margin of the frontal bone has a supraorbital
foramen (notch) for the passage of the supraorbital vessels and
nerves
Just superior to the supraorbital margin is a ridge called the
superciliary arch
Between these arches is a smooth, slightly depressed area called the
GLABELLA
The Glabella is the anterior most projecting part of the forehead
Just above the glabella is a point on the midline of the forehead
called the Ophyron
On the midline of the mandible is the the most anterior point on the
mandible which is the most prominent part of the chin.
This point is called the pogonion
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• The intersection of the frontal and nasal bones is called the
NASION, a depressed area (bridge of the nose)
• The frontal bone also articulates with the lacrimal, ethmoid, and
sphenoids bones
The nasal region
• made up of a pair of nasal bones which are joined together at
midline by the nasal septum
• Inferior to these nasal bones is a pear shaped piriform aperture
• the bony nasal septum can be observed through this aperture
dividing the nasal cavity into the right and left parts
• On the lateral wall of each nasal cavity are curved bony plates
called the nasal conchae
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Maxillae
• form the skeleton of the upper jaw
• Occur in pairs
• The two maxillae are united at the intermaxillary suture in
the median plane
• their alveolar processes include the tooth sockets (alveoli) and
house the maxillary teeth
• They articulate with the frontal bone anteriorly and zygomatic
bones laterally
• On the body of the maxilla is the infraorbital foramen for
passage of the infraorbital nerve and vessels
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Mandible
• is a U-shaped bone
• forms the skeleton of the lower jaw
• Its alveolar process supports the mandibular teeth.
 consists of:
 of a horizontal part (the body)
 and a vertical part (the ramus )
• Inferior to the second premolar teeth are the mental
foramina for the passage of the mental nerves and vessels
• The base of the mandible has a midline swelling called the
mental protuberance
• Lateral to the mental protuberance on either side is a slightly
more pronounced bumps called the mental tubercles
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Zygomatic Bone
• Also known as cheek bone, malar bones
• On the lateral aspect of this bone is a foramen called the
zygomaticofacial foramen
• this foramen allows for the passage of the zygomaticofacial
nerve
• This bone articulates with the frontal, sphenoidal, maxillae and
temporal bones
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Clinical anatomy
 Injury to the superciliary arches
• The superciliary arches are relatively sharp bony ridges;
consequently, a blow to them (e.g., during boxing) may lacerate the
skin and cause bleeding. Bruising of the skin surrounding the orbit
causes tissue fluid and blood to accumulate in the surrounding
connective tissue, which gravitates into the superior (upper) eyelid
and around the eye
 Malar Flush
• The zygomatic bone was once called the malar bone.
• Clinically the term malar flush refers to redness of the skin
covering the zygomatic prominence (malar eminence), which is
associated with a rise in temperature in various fevers occurring
with certain diseases, such as tuberculosis
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Superior aspect of the skull
Also called the calvaria or skull cap
Bones forming it include
Frontal bone (unpaired)
Paired parietal bones
Occipital bone (unpaired)
The outer surface of the skull possess a number of landmarks
The frontal bone articulates with the paired parietal bones at
the coronal suture
The two parietal bones articulate with each other at the
sagittal suture
The paired parietal bones articulate with the occipital bones at
the lambdoid suture
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 The junction(intersection) between the coronal and sagittal sutures
is called the bregma
 The junction(intersection) between the sagittal suture and lambdoid
sutures is called the lambda
 The vertex is the most superior point of the skull near the midpoint
of the sagittal suture
 The parietal foramen on the parietal bone is variable, and it
allows for the passage of emissary veins
 Obelion: The region of the skull between the two parietal foramina
where the closure of the sagittal suture usually begins
Clinical Anatomy
Fracture of the Calvaria
 Depressed fractures:
 this can results from hard blows in thin areas of the calvaria in
which a bone fragment is depressed inward, compressing and/or
injuring the brain
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 Linear calvarial fractures :
 the most frequent type
 usually occur at the point of impact; but fracture lines often radiate away
from it in two or more directions
 Comminuted fractures:
 the bone is broken into several pieces.
 If the area of the calvaria is thick at the site of impact, the bone may bend
inward without fracturing; however, a fracture may occur some distance
from the site of direct trauma where the calvaria is thinner
 Contrecoup (counterblow) fracture:
 no fracture occurs at the point of impact, but one occurs on the opposite side
of the cranium
Obliteration of the Cranial Sutures
• The obliteration of sutures between the bones of the calvaria usually begins
between the ages of 30 and 40 years on the internal surface and
approximately 10 years later on the external surface
• Obliteration of sutures usually begins at the bregma and continues
sequentially in the sagittal, coronal, and lambdoid sutures
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Skull of a newborn baby
The halves of the frontal bone in the newborn are separated by the
frontal suture
the frontal and parietal bones are separated by the coronal suture
and the maxillae are separated by the intermaxillary suture
mandible consists of two halves united in the median plane by
the mandibular symphysis
this union begins during the 1st year and the halves are fused by
the end of the 2nd year
No mastoid process at birth
No styloid process
The mastoid processes form gradually during the 1st year
The bones of the calvaria of a newborn infant are separated by
membranous intervals called frontanelles
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They include:
anterior fontanelle
posterior fontanelle
paired sphenoidal fontanelle
Paired mastoid fontanelles
Anterior fontanelle
intro: the largest frontanelle
shape: diamond or star shaped
boundary: bounded by the halves of the frontal bone anteriorly and the
parietal bones posteriorly.
Location: at the junction of the sagittal, coronal, and frontal sutures, the
future site of the bregma
closure: By the 18 months of age, the surrounding bones have fused and the
anterior fontanelle is no longer clinically palpable
Frontal bone of a newborn
Union of the halves of the frontal bone begins in the 2nd year
In most cases, the frontal suture is obliterated by the 8th year
in approximately 8% of people, a remnant of the frontal suture persist called
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the metopic suture

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Posterior fontanelle
• Shape: is triangular
• boundary: bounded by the parietal bones anteriorly and the
occipital bone posteriorly
• location: at the junction of the lambdoid and sagittal sutures, the
future site of lambda
• Closure: begins to close during the first few months after birth and
by the end of the 1st year, it is small and no longer clinically
palpable
Sphenoidal and mastoid fontanelles
• overlain by the temporal muscle,
• fuse during infancy and are less important clinically than the
midline fontanelles
 note
• The halves of the mandible fuse early in the 2nd year
• The two maxillae and nasal bones usually do not fuse
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Molding of the calvaria
The softness of the cranial bones in infants and their loose connections at
the sutures and fontanelles enable the shape of the calvaria to change
(mold) during birth
During passage of the fetus through the birth canal, the halves of the
frontal bone become flat, the occipital bone is drawn out, and one
parietal bone slightly overrides the other
Within a few days after birth, the shape of the calvaria returns to normal
The resilience of the cranial bones of infants allows them to resist
forces that would produce fractures in adults
The fibrous sutures of the calvaria also permit the cranium to enlarge
during infancy and childhood
The increase in the size of the calvaria is greatest during the first 2 years,
the period of most rapid brain development
The calvaria normally increases in capacity for 15-16 years
After this, the calvaria usually increases slightly in size for 3-4 years as a
result of bone thickening
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Craniosynostosis and Cranial Malformations
• Premature closure of the cranial sutures is called craniosynostosis
results in several cranial malformations
• Premature closure of the sagittal suture, in which the anterior
fontanelle is small or absent, results in a long, narrow, wedge-shaped
cranium, a condition called scaphocephaly
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When premature closure of the coronal or the lambdoid suture
occurs on one side only, the cranium is a condition known as
plagiocephaly
• Premature closure of the coronal suture results in a high, tower-like
cranium, called oxycephaly or turricephaly
• oxycephaly or turricephaly is more common in females
 Note: Premature closure of sutures usually does not affect brain
development
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Lateral aspect of the skull
 This includes :
 lateral part of the neurocranium
 Lateral part of the viscerocranium (facial skeleton)
Composition:
• bones forming the lateral portion of the neurocranium include: the
frontal, parietal, occipital, sphenoid, and temporal bones
• bones forming the visible part of the facial skeleton include the
nasal, maxilla, and zygomatic bones and the mandible
• The main features of the neurocranial part are the temporal fossa,
the external acoustic opening, and the mastoid process of the
temporal bone
• The main features of the viscerocranial part are the infratemporal
fossa, zygomatic arch, and lateral aspects of the maxilla and
mandible
 The junction where the frontal, parietal, sphenoid(greater wing)
and temporal bone meet is called the pterion
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• It is usually indicated by an H-shaped formation of sutures

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Clinical anatomy
• The pterion is an important area because it overlies the middle
meningeal artery
• Fracture to the pterion can rupture the anterior branch of this
artery resulting in hematoma which exerts pressure on the
underlying cerebral cortex
• An untreated meningeal artery can cause hemorrhage which
can lead to death in a few hours
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The temporal bone of the lateral aspect of the skull
It has:
 a squamous part which articulates with the greater wing of sphenoid at
the sphenosquamous suture
 a zygomatic process which articulates with the zygomatic bone to
form the zygomatic arch
 a tympanic part which has the external acoustic meatus
 a petromastoid part which is usually separated into the petrous and
mastoid part
• A large bony prominence projects from the inferior border of the
mastoid part of the temporal bone called the mastoid process
• Medial to the mastoid process is the styloid process which projects
from the lower border of the temporal bone
• The point where the superior temporal line cuts the coronal suture is
called the stephanion
• While the located at junction of three sutures: parietomastoid,
occipitomastoid, and lambdoid is called the asterion
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Posterior aspect of the skull
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Bones include:
• Occipital bone
• Parts of the parietal bones
• Temporal bones (mastoid part)
Occipital bone
 The occipital bone is separated from the paired parietal bone
by the lambdiod suture
 Along the lambdoid suture are small bones called sutural or
wormian bones
 there is a midline projection called the external occipital
protuberance
 Curved lines extend laterally from this projection called the
superior nuchal lines
 The most prominent part of the external occipital protuberance
is the inion
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 About 1 inch (2.5cm) below the nuchal lines are additional 2 lines
called the inferior nuchal lines which curves laterally
 Extending downwards from the external occipital protuberance is
the external occipital crest
 In between the mastoid and the occipital in is the occipitomastoid
suture
Note
 Obliteration of Cranial Sutures
• The obliteration of sutures between the bones of the calvaria
usually begins between the ages of 30 and 40 years on the internal
surface and approximately 10 years later on the external surface
• Obliteration of sutures usually begins at bregma and continues
sequentially in the sagittal, coronal, and lambdoid sutures
 The region of the skull between the 2 parietal foramina where the
closure of the sagittal suture begins is called the OBELION
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Craniometric
Points of the
cranium
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The Internal surface of the cranial base (cranial cavity/fossae)
• has three large depressions that lie at 3 different levels:
 anterior crania fossa
 middle cranial fossa
 posterior cranial fossa
• These form the bowl-shaped floor of the cranial cavity
• The anterior cranial fossa is at the highest level(shallowest)
• while the posterior cranial fossa is at the lowest level(deepest)
 Sitting on the floor of the anterior cranial fossa is the frontal lobes
of the cerebral hemisheres
 Sitting on the floor of the lateral portion of the middle cranial fossa
is the temporal lobe, and in the midline of the middle crania fossa is
the pituitary gland
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 Sitting on the anterior portion of the floor of the posterior
cranial fossa is the brainstem (midbrain, pons and medulla
oblongata) and occupying the rest of the posterior cranial fossa
are the cerebellar hemispheres
 Note: the occipital lobe do not sit on the floor of the posterior
cranial fossa, it is the cerebellum that sit of the floor of the
posterior cranial fossa
Anterior cranial fossa
Introduction:
• Shallowest of the 3 cranial fossae
• Lodges the frontal lobe of the brain
Bony formation:
• Formed by 3 bones, namely:
 Frontal bone in the anterior and lateral directions
 Ethmoid bone in the middle portion
 2 parts of the sphenoid bone in the posterior portion
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• The part of the frontal bone in the anterior cranial fossa is the
orbital part/orbital surface
• The ethmoid bone of the anterior cranial fossa is made up of :
 A ridge which projects superiorly called the crista galli
 And a sieve- like cribriform plate of ethmoid which lies on each
sides of this ridge
• The 2 parts of the sphenoid bone in the anterior cranial fossa are:
 The jugum
 The lesser wing of sphenoid
Foramen
 The cribriform plate of ethmoid has numerous tiny foramina that
transmit olfactory nerves (CN 1) from the olfactory area of the
nasal cavity to the olfactory bulb of the brain
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• The frontal bone also has a bony median extension called the
frontal crest, at the base of the frontal crest is the foramen
cecum
• This foramen varies in size in different individuals, and is
frequently impervious; when open, it transmits the emissary
vein from the nose to the superior sagittal sinus
• This has clinical importance in that infections of the nose and
nearby areas can be transmitted to the meninges and brain
• Each lesser wing widens, curves posteriorly, and ends as a
rounded anterior clinoid process
• Just anterior to each anterior clinoid process is a circular
opening in the lesser wing of the sphenoid called the optic
canal
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• The optic canal allows for the passage of
 ophthalmic artery and
 optic nerve [CN II] to pass through as they exit the cranial
cavity to enter the orbit
Note: The optic canals are usually included in the middle cranial
fossa
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Middle crania fossa
• It is butterfly shaped
 separating the anterior and middle cranial fossae are the sharp
sphenoidal crests laterally and the sphenoid limbus centrally
 The sphenoid limbus forms the posterior boundary of the jugum and
the anterior boundary of the prechiasmatic sulcus
 (note: the prechiasmatic sulcus is bounded posteriorly by the
tuberculum sellae)
 The prechiasmatic sulcus is a smooth groove stretching between the
optic canals across the body of the sphenoid
Bony formation
• Formed mainly by the:
i. Parts of the sphenoid bone
ii. Parts of the temporal bone
 The parts of sphenoid involved are:
i. Sella turcica which is part of the body of sphenoid
ii. greater wings of sphenoid laterally
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Sella turcica
• Has 3 parts:
i. an anterior wall called the turberculum sella
ii. a posterior wall called the dorsum sella
iii. a deep central part lying in between the turberculum sella
and dorsum sella
 This central part is called the hypophyseal fossa, which
houses the pituitary gland
• On each side of the body of the sphenoid are four foramina
perforating the roots of the greater wings of the sphenoid,
these include :
i. Superior orbital fissure: a diagonal gap that separates the
greater wing from the lesser wing of sphenoid
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• This fissure allows for the passage of the:
 Cranial nerves III, IV and VI (occuomotor, trochlear and
abducens nerves)
 Ophthalmic division of trigerminal nerve (CN V1)
 ophthalmic vein
ii foramen rotundum: allows for the passage of the maxillary
division of the trigeminal nerve (CN V2)
iii foramen ovale: allows for the passage of the mandibular
division of the trigeminal nerve (CN V3)
iv foramen spinosum: allows for the passage of the middle
meningeal artery and the meningeal branch of mandibular
nerve
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Parts of the temporal bone include:
squamous part of the temporal bones laterally
and the petrous part of the temporal bones posteriorly
On the petrous part are grooves for both the greater and lesser
petrosal nerves
Posterolateral to the hypophyseal fossa is the foramen lacerum,
In life, it is closed by a cartilage plate
Only some meningeal arterial branches and small veins are
transmitted vertically through the cartilage
The lateral parts of the middle cranial fossa support the temporal
lobes of the brain
The boundary between the middle and the posterior cranial fossae is
the:
superior border of the petrous part of the temporal bone laterally
and a flat plate of bone, the dorsum sellae of the sphenoid, medially
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Posterior cranial fossa
Largest and deepest of the 3 cranial fossa
Lodges the brainstem (medulla oblongata, pons and midbrain)
and the cerebellum
Formed mainly by the occipital bone and the temporal bone
There is a slope that extend down from the dorsum sellae
leading to the foramen magnum called the clivus
posterior to the foramen magnum are cerebellar fossae which
accommodate the cerebellar hemispheres
The cerebellar fossae are partly divided by the internal
occipital crest into bilateral concave impression
The internal occipital crest ends superiorly in a bony
prominence called the internal occipital protuberance
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Grooves and foramen in the posterior cranial fossa
• internal acoustic meatus: passage of facial nerve (CN VII) and
vestibulochear nerve (CN VIII)
• Jugular foramen: allows the passage of:
 3 cranial nerves pass through it, which are cranial nerves IX, X
and XI {glossopharyngeal,vagus and accessory nerve}
 2 important venous structures, the dura venous sinuses, coming in
from the posterior side is the sigmoid sinus and from the anterior
side is the inferior petrosal sinus
 Note: these two sinuses enter the jugular foramen and when they
emerge from the other side, they fuse together and once fused
together, they are called the internal jugular vein
• hypoglossal canal: located superior to the anterolateral margin of
the foramen magnum and allows for the passage of the
hypoglossal nerve {CN XII}
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• Foramen magnum: allows for the passage of;
 The spinal cord which is continuous with the medullar
obongata
 The two vertebral arteries
 The spinal contribution of accessory nerve, the spinal
accessory nerve
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