The Skull

Areas of Anatomy

1) Gross anatomy: part listing of the human body; studied by region or by system2) Microscopic anatomy: histology3) Developmental anatomy: embryology4) Functional anatomy: physiology5) Radiographic anatomy: study of the human body using x-rays

- Anatomical position: body upright, with palms and hands facing forward, and feet close together

- Body defining planes: 1) Coronal plane: passes from one side to another dividing the body into anterior and posterior parts2) Sagittal plane: passes from front to back dividing the body into right and left parts. Mid-Sagittal

is when the right and left parts are exactly equal, the dividing line passing in the middle3) Transverse plane: passes from side to side and front to back horizontally dividing the body into

superior and inferior parts

- Relative anatomical terms:

o Anterior = ventral = front

o Posterior = dorsal = back

o Superior = cephalic = upper

o Inferior = caudal = lower

o Proximal = closer to origin

o Distal = away from origin

o Superficial = close to surface

o Deep = away from surface

- Movement of body parts :

o Extension = returning part to normal position

o Flexion = bending body part ( forward movement of body part)

o Abduction = moving part away from position; laterally

o Adduction = moving part closer to body; medially

o Rotation = along 1 axis, its either external (lateral) or internal (medial)

o Circumduction = combined complex movement

o Protrusion = forward movement of the mandible

o Retraction = moving mandible back to its place

- Basic body tissues and parts:

o Tendons: fibrous connective tissue band which originates from the skeletal muscle and

inserts into the bone. o Aponeurosis; fibrous connective tissue that forms a flat sheet. it lies between parts of the

bodyo Fascia: a covering structure which surrounds and divides large spaces in the body to smaller

compartmentso Borsa: synovial structure that is found between, tendon-tendon, tendon-bone, it produces

synovial fluid for lubrication

Body Systems:

1) Nervous system: a. Central nervous system: brain and spinal cordb. Peripheral nervous system: cranial nerves (12 pairs arise from the brain), spinal nerves (31

pairs arise from spinal cord) and autonomic nervous system.

Spinal cord:

o Contains dorsal horn, which is located at the dorsal aspect. It is completely sensory

o Contains ventral horn, located at the ventral aspect. It is completely motor

o Dorsal root arises from dorsal horn while ventral root arises from ventral horn

o Dorsal root passes through dorsal root ganglion, ventral root passes through ventral root

gangliono After passing through ganglia they form together spinal nerves

o They then divide into ventral and dorsal rami both being mixed

(Sensory and motor)

2) Mucoskeletal system : has 3 main componentsa. Joints: where 2 or more bones come together

i. Bony joints: immovable (pelvis, sutures)ii. Relatively movable: fibrocartilage

iii. Freely movable: synovialb. Muscles: smooth, skeletal, cardiac

i. Skeletal: it is for movement, it is named based on1. Function: extensor, abductor, etc2. Shape: deltoid3. Size: maximus, minimus4. Attachment: temporalis5. Length: short, long

c. Bones: 2 typesi. Axial skeleton: lies in the center (ex: pelvis)

ii. Appendicular: has similar right and left parts

Note: nerves are either sensory or motor or both

Sensation

General Special

Pain Vision

Touch Taste

Temprature Hearing

Pressure Smelling

Nervous and endocrine systems are responsible for body function.

Bone is classified according to being:ShortLong (ex: arm & forearm)Flat (ex: skull)Irregular (vertebrae)Pneumatic: contains air cavitiesSesamoid: bone that lie in the tendon (ex: patella)

Synovial Joints

Synovium is the membrane that produces the synovial fluid, it is important for lubrication and reduction of friction.

It is a weak structure, thus surrounded by fibrous joint capsule to prevent it’s separation during movement.

Joint stability is achieved by:

1) Joint capsule2) Shape of the bone forming the joint3) Ligaments4) Muscles around the joint

The skull is part of the axial skeleton

It is composed of 22 bones:

- 21 firmly joined together by sutures

- Mandible: a single movable bone which articulates with the skull at the TMJ (a synovial joint)

The 22 bones are either single or paired (one on each side)

Bones are either facial or cranial

Note:

The hard palate is formed by the Maxillary bones (anterior 1/3) and the palatine bones (posterior 2/3)

It is not necessary to have all the structures to

achieve stability

6 Single Bones 8 Paired BonesMandible MaxillaryFrontal Nasal

Occipital ZygomaticSphenoid Inferior Nasal conchaeEthmoid Parietal Vomer Temporal

Lacrimal Palatine

Views of the Skull

Outside views

Superior

Inferior = Basal

Posterior = occipital

Anterior = Frontal

Lateral = Temporal

1) Anterior View: frontal

Bones present in this view are: frontal, nasal, lacrimal, maxillary, mandibular, zygomatic, vomer, inferior conchae

a. Frontal bone: convex in shape, forms foreheadb. Orbit: opening of the eyes. Has 4 orbital margins

i. Supraorbital margin: formed by frontal boneii. Medial orbital margin: formed by fontal (superiorly), maxilla (inferiorly)

iii. Infraorbital: formed by zygoma, and maxillaiv. Lateral orbital margin: frontal (superiorly), zygomatic (inferiorly)

Landmarks of the orbit:

1) Supraorbital notch/foramen: in the superior orbital margin for transmission of vessels and nerves. Painful if pressed on

2) Superciliary arch: a bony elevation lying above the supraorbital margin. (eyebrows lie exactly above the margin)

3) Glabella: hairless region between the supraciliary arches. Clinical significance: 1- skin turgidity can be measured in patients suspected of dehydration. 2- glabellar reflex, in which a person’s forehead is taped several time and the subject blinks, if the blinking persists, which is called Myerson’s sign, being an early symptom of Parkinson’s disease, dementia and neurological disorders

4) Nasion: root of the nose, depressed area between the 2 orbits

5) Infra-orbital foramen: located in the anterior surface of the maxilla on the same line vertically with the supra-orbital foramen

6) Anterior nasal apertures: (nasal openings), their boundaries are the 2 nasal bones superiorly, maxillary bone laterally, maxillary bone inferiorly

7) Zygoma: 2 bones below the orbit

8) Inferior and middle nasal conchae (superior are hidden and not seen in frontal view)

Superior and middle nasal conchae are part of the ethmoid but the inferior nasal concha is a separate bone

9) Alveolar processes

a. Of the maxilla, have sockets that carry the maxillary teethb. Of the mandible, containing sockets for the mandibular teeth

2) Lateral View: also called the temporal view

Landmarks of the lateral view:

a. Anterior nasal spine: union of 2 maxillary bones at the lower border or the anterior nasal apertures

b. Nasal septum: divides nasal cavity vertically into 2 cavities nasal septum is divided into 3 parts: anteriorly nasal cartilage, inferiorly vomer, superiorly perpendicular plate of the ethmoid.

c. Lateral orbital margind. Temporal lines: they are either superior and inferior or one single linee. Zygomatic arch: formed by the zygomatic process of temporal bone and the temporal

process of the zygomatic bonef. Temporal fossa:

i. Region limited by temporal lines superiorly and zygomatic arch inferiorlyii. Formed by: frontal, parietal, greater wing of sphenoid and temporal bones

iii. Gives rise to temporalis muscleiv. Pterion:

1. H-shaped region2. Lies above anterior branch of middle meningeal artery3. Very thin bone, easily fractured leading to injury of underlying artery

which will result in intercranial, epidural or extradural hematoma. May compress the brain tissue

g. External acoustic meatus: auditory tube, posterior to the TMJh. Mastoid process:

i. Conical bony projection behind ear, pulpable areaii. Contain air filled cells, function in?????

iii. Provides attachment to muscles and ligaments???????i. Styloid process: deep, not pulpable, attaches muscles and ligaments (styloid apparatus)j. Paranasal air sinuses: air filled cavities which open into the nose

i. Frontalii. Maxillary

iii. Sphenoidiv. Ethmoid

3) Superior View: calvaria

Bones present are: frontal bone, right and left parietal bones, occipital bone

Landmarks:

a. Coronal suture: between frontal bone and the 2 parietal bonesb. Sagittal suture: between the 2 parietal bonesc. Lambdoid suture: between the 2 parietal and the occipital bonesd. Bregma : meeting point of coronal and sagittal suturese. Lambda: meeting point of lambdoid and sagittal suturesf. Parietal foramen: in the parietal bones, for transmission of emissary veins (veins which

connect venous blood from the outside to the inside)

Neonatal skull:

- Sutures are not well joined together Sagittal suture looks like an arrow Metopic suture: lies between the 2 frontal bones and ossifies by the age of 5 Anterior fontanelle: unossified “bregma”, ossifies by the age of 18 month to form

bregma Posterior fontanelle: unossified “lambda”, ossifies by the age of 9 month to form

lambda They function to assess the intercranial pressure by palpation (bulge if high

and depress if low pressure)

4) Posterior view:- Landmarks of the posterior view:

Sagittal Suture Lambdoid Suture External Occipital protuberance: a projection in the squamous part of the occipital

bone Nuchal lines: superior and inferior extending from the lateral part of the external

occipital protuberance Temporal Bone Parietal Bone Occipital Bone Maxillary Bone Mandibular Bone

5) Inferior view:

12 pairs of cranial nerves which pass through the openings in the inferior viewI. OlfactoryII. OpticIII. OcculomotorIV. TrochlearV. AbducentVI. Trigeminal

i. V1 ophthalmicii. V2 Maxillary

iii. V3 MandibularVII. Facial VIII. VestibulochoclearIX. GlossopharyngealX. VagusXI. Accessory XII. Hypoglossal

Landmarks of the inferior view:1) U-Shaped maxilla2) Hard palate: separates oral from nasal cavity, anterior 2/3 formed by maxilla, posterior 1/3 formed by

the horizontal plate of the palatine bone3) Palatine process of the maxilla4) Sphenoid bone

a) Greater wingb) Lesser wingc) Medial and lateral pterygoid processesd) Body of the sphenoid

5) Pterygoid fossa: lies between the medial and lateral pterygoid processes and gives attachment to pterygoid muscles

6) Infratemporal fossa: exposed by removal of the zygomatic arch and the mandible, it’s boundaries are:a) Anteriorly: maxillab) Posteriorly: styloid processc) Laterally: zygomatic arch or ramus of the mandibled) Medially: lateral pterygoid plate

7) Posterior nasal openings: nasal choanae, communicates the nasal cavity to the oropharynx it’s boundaries are: a) Superiorly: body of the sphenoidb) Inferiorly: horizontal plates of the palatine bonec) Medially: vomerd) Laterally: medial pterygoid processes

8) Temporal bone:

Muscles of mastication:

1) Temporalis2) Masseter3) Medial pterygoid4) Lateral pterygoid

a) Zygomatic processb) Squamous partc) Petrous partd) Styloid processe) Mastoid processf) Tympanic plate

6) Cranial base of the skull:

- Contains several openings and foramina through which the nerves and blood vessels pass

- Occipital condyle: bony mass on each side of foramen magnum and articulates with atlas (C1) to form atlantooccipital joint

Opening positionStructures passing through

Cribriform plate Part of the Ethmoid bone Olfactory bulb/fibers (from olfactory nerve I)

Optic canal At root of lesser wing Optic nerve IIOphthalmic artery

Supraorbital fissure

Communicates the orbital canal and middle cranial fossa, between lesser and greater wings of sphenoid

Oculomotor nerve IIITrochlear nerve IVOphthalmic nerve V1

Abducent VI

Superior and inferior ophthalmic veins

Foramen Rotundum

In greater wing of sphenoid, communicates middle cranial fossa with pterygopalatine fossa

Maxillary nerve V2

Foramen Ovale In greater wing of sphenoid , communicates middle cranial to Infratemporal fossa

Mandibular nerve V3

Foramen lacerum

Between body of the sphenoid and Petrous part of temporal bone

Greater Petrosal nerve (a branch of the facial nerve VII, which then leaves through the stylomastoid foramen)

Foramen spinosum

In greater wing of the sphenoid, communicates middle cranial fossa to Infratemporal fossa

Anterior branch of the middle meningeal artery

Carotid canal In Petrosal part of temporal bone, opens into posterior wall of foramen lacerum

Internal carotid arterySympathetic nerve plexus

Internal acoustic meatus

Intracranially, in the posterior surface of the Petrous part of the temporal bone

Facial nerve VIIVestibulocochlear nerve VIII

Stylomastoid foramen

Between styloid and mastoid processes of the temporal bone

Facial nerve VII (pure motor branch)

Jugular foramen Between occipital bone and Petrous part of temporal bone

Glossopharyngeal IXVagus nerve XAccessory nerve XIInternal jugular veinsSigmoid sinusPosterior meningeal arteryInferior Petrosal venous sinus

Condylar canal Anterior to occipital condyle Emissary veins

Hypoglossal canal

Posterior to condyle Hypoglossal nerve XII

Foramen magnum

Occipital bone Spinal root and its covering meningesSpinal root accessoriesVertebral artery

The spinal root arises from the spinal cord then enters the skull through foramen magnum to join with the cranial root and leave jugular foramen as accessory nerve

Vertebral arteries supply posterior part of the brain

Cranial Fossae

1) Anterior cranial fossa:Boundaries: from Squamous part of the frontal bone to the lesser wing of the sphenoidContents: frontal lobes of brainFloor is formed by: Cribriform plate of the Ethmoid bone , it lies between the nasal cavity and the

anterior cranial fossa (part of floor of ACF and roof or nasal cavity) Crista galli: upward bony projection (from cribriform plate) which attaches to falx

cerebri Orbital plate of frontal bone

2) Middle cranial fossa:

Boundaries: lesser wing of sphenoid anteriorly to petrous part of temporal bone posteriorlyIt is composed of 2 lateral portions, a central portion formed by superior surface of the body of the sphenoidThe central portion includes sella turcica (also called the hypophyseal fossa or pituitary fossa). Tuberculum sellae: anterior limit of sella turcice. Dorsum sellae: posterior limit of sella turcica

Great petrosal

Floor: Greater wing and body of sphenoid Squamous part of temporal bone Part of Petrous part of temporal bone

3) Posterior cranial fossa: - Boundaries: upper border of Petrous part of temporal bone anteriorly and Squamous part of

occipital bone Posteriorly- Contains: the cerebellum

- Landmarks: Internal occipital protuberance: projection in the inner surface opposite to the

external occipital protuberance Sigmoid sulcus: S-shaped sulcus, contains the sigmoid venous sinus Sulcus for Transverse Sinus: contains the transverse venous sinus

Meninges

They are 3 membranes which surround the brain and spinal cord.

I. Pia mater: delicate layer directly attached to the brain and spinal corda. Subarachnoid space: space that lies between the Arachnoid mater and the Pia mater.

Contains CSF (cerebrospinal fluid) which act as a cushion to protect the brain and spinal cord

II. Arachnoid mater: transparent layer, which lies over the Pia mater. It shows trabeculations (arachnoid granulation villi), which function in the drainage of the CSF and the venous blood in the venous sinuses

a. Subdural Space: contains blood vesselsIII. Dura mater: tough layer which lies over the Arachnoid mater

Cranial dura: consists of periosteal layer (endosteal layer) which is the lining of the skull bone, and the real dura mater, which is the tough fibrous layer

a. Epidural Space: lies between dura mater and bone. Contains blood vessels

IAMStylomastoid

foramenForamen lacerum

Facial nerve

Before the facial nerve enters the internal acoustic meatus, it gives a branch to the

greater petrosal nerve, which then leaves through foramen lacerum. The facial nerve leaves the Stylomastoid foramen as pure

motor

Facial

Dura Mater

The Dura mater is separated into 2 layers called the dural folds or projections, they separate different brain hemispheres.

I. Falx Cerebri: a. separates the 2 cerebral hemispheresb. Double layer of dura which separate the 2 cerebral hemispheresc. Attached anteriorly to crista gallid. It has 2 borders:

i. Upper: superior Sagittal sinus lies in itii. Lower border: inferior Sagittal sinus lies in it

II. Falx Cerebelli: a. separates the 2 cerebellar hamispheres

III. Tentorium Cerebelli: a. separates the cerebellum from the occipital lobes of the cerebrumb. Forms a tent over the posterior cranial fossa

IV. Diaphragm Selli:a. Very small dural projection that form the roof of sella turcicab. Has an opening in the middle for the stalk of the pituitary gland

Dural Venous Sinuses

Venous channels which lie between the 2 layers of the Dura mater. They lack valves and smooth muscles in their walls, as blood flows with gravity.

Single Sinuses Paired Sinuses

Superior Sagittal Venous Sinus Transverse Venous Sinus

Inferior Sagittal Venous Sinus Sigmoid Venous Sinus

Straight Sinus Cavernous Venous Sinus

Superior Petrosal Sinus

Inferior Petrosal Venous Sinus

Single Sinuses

I. Superior Sagittal venous sinus:a. In the upper border of the falx cerebrib. Runs upwards and backwards ending at the internal occipital protuberance

II. Inferior sagittal venous sinus:a. In the lower border of the falx cerebrib. Joins with the great cerebral vein to form the straight sinus, which runs upwards and

mediallyIII. Straight Sinus:

a. Formed by the union of the great cerebral vein and the inferior petrosal venous sinusb. Runs at the meeting point of the tentorium cerebella and falx cerebric. Ends at the internal occipital protuberance

Paired Sinuses

I. Transverse Sinus: a. Right transverse sinus: continuation of the superior Sagittal sinusb. Left transverse sinus: continuation of the straight sinusc. Passes lateral to the internal occipital protuberance on both sides

II. Sigmoid Sinus:

a. Continuation of the transverse sinusb. Ends at the jugular foramen forming the jugular bulb which then continues as internal

jugular veinIII. Cavernous Sinus:

a. Cave like, lies in body of the sphenoidb. It has a special importance as some important structures pass through it

i. Vessels: internal carotid arteryii. Nerves: Occulomotor III, Trochlear IV, Abducens VI, V1 & V2 of trigeminal V

c. Infection in the dangerous zone (angle between mouth and eye) can easily transmit it into the brain by the following pathway:Facial Vein pterygoid venous plexus inferior ophthalmic vein cavernous sinus

IV. Superior petrosal sinus:a. Arises from the upper posterior part of the cavernous sinusb. Runs in the upper border of the petrous part of the temporal bone, to joining the sigmoid

venous sinusV. Inferior petrosal sinus

a. Arises from lower part of cavernous sinusb. Joins internal jugular vein, from outside the skull after passing through the jugular

foramen

Any problem in the cavernous sinus affects movement of

eyeball, sensation of the face, blood supply to the brain

c. It’s the only venous sinus that leaves the skull with the venous blood

Individual Bones of the Skull

1) Maxilla: a paired bone which has 4 processes and 4 surfaces

- 4 surfaces : Superior: it separates the orbital cavity from the maxillary air sinuses Anterior: facial Posterior: forms anterior limit of infratemporal fossa Medial (nasal): forms lateral wall of the nasal cavity

- 4 processes: Frontal: joins the frontal bone to form the medial orbital margin Zygomatic: joins the zygoma to form the infra orbital margin Alveolar: Contains sockets for upper teeth Palatine: joins palatine bone to form the hard palate

- Articulations of the maxilla: frontal, nasal, zygomatic, inferior nasal concha, palatine bone, ethmoid, maxilla

- Maxillary nasal sinuses are located in the medial (nasal) process. It is one of the biggest sinuses and functions in resonance of voice and lightening of weight of skull

2)Mandible: A

single bone,

horseshoe shaped, which is composed of a body and 2 rami- The body: composed of 2 surfaces (inner and outer) and 2 borders (superior and inferior)

Outer surface: Mental protuberance: lies in the midline Mental tubercle: lies on both sides of the protuberance Mental foramina: located below the apices of the premolar-molar. Can be

used to determine the age of a person as it is closer to the inferior border in infants and closer to the superior border in elderly people, in adults it lies in the middle. (the change in position is relative as the bone is not completely grown in infants and is resorbed in elderly)

Oblique line: also called the external oblique ridge, extends from mental foramen to the anterior border of the ramus

Inner surface: Superior and inferior mental spines (genial tubercles): 4 projections which

lie in the midline which give attachment to: Superior: genioglossus muscle Inferior: geniohyoid muscle

Mylohyoid line: gives attachment to mylohyoid muscles which are 2 muscles join to form the floor of the mouth

Sublingual fossa: a depression which lies above the mylohyoid line. Contains the sublingual salivary glands

Submandibular fossa: a depression which lies below the mylohyoid line. Contains the submandibular salivary gland

Digastric fossa: located below the genial tubercle

- The Ramus: each has 2 surfaces(medial and lateral),2 processes (anterior/coronoid and posterior/condylar) and 2 borders (anterior and posterior)

- Ramus meets the body to form the angle of the ramus Surfaces:

Lateral: smooth except where it gives attachment to the massetter muscle Medial surface:

Mandibular foramen: opens to the mandibular canal which ends at the mental foramen, transmitting the inferior alveolar nerve and blood vessels. Mental nerve is the continuation of the inferior alveolar nerve, supplies lower teeth and lip, thus anesthesia is given in it.

Lingula: bony projection, lies anterior to mandibular foramen. Provides attachment to ligaments.

Rough region in the lower part of inner surface, gives attachment to the medial pterygoid muscle.

Processes: Coronoid/anterior: gives attachment to temporalis Condyle/posterior:

Head: articulates with mandibular fossa of temporal bone forming TMJ

Neck : provides attachment to capsule of TMJ

3) Sphenoid Bone: a single bone has the shape of a butterfly.It is composed of:

- Body- 2 greater wings- 2 lesser wings- 2 pterygoid processes

Body:o Has 2 surfaces:

Superior: forms sella turcica/pituitary fossa/ Inferior: forms upper margin of coanae and upper border of pharynx

o Sphenoid air sinuses: Upper border: sella turcica Lower border: roof of pharynx Visible in the anterior view

Greater wing of sphenoid:o Has 4 surfaces:

Cranial surface Lateral surface: temporal Inferior : infratemporal , roof of infratemporal fossa orbital

Between the lesser and greater wings lies the superior orbital fissure Pterygoid plates/processes:

Medial and lateral processes/plates in between them lies the pterygoid fossa

The ramus is sandwiched by the massetter muscle from outside and medial pterygoid from the

inside

The pterygoid fossa provides attachment to the medial and lateral pterygoid muscles

The pterygoid fossa can be seen only in the posterior view Optical canal is located at the roof of lesser wing and above superior orbital

fissure, while rotundum is below superior orbital fissure Above the pterygoid plate lies the pterygoid canal (transmits the pterygoid

nerve) Ovale, rotundum and spinosum are present on the greater wing but are not

visible in the anterior or posterior view. Articulations of the sphenoid bone:

o Palatine bone, ethmoid, nasal bone, temporal , vomer, frontal, parietal, occipital, zygoma, maxilla

4)Ethmoid: single

bone, lies between the 2 orbits

- it is also located in:o upper part of nasal cavityo roof of nasal cavityo perpendicular plate of the ethmoid, forms part of the nasal septumo lateral wall of ethmoid forms the medial wall of the orbito medial wall of the ethmoid forms the lateral wall of the nasal cavity

- the labyrinth contains air filled cavities (ethmoidal air cells), each haso medial/ nasal plate

has 2 projections: superior and middle nasal conchaeo lateral/orbital plate

- cribriform plate separates the nasal cavity from the anterior cranial fossa

To differentiate between medial and lateral views of the nasal cavity: in the medial view the septum is present

5) Frontal Bone: single bone, developed from 2 halves, which are separated by the metopic suture (ossifies at the age of 5 years)

- It is composed of 2 processes: o Maxillary: articulates with the maxilla to form medial orbital margino Zygomatic: articulates with the zygoma to form lateral orbital margin

- In the upper orbital margin lies the supraorbital foramen/notch- Supraciliary arch: lies above the supraorbital margin (below the eyebrow)- Glabella: hairless area between the supraciliary arches- Frontal nasal sinuses: 2, which drain the nasal cavity

o They are lined by the same epithelium of the nasal cavityo They function in:

Weight reduction Sound resonance

- Squamous part: o Forms the vault and forehead

o Forms the floor of the anterior cranial fossao Forms the roof of the orbital cavity

- Foramen cecum: lies anterior to crista galli, for transmission of emissary veins

6) Temporal Bone: paired bone, on the lateral sides of the skull, composed of 5 partsSquamous, petrous, mastoid, styloid, tympanic

- Squamous: o Vertical flat parto Forms part of the floor of the temporal fossao Has the zygomatic process which articulates with the zygoma to form

the zygomatic archo Mandibular fossa: inferior to zygomatic process. Site of articulation with

the condyle- Tympanic plate:

o Anterior limit of external acoustic meatus- Mastoid process:

o Conical, palpable bony projection, lies behind the earo Contains air filled cavities (mastoid air cells) o For resonance of soundo Gives attachment to sternocleidomastoid muscle and posterior belly of

Digastric muscleo Gives attachment to ligaments

- Styloid process:o Deeply seated, non-palpableo This downwardly projected bony processo Gives attachment to:

Stylohyoid muscle Stylopharyngeal muscle Styloglossus muscle Stylohyoid ligament

o Stylomastoid foramen lies between the styloid and mastoid processes- Petrous part:

o Sometimes called petromastoid (closely related to mastoid)o Hard rock like bony part containing important structures

Ear cavity (through internal acoustic meatus) Carotid canal (transmits internal carotid artery and sympathetic

plexus) Facial nerve

Chorda tympani exits between the tegmen tympani and anterior edge of tympanic plate

Vestibulocochlear nerve

7) Occipital bone: single flat bone, forms posterior part of the skull and part of the base of the skull- Squamous part: The curved, expanded plate behind the foramen magnum

o Superior and inferior nuchal lines which project laterally from the external occipital protuberance

o Internal occipital crest: projection which lies posterior to the foramen magnum (internally)

o Internal occipital protuberance (internally)o Has transverse groove for transverse sinus (internally)

- Basilar part: the thick part in front of the foramen magnum, o Projects anteriorly, forming part of the roof of the pharynx (pharyngeal

tubercle)- Articulates with part of the sphenoid

8) Nasal bone: a paired bone- Join in the midline

forming part of the roof of the nasal cavity

9) Zygomatic bone: paired bone, forms the prominence of the cheek- Articulates with frontal, maxillary, greater wings of sphenoid and temporal bone

10) Lacrimal bone: paired bone- Forms part of the medial wall of the orbit- Nasolacrimal duct: a canal that connects the orbit to the nasal cavity (for the

drainage of tears)

11) Palatine bone: paired bone, L-shaped- 2 plates:

o Horizontal: forms the posterior third of the hard palate and the projecting nasal crest forms part of the nasal septum

o Perpendicular plate: forms lateral wall of the nasal cavity

12) Inferior nasal conchae: paired bones- Attached to lateral wall of the nasal cavity- A fragile bone- Increases surface area of nasal cavity- Lined by mucous membrane

13) Vomer: single bone, a thin deep plate- Articulates with

o Maxillao Ethmoido Sphenoido Septal cartilage

(inferiorly)

Nasal septum: vomer, septal cartilage,

perpendicular plate of the ethmoid

Face

The face extends from the hair to the lower border of the mandible and from the ear to the ear

Contents of the face:

- Skin: includes hair follicles, sweat glands and sebaceous glands- Connective tissue: has superficial fascia only, no deep fascia- Muscles: mastication and facial expression muscles- Blood Vessels: arteries and veins- Glands: parotid and submandibular glands- Nerves: trigeminal and facial nerves

Muscles of facial expression:

- Responsible for expression- Control size of facial openings (each has sphincter/closes

o Moutho Noseo eyes

- Arise from facial skeleton and are inserted into skin- Arise from 2nd branchial arch- Supplied by facial nerve

Muscles of the Eyes:

Name of Muscle Sphincter / Dilator Function

Orbicularis oculiPeripheral/orbital partCentral/palpebral part

sphincter

Whole muscle: helps move tears towards midline of face

Orbital part: forceful closurePalpebral part:gentle closure

Frontalis Dilator Elevates eyebrows, and wrinkles forehead, opens the eye

Levator palpebrae superioris

Dilator Elevates upper eyelid, only muscle supplied by the occulomotor nerve

Muscles of the nostrils:

Name of Muscle Sphincter/dilator FunctionDilator naris Dilator Dilates opening of nose

Compressor naris Sphincter Closes opening of nose

Muscles of the Mouth:

Name of muscle Sphincter/dilator functionOrbicularis oris Sphincter Arises from the maxilla and

mandible, brings the 2 lips together (whistling action)

Zygomaticus major and minor Dilator Elevates the angel of the mouthLevator labii superioris Dilator Elevates the upper lip upwards

Levator anguli oris Dilator Lies between the zygomaticus major and minor, elevates angel

of mouthDepressor labii inferioris Dilator Moves lip downwards

Depressor anguli oris Dilator Moves angel of mouth downwards

Mentalis Dilator Depressing of chinResorius Dilator Moves angle of mouth

horizontallyPlatysma Dilator Depression of lower lip,

tightening of the skin of the neck

External Carotid Artery

Common Carotid Artery

Internal Carotid

Facial ArterySuperficial Temporal

Artery

Maxillary Artery

Infraorbital Artery

Mental Artery

Ophthalmic Artery

Supratrochlear Artery

Supraorbital Artery

Superficial Temporal

Vein

Facial Vein Retromandibular Vein

External and Internal Jugular

Veins

Trigeminal Nerve V

Ophthalmic division V1

Maxillary Division V2

Mandibular Division V3

Skin of the face from the angle of the eye upwards. Upper eyelid skin, anterior

and lateral parts of the nose, forehead

From angle of the eye to the angle of the mouth. Lower

eyelid, skin of cheeks, upper lip

Angle of the mouth downwards. Parotid

region, lower lip, chin, lateral side of the scalp

Muscles of the Cheek:

Buccinator Muscle: lie between massetter and angel of mouth

- Anterior fibers mix with orbicularis oris muscle

- Pierced by the duct of the parotid gland

- Functiono Blowing

o Pushing food out of the vestibule into the oral cavity proper

Blood Supply of the Face

1) Arterial blood supply:

2) Venous drainage:

Nerve Supply of the face

Sensory for the skin

Motor for the muscles

Sensory Supply:

Motor Supply:

All muscles of facial expression are supplied by the facial nerve (VII) except the levator palpebrae superioris muscle which is supplied by the occulomotor nerve (III)

Facial Nerve gives 5 motor branches:

- Temporal

- Zygomatic

- Buccal

- Mandibular

- cervical

Facial Palsy: damage to the facial nerve

It leads to:

paralysis to ½ of the face inability to whistle inability to close eyes leading

To dry and ulcerated cornea inability to blow angle of mouth droops causing saliva to come out face will shift towards normal side

Parotid Region

It is the area in the side of the face inferior and anterior to the ear

salivary glands in the parotid region are:o parotid: the largest salivary gland

o submandibular

o sublingual

o scattered small salivary glands in the submucosa of the cheeks

saliva is eithero serous (water like)

o mucous (thicker)

o it helps in digestion, turning food into a bolus thus making swallowing easier and also

helps in speech1) parotid salivary glands:

- 1 on each side: wedge shaped, exocrine gland

- It has 3 surfaces: o Anteromedial surface: faces the massetter muscle, medial pterygoid

muscle and ramus of mandibleo Posteromedial surface: faces the mastoid process and

sternocleidomastoid muscleo Lateral surface: faces the skin and great auricular nerve

- Surrounded by parotid capsule which is a continuation of the investing layer of the deep fascia

- Stansen’s duct: the opening of the parotid gland. Starts from the anterior border of the gland and then passes through the massetter and turns medially to pierce the buccinator muscle then pens into the vestibule opposite to the upper second molar

- Structures that pass within the parotid gland:

o Facial nerve

o Retromandibular vein

o External carotid

arteryo Auriculotemporal

nerve

Facial Nerve: enters the parotid gland without supplying it from the posteromedial surface, dividing it into a deep lobe and a superficial lobe. It ends within the parotid gland giving five terminal motor branches (temporal, zygomatic, Buccal mandibular, cervical)

Structures passing into the parotid gland:

1) Veins- Superficial vein and maxillary

vein join into the gland to form the retromandibular vein.- The retromandibular vein then divides into anterior and posterior divisions

- The anterior division joins the facial vein to form the common facial vein which extends as the internal jugular vein

- The posterior division joins the great auricular vein to form the external jugular vein

Parotid gland

Superficial temporal Retromandibular

Maxillary

Facial Common Facial

Internal jugularAnt. division

2) Arteries:- External carotid enters the gland and ends in it by giving superficial temporal

artery and maxillary artery

Nerve Supply of the gland

1) Sensory: a. by auriculotemporal nerve which is branch of V3 b. carries pain sensation from the capsule of the parotid gland

2) Autonomic:a. Sympathetic:

i. By sympathetic plexus surrounding external carotid arteryii. Decreases salivation and secretions (dry mouth)

b. Parasympathetici. By glossopharyngeal carried by the lesser petrosal nerve

ii. The salivary nuclei located in the brain is responsible for the production of salivaiii. The preganglionic parasympathetic, stops to relay in otic ganglia, located in the

infratemporal fossaiv. Post ganglionic fibers runs to the parotid gland with the auriculotemporal nerve

Blood Supply of the gland:

- Arterial blood supply: through external carotid artery and terminal branches of superficial temporal artery and maxillary artery

- Venous drainage: through maxillary vein and superficial temporal vein of the retromandibular

Lymph nodes:

- Drainage is by the parotid lymph nodes and the deep cervical lymph nodes

Mumps: viral infection of the parotid gland

Parotitis: bacterial infection of the parotid gland

Posterior division

External jugularGreat

auricular

Damage to the gland can lead to damage to the facial nerve

Otic Ganglia

Post ganglionic Parasympathetic

Secretomotor Fibers

Pre ganglionic Parasympathetic

Secretomotor Fibers

Lesser Petrosal Auriculotemporal

The Orbit

2 cavities, pyramidal in shape, located in the anterior view of the skull

Each orbit has:

- Base: directed forwards- Apex: directed backwards- 4 orbital margins- 4 walls

I. Roof: separates the orbital cavity from the anterior cranial fossa. Formed from lesser wing of sphenoid and orbital plate of frontal bone

II. Floor: separates orbit from maxillary air sinuses. Formed from maxilla and zygomaIII. Lateral wall: separates orbit from temporal fossa, formed from zygomatic bone and

greater wing of the sphenoidIV. Medial wall: separates orbital and nasal cavities, formed from lacrimal, labyrinth of

ethmoid bone and part of palatine bone

- Openinings in the orbit:1. Superior orbital fissure: communicates with the middle cranial fossa2. Optic canal: communicates with the anterior cranial fossa/middle cranial fossa3. Infra-orbital fissure: communicates with the pterygopalatine fossa4. Supraorbital notch: communicates with the anterior surface of forehead5. Infraorbital notch: communicates with the face

6. Nasolacrimal duct: connects the nasal cavity to the orbit- Contents of the orbit

I. EyeballII. MusclesIII. NervesIV. Blood vesselsV. FatVI. Lacrimal apparatus

VII. Ciliary ganglion

I. Eyeball : spherical in shape, camera of the body, consists of 3 layersa. Outer layer: a fibrous coat that protects the eye. Formed from sclera and cornea

i. Sclera: 1. provides attachment to the muscles2. white in color3. protects the eyeball

ii. cornea:1. transparent part

b. Middle layer: also called the vascular coat. i. Choroid: becomes enlarged anteriorly to form the Ciliary body

ii. iris: a forward extension of the Ciliary body which gives the color of the eye (pigmented coat)

iii. pupil: an opening in the middleiv. 2 muscles of the eye for visual adaptation (affected by the amount of light)

1. Constrictor pupilae: is stimulated by high light intensity and is under parasympathetic control

2. Dilator pupilae: is stimulated by absence of light, under sympathetic control

v. Lens: connected to Ciliary body by suspensory ligamentsvi. Ciliary muscles: group of involuntary muscles in Ciliary body

1. Change thickness of lens by changing length of suspensory ligaments2. Allows for visual accommodation (ability to see far and near)

c. Inner layer: nervous coat called the retinai. Has many photsensory receptors (rods and cons)

1. Rods: for dark light2. Cons: for daylight, colors and moving objects

ii. Optic nerve: originates from the retina from the rods and consiii. Fibers travel posteriorly from the rods and cons to form the optic nerveiv. Fundus: site of attachment of the optic nerve to the eyeball. It has no rod and

cons, thus it’s a blind spot- Chambers of the eyeball: divided because of presence of lens

d. Anterior chamber: contains aqueous humor (an aqueous watery fluid)e. Posterior chamber: contains vitreous humor (jelly like fluid) it gives the round shape of

the eyes

- Eyelids: f. Conjunctiva:

i. the lining of the eyelids ii. a transparent membrane inner surface which turns to line the eyeball

iii. inflammation can occur leading to red itchy eyes (conjunctivitis)II.

Fat: a. Allows eye to move freely within the bony orbitb. Supports the eyeball

III. Muscles There are 2 groups of muscles in the eye

1. Intraocular: muscles inside the eyeballa. Constrictorb. Dilatorc. Ciliary muscles

2. Extraocular: muscles inside the orbit (outside the eyeball)a. Recti (meaning straight)

i. Superior rectusii. Inferior rectus

iii. Medial rectusiv. Lateral rectus

b. Oblique

Nerve Supply:

LR6 SO4 3

i. Superior obliqueii. Inferior oblique

c. Levator palpebrae superioris

Movements of the Eyes

Right eye Left eye Movement Superior Rectus3 Superior rectus3

Inferior Rectus3 Inferior Rectus3

Lateral Rectus6 Medial Rectus3

Medial Rectus3 Lateral Rectus6

Inferior Oblique3 Superior Rectus3

Superior Rectus3 Inferior Oblique3

Superior Oblique4 Inferior Rectus3

Inferior Rectus3 Superior Oblique4

Testing the function of the nerves through eye movements:

- Abducens VI: look lateral by left eye- Trochlear IV: look down and lateral by

right eye- Occulomotor III: look at any other

direction

Problems With the eye: - Convergent Squint/diplopia/strabismus:

double vision created when both eyes move medially

- Divergent Squint; when one eye moves normally and the other eye moves laterally

IV. Nerves :a. Optic nerve II:

i. pure sensory nerve for visionii. arises from the retina and goes into the brain

iii. Nasal part of retina views pictures coming from lateral/ temporal sideiv. Lateral part of retina views vision from medial side, these are called visual fieldv. The two fibers join to form the optic nerve

vi. Nasal fibers of the optic nerves cross the midline forming the optic chiasma, it contains nasal fibers of both eyes

The remaining cranial nerves arise from the brain stem

Decussation: crossing of fibers to

the opposite side

vii. Optic tract: the continuation of the nasal fibers of the opposite side eye and the temporal fibers of the eye on the same side

viii. The optic tract ends in the visual cortex of the occipital lobe of the brain

Optic chiasma is closely related to

the pituitary gland, thus any damage to the pituitary gland affects the chiasma

If someone receives a hit in the back of

the brain, it can affect vision (visual

cortex)

Damage to the optic nerve: one eye is blindDamage to chiasma: bitemporal hemianopia (blindness of the fields from the lateral side)Damage to optic tract: contralateral hemianopia (blindness of the temporal of one eye and nasal of the other eye)

Nerves passing through the optic cavity:

1. V1 of the trigeminala. Pure sensory nerveb. Enters the orbit through superior orbital fissurec. Branches:

i. Lacrimal: sensory, supplies lacrimal gland, conjunctive and the skin of the upper eyelidii. Frontal: ends by giving 2 terminal branches

1. Supraorbital : supply upper eyelid, scalp, skin of the forehead, and frontal air sinuses

Damage to the occulomotor causes: 3D

Diplopia

Drooping of upper eyelid= ptosis

Dilated pupil

2. Supratrochlear : supply upper eyelid, scalp, skin of the forehead, and frontal air sinusesiii. Nasociliary:has 2 parts:

a. Visceral secretomotor: receives post ganglionic parasympathetic fibers from ciliay ganglia to supply the Ciliary body (muscles of the iris=constrictor pupilae) and lacrimal gland

b. Sensory: supplies nasal cavity, skin of the nose, skin of upper eyelid and ethmoidal air cells2. Occulomotor nerve: arises from the brain stem and enters the orbit through the superior orbital fissure.

Has 2 components:1. Motor: to all muscles of the orbit except the superior oblique and the lateral rectus2. Parasympathetic: preganglionic fibers which pass through the ciliary ganglia to supply the

ciliary muscles (constrictor pupilae). It’s also responsible for visual accommodationa. To test the function of the Trochlear:

ii. Defect in eyeball movementiii. Drooping iv. Light reflex

3. Trochlear: arises from the brain stem.a. Enters orbit through superior orbital fissureb. Pure motor nervec. Supplies only superior oblique

4. Abducens arises from the brain stem.a. Enters orbit through superior orbital fissureb. Pure motor nervec. Supplies only lateral rectus

5. V2 of the trigeminal: pure sensorya. Leaves skull through foramen Rotundum, to go to pterygopalatine fossab. Enters the orbit and become Infraorbital nerve, which runs in the floor of the orbit and leaves the

orbit through the Infraorbital foramenc. Supplies

I. the skin of the face form angle of the eye to the angle of the mouthII. nasal cavity

III. maxillary air sinusIV. upper teethV. part of the pharynx

d. Branches:I. Posterior superior alveolar nerve.

II. Middle superior alveolar nerveIII. Anterior superior alveolar nerve

V. Ciliary Ganglia: small pin head sizes parasympathetic gangliaa. Functionally related to occulomotor nerveb. Receives preganglionic fibersc. Postganglionic fibers pass through the nasociliary nerve

VI. Blood Vessels a. Arteries: ophthalmic artery,

The pterygopalatine ganglia is suspended

by V2, but is functionally related to the facial nerve

i. a branch of internal carotid artery ii. enters the orbit through optic canal, and ends by giving terminal branches

1. supraorbital 2. Supratrochlear

iii. Before entering the orbit it gives central retinal artery which runs in the center of the optic nerve

iv. Damage can result in blindness, as it supplies the retinab. Vein:

i. Superior ophthalmic vein: formed by union of supra orbital, Supratrochlear and angular veins

ii. Inferior ophthalmic vein: forms by small veins in the orbit joined together and drain into the cavernous sinus

iii. Both leave the obit VII. Lacrimal Apparatus: contains

a. Lacrimal glandb. Canaliculic. Lacrimal sacd. Nasolacrimal duct

- Lacrimal gland: I. an exocrine gland, II. produces and secretes tearsIII. located in upper lateral side of the orbitIV. has 2 parts

large orbital part small palpebral part

V. receives its parasympathetic fibers from facial nerve, carried by greater petrosal nerveVI. tears flow on the anterior surface of the eyeballVII. blinking distributes the tears to moisten the eyeballVIII.All tears will accumulate in the medial angleIX. Superior and inferior punctums: openings in the medial surface of the eye (corner) which

pass the tears on to the canaliculi- Canaliculi: small ducts which drain the tears to the lacrimal sac, closely related to the medial wall

of the orbit- Nasolacrimal duct: connects the lacrimal sac to the wall of the nasal cavity, thus making a pathway

for draining the tears (passes through lacrimal bone)- Tears are then absorbed by the nasal mucosa- Nasal mucosa inflammation: blocked opening = teary eyes - Crying: excessive tear production, therefore inability of mucosa to absorb it all, leading to runny

nose

The end