The Skull (Cranium and Face)

What is the neurocranium?

the bones that support or protect the brain

What is the viscerocranium?

the bones that support the soft tissues of the face and aid in eating, drinking, chewing, speaking

How many bones make up the cranium and what are they?

8, the frontal bone, occipital bone, temporal bones (two), parietal bones (2), sphenoid and ethmoid

Supraorbital margin of frontal bone

the sharp ridge that forms the border between the forehead and inside of the orbit

supraorbital foramen of frontal bone

opening above each orbit allowing blood vessels and a small branch of CN V1 nerve to pass

frontal sinus of frontal bone

Cavity within the bone that is lined with muscosa and open to the exterior. It lightens the skull and alters vocal quality

anterior cranial fossa

the portion of the cranial cavity formed by the frontal bone

foramen magnum of occipital bone

opening through which spinal cord connects to lower brain

external occipital protuberance

bump on back of head where the trapezius and ligmentum nuchae attach

superior nuchal line of occipital bone

site of muscle attachment for trapezius, occipitalis, and splenius capitis muscles

inferior nuchal line of occipital bone

site of muscle attachment for obliquus capitis superior muscle, rectus capitis posterior major muscle, and rectus capitis posterior minor muscle

occipital condyles of occipital bone

rounded processes that articulate with the atlas (C1)

hypoglossal canal of occipital bone

Hypoglossal (CN XII) runs through, inner aspect of occipital condyle

groove for transverse sinus

occipital bone depression

posterior cranial fossa

portion of cranial canal formed by the occipital

sphenoid bone

greater wing of sphenoid bone

posterior and inferior to lesser wing on the interior of the skull, also visible in the posterior orbit and lateral side of the skull

lesser wing of sphenoid bone

One of two side wings extending from the body of the sphenoid bone

medial pterygoid plate of sphenoid bone

site for tendon attachment, articulates with vomer and palatine processes of sphenoid

lateral pterygoid plate of sphenoid bone

sharp process that laterally and inferiorly projects from the sphenoid, attachment for lateral pterygoid muscle

foramen ovale of sphenoid bone

mandibular branch CN V3 (of trigem) passes through

foramen spinosum of sphenoid bone

surrounded by grooves for middle meningeal vessels and meningeal branch of mandibular nerve

foramen rotundum of sphenoid bone

passage for maxillary branch of the trigeminal nerve (V2)

sphenoid sinuses

in body of sphenoid

superior orbital fissure of sphenoid bone

Between greater and lesser wing on the sphenoid bone, transmits oculomotor, trochlear, and abducens nerves. Also a branch of opthalmic CN V1

optic canal of sphenoid bone

passage of the optic nerve (CN II) and ophthalmic artery

body of sphenoid bone

central section of sphenoid

sella turcica of sphenoid bone

houses the pituitary gland

ethmoid bone

Light spongy bone between the eye sockets; forms part of the nasal cavities.

crista galli of ethmoid bone

superior projection in the middle of the cribriform plate of the ethmoid bone; providing a point of attachment for the dura mater, helping to secure the brain within the skull

cribriform plate of ethmoid bone

The horizontal plate of the ethmoid bone separating the cranial cavity from the nasal cavity. Where the olfactory bulb sits and CN I synapses

perpendicular plate of ethmoid bone

superior portion of the bony nasal septum

Inferior nasal conchae

two bones that help to complete the nasal cavity by forming the side and lower wall (superior and middle portions are from the ethmoid)

external auditory meatus of temporal bone

tube-like opening for the ear canal

mastoid process of temporal bone

insertion of sternocleidomastoid

styloid process of temporal bone

attachment for stylohyoid ligament,

stylomandibular ligament, styloglossus muscle (innervated by the hypoglossal nerve)

stylohyoid muscle (innervated by the facial nerve)

stylopharyngeus muscle (innervated by the glossopharyngeal nerve)

mandibular fossa of temporal bone

Articulates with the head (condoloid process) of the mandible to form the temporomandibular joint. The mandible (lower jaw) joins with the skull at this site.

zygomatic process of temporal bone

extension from the temporal bone that forms the posterior portion of the zygomatic arch, attachment point for temporal fascia

squamous part of temporal bone

large flat bone posterior to the sphenoid bone and inferior to the parietal bone, very thin

petrous portion of temporal bone

Thick portion of the temporal bone; hearing and balance are housed here

foramen lacerum

jagged opening filled with cartilage in a living person, formed by space between the borders of the temporal, occipital and sphenoid bones, transmits multiple blood vessels

carotid canal of temporal bone (within petrous part)

Opens into Foramen Lacerum, transmits internal carotid artery

jugular foramen

a large opening at the inferior surface that transmits the jugular vein, glossopharyngeal nerve (CN IX), vagus nerve (CN X), and spinal accessory (CN XI) and some blood vessels

stylomastoid foramen of temporal bone

opening for an artery and cranial nerve VII (facial)

internal auditory meatus of temporal bone

Passageway for nerves and vessels that supply the ear (CN VIII, vestibulocochlear, and CN VII, facial)

middle cranial fossa

holds the temporal lobes of the brain

grooves for middle meningeal vessels of parietal bones

groove for superior sagittal sinus of parietal bone

right down the two hemispheres this groove exists

How many bones make up the face and what are they?

vomer, hyoid, mandible, and pairs of : maxillae, nasal bones, inferior nasal conchae, zygomatics, palatines, and lacrimals

Mandible Body (Mandible)

horizontal portion of the mandible

mandible angle

where the body and ramus of the mandible meet, attachment of the masseter laterally, and the pterygoideus internus (medial pterygoid muscle) medially; the stylomandibular ligament is attached to the angle between these muscles.

mandible ramus

vertical extension of the body on either side

coronoid process of mandible

insertion of temporalis

head of mandible

round portion at the top of the condylar process; articulates with temporal mandibular fossa

alveolar part of mandible

houses the teeth in dental alveoli (sacs)

frontal process of maxilla

the ascending part of the upper jaw which gradually protrudes as it rises beside the nasal bone to meet the frontal bone; the ascending process of the upper jaw.

body of maxilla

Horizontal part of upper jaw superior to teeth

zygomatic process of maxilla

articulates with zygomatic bone

alveolar process of maxilla

curved, inferior margin of the maxilla that supports and anchors the upper teeth

maxillary sinus

sinus on either side of the nasal cavity below the eyes

palatine process of maxilla

forms hard palate

zygomatic frontal process

The lateral rim of the eye socket formed by a process of the frontal bone and a process of the zygomatic bone.

temporal process of zygomatic bone

short extension from the zygomatic bone that forms the anterior portion of the zygomatic arch

maxillary process of zygomatic bone

the part of the zygomatic bone that joins with the maxilla

horizontal plate of palatine bone

forms posterior part of hard palate

palatine bones

vomer bone

forms the base for the nasal septum

hyoid bone

a U-shaped bone in the neck that supports the tongue.

nasal bones

form the bridge of the nose

inferior nasal conchae

The lowermost scroll-shaped bones on the sidewalls of the nasal cavity.

lacrimal bones

make up part of the orbit at the inner angle of the eye

What is the calvarium?

skull cap, portion of neurocranium consisting of the frontal, parietal and occipital bones

What is the cranial base?

floor of the neurocranium, consisting of all the neurocranial bones

Why don't the cranial sutures fuse until age 25?

unfused sutures can move as the fetus passes through the birth canal and there are multiple periods of rapid brain growth through adolescence

coronal suture

the suture between the parietal and frontal bones of the skull

Bregma

junction of coronal and sagittal sutures

sagittal suture

between the two parietal bones

lambdoid suture

between parietal bones and occipital bone

lambda

junction of sagittal and lambdoidal sutures

parietal foramen

parietal emissary vein passage

What are craniometric points (pterion, bregma, lambda) used for?

anatomical landmarks during surgeries

pterion

Junction of frontal, parietal, sphenoid, and temporal bones. Structural vulnerability as it is thin and middle meningeal artery is just deep, so hard head blow can result in subdural hematoma

What is different about the way the flat bones of the skull form and what is this process called?

intermembranous ossification, they don't have an intermediate cartilaginous stage

What is the diploe of a flat bone?

the spongy area between layers of compact bone

What are sinuses?

air pockets in the bones of the skull (pneumatized)

What makes sinuses vulnerable to infection?

They are continuous with the nasal cavity

What are the paranasal sinuses?

frontal, sphenoid, ethmoid, maxillary

What is the purpose of having sinuses?

1. reduce weight of skull

2. humidify and heat inhaled air

3. increase resonance of speech

4. protect vital structures during facial trauma

What are the features of the neonate skull?

large cranium and small face, mandibular division that fuses into mandibular symphysis, prominent fontanelles

What are fontanelles?

fibrous membranes connecting the cranial bones, anterior, posterior, sphenoid and mastoid

What might a raised anterior fontanelle mean?

brain inflammation

What might a sunken fontanelle mean?

dehydration

What is craniosynostosis and how is it corrected?

the premature ossification of 1 or more sutures resulting in bulging at the fontanelle at the contralateral side. Treated by helmets and or surgery

metopic craniosynostosis

fusion of the frontal suture resulting in elongation at the forehead

Sagittal Craniosynostosis

premature closure of sagittal suture resulting in posterior elongation

unicoronal craniosynostosis

one-sided closure of the coronal suture resulting in bulging at the contralateral forehead

lambdoid craniosynostosis

closing of one side of the lambdoid suture resulting in posterior bulging at the contralateral side