Atlas of Human Anatomy by Netter

FACTS & HINTS

High-Yield Facts

Anatomic Points

A newborn's skull is large compared to other parts of the skeleton

Facial skeleton small compared to calvaria

Two halves of mandible begin to fuse during first year

The mastoid process is not present at birth but develops in the first 2 years of life

The anterior fontanelle:

A diamond-shaped region covered by a fibrous membrane

Lies at juncture of both frontal with both parietal bones

Ossifies by 18 months

Useful for assessing hydration and measuring heart rate and intracranial pressure

Enlargement of frontal and facial regions associated with increasing size of paranasal sinuses

Vertical growth of face because of dental development

Thinnest part of skull is pterion:

Where parietal bone articulates with greater wing of sphenoid.

Fractures can cause intracranial bleeding as pterion overlies anterior division of middle meningeal artery and vein.

Clinical Points

Skull (Calvaria) Fractures

Can occur as a result of direct trauma to the head

Can be one of several types:

Depressed

Produced by hard blows in regions where calvaria is thin

Fragment of bone forced inward into brain

Linear

Most frequent

Fracture lines radiate away from point of impact

Comminuted - bone broken into several pieces

Contre-coup

May be no fracture at impact site

Brain impacts opposite side of skull and rebounds to site of impact, with resulting bruising

May be associated with brain injury

When assessing a patient with a head injury the Glasgow Coma Scale (GCS) is useful..

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Clinical Points

Le Fort Fractures

Common variants of fractures of the maxillae, naso-orbital complex, zygomatic bones (midface fractures) were classified by Le Fort

(surgeon and gynecologist)

Le Fort I :

Horizontal fracture of one or both maxillae at the level of the nasal floor.

May present with crepitus on palpation and epistaxis

Rarely compromises airway.

Le Fort II:

Pyramidal-shaped fracture that includes horizontal fracture of both maxillae, extending superiorly through maxillary sinuses,

infraorbital foramina, and ethmoids to bridge of nose.

Separates central face from rest of skill

Places the airway at risk

Le Fort III:

Includes fractures of Le Fort II plus horizontal fracture through superior orbital fissures, ethmoid, and nasal bones, great wings of

sphenoid bones and zygomatic bones.

Maxillae and zygomatic bones separate from skull

May cause airway problems, nasolacrimal apparatus obstruction, and cerebrospinal fluid (CSF) leakage

Mnemonics

Memory Aids

Cranial/Orbital Bones: Occipital; Parietal; Frontal; Temporal; Ephnoid; Sphenoid

Old People From Texas Eat Spiders

Cranial Sutures: Sutures have CLASS

C Coronal

L Lambdoid

a And

S Squamous

S Sagittal.

Memory Aids