Cranium of the skull copy
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Transcript of Cranium of the skull copy
Correlative Clinical Anatomy of the Head
Joel G. Soria, MD
Development of the skull
The base of the skull develops by endochondral ossification
The brain and cranial nerves develop before the skull, so when the chondrocranium develops, its components form around the nerves and form foramina.
The chondrocranium ossifies from a number of centers.
The last piece of cartilage to ossify is between the body of the sphenoid bone and the occipital bone, just anterior to the foramen magnum: this is the spheno-occipital synchondrosis. Its epiphyseal plate exists for the growth in length of the base of the skull and it ossifies at age 25.
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: � the neurocranium / Cranial Vault � the viscerocranium / Facial Bones
The Head
The head is formed mainly by the skull with the brain and its covering meninges enclosed in the cranial cavity.
The special senses, the eye and the ear, lie within the skull bones or in the cavities bounded by them.
The brain gives rise to 12 pairs of cranial nerves, which leave the brain and pass through foramina and fissures in the skull.
All the cranial nerves are distributed to structures in the head and neck, except the 10th, which also supplies structures in the chest and abdomen.
Bony Anatomy
Bones of the Skull
The skull is composed of several separate bones united at immobile joints called sutures. The connective tissue between the bones is called a sutural ligament. The mandible is an exception to this rule, for it is united to the skull by the mobile temporomandibular joint.
The bones of the skull can be divided into those of the cranium and those of the face. The vault is the upper part of the cranium, and the base of the skull is the lowest part of the cranium.
Skull
divided into CRANIUM (neurocranium) and FACIAL BONES (viscerocranium)
Cranium
Consists of 8 bones, which form the calvarium and the cranial base – Calvarium composed of external and internal tables of compact bone separated by a layer of spongy bone (diploe) – Cranial base articulates with the atlas, the bones of the facial skeleton, and the mandible
Frontal bone: 1
Parietal bones: 2
Occipital bone: 1
Temporal bones: 2
Sphenoid bone: 1
Ethmoid bone: 1
Craniumfacial bones
Zygomatic bones: 2
Maxillae: 2
Nasal bones: 2
Lacrimal bones: 2
Vomer:1
Palatine bones: 2
Inferior conchae: 2
Mandible: 1
Cranium
A - Frontal B - Parietal (2) C - Occipital D- Temporal (2) E - Sphenoid F - Ethmoid
Quick Hints CRANIAL BONES
All cranial bones are
unpaireD EXCEPT
PARIETAL and
TEMPORAL bone
Memory Aide CRANIUM
what are the bones
that compose the
cranium
S
T
E
P
O
F
STEP OFF MY SKULL
PHENOID
EMPORAL
THMOID
ARIETAL
CCIPITAL
ACIAL
Memory Aide CRANIUM
Suture
Bones of the cranium are joined by sutures
coronal suture (A) - frontal bones and parietal bones
sagittal suture (B) - parietal bones
lambdoidal suture (C) - parietal bones and occipital bone
Pterion
Junction of the frontal, parietal, sphenoid and temporal bones
Thinnest part of the calvarium
Superficial to the anterior branch of the middle meningeal artery
Clinical Correlate SKULL FRACTURE AT PTERION
lateral skull fracture at the pterion may lacerate the middle meningeal artery
– result: epidural hematoma – CT scan: biconvex lens-
shaped hematoma
– Hx/PE: initial lucid asymptomatic interval, followed by deterioration
fontanelles
At birth, the anterior fontanelle is a diamond-shaped area between the 2 frontal bones and the 2 parietal bones.
It pulsates and bulges when the baby cries.
It closes by 18 months to 2 years and is then known as the bregma
anterior fontanelle
triangular in form and situated at the junction of the sagittal suture and lambdoidal suture
Generally closes in 6–8 weeks from birth.
A delay in closure is associated with congenital hypothyroidism.
Posterior fontanelle
bregma
superior aspect of the skull anterior to the vertex
︎ junction of the frontal and sagittal sutures
LAMBDA
posterior aspect of the skull superior to the external occipital protuberance
junction of the sagittal and lambdoid sutures
Facial Skelton
Formed by 14 bones enclose the orbits, nasal
cavity, oral cavity, and paranasal sinuses
Facial Bones
A - Zygomatic (2) B - Maxillae (2) C - Nasal bones (2) D - Lacrimal (2) E - Vomer F - Palatine (2) G - Inf concha (2) ︎ H - Mandible
Quick Hints CRANIAL BONES
All Facial bones are
unpaireD EXCEPT
vomer and mandible.
Cranial base
Divided into 3 shallow compartments: A - anterior cranial fossa B - middle cranial fossa C - posterior cranial fossa
Contain foramina and fissures that transmit blood vessels, and cranial nerves and their branches
Anterior cranial fossa
Anterior cranial fossa
APERTURE BONE CONTENTS Perforations in cribriform
plate Ethmoid CN I
middle cranial fossa
F. RotundumF. Ovale
F. Spinosum
Optic Canal
F. Spinosum
Superior orbital fissure
middle cranial fossa
APERTURE BONE CONTENTS
Optic canal Lesser wing of sphenoid
CN II, ophthalmic artery
Superior orbital fissure
Between lesser and greater wings of sphenoid
CN III, IV, V1, VI, superior ophthalmic vein
F. rotundum
Greater wing of sphenoid
CN V2
F. ovale CN V3, lesser petrosal nerve
F. spinosum Middle meningeal artery
Foramen lacerum
Petrous temporal and sphenoid
Internal carotid artery
posterior cranial fossa
posterior cranial fossa
Memory Aide CRANIUM
Through which skull
openings do the branches
of the trigeminal nerve
(CN V) EXIT ?
Memory Aide CRANIUM
S-R-O
foramen Spinosum = V1 (ophthalmic) foramen Rotundum = V2 (maxillary) foramen Ovale = V3 (MANDIBULAR)
Clinical Correlate NEONATAL SKULL
Disproportionately large cranium relative to the face
Growth of maxillary sinus, mandible and maxilla facilitates increase in length
Absent mastoid process at birth (develops in first 2 years of life)
Clinical Correlate FONTANELLE
unossified membranous intervals (fontanelles)
– anterior fontanelle • diamond-shaped• closed by 18 mos
– posterior fontanelle• triangle-shaped• closed by end of first year
︎ depressed in dehydration
︎ bulging in increased ICP
︎ ping-pong ball-like
Clinical Correlate BASILAR SKULL FRACTURE
most common in the middle cranial fossa
︎ clinical manifestations – epistaxis
– CSF otorrhea
– CSF rhinorrhea
– hemotympanum
– Raccoon eyes • periorbital ecchymoses
– Battle sign • mastoid
Clinical Correlate NASAL FRACTURE
mostcommonfacialfracture– becauseoftheprominenceofthenose
︎ mostaresimpleandarereducedunderlocalanesthesia
Clinical Correlate MAXILLOFACIAL FRACTURE
Clinical manifestations – extensive facial swelling – midface mobility– teeth malocclusion – CSF rhinorrhea– diplopia ︎ Classified using the Le Fort System
Clinical Correlate MAXILLOFACIAL FRACTURE
Clinical Correlate MAXILLOFACIAL FRACTURE
Clinical Correlate MAXILLOFACIAL FRACTURE
Clinical Correlate BLOWOUT FRACTURE
Trauma may tear the orbital floor, causing displacement into the maxillary sinus
︎ damaged structures– paper thin portion of the
ethmoid (lamina papyracea) – infraorbital nerve
• altered sensation to the skin of the cheek, upper lips and gums
Clinical Correlate BLOWOUT FRACTURE
depressed fractures– most dangerous type– pond fracture in children ︎ comminuted fractures– broken into several pieces ︎ linear fractures – most frequent type – at the point of impact (coup) or opposite (countercoup)