Skull, Sella Turcica, and Sinuses

Cranial vault or calvarium contains (4)
frontal bone, occipital bone, rt parietal, and lft parietal bones

Floor of skull contains (4)
ethmoid bone, sphenioid bone, rt temporal, and lft temporal bones

Bones of the skull are
thin flat bones, full density @ about 12 yrs

Bones of the skull have _ layers
3 layers-
1st-the outer layer (table) dense layer
2nd-Dipole (middle table) less dense, spongy layer containing major blood vessels and nerves that supply outer later with nutrients
3rd-the inner layer (table) less dense than outer layer

Frontal bone articulates with (7)
parietal (2)
zygoma (2)
maxilla (2)
lacrimal (2)
nasal (2)
ethmoid
sphenoid

Frontal bone portions (8)
squamous portion
frontal eminence
superciliary ridges
supraorbital margins
glabella
frontal air sinuses
nasion
horizontal portion

squamous portion of frontal bone
extended flat (plate like portion)

frontal eminence of frontal bone is located
on each side of mid sag plane of frontal bone

superciliary ridges of frontal bone correspond with
eye brow line

supraorbital margins of frontal bone are located
just under superciliary ridges. They are the sup. margin of orbital base

glabella is located
between superciliary ridges (raised portion)

frontal air sinuses are located
in the frontal bone (not symetrical/differ from person to person)

nasion is the
depressed area inferior to the glabella

horizontal portion of frontal bone forms
forms the orbital plate-roof of orbit. Receives cribiform plate of ethmoid. Articulates with lesser wings of sphenoid

Ethmoid bone portions (4)
Horizontal portion (cribiform plate), crista galli, perpendicular plate (vertical portion), labyrinths

Ethmoid bone is
small, cube shaped bone. Articulates with frontal and sphenioid bones

horizontal portion of ethmoid bone is called
cribiform plate. Fits into ethmoid notch of frontal bone. Olfactory nerves are located here.

Crista galli is
roosters comb, thick conical process on cribiform plate

perpendicular plate (vertical portion) of ethmoid bone makes
makes up superior portion of bony nasal septum

labyrinths of ethmoid bone contain
ethmoidal sinuses (ant/middle/post). The walls help form medial wall of orbits and part of lateral walls of the nasal cavity.

Nasal conchaes
project inferiorly from each medial wall of labyrinths. Thin, scroll shaped processes (superior and middle). Function to warm/moisten/filter air before going into lungs

Parietal bone articulates with
frontal bone anteriorly
temporal bone rt and lft
occipital-posteriorly
sphenoid bone
and opposite parietal bone

Parietal bones (2) are
square and have a convex external surface. presents a prominent bulge called parietal eminence

parietal eminence/tuberosity
prominent bulge on parietal bones near central portion of its external surface-widest point of head

Occipital bone is
densest bone in skull. located in post. inf. part of the cranium.

Occipital bone has (4) parts
foramen magnum
squamous portion
lateral condylar portions
basilar portion/clivus

formen magnum
contains inf portion of medulla oblongatta

Inion of occipital bone is
external occipital protuberance

Squamous portion of occipital bone
flat like extended plate like portion-curves post then sup from foramen magnum

lateral condylar portions of occipital bone
projects ant from lat side of squamous portion-makes up sides of foramen magnum

basilar portion/clivus
curves ant and sup to junction with body of greater wings of sphenoid

Sphenioid bone articulates with
frontal
parietal (both)
occipital
temporal (both)
ethmoid
vomer
zygoma
palatine

sphenoid bone is
irregularly wedge shaped bone. Situated at the base of the cranium ant to temporal bones and basilar part of the occipital bone.

sphenoid bone contains (4) portions
body
lesser wings (2)
greater wings (2)
pterygoid processes (2)

body of sphenoid contains
contains two sphenoidal sinuses which are separated by a median septum. Ant surface of body forms post bony wall of nasal cavity. Sup. surface presents deep depression called the sella turcica

Sella turcica
saddle shaped depression on sup portion of body of sphenoid. surrounds and protects pituitary gland. Lies at mid sag plane at a point 3/4 inch ant to and 3/4 in sup. to level of EAM. Bound ant by tuberculum sellae and post by dorsum sellae.

pterygoid process of sphenoid
paired processes. Post. projection below and behind sella turcica. 1 inch in length-serve as attachments for some muscles that move mandible

Greater wings of sphenoid
project from sides of sphenoid body

lesser wings of sphenoid
ant. to greater wings. Contain optic foramen-transmission of optic nerve impulses. Ant. clinoid processes are located here

Temporal bone are
irregular shaped bones and are situated on each side of the base of the skull between the greater wings of the sphenoid bone and the occipital bone.

Temporal bones contain (5) portions
Squamous portion
tympanic portion
styloid process
zygomatic process
petromastoid portion

squamous portion of temporal bone
thin upper portion. forms part of side wall of cranium and has a prominent arched process (zygomatic process)

Zygomatic process of temporal bone
projects ant to articulate with zygomatic bone of face to complete zygomatic arch

tympanic portion of temporal bone
situated below sqamous portion and ant to mastoid and petrous portions. Forms ant/inf/and part of post walls of EAM

styloid process of temporal bone
projects inf ant and slightly medial from inf portion of tympanic part of temporal bone

mastoid process of temporal bone
contain mastoid aircells, lower post portion of temporal bone. Sits inline with 1st cervical vertebrae. Communicates with tempanic cavity

petromastoid portions of temporal bone
petrous and mastoid portions together

petrous portion
thickest/densest portion of temporal bone. Houses organs for hearing. Can vary in degrees between coronal and mid sag plane

mesocephalic head-average
47* between coronal and mid sag plane

dolichocephalic head-narrow/long head
40* to mid sag plane

brachycephalic head-rounded
54* to mid sag plane

Ear portions (3)
Auricle/Pinna-outside cartilage
EAM-external auditory meatus
IAC-internal auditory canal

Sutures (4) are
Fibrous/immovable
coronal
sagittal
lambdoidal
squamosal

coronal suture
separates frontal and two parietal bones

sagittal suture
separates two parietal bones at midline

lambdoidal suture
separates two parietal bones from occipital bone

squamosal suture
separates parietal and temporal bones

temporomandibular joint (TMJ)
Ant to EAM-synovial condyloid. Coronoid process in mandible

Fontanels -soft spot
Bregma-ant junction of sagittal with coronal sutures-closed by 2 yr
Lambda- post junction of sagittal with lambdoidal suture-closes before bregma

Acanthion
midline junction of upper lip and nose

EAM (external acoustic meatus)
external opening into ear canal

Glabella
triangular area between eyebrows

Gonion
angle of mandible

infraorbital margin
inferior rim of orbital base

Inion/external occipital protuberance
bump midline at back of head

inner canthus
medial unction of upper and lower eyelids

mental point/mentum
triangular midpoint of chin

Nasion
slight depression at bridge of nose

supraorbital margin
superior rim of orbital base

outer canthus
lateral junction of upper and lower eyelids

vertex
most superior point of head

acanthomeatal line
EAM to acanthion

glabelloalveolar line
glabella to anterior alveolar process of maxilla

glabellomeatal line
EAM to glabella

infraorbitomeatal line
EAM to infraorbital margin

Interpupillary line (IPL)
transverse line between outer canthi

mentomeatal line (MML)
EAM to mental line

Midsagittal/Median sagittal plane
divides head into rt and lft halves

orbitomeatal line (OML)
EAM to outer canthus

air containing cavities located in (4)
maxillary bone
frontal bone
ethmoid bone
sphenoid bone

Maxillary sinus (antrum of highmore)
aerated slits at birth
expand to fill maxilla
pyramidal in shape
communicate with middle nasal meatus of the nose
floor at same level as upper teeth

Ethmoid air cells
visualized by age 6
located superiorly and posteriorly within ethmoid bone
lateral boundry is medial wall of orbit
composed of varying number of cells (3-18)
drain into nasal meatus

Sphenoid sinus
begin to develop at 2-3 yrs. Fully developed in adolescence
usually paired, drain into nasal cavity
sit in body of sphenoid bone below sella turcica
located close to base of floor of skull
air fluid level in sphenoid sinus following trauma may be sign of basal skull fracture

Frontal sinus
vary widely in size
walls are irregular
sound chamber which gives voice resonance
drain into nasal meatus

The hyoid bone belongs to the a. appendicular skeleton b. axial skeleton c. upper extremity d. skull axial skeleton The clavicle belongs to the a. axial skeleton b. pectoral girdle c. pelvic girdle d. upper extremity pectoral girdle WE WILL …

Functions of the skeletal system 1. Support= soft tissues and muscles attach to the skeleton 2. Protection= ribs protect underlying organs; skull protects the brain 3. Movement= attachment for muscles allows for movement 4. Hemopoiesis= the production of blood cells …

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