Class notes
Chapter 7 - Axial Skeleton
- Course
- Institution
These notes in Anatomy were used during my 1st year in nursing school and greatly helped me become the Registered Psychiatric Nurse that I am today! :D
[Show more]
Seller
Followgaddielmatira
Content preview
HLSC 120 – Human AnatomyChapter 7: Axial Skeleton
▪ There are 206 bones in an adult skeleton Nasal septum – thin ridge of bone that subdivides the nasal cavity into left and right
Skeletal system is divided into 2 parts: halves
Axial skeleton – composed of bones along the central axis of the body (3 regions: Inferior nasal conchae – found along the lateral walls of the nasal cavity; 2 scroll-
skull, vertebral column, thoracic cage); create a framework that supports and shaped bones
protects the organs; houses special sense organs; provides areas for the attachment SUPERIOR VIEW – shows 4 of the cranial bones
of skeletal muscles Coronal suture – articulation b/w the frontal and the parietal bones
Hemopoietic tissue – found in spongy bone of most axial skeleton; Sagittal suture – connects the left and right parietal bones almost exactly in the
responsible for blood cell formation midline of the skull
Appendicular skeleton – consists of bones of the appendages (upper and lower Parietal foramen (single) / foramina (paired) – found along the posterior one-third
limbs, as well as the bones that hold the limbs to the trunk of the body) of the saggital suture; conducts tiny emissary veins from the veins of the brain to
SKULL the veins of the scalp; number can vary b/w individuals
composed of both cranial and facial bones Lambdoid suture – its superior part represents the articulation of the occipiral bone
Cranial bones – form the rounded cranium w/ both parietal bones
cranium – completely surrounds and encloses the brain; made up of 8 POSTERIOR VIEW – shows the occipital bone, lambdoid structure, and portions of
bones (unpaired ethmoid, frontal, occipital, sphenoid bones, paired parietal and temporal bones
parietal and temporal bones) w/c provide attachment sites for several jaw, External occipital protuberance – bump on the back of the head; males have a
head, and neck muscles prominent, pointed one while females have a more subtle, rounded one
Facial bones – form the face; protect the entrances to the digestive and respiratory Sutural (wormian) bone – found within the lambdoid suture
systems; provide attachment sites for facial muscles LATERAL VIEW – shows 1 parietal bone, 1 temporal bone, 1 zygomatic bone, 1
Cranial cavity – encloses, cushions, and supports the brain maxilla, frontal bone, mandible, and portions of the occipital bone
ANTERIOR VIEW – shows the major bones of the skull Lacrimal bone – articulates w/ the nasal bone anteriorly and w/ the ethmoid bone
Frontal bone – forms the forehead posteriorly
Orbital cavity – eye sockets; Sphenoid bone- articulates w/ the frontal, parietal, and temporal bones
Superior and Inferior orbital fissure - 2 large openings Pterion – region that represents the H-shaped set of sutures of these 4 articulating
Superciliary arches – brow ridges; superior to the orbits bones
Nasal bones – left and right; form the bony bridge of the nose Zygomatic bone – cheekbone; forms the zygomatic arch
Glabella – superior to the nasal bones, found b/w the orbits Zygomatic arch – bones posterior to your ears; terminates superior to the point
Maxillae – left and right fuse to form most of the upper jaw and the lateral where the mandible articulates w/ the mandibular fossa of the temporal bone
boundaries of the nasal cavity; help form the floor of each orbit Mastoid process – posterior to the external auditory canal; the bump you feel
Infraorbital foramen – inferior to each orbit, within each maxilla; conducts blood posterior and inferior to your external ear opening
vessels and nerves to the face SAGGITAL VIEW – reveals bones that form the nasal cavity and the endocranium;
Mandible –forms the lower jaw shows bones that form the nasal septum more clearly
Mental protuberance – prominent chin of the mandible Frontal sinus – space in the frontal bone
Anterior nasal spine – found on the inferior border Sphenoidal sinus – open space in the sphenoid bone
,Perpendicular plate – forms the superior portion of the nasal septum Occipitomastoid suture – connects the occipital bone w/ the portion of the
Vomer – forms the inferior portion temporal bone that houses the mastoid process
Ethmoid bone – serves as a “wall” b/w the anterior floor of the cranial cavity and Coronal suture – extends across the superior surface of the skull along a coronal or
the roof of the nasal cavity frontal plane; represents the articulation b/w the anterior frontal bone and the
Maxillae and palatine bones – form the hard palate; acts as both the floor of the more posterior frontal bone
nasal cavity and part of the roof of the mouth Lamdboid suture – extends like an arc across the posterior surface of the skull,
INFERIOR (BASAL) VIEW - shows that the skull is a bit complex bec of its foramina articulating w/ the parietal bones and the occipital bone; named for the Greek
and weird-shaped bone features letter lambda, w/c its shape resembles (λ)
Hard palate – most anterior structure Saggital suture – extends b/w the superior midlines of the coronal and the lambdoid
Pterygoid processes of the sphenoid bone – found on either side of the palate sutures; in the midline of the cranium (along the midsaggital plane) and articulates
Internal nares – adjacent to these openings; internal openings of the nasal cavity the right and left parietal bones
Foramina – found b/w the mandibular fossa and pterygoid processes Squamosal suture – found on each side of the skull; articulates the temporal bone
Foramen ovale – closest to the pterygoid processes and the parietal bone of that side; squamous part of the temporal bone typically
Foramen spinosum – lateral to the pterygoid processes overlaps the parietal bone
Jugular foramen – posterior and lateral to these foramina; space b/w the temporal Sutural bones – wormian bones; small; ranging in size from a tiny pebble to a
and the occipital bones; anteromedial to this is the entrance to the carotid canal quarter but can also be larger; any suture may have sutural bones but are most
Foramen lacerum – extends b/w the occipital and temporal bones; this opening is common in lambdoid suture; represent independent bone ossification centers
closed off by connective tissue in a living individual BONES OF THE CRANIUM (8 bones)
Foramen magnum – largest foramen of all; means big hole; through this opening, form a rigid protective structure for the brain
spinal cord enters the cranial cavity and becomes continuous with the brain stem; CRANIUM – consists of a roof and a base
on either side are the rounded occipital condyles Calvaria – skullcap; roof of the cranium; composed of the squamous part of
INTERNAL VIEW OF CRANIAL BASE – reveals the following: the frontal bone, the parietal bones , squamous part of the occipital bone
Frontal bone – most anteriorly located bone Base – composed of portions of the ethmoid, sphenoid, occipital, temporal
Cribriform plate of the ethmoid bone – surrounded by the frtonal bone Cranial Bones – form as a result of the fusion of separate ossification
Lesser & greater wings of the sphenoid – found posterior to the frontal bone centers, an event that may not occur until after birth
Temporal bones – form the lateral regions of the cranial base FRONTAL BONES – form part of the calvaria, the forehead, roof of the orbits;
Occipital bone – form the posterior aspect formed from 2 major separate ossification centers; orbital surface is relatively
SUTURES smooth
immovable fibrous joints that form the boundaries b/w the cranial bones; dense ▪ Metopic suture – unites the left and right sides of the developing frontal bone;
regular connective tissue seals cranial bones firmly together at a suture; different this suture usually fuses and disappears by age 2
types of sutures are distinguished by the margins b/w the bones, w/c often have ▪ Frontal squama – vertical flattened region of the frontal bone; ends at the
intricate interlocking forms, like puzzle pieces, and form a strong union, or supraorbital margins
articulation; typically disappear as the adjoining bones fuse ▪ Superciliary arches – superior to the supraorbital margins; brow ridges; male
Endocranially – when fusion of bones starts internally skulls have more pronounced arches than female skulls
Ectocranially – fusion of the skull’s external surface ▪ Supraorbital foramen / notch – found at the midpoint of each supraorbital
Osteologists can estimate the approximate age at death of an individual skull by margin
examining the extent of suture closure. ▪ Glabella – smooth part of the frontal bone sandwiched b/w the superciliary
arches
, ▪ Frontal sinuses – found within the frontal bone; start to appear after age 6 and o Stylomastoid foramen- lies b/w the mastoid process and the styloid
develops fully at age 10 process; facial nerve extends through here to innervate the facial
▪ Frontal crest – found on the internal surface of the frontal bone; a midline muscles
elevation of bone; serves as a point of attachment for the falx cerebri o Carotid canal – medial to the styloid process; transmits the internal
▪ Falx cerebri – protective connective tissue sheet that helps support the brain carotid artery
PARIETAL BONES – form the lateral walls and roof of the cranium; its internal ▪ Squamous region – lateral flat surface of the temporal bone immediately
surfaces exhibit many grooves that accommodate some of the blood vessels w/n inferior to the squamosal suture
the cranium; each parietal bone is bordered by 4 sutures that unite it to the o Zygomatic process – inferior to the squama; curves laterally and
neighboring bones anteriorly to unite w/ the temporal process of the zygomatic bone;
▪ Parietal foramen – occurs in the posterior 1/3 of the parietal bone, adjacent to this union forms the zygomatic arch
the saggital suture; a tiny emissary vein travels through this opening, o Mandibular fossa – a depression where each temporal bone
connecting the venous sinuses w/ the veins of the scalp articulates w/ the mandible inferior to the base of both zygomatic
▪ Superior & inferior temporal lines – found on the lateral surface; a pair of faint processes
ridges exhibited on each parietal bone; arc cross the surface of the parietal and o Articular tubercle – a bump anterior to the mandibular fossa
frontal bones; mark the attachment site of the large, fan-shaped temporalis o Tympanic region – immediately posteriolateral to the mandibular
muscle that closes the mouth fossa; small bony ring surrounding the entrance to the external
▪ Parietal eminence – superior to the temporal lines; rounded, smooth parietal auditory canal
surface OCCIPITAL BONES – its concave internal surface closely follows the
TEMPORAL BONES – form the inferior lateral walls and part of the floor of the contours of the brainsubdivided into:
cranium; each temporal bone is composed of 3 regions: ▪ Squamous region – forms the posterior region of the skull
▪ Petrous region – means rock; thick region; houses sensory structures of the ▪ Basilar region – forms part of the base of the cranium
inner ear that provide info about hearing and balance o Foramen magnum – large, circular opening
o Internal auditory canal – also called auditory meatus or acoustic o Occipital condyles – found lateral to this foramen; smooth
meatus; provides a passageway for nerves and blood vessels to the knobs; where the skull articulates w/ the first cervical
inner ear vertebra (i.e. when you nod yes, you are moving the occipital
o Groove for the sigmoid sinus – runs along the inferior surface of the condyles against the vertebra)
petrous region o Hypoglossal canal – found at the anteromedial edge of each
o Sigmoid sinus - venous sinus (vein) that drains blood from the brain condyle; where the hypoglossal nerve extends to supply
o Mastoid process – prominent bulge on the inferior surface of the tongue muscles
temporal bone; anchoring site for muscles that flex or rotate the head; o Condylar canal – found posterior to each occipital condyle;
filled w/ many small, interconnected air cells that communicate w/ the transmits a vein
middle ear ▪ Prominent ridges that appear on the external surface of the occipital
o Mastoid foramen – found on the inferior surface of the temporal bone:
bone; opens near the mastoid process; tiny emissary veins travel o External occipital crest – projects in a posterior direction from
through this foramen to connect the venous sinuses inside the the foramen magnum, ending in the external occipital
cranium w/ the veins on the scalp protuberance
o Styloid process – serves as an attachment site for several hyoid and
tongue muscles
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller gaddielmatira. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
64438 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now