The Axial Skeleton - Anatomy and Physiology - Laboratory Flashcards
forms the longitudinal axis of the body
axial skeleton
axial skeleton is composed of
80 bones
axial skeleton is composed of 80 bones including the
skull, vertebral column, and thoracic cage
Functions of Axial Skeleton
- provides a strong structural support column for the body.
- encase major organs, including the brain, spinal cord, lungs, and heart and provide protection for these soft tissues.
protects the delicate brain, provides attachment sites for head and neck muscles, and houses the major sensory organs for vision, hearing, balance, taste, and smell.
skull
functions of skull
- protects the delicate brain, provides attachment sites for head and neck muscles
- houses the major sensory organs for vision, hearing, balance, taste, and smell.
The skull and associated bones total
29 bones:
- 22 skull bones (8 cranial bones and 14 facial bones)
- 6 auditory ossicles
- the hyoid bone
22 skull bones is composed of
8 cranial bones and 14 facial bones
the hyoid bone discussed with the skull because of its
proximity
supports the trunk, protects the spinal cord, and provides attachment sites for the ribs and for the muscles of the neck and back.
Vertebral Column
In fetuses and infants, the vertebral column consists of
33 separate vertebrae
adults have only _____________ because ___________ of these bones eventually fuse to form two composite bones—the sacrum and coccyx.
26 vertebral bones; nine
In fetuses and infants, the vertebral column consists of 33 separate vertebrae. However, adults have only 26 vertebral bones because nine of these bones eventually fuse to form two composite bones—the ____________________________
sacrum and coccyx
forms a protective structure around the organs of the thoracic cavity.
Thoracic Cage (rib cage)
other term for thoracic cage
rib cage
Thoracic Cage (rib cage) consists of
sternum and the paired ribs (a total of 25 bones), the costal cartilages, and the thoracic vertebrae of the vertebral column.
eight bones that form the cranium
Cranial Bones
Cranial Bones are connected by immovable articulations called
sutures
The cranium can be divided into two major areas:
- cranial vault
- cranial base
- forms the superior, lateral, and posterior walls of the skull
Cranial Vault (calvarium)
other term for cranial vault
calvarium
- forms the bottom of the skull
Cranial Base (cranial floor)
other term for cranial base
cranial floor
The cranial base has three distinct depressions:
anterior, middle, and posterior cranial fossae.
how many are the facial bones
14
- form the framework for the face, anchor the facial muscles, secure the teeth, and house special sense organs for vision, taste, and smell.
facial bones
- All of the facial bones are joined by __________ (except for the mandible, which is joined to the cranium by a freely movable joint).
sutures
- All of the facial bones are joined by sutures (except for the _____________, which is joined to the cranium by a freely movable joint).
mandible
forms the anterior portion of the cranium.
Frontal Bone
Features of the frontal bone include:
- frontal squama (forehead)
- supraorbital foramen (notch)
- glabella
other term for frontal squama
forehead
othe rterm for supraorbital foramen
notch
- an opening above each orbit that serves as a passageway for blood vessels and nerves
Supraorbital Foramen (notch)
- the smooth area between the eyes
Glabella
- form the superior portion and part of the lateral walls of the cranium
Parietal Bones
- connects the two parietal bones
Sagittal Suture
- connects the parietal bones to the frontal bone
Coronal Suture
- connects the temporal bone with the parietal bone
Squamous Suture
- connects the occipital bone to the parietal bones
Lambdoid Suture
- connects the temporal bone (near the mastoid process) to the occipital bone
Occipitomastoid Suture
- form part of the lateral walls of the cranium inferior to the parietal bones
Temporal Bones
Temporal Bones are divided into the
squamous, tympanic, mastoid, and petrous regions
- house a total of six tiny bones called auditory ossicles, which function in the special sense of hearing.
Temporal Bones
Temporal Bones house a total of six tiny bones called
auditory ossicles
function in the special sense of hearing
auditory ossicles
- One important bone marking of the squamous region of the temporal bone
Zygomatic Process
- a bar-like structure that projects anteriorly to articulate with the zygomatic bone
Zygomatic Process
along with the temporal process of the zygomatic bone, it forms the zygomatic arch (cheekbone)
Zygomatic Process
Zygomatic Process along with the temporal process of the zygomatic bone, it forms the
zygomatic arch (cheekbone)
other term for zygomatic arch
cheekbone
- another bone marking of the temporal bone
- a depression where the mandibular condyle of the mandible articulates with the temporal bone
Mandibular Fossa
Important bone markings of the tympanic region of the temporal bone include the:
- external acoustic meatus
- styloid process
- conducts sound waves toward the eardrum
External Acoustic Meatus
- a sharp projection that serves as the attachment site for some muscles of the tongue and pharynx
styloid process
- is also the attachment site for the ligament that anchors the hyoid bone to the skull
styloid process
- in the mastoid region
- a prominent projection that serves as an attachment site for some neck muscles
mastoid process
Important bone markings of the petrous region of the temporal bone include the:
- jugular foramen
- carotid canal
- foramen lacerum
- internal acoustic meatus
- a passageway for three cranial nerves and for the internal jugular vein, which drains blood from the brain
Jugular Foramen
- drains blood from the brain
Internal Jugular Vein
- a passageway for the internal carotid artery, which delivers blood to the brain
Carotid Canal
- delivers blood to the brain
Internal Carotid Artery
- a jagged opening that serves as a passageway for small arteries supplying blood to the inner surface of the cranium
Foramen Lacerum
- a passageway for two cranial nerves.
Internal Acoustic Meatus
- In a living person, the foramen lacerum is mostly filled with
hyaline cartilage
- forms the posterior part and most of the base of the cranium
Occipital Bone
- is a large opening on the inferior surface of the skull where the brain and spinal cord meet
Foramen Magnum
- are rounded projections that articulate with the first cervical vertebra (atlas) to form the atlanto-occipital joint, which allows you to nod “yes.”
Occipital Condyles
Occipital Condyles are rounded projections that articulate with the first cervical vertebra (atlas) to form the _____________________
atlanto-occipital joint
atlanto-occipital joint
allows you to nod “yes.”
- are openings through which a cranial nerve pass
Hypoglossal Canals
- is a ridge of bone that extends posteriorly from the foramen magnum and ends at the external occipital protuberance
External Occipital Crest
- is a small, mid-line bump at the end of the external occipital crest
External Occipital Protuberance
- it occurs at the junction between the base and the posterior wall of the skull
External Occipital Protuberance
- are small transverse ridges on either side of the external occipital protuberance
Superior and Inferior Nuchal Lines
- they are created by neck muscle attachments
Superior and Inferior Nuchal Lines
- a bat-shaped bone located posterior to the frontal bone, articulates with every other cranial bone
Sphenoid Bone
- project laterally from the central body of the sphenoid bone and form part of the floor of the middle cranial fossa
Greater Wings
- are horn-shaped projections that form part of the floor of the anterior cranial fossa
Lesser Wings
- project inferiorly from the greater wings and serve as attachment sites for muscles
Pterygoid Processes
- a long, slit-like opening between the greater and lesser wings, is a passageway for three cranial nerves
Superior Orbital Fissure
- is a saddle-shaped area in the midline of the sphenoid bone containing the hypophyseal fossa (the seat of the saddle), which houses the pituitary gland (also called the hypophysis).
Sella Turcica
- are openings at the base of the lesser wings that serve as passageways for the optic nerves
Optic Canals
Optic Canals six openings—
- the oval-shaped FORAMINA OVALE posterior to the sella turcica
- the round FORAMINA ROTUNDUM lateral to the sella turcica
- the small FORAMINA SPINOSUM lateral to the foramina ovale
- serve as passageways for another cranial nerve and an artery
Optic Canals
- is the most deeply situated bone of the skull
Ethmoid Bone
- a superior projection in the midline of the ethmoid bone
Crista Galli
- is attached to the brain by connective tissue wrappings and helps secure the brain within the cranial cavity
Crista Galli
- located on either side of the crista galli
Cribriform Plates
- bony plates studded with olfactory foramina that serve as passageways for fibers of the olfactory cranial nerves
Cribriform Plates
- forms the superior portion of the nasal septum
Perpendicular Plate
- are thin scrolls of bone that project into the nasal cavity on either side of the perpendicular plate
Superior and Middle Nasal Conchae
- they create air turbulence that slows air movement, warms and moistens inhaled air, and removes dust before the air reaches the delicate tissues of the lower respiratory tract.
Superior and Middle Nasal Conchae
other term for Superior and Middle Nasal Conchae
turbinates
- articulates with the temporal bones at the mandibular fossae to form the only freely movable joints of the skull
Mandible
other term form Mandible
lower jawbone
- is the horizontal part of the bone that forms the inferior jawline (chin) and anchors the lower teeth.
Body of the Mandible (Mandibular Body)
- the superior border of the mandibular body, contains the tooth sockets
Alveolar Process
- are openings in the mandible that serve as passageways for nerves and blood vessels supplying the lips and chin.
Mental Foramina
- is an upright “branch” of the mandible that serves as the attachment site for a muscle that assists in elevating (closing) the jaw
Mandibular Ramus
- is the area at which the body meets the ramus
Mandibular Angle
- is a rounded projection that articulates with the mandibular fossa of the temporal bone to form the temporomandibular joint (TMJ)
Mandibular Condyle
Mandibular Condyle is a rounded projection that articulates with the mandibular fossa of the temporal bone to form the
temporomandibular joint (TMJ)
- is the insertion site for a muscle that closes the mouth.
Coronoid Process
- is the indentation between the coronoid process and the mandibular condyle
Mandibular Notch
- form the upper jawbone
Maxillae
Maxillae are considered the
“keystone bones”
- are considered the “keystone bones” of the face because they articulate with all other facial bones except the mandible.
Maxillae
- inferior border of the bones
- contains the tooth sockets
Alveolar Process
- project medially from the alveolar margin to form the anterior portion of the hard palate (the bony roof of the mouth).
Palatine Processes
- an opening on the inferior midline of the palatine process, leads into the incisive canal, which contains blood vessels and nerves
Incisive Fossa
- an opening below the orbit, and the inferior orbital fissure
Infraorbital Foramen
- a slit-like opening in the floor of the orbit, provide passageways for blood vessels and nerves
Infraorbital Foramen
- the smallest bones in the skull, are located in the medial portion of each orbit
Lacrimal Bones
- a deep groove
- contains a lacrimal sac
Lacrimal Fossa
- collects tears and drains the fluid into the nasal cavity
Lacrimal Sac
of the zygomatic bones) plus the zygomatic processes of the temporal bones form the zygomatic arches, which form the lateral rims of the orbits
temporal processes
- form the bridge of the nose
Nasal Bones
- forms the inferior portion of the nasal septum
Vomer Bone
- Posterior to the palatine processes of the maxillae
Palatine Bones
- which, with the palatine processes of the maxillae, form the hard palate (the bony roof of the mouth).
Palatine Bones
- are paired bones that project medially to form the lower, lateral walls of the nasal cavity.
Inferior Nasal Conchae (Turbinates)
- located in the frontal, ethmoid, sphenoid, and maxillary bones
Paranasal Sinuses
- are air-filled, mucus-lined cavities that connect with the nasal cavity.
Paranasal Sinuses
- They lighten the skull, add resonance to the voice, and warm, moisten, and clean inhaled air.
Paranasal Sinuses
The bones of the skull develop from _________________ in the developing embryo
fibrous membranes
At birth, ________________—commonly called “soft spots”—remain between the cranial bones.
fontanels
fontanels —commonly called ________________
“soft spots”
These unossified fibrous membranes allow the fetal skull to change shape as it passes through the birth canal and then permit brain growth during infancy.
fontanels
- the largest fontanel
Anterior Fontanel
- is diamond shaped and is located along the midline of the skull between the frontal bone and the two parietal bones
Anterior Fontanel
- usually closes 18–24 months after birth
Anterior Fontanel
- located along the midline between the two parietal bones and the occipital bone
Posterior Fontanel
- usually closes around 2 months after birth
Posterior Fontanel
- small, irregularly shaped
- are located between the frontal, parietal, temporal, and sphenoid bones
Sphenoid Fontanels
- they usually close around 3 months after birth
Sphenoid Fontanels
- are located between the parietal, occipital, and temporal bones
Mastoid Fontanels
- their complete closure occurs around 12 months after birth
Mastoid Fontanels
- divides the left and right frontal bones and closes completely at 3–9 month of age
Frontal Suture
- inferior to the mandible and is C-shaped
Hyoid Bone
- unique because it does not articulate with any other bone but instead is suspended from the styloid processes of the temporal bone by ligaments and muscles
Hyoid Bone
- serves as a moveable base for the tongue
Hyoid Bone
- horizontal part of hyoid bone
- is an attachment site for neck muscles that raise and lower the larynx during swallowing and speech.
Body
- attachment sites for other muscles and ligaments
Greater and Lesser Horns
- provides support for the head, neck, and trunk, and protection for the spinal cord
Vertebral Column
other term for vertebrae
- adult vertebral column, or spine
- a flexible chain of 26 bones
vertebrae
- Fibrocartilage pads
Intervertebral Discs
- cushion adjacent vertebrae (except the first two vertebrae, the atlas and the axis).
Intervertebral Discs
The bones of the vertebral column are grouped into five regions:
- cervical vertebrae (7)
- thoracic vertebrae (12)
- lumbar vertebrae (5)
- sacrum (1)
- coccyx (1)
When viewed from the side, the adult vertebral column exhibits
four normal curves
are concave posteriorly
cervical and lumbar curvatures
are convex posteriorly.
thoracic and sacral curvatures
A typical vertebra has a ____________________ (or centrum) that forms the vertebra’s anterior portion and bears the weight of superior structures.
rounded body
- a vertebra’s posterior portion
- composed of two pedicles and two laminae
Vertebral Arch
Vertebral Arch is composed of
two pedicles and two laminae
- connect the arch to the body
pedicles
- form the rest of the arch
laminae
- created by inferior sides of the pedicles curved superiorly
Inferior Vertebral Notch
- created by superior sides of the pedicles curved inferiorly
Superior Vertebral Notch
Each vertebral arch also has the following seven features:
- a spinous process
- two transverse processes
- two superior articular processes
- two inferior articular processes
a medial posterior projection that arises from the junction of the two laminae
spinous process
which project laterally from either side of the vertebral arch
transverse processes
which project superiorly from the pedicle-lamina junction and articulate with the inferior articular processes of the vertebra immediately superior to it at facets
superior articular processe
which project inferiorly from the pedicle-lamina junction and articulate with the superior articular processes of the vertebra immediately inferior to it at facets
inferior articular processes
- present in each vertebra
- an opening that lies between the body and the vertebral arch
Vertebral Foramen
- adjacent vertebral foramina form the vertebral canal, which houses the spinal cord
Vertebral Foramen
A typical cervical vertebra is characterized by:
1) an oval-shaped body
2) transverse foramina for the passage of the vertebral arteries, which supply blood to the brain, and of the vertebral veins, which drain blood from the brain
3) a bifid (forked) spinous process
4) a triangular vertebral foramen.
The first two cervical vertebrae:
- atlas (C1)
- axis (C2)
is named after Atlas, the mythical Greek god who carried the world on his shoulders.
Atlas (C1)
- is the only vertebra that articulates with the skull
Atlas (C1)
- lacks a vertebral body and has no spinous process
Atlas (C1)
- is essentially a ring of bone containing anterior arches that meet at the anterior tubercle and posterior arches that meet at the posterior tubercle, with lateral masses on either side
Atlas (C1)
- receive the occipital condyles of the occipital bone of the skull, and the inferior articular facets articulate with the axis, which is inferior to it.
Superior Articular Facets
- the joint between C1 and C2
Atlantoaxial Joint
- one of the axis’s unique features
- projects superiorly from the body
- articulates with the enlarged vertebral foramen of the atlas.
Dens (odontoid process)
other term for Dens
odontoid process
- most inferior cervical vertebra
- has a spinous process that is larger than those of other cervical vertebra, and it is not bifid
Vertebra Prominens (C7)
- it can be felt (palpated) through the skin
- is used as an anatomical landmark for counting the vertebrae
Vertebra Prominens (C7)
Each of the 12 thoracic vertebrae is characterized by:
1) a heart-shaped body bearing four (two inferior and two superior) small facets (costal facets), where a rib articulates with the vertebra
2) a spinous process that points sharply inferiorly
3) a circular vertebral foramen
The five lumbar vertebrae are characterized by having:
1) large sizes and weights
2) wide, kidney-shaped bodies;
3) blunt, hatchet-shaped spinous processes; and
4) triangular vertebral foramina
- is an irregular, wedge-shaped bone composed of five fused vertebrae that articulates with the fifth lumbar vertebra at the flattened base and superior articular processes, and with the coccyx at the apex
Sacrum
- articulate with the ilium of each coxal bone to form the posterior wall of the bony pelvis
Auricular Surfaces
- fusion of the sacral bones before birth consolidates the vertebral canal
Sacral Canal
the fifth sacral vertebra the sacral canal
Sacral Hiatus
- among the sacrum’s important bone markings
- through which sacral nerves pass
Sacral Foramina
- formed by the spinous processes of the five fused vertebrae
Median Sacral Crest
- provides attachment sites for muscles of the lower back and hip
Median Sacral Crest
- formed by the transverse processes of the five fused vertebrae
Lateral Sacral Crest
- provides attachment sites for muscles of the lower back and hip
Lateral Sacral Crest
- prominent bulge on the anterosuperior margin
Sacral Promontory
- is an important anatomical landmark in females during pelvic exams and during labor and delivery
Sacral Promontory
- On either side of the sacral promontory
Alae
- mark the sites of vertebral fusion
tranverse lines
- is composed of three to five fused vertebrae with hornlike projections, each called a coccygeal cornu.
coccyx
coccyx is composed of three to five fused vertebrae with hornlike projections, each called a
coccygeal cornu
- offers slight support to the pelvic organs and serves as a point of attachment for the muscles of the pelvic floor.
coccyx
- consists of the sternum, ribs, costal cartilages, and thoracic vertebrae
thoracic cage
thoracic cage or
ribcage
functions of thoracic cage or ribcage
1) forms a protective cage around the organs of the thoracic cavity
2) provides support for the pectoral (shoulder) girdle and the upper appendages
3) provides attachment sites for skeletal muscles of the neck, back, chest, and shoulders.
- a “dagger-shaped” bone located in the anterior midline of the thorax
sternum
thoracic cage or ribcage consists of
the sternum, ribs, costal cartilages, and thoracic vertebrae
Sternum is a composite bone resulting from the fusion of three bones:
- superior manubrium
- middle body
- inferior xiphoid process
Features of the sternum include
- suprasternal notch
- clavicular notch
- sternal angle
- xiphisternal joint
- is located medially at the level of the intervertebral disc between T2 and T3
Suprasternal Notch (or jugular notch)
other term for Suprasternal Notch
jugular notch
- where the clavicle forms a joint with the manubrium
Clavicular Notch
- a landmark for finding rib 2 when using a stethoscope to listen to heart sounds
Sternal Angle
- behind which the heart sits on the diaphragm
Xiphisternal Joint
- The wedge-shaped vertebral (medial) end of a rib bone
Head (Ribs)
- bulk of each rib
Shaft
The superior border of the shaft is smooth, whereas its inferior border is sharp and thin and contains a __________________, which houses intercostal nerves and blood vessels.
costal groove
- houses intercostal nerves and blood vessels.
costal groove
- the constricted area between the head and the shaft
(ribs)
- Each rib has two articular facets: one that articulates with a vertebral body and one that articulates with the vertebral transverse process.
Articular Facets
- the portion of a rib that is immediately lateral to the neck
Tubercle
- contains a facet that articulates with a transverse process of a thoracic vertebra
Tubercle
- is a bend where the shaft begins to curve toward the sternum
Angle
- Rib pairs 1–7
True Ribs (or vertebrosternal ribs)
other term for True Ribs
vertebrosternal ribs
- they attach to the sternum by their own cartilage
True Ribs (or vertebrosternal ribs)
- Rib pairs 8–12
False Ribs
- they either attach indirectly to the sternum (by way of cartilage immediately above each rib) or entirely lack a sternal attachment.
False Ribs
- rib pairs 8 through 10
Vertebrochondral Ribs
- rib pairs 11 and 12
Floating (or Vertebral) Ribs
