The Axial Skeleton Flashcards
What makes up the Axial Skeleton?
Skull, vertebral column, and bony thorax
What are the three subgroups of the skull?
Cranium, facial bones, and associated bones (hyoid bone and ear ossicles)
Function of the cranium
Enclose and protect the fragile brain tissue
Function of the facial bones
Support the eyes and position them anteriorly. Also provide attachment sites for facial muscles.
Frontal bone
Anterior portion of cranium; forms the forehead, superior part of the orbit, and floor of anterior cranial fossa
Parietal bones
Posterolateral to the frontal bone, forming sides of cranium
Temporal bones
Inferior to parietal bone on lateral skull. 3 parts: Squamous, tympanic, and petrous
Sagittal suture
Midline articulation point of the two parietal bones
Coronal suture
Point of articulation of parietals with frontal bone
Squamous suture
Point of articulation of the temporal bone with the parietal bone
Zygomatic process
Bridgelike projection joining the zygomatic bone (cheekbone) anteriorly.
Mandibular Fossa
Rounded depression on the inferior surface of the zygomatic process (anterior to the ear); forms the socket for the condylar process of the mandible, where the mandible joins the cranium
External acoustic meatus
Canal leading to eardrum and middle ear
Styloid Process
Needlelike projection inferior to external acoustic meatus; attachment point for muscles and ligaments of the neck.
Zygomatic Arch
Zygomatic bone and zygomatic process
Mastoid Process
Rough projection inferior and posterior to external acoustic meatus; attachment site for muscles.
Occipital bone
Most posterior bone of cranium - forms floor and back wall. Joins sphenoid bone anteriorly via its narrow basilar part.
Foramen Magnum
Large opening in base of occipital, which allows the spinal cord to join with the brain
Occipital Condyles
Rounded projections lateral to the foramen magnum that articulate with the first cervical vertebra (atlas)
Sphenoid bone
Bat-shaped bone forming the anterior plateau of the middle cranial fossa across the width of the skull. Is the keystone of the cranium because it articulates with all other cranial bones.
Greater wings of Sphenoid
Portions of the sphenoid seen exteriorly anterior to the temporal and forming a part of the eye orbits
Sella Turcica
A saddle-shaped region in the sphenoid midline. Hypophyseal fossa surrounds pituitary gland (hypophysis)
Lesser wings of Sphenoid
Bat-shaped portions of the sphenoid anterior to the sella turcica
Optic Canal (optic foramen)
Openings int he bases of the lesser wings through which the optic nerves (cranial nerve II) enter the orbits to serve the eyes.
Ethmoid Bone
Irregularly shaped bone anterior to the sphenoid. Forms the roof of the nasal cavity, upper nasal septum, and part of the medial orbit walls.
Crista galli
Vertical projection providing a point of attachment for the dura mater, helping to secure the brain within the skull
Cribriform plates
Bony plates lateral to the crista gallithrough which olfactory fibers (cranial nerve I) pass to the brain from the nasal mucosal through the cribriform foramina.
Mandible
The lower jawbone, which articulates with the temporal bones in the only freely movable joints of the skull
Condylar head (process)
Articulation point of the mandible with the mandibular fossa of the temporal bone
Mental foramen
Prominent opening on the body (lateral to the midline) that transmits the mental blood vessels and nerve to the lower jaw
Mandibular foramen
On the medial aspect of the mandibular rams. Foramen permits passage of the nerve involved with tooth sensation (mandibular branch of cranial nerve V)
Maxilla
Two bones fused in a median suture; form the upper jawbone and part of the orbits. All facial bones, except mandible, join the maxilla.
Palatine process
Form the anterior hard palate; meet medially in the inter maxillary suture
Palatine bones
Paired bones posterior to the palatine processes; form posterior hard palate and part of the orbit; meet medially at the median palatine suture
Zygomatic bones
Lateral to the maxilla; forms the portion of the face commonly called the cheekbone, and forms part of the lateral orbit. Its three processes are named for the bones with which they articulate
Lacrimal bones
Fingernail-sized bones forming a part of the medial orbit walls between the maxilla and the ethmoid. Each lacrimal bone is pierced by an opening, the lacrimal fossa, which serves as a passageway for tears.
Nasal bones
Small rectangular bones forming the bridge of the nose
Vomer
Blade-shaped bone in median plane of nasal cavity that forms the posterior and inferior nasal septum
Inferior nasal conchae
Thin curved bones protruding medially from the lateral walls of the nasal cavity; serve the same purpose as the turbinate portions of the ethmoid bone.
What are the paranasal sinuses?
Frontal sinus, ethmoid air cells, sphenoidal sinus, and maxillary sinus
Hyoid bone
Located in the throat above the larynx. Serves as a point of attachment for many tongue and neck muscles. Does not articulate with any other bone.
Lambdoid suture
Site of articulation of occipital bone and parietal bone
Vertebral column function
Forms the body’s major axial support. Surrounds and protects the spinal cord while allowing spinal nerves to emerge.
Body (Centrum) of vertebra
Rounded central portion of the vertebra, which faces anteriorly in the human vertebral column
Vertebral arch
Composed of pedicles, laminae, and a spinous process, it represents the junction of all posterior extensions from the vertebral body
Vertebral foramen
Opening enclosed by the body and vertebral arch; a passageway for the spinal cord
Transverse processes
Two lateral projections from the vertebral arch
Spinous process
Single medial and posterior projection from the vertebral arch
Superior and inferior articular processes
Paired projections lateral to the vertebral foramen that enable articulation with adjacent vertebrae. The superior articular process typically face toward the spinous process (posteriorly), whereas the inferior articular processes face (anteriorly) away from the spinous process.
Intervertebral foramina
The right and left pedicles have notches on their inferior and superior suffices that create openings, the intervertebral foramen, for spinal nerves to leave the spinal cord between adjacent vertebrae
Intervertebral disc
A pad of fibrocartilage that cushions the vertebrae and absorbs shock.
5 division of the vertebral column
Cervical, thoracic, lumbar, sacrum, and coccyx
Number of cervical vertebrae
7
Number of thoracic vertebrae
12
Number of lumbar vertebrae
5
Number of sacral vertebrae
5
Number of coccygeal vertebrae
Usually 4
