Lecture 15 - Skull and Vertebral column Flashcards
Axial skeleton
Bones along the midline
major structures includes - skull, vertebrae +discs, ribs + cartilages, sacrum, coccyx
Skull
Protection of the brain and brain stem
Protecting sensory organs
Imporatnt site of attachment for muscles and ligaments involved in speech, chewing, eye movement and facial expression
Joints of the skull =
sutures
sutures
Fibrous joint
Fused in late 20s
Membranous when young
Sutures of the skull
Coronal suture
Sagittal suture
Lamboid suture
Coronal suture
Seperates the front and parietal lobe
Fibrous joint
Sagittal suture
Seperates both parietals
Fibrous joint
Lamboid suture
seperates parietal and occipital bones
lamboid because it looks like the lambda sign
Fibrous joint
Squamous suture
Cranial sutures between the temporal and parietal bones bilaterally
extends posteriorly from the pterion
Pterion
region where the front, parietal, temporal and sphenoid bones join together
located on the side of the skull, just behind the temple
weak part of the skull because all the bones meet here therefore it is vunerable to injury
Anterior fontanelle
Diamond shaped membrane-filled space located between the two frontal and two parietal bones of the developing fetal skull
it is at the junction of the coronal suture and sagittal suture
more like a membrane but as a baby grows it starts to ossify
Posterior fontanelle
The junction of the two parietal bones and the occipital bone
this one usually closes first
fetal skull feature that ossifies as a baby grows
Temporal line
it is where the muscle attaches to (temporalis)
on both sides of the skull
TMJ stands for
temporomandibular joint
TMJ
Temporomandibular joint
Synovial joint
Movements = protrusion, retraction, elevation and depression
Mandible features
It attaches to the temporal bone via the TMJ
It is a site for muscle attachments (e.g., for chewing, facial expressions)
It has alveolar process for teeth
Alveolar process
thickened ridge of bone that containes the tooth sockets on the jaw bones that hold teeth
Condylar process of mandible
thicker than coronoid process
condyler processes articulate with the temporal bone to create the TMJ which permits mobility
(posterior to the coronoid process)
Coronoid process of mandible
Located on the superior aspect of the ramus
the temporalis muscle attaches here on its lateral surface, helps closing of the mouth
(in front of the condyler process)
Alveolar arch
curved border formed by the free border of the alveolar process
Other general features of the mandible
Ramus
Angle
Body
Mental foramen
one of two formina located on the anterior surface of the mandible
transmits the mental nerve
formamen =
opening
skull is made up of
viscerocranium
neurocranium
neurocranium
(vault)
protects the brain and consists of ... Singular bones (frontal, ethmoidal, sphenoidal, occipital) Paired bones (temporal, parietal)
viscerocranium
consists of the facial skeleton
Singular bones (mandible, ethmoid, vomer) Paired bones (maxillae, zygomatic, palatine, nasal, lacrimal, inferior nasal conchae)
Viscerocranium -singular bones
mandible, ethmoid, vomer
Viscerocranium - paired bones
maxillae, zygomatic, palatine, nasal, lacrimal,
inferior nasal conchae
Neurocranium - singular bones
frontal, ethmoidal, sphenoidal, occipital
Neurocranium - paired bones
temporal, parietal
Vomer
singlular bone of the viscerocranium
small thin bone that seperates the right and left nasal cavities
Ethmoid bone
square bone at the root of the nose and has many perforations through which the olfactory nerves pass to the nose
Upper jaw =
maxilla
Lower jaw =
mandible
Maxilla
has maxillary process
bone that forms the upper jaw
the right and left are irregular shaped bones and fuse together in the middle of the skull
reduce the heaviness of the skull, help support the back teeth, and help to allow the voice to resonate
paired bone of viscerocranium
Zygomatic bone
its main function is to provide structure and strength to the mid-face.
the cheek bones
projections called the frontal processes
paired bone of viscerocranium
Nasal bone
The nasal bones are two small, symmetrical midface bones of the skull which build the bridge of the nose.
paired bone of viscerocranium
Inferior nasal conchae
one of the three paired nasal conchae in the nose
increase the surface area of the nasal cavity – this increases the amount of inspired air that can come into contact with the cavity walls.
paired bone of viscerocranium
lacrimal (location)
a small bone forming part of the eye socket.
paired bone of viscerocranium
Supraorbital notch (foramen)
Above eye sockets
Allows passage of supraorbital nerve that provides sensation of forehead skin
Mastoid process
process on the mastoid area of the temporal bone
attachment for neck muscles
Styloid process
slender pointed piece of bone just below the ear
Zygomatic process of the temporal bone
extension of the temporal bone
Frontal bone
Forms the anterior and superior walls
Articulates with other bones via sutures
coronal suture seperates frontal bone from parietal bones
features of the frontal bone
Supraorbital notch/foramen - contains supraorbital
vein, artery, nerve
Supraorbital ridge
- on top of eyebrows
supraorbital = situated above the orbit of the eye
Parietal bones
Form the lateral and superior walls
Has temporal lines for temporalis muscle
Contribute to pterion
(a weak part of the skull)
Each temporal bone has …
a mandibular fossa for TMJ
mastoid and styloid processes
zygomatic process
internal and external acoustic meatus
Tympanic part of the temporal bone
curved process immediarely below the origin of the zygomatic process
encloses part of the middle ear
External acoustic meatus
is a bony canal for the ear canal
Features of occipital bone
forms posterior and floor of vault
occipital protuberance (for muscle and ligament attachment)
Occipital condyles (for C1 articulation)
Foramen magnum (for spinal cord)
Occipital condyles
for C1 articulation therefore in effect attaches the head to the body
rounded projection
Foramen magnum
Hole for the spinal cord
External occipital protuberance
For muscle and ligament attachment
Males have a more prominent one
Sphenoid bone
Unpaired bone of the neurocranium
situated in the middle of the skull up towards the front
lesser and greater wing
hyperphyseal fossa for pituitary gland
Features of the sphenoid bone
Has greater and lesser wings
Has hypophyseal fossa (for pituitary gland)
Has many foramina for nerves and blood vessels
Has pterygoid processes for muscles attachent
Pterygoid processes
muscle attachment
Hyperphysial fossa
for pituitary
fossa =
depression or hollow
Ethmoid bone features
Has cribriform plate (has perforations for olfactory nerves) (to prevent going into the nasal cavity)
Crista galli, an attachment site for the dura ( layer of the brain, dura mater)
Ethmoidal air sinuses (empty space within bone, blockage can cause infection)
Base of skull has …
Anterior cranial fossa
Middle cranial fossae
Hypophyseal fossa
Posterior cranial fossa
Functions of the vertebral column
Protecting spinal cord and spinal nerves
Keep the torso upright and attachment to pelvic girdle for bipedalism
Attachment sites for muscles and ligaments
Cervical number
7
Thoracic number
12
Lumbar number
5
Sacral number
5 and they fuse into 1 when you get older
Coccyx
3-4
Mobile vertebrae
Cervical (7)
Thoracic (12)
Lumbar (5)
Fused vertebrae
Sacral (5)
Coccygeal (3-4)
Typical vertebrae features (lumbar)
Body Pedicle Transverse process Lamina Spinous process Articular processes
Pedicle
The pedicle lies between the back of the vertebral body and the transverse process
there are two pedicles per vertebrae (one on each side)
Connects body to vertebral arch
Lamina
The laminae, flattened plates that fuse in the median plane, complete the arch posteriorly.
Transverse process
Small bony projection off the right and left of each vertebrae
function as a site of attachment for muscles and ligaments of the spine as well as the point of articulation of the ribs (in the thoracic spine)
Spinous process
bony projection off the posterior of each vertebrae
protrudes where the laminae of the vertebral arch join and provides the point of attachment for muscles and ligaments of the spine
Articular process
projections of the vertebra that serve the purpose of fitting with an adjacent vertebrae
the actual region of contact is called the articular facet
Cervical vertebrae features
Small body
Bifurcated spinous process (for nuchal ligament attachment although it is not the point of origin or insertion)
Transverse foramina for vertebral artery (foramen transversarium) (on transverse process)
C1 (Atlas) and C2 (Axis) are specialized
Cervical - anterior tubercle
thickening of bone
Cervical - facet for occipital condyle
forms part of the atlantooccipital joint which is important for nodding motion
Cervical - spinous process
Bifurcated spinous process - split into 2, for ligament
Cervical - Axis (CII)
Dens - comes in contact with facet for dens on the atlas (C1)
Atlantoaxial joint - for shaking head side to side/for neck rotation (between C1 and C2)
Features of thoracic vertebrae
Spinous process points downward
Has costal facets for rib attachment: superior, inferior, transverse
Little movement between two adjacent vertebrae
Multiple thoracic vertebrae allow more movements
demifacet for articularion with head of its own rib, demifacet for articulation with head of rib below (another rib)
Lumbar vertebrae features
Large body for load bearing (transmit force from upper body)
Do not allow much movement (not very mobile, needs to support the body, holds weight from the top of the body)
Distal end of the spinal cord ends at L1/L2 (spinal cord ends at L1/L2)
Only cauda equina below this level; important site for lumbar puncture
Sacrum features
5 fused vertebrae
Forms the sacroiliac joint with the pelvis
It has sacral canal (superior, inferior extension of vertebral canal (foramen( and contains the sacral coccygeal spinal nerves, which descend from the end of the spinal cord at L1 as part of the cauda equina), sacral hiatus (inferior, gap at the lower end of the sacrum, exposing the vertebral canal)
Sacral cornua
Comes into contact with coccyx at coccygeal cornu
Sacral coccygeal symphysis
has disc
fibrocartilage
Coccyx
The number varies between people
“vestigial tail” in human
Forms the sacrococcygeal symphysis
Easily fractured, deteriorates with age
Joints of the vertebral column
Zygapophyseal joint is a synovial joint between superior and inferior articular processes of adjacent vertebrae
It forms the invertebral foramen, for spinal nerve
Intervertebral discs are found
between vertebrae, consisting of anulus fibrosus (fibrous structure) and nucleus pulposus (lots of water content which decreases with age) (there is also a layer of hyaline cartilage)
Intervertebral forament
for the spinal nerve
Zygapophysial (facet) joint
inferior articular process and superior articular process form this joint
Vertebral ligaments
Anterior and posterior longitudinal ligaments are located anterior and posterior to vertebral body
Ligamentum flavum (pl. flava) is located between adjacent lamina
Ligamentum nuchae extends from external occipital protuberance to C7; for posterior neck support
Supraspinous ligament connects the tip of spinous processes from C7 to sacrum
Interspinous ligament is between spinous processes
Anterior and posterior longitudinal ligaments
Anterior and posterior longitudinal ligaments are located anterior and posterior to vertebral body
along the length of the vertebrae, continuous
Ligamentum flavum (pl. flava)
Ligamentum flavum (pl. flava) is located between adjacent lamina
not continuous, multiple of them between two vertebrae
Ligamentum nuchae (nuchal ligament)
Ligamentum nuchae extends from external occipital protuberance to C7; for posterior neck support
large, triangular in shape
Supraspinous ligament
Supraspinous ligament connects the tip of spinous processes from C7 to sacrum
above spinous process
Interspinous ligament
Interspinous ligament is between spinous processes
Whiplash injury
Hyperextension of the neck
e.g. from rear-end collision, especially when the head rest is low
Anterior longitudinal ligament is stretched or torn.
“Teardrop” fracture and dislocation of vertebrae. Torn anterior longitudinal ligament.
