BIO210Y5 Chapter Notes - Chapter 8: Pterion, Coronal Suture, Inferior Nasal Concha

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18 Feb 2016
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Axial Movement – Bones and Joints
MODULE 7.1 – THE AXIAL SKELETON INCLUDES BONES OF THE HEAD, VERTEBRAL COLUMN, AND
TRUNK
The axial skeleton forms the longitudinal axis of the body
There are typically 80 bones in the axial skeleton
The axial skeleton provides a framework that supports and protects the brain, the spinal cord, an the
organs in the body cavities of the trunk
Also provides an extensive surface area for the attachment of muscles that…
oAdjust the position of the head, neck, and trunk
oPerform respiratory movements
oStabilize or position parts of the appendicular skeleton that support the limbs
The joints of the axial skeleton have limited movement, but they are very strong and heavily reinforced by
ligaments
MODULE 7.2 – THE SKULL HAS CRANIAL AND FACIAL COMPONENTS THAT ARE USUALLY BOUND
TOGETHER BY SUTURES
The skull contains 22 bones (8 from the cranium, 14 from the face)
7 additional bones are associated with the skull
Facial bones protect and support the entrances to the digestive and respiratory tracts; they also provide
areas for the attachment of muscles that control the facial expressions and assist in manipulating food
The cranial bones form the cranium, which encloses the cranial cavity, a fluid-filled chamber that
cushions and supports the brain
Blood vessels, nerves, and membranes that stabilize the position of the brain are attached to the inner
surface of the cranium; its outer surface provides an extensive area for the attachment of muscles that
move the eyes, jaws, and head
Joints, or articulations, form where two bones interconnect
The connections between the skull bones of adults are immovable joints called sutures
oAt a suture, bones are tied firmly together with dense fibrous connective tissue
The coronal suture attaches the frontal bone to the parietal bones of either side; the occipital, parietal,
and frontal bones form the roof of the skull, called the calvaria, or skullcap
A squamous suture on each side of the skull forms the boundary between the temporal bone and the
parietal bone of that side
The sagittal suture extends from the lambdoid suture to the coronal suture, between the parietal bones
The lambdoid suture arches across the posterior surface of the skull; this suture separates the occipital
bone from the two parietal bones; occasionally, one or more sutural bones (Wormian bones) may be
present along the lambdoid suture
MODULE 7.3 – FACIAL BONES DOMINATE THE ANTERIOR ASPECT OF THE SKULL, AND CRANIAL BONES
DOMINATE THE POSTERIOR SURFACE
FACIAL BONES CRANIAL BONES
1. The nasal bones support the superior portion of
the bridge of the nose. They are connected to
cartilages that support the distal portions of the nose.
2. The lacrimal bones form part of the medial wall of
the orbits (eye sockets).
3. The palatine bones form the posterior portion of
the hard palate and contribute to the floor of each
orbit.
4. The zygomatic bones contribute to the rim and
lateral wall of the orbit and form part of the
cheekbones.
5. The maxillae supports the upper teeth and form the
inferior orbital rim, the lateral margins of the external
nares, the upper jaw, and most of the hard palate.
1. The parietal bone on each side forms part of the
superior and lateral surfaces of the cranium
2. The frontal bone forms the anterior portion of the
cranium and the roof of the orbits. Mucus from the
frontal sinuses within this bone help flush the nasal
cavity surfaces.
3. The sphenoid bone forms part of the floor of the
cranium, unites the cranial and facial bones, and acts
as a cross-brace that strengthens the sides of the
skull.
4. The ethmoid bone forms the anteromedial floor of
the cranium, the roof of the nasal cavity, and part of
the nasal septum and medial orbital wall.
5. The occipital bone contributes to the posterior,
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6. The inferior nasal conchae create turbulence in
air passing through the nasal cavity, and increase the
epithelial surface area to warm and humidify inhaled
air.
7. The vomer forms the inferior portion of the bony
nasal septum.
8. The mandible forms the lower jaw.
lateral, and inferior surfaces of the cranium.
6.The temporal bone on either side (1) forms part of
the lateral wall of the cranium and articulates with
facial bones, (2) forms an articulation with the
mandible, (3) surrounds and protect the sense organs
of the internal ear, and (4) is an attachment site for
muscles that close the jaws and move the head.
7.8 – THE MANDIBLE FORMS THE LOWER JAW, AND THE ASSOCIATED BONES OF THE SKULL PERFORM
SPECIALIZED FUNCTIONS
The mandible forms the entire lower jaw and articulates with the mandibular fossae of the temporal bones
Coronoid Process the insertion point for the temporalis muscle, a
powerful muscle that closes the jaws
Ramus
the ascending part that begins at the mandibular
angle on either side; the masseter muscle, which is
involved with chewing, is attached on its lateral
surface
Condylar Process articulates with the temporal bone at the
temporomandibular joint
The hyoid bone one of the seven associates bones of the skull supports the larynx and is the
attachment site for muscles of the larynx, pharynx, and tongue
Also associated with the skull are six tiny bones called auditory ossicles
oThree bones are located within each middle ear cavity, enclosed in the petrous part of the
temporal bone
oThey play a key role in hearing by conducting the vibrations produced by sound waves from the
tympanic membrane to the receptor complex of the internal ear
7.9 – FONTANELLES PERMIT CRANIAL GROWTH IN INFANTS AND SMALL CHILDREN
At birth, the cranial bones are connected by areas of flexible fibrous connective tissue that enable the
skull’s shape to change without damage to ease the infant’s passage through the birth canal
oThe largest fibrous areas between the cranial bones are known as fontanelles
The anterior fontanelle is often referred to as the “soft spot” on newborns and is often the only fontanelle
easily recognized by new parents
oGenerally persists until the child is nearly 2 years old
oThe largest fontanelle – it lies at the intersection of the frontal, sagittal, and coronal sutures in the
anterior portion of the skull
oBecause it is composed of fibrous connective tissue and covers a major blood vessel, the anterior
fontanelle pulses as the heart beats
Over time, the sutures gradually narrow and the fontanelles become smaller and smaller
The sphenoidal fontanelle on each side lies at the junction between the squamous suture and the
coronal surface
The mastoid fontanelle on each side lies at the junction between the squamous suture and the lambdoid
suture
The occipital fontanelle is at the junction between the lambdoid and sagittal sutures
The occipital, sphenoidal, and mastoid fontanelles disappear within a month or two after birth
7.10 – THE VERTEBRAL COLUMN HAS FOUR SPINAL CURVES, AND VERTEBRAE SHARE A BASIC
STRUCTURE THAT DIFFERS REGIONALLY
The adult vertebral column consists of 26 bones: 24 vertebrae, the sacrum, and the coccyx
The stacked vertebrae form a column of support that bears the weight of the head, neck, and trunk and
ultimately transfers the body’s weight to the appendicular skeleton of the lower limbs
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