Download The Skeletal System

SPPA 2050 Speech Anatomy and Physiology
The Skeletal System
For some, things do not get much drier than
skeletal anatomy. The main skeletal
components of the body are skull, mandible
and hyoid bone, the vertebral column, the
ribcage, the pelvic girdle, pectoral girdle,
upper limb and lower limb. You are to
learn about each of these by examining
relevant figures in Netter, remembering as
you go items from the following “laundry
lists.”
First, a few general terms that frequently
come up when discussing the skeletal
framework of the body.
Joint: an articulation of two or skeletal
structures
Suture: fibrous joint where opposed
surfaces are closely united. Key sutures for
the purposes of this course are the sagittal,
coronal, lamdoid and squamosal sutures.
Foramen/Meatus: opening or passage
Process/ Tubercle:
projection of bone
a prominence or
Fossa/facet: hollow or depressed area
Skull and mandible: A laundry list
The skull is a composite of a number of
bones. We divide the skull into the cranial
skeleton and the facial skeleton. The bones
of the cranial skeleton are all involved to
some degree in forming the cranial vault,
which protects the brain. The facial skeleton
is just that – a framework for the face and
mouth. In no particular order, the bones of
the cranial skeleton are as follows.
1. Frontal bone: This is an unpaired bone
that is located under the skin of the
forehead. The coronal suture attaches it to
parietal bones. Landmarks of note are the
glabella, a midsagittal prominence and the
supraorbital margin which bounds the
orbit superiorly.
2. Parietal bone: This is a paired bone that
forms the lateral surface of the skull. The
coronal suture attached the parietal bone to
the frontal bone and the sagittal suture
attached the two parietal bones in the
midline.
Finally the lambdoid suture
attached the parietal bones to the occipital
bones.
3. Occipital bone: The occipital bone is an
unpaired, bowl shaped bone that forms the
dorsal caudal wall of the cranium. The
lambdoid suture attaches it to the parietal
bones. It can be divided into squamous and
basiocciptal
portions.
Noteworthy
structures of the occipital bone include the
foramen magnum, through which the
brainstem/spinal cord projects, the occipital
condyles which articulate with the first
cervical
vertebra
(atlas),
and
the
hypoglossal canal, through which the
hypoglossal nerve passes.
4. Temporal bone: The temporal bone is a
paired bone that partly forms the lateral and
caudal wall of the cranium. It has a number
of structures that are relevant to our study of
speech anatomy including the external and
internal auditory meati, styloid process,
mastoid process, zygomatic process,
mandibular
fossa,
carotid
canal,
stylomastoid foramen, through which the
facial
nerve
passes,
and
the
temporomandibular joint. Finally the
temporal and occipital bones bound the
jugular foramen, through which the
glossopharyngeal, vagus and accessory
nerves pass.
5. Sphenoid bone: The sphenoid bone is an
unpaired bone that is not easily palpated. It
is an important bone since a number of
relevant muscles attach to it. It has a body,
and a pair of greater and lesser wings. On
the cranial surface in the midline is the sella
turcica (Turkish saddle), which houses the
SPPA 2050 Speech Anatomy and Physiology
pituitary gland). An important landmark on
the sphenoid bone is the pterygoid process,
from which projects a medial pterygoid
plate and hamulus and lateral pterygoid
plate.
The sphenoid bone contains a
number of openings. There is the superior
orbital fissure which allows communication
between the orbit and the cranium, the
foramen rotundum, which provides
passage for the maxillary portion of the
trigeminal nerve, the foramen ovale, which
provides passage for the mandibular branch
of the trigeminal nerve, and the foramen
spinosum.
6. Ethmoid bone: This is a relatively small,
unpaired bone located in the region of the
nasal cavity. Relevant landmarks are the
cribiform plate (cribiform=perforated), the
crista galli, a thick, triangular plate
projecting superiorly from the cribiform
plate, and the perpendicular plate
projecting below to form part of the nasal
septum.
In no particular, order, the bones of the
facial skeleton are as follows
1. Maxillary bone: This is a paired bone
that dominates the face below the eyes on
each side of the nose. It is the permanent
seat of the upper teeth and forms about ¾ of
the hard palate. The maxillary bone also
forms a good portion of the floor of the
nasal cavity and the roof of the oral cavity,
which are important boundaries of the vocal
tract. Notable landmarks are the alveolar
and palatine processes, the infraorbial
groove and the incisive fossa.
2. Zygomatic bone: This is a paired bone
that dominates the face lateral to the eyes.
The zygomatic bone articulates with the
maxilla and temporal bone (below) and is an
important site of attachment for many lip
and jaw muscles. Noteworthy landmarks
are the frontal, maxillary and temporal
processes.
3. Palatine bone: This is a relatively small,
paired bone that articulates with the
maxilla. It makes up the dorsal (posterior)
¼ of the hard palate and lateral walls of
nasal cavity. The palatine bone is “L”
shaped looking ventrally or dorsally.
4. Inferior nasal concha: This paired bone
projects medially from the palatine and
maxillary bones.
5. Vomer bone: This unpaired bone forms
a portion of the nasal septum, which
separates the nasal cavity into dextral and
sinistral chambers.
6. Nasal bone: This paired bone forms part
of the bony skeleton of the nose medial to
the orbits (eye sockets).
7. Lacrimal bone: This small, paired bone
helps for the medial wall of the orbit.
Mandible: The mandible is an unpaired
bone that forms the bony skeleton of the
lower jaw. It is the permanent site of the
lower teeth and articulates with the temporal
bone (temporomandibular joint). Relevant
landmarks include the neck and head of the
condylar process, alveolar process, mental
protuberance, mental foramen,
mandibular foramen, coronoid process,
ramus, angle and body.
Hyoid Bone: The hyoid bone is a small,
horseshoe-shaped bone that is located in the
neck and is associated with the larynx. It
will be discussed in Chapter V.
Spinal Column: A laundry list
1. There are five types of vertebrae –
cervical, thoracic, lumbar, sacral, and
coccygeal, and there are 7, 12, 5, 5 (but
fused), and (usually) 4 (also sometimes
fused) of each type. All vertebrae are
“named” in the same way that spinal nerves
are named, by a capital letter indicating
“family” or region (e.g., C, T, etc.), and an
Arabic numeral indicating rostral-to-caudal
position (where 1 is always most rostral
relative to other vertebrae in the same
family).
2. Two cervical vertebrae, C1 and C2, have
special names: atlas and axis, respectively.
3. The thoracic vertebrae provide a dorsal
suspensory framework for the ribs. Cervical,
SPPA 2050 Speech Anatomy and Physiology
thoracic, and lumbar vertebrae provide
attachment sites for muscles that may play a
role in respiratory movement. The sacral
vertebrae “cement” the two halves of the
pelvic girdle together, in the midline, and
thus, contribute to the foundation of the
respiratory system. The coccygeal vertebrae
-- our vestigial tails -- may well be useless.
We could probably lose them, like tadpoles
lose their tails, and no one would be any
worse off.
4. Many vertebrae have many features in
common, including: a vertebral foramen,
spinous and transverse processes, a
corpus or body, the pedicle, superior and
inferior articular processes and facets and
the costal facets. Some vertebrae have
special features, including: the dorsal
tubercle of C1; the dens of C2; the
transverse
foraminae
of
C1-C7;
progressively larger bodies as we move
caudally in the column, from cervical to
lumbar; sacral crests on the dorsal surface of
sacral vertebrae, instead of spinous
processes; no vertebral foramen for the any
of the coccygeal vertebrae.
Rib Cage: A laundry list
1. There are twelve pairs of ribs in all –
generally true for males and females, no
matter what you might have heard to the
contrary. The rostral-most seven pairs (R1R7) are usually called true ribs. Each of
these connects “directly” to the sternum, on
the ventral side of the body, by virtue of its
own cartilage that spans the space between
the end of the bony (osseous) part of the rib,
and the lateral margin of the sternum. The
cartilaginous extension from any rib that has
one is sometimes referred to as the chondral
portion of the rib. The remaining five rib
pairs (R8-R12) are usually called false ribs.
(Tell your eighth rib that, when you break
it.) The caudal-most rib pairs (R11 and R12)
float (i.e., do not attach to the sternum by
cartilage, even indirectly). The three nonfloating false rib pairs (R8-R10) connect to
the sternum “indirectly” by virtue of
ascending cartilaginous extensions that join
the cartilage belonging to R7.
2. The term costal is often used in place of
the term rib. Thus, the juncture between the
osseous and cartilaginous portion of each of
the true ribs is sometimes called the
costochondral juncture.
3. Roughly speaking, each rib articulates
with a thoracic vertebra of the same number
(e.g., R1 with T1, R2 with T2), on the dorsal
side of the body. The head and neck of each
rib “fits” along the ventral surface of the
transverse process of the corresponding rib.
Key landmarks are the tubercle, angle,
head, neck, shaft and costal groove. These
landmarks can be understood well enough
by examining the figures and anatomical
specimens.
4. The sternum is usually said to have three
parts: manubrium, body (or corpus), and
xiphoid process. R1 joins the sternum (by
virtue of its cartilage) at the manubrium; R2
joins the sternum at the immobile joint
between the manubrium and corpus; R3-R7
join the corpus at progressively lower levels,
but above the xiphoid process. Additional
landmarks include the suprasternal or
jugular notch, the clavicular notches, the
sternal angle, the costal notches, and the
manubriosternal and xiphisternal joints.
5. The ribs and sternum provide an
important part of the walls of the thorax.
The ribs also provide many attachment sites
for muscles we use to vary thoracic volume.
Finally; we can say that the ribs provide
considerable protection for crucial organs
(the heart and lungs).
Pelvic Girdle: A laundry list
1. There are three bony components to each
(dextral or sinistral) half of the pelvic girdle:
the ilium, ischium, and pubis. The two
halves of the pelvic girdle are “bridged”
dorsally, across the midline, by the fused
sacral vertebrae. Perhaps you have heard of
SPPA 2050 Speech Anatomy and Physiology
the sacroiliac joint. On the ventral side, the
halves are bridged by a cartilaginous “disk”
joining the pubic bones. This juncture is
usually referred to as the pubic symphysis.
2. Prominent landmarks associated with the
pelvic girdle include: the iliac crest; the
acetabulum; and the stout inguinal
ligament, which spans the space between
the anterior superior iliac spine, and the
pubic tubercle.
3. The pelvis provides a hard floor for the
trunk, and ultimately, for the respiratory
system. In a way, the pelvis keeps the
visceral contents of your abdomen from
falling on the floor, forcing them instead
against the diaphragm, when you “squeeze
your middle” to expire (actively).
4. As always, with any skeletal components
that concern us, the bones of the pelvis
provide attachment sites for certain muscles
implicated in respiration.
Pectoral Girdle: A laundry list
1. There are two bony components of the
pectoral girdle: the clavicle and scapula
(probably known to you in your former life
as the collarbone and shoulder blade). The
S-shaped clavicle, on the ventral side of the
body, articulates medially with the
manubrium of the sternum at the
sternoclavicular joint.
The clavicle
articulates laterally with the scapula at a
distinctive landmark (on the scapula) known
as the acromion. Therefore, we can divide
the clavicle into a sternal end, a shaft and
an acromial end. The triangularly shaped,
plate-like scapula, on the dorsal side of the
body, articulates only with the clavicle and
no other bone.
2. Distinctive landmarks associated with the
scapula include its spine, the acromion, the
coracoid process, and the glenoid cavity
(sometimes also referred to as a facet or
fossa).
3. The bones of the pectoral girdle provide
attachment sites for several muscles that
many have speculated may contribute in
some (usually indirect) way to inspiration
and/or
expiration
(e.g.,
the
sternocleidomastoid; rhomboid, serratus
anterior, pectoralis major and minor, and the
like).
Note: The bones of the upper and lower limb
are not covered in the laboratory component
of the course. However, you should be able
to generally identify these structures for
lecture.
Upper Limb: A laundry list
1.
2.
3.
4.
5.
6.
humerus (arm)
radius (forearm)
ulna (forearm)
carpal bones (wrist)
metacarpal bones (hand)
phalanges (fingers)
Lower Limb: A laundry list
1.
2.
3.
4.
5.
6.
femur (thigh)
tibia (leg)
fibula (leg)
tarsal bones (ankle)
metatarsal bones (foot)
phalanges (toes)