Chapter 7 - The Skeleton Part I

Question 1

Fetal Skull

Answer 1

Bones are incomplete and are connected by fontanels
1. Fontanels – aka soft spot, the bone is un-ossified remnants of fibrous membrane. It allows the head to be compressed during birth and accommodate brain growth
a. Anterior fontanel
b. Posterior fontanel
c. Sphenoidal fontanel
d. Mastoid fontanel
B. Skull – 22 cranial and facial bones

Question 2

Skull

Answer 2

22 cranial and facial bones

1. Cranium – also divided into the vault and the base
   a. Functions – encloses and protects the brain and furnished attachment sites for head and neck muscles. Sutures are saw-toothed or serrated looking interlocking joints that are formed by bones of the adult bone
   b. Sutures
   c. Cranial vault – aka the calvaira; it forms the skull superior lateral and posterior aspects of the skull and forehead.
   d. Cranial base – aka the floor; it forms the skulls inferior aspect
   i. Fossa – internal divisions. First anterior carnial fossae, middle cranial fossae, and posterior cranial fossa

Question 3

Frontal Bone

Answer 3

One bone, shell shaped and it forms the anterior cranium
A. Coronal suture – where the parietal bones meet the frontal bone anteriorly
B. Frontal squama – the forehead, the vertical squamas part and it ends at the supraorbital margin
C. Supraorbital margin – thickened superioral margins of the orbits that lie under the eye brows
D. Supraorbital foramen – the opening above the orbit, it allows the supraorbital artery and nerve to pass to the forehead (hole in eyebrow)
E. Glabella – smooth portion of the frontal bone between the orbits (brow line)
F. Frontal sinus – lateral and internal to the glabella and it’s the rittled bone part
G. Zygomatic process – area near the zygomatic bone but on the frontal bone

Question 4

Parietal Bones

Answer 4

Two large curved rectangular bones that form the superior and lateral aspects of the skull (basically form the cranial vault).
A. Coronal suture – where the parietal bones meet the frontal bone anteriorly
B. Sagittal suture – parietal bones meet superiorly at the cranially midline
C. Lambdoid suture – where the parietal bones meet he occipital bone posteriorly
D. Squamous suture – where a parietal and temporal bone meet on the lateral aspect of the skull

Question 5

Occipital Bone

Answer 5

Forms most of the skulls posterior wall and base
A. Lambdoid suture – where the occipital bone meets the parietal bones
B. Occipitomastoid suture – temporal and occipital bones meet
C. Foramen magnum – large hole in the base of the occipital bone and this is where the inferior brain connects with the spinal column
D. Occipital condyle – rocker like, found on the inferior surface and they articulate with the first vertebra, which permits the ability to nod in a yes motion
E. Hypoglossal canal – hidden medially and superiorly to each condyle; it contains cranial nerve 12 the hypoglossal nerve
F. External occipital protuberance and crest – protrusion that are found just superior to the foramen magnum and this is the bulging parts of the skull, they serve as muscle attachment sites
G. Superior and inferior nuchal lines – inconspicuous ridges (connected to the external occipital protuberance and crest)

Question 6

Temporal Bones

Answer 6

Found inferior to the partial bone and they meet at the squamous suture

Question 7

Temporal Bones: Squamous Region

Answer 7

Area that’s adjacent to the squamous suture and it has a bar like process

1. Zygomatic process and arch – bar like process that meets with the zygomatic bone to form an arch
2. Mandibular fossa – small oval area found on the inferior surface of the zygomatic process, it receives the mandibula and forms what’s known as the moviable temporal-mandibular joint

Question 8

Temporal Bones: Tympanic Region

Answer 8

Area that surround the external acoustic meatus

1. External acoustic meatus – external ear canal through which sound enters
2. Styloid process – needle like and found below the external acoustic meatus and serves as an attachment point for: tongue and neck muscles and for a ligament that secures the hyoid bone of the neck to the skull

Question 9

Temporal Bones: Mastoid Region

Answer 9

Area which exhibits the mastoid process

1. Mastoid process – anchoring site for some neck muscles and is felt posterior to your ear

Question 10

Temporal Bones: Petrous Region

Answer 10

Miniature ridge found between the occipital bone (located posteriorly) and the sphenoid bone (located anteriorly)

1. Jugular foramen – found at the junction at the occipital bone and the petrous part of the temporal bone it allows for the passage for the internal jugular vein and cranial nerve 9, 10, 11
2. Carotid canal – anterior to the jugular foramen and transmits the internal collated artery
3. Foramen lacerum – opening between the petrous temporal bone and the sphenoid bone
4. Internal acoustic meatus – superior lateral to the jugular foramen allows for the cranial nerve 7 and 8 to pass

Question 11

Sphenoid Bone

Answer 11

Bat shaped and spans the width of the middle cranial fossa and articulates will all bones
A. Body – houses the sphenoid sinus
B. Sella turcica – saddle shaped propionate on the superior surface of the body
C. Hypophyseal fossa – the seat of the sella tursica and it forms an enclosure for the pituitary gland
D. Greater and lesser wings – help from anterior and posterior fossa; the greater wing will help form parts of the middle cranial fossa and the dorsal walls of the orbits and the external wall of the skull. The lesser wing form part of the floor of the anterior cranial fossa and part of the medial walls of the orbits
E. Pterygoid process – project inferiorly from the junction of the greater wing and body and anchors the pterygoid muscles
F. Optic canal – found anterior to the sella turcica and allows the optic nerve cranial nerve 2 to pass
G. Superior orbital fissure – long slit between the greater and lesser wing and allows for the passage of cranial nerve 3, 4, and 6. Inferior orbital fissure – make a number 7 with that and superior
H. Foramen rotundum and foramen ovale – carry branches of cranial nerve 5
I. Foramen spinosum – posterior lateral to the formaen ovale and it transmits the medial meningeal artery (SORO)
J. Sphenoid sinus - found within sphenoid body

Question 12

Ethmoid Bone

Answer 12

Found in between the sphenoid bone and nasal bones; it is the most deeply situated bone of the skull. It forms most of the nasal cavity and the orbit.
A. Cribriform plate – found on the superior surface of the ethmoid bone and forms the roof of the nasal cavity and the floor of the anterior cranial fossa
B. Olfactory foramen – tiny holes that allow filaments of the olfactory nerve to pass
C. Crista galli – triangular process which is found projecting superiorly, rooster’s comb
D. Perpendicular plate – projects inferiorly in the median plane and it forms the superior part of the nasal septum, which divides into right or left halves
E. Lateral mass and ethmoid sinus – flanking (sides) the perpendicular plate on each side and it’s riddled, with what’s known as ethmoid air cells
F. Superior and middle nasal conchae – extend medially from the lateral masses; they are delicately coiled and protrude into the nasal cavity

Question 13

Facial Bones

Answer 13

Made up 14 bones; mandible and vomer are unpaired
a. Functions – framework that contains special sense organs such as sight, taste and smell and provide opening for air and food passage. Also secure the teeth and anchor facial muscles

Question 14

Mandible

Answer 14

Lower jaw bone, largest and strongest bone of the face
A. Body – forms the chin and anchors the teeth
B. Ramus – two upright rami and they meet the body posteriorly
C. Mandibular angle – location where the body and the ramus meet
D. Coronoid process – incursion point for the temporalis muscles and this helps elevate the lower jaw
E. Mandibular condyle – articulates with the mandibular fosss of the tempular bone to form the tempular mandibular joint
F. Mandibular notch – separates the mandibular condyle and the coroniod process
G. Alveolar margin – superior boarder of the mandibular body and it carries the teeth
H. Mandibular symphysis – slight depression in the midline of the mandibular body (faceass)
I. Mandibular foramen – found in the medial surface of ramus and it permits the nerve of the lower jaw to pass
J. Mental foramen – openings in the lower mandible, nerves and blood vessels are going to pass through here to reach the skin of the chin and lower lip

Question 15

Maxillae

Answer 15

Fussed medially and forms the upper jaw and central portion of the facial skeleton
A. Alveolar margin – carries the teeth
B. Anterior nasal spine – junction where the maxillae meet medially
C. Palatine process – forms the anterior 2/3 of the hard palatine (roof of mouth)
D. Frontal process – forms the lateral aspects of the bridge of the nose
E. Zygomatic process – Zygomatic bone articulates with the maxillae bone
F. Inferior orbital fissure – deep within the orbit and junction of the maxillae and greater wing of the sphenoid bone
G. Infraorbital foramen – below the eye sockets and allows for the infraorbital artery and nerve to pass through
H. Maxillary sinus – flank the nasal cavity laterally

Question 16

Zygomatic Bones

Answer 16

Irregularly shaped cheekbone

Question 17

Nasal Bones

Answer 17

thin rectangular and fused medially forming the bridge of the nose

Question 18

Lacrimal Bones

Answer 18

Delicate finger nail shaped, and help form the medial wall of the orbit
A. Lacrimal fossa – deep grooves and they serve as the passage way for tears from the eyes to the nose

Question 19

Palatine Bone

Answer 19

L shaped, it has a perpendicular and horizontal palate. The horizontal palate complete the posterior portion of the hard plate. The perpendicular plates forms part of the posterolateral walls of the nasal cavity and a small part of the orbit

Question 20

Vomer

Answer 20

Slender it lays in the nasal cavity and it forms the bones in the nasal cavity

Question 21

Inferior Nasal Conchae

Answer 21

Thin curved bone, it is the largest of the 3 and it helps form the lateral walls of the nasal cavity

Question 22

Hyoid Bone

Answer 22

Not part of the skull, it’s found inferior to the mandible in the anterior neck

a. Body – moveable base, which is for the tongue and is the only bone in the body that doesn’t articulate with other bones
b. Greater and lesser horns

Question 23

Vertebral Column: Divisions

Answer 23

a. Cervical vertebrae – 7 vertebrae of the neck (Cervical vertebrae 1-7) (concave)
b. Thoracic vertebrae – 12 vertebrae – vertebrae of the thoracic cage (convex)
c. Lumbar vertebrae – 5 vertebrae – vertebra of the lower back (concave)
d. Sacrum – 5 fused vertebrae; bone inferior to the lumbar vertebrae (convex)
e. Coccyx – 4 fused vertebrae; terminus of vertebral column (concave)

Question 24

Abnormal Vertebral Column Curvatures

Answer 24

a. Scoliosis – abnormal lateral curve of the vertebral column
b. Kyphosis – hunchback
c. Lordosis – sway back; inward curvature

Question 25

Intervertebral Discs

Answer 25

Between vertebra, cushion like pads that are composed of 2 parts

a. Nucleus pulposus – inner gelatinous nucleus that gives the disc elasticity and compressibility
b. Anulus fibrosus – outer collar, which is composed of collagen and fibro cartledge

Question 26

General Structure of Vertebrae

Answer 26

a. Body
b. Vertebral arch
c. Vertebral foramen and vertebral canal
d. Pedicles
e. Laminae
f. Spinous process
g. Transverse processes
h. Superior and inferior articular processes
i. Facets
j. Intervertebral foramina

Question 27

C1 and C2

Answer 27

1. Atlas – C1
   A. Lateral masses – doesn’t have a body
   B. Facet for dens
2. Axis – C2
   A. Dens – cradled in the anterior arch of the atlas by the transverse ligaments, it acts as a pivot for the rotation of the atlas (no motion)

Question 28

Sacrum

Answer 28

Forms posterior wall of pelvis; articulates with L5 superiorly, and with auricular surfaces of the hip bones laterally

i. Superior articular processes
ii. Auricular surfaces
iii. Sacral promontory
iv. Transverse ridges – sites of fusion
v. Anterior and posterior sacral foramina
vi. Alae – winged part
vii. Median sacral crest – posterior aspect
viii. Lateral sacral crests
ix. Sacral canal – hole up at the top
x. Sacral hiatus – hole at the bottom

Question 29

Thoracic Cage

Answer 29

Sternum

a. Manubrium – first part of sternum
i. Clavicular notches – for the clavicle
ii. Jugular notch – for the jugular to insert
iii. Sternal angle – angle of Louis (part in between the junction between the manubrium and sternum body)
b. Body
i. Costal notches – for the ribs (on both sides of the body)
c. Xiphoid process
i. Xiphisternal joint – when it comes into contact with the sternum

Question 30

Ribs

Answer 30

Space in between ribs is called inter-costal spaces; costal cartilage (rib margin)

a. Classification of ribs – 12 pairs of ribs all attached posteriorly to the thoracic vertebra
i. Vertebrosternal ribs – 1-7 – true ribs; they attach directly to the stemumby costal cartilage
ii. Vertebrochondral ribs – 8-10 – false ribs not attached to sternum but indirectly attached
iii. Vertebral ribs – 11-12 (floating ribs) have no attachment to the sternum whatsoever
b. Structure of ribs
i. Shaft - length
ii. Head – where it goes into the vertebrae
iii. Neck – connected to the head
iv. Tubercle – attached to the neck
c. Intercostal spaces