L5: Axial Pt. 1 Flashcards
contribute to homeostasis by protecting many of the body’s organs such as the brain, spinal cord, heart, and lungs. They are also important in support and calcium storage and release.
bones of the axial skeleton
What would happen without bones?
You could not survive.
What movements would you be unable to perform without bones?
Walking or grasping.
What could happen if you received the slightest blow to your head or chest without bones?
It could damage your brain or heart.
What does the skeletal system form?
The framework of the body.
Why is it important to be familiar with the names, shapes, and positions of individual bones?
It will help you locate and name many other anatomical features.
What is the radial artery named for?
Its closeness to the radius, the lateral bone of the forearm.
What is the ulnar nerve named for?
Its proximity to the ulna, the medial bone of the forearm.
Where does the frontal lobe of the brain lie?
Deep to the frontal (forehead) bone.
Where does the tibialis anterior muscle lie?
Along the anterior surface of the tibia (shin bone).
What do parts of certain bones help to locate and outline?
Structures within the skull and the lungs, heart, and abdominal and pelvic organs.
What do movements such as throwing a ball, biking, and walking require?
Interactions between bones and muscles.
What do you need to learn to understand how muscles produce different movements?
Where the muscles attach on individual bones and what types of joints are involved.
What do the bones, muscles, and joints together form?
The musculoskeletal system.
What is the branch of medical science concerned with the prevention or correction of disorders of the musculoskeletal system called?
Orthopedics.
How many named bones does the adult human skeleton consist of?
206 named bones.
Why do the skeletons of infants and children have more than 206 bones?
Because some of their bones fuse later in life.
What are examples of bones that fuse later in life?
The hip bones and some bones (sacrum and coccyx) of the vertebral column (backbone).
What are the two principal divisions of the adult skeleton?
The axial skeleton and the appendicular skeleton.
How many bones are in the axial skeleton?
80 bones.
How many bones are in the appendicular skeleton?
126 bones.
How can you remember the names of the divisions of the skeleton?
By thinking of the axial skeleton as consisting of the bones that lie around the axis of the human body.
What are the bones of the axial skeleton?
Skull bones, auditory ossicles (ear bones), hyoid bone, ribs, sternum (breastbone), and bones of the vertebral column.
What does the appendicular skeleton consist of?
The bones of the upper and lower limbs (extremities or appendages), plus the bones forming the girdles that connect the limbs to the axial skeleton.
What is the functional role of the auditory ossicles in the middle ear?
They vibrate in response to sound waves that strike the eardrum.
Why are the auditory ossicles grouped with the axial skeleton?
For convenience.
How is the study of the skeletal system organized?
Around the two divisions of the skeleton, with emphasis on how the many bones of the body are interrelated.
The adult human skeleton consists of 206 bones grouped into two divisions:
axial skeleton and the appendicular skeleton.
The ___ of bones largely determine their functions.
shapes
Into how many main types can almost all bones of the body be classified based on shape?
Five main types.
What are the five main types of bones based on shape?
Long, short, flat, irregular, and sesamoid.
What do long bones have greater than width?
Length.
What do long bones consist of?
A diaphysis (body) and a variable number of extremities or epiphyses (ends).
Why are long bones slightly curved?
For strength.
What does a curved bone do to the strain of the body’s weight?
Absorbs it at several different points, so that it is evenly distributed.
What would happen if bones were straight?
The weight of the body would be unevenly distributed, and the bone would fracture more easily.
What do long bones mostly consist of in their diaphyses?
Compact bone tissue.
What do long bones have considerable amounts of in their epiphyses?
Spongy bone tissue.
What are examples of long bones?
Femur (thigh bone), tibia and fibula (leg bones), humerus (arm bone), ulna and radius (forearm bones), and phalanges (finger and toe bones).
What shape are short bones?
Somewhat cube-shaped.
How do the length and width of short bones compare?
They are nearly equal in length and width.
What do short bones mostly consist of?
Spongy bone tissue, except at the surface, which has a thin layer of compact bone tissue.
What are examples of short bones?
Most carpal (wrist) bones and most tarsal (ankle) bones.
How are flat bones generally shaped?
Thin.
What are flat bones composed of?
Two nearly parallel plates of compact bone tissue enclosing a layer of spongy bone tissue.
What do flat bones provide?
Considerable protection and extensive areas for muscle attachment.
What are examples of flat bones?
Cranial cavity bones (which protect the brain), sternum, and ribs (which protect organs in the thorax).
What kind of shapes do irregular bones have?
Complex shapes.
Why can irregular bones not be grouped into other categories?
Because of their complex shapes.
What do irregular bones vary in?
The amount of spongy and compact bone present.
What are examples of irregular bones?
Vertebrae (backbones), hip bones, certain facial bones, and the calcaneus (heel bone).
What are sesamoid bones shaped like?
A sesame seed.
Where do sesamoid bones develop?
In certain tendons where there is considerable friction, tension, and physical strain, such as the palms and soles.
Do sesamoid bones vary in number from person to person?
Yes.
Are sesamoid bones always completely ossified?
No.
How large are sesamoid bones typically?
Only a few millimeters in diameter.
What are the notable exceptions among sesamoid bones?
The two patellae (kneecaps).
Where are the patellae located?
In the quadriceps femoris tendon.
Are patellae normally present in everyone?
Yes.
What is the function of sesamoid bones?
To protect tendons from excessive wear and tear and often change the direction of pull of a tendon, improving mechanical advantage at a joint.
What additional type of bone is classified by location rather than shape?
Sutural bones.
Where are sutural bones located?
In sutures (joints) between certain cranial cavity bones.
Does the number of sutural bones vary from person to person?
Yes.
What do bones have?
Characteristic surface markings.
What are characteristic surface markings?
Structural features adapted for specific functions.
Are most surface markings present at birth?
No.
When do most surface markings develop?
In response to certain forces and are most prominent in the adult skeleton.
What happens in response to tension on a bone surface from tendons, ligaments, aponeuroses, and fasciae?
New bone is deposited, resulting in raised or roughened areas.
What happens in response to compression on a bone surface?
A depression results.
How many major types of surface markings are there?
Two.
What are the two major types of surface markings?
Depressions and openings, and processes.
What is the function of depressions and openings?
They allow the passage of soft tissues (such as blood vessels, nerves, ligaments, and tendons) or form joints.
What are processes?
Projections or outgrowths that either help form joints or serve as attachment points for connective tissue (such as ligaments and tendons).
Sites allowing the passage of soft tissue (nerves, blood vessels, ligaments, tendons) or formation of joints
depressions and openings
projections or outgrowths on bone that form joints or attachment points for connective tissue, such as ligaments and tendons
processes
processes that form joints
condyle, facet, and head
processes that form attachment points for connective tissue
crest, epicondyle, line, spinous process, trochanter, tubercle, and tuberosity
Narrow slit between adjacent parts of bones through which blood vessels or nerves pass.
Fissure
Example of fissure
Superior orbital fissure of sphenoid bone
Opening through which blood vessels, nerves, or ligaments pass.
Foramen
Example of Foramen
Optic canal of sphenoid bone
Shallow depression.
Fossa
Example of Fossa
Coronoid fossa of humerus
Furrow along bone surface that accommodates blood vessel, nerve, or tendon.
Sulcus
Example of Sulcus
Intertubercular sulcus of humerus
Tubelike opening.
Meatus
Example of Meatus
External acoustic meatus of temporal bone
Large, round protuberance with a smooth articular surface at end of bone.
Condyle
Example of Condyle
Lateral condyle of femur
Smooth, flat, slightly concave or convex articular surface.
Facet
Example of Facet
Superior articular facet of vertebra
Usually rounded articular projection supported on neck (constricted portion) of bone.
Head
Example of Head
Head of femur
Prominent ridge or elongated projection.
Crest
Example of crest
Iliac crest of hip bone
Typically roughened projection above condyle
Epicondyle
Example of epicondyle
Medial epicondyle of femur
Long, narrow ridge or border (less prominent than crest).
Line
Example of line
Linea aspera of femur
Sharp, slender projection.
Spinous process
Example of spinous process
Spinous process of vertebra
Very large projection.
Trochanter
Example of trochanter
Greater trochanter of femur
Variably-sized rounded projection.
Tubercle
Example of tubercle
Greater tubercle of humerus
Variably-sized projection that has a rough, bumpy surface.
Tuberosity
Example of tuberosity
Ischial tuberosity of hip bone
What is the skull?
The bony framework of the head.
How many bones does the skull contain (excluding the middle ear bones)?
22 bones.
Where does the skull rest?
On the superior end of the vertebral column (backbone).
How are the bones of the skull grouped?
Into two parts: cranial cavity bones and facial bones.
What do cranial cavity bones form?
The cranial cavity.
What is the floor of the cranial cavity called?
The cranial base.
How many bones form the cranial cavity?
8 bones.
What are the 8 bones that form the cranial cavity?
Frontal bone, two parietal bones, two temporal bones, occipital bone, sphenoid bone, and ethmoid bone.
What do facial bones form?
The anterior part of the skull.
What structures do facial bones surround?
The mouth (upper and lower jaw), nose, nasal cavity, and most of the orbits (eye sockets).
How many facial bones are there?
14 facial bones.
What are the 14 facial bones?
Two nasal bones, two maxillae, two zygomatic bones, mandible, two lacrimal bones, two palatine bones, two inferior nasal concha bones, and vomer.
Besides the large cranial cavity, what other cavities does the skull contain?
The nasal cavity and orbits (eye sockets).
What are paranasal sinuses?
Cavities in certain skull bones that are lined with mucous membranes and open into the nasal cavity.
Where are the small middle-ear cavities located?
In the temporal bones.
What structures do the small middle-ear cavities house?
The structures involved in hearing and equilibrium (balance).
Other than the auditory ossicles, which is the only movable bone of the skull?
The mandible.
What are sutures?
Joints that attach most of the skull bones together.
Where are sutures especially noticeable?
On the outer surface of the skull.
What are foramina?
Rounded passageways in the skull through which blood vessels and nerves pass.
What are fissures?
Slitlike openings in the skull through which blood vessels and nerves pass.
Besides protecting the brain, what else do the cranial cavity bones do?
They stabilize the positions of the brain, blood vessels, lymphatic vessels, and nerves through the attachment of their inner surfaces to meninges (membranes).
What do the outer surfaces of cranial cavity bones provide?
Large areas of attachment for muscles that move various parts of the head.
What else do the bones of the skull provide attachment for?
Some muscles that produce facial expressions.
What do facial bones form?
The framework of the face.
What do facial bones provide support for?
The entrances to the digestive and respiratory systems.
What do the cranial cavity and facial bones protect and support?
The delicate special sense organs for vision, taste, smell, hearing, and equilibrium.
What does the frontal bone form?
The forehead (the anterior part of the skull), the roofs of the orbits (eye sockets), and most of the anterior part of the cranial base.
What unites the left and right sides of the frontal bone soon after birth?
The metopic suture.
When does the metopic suture usually disappear?
Between the ages of six and eight.
What is the frontal squama?
A scalelike plate of bone that forms the forehead of the skull.
Where does the frontal squama gradually slope from?
The coronal suture, on the top of the skull.
What happens to the frontal squama as it moves inferiorly?
It angles abruptly and becomes almost vertical above the orbits.
What does the frontal bone thicken to form at the superior border of the orbits?
The supraorbital margin.
What does the frontal bone extend posteriorly to form from the supraorbital margin?
The roof of the orbit, which is part of the cranial base.
What is the supraorbital foramen?
A hole within the supraorbital margin, slightly medial to its midpoint.
What is the incomplete form of the supraorbital foramen called?
The supraorbital notch.
What lies deep to the frontal squama?
The frontal sinuses.
What are sinuses, or more technically, paranasal sinuses?
Mucous membrane–lined cavities within certain skull bones.
What is a black eye?
A bruising around the eye, commonly due to an injury to the face rather than an eye injury.
What happens in response to trauma in a black eye?
Blood and other fluids accumulate in the space around the eye, causing the swelling and dark discoloration.
What is one cause of a black eye?
A blow to the sharp ridge just superior to the supraorbital margin that fractures the frontal bone, resulting in bleeding.
What is another cause of a black eye?
A blow to the nose.
What surgical procedures can result in black eyes?
Face lift, eyelid surgery, jaw surgery, or nasal surgery.
What do the two parietal bones form?
The greater portion of the sides and roof of the cranial cavity.
What do the internal surfaces of the parietal bones contain?
Many protrusions and depressions that accommodate the blood vessels supplying the dura mater.
What is the dura mater?
The superficial connective tissue (meninx) covering of the brain.
consists of cranial cavity bones and facial bones
Skull
is formed by the zygomatic process of the temporal bone and the temporal process of the zygomatic bone.
zygomatic arch
The cranial cavity bones are the
frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones
The facial bones are the
nasal bones, maxillae, zygomatic bones, lacrimal bones, palatine bones, inferior nasal concha bones, mandible, and vomer.
What do the paired temporal bones form?
The inferior lateral aspects of the cranial cavity and part of the cranial base.
What is the temporal squama?
The thin, flat part of the temporal bone that forms the anterior and superior part of the temple.
What does the zygomatic process articulate with?
The temporal process of the zygomatic (cheek) bone.
What forms the zygomatic arch?
The zygomatic process of the temporal bone and the temporal process of the zygomatic bone.
What is the mandibular fossa?
A socket located on the inferior posterior surface of the zygomatic process of each temporal bone.
What is located anterior to the mandibular fossa?
The articular tubercle.
What do the mandibular fossa and articular tubercle articulate with?
The mandible (lower jawbone) to form the temporomandibular joint (TMJ).
Where is the mastoid portion of the temporal bone located?
Posterior and inferior to the external acoustic meatus (ear canal).
What does the external acoustic meatus do?
Directs sound waves into the ear.
What are mastoid air cells?
Tiny air-filled compartments within the mastoid portion that communicate with the middle ear.
What can happen if a middle ear infection spreads into the mastoid air cells?
It can cause a painful inflammation called mastoiditis.
What is the mastoid process?
A rounded projection of the mastoid portion of the temporal bone posterior and inferior to the external acoustic meatus.
What is the mastoid process a point of attachment for?
Several neck muscles.
What is the internal acoustic meatus?
The opening through which the facial (VII) nerve and vestibulocochlear (VIII) nerve pass.
What is the styloid process?
A projection that extends inferiorly from the inferior surface of the temporal bone.
What does the styloid process serve as?
A point of attachment for muscles and ligaments of the tongue and neck.
Where is the stylomastoid foramen located?
Between the styloid process and the mastoid process.
What passes through the stylomastoid foramen?
The facial (VII) nerve and stylomastoid blood vessels.
Where is the petrous portion of the temporal bone located?
At the base of the skull between the sphenoid and occipital bones.
What does the petrous portion house?
The internal ear and middle ear, structures involved in hearing and equilibrium (balance).
What passes through the carotid canal?
The carotid artery.
Where is the jugular foramen located?
Posterior to the carotid canal and anterior to the occipital bone.
What passes through the jugular foramen?
The jugular vein and three cranial nerves
forms most of the posterior and inferior portions of the cranial cavity.
occipital bone
What does the occipital bone form?
The posterior part of the cranial cavity and most of the cranial base.
Where is the foramen magnum located?
In the inferior part of the occipital bone.
What passes through the foramen magnum?
The medulla oblongata, vertebral and spinal arteries, and the accessory (XI) nerve.
What are the occipital condyles?
Oval processes with convex surfaces on either side of the foramen magnum.
What do the occipital condyles articulate with?
Depressions on the first cervical vertebra (atlas) to form the atlanto-occipital joint.
What movement does the atlanto-occipital joint allow?
Nodding the head “yes.”
Where is the hypoglossal canal located?
Superior to each occipital condyle on the inferior surface of the skull.
What is the external occipital protuberance?
The most prominent midline projection on the posterior surface of the occipital bone just above the foramen magnum.
Where can you feel the external occipital protuberance?
As a bump on the back of your head, just above your neck.
What is the ligamentum nuchae?
A large fibrous, elastic ligament that extends from the external occipital protuberance to the seventh cervical vertebra.
What is the function of the ligamentum nuchae?
To help support the head.
What extends laterally from the external occipital protuberance?
Two curved ridges called the superior nuchal lines.
What is located below the superior nuchal lines?
Two inferior nuchal lines.
What is the function of the superior and inferior nuchal lines?
They serve as areas of muscle attachment.
articulate with the first cervical vertebra to form the atlanto-occipital joint.
occipital condyles of the occipital bone
is called the keystone of the cranial base because it articulates with all other cranial base bones, holding them together.
sphenoid bone
What is the sphenoid bone also called?
Keystone of the cranial base
Why is the sphenoid bone called the keystone of the cranial base?
Because it articulates with all the other cranial cavity bones of the cranial base, holding them together.
With which bones does the sphenoid bone join anteriorly?
Frontal and ethmoid bones
With which bones does the sphenoid bone join laterally?
Temporal bones
With which bone does the sphenoid bone join posteriorly?
Occipital bone
Where does the sphenoid bone lie in relation to the nasal cavity?
Posterior and slightly superior
What parts of the orbit does the sphenoid bone form?
Part of the floor, side walls, and rear wall
What shape does the sphenoid bone resemble?
A butterfly with outstretched wings
What is the hollowed cubelike medial portion of the sphenoid bone called?
Body of the sphenoid
Between which bones is the body of the sphenoid located?
Ethmoid and occipital bones
What is the space inside the body of the sphenoid called?
Sphenoidal sinus
Where does the sphenoidal sinus drain into?
Nasal cavity
What is the sella turcica?
A bony saddle-shaped structure on the superior surface of the body of the sphenoid
What is the anterior part of the sella turcica called?
Tuberculum sellae
What is the seat of the saddle in the sella turcica?
Hypophyseal fossa
What does the hypophyseal fossa contain?
Pituitary gland
What is the posterior part of the sella turcica called?
Dorsum sellae
What projects laterally from the body of the sphenoid?
Greater wings
What do the greater wings form?
Anterolateral cranial base, part of the lateral wall of the cranial cavity, and orbit just anterior to the temporal bone
Where can the greater wings be viewed?
Externally
What forms a ridge of bone anterior and superior to the greater wings?
Lesser wings
What do the lesser wings form?
Part of the cranial base and the posterior part of the orbit of the eye
What is located between the body and lesser wing, just anterior to the sella turcica?
Optic canal (foramen)
What passes through the optic canal?
Optic (II) nerve and ophthalmic blood vessels
What is the triangular slit lateral to the body between the greater and lesser wings?
Superior orbital fissure
What passes through the superior orbital fissure?
Blood vessels and cranial nerves
What projects inferiorly from the points where the body and greater wings of the sphenoid unite?
Pterygoid processes
What do the pterygoid processes form?
Lateral posterior region of the nasal cavity
What attaches to the pterygoid processes?
Some muscles that move the mandible
What is located at the base of the lateral pterygoid process in the greater wing?
Foramen ovale
What does the foramen lacerum transmit?
A branch of the ascending pharyngeal artery
What bones bound the foramen lacerum anteriorly?
Sphenoid bone
What bones bound the foramen lacerum medially?
Sphenoid and occipital bones
What foramen is located at the junction of the anterior and medial parts of the sphenoid bone?
Foramen rotundum
What passes through the foramen rotundum?
Maxillary division of the trigeminal (V) nerve
forms part of the anterior portion of the cranial base, the medial wall of the orbits, the superior portions of the nasal septum, and most of the side walls of the nasal cavity.
ethmoid bone
What is the ethmoid bone?
A delicate bone located in the anterior part of the cranial base medial to the orbits and is spongelike in appearance
Where is the ethmoid bone located?
In the anterior part of the cranial base medial to the orbits
What is the appearance of the ethmoid bone?
Spongelike
What bones are anterior and posterior to the ethmoid bone?
Anterior to the sphenoid and posterior to the nasal bones
What does the ethmoid bone form?
Part of the anterior portion of the cranial base, the medial wall of the orbits, the superior portion of the nasal septum, and most of the superior sidewalls of the nasal cavity
What is the major superior supporting structure of the nasal cavity?
Ethmoid bone
What does the ethmoid bone form in the nasal cavity?
An extensive surface area
Into what portions is the ethmoid bone divided?
A horizontal portion (cribriform plate), a median perpendicular plate, and two lateral portions (ethmoidal labyrinths)
What is the cribriform plate?
A horizontal portion of the ethmoid bone that forms part of the cranial base
What does the cribriform plate form?
The roof of the nasal cavity
What does the cribriform plate contain?
Cribriform foramina
What passes through the cribriform foramina?
Olfactory (I) nerves
What is the triangular process projecting superiorly from the cribriform plate?
Crista galli
What is the function of the crista galli?
It serves as a point of attachment for the falx cerebri
What is the falx cerebri?
The membrane that separates the two cerebral hemispheres of the brain
What does the median perpendicular plate form?
The superior portion of the nasal septum
What are the ethmoidal labyrinths?
Two lateral masses on either side of the perpendicular plate
What do the ethmoidal labyrinths compose?
Most of the wall between the nasal cavity and orbits
What do the ethmoidal labyrinths contain?
3–18 air sinus spaces called ethmoidal cells
What are the lateral surfaces of the ethmoidal labyrinths called?
Orbital plates
What do the orbital plates help form?
The medial walls of the orbits
What are the two thin, scroll-shaped projections lateral to the nasal septum called?
Superior nasal concha and middle nasal concha
What is the plural form of concha?
Nasal conchae
What is the third pair of conchae that are separate bones called?
Inferior nasal conchae
What do the conchae increase in the nasal cavity?
The vascular and mucous membrane surface area
What is the function of the conchae?
To warm and moisten (humidify) inhaled air before it passes into the lungs
What does the swirling effect of the conchae do?
Traps many inhaled particles in the mucus that lines the nasal cavity
What is the function of the conchae in relation to inhaled air?
They help cleanse inhaled air before it passes into the respiratory passageways
Where are the superior nasal conchae located?
Near the cribriform foramina of the cribriform plate
Where do the sensory receptors for olfaction terminate?
In the mucous membrane of the superior nasal conchae
What is the function of the superior nasal conchae in relation to smell?
They increase the surface area for the sense of smell
When does the shape of the face change dramatically?
During the first two years after birth
What expands during the first two years after birth?
The brain and skull bones
What forms and erupts during the first two years after birth?
The first set of teeth
What increases in size during the first two years after birth?
The paranasal sinuses
When does the growth of the face cease?
At about 16 years of age
How many facial bones are there?
14
What are the 14 facial bones?
Two nasal bones, two maxillae (or maxillas), two zygomatic bones, the mandible, two lacrimal bones, two palatine bones, two inferior nasal concha bones, and the vomer
What shape are the paired nasal bones?
Small, flattened, rectangular-shaped
What do the paired nasal bones form?
The bridge of the nose
What do the small nasal bones protect?
The upper entry to the nasal cavity
What do the paired nasal bones provide attachment for?
A couple of thin muscles of facial expression
What bones form the resting place for the bridge of glasses?
Nasal bones
What does the major structural portion of the nose consist of?
Cartilage
What are the paired lacrimal bones?
Thin and roughly resemble a fingernail in size and shape
What are the smallest facial bones?
Lacrimal bones
Where are the lacrimal bones located?
Posterior and lateral to the nasal bones
What part of the orbit do the lacrimal bones form?
Part of the medial wall of each orbit
What does each lacrimal bone contain?
A lacrimal fossa
What is the lacrimal fossa?
A vertical tunnel formed with the maxilla
What does the lacrimal fossa house?
The lacrimal sac
What is the function of the lacrimal sac?
To gather tears and pass them into the nasal cavity
What do the two L-shaped palatine bones form?
The posterior portion of the hard palate, part of the floor and posterolateral wall of the nasal cavity, and a small portion of the floors of the orbits
What forms the posterior portion of the hard palate?
The horizontal plates of the palatine bones
What are the two inferior nasal concha bones also called?
Turbinates
Where are the inferior nasal concha bones located?
Inferior to the middle nasal conchae of the ethmoid bone
Are the inferior nasal concha bones part of the ethmoid bone?
No, they are separate bones
What do the scroll-like inferior nasal concha bones form?
A part of the inferior lateral wall of the nasal cavity
Where do the inferior nasal concha bones project?
Into the nasal cavity
What do all three pairs of nasal conchae increase?
The surface area of the nasal cavity
What do all three pairs of nasal conchae help do?
Swirl and filter air before it passes into the lungs
Which nasal conchae are covered by the olfactory epithelium and involved in the sense of smell?
Superior nasal conchae of the ethmoid bone
When do the palatine processes of the maxillary bones usually unite during embryonic development?
During weeks 10 to 12
What can result from the failure of the palatine processes of the maxillary bones to unite?
One type of cleft palate
What may also involve incomplete fusion of the horizontal plates of the palatine bones?
Cleft palate
What is another form of this condition that involves a split in the upper lip?
Cleft lip
What conditions often occur together?
Cleft lip and cleft palate
What may be affected depending on the extent and position of the cleft?
Speech and swallowing
What do children with cleft palate tend to have?
Many ear infections
What can frequent ear infections in children with cleft palate lead to?
Hearing loss
When do facial and oral surgeons recommend closure of cleft lip?
During the first few weeks following birth
How are the surgical results for cleft lip repair?
Excellent
When is the repair of cleft palate typically completed?
Between 12 and 18 months of age
Why is cleft palate ideally repaired before the child begins to talk?
Because the palate is important for pronouncing consonants
What therapy may be required after cleft palate repair?
Speech therapy
What therapy may be needed to align the teeth?
Orthodontic therapy
What has recent research strongly suggested decreases the incidence of cleft palate and cleft lip?
Supplementation with folic acid
What is folic acid?
One of the B vitamins
Is the mechanism behind folic acid’s effect on cleft palate and cleft lip understood?
No, it is not yet understood
What is the vomer?
A roughly triangular bone
What does the vomer form?
The inferior part of the nasal septum
With what does the vomer articulate superiorly?
The perpendicular plate of the ethmoid bone and sphenoid bone
With what does the vomer articulate inferiorly?
Both the maxillae and palatine bones along the midline
What do the paired maxillae unite to form?
The upper jawbone
With which facial bone do the maxillae not articulate?
The mandible (lower jawbone)
What parts of the skull do the maxillae form?
Part of the floors of the orbits, part of the lateral walls and floor of the nasal cavity, and most of the hard palate
What is the hard palate?
The bony roof of the mouth
What forms the hard palate?
The palatine processes of the maxillae and horizontal plates of the palatine bones
What does the hard palate separate?
The nasal cavity from the oral cavity
What does each maxilla contain?
A large maxillary sinus
Where does the maxillary sinus empty?
Into the nasal cavity
What is the alveolar process of the maxilla?
A ridgelike arch that contains the dental alveoli (sockets) for the maxillary (upper) teeth
What is the palatine process of the maxilla?
A horizontal projection of the maxilla that forms the anterior three-quarters of the hard palate
When is the union and fusion of the maxillary bones normally completed?
Before birth
What condition results if the maxillary bones fail to fuse?
Cleft palate
What is the infraorbital foramen?
An opening in the maxilla inferior to the orbit
What passes through the infraorbital foramen?
The infraorbital blood vessels and nerve, a branch of the maxillary division of the trigeminal (V) nerve
What is the incisive foramen?
A foramen in the maxilla just posterior to the incisor teeth
What does the incisive foramen transmit?
Branches of the greater palatine blood vessels and nasopalatine nerve
Where is the inferior orbital fissure located?
Between the greater wing of the sphenoid and the maxilla
What are the two zygomatic bones commonly called?
Cheekbones
What do the zygomatic bones form?
The prominences of the cheeks and part of the lateral wall and floor of each orbit
With which bones do the zygomatic bones articulate?
The frontal, maxilla, sphenoid, and temporal bones
What does the temporal process of the zygomatic bone do?
Projects posteriorly and articulates with the zygomatic process of the temporal bone
What is formed by the articulation of the temporal process of the zygomatic bone and the zygomatic process of the temporal bone?
The zygomatic arch
is the largest and strongest facial bone.
mandible
What is the mandible also called?
Lower jawbone
What is the largest, strongest facial bone?
Mandible
What is the only movable skull bone (other than the auditory ossicles)?
Mandible
What are the parts of the mandible?
A curved, horizontal portion (body) and two perpendicular portions (rami)
What is the angle of the mandible?
The area where each ramus meets the body
What is the posterior condylar process of the mandible?
A structure that articulates with the mandibular fossa and articular tubercle of the temporal bone to form the temporomandibular joint (TMJ)
What is the anterior coronoid process of the mandible?
A structure to which the temporalis muscle attaches
What is the mandibular notch?
The depression between the coronoid and condylar processes
What is the alveolar process of the mandible?
The ridgelike arch containing the dental alveoli (sockets) for the mandibular (lower) teeth
Where is the mental foramen located?
Approximately inferior to the second premolar tooth
Why do dentists inject anesthetics near the mental foramen?
To reach the mental nerve
Where is the mandibular foramen located?
On the medial surface of each ramus
Why do dentists inject anesthetics near the mandibular foramen?
It is a common site for injecting anesthetics
What is the mandibular canal?
A canal that runs obliquely in the ramus and anteriorly to the body
What passes through the mandibular canal?
Inferior alveolar nerves and blood vessels
Where are the inferior alveolar nerves and blood vessels distributed?
To the mandibular teeth
hat is temporomandibular joint (TMJ) dysfunction also called?
TMJ syndrome and TMJ disorder
What are the symptoms of TMJ syndrome?
Dull pain around the ear, tenderness of the jaw muscles, a clicking or popping noise when opening or closing the mouth, limited or abnormal opening of the mouth, headache, tooth sensitivity, and abnormal wearing of the teeth
What can cause TMJ syndrome?
Improperly aligned teeth, grinding or clenching the teeth, trauma to the head and neck, or arthritis
What treatments are available for TMJ syndrome?
Application of moist heat or ice, limiting the diet to soft foods, administration of pain relievers such as aspirin, muscle retraining, use of a splint or bite plate to reduce clenching and teeth grinding (especially when worn at night), adjustment or reshaping of the teeth (orthodontic treatment), and surgery
In addition to the bones of the skull, the skull also contains oth er components:
the nasal septum, orbits, foramina, sutures, paranasal sinuses, and fontanels.
What is the nasal cavity?
A space inside the skull that is divided into right and left sides by a vertical partition called the nasal septum
What does the nasal septum consist of?
Bone and cartilage
What are the three components of the nasal septum?
The vomer, septal nasal cartilage, and the perpendicular plate of the ethmoid bone
What does the anterior border of the vomer articulate with?
The septal nasal cartilage
What type of cartilage is the septal nasal cartilage?
Hyaline cartilage
What does the superior border of the vomer articulate with?
The perpendicular plate of the ethmoid bone
What does the articulation of the superior border of the vomer and the perpendicular plate of the ethmoid bone form?
The remainder of the nasal septum
What does the term “broken nose” usually refer to?
Damage to the septal nasal cartilage rather than the nasal bones themselves
The structures that form the nasal septum are the
perpendicular plate of the ethmoid bone, the vomer, and septal nasal cartilage.
What is a deviated nasal septum?
One that does not run along the midline of the nasal cavity and deviates (bends) to one side
What can easily damage or break the nasal septum?
A blow to the nose
What happens when a broken nasal septum heals?
The bones and cartilage deviate to one side or the other
What can a deviated septum cause?
Block airflow into the constricted side of the nose, making it difficult to breathe through that half of the nasal cavity
Where does the deviation usually occur?
At the junction of the vomer bone with the septal nasal cartilage
What other cause, besides injury, can lead to a deviated septum?
Developmental abnormality
What can happen if the deviation is severe?
It may block the nasal passageway entirely
What can even a partial blockage lead to?
Infection
What can occur if inflammation happens due to a deviated septum?
Nasal congestion, blockage of the paranasal sinus openings, chronic sinusitis, headache, and nosebleeds
How can a deviated septum be treated?
It can usually be corrected or improved surgically
How many bones of the skull join to form each orbit (eye socket)?
Seven
What does the orbital cavity contain?
The eyeball and associated structures
What are the bones of the orbit?
Frontal, sphenoid, ethmoid, palatine, zygomatic, lacrimal, and maxilla
What shape does each orbit have?
Pyramid-shaped
What bones comprise the roof of the orbit?
Parts of the frontal and sphenoid bones
What bones form the lateral wall of the orbit?
Parts of the zygomatic and sphenoid bones
What bones make up the floor of the orbit?
Parts of the maxilla, zygomatic, and palatine bones
What bones form the medial wall of the orbit?
Parts of the maxilla, lacrimal, ethmoid, and sphenoid bones
How many major openings are associated with each orbit?
Five
Where is the optic canal located?
At the junction of the roof and medial wall
Where is the superior orbital fissure located?
At the superior lateral angle of the apex
Where is the inferior orbital fissure located?
At the junction of the lateral wall and floor
Where is the supraorbital foramen located?
On the medial side of the supraorbital margin of the frontal bone
Where is the lacrimal fossa located?
In the lacrimal bone
What are foramina?
Openings for blood vessels, nerves, or ligaments
What is the singular form of foramina?
Foramen
Where were most of the foramina and canals of the skull mentioned?
In the descriptions of the cranial cavity and facial bones
What systems of the body are important for studying foramina and canals?
Nervous and cardiovascular systems
The skull exhibits several unique features not seen in other bones of the body. These include
sutures, paranasal sinuses, and fontanels.
is a pyramid-shaped structure that contains the eyeball and associated structures.
Orbit
What is a suture?
An immovable fibrous joint (in most cases in an adult skull) that holds most skull bones together
Are sutures movable in infants and children?
Yes, they are often movable and function as important growth centers in the developing skull
What do the names of many sutures reflect?
The bones they unite
Where is the frontozygomatic suture located?
Between the frontal bone and the zygomatic bone
Where is the sphenoparietal suture located?
Between the sphenoid bone and the parietal bone
What does the coronal suture unite?
The frontal bone and both parietal bones
What does the sagittal suture unite?
The two parietal bones on the superior midline of the skull
Why is the sagittal suture named as such?
Because in the infant, before the bones of the skull are firmly united, the suture and the fontanels (soft spots) associated with it resemble an arrow
What does the lambdoid suture unite?
The two parietal bones to the occipital bone
Why is the lambdoid suture named as such?
Because of its resemblance to the capital Greek letter lambda (Λ)
Where may sutural bones occur?
Within the sagittal and lambdoid sutures
What do the two squamous sutures unite?
The parietal and temporal bones on the lateral aspects of the skull
Why is the squamous suture named as such?
Because “squam-“ means flat, like the flat overlapping scales of a snake
What are the paranasal sinuses?
Cavities within certain skull bones near the nasal cavity
Where are the paranasal sinuses most evident?
In a sagittal section of the skull
What are the paranasal sinuses lined with?
Mucous membranes that are continuous with the lining of the nasal cavity
Where do secretions produced by the mucous membranes of the paranasal sinuses drain?
Into the lateral wall of the nasal cavity
Are paranasal sinuses present at birth?
They are quite small or absent at birth
When do the paranasal sinuses increase in size?
During the eruption of the teeth and at the onset of puberty
How do the paranasal sinuses arise?
As outgrowths of the nasal mucosa that project into the surrounding bones
are mucous membrane–lined spaces in the frontal, sphenoid, ethmoid, and maxillary bones that connect to the nasal cavity.
Paranasal sinuses
Which skull bones contain the paranasal sinuses?
The frontal, sphenoid, ethmoid, and maxillae
How do the paranasal sinuses affect skull size?
They allow the skull to increase in size without a change in the mass (weight) of the bone
How do the paranasal sinuses affect nasal mucosa?
They increase the surface area of the nasal mucosa, thus increasing the production of mucus to help moisten and cleanse inhaled air
How do the paranasal sinuses affect sound?
They serve as resonating (echo) chambers within the skull that intensify and prolong sounds, enhancing the quality of the voice
How does a cold affect the paranasal sinuses?
The passageways through which sound travels into and out of the paranasal sinuses become blocked by excess mucus production, changing the quality of the voice
Where is the carotid canal located?
Petrous portion of temporal bone
What structures pass through the carotid canal?
Internal carotid artery, sympathetic nerves for eyes
Where is the hypoglossal canal located?
Superior to base of occipital condyles
What structures pass through the hypoglossal canal?
Hypoglossal (XII) nerve, branch of ascending pharyngeal blood vessel
Where is the infraorbital foramen located?
Inferior to orbit in maxilla
What structures pass through the infraorbital foramen?
Infraorbital nerve and blood vessels, branch of maxillary branch of trigeminal (V) nerve
Where is the jugular foramen located?
Posterior to carotid canal between petrous portion of temporal bone and occipital bone
What structures pass through the jugular foramen?
Internal jugular vein; glossopharyngeal (IX), vagus (X), and accessory (XI) nerves
Where is the foramen lacerum located?
Bounded anteriorly by sphenoid bone, posteriorly by petrous portion of temporal bone, medially by sphenoid and occipital bones
What structure passes through the foramen lacerum?
Branch of ascending pharyngeal artery
Where is the foramen magnum located?
Occipital bone
What structures pass through the foramen magnum?
Medulla oblongata and its membranes (meninges), accessory (XI) nerve, vertebral and spinal arteries
Where is the mandibular foramen located?
Medial surface of ramus of mandible
What structures pass through the mandibular foramen?
Inferior alveolar nerve and blood vessels
Where is the mastoid foramen located?
Posterior border of mastoid process of temporal bone
What structures pass through the mastoid foramen?
Emissary vein to transverse sinus, branch of occipital artery to dura mater
Where is the mental foramen located?
Inferior to second premolar tooth in mandible
What structures pass through the mental foramen?
Mental nerve and vessels
Where is the cribriform foramen located?
Cribriform plate of ethmoid bone
What structure passes through the cribriform foramen?
Olfactory (I) nerve
Where is the optic canal located?
Between superior and inferior portions of small wing of sphenoid bone
What structures pass through the optic canal?
Optic (II) nerve, ophthalmic blood vessels
Where is the foramen ovale located?
Greater wing of sphenoid bone
What structure passes through the foramen ovale?
Mandibular division of trigeminal (V) nerve
Where is the foramen rotundum located?
Junction of anterior and medial parts of sphenoid bone
What structure passes through the foramen rotundum?
Maxillary division of trigeminal (V) nerve
Where is the stylomastoid foramen located?
Between styloid and mastoid processes of temporal bone
What structures pass through the stylomastoid foramen?
Facial (VII) nerve, stylomastoid blood vessels
Where is the supraorbital foramen located?
Supraorbital margin of orbit in frontal bone
What structures pass through the supraorbital foramen?
Supraorbital nerve and blood vessels
