Anatomy ch.7

There are ____corresponding to the _______attached to them....

12 THORACIC VERTEBRAE(T1-T12); 12 pairs of ribs; no other vertebrae have ribs. Supports the thoracic cage enclosing the heart and lungs. Lacks transverse foramina and bifid processes. -spinous processes are relatively pointed and angle sharply downward. -body is somewhat heart-shaped -COSTAL FACETS for attachment of ribs -T1-T10 have TRANSVERSE COSTAL FACET at the end of each transverse process (provides a second point of articulation for ribs 1-10) Ribs insert between two vertebrae, the rib articulates with the INFERIOR COSTAL FACET of the upper vertebra and the SUPERIOR COSTAL FACET of the vertebra below that.

An __________is a cartilaginous pad...

INTERVERTEBRAL DISC; located between the bodies of two adjacent vertebrae. It consists of an inner gelatinous NUCLEUS PULPOSUS surrounded by a ring of fibrocartilage called ANULUS FIBROSUS There are 23 discs-the first one between cervical vertebrae 2 and 3 and the last one between the last lumbar vertebrae and the sacrum. The discs help to bind adjacent vertebrae together, enhance spinal flexibility, support the weight of the body, and absorb shock.

Whiplash often results from...

rear ended automobile collisions causing violent hypertension of the neck (backward jerking of the neck). This stretches or tears the ANTERIOR LONGITUDINAL LIGAMENT that courses along the front of the vertebral bodies, and it may fracture the vertebral body.

Many organs are named for their...

relationships to nearby bones.

The _______is the first vertebra that exhibits a...

axis, spinous process. In vertebrae C2-C6, the process is forked, or BIFID at its tip. This fork provides attachment for the NUCHAL LIGAMENT of the back of the neck.

Both the NEUROCRANIUM and VISCEROCRANIUM have regions of...

cartilaginous membranous origin.

The dislocation of one vertebra relative to the next can cause...

irreplaceable damage to the spinal cord.

At both the vertebral column exhibits...

one continuous C shaped curve, as it does in monkeys ,apes, and most other four-legged animals.

Herniated discs...

rarely occur in young people bc their discs are well hydrated and absorb pressure well. As people get older, the discs become dehydrated and they degenerate and grow thinner. After middle age however the anulus fibrosus becomes thicker and tougher, and the nucleus polposus is smaller, so disc herniations again become less common.

Anatomical features of the bone: Bones exhibit a variety of...

ridges, spines, bumps, depressions, canals, pores, slits, cavities, and articular surfaces often called bone-markings.

At birth the mandible consists of...

right and left bones joined medially by the MENTAL SYMPHYSIS (a zone of cartilage and fibrous connective tissue) the half's fuse in the first year and become fully united into a single bone by age 3. Deciduous (baby) teeth begin to erupt at about 7 months and continue through the second year; mandible widens to accommodate their roots. Permanent teeth replace deciduous teeth between 6-13

There are _______in the nasal cavity...

three conchae(facial bones); the superior and middle conchae are parts of the ethmoid bone. The INTERIOR NASAL CONCHA-is the largest of the three-and a separate bone.

We can view the skull as developing in ...

three major parts: the base, the calvaria, and the facial bones.

Ribs 8-...

12 are called FALSE RIBS bc they lack independent cartilaginous connections to the sternum. T11-T12 do not have tubercles and do not attach to the transverse processes of the vertebrae. They taper to a point and are called by a small cartilaginous tip, but there are no cartilaginous connections to the sternum or to any of the higher costal cartilages. The ribs are merely embedded in lumbar muscle at this end. Consequently 11 and 12 are also called FLOATING RIBS (among the Japanese and some other people, rib 10 is also usually a floating rib.

There are _____pairs of ribs.

12; with no difference in number between the sexes. Each is attached at its posterior (proximal) end to the vertebral column, and all but the last two arch around the flank of the chest and attach by way of cartilaginous strip, the COSTAL CARTILAGE, to the sternum.

All mammals have ____

7 cervical vertebrae-even the giraffe with its fantastically long neck.

About _______of disc herniations...

95%; occur at levels L4/L5 and L5/S1.

The most obvious feature of a vertebrae is the...

BODY or CENTRUM-a mass of spongy bone and red bone marrow covered with a thin shell of compact bone. (This is the weight-bearing portion of the vertebra) Posterior to the body of each vertebra is an ovoid to triangular space called the VERTEBRAL FORAMEN. Collectively, these foramen form the VERTEBRAL CANAL a passage for the spinal chord. The foramen is bordered by a bony VERTEBRAL ARCH (comprised of two parts on each side, a pillar-like PEDICLE and plate-like LAMINA) Extending from the apex of the arch, a projection called the SPINOUS PROCESS is directed toward the rear and downward. (can feel and see as a row of bumps along the spine) A TRANSVERSE PROCESS extends laterally from the point where the pedicle and lamina meet. The spinous and transverse processes provide points of attachment for spinal muscles and ligaments.

The ______are relatively small...

CERVICAL VERTEBRAE (C1-C7); Their Functions is to support the head and allow for its movements. C1 and C2 have unique structures for this purpose. Vertebra C1 is called the ATLAS bc it supports the head (like atlas in Greek mythology who was condemned to hold the heavens) It has no body and is little more than a delicate ring surrounding a large vertebral foramen. On each side is a LATERAL MASS with a deeply concave SUPERIOR ARTICULAR FACETS (which articulates with the occipital condyle of the skull; nodding yes these condyles rock back and forth on these facets) The INFERIOR ARTICULAR FACETS articulates with C2. The lateral masses are connected by an ANTERIOR ARCH and a POSTERIOR ARCH ( which bear slight protuberances called the ANTERIOR and POSTERIOR TUBERCLE, respectively) Vertebra C2 , the AXIS , allows rotation of the head as in gesturing "no". Distinctive feature is the prominent anterior knob called the DENS or ODONTOID PROCESS. (No other vertebra has a dens; begins as independent ossification center during first year of life fusses with axis by 3-6; projects into the vertebral foramen of the atlas, where it is held in blade by a TRANSVERSE LIGAMENT. The articulation between the atlas and the cranium is called the ATLANTO-OCCIPITAL JOINT; the articulation between the atlas and axis is called the ATLANTOAXIAL JOINT. All seven cervical vertebrae have a prominent round TRANSVERSE FORAMEN in each transverse process. These foramina provides passage and protection for the VERTEBRAL ARTERIES, which supply blood to the brain, and VERTEBRAL VEINS, which drain blood from various neck structures (but not the brain. Transverse foramina occur in no other vertebrae. C7 is a little different-it's spinous process is not bifid, but is long and forms a bump on the lower back of the neck. (Sometimes called the VERTEBRA PROMINENS).

Four (sometimes five) tiny _____fuse by the age of 20...

COCCYGEAL; to form the COCCYX. (Roman anatomist named it after the break of a cuckoo. It is colloquially called the tailbone (and is indeed the vestige of a tail) it provides attachment for muscles of the pelvic floor. Vertebra Co 1 has a pair of HORNS (CORNUA)- which serve as attachment points for ligaments that bind the coccyx to the sacrum. (Can be fractured by a difficult child both or a hard fall on the buttocks)

___________are those that enclose the brain;....

Cranial bones; collectively they compose the cranium (braincase). The delicate brain tissue does not come directly into contact with the cranial bones, but is separated from them by three membrane called meninges. (toughest is the dura meter).

A _______ is cracking of the anulus fibrosus of an...

HERNIATED (slipped or ruptured) DISC; intervertebral disc under strain, often caused by violent flexion of the vertebral column or by lifting heavy weights. Cracking of the anulus allows the gelatinous nucleus pulposus to ooze out (sometimes putting pressure on a spinal nerve root or the spinal chord) Back pain results from both pressure on the nervous tissue and inflammation stimulated by the nucleus polposus. The nucleus polposus usually escapes in a posterolateral direction, where the anulus is thinnest.

The _______form part of the medial wall of each orbit.

LACRIMAL BONES(facial bones); these are the smallest bones of the skull (size of a small fingernail). A depression called the LACRIMAL FOSSA houses a membranous LACRIMAL SAC (tears from the eyes collect in this sac and drain into the nasal cavity)

Most cranial fractures are...

LINEAR FRACTURES (elongated cracks) , which can radiate away from the point of impact. In a DEPRESSED FRACTURE, the cranium caves inward at the point of impact without breaking, but as the strain is distributed through the cranium, it can generate a fracture some distance away, even on the opposite side of the skull ( a contrafissura fracture).

There are five ______

LUMBAR VERTEBRAE (L1-L5) Thick stout body adapted for bearing weight of the upper body, and blunt, squarish spinous processes adapted for attachment of lumbar muscles. Superior processes face medially(like palms of hands about to clap) and the inferior processes face laterally, toward the superior processes of the next vertebrae (arranged to resist twisting of the lower spine)

At 5 weeks a developing thoracic vertebrae consists of...

a body of mesenchyme with a vertebral body, vertebral foramen, and a pair of wing-like lateral extensions called COSTAL PROCESSES. (which soon give rise to the ribs) At 6 weeks, a chondrification center develops at the base of each process. At 7 weeks, these centers begin to undergo endochondral ossification. A COSTOVERTEBRAL JOINT now appears at the base of the process, separating it from the vertebral body. By this time, the first seven ribs (true ribs) connect to the sternum by way of costal cartilages. An ossification center soon appears at the angle of the rib, and endochondral ossification proceeds from there to the distal end of the shaft. Secondary ossification centers appears in the timeline and head of the rib during adolescence.

The skull contains several prominent____, the largest with an adult volume of....

about 1300 ml, is the cranial cavity. Other cavities include: Orbits (eye sockets) Nasal cavity Paranasal sinuses Oral cavity (mouth or buccal cavity) Middle and Inner cavities

The base and calvaria of the skull...

are collectively called the NEUROCRANIUM (the cartilaginous neurocranium is also called the CHONDROCRANIUM) bc they enclose the brain.

Two small rectangular ________form the bridge of the...

NASAL BONES(facial bone); nose and support cartilages that shape the lower portion of the nose.

One of the universal characteristics of all chordates animals, including humans, is the...

NOTOCHORD, a flexible, middorsal rod of mesodermal tissue. Segments of embryonic mesoderm called SOMITES lie on each side of the notochord and neural tube. In week 4, part of each somite becomes a SCLEROTOME. This gives rise to vertebral cartilage, which is replaced by bone through endochondral ossification. The sclerotomes are temporarily separated by zones of looser mesenchyme. Each vertebral body arises from portions of two adjacent sclerotomes and the loose mesenchyme between them. The mid portion of each sclerotome gives rise to the anulus fibrosus of the intervertebral disc. The notochord degenerates and disappears in the regions of the developing vertebral bodies, but persists and expands between the vertebrae to form the nucleus pulposus of the intervertebral discs.

The cranial bones are separated at...

birth by gaps called FONTANELS, bridged by fibrous membranes. (permits the bones to shift as the infant squeezes through the birth canal, this shifting may deform the infants head but usually assumes a normal shape within a few days) Four of the fontanels are especially prominent and regular in location: ANTERIOR, POSTERIOR, SPHENOID and MASTOID FONTANELS(these close by intramembranous ossification) most close at 12 months, the largest -anterior fontanel- closes around 18-24 months, up to that age there is a soft spot.

The________forms the rear of the skull...

OCCIPITAL BONE; and much of its base. It's most conspicuous feature is the FORAMEM MAGNUM, where the spinal chord meets the brainstem. Severe swelling may force the brainstem out through the foramen magnum(fatal consequence). Occipital bone continued anterior to this as a thick median plate, the BASILAR PART. On each side of the foramen magnum is a smooth knob called the OCCIPITAL CONDYLE(where the skull rests on the vertebral column) beneath each condyle is a HYPOGLOSSAL CANAL(named for the hypoglossal nerve that passes through it to innervate the tongue muscles. In some people a CONDYLAR CANAL occurs posterior to each occipital condyle. Other features of the occipital bone can be palpated on the back of your head. One is a prominent median bill called the EXTERNAL OCCIPITAL PROTUBERANCE-the attachment for the NUCHAL LIGAMENT(which binds the skull to the vertebral column A ridge, the SUPERIOR NUCHAL LINE, can be traced horizontally from this protuberance towards the mastoid process. Defines the superior limit of the neck. The deeper INFERIOR NUCHAL LINE provides attachment for some of the deep neck muscles. This ridge can't be palpated on the living body but is visible on an isolated skull.

It is often said that there are 206...

bones in the skeleton, but this is only a typical adult count (not an invariable number). At birth there are about 270 and even more bones form during childhood. With age, the number of bones decreases as separate bones fuse. (Each side of child's pelvic girdle has three bones, but in adults they fuse into a single hip{coxal} bone on each side} The fusion of several bones, completed by adolescence to the mid 20s brings the average adult number of bones to 206.

The paranasal sinuses are named for the...

bones in which they occur; the frontal, ethmoid, sphenoid, and maxillary sinuses. These sinuses are connected with the nasal cavity, lined by a mucous membrane, and filled with air. They lighten the anterior portion of the skull and act as chambers that add resonance to the voice

The domed shape of the skull...

distributes the strain of most blows to the head and tends to minimize their effects. Hard blows can nevertheless fracture the calvaria

There are ___________cranial bones:

eight; 1 frontal bone 2 parietal bones 2 temporal bones 1 occipital bone 1 sphenoid bone 1 ethmoid bone

In addition to damaging brain tissue...

skull fractures can damage cranial nerves and meningeal blood vessels. (A break in a blood vessel may cause a hematoma{mass of clotted blood} that compresses the brain tissue,potentially leading to death within a few hours.)

To accumulate the growing brain, a child's...

skull grows more rapidly than the rest of the skeleton. 1/2 side by age 9 months, 3/4 by age 2, and nearly final size by 8-9. Children and babies heads are much larger in proportion to the trunk than that of adults.

The cranium is a rigid...

structure with an opening, the foramen magnum, where the spinal cord meets the brain. Consists of two major parts-calvaria and the base The calvaria (skullcap) is not a specific bone but simply the dome of the top of the head, composed of parts of multiple bones. Along the cut edge of the calvaria, you can also see the dipole (layer of spongy bone in the middle of the cranial bones)

The base(floor) of the cranial cavity...

which exhibits the depressions called cranial fosses. These correspond to the contour of the interior surface of the brain. The relatively shallow anterior cranial fossa is crescent-shaped and accommodates the frontal lobes of the brain. The middle cranial fossa which drops abruptly deeper, is shaped like a pair of outstretched bird wings and accommodate the temporal lobes. The posterior cranial fossa is deepest and houses a large posterior division of the brain called the cerebellum

The _____are located in the posterior nasal cavity...

PALATINE BONES(facial bone) Each one has an L shape formed by HORIZONTAL PLATE and PERPENDICULAR PLATE. Each is marked by a large GREATER PALATINE FORAMEN(a nerve passage to the palate).

The _______forms the inferior portion of the nasal septum...

VOMER(facial bone); it's name literally means "plowshare" which refers to its resemblance to the blade of a plow. The superior half of the nasal septum is formed by the perpendicular plate of the ethmoid bone. The vomer and perpendicular plate support a wall of septal cartilage that forms most of the anterior part of the septum.

The_______ colloquially called the....

ZYGOMATIC BONES(facial bone); cheekbones, form the angles of the cheek. Each zygomatic bone has an inverted T shape and small ZYGOMATICOFACIAL FORAMEN. The prominent zygomatic arch that flares from each side of the skull is formed by the union of the zygomatic bone, temporal bone and maxilla

Facial trauma can produce...

linear LE FORT FRACTURES, which predictably follow lines of weakness in the facial bones. Type II lie fort fracture separates the entire central region of the face from the rest of the skull.

The sternum begins as a pair of...

longitudinal strips of mesenchyme called the STERNAL BARS. These form initially in the anterolateral body wall and migrate medially during chondrification. The right and left sternal bars begin to fuse in week 7 as the most superior ribs contact them. Fusion of the sternal bars progresses downward, ending with the formation of the xphoid process in week 9. The sternal bars form by endochondral ossification beginning superiorly and progressing toward the xiphoid. Ossification begins in month 5 and is completed shortly after birth. (in some cases, the sternal bars fail to fuse completely at the inferior end, so the infant xiphoid process is forked is perforated)

Beyond the tubercle, each rib...

makes a sharp curve around the side of the chest and then progresses anteriorly to approach the sternum. The curve is called the ANGLE of the rib and the rest of the bony blade distal to it is called the shaft. The inferior margin of the shaft has a COSTAL GROOVE that marks the path of the intercostal blood vessels and nerve.(each of these ribs, like rib 1, ends in a blunt, rough area where the costal cartilage begins. Each has its own costal cartilage connecting it to the sternum; bc of this feature, ribs 1-7 are called TRUE RIBS

Efficient bipedal locomotion is possible only bc...

of several adaptations of the feet, legs, vertebral column and skull. The human head is balanced on the vertebral column with the gaze directed forward. The foramen magnum moved to a more inferior location and the face is much flatter than an apes, so there is less weight anterior to the ociptical condyles and the head has less tendency to tip forward.

The right and left ______

parietal bones form most of the cranial root and part of its walls. Each is bordered by four sutures that join it to the neighboring bones: 1-The sagital suture between the parietal bones 2-The coronal suture at the anterior margin 3-The lamboid suture at the posterior margin 4-The squamous suture laterally Small sutural (wormian) bones are often seen along the sagittal and lamboid sutures. A parietal foramen sometimes occurs near the corner of the lamboid and sagittal sutures. A pair of slight thickenings, the superior and inferior temporal lines, forms an arc across the parietal and frontal bones. The temporal lines mark the attachment of the large temporalis muscle, a chewing muscle.

The base of the cranium develops from...

several pairs of cartilaginous plates. They give rise to most parts of the sphenoid, ethmoid, temporal, and occipital bones. The flat bones of the calvaria form, in contrast, by the intramembranous method. The facial bones are built around cartilages but develop by the intramembranous process.

The _______is the most complex part of the skeleton.

skull

The THORACIC CAGE consists of the...

thoracic vertebrae, sternum and ribs. It's inferior border is the arc of the lower ribs, called the COSTAL MARGIN. Protects the thoracic cage but also the spleen, most of the liver, and to some extent the kidneys. Most important is its role in breathing, it is rhythmically expanded by the respiratory muscles to create a vacuum that draws air into the lungs, and then compressed to expel air.

The skeleton is divided into...

two regions: axial and appendicular. The axial skeleton, forms the central supporting axis of the body and includes the skull, vertebral column, ribs, and sternum. The appendicular skeleton includes the bones of the upper limb and pectoral girdle, and bones of the lower limb and pelvic girdle.

The number of bones...

varies among adults. One reason is the development of sesamoid bones-bones that form within certain tendons in response to stress. (The platella {kneecap} is the largest of these, most of the others are small, rounded bones in the hands and feet. Another reason for adult variation is that some people have extra bones in the skill called sutural (or wormian) bones.

The_________is an anterior cranial bone located...

ETHMOID BONE; between the eyes. It contributes to the medial wall of the orbit, the roof and walls of the nasal cavity, and the nasal septum. Very porous and delicate bone w/three major portions: 1-the vertical PERPENDICULAR PLATE, a thin median plate that forms 2/3 of the nasal septum(the lower part is formed by cartilages and the vomer, septum is curved, or deviated toward one nasal fossa or the other). The septum divides the NASAL FOSSAE 2-a horizontal CRIBRIFORM PLATE, which forms the roof of the nasal cavity. Has a median crest called the CRISTA GALLI(an attachment point for the dura meter). On each side of the crista is an area perforated with numerous holes, the CRIBRIFORM (olfactory) FORAMINA.(a pair of olfactory bulbs of the brain, concerned with the sense of small rests in these depressions , and the foramina allow passage for olfactory nerve's from the nasal cavity to the bulbs. 3-the LABYRINTH, a large mass on each side of the perpendicular plate. Named for the fact that internally it has a maze of air sacs called the ETHMOID CELLS. (collectively these constitute the ethmoid sinus). The lateral surface of the labyrinth is a smooth slightly concave ORBITAL PLATE. The medial surface of the labyrinth gives rise to two curled, scroll-like plates of bone called the SUPERIOR and MIDDLE NASAL CONCHAE or TURBINATES. There is also a separate inferior nasal conchae. The the concert occupy most of the space in the nasal cavity. By filling space and creating turbulence in the flow of inhaled air, ensuring that air contacts the mucous membranes that cover these bones. The superior conchae and adjacent part of the nasal septum also bear the sensory cells of smell.

The axial skeleton develops primarily by...

Endochondral ossification. This is a two step process: 1-CHONDRIFICATION, in which embryonic mesenchyme condenses and differentiates into hyaline cartilage; and 2-OSSIFICATION, in which the cartilage is replaced by bone.

________do not enclose the brain but....

FACIAL BONES; lie anterior to the cranial cavity. They support the orbital, nasal, and oral cavities; gone shape to face; and provides attachment for the muscles of facial expressions and mastication. There are 14 facial bones: 2 maxillae 2 palatine bones 2 zygomatic bones 2 lacrimal bones 2 nasal bones 2 inferior nasal conchae 1 vomer 1 mandible

The _________is the strongest bone of the skull...

MANDIBLE; and the only part that can move significantly. Supports the lower teeth and provides attachment for muscles of mastication and facial expressions. The horizontal portion bearing the teeth, of called the BODY; the vertical to oblique posterior portion is the RAMUS(plural rami) and these two portions meet at a corner called the ANGLE. The point of the chin is the MENTAL PROTUBERANCE. Inner posterior surface has a pair of small points, the MENTAL SPINES(serves for attachment of chin muscles). MENTAL FORAMEN (anterolateral surface of the body) permits passage of nerves and blood vessels of the chin. The angle of the mandible has a rough lateral surface for insertion of the MASSETER(a muscle for mastication) Like the maxilla, the mandible has pointed ALVEOLAR PROCESSES between the teeth. The ramus is somewhat Y shaped. Its posterior branch, called the CONDYLAR PROCESS, bears the MANDIBULAR CONDYLE (an oval knob that articulates with the mandibular fossa of the temporal bone). This articulation is the jaw joint, or TEMPOROMANDIBULAR JOINT(TMJ). The anterior branch of the ramus is a blade called the CORONOID PROCESS(it serves for the for insertion of the temporalis muscle, which pulls the mandible upward when you bite). The U shaped arch between the two processes is called the MANDIBULAR NOTCH. Just below the notch, on the medial surface of the ramus is the MANDIBULAR FORAMEN( a passage for a nerve and blood vessels that enter the bone here to reach the lower teeth.)

The______are the largest...

MAXILLAE; facial bones. They form the upper jaw and meet each other at a median INTERMAXILLARY SUTURE. Small points of maxillary bone called ALVEOLAR PROCESSES grow into the spaces between the base of the teeth. The root of each tooth is inserted into a deep socket or ALVEOLUS. (Teeth are not bones). Each maxilla extends from the teeth upward to the inferomedial wall of the orbit. Just below the orbit is an INFRAORBITAL FORAMEN. The maxilla forms part of the floor of the orbit, where it exhibits a gash called the INFERIOR ORBITAL FISSURE that angles downward and medially(passage for blood vessels and sensory nerves from the face). The interior and superior orbital fissures form a sideways V. The PALATE forms the root of the mouth and floor of the nasal cavity. Consists of a bony HARD PALATE in front and a fleshy SOFT PALATE in the rear. Most of the hard palate is formed by horizontal extensions of the maxillae called PALATINE PROCESSES. Just behind the incisors (front teeth) is a pair of incisive foramina.

_______surrounding the neural tube condenses and forms the vertebral arches of the vertebrae...

Mesenchyme; Approaching the end of the embryonic stage, the mesenchyme of scerlotomes forms the cartilaginous forerunners of the vertebral bodies. The two halves of the arch fuse with each other and with the body, the spinous and traverse processes grow outward from the arch. Thus, a complete cartilaginous vertebral column is established. Ossification of the vertebrae begins during the embryonic period but is not completed until age 25. Each vertebrae develops the primary ossification centers: one in the body and one in each half of the vertebral arch. At birth these three bony parts are still connected by hyaline cartilage. The two halves of the arch finish ossifying and fuse and 3-5. The attachment of the arch to the body remain cartilaginous for awhile until 3-6. Secondary ossification centers form in puberty at the tips of the spinous and transverse processes and in a ring encircling the body. They unite with the rest of the vertebrae by age 25.

An understanding of how the muscles produce body movements also depends on...

knowledge of skeletal anatomy.

The _________has a complex shape with a thick median....

SPHENOID BONE; BODY(contains a pair of sphenoid sinuses and has a saddle-like surface feature named the SELLA TURCICA{consists of a deep pit called the HYPOPHYSEAL FOSSA}; a raised anterior margin called the tuberculum sellae, posterior margin the dorsum sellae) and outstretched GREATER and LESSER WINGS(give bone a ragged moth-like shape). The lesser wing forms the posterior wall of the orbit and contains the OPTIC CANAL(which permits passage of the optic nerve and ophthalmic artery. Superiorly, a pair of bony spines of the lesser wing called the ANTERIOR CLINOID PROCESSES appears to guard optic foramina. A gash in the posterior wall of the orbit, the SUPERIOR ORBITAL FISSURE, angles upward lateral to the optic canal. (serves as a passage for three nerves that supply the muscles of eye movement Lateral to the sella turcica, the sphenoid is perforated by several foramina. The FORAMEN ROTUNDUM and FORAMEN OVALE are passages for two branches of the trigeminal nerve. The FORAMEN SPINOSUM(provides passage for an artery of the meninges). An irregular gash called the FORAMEN LACERUM. Lateral to each aperture there are a pair of parallel plates- the MEDIAL and LATERAL PTERYGOID PLATES. (each plate has a narrow inferior extension called the PTERYGOID PROCESS). The plates provide attachment for some of the chewing muscles.

The ______ is a bony plate anterior to the heart...

STERNUM(breastbone). It is subdivided into three regions: the MANUBRIUM, BODY and XIPHOID PROCESS. The MANUBRIUM is the broad superior portion shaped like the knot in a tie. Lies at the level of vertebrae T3 to T4. (It has a median SUPRASTERNAL NOTCH, and right and left CLAVICULAR NOTCHES where it articulates with the clavicles. The sword-like BODY, or GLADIOLUS is the longest part of the sternum, lying at the level of vertebrae T5 through T9. It joins the MANUBRIUM at the STERNAL ANGLE.(in some people the sternal is rounded or concave, the second rib attaches here. At the inferior end is a small, dagger-like XIPHOID PROCESS(at the level of vertebrae T10 to T11. , it provides attachment for some abdominal muscles. In cardiopulmonary resuscitation (cpr) improperly performed chest compression can drive the XIPHOID process into the liver and caused a fatal hemorrhage.

A pair of ______project upward from one vertebrae and...

SUPERIOR ARTICULAR PROCESSES; meet a similar pair of INFERIOR ARTICULAR PROCESSES that project downward from the vertebrae above (each process has a flat articular surface {facet} facing that of the adjacent vertebrae, which restrict twisting of the vertebral column) Where two vertebrae are joined, they exhibit an opening between their pedicles called the INTERVERTEBRAL FORAMEN ( this allows for passage of spinal nerves that connect with the spinal chord at regular intervals; each foramen is formed by an INFERIOR VERTEBRAL NOTCH in the pedicle of the superior vertebra and a SUPERIOR VERTEBRAL NOTCH in the pedicle of the one below it.

_________ are closely associated with the skull but are not considered part of it....

Seven bones; three auditory ossicles in each middle-ear cavity and the hyoid bone beneath the chin. The AUDITORY OSSICLES: MALLEUS(hammer), INCUS(anvil), and STAPES(stirrup). The HYOID BONE is a slender U shaped bone between the chin and larxyn. (One of the few bones that does not articulate with any other; it is suspended like a hammock, by the small styloid muscles and styloid ligaments.) the medial BODY of the hyoid is flanked on either sides by projections called the GREATER and LESSER HORNS. The larynx (voice box) is suspended from the hyoid bone by a broad ligament and the hyoid serves also for attachment of several muscles that control the larynx, mandible, and tongue. (Forensic pathologists look for a fracture hyoid as evidence of strangulation)

Beyond the age of three years the vertebral column is...

Slightly S shaped, with four bends called the CERVICAL, THORACIC, LUMBAR, and PELVIC CURVATURES. The thoracic and pelvic curvatures are called PRIMARY CURVATURES bc they are present at birth, when the spine has a single C shaped curvature. The cervical and lumbar curvatures are called SECONDARY CURVATURES bc they develop later, in the child's first few years of crawling and walking. The resulting S shape makes sustained bipedal walking possible.

Injury to the cervical vertebrae (a broken neck) often result from violent blows to the head....

Such injuries often crush the body or arches of a vertebra or cause one vertebra to slip forward.

The ________of a child begin to fuse around age 16....

five SACRAL VERTEBRAE (S1-S5); and by age 26 they are usually fused into a single bony plate, the SACRUM( forms the posterior wall of the pelvic cavity and protects the organs within; named for prominence and strongest bone in the vertebral column) It's anterior surface is smooth and concave and has four transverse lines (that indicate where the five vertebrae have fused ). This surface exhibits four pairs of large ANTERIOR SACRAL (PELVIC) FORAMINA (which allow the passage of nerves and arteries to the pelvic organs. The posterior surface of the sacrum is very rough. The spinous processes of the vertebrae fuse into a posterior ridge called the MEDIAN SACRAL CREST. The transverse processes fuse into a less prominent LATERAL SACRAL CREST on each side of the median crest. POSTERIOR SACRAL FORAMINA present of posterior side of sacrum. A SACRAL CANAL runs through the sacrum and ends in an inferior opening called the SACRAL HIATUS.(this canal contains spinal nerve roots in life) On each side of the sacrum is an ear-shaped AURICULAR SURFACE. (this articulates with a similarly shaped surface on the hip bone and forms the strong nearly immovable SACOILIAC JOINT. The body of vertebra S1 kid anteriorly to form a SACRAL PROMONTORY (which supports the body of vertebra L5) Lateral to the median sacral crest S1 also has a pair of SUPERIOR ARTICULAR PROCESSES(that articulate with L5. Lateral to these are a pair of large, rough, wing-like extensions called the ALAE.

The face of a newborn is...

flat and small compared to the large cranium. The face enlarges as the mandible, teeth, and paranasal sinuses develop.

Bones of the skull have especially conspicuous...

foramina-holes that allow passage for nerve and blood vessels.

The ________extends from the forehead back to a prominent....

frontal bone; coronal suture, with crosses the crown of the head from right to left and joins the frontal bone to the parietal bones. Forms the anterior wall and about one-third of the roof of the cranial cavity. Deep to the eyebrows it has a ridge called the supraorbital margin. The center of each margin is perforated by a single supraorbital foramen, which provides passage for a nerve, artery and vein. The smooth area of the frontal bone just above the root of the nose is called the glabella.

As a rule, the ribs...

increase in length from 1-7 and become progressively smaller again through rib 12. They are increasingly oblique (slanted in orientation) from 1-9, then less so from 10-12. Rib 1 is peculiar. Much of this rib lies above the level of the clavicle. It is a short, flat, C shaped plate of bone. At the vertebral end it exhibits a knobby HEAD that articulates with the body of vertebra T1. The rib narrows to a NECK and then widens again to form a rough area called the TUBERCLE. The rib then flattens and widens into a gently sloping blade-like SHAFT.(has a groove on the superior surface that serves as a platform for two blood vessels called the SUBCLAVIAN ARTERY and VEIN. Ribs 2-7 are more topical in appearance (at the proximal end each exhibits a head, neck and tubercle. The head is wedge-shaped and inserted between two vertebrae ( each Martin has a smooth surface called an ARTICULAR FACET. The SUPERIOR ARTICULAR FACET joins the inferior costal facet of the vertebrae above; the INFERIOR ARTICULAR FACET joins the superior costal facet of the vertebrae below. The tubercle of the rib articulates with the transverse costal facet of each same-numbered vertebra.

Most of the bones in the skull are rigidly...

joined by sutures, joints that appear as seams on the cranial surface.

The VERTEBRAL COLUMN(spine) physically...

supports the skull and trunk, allows for their movement, protects the spinal chord, and absorbs stresses produced by walking, running and lifting. Also provides attachment for the limbs, thoracic cage, and postural muscles. Although commonly called the backbone, it consists not of a single bone but a chain of 33 VERTEBRAE with INTERVERTEBRAL DISCS of fibrocartilage between most of them. The adult vertebral column averages about 71 cm(28 inches), with 23 intervertebral discs accounting for 1/4 of the length. Most people are about 1%shorter when they go to bed. Bc in the day the weight of the body compressed the intervertebral discs and squeezed water out of them. When sleeping with the weight off the spine, the discs reabsorb water and swell. The vertebrae are divided into five groups: 7 cervical vertebrae in the neck; 12 thoracic vertebrae in the chest; 5 lumbar vertebrae in the lower back; 5 sacral vertebrae at the base of the spine; and 4 tiny coccygeal vertebrae. Think 7-12-5 day to remember. Variations in this arrangement occur in about 1 in 20.

Just above and anterior to the ear is the...

temporal bone, which forms the lower wall and part of the floor of the cranial cavity. Derives it's name from the fact that people often develop their first grey hairs on the temples. Four parts: 1-SQUAMOUS PART is relatively flat and vertical. It is encircled by the squamous suture. It bears two prominent features: a) the ZYGOMATIC PROCESS, which extends anteriorly to form part of the ZYGOMATIC ARCH(cheekbone); and b) the MANDIBULAR FOSSA, a depression where the mandible articulates with the cranium. 2-TYMPANIC PART is a small plate of bone that borders the opening of the EXTERNAL ACOUSTIC MEATUS, the ear canal. It has a pointed spine on its inferior surface, the STYLOID PROCESS(named after Ancient Greek and Roman writing stylus; provides attachment for muscles of the tongue, pharynx, and hyoid bone. 3-the MASTOID PART lies posterior to the tympanic part. It bears a heavy MASTOID PROCESS, which can palpate as a prominent lump behind the earlobe. Filled with air sinuses that communicate with the middle-ear cavity(which are subject to infection and inflammation, which can erode the bone and spread to the brain). There is then a MASTOID NOTCH, medial to the mastoid process. It is the origin of the DIGASTRIC MUSCLE, a muscle that opens the mouth. The notch is perforated by the STYLOMASTOID FORAMEN at its anterior end and the MASTOID FORAMEN at its posterior end. 4-the PETROUS PART can be seen in the cranial floor, where it resembles a little mountain range separating the middle cranial fossa from the posterior fossa. It houses the middle and inner ear cavities. The INTERNAL ACOUSTIC MEATUS opens on its posterior medial surface; this canal is the passage for the VESTIBULOCHLEAR NERVE(which carries sensations of hearing and balance from the inner ear to the brain.) Two prominent foramina named for the major blood vessels that pass through them: CAROTID CANAL(passage for the internal carotid artery a major blood supply to brain); JUGULAR FORAMEN large irregular opening just medial to the styloid process, blood from the brain drains through this foramen into the internal jugular vein of the neck. Three cranial nerves also pass through this foramen.

The facial skeleton is called...

the VISCEROCRANIUM bc it develops from the pharyngeal(visceral) arches.