CH 8 - The Skeletal System
The right and left parietal bones form most of the cranial roof and part of its walls. Each is bordered by four sutures that join it to the neighboring bones:
(1) a sagittal suture between the parietal bones; (2) the coronal suture at the anterior margin; (3) the lambdoid suture at the posterior margin; and (4) the squamous suture laterally.
Small points of maxillary bone called (X) grow into the spaces between the bases of the teeth. The root of each tooth is inserted into a deep socket, or (Y)
(X) - alveolar processes (Y) - alveolus
There are eight cranial bones:
1 frontal bone 1 occipital bone 2 parietal bones 1 sphenoid bone 2 temporal bones 1 ethmoid bone
The most complex region of the scapula is its lateral angle, which has three main features:
1. The acromion is a plate like extension of the scapular spine that forms the apex of the shoulder. It articulates with the clavicle, which forms the sole bridge from the appendicular to the axial skeleton. 2. The coracoid process is named for a vague resemblance to a crow's beak, but is shaped more like a bent finger; it provides attachment for tendons of the biceps brachii and other muscles of the arm. 3. The glenoid cavity is a shallow socket that articulates with the head of the humerus, forming the glenohumeral joint.
Each upper limb contains 30 bones distributed in the following regions.
1. The arm proper (brachial region or brachium) extends from shoulder to elbow. It contains only one bone, the humerus. 2. The forearm (antebrachial region or antebrachium) extends from elbow to wrist and contains two bones: the radius and ulna. In anatomical position, these bones are parallel and the radius is lateral to the ulna. 3. The hand consists of the carpal region, with 8 small carpal bones arranged in two rows in the base of the hand; the metacarpal region in the palm, with 5 bones; and the fingers (digits), with 14 bones. The two hands together contain over one-quarter of all the bones in the body.
Each lower limb has 30 bones distributed in the following regions.
1. The thigh (femoral region) extends from hip to knee and contains the femur. The patella (kneecap) is a sesamoid bone at the junction of the femoral and crural regions. 2. The leg proper (crural region) extends from knee to ankle and contains two bones, the medial tibia and lateral fibula. 3. The foot consists of the tarsal region, with 7 tarsal bones extending from the heel to the midpoint of the foot arch; metatarsal region, with 5 bones extending from there to the "balls" of the feet just proximal to the toes; and toes (digits), with 14 bones. The feet and hands together contain more than half of all the body's bones (106 of the total 206).
The distal end of the radius has the following features, from lateral to medial:
1. a bony point, the styloid process, which can be palpated proximal to the thumb; 2. two shallow depressions (articular facets) that articulate with the scaphoid and lunate bones of the wrist; and 3. the ulnar notch, which articulates with the end of the ulna.
support the orbital, nasal, and oral cavities, shape the face, and provide attachment for the muscles of facial expression and mastication. There are 14 facial bones:
2 maxillae 2 nasal bones 2 palatine bones 2 inferior nasal conchae 2 zygomatic bones 1 vomer 2 lacrimal bones 1 mandible
The vertebral column has how many vertebrae?
33 vertebrae with intervertebral discs
There are (X) lumbar vertebrae (L1-L5). Their most distinctive features are a thick, stout body and a blunt, squarish spinous process for attachment of the strong lumbar muscles
5 - In addition, their articular processes are oriented differently than on other vertebrae. The superior processes face medially (like the palms of your hands about to clap), and the inferior processes face laterally, toward the superior processes of the next vertebra.
The vertebrae are divided into five groups, usually numbering
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
The ethmoid bone contributes to the medial wall of the orbit, the roof and walls of the nasal cavity, and the nasal septum. It is a very porous and delicate bone, with three major portions - 2
A horizontal cribriform plate, which forms the roof of the nasal cavity. This plate has a median blade called the crista galli, an attachment point for the dura mater. On each side of the crista is an elongated depressed area perforated with numerous holes, the cribriform (olfactory) foramina. A pair of olfactory bulbs of the brain, concerned with the sense of smell, rests in these depressions, and the foramina allow passage for olfactory nerves from the nasal cavity to the bulbs
Axial skeleton - cranial and facial bones (22 bones)
CRANIAL BONES Frontal bone (1) Temporal bones (2) Parietal bones (2) Sphenoid bone (1) Occipital bone (1) Ethmoid bones (2) FACIAL BONES Maxillae (2) Nasal bones (2) Palatine bones (2) Vomer (1) Zygomatic bones (2) Inferior nasal conchae (2) Lacrimal bones (2) Mandible (1)
Axial skeleton - vertebral column (33 bones)
Cervical vertebrae (7) Sacrum (5) Thoracic vertebrae (12) Coccyx (4) Lumbar vertebrae (5)
Appendicular skeleton - lower limbs (60 bones)
Femurs (2) Tarsal bones (14) Patellae (2) Metatarsal bones (10) Tibiae (2) Phalanges (28) Fibulae (2)
(X) tiny coccygeal vertebrae (Co1 to Co4 or Co5) fuse by the age of 20 to 30 years to form the coccyx colloquially called the tailbone.
Four (sometimes five)
Appendicular skeleton - Pelvic girdle (2 bones)
Hip bones (2)
Appendicular skeleton - Upper limbs (60 bones)
Humerus (2) Carpal bones (16) Radius (2) Metacarpal bones (10) Ulna (2) Phalanges (28)
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Occipital Bone - Hypoglossal canal
Hypoglossal nerve to muscles of tongue
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Mandible - Mandibular foramen
Inferior alveolar nerves and vessels to the lower teeth
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Maxilla - Infraorbital foramen
Infraorbital nerve and vessels
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Maxilla - Inferior orbital fissure
Infraorbital nerve; zygomatic nerve; infraorbital vessels
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Temporal Bone - Carotid canal
Internal carotid artery
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Temporal Bone - Jugular foramen
Internal jugular vein; glossopharyngeal, vagus, and accessory nerves
Axial skeleton - auditory ossicles (6)
Malleus (2) Stapes (2) Incus (2)
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Sphenoid Bone - Foramen ovale
Mandibular division of trigeminal nerve; accessory meningeal artery
Axial skeleton - facial bones
Maxillae (2) Nasal bones (2) Palatine bones (2) Vomer (1) Zygomatic bones (2) Inferior nasal conchae (2) Lacrimal bones (2) Mandible (1)
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Sphenoid Bone - Foramen rotundum
Maxillary division of trigeminal nerve
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Mandible - Mental foramen
Mental nerve and vessels
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Sphenoid Bone - Superior orbital fissure
Oculomotor, trochlear, and abducens nerves; ophthalmic division of trigeminal nerve; ophthalmic veins
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Sphenoid Bone - Optic canal
Optic nerve; ophthalmic artery
Axial skeleton - Thoracic cage (25 bones plus thoracic vertebrae)
Ribs (24) Sternum (1)
Appendicular skeleton - Pectoral girdle (4 bones)
Scapulae (2) Clavicles (2)
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them -Temporal Bone - external acoustic meatus
Sound waves to eardrum
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Occipital Bone - Foramen magnum
Spinal cord; accessory nerve; vertebral arteries
Foramina of the Skull and the Nerves and Blood Vessels Transmitted Through Them - Frontal Bone - Supraorbital foramen or notch
Supraorbital nerve, artery, and vein; ophthalmic nerve
functions of thoracic cage
The cage protects not only the thoracic organs 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.
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, about the diameter of a pencil lead, provides passage for an artery of the meninges.
The ethmoid bone contributes to the medial wall of the orbit, the roof and walls of the nasal cavity, and the nasal septum. It is a very porous and delicate bone, with three major portions - 3
The labyrinth, a large mass on each side of the perpendicular plate. The labyrinth is named for the fact that internally, it has a maze of air spaces called the ethmoidal cells. Collectively, these constitute the ethmoid sinus discussed earlier. The lateral surface of the labyrinth is a smooth, slightly concave orbital plate seen on the medial wall of the orbit. The medial surface of the labyrinth gives rise to two curled, scroll-like plates of bone called the superior and middle nasal conchae. These project into the nasal fossa from its lateral wall toward the septum. There is also a separate bone, the inferior nasal concha, discussed later. The three conchae occupy most of the nasal cavity, leaving little open space. By filling space and creating turbulence in the flow of inhaled air, they ensure that the air contacts the mucous membranes that cover these bones, which cleanse, humidify, and warm the inhaled air before it reaches the lungs. The superior concha and adjacent part of the nasal septum also bear the sensory cells of smell.
This forms the rear of the skull (occiput) and much of its base
The occipital bone
This forms the roof of the mouth and floor of the nasal cavity. Its function is to separate the nasal cavity from the oral cavity, enabling us (and other mammals) to continue breathing while chewing.
The palate
The distal end of the humerus also shows three deep pits: two anterior and one posterior.
The posterior pit, called the olecranon fossa, accommodates a process of the ulna called the olecranon when the elbow is extended. On the anterior surface, a medial pit called the coronoid fossa accommodates the coronoid process of the ulna when the forearm is flexed. The lateral pit is the radial fossa, named for the nearby head of the radius.
This has a complex shape with a thick median body and outstretched greater and lesser wings, which give the bone as a whole a ragged mothlike shape.
The sphenoid bone
The relatively complex shape of the temporal bone is best understood by dividing it into four parts:
The squamous part, the tympanic part, the mastoid part, and the petrous part
(X) consists of the thoracic vertebrae, sternum, and ribs.
The thoracic cage - It forms a roughly conical enclosure for the lungs and heart and provides attachment for the pectoral girdle and upper limb.
The three sides and angles of the scapula
The three sides of the triangle are called the superior, medial (vertebral), and lateral (axillary) borders, and its three angles are the superior, inferior, and lateral angles.
The ethmoid bone contributes to the medial wall of the orbit, the roof and walls of the nasal cavity, and the nasal septum. It is a very porous and delicate bone, with three major portions - 1
The vertical perpendicular plate, a thin median plate of bone that forms the superior two-thirds of the nasal septum. The septum divides the nasal cavity into right and left air spaces called the nasal fossae. The septum is often curved, or deviated, toward one nasal fossa or the other.
How many intervertebral discs are there?
There are 23 discs—the first one between cervical vertebrae 2 and 3 and the last one between the last lumbar vertebra and the sacrum. They help to bind adjacent vertebrae together, support the weight of the body, and absorb shock.
The articulation between the atlas and the cranium is called the (X); the one between the atlas and axis is called the (Y)
X = atlanto-occipital joint Y = atlantoaxial joint.
The mandible - The horizontal portion, bearing the teeth, is called the (X); the vertical to oblique posterior portion is the (Y); and these two portions meet at a corner called the (Z)
X = body Y = ramus Z = angle
The largest tarsal bone is the (X), which forms the heel. Its posterior end is the point of attachment for the (Y) from the calf muscles.
X = calcaneus Y = calcaneal (Achilles) tendon
The distal end of the humerus has two smooth condyles. The lateral one, called the (X), is shaped like a wide tire and articulates with the radius. The medial one, called the (Y), is pulleylike and articulates with the ulna.
X = capitulum Y = trochlea
An intervertebral disc is a cartilaginous pad located between the bodies of two adjacent vertebrae. It consists of an inner gelatinous (X) surrounded by a ring of fibrocartilage, the (Y)
X = nucleus pulposus Y = anulus fibrosus
A sacral canal runs through the sacrum and ends in an inferior opening called the (X). This canal contains spinal nerve roots. On each side of the sacrum is an ear shaped region called the (Y)
X = sacral hiatus Y = auricular surface
The medial end of the clavicle articulates with the sternum at the (X), and its lateral end articulates with the scapula at the (Y)
X = sternoclavicular joint Y = acromioclavicular joint
The palate consists of
a bony hard palate anteriorly and a fleshy soft palate posteriorly.
What is a masseter?
a muscle of mastication.
Each foramen is bordered by a bony vertebral arch composed of two parts on each side:
a pillar like pedicle and plate like lamina.
Each side of a child's pelvic girdle has three bones—the ilium, ischium, and pubis—but in adults, these are fused into
a single hip bone on each side.
The leg has two bones:
a thick strong tibia on the medial side and a slender fibula on the lateral side
The (X) is a plate like extension of the scapular spine that forms the apex of the shoulder. It articulates with the clavicle, which forms the sole bridge from the appendicular to the axial skeleton.
acromion
Lateral to the median sacral crest, S1 also has a pair of superior articular processes that articulate with vertebra L5. Lateral to these is a pair of large, rough, wing like extensions called the (X)
alae
Anatomical Features (Markings) of Bones - A pit or socket (tooth socket)
alveolus
The smooth surface of the humerus head (covered with articular cartilage in the living state) is bordered by a groove called the
anatomical neck
Dried bones held together by wires and rods to show their spatial relationships to each other
articulated skeletons
Vertebra C1 is called the (X) because it supports the head in a manner reminiscent of Atlas, the giant of Greek mythology who was condemned by Zeus to carry the heavens on his shoulders.
atlas
Skeleton is divided into two regions:
axial skeleton and appendicular skeleton
Vertebra C2, the (X), allows rotation of the head as in gesturing "no."
axis
In life, the dura mater stretches over the sella turcica and attaches to the anterior clinoid processes. A stalk penetrates the dura to connect the pituitary gland to the
base of the brain
From the rear of the skull The occipital bone continues anterior to this as a thick median plate, the
basilar part.
Bones exhibit a variety of ridges, spines, bumps, depressions, canals, pores, slits, cavities, and articular surfaces called
bone markings
This is not a single bone but simply the dome of the top of the skull;
calvaria (skullcap) - it is composed of parts of multiple bones that form the roof and walls
The relatively complex shape of the temporal bone is best understood by dividing it into four parts - 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, an opening on its posteromedial surface, allows passage of a nerve that carries signals for hearing and balance from the inner ear to the brain. On the inferior surface of the petrous part are two prominent foramina named for the major blood vessels that pass through them: (a) The carotid canal is a passage for the internal carotid artery, a major blood supply to the brain. This artery is so close to the inner ear that one can sometimes hear the pulsing of its blood when the ear is resting on a pillow or the heart is beating hard. (b) The jugular foramen is a large, irregular opening just medial to the styloid process, between the temporal and occipital bones. Blood from the brain drains through this foramen into the internal jugular vein of the neck. Three cranial nerves also pass through this foramen
Anatomical Features (Markings) of Bones - A tubular passage or tunnel in a bone (auditory canal of the skull)
canal
Beyond the age of 3 years, the vertebral column is slightly S-shaped, with four bends called the
cervical, thoracic, lumbar, and pelvic curvatures
Rib 1 is peculiar. On an articulated skeleton, you must look for its vertebral attachment just below the base of the neck; much of this rib lies above the level of the .
clavicle
The (X) braces the shoulder, keeping the upper limb away from the midline of the body. It also transfers force from the arm to the axial region of the body, as when doing pushups.
clavicle
Anatomical Features (Markings) of Bones - A rounded knob that articulates with another bone (occipital condyles of the skull)
condoyle
In some people, a (X) is found posterior to each occipital condyle. A small vein from a blood sinus of the brain passes through here.
condylar canal
Clavicle - Near the acromial end is a rough tuberosity called the
conoid tubercle—a ligament attachment that faces toward the rear and slightly downward.
The (X) is named for a vague resemblance to a crow's beak, but is shaped more like a bent finger; it provides attachment for tendons of the biceps brachii and other muscles of the arm.
coracoid process
The anterior branch of the ramus is a blade called the (X). It is the point of insertion for the temporalis muscle, which pulls the mandible upward when you bite.
coronoid process
There are 12 pairs of ribs, with no difference in number between the sexes. Each is attached at its posterior (proximal) end to the vertebral column, and most of them are also attached at the anterior (distal) end to the sternum. The anterior attachment is by way of a long strip of hyaline cartilage called the
costal cartilage
Thoracic cage inferior border is the arc of the lower ribs, called the
costal margin.
Bones that enclose the brain;
cranial bones
Cavities in the skull include
cranial cavity, orbits (eye sockets), nasal cavity, oral (buccal) cavity, middle- and inner-ear cavities, and paranasal sinuses
Cranial bones are those that enclose the brain; collectively, they compose the
cranium (braincase).
Anatomical Features (Markings) of Bones - A narrow ridge (iliac crest of the pelvis).
crest
C2 - the axis - most distinctive feature is a prominent knob called the (X), on its anterosuperior side.
dens or odontoid process
Bones taken apart so their surface features can be studied in more detail
disarticulated skeletons
The thickest and toughest of the meninges, called (X), is pressed against the inside of the cranium in most places and firmly attached to it at a few points.
dura mater
Anatomical Features (Markings) of Bones - An expanded region superior to a condyle (medial epicondyle of the femur)
epicondyle
The medial and lateral (X) are the widest points of the femur, easily palpated at the knee.
epicondyles
Other features of the occipital bone can be palpated on the back of your head. One is a prominent medial bump called the (X)—the attachment for the nuchal ligament, which binds the skull to the vertebral column.
external occipital protuberance
Anatomical Features (Markings) of Bones - A smooth, flat, slightly concave or convex articular surface (articular facets of the vertebrae)
facet
These do not enclose the brain but lie anterior to the cranial cavity.
facial bones
Ribs 8 through 12 are called (X) because they lack independent cartilaginous connections to the sternum.
false ribs - In 8 through 10, the costal cartilages sweep upward and end on the costal cartilage of rib 7
The (X) is the longest and strongest bone of the body, measuring about one-quarter of one's height
femur
The (X) is a slender lateral strut that helps to stabilize the ankle.
fibula - It does not bear any of the body's weight; indeed, orthopedic surgeons sometimes remove part of the fibula and use it to replace damaged or missing bone elsewhere in the body.
The medial malleolus is part of the tibia, and the lateral malleolus is the part of the
fibula.
Anatomical Features (Markings) of Bones - A slit through a bone (orbital fissures behind the eye)
fissure
Unlike the other carpal bones, the pisiform is a sesamoid bone; it is not present at birth but develops around the age of 9 to 12 years within the tendon of the (X).
flexor carpi ulnaris muscle
Ribs 11 and 12 have no anterior connection and thus are called
floating ribs
Spaces between the unfused cranial bones are called (X), after the fact that pulsation of the infant's blood can be felt there.
fontanelles
Anatomical Features (Markings) of Bones - A hole through a bone, usually round (foramen magnum of the skull) .
foramen
An irregular gash called the (X) occurs at the junction of the sphenoid, temporal, and occipital bones. It is filled with cartilage in life and transmits no major vessels or nerves.
foramen lacerum
The occipital bone forms the rear of the skull (occiput) and much of its base. Its most conspicuous feature, the (X), admits the spinal cord to the cranial cavity;
foramen magnum
Bones of the skull have especially conspicuous (X) — these holes that allow passage for nerves and blood vessels.
foramina (singular foramen)
The axis is the first vertebra that exhibits a spinous process. In vertebrae C2 through C6, the process is (X), at its tip
forked, or bifid - This fork provides attachment for the nuchal ligament of the back of the neck.
Anatomical Features (Markings) of Bones - A shallow, broad, or elongated basin (mandibular fossa)
fossa
The carpal bones are arranged in two rows of (X) bones each. Although they are colloquially called wrist bones, the narrow point where one might wear a wristwatch is at the distal end of the radius and ulna.
four
Anatomical Features (Markings) of Bones - A small pit (fovea capitis of the femur)
fovea
Femur - A ligament extends from the acetabulum to a pit, the
fovea capitis
The (X) extends from the forehead back to a prominent coronal suture, which crosses the crown of the head from right to left and joins the frontal bone to the parietal bones. The frontal bone forms the anterior wall and about one-third of the roof of the cranial cavity, and it turns inward to form nearly all of the anterior cranial fossa and the roof of the orbit.
frontal bone
The relatively shallow anterior cranial fossa is crescent-shaped and accommodates the
frontal lobes of the brain.
The smooth area of the frontal bone just above the root of the nose is called the
glabella
The dagger-shaped body, or (X), is the longest part of the sternum, lying at the level of vertebrae T5 through T9.
gladiolus
The scapula also articulates with the humerus at the
glenohumeral joint.
The (X) is a shallow socket that articulates with the head of the humerus, forming the glenohumeral joint.
glenoid cavity
The humerus has a hemispherical head that articulates with the
glenoid cavity of the scapula
The median body of the hyoid is flanked on either side by hornlike projections called the
greater and lesser horns (cornua)
Distal to the head is a constricted neck and then two massive, rough processes called the (X), which are insertions for the powerful muscles of the hip.
greater and lesser trochanters
Bones of the toes, like those of the fingers, are called phalanges. The great toe is the (X) and contains only two bones, the proximal and distal phalanx I.
hallux
The hamate can be recognized by a prominent hook called the (X) on the palmar side.
hamulus - The hamulus is an attachment for the flexor retinaculum, a fibrous sheet in the wrist that covers the carpal tunnel
Anatomical Features (Markings) of Bones - The prominent expanded end of a bone, sometimes rounded (head of the femur)
head
Rib 1 - At the vertebral end, it exhibits a knobby (X) that articulates with the body of vertebra T1.
head
Vertebra Co1 has a pair of (X) that serve as attachment points for ligaments that bind the coccyx to the sacrum.
horns (cornua)
The (X) bone is a slender U-shaped bone between the chin and larynx
hyoid
At the anterolateral edge of each occipital condyle is a (X), named for the hypoglossal nerve that passes through it to innervate the muscles of the tongue.
hypoglossal canal
The hip bones have three distinctive features that will serve as landmarks for further description. These are the
iliac crest (superior crest of the hip); acetabulum (the hip socket—named for its resemblance to vinegar cups used on ancient Roman dining tables); and obturator foramen (a large round-to-triangular hole below the acetabulum, closed by a ligament called the obturator membrane in living persons).
The adult hip bone forms by the fusion of three childhood bones called the
ilium, ischium, and pubis
Just behind the incisors (front teeth) is a median pit, the (X), which is a passage for an artery to the palate and a nerve to the lower part of the nasal septum and the six front teeth of the maxilla.
incisive fossa
A rib articulates with the
inferior costal facet of the upper vertebra and the superior costal facet of the vertebra below that.
There are three conchae in the nasal cavity. The superior and middle conchae are parts of the ethmoid bone. The (X) —the largest of the three—is a separate bone
inferior nasal concha
By pulling down on the occipital bone, some of these muscles help to keep the head erect. The deeper (X) provides attachment for some of the deep neck muscles.
inferior nuchal line
The maxilla forms part of the floor of the orbit, where it exhibits a gash called the (X) that angles downward and medially
inferior orbital fissure
Each maxilla extends from the teeth to the inferomedial wall of the orbit. Just below the orbit, it exhibits an (X), which provides passage for a blood vessel to the face and a nerve that receives sensations from the nasal region and cheek.
infraorbital foramen
The radius and ulna are attached along their shafts by a ligament called the (X), which is attached to an angular ridge called the interosseous margin on each bone.
interosseous membrane (IM)
The two hip bones articulate with each other on the anterior side of the pelvis, where they are joined by a pad of fibrocartilage called the
interpubic disc.
The trochanters are connected on the posterior side by a thick oblique ridge of bone, the intertrochanteric crest, and on the anterior side by a more delicate (X).
intertrochanteric line
When two vertebrae are joined, they exhibit an opening between their pedicles called the
intervertebral foramen - This allows passage for spinal nerves that connect with the spinal cord at regular intervals. Each foramen is formed by an inferior vertebral notch in the pedicle of the upper vertebra and a superior vertebral notch in the pedicle of the lower one
The relatively complex shape of the temporal bone is best understood by dividing it into four parts - 2) The tympanic part
is a small ring of bone that borders the opening of the external acoustic meatus, or ear canal. It has a pointed spine on its inferior surface, the styloid process, named for its resemblance to the stylus used by ancient Greeks and Romans to write on wax tablets. The styloid process provides attachment for muscles of the tongue, pharynx, and hyoid bone.
The occipital bone displays impressions left by large venous sinuses that drain blood from the brain. One of these grooves travels along the midsagittal line. Just before reaching the foramen magnum, it branches into right and left grooves that wrap around the occipital bone like outstretched arms before terminating at the
jugular foramina.
The proximal end of a metacarpal bone is called the base, the shaft is called the body, and the distal end is called the head. The heads of the metacarpals form the (X) when you clench your fist.
knuckles
The (X) form part of the medial wall of each orbit. They are the smallest bones of the skull, about the size of the little fingernail.
lacrimal bones
A depression called the (X) houses a membranous lacrimal sac in life. Tears from the eye collect in this sac and drain into the nasal cavity.
lacrimal fossa
Immediately proximal to these condyles, the humerus flares out to form two bony processes, the (X), the widest points felt when you palpate your elbow.
lateral and medial epicondyles - The medial epicondyle protects the ulnar nerve, which passes close to the surface across the back of the elbow. This epicondyle is popularly known as the "funny bone" because striking the elbow on the edge of a table stimulates the ulnar nerve and produces a sharp tingling sensation.
The (X) extends from heel to little toe and includes the calcaneus, cuboid, and metatarsals IV and V.
lateral longitudinal arch
The relatively complex shape of the temporal bone is best understood by dividing it into four parts - 3) The mastoid part
lies posterior to the tympanic part. It bears a heavy mastoid process, which you can palpate as a prominent lump behind the earlobe. It is filled with small air sinuses that communicate with the middle-ear cavity. These sinuses are subject to infection and inflammation (mastoiditis), which can erode the bone and spread to the brain. A groove called the mastoid notch lies medial to the mastoid process. It is the origin of the digastric muscle, which opens the mouth. The notch is perforated at its anterior end by the stylomastoid foramen, which is a passage for the facial nerve, and at its posterior end by the mastoid foramen which passes a small artery and vein from the brain.
Anatomical Features (Markings) of Bones - A slightly raised, elongated ridge (nuchal lines of the skull)
line
The (X) is the strongest bone of the skull and the only one that can move significantly. It supports the lower teeth and provides attachment for muscles of mastication and facial expression.
mandible
The ramus is somewhat Y-shaped. Its posterior branch, called the condylar process, bears the (X)—an oval knob that articulates with the mandibular fossa of the temporal bone.
mandibular condyle
Just below the notch, on the medial surface of the ramus, is the (X). The nerve and blood vessels that supply the lower teeth enter this foramen and then travel through the bone of the mandibular body, giving off branches to each tooth along the way.
mandibular foramen
It is the point of insertion for the temporalis muscle, which pulls the mandible upward when you bite. The U-shaped arch between the two processes is the
mandibular notch.
The (X) is the broad superior portion of the sternum, shaped like the knot of a necktie. It lies at the level of vertebrae T3 to T4.
manubrium
These are the largest facial bones. They form the upper jaw and meet each other at a median intermaxillary suture
maxillae
Anatomical Features (Markings) of Bones - A canal (external acoustic meatus of the ear)
meatus
The (X), which essentially extends from heel to hallux, is formed from the calcaneus, talus, navicular, cuneiforms, and metatarsals I to III. It is normally well above the ground, as evidenced by the shape of a wet footprint.
medial longitudinal arch
The distal group forms a row of four bones. Proceeding from the medial to lateral, these are the
medial, intermediate, and lateral cuneiforms and the cuboid. The cuboid is the largest.
In the sacrum the spinous processes of the vertebrae fuse into a ridge called the
median sacral crest - The transverse processes fuse into a less prominent lateral sacral crest on each side of the median crest
The manubrium has a (X), which you can easily palpate between your clavicles (collarbones), and right and left clavicular notches where it articulates with the clavicles.
median suprasternal (jugular) notch
The point of the chin itself is called the
mental protuberance.
The mandible develops as separate right and left bones in the fetus, joined by a median cartilaginous joint called the (X) at the point of the chin.
mental symphysis
Bones of the palm are called (X).
metacarpals - Metacarpal I is located proximal to the base of the thumb and metacarpal V proximal to the base of the little finger.
The remaining bones of the foot are similar in arrangement and name to those of the hand. The proximal (X) are similar to the metacarpals.
metatarsals
Two small rectangular (X) form the bridge of the nose and support cartilages that shape its lower portion.
nasal bones
On either side of the foramen magnum is a smooth knob called the (X), where the skull rests on the vertebral column.
occipital condyle
Trochlear notch that wraps around the trochlea of the humerus. The posterior side of this notch is formed by a prominent (X) —the bony point where you rest your elbow on a table.
olecranon
Ethmoid bone - The greater wing also forms part of the lateral surface of the cranium just anterior to the temporal bone. 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
The hip bones are also frequently called the
ossa coxae or innominate bones
These divide the oral and nasal cavities from each other posteriorly. Each has an L shape formed by a horizontal plate and a perpendicular plate.
palatine bones - Each is marked by a large greater palatine foramen, a nerve passage to the palate.
Most of the hard palate is formed by horizontal extensions of the maxilla called
palatine processes
The right and left (X) form most of the cranial roof and part of its walls
parietal bones
Externally, the parietal bones have few features. A (X) sometimes occurs near the corner of the lambdoid and sagittal sutures. It is an exit for a small vein from a blood sinus atop the brain.
parietal foramen
The (X) is a roughly triangular sesamoid bone embedded in the tendon of the knee. It is cartilaginous at birth and ossifies at 3 to 6 years of age.
patella, or kneecap,
The (X) supports the arm and links it to the axial skeleton.
pectoral girdle (shoulder girdle)
The pelvis has a bowl-like shape with the broad greater (false) pelvis between the flare of the hips, and the narrower lesser (true) pelvis below. The two are separated by a round margin called the
pelvic brim
The (X) is a bowl-shaped structure composed of these bones as well as the ligaments and muscles that line the pelvic cavity and form its floor.
pelvis
The bones of the fingers are called
phalanges
The sella turcica consists of a deep pit called the hypophyseal fossa, which houses the
pituitary gland, a raised anterior margin called the tuberculum sellae, and a posterior margin called the dorsum sellae.
On the anterior side of the femur, a smooth medial depression called the patellar surface articulates with the patella. On the posterior side is a flat or slightly depressed area called the (X)
popliteal surface.
The internal openings of the nasal cavity seen here are called the
posterior nasal apertures, or choanae.
The thoracic and pelvic curvatures are called (X) because they exist from birth.
primary curvatures - The cervical and lumbar curvatures are called secondary curvatures because they develop later, in the child's first few years of crawling and walking.
Anatomical Features (Markings) of Bones - Any bony prominence (mastoid process of the skull)
process
Anatomical Features (Markings) of Bones - A bony outgrowth or protruding part (mental protuberance of the chin)
protuberance
The talus, calcaneus, and navicular are considered the (X) of tarsal bones.
proximal row
The interpubiv disc and the adjacent region of each pubic bone constitute the (X), which can be palpated as a hard prominence immediately above the genitalia.
pubic symphysis
The (X) is the most anterior portion of the hip bone.
pubis (pubic bone)
The (X) has a distinctive discoidal head at its proximal end
radius
The relatively complex shape of the temporal bone is best understood by dividing it into four parts - 1) The squamous part
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.
The body of vertebra S1 juts anteriorly to form a (X), which supports the body of vertebra L5.
sacral promontory
The (X) is a bony plate that forms the posterior wall of the pelvic girdle.
sacrum - It was named sacrum for its prominence as the largest and most durable bone of the vertebral column. In children, there are five separate sacral vertebrae (S1-S5). They begin to fuse around age 16 and are fully fused by age 26.
The short carpal bones allow movements of the hand from side to side and anterior to posterior. The carpal bones of the proximal row, starting at the lateral (thumb) side, are the
scaphoid, lunate, triquetrum, and pisiform
The (X), named for its resemblance to a spade or shovel, is a triangular plate that posteriorly overlies ribs 2 through 7.
scapula
The body of the sphenoid bone contains a pair of sphenoid sinuses and has a saddle like surface feature named the
sella turcica
The vomer and perpendicular plate support a wall of (X) that forms most of the anterior part of the septum.
septal cartilage
Rib 1 - Beyond the tubercle, the rib flattens and widens into a gently sloping blade like (X)
shaft
Anatomical Features (Markings) of Bones - An air-filled space in a bone (frontal sinus of the forehead)
sinus
Anatomical Features (Markings) of Bones - A sharp, slender, or narrow process (mental spines of the mandible)
spine
Extending from the apex of the arch, a projection called the (X) is directed posteriorly and downward.
spinous process
At the distal end (head) of the ulna is a medial
styloid process.
Anatomical Features (Markings) of Bones - A groove for a tendon, nerve, or blood vessel (intertubercular sulcus of the humerus)
sulcus
A pair of (X) projects upward from one vertebra and meets a similar pair of inferior articular processes that projects downward from the vertebra above
superior articular processes - These processes restrict twisting of the vertebral column, which could otherwise severely damage the spinal cord.
A prominent medial bump called the external occipital protuberance—the attachment for the nuchal ligament, which binds the skull to the vertebral column. A ridge, the (X), can be traced horizontally from this protuberance toward the mastoid process
superior nuchal line - It defines the superior limit of the neck and provides attachment to the skull for several neck and back muscles.
Immediately proximal to the epicondyles, the margins of the humerus are called the lateral and medial (X). These are attachments for certain forearm muscles.
supracondylar ridges
Deep to the eyebrows it has a ridge called the supraorbital margin. Each margin is perforated by a single
supraorbital foramen - which provides passage for a nerve, artery, and veins.
Deep to the eyebrows it has a ridge called the
supraorbital margin
veins. In some people, the edge of this supraorbital foramen breaks through the margin of the orbit and forms a
supraorbital notch.
Although it may seem to consist only of the mandible (lower jaw) and "the rest," it is composed of 22 bones and sometimes more. Most of these are connected by immovable joints called (X), which are visible as seams on the surface
sutures
The second-largest tarsal bone, and the most superior, is the (X). It has three articular surfaces: an inferoposterior one that articulates with the calcaneus, a superior trochlear surface that articulates with the tibia, and an anterior surface that articulates with a short, wide tarsal bone called the navicular.
talus
The (X) bones of the ankle are arranged in proximal and distal groups somewhat like the carpal bones of the wrist
tarsal - groups somewhat like the carpal bones of the wrist. Because of the load-bearing role of the ankle, however, their shapes and arrangement are conspicuously different from those of the carpal bones, and they are fully integrated into the structure of the foot.
If you palpate your skull just above and anterior to the ear—that is, the temporal region—you can feel the (X), which forms the lower wall and part of the floor of the cranial cavity
temporal bone
A pair of slight thickenings, the superior and inferior (X), form an arc across the parietal and frontal bones.
temporal lines - They mark the attachment of the large, fan-shaped temporalis muscle, a chewing muscle that converges on the mandible.
The meeting of this mandibular condyle with the temporal bone forms a hinge, the (X)
temporomandibular joint (TMJ)
There are 12 thoracic vertebrae (T1-T12), corresponding to
the 12 pairs of ribs attached to them
The bones are joined at these points only by fibrous membranes, in which intramembranous ossification is completed later. Four of these sites are especially prominent and regular in location:
the anterior, posterior, sphenoid (anterolateral), and mastoid (posterolateral) fontanelles
The appendicular skeleton includes
the bones of the upper limb and pectoral girdle and the bones of the lower limb and pelvic girdle.
The posterior cranial fossa is deepest and houses a large posterior division of the brain called
the cerebellum.
The pectoral girdle skeleton. It consists of two bones on each side of the body:
the clavicle (collarbone) and scapula (shoulder blade).
Is an anterior cranial bone located between the eyes
the ethmoid bone
The cranium is a rigid structure with an opening, called (X), where the spinal cord meets the brain.
the foramen magnum (literally "large hole")
The sinuses are names for the bones in which they occur
the frontal, sphenoid, ethmoid, and maxillary sinuses.
These are the three auditory ossicles in each middle ear cavity and the hyoid bone beneath the chin. The auditory ossicles —named
the malleus (hammer), incus (anvil), and stapes
The sternum (breastbone) is a bony plate anterior to the heart. It is subdivided into three regions:
the manubrium, body, and xiphoid process.
The internal openings of the nasal cavity seen here are called the posterior nasal apertures, or choanae. Lateral to each aperture, the sphenoid bone exhibits a pair of parallel plates
the medial and lateral pterygoid plates - Each plate has a narrower inferior extension called the pterygoid process. These plates and processes provide attachment for some of the jaw muscles. The sphenoid sinus occurs within the body of the sphenoid bone.
In the cranium the delicate brain tissue does not come directly into contact with the bones, but is separated from them by three membranes called
the meninges
On the anterolateral surface of the body, (X) permits the passage of nerves and blood vessels of the chin.
the mental foramen
The axial skeleton, which forms the central supporting axis of the body, includes
the skull, auditory ossicles, hyoid bone, vertebral column, and thoracic cage (ribs and sternum).
The middle cranial fossa, which drops abruptly deeper, is shaped like a pair of outstretched bird's wings and accommodates
the temporal lobes
Pollex
thumb
The rough anterior surface of the upper tibia, the (X), can be palpated just below the patella..
tibial tuberosity
The (X) includes the cuboid, cuneiforms, and proximal heads of the metatarsals. These arches are held together by short, strong ligaments.
transverse arch
All seven cervical vertebrae have a prominent round (X) in each transverse process.
transverse foramen - These foramina provide 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 from the brain).
Cervical vertebrae C3 through C6 are similar to the typical vertebra described earlier, with the addition of the
transverse foramina and bifid spinous processes.
The dens projects into the vertebral foramen of the atlas, where it is nestled in a facet and held in place by a
transverse ligament
Carpal bones - The bones of the distal row, again starting on the lateral side, are the (X).
trapezium, trapezoid, capitate, and hamate
Anatomical Features (Markings) of Bones - Two massive processes unique to the femur
trochanter
Each has its own costal cartilage connecting it to the sternum; because of this feature, ribs 1 through 7 are called
true ribs
Anatomical Features (Markings) of Bones - A small, rounded process (greater tubercle of the humerus)
tubercle
Rib 1 - Immediately distal to the head, the rib narrows to a neck and then widens again to form a rough area called the (X)
tubercle
Anatomical Features (Markings) of Bones - A rough elevated surface (tibial tuberosity)
tuberosity
Pelvic girdle to consist of a complete ring composed of three bones
two hip bones and the sacrum
At the proximal end of the (X) is a deep, C-shaped trochlear notch that wraps around the trochlea of the humerus.
ulna
Vertebra C7 is a little different—its spinous process is not bifid, but it is especially long and forms a prominent bump on the lower back of the neck. C7 is sometimes called the (X) because of this especially conspicuous spinous process.
vertebra prominens
Posterior to the body of each vertebra is a triangular space called the
vertebral foramen.
The (X) forms the inferior half of the nasal septum. Its name literally means "plowshare," which refers to its resemblance to the blade of a plow.
vomer
Phalanges are identified by roman numerals preceded by proximal, middle, and distal. For example the left proximal phalanx IV is where
where people usually wear wedding rings;
At the inferior end of the sternum (vertebral level T10 to T11) is a small, pointed (X) that provides attachment for some of the abdominal muscles.
xiphoid process
The (X) form the angles of the cheeks at the inferolateral margins of the orbits and part of the lateral wall of each orbit; they extend about halfway to the ear
zygomatic bones
Each zygomatic bone has an inverted T shape and usually a small (X) near the intersection of the stem and crossbar of the T.
zygomaticofacial foramen
The pelvis is the most sexually dimorphic part of the skeleton
—that is, the one whose anatomy most differs between the sexes.
Thoracic vertebrae lack the transverse foramina and bifid processes that distinguish the cervicals, but possess the following distinctive features of their own:
• The spinous processes are relatively pointed and angle sharply downward. • The body is somewhat heart-shaped, more massive than in the cervical vertebrae but less than in the lumbar vertebrae. • The body has small, smooth, slightly concave spots called costal facets for attachment of the ribs. • Vertebrae T1 through T10 have a shallow, cuplike transverse costal facet at the end of each transverse process. These provide a second point of articulation for ribs 1 to 10. There are no transverse costal facets on T11 and T12 because ribs 11 and 12 attach only to the bodies of those two vertebrae.