Skeletal System - Axial (235 #7) Flashcards Preview

Physiology & Anatomy > Skeletal System - Axial (235 #7) > Flashcards

Flashcards in Skeletal System - Axial (235 #7) Deck (57):

axial skeleton

the bones that lie around the longitudinal axis of the human body:
cranium = 8
face = 14
auditory ossicles = 6
hyoid bone = 1
ribs = 24
sternum = 1
vertebrae = 26
TOTAL = 80!


LONG bones

1) greater length than width
2) contain shaft, variable number of extremities or epiphyses
3) slightly curved for strength
4) mostly compact bone tissue in diaphysis and spongy in epiphyses
5) femure, tib/fib, humerus, ulna, radius, phalanges


SHORT bones

1) somewhat cube-shaped, nearly equal in length and width
2) consist of spongy bone except at the surface
3) most carpals & tarsals


FLAT bones

1) generally thin, composed of two nearly parallel plates of compact with layer of spongy between.
2) protection, area for muscle attachment
3) cranial bones, sternum & ribs, scapulae



1) complex shapes that cannot be grouped
2) vertebrae, hip bones, some facial bones, calcaneus



1) develop in tendons with considerable friction, stress and tension.
2) may vary in #, not always completely ossified
3) protect tendons from excessive wear and tear, often change direction of pull of a tendon to increase mech advantage
4) patellae, palms, soles.



small bones located in sutures between some cranial bones - number varies.


Red Bone Marrow Locations

1) flat - ribs, sternum, skull
2) irregular - vertebrae, hips
3) long - proximal femur & humerus
4) short - few


Surface Markings - Depressions/Openings

Sites allowing the passage of soft tissues (nerves, blood vessels, ligaments, tendons) or formation of joints
1) Fissure
2) Foramen
3) Fossa
4) Sulcus
5) Meatus


Surface Markings - Processes

Projections or outgrowths on bone that form joints or attachment points for connective tissue (ligaments, tendons).
1) condyle
2) facet
3) head
1) Crest
2) Epicondyle
3) Line
4) Spinous Process
5) Trochanter
6) Tubercule
7) Tuberosity



narrow slit between adnacent parts of bones through which blood vessels or nerves pass


Foramen (Foramina)

Opening through which blood vessels nerves or ligaments pass



shallow depression



furrow along bone surface that accomodates blood vessel, nerve or tendon



Tubelike opening (e.g. external auditory meatus of temporal bone)



Large round protuberance with a smooth articular surface at end of bone



Smooth, flat, slighly concave or convex articular surface (on vertebrae)



Usually rounded articular projection supported on neck of bone



Prominent ridge or elongated projection



Epi = above. Typically roughened projection above condyle



Long, narrow ridge or border (less prominent than crest)


Spinous Process

Sharp, slender projection



very large projection



variably sized rounded projection



variably-sized projection that has a rough, bumpy surface (ischial tuberosity)



CRANIAL = 8 in total:
Frontal = 1
Parietal = 2
Temporal = 2
Occipital = 1
Sphenoid = 1
Ethmoid = 1

FACIAL = 14 in total:
Palatine = 2
Maxilla = 2
Mandible = 1
Lacrimal = 2
Nasal = 2
Vomer = 1
Inferior Nasal Conchae = 2
Zygomatic = 2


Frontal Bone

1) forms the forehead, the roofs of the orbits (eye sockets) and most of the anterior of the cranial floor.
2) United across middle by metopic suture
3) frontal squama forms forehead, frontal sinuses lie deep to it
4) coronal suture between frontal + parietals
5) supraorbital margins (eyebrows), with supraorbital foramen just medial to them, containing supraorbital nerve & artery.


Parietal Bones

1) form the freater portion of the sides and roof of the cranial cavity.
2) surfaces accommodate blood vessels supplying the dura mater
3) connect via the sagittal suture in the middle
4) lambdoid suture between parietals + occipital
5) parietal foramina near crown


Temporal Bones

1) form the inferior lateral aspects of the cranium and part of the cranial floor
2) temporal squama forms the temple
3) zygomatic process + temporal process of zygomatic bone = zygomatic arch (cheekbone)
4) mandibular fossa + articular tubercule + mandible = temporomandibular joint (TMJ)
5) external auditory meatus = ear canal, internal = facial (VII) and vestibulocochlear (VIII) nerves pass
6) mastoid portion = contains air cells that communicate with middle ear, separated from brain by thin bony partitions. Mastoiditis = inflammation due to middle ear infection
7) styloid & mastoid processes = attachments for neck and tongue (styloid)
8) stylomastoid foramen = facial (VII) nerve
9) petrous portion = houses internal and middle ear, carotid foramen (carotid artery and sympathetic eye nerve) and jugular foramen (jug vein, cranial IX (glossopharyngeal) and X (vagus), XI (accessory).
10) squamous suture = parietal + temporal


Occipital Bone

1) forms the posterior part and most of the base of the cranium
2) contains foramen magnum, where medulla oblongata cxs with spinal cord, and vertebral/spinal arteries pass with the accessory (XI) nerve.
3) occipital condyles articulate with atlas = atlanto-occipital joint (nod yes)
4) hypoglossal canal superior to each condyle - cranial nerve XII (hypoglossal) and asc. pharyngeal artery.
5) external occipital protuberance = bump just above neck, ligamentum nuchae extends to C7 to support head
6) superior and inferior nuchal lines below EOP are points of muscle attachment


Sphenoid Bone

1) middle of the base of the skull = keystone of cranial floor because it articulates with all cranial bones.
2) forms part of the floor, side walls and rear wall of the orbits.
3) butterfly with outstretched wings
4) body is cube-shaped medial portion between ethmoid and occipital, contains sphenoidal sinus (drains into nasal cavity)
5) sella turcica = bony saddle, where hypophyseal fossa contains pituitary gland.
6) anterior to ST is optic foramen (optic nerve II and ophthalmic artery) and superior orbital fissure = blood vessels and cranial nerves.
7) pterygoid processes = posterior region of nasal cavity and attach muscles of mandible. Foramen ovale (mandibular branch of cranial (V) trigemnal), foramen lacerum (asc. pharyngeal artery) and foramen rotundum (maxillary branch of cranial V trigemnal).


Ethmoid Bone

1) delicate, anterior part of cranial floor, medial wall of orbits, superior portion of nasal septum, superior sidewalls of nasal cavity.
2) major superior supporting structure of the nasal cavity and forms extensive surface area in nasal cavity.
3) cribriform plate - roof of cavity, contains olfactory foramina.
4) crista galli - triangular process, point of attachment for falx cerebri, membrane that separates sides of brain.
5) perpendicular plate = superior portion of nasal septum.
6) lateral masses = wall between nasal and orbits. Contain ethmoidal cells = 3-18 air spaces, form ethmoidal sinuses and conchae
7) superior and middle nasal conchae - greatly increase vascular and mucous membrane surface area, warm air, cause inhaled air to swirl to trap particles. Superior are close to olfactory foramina and cribriform plate, where olfactory sensors terminate.


Nasal Bones

small, flattened rectangular-shaped bones that form the bridge of the nose. Provide attachment for a few facial expression muscles.


Lacrimal Bones

thin, fingernail-sized and shaped. Form a part of the medial wall of each orbit, contain a lacrimal fossa that houses the lacrimal sac - structure that cathers tearsa and passes them to the nasal cavity.


Palatine Bones

L-shaped, form the posterior of the hard palate, part of the floor & wall of nasal cavity and some of the orbit floor.


Inferior Nasal Conchae

inferior to the middle nasal conchae are scroll-like. Not involved in sense of smell.



triangular bone on floor of nasal cavity that articulates with the perpendicular plate of the ethmoid bone. Forms inferior part of the bony nasal septum (divides cavity into left & right sides).



1) unite to form the upper jaw bone, articulate with every facial bone except mandible.
2) Most of the orbit floor, lateral walls & floor of nasal cavity and most of the hard palate. 3) Contains large maxillary sinus that empties into nasal cavity.
4) alveolar process contains alveoli (sockets) for upper maxillary teeth.
5) palatine process forms hard palate - if they do not unite during development, cleft palate results.
6) infraorbital foramen = infraorbital blood vessels and nerve (branch of trigeminal V nerve)
7) incisive foramen - just posterior to the incisors = branches of palatine blood vessels and nasopalatine nerve.


Zygomatic Bones

1) prominences of the cheek and part of wall & floor of orbits.
2) temporal + zygomatic = zygomatic arch



1) largest, strongest facial bone
2) only movable skull bone (except ossicles)
3) body (curved, horizontal part) and rami (branches)
4) condylar process on each rami + mandibular fossa and articular tubercle on the temporal bones = TMJ
5) coronoid process attaches temporalis muscle.
6) alveolar process contains sockets for lower mandibular teeth
7) mental foramen = mental nerve (just below second premolar, for freezing @ dentist)
8) mandibular foramen = beginning of mandibular canal, inferior alveolar nerves & blood vessels.


Paranasal Sinuses

Sphenoid, maxillary, frontal & ethmoid. Allow skull to increase in size without a change in mass, increase surface area of nasal mucosa, serve as resonating echo chambers to intensify and prolong sound.



at birth, bone ossification is incomplete - mesenchyme develops into dense connective tissue:
1) anterior fontanel - diamond shaped between parietals and frontal
2) posterior fontanel - midline btwn parietals and occipital bones
3) anterolateral fontanels - small, irregular in shape, frontal + parietal + temporal + sphenoid
4) posterolateral fontanels = laterally, parietal + occipital + temporal


Hyoid Bone

U-shaped, does not articulate with any other bone. Suspended from styloid processes by ligaments & muscles. supports the tongue, attaches tongue muscles and neck & pharynx muscles. Lesser & greater horns. Often fractured during strangulation.


Vertebral Column

24-28" in adult = 33 in total during early dev, then 26 in adult:
cervical = 7
thoracic = 12
lumbar = 5
sacral = 5 (fuse to 1)
coccyx = 4 (fuse to 1)


Normal Curves

increase strength, hold balance in upright position, protect vertebrae from fracture:

cervical + lumbar = bulge out, convex, secondary, form several months after birth

thoracic + sacral = cupping in, concave, primary curves because they maintain fetal curvature


Intervertebral Discs

25% of the height of the vertebrae, from C2 to sacrum.

Annulus Fibrosis = outer, fibrocartilaginous ring
Nucleus Pulposus = inner soft, super elastic

Vertebral height loss: taller in morning, shorter at night (dehydration, compression), With age, height loss is due to bone loss in vertebrae, not discs.


Vertebral Body

1) thick, disc-shaped anterior portion bears weight
2) surfaces are roughened for disc attachment
3) anterior & lateral surfaces contain foramina for blood vessels supplying bone


Vertebral Arch

pedicles = two short, thick processes unite with flat laminae to form arch. The body and arch together form vertebral FORAMEN for the spinal cord - collectively form vertebral canal. When vertebral notches of pedicles are stacked, they form an intervertebral foramen on each side of the column for a single spinal nerve to pass through.



Muscle attachment:
1) transverse x2 - where lamina and pedicle join
2) spinous x1 - posteriorly from the junction of laminae.
Form intervertebral joints:
3) superior articular x2 - with hyaline facets
4) inferior articular x2 - with hyaline facets


Cervical Vertebrae

1) vertebral foramina are largest because they house the enlargement of the spinal cord.
2) C2-C6 have bifid (branching) spinous processes.
3) ATLAS - C1 - ring of bone with anterior & posterior arches and large lateral masses. Lacks body and spinous process. Articulates with occipital condyles to form atlanto-occipital joint (nod yes).
4) AXIS - C2 - dens/odontoid process goes up through the atlas and permits shaking 'no', called atlanto-axial joint.
5) C7 contains vertebra prominens, bump on base of neck.
6) small transverse processes (x2) contain transverse foramina for vertebral artery and associated veins and nerve.
7) discs are thick relative to vertebral bodies


Thoracic Vertebrae

1) longer and stronger than cervical
2) T1-T10 spinous processes are long, laterally flattened and directed inferiorly
3) T11-T12 are shorter, broader, directed more posteriorly.
4) long transverse processes with costal facets for tubercles of ribs
5) bodies have costal facets for heads of ribs (T2-T8 have sup & inf, T10-T12 have 1)
6) discs are thin relative to size of bodies

Movements of the thoracic region are limied by the attachment of ribs to sternum


Lumbar Vertebrae

1) largest and strongest of the unfused bones
2) projections are short and thick
3) spinous processes are quadrilateral and project nearly straight back (large back muscles)
4) discs are THICKEST here



1) triangular bone formed by 5 sacral vertebrae.
2) female is shorter, wider and more curved between S2 and S3.
3) four transverse lines (ridges) and pairs of anterior sacral foramina
4) top side is smooth surface = sacral ala (fused transverse processes of S1)
5) median sacral crest is fused spinous processes and lateral sacral crests are fused transverse processes.
6) sacral canal is continuation of vertebral cavity. sacral hiatus is where S4-S5 lamina don't fuse, with the sacral cornu on each side - connected by ligaments to coccyx.
7) bottom = APEX, top = BASE - ant projection of base is PROMONTORY (used for measurements).
8) auricular surface (sacral tuberosity) + hip bone = sacroilliac joint



triangular fusion of 4 vertebra (20-30yrs). Dorsal surface contains coccygeal cornua connect to sacral cornua with ligaments. Points inferiorly in females, anteriorly in males.



6" in length:
1) manubrium - superior, forms sternal angle with body. Contains one suprasternal notch on top and two clavicular notches to form sternoclavicular joints. Articulates with costal cartilages of R1 & R2.
2) body = middle, largest part, articulates directly or indirectly with costal cartilages of R2-R10.
3) xiphoid process - hyaline during infancy, ossify by 40. CPR landmark, abdominal muscle attachment



1) give structural support to sides of thoracic cavity (1-12)
2) increase in length R1-R7, then decrease R8-R12.
3) costal cartilage is hyaline, attaches to sternum
4) TRUE are vertebrosternal ribs, with sternocostal joints (R1-R7)
5) FALSE - R8-R10 attach together and then to sternum - vertebrochondral ribs. R11 & R12 are floating - vertebral ribs.

costal cartilage inflammation = costochondritis - mimics chest pain associated with heart attack.

HEAD contains facets, neck is just lateral to head, TUBERCLE is where neck joins body (attaches to transverse process of T vert).

Rib fracture =Costal angle is usual point of breakage.
Dislocation = displacement of costal cartilage
Separation = displacement of rib and cartilage


Vertebral Abnormalities

1) herniated (slipped) disc – pressure in nucleus pulpous is enough to rupture it, may protrude posteriorly or into one of the adjacent vertebral bodies.
2) Scoliosis – lateral bending of the vertebral column, usually thoracic.
3) Kyphosis – humpback, increase in thoracic curve, sometimes due to rickets, poor posture, osteoporosis, TB of the spine, degeneration of discs
4) Lordosis – increase in lumbar curve, due to pregnancy, obesity, poor posture, rickets, osteoporosis or TB of the spine
5) Spina Bifida – congenital defect, laminae of L5 and/or S1 fail to develop normally and unite at the midline.
6) Fractures – C1, C2, C4-T7 and T12-L2