Chapter 9: The Axial Skeleton

crista galli

- "Rooster's comb"; a superior projection that teaches to the dura mater, helping to secure the brain within the skull - part of ethmoid bone

sella turcica

- "Turkish saddle" located on the superior surface of the body; the seat of the saddle, called the "hypophyseal fossa," holds the pituitary gland - part of sphenoid bone

ribs

- 12 pairs - form walls of thoracic cage - all articulate posteriorly w/ vertebral column via their heads and tubercles and then curve downward and towed the anterior body surface

facial bones

- 14 bones - support eyes and position them anteriorly - provide attachment sites for facial muslces

phalanges

- 14 bones of the fingers (digits) - miniature long bones - each finger contains 3 (proximal, middle, distal), except the thumb which has only two (proximal and distal)

Lacrimal (facial) bones

- 2 - 1. forms part of the medial orbit in b/t the maxilla and ethmoid bone - 2. Lacrimal fossa -- houses the lacrimal sac, which helps to drain tears from the nasal cavity

zygomatic bones

- 2 - commonly called the cheekbones; each forms part of the lateral orbit

maxilla

- 2 - form the upper jaw and parts of the hard palate, orbits, and nasal cavity - keystone facial bones b/c they articulate w/ all other facial bones except the mandible

palatine

- 2 - forms the posterior hard palate, a small part of the nasal cavity, and part of the orbit

ischial spine

- located superior to the ischial tuberosity and projects medially into the pelvic cavity - part of ischium

ligaments of the knee joint

- medial collateral - lateral collateral - medial meniscus - lateral meniscus - anterior cruciate - posterior cruciate

false ribs

- middle 5 ribs that attach indirectly to the sternum or entirely lack a sternal attachment - rib pairs 8-10 have indirect cartilage attachments to sternum via the costal cartilage of rib 7

pronation

- movement of the palm of the hand from an anterior or upward-facing position to a posterior or downward-facing position - distal end of the radius rotates over the ulna so that the bones form an X with pronation of the forearm

manubrium

- superior most in sternum --- looks like the knot of a tie - articulates w/ the clavicle (collarbone) laterally

types of fibrous joints

- sutures (short fibers) (ex: squamous suture b/t parietal and temporal bones) - syndesmoses (longer fibers) (b/t tibia and fibula)

Each foot has a total of _____ bones

26

coccyx

3-5 fused bones

T/F? The fingers of the hand and the toes of the foot --- with the exception of the great toe and the thumb --- each have three phalanges

TRUE

mandibular condyle

articulate with the mandibular fossae of the temporal bones

mandibular notch

separate the condylar process and the coronoid process

nasal bone

small rectangular bones forming the bridge of the nose

C3-C7

smallest and lightest vertebrae - spinous process is short and bifurcated

The axial skeleton can be divided into what 3 parts?

the skull, vertebral column, and thoracic cage/bony thorax

vomer

thin, blade-shaped bone that forms the inferior nasal septum

the _______ vertebrae articulate with the corresponding ribs

thoracic

true/vertebrosternal ribs

first 7 ribs that attach directly to sternum by their "own" costal cartilages

trochlea of humerus

flared medial condyle that articulates with the ulna

parietal bone

form the superior and lateral aspects of the skull

pelvic/hip girdle

formed by the two hip bones and the sacrum

frontal bone

forms the forehead, superior part of the orbit, and the floor of the anterior cranial fossa

occipital bone

forms the posterior aspect and most of the base of the skull

symphyses

found in intervertebral joints

7 skull bones that form the orbit

frontal, sphenoid, ethmoid, lacrimal, maxilla, palatine, zygomatic

DETERMINE R/L for:

humerus scapula coxal bone femur tibia

hip bone is a result of the fusion of what 3 bones?

ilium, ischium, pubis

synarthroses

immovable joints

forearm

in anatomical position: radius is in the lateral position and the radius and ulna are parallel

acromion of scapula

lateral end of the spine of the scapula that articulates with the clavicle to form the AC joint

radius

lateral in the anatomical position, parallel to ulna - in forearm

greater tubercle of humerus

lateral lateral prominence; site of the attachment of rotator cuff muscles

the lower jawbone, or (maxilla, mandible) articulates with the temporal bones in the only freely movable joints in the skull

mandible

2 single bones of the facial bones

mandible and vomer (rest of the 12 are paired)

ulna

medial in anatomical position, parallel to radius - in forearm

abduction

movement of a limb away from the midline of the body, along the frontal plane, or the fanning movement of fingers or toes when they are spread apart

adduction

movement of a limb toward the midline of the body or drawing the fingers or toes together; the opposite of abduction

vertebral (spinal) foramen

opening enclosed by the body and vertebral arch; a passageway for the spinal cord CERVICAL - triangular THORACIC - circular LUMBAR - triangular

mental foramen

paired openings on the body (lateral to the midline); transmit blood vessels and nerves to the lower lip and skin of the chin

The ____________, or "knee cap," is a sesamoid bone that is found within the quadriceps tendon.

patella

The (pectoral/pelvic) girdle attaches the upper limb to the axial skeleton

pectoral

coracoid process of scapula

projects above glenoid cavity as a hooklike process; helps attach the biceps brachii muscle

olecranon process of ulna

prominent process on the posterior proximal ulna; articulates with the olecranon fossa of the humerus when the forearm is extended

2 bones of the forearm

radius and ulna

transverse processes

two lateral projections from the vertebral arch CERVICAL - contain formina THORACIC - bear facets for ribs (except T11 and T12) LUMBAR - thin and tapered

squamous suture

where each parietal bone meets the temporal bone, on each lateral aspect of the skull

lambdoidal suture

where parietal bones meet occipital bone posteriorly

inferior nasal concha

- 2 - inferior turbinate; each forms part of the lateral walls of the nasal cavities; improves the airflow through the nasal cavity

vertebrae of vertebral column

- 24 single bones: 7 cervical 12 thoracic 5 lumbar

axial skeleton

- 3 parts: skull, vertebral column, thoracic cage - forms longitudinal axis of the body and protects the brain, spinal cord, heart and lungs

bones of foot

- 7 tarsal bones - 5 metatarsals (form instep) - 14 phalanges (form toes)

cranium

- 8 bones (1 frontal, 2 parietal, 2 temporal, 1 occipital, 1 sphenoid, 1 ethmoid) - enclose and protect fragile brain tissue

carpals

- 8 bones of the wrist - 2 irregular rows of four bones each

zygomatic process

- a bridgelike project that articles with the zygomatic bone to form the zygomatic arch - part of temporal bone - "process" - it attaches

axis (c2)

- acts as a pivot for the rotation of the atlas (and skull) above

cartilaginous joints

- adjoining bones united by cartilage - no joint cavity

synovial joints

- articulating bone ends separated by a joint w/ synovial fluid - all are diathrotic - variation in mobility - most joints in body are synovial

saddle synovial joints

- articulating surfaces are saddle shaped; one surface is concave, the other surface is convex - biaxial: flexion, extension, adduction, abduction - ex: carpometacarpal joint of the thumb

herniated disc

- as person ages, water content of discs decreases and discs become thinner and less compressible; weakening of ligaments and tendons of vertebral column

ball-and-socket joints

- ball-shaped head of one bone fits into the cupcake depression of the other bone - multiaxial: flexion, extension, adduction, abduction, rotation - ex: shoulder, hip joints

tarsal bones

- body weight is concentrated on the two largest tarsals, which form the posterior aspect of foot --> calcaneus (heel bone) & talus (tibia and calcaneus)

Fibrous joints

- bones joined by fibrous tissues (dense regular connective tissue) - no joint cavity - most are synarthrotic

sternum

- breastbone - typical flat bone - result of the fusion of three bones = manibrium, body, and xiphoid process - attached to the first 7 pairs of ribs

external acoustic meatus

- canal leading to the middle ear and eardrum - part of temporal bone

circumduction

- combination of flexion, extension, abduction, adduction commonly observed in ball-and-socket joints like shoulder - limb as a whole outlines a cone

sacrum

- composite bone formed from fusion of 5 vertebrae - superiorly --> articulates w/ L5; inferiorly --> connects w/ coccyx

xiphoid process

- constructs the inferior end of the sternum and lies at the level of the fifth intercostal space - made of hyaline cartilage in children; usually ossified in adults over the age of 40

pelvis

- deep structure formed by the HIP BONES, SACRUM, COCCYX - bones are heavy and massive - attach securely to axial skeleton

female pelvis

- differences for childbearing - wider, shallower, lighter, rounder - tilted forward - true pelvis defines birth canal - acetabula is smaller and farther apart - pubic arch has broader angle (80-90 degrees); more rounded - sacrum is wider, shorter, less curved

medial and lateral condyles of femur

- distal "wheel shaped" projections that articulate w/ the tibia, each condole has a corresponding epicondyle

pectoral/shoulder girdles

- each consist of 2 bones: anterior clavicle and posterior scapula - attach upper limbs to axial skeleton and provide attachment points for many trunk and neck muscles - exceptionally light and allows the upper limb a degree of mobility not seen anywhere else in the body

body/centrum of vertebra

rounded central portion of the vertebra, which faces anteriorly in the human vertebral column CERVICAL - small, wide side to side THORACIC - larger than cervical; heart shaped; bears costal facets LUMBAR - massive, kidney shaped

coronal suture

running in the frontal plane, occurs anteriorly where the parietal bones meet the frontal bone

The __________, on the posterior thorax, are roughly triangular in shape. They have no direct attachment to the axial skeleton but are held in place by trunk muscles.

scapulae

glenoid cavity of scapula

shallow socket that articulates with the head of the humerus

spinous process

single medial and posterior projection from the vertebral arch CERVICAL - short; bifid; projects directly posteriorly THORACIC - long; sharp; projects inferiorly LUMBAR - short; blunt; projects directly posteriorly

amphiarthroses

slightly movable joints

lesser tubercle of humerus

small medial prominence; site of attachment of rotator cuff muscles

radial notch of ulna

small proximal lateral notch that articulates with the head of the radius; forms part of the proximal radioulnar joint

the ______, commonly referred to as the breastbone, is a flat bone formed by the fusion of 3 bones: the manubrium, the body, and the xiphoid process

sternum

bony thorax (3 parts)

sternum, ribs, thoracic vertebrae

primary curvatures

thoracic and sacral - b/c they are present and well developed at birth

what 2 bones form the skeleton of the leg

tibia and fibula

Sagittal suture

where left and right parietal bones meet superiorly in the midline of the cranium

vertebral column

- extending from the skull to pelvis - forms body's major axial support - surrounds and protects delicate spinal cord while allowing spinal nerves to emerge from cord via openings b/t adjacent vertebrae - 24 vertebrae, two composite/fused bones (sacrum and coccyx)

plane synovial joints

- flat or slightly curved bones - non axial: gliding - ex: inter tarsal, intercarpal joints

movements allowed by cervical vertebrae

- flexion and extension - lateral flexion - rotation - the spine region w/ greatest range of movement

movement allowed by lumbar vertebrae

- flexion and extension - some lateral flexion - rotation prevented

plantar flexion

- foot - movement of the ankle joint in which the foot is flexed downward as if standing on one's toes or pointing the toes

dorsiflexion

- foot - movement of the ankle joint that lifts the foot so that its superior surface approaches the shin

eversion

- foot - movement that turns the sole of the foot laterally; the opposite of inversion

inversion

- foot - movement that turns the sole of the foot medially

lateral malleolus of the fibula

- forms the lateral bulge of the ankle and articulates w/ talus - more triangle shaped

fontanelle

- found only in the fetal skull - fibrous membrane - allows for compression of the skull during birth

4 sinus bones

- frontal sinus - maxillary sinus - sphenoid sinus - ethmoidal sinus

obturator foramen

- hole in the pelvis bone - blood vessels and nerves pass

ligaments of the hip joint

- ilio-femoral - pub-femoral - ischiofemoral

dens

- in axis (c2) - aka odontoid process - large vertical process that serves as the pivot point - the articulation b/t C1 and C2 allows you to rotate your head from side to side to indicate "no"

sutures

- interlocking fibrous joints that joins all but one of the bones of the skull (mandible - attached to rest of the skull by a freely movable joint)

ligaments of the elbow joint

- internal or ulnar lateral ligament - radial lateral ligament - anular or orbicular ligament

patella

- kneecap - triangular sesamoid bone enclosed in the quadriceps tendon that secures the anterior thigh muscles to the tibia

atlas (c1)

- lacks a body - its lateral processes contain large concave depressions on their superior surfaces that receive the occipital condyles of the skull - this joint enables us to nod "yes"

greater trochanter of femur

- large lateral projection; serves as a site for muscle attachment on the proximal femur

foramen magnum

- large opening in the base of the bone, which allows the spinal cord to join with the brain stem - part of occipital bone - hole under skull

lesser trochanter of femur

- large posteromedial projection; serves as a site for muscle attachment on the proximal femur

floating ribs

- last 2 ribs (11-12) - have no sternal attachment

phalange bones

- like the fingers of the hand, each toe has 3 phalanges except the great toe, which has two - distal, medial, proximal

mastoid process

- located posterior to the external acoustic meatus; serves as an attachment point for neck muscles - part of temporal bone

rotation

- movement of a bone around its longitudinal axis without lateral or medial displacement - common movement of ball-and-socket joints - describes the movement of the atlas around the dens of the axis

supination

- movement of the palm from a posterior position to an anterior position (the anatomical position); opposite of pronation - during supination, radius and ulna are parallel

extension

- movement that increases the angle of a joint and the distance b/t 2 bones or parts of the body; the opposite of flexion - if extension proceeds beyond anatomical position (bends the trunk backward), it is termed hyperextension

flexion

- movement, generally in the sagittal plane, that decreases the angle of the joint and reduces the distance b/t the two bones - typical of hinge joints (bending the knee/elbow) but is also common at ball-and-socket joints (bending forward at the hip)

styloid process

- needlelike projection that serves as an attachment point for ligaments and muscles of the neck - part of temporal bone

metatarsal bones

- numbered I through V, medial to lateral

metacarpals

- numbered I to V from thumb side of hand toward little finger, radiate out from the wrist like spokes to form palm of the hand

condyloid synovial joints

- oval condyle fits into an oval depression on the other bone - biaxial: flexion, extension, adduction, abduction - ex: metacarpophalangeal (knuckle), radiocarpal joints

intervertebral discs

- pads of fibrocartilage that separate the vertebrae - cushion vertebrae and absorb shocks

movements allowed by thoracic vertebrae

- rotation - lateral flexion possible but limited by ribs - flexion and extension prevented

ischial tuberosity

- rough projection that receives the weight of our body when we are sitting - part of ischium

pivot synovial joints

- rounded bone fits into a sleeve (a concave bone plus a ligament) - uniaxial; rotation - proximal radioulnar, atlantoaxial joints; atlas and axis joint

hinge synovial joints

- rounded or cylindrical bone fits into a concave surface on the other bone - uniaxial: flexion and extension - ex: elbow, interphalangeal joints

occipital condyles

- rounded projections lateral to the foramen magnums that articulate with the first cervical vertebra (atlas) - part of occipital bone

tibia

- shin bone, medial bone of the leg - larger, medial, weight-bearing bone of the leg

humerus

- single bone of the arm - rounded head (fits into glenoid cavity of the scapula) - head is separated from shaft by the anatomical neck and surgical neck

lateral condyle of tibia

- slightly concave surface that articulates w/ lateral condyle of the femur; the inferior region of this condyle articulates w/ the fibula to form the superior tibiofibular joint

medial condyle of tibia

- slightly concave surface that articulates w/ the medial condyle of the femur

acetabulum

- socket where the ilium, ischium, and pubis fuse - receives head of the thigh bone

how to structurally classify articulations

A. fibrous B. cartilaginous C. synovial

how to functionally classify articulations

A. synarthroses (axial) B. amphiarthroses (axial) C. diarthroses

spine of scapula

a ridge of bone on the posterior surface that is easily felt through the skin

The strongest, heaviest bone of the body is in the thigh. It is the: a. femur b. fibula c. tibia

a. femur

articulation b/t C1 and C2

allows head to rotate from side to side indicating NO response

The __________ skeleton is made up of 126 bones of the limbs and girdles

appendicular

clavicle

articulates w/ axial skeleton via the sternum - your "collarbone"

The arm consists of one long bone, the: a. femur b. humerus c. tibia d. ulna

b. humerus

the (body/spinous process) of a typical vertebra forms the rounded, central portion that faces anteriorly in the human vertebral column

body

anatomical position

body is erect, feet slightly apart, head and feet facing forward and palms facing forward

syndesmoses

bones do not interlock - found at distal end of tibia and fibula

orbit

bony cavity that surrounds the eye

3 groups of bones in hand

carpus, metacarpals, phalanges

the skeleton is constructed of:

cartilage and bone

the 7 bones of the neck are called _________ vertebrae

cervical

secondary curvatures

cervical (prominent when baby begins to hold its head up independently) and lumbar (when baby begins to walk)

appendicular skeleton

composed of 126 bones of the appendages and the pectoral and pelvic girdles, which attach the limbs to the axial skeleton

ethmoid bone

contributes to the anterior cranial fossa; forms part of the nasal septum and the nasal cavity; contributes to the medial wall of the orbit

8 bones make up the ___________, which encloses and protects the brain

cranium

2 types of bone in skull

cranium and facial bones

styloid process of ulna

distal pointed projection; located medial to the head of the ulna

styloid process of radius

distal prominence; site of attachment for ligaments that travel to the wrist

scapula

does not articulate with the axial skeleton - your "shoulder blade"

lacrimal bone

each forms part of the medial orbit in between the maxilla and ethmoid bone

T/F? the first seven pairs of ribs are called floating ribs because they have only indirect cartilage attachments to the sternum

false

You are studying a pelvis that is wide and shallow. The acetabula are small and far apart. The pubic arch is rounded and greater than 90 degrees. It appears to be tilted forward, with a wide, short sacrum. Is this a male or female pelvis?

female

acromial (lateral) end of clavicle

flattened lateral end that articulates with the acromion of the scapula to form the acromioclavicular (AC) joint

temporal bone

form the inferolateral aspects of the skull and contribute to the middle cranial fossa; each has squamous, tympanic, and petrous parts

body (of sternum)

forms the bulk of the sternum

medial malleolus of tibia

forms the medial bulge of the ankle

synchondroses

found in epiphyseal plates

diarthroses

freely movable joints

coxal bone

hip bone

mandible

jaw bone - articulates w/ temporal bone to form the only freely movable joints in the skull

articulations

joints

olecranon fossa of humerus

large distal posterior depression that accommodates the olecranon of the ulna

fibula

lateral bone of the leg

The hand consists of three groups of bones. The carpals make up the wrist. The ______________ make up the palm, and the phalanges make up the fingers.

metacarpals

sternal (medial) end of clavicle

oval or triangular medial end that articulates w/ the sternum to form the lateral walls of the jugular notch

head of radius

proximal end of the radius that forms part of the proximal radioulnar joint and articulates with the capitulum of the humerus

tibial tuberosity

roughened anterior surface; site of patellar ligament attachment

types/function classification of cartilaginous joints

- synchondrosis (hyaline cartilage) (ex: b/t costal cartilage of rib 1 and sternum and epiphyseal plate in growing long bones) *synarthrotic - symphysis (fibrocartilage) (ex: intervertebral discs b/t adjacent vertebrae and anterior connection b/t pubic bones) *amphiarthrotic

ligaments of the shoulder joint

- tendon of the biceps muscle - coracoacromial ligament - coracoclavicular ligament = external clavicular ligaments - traverse ligament of the scapula - acromioclavicular ligament - articular capsule - supplemental ligaments of the articular capsule

thoracic vertebrae

- there are 12 (T1-T12) - have a larger body than cervical vertebrae - body is somewhat heart-shaped, w/ two small articulating surfaces (costal facets) on each side - vertebral foramen is oval/round - spinous process is long, w/ sharp downward hook (points downward) - only vertebrae that articulate w/ the ribs

lumbar vertebrae

- there are 5 (L1-L5) - massive clocklike bodies - short, thick, hatchet-shaped spinous processes - spinous process points straight out - kidney-shaped body

cervical vertebrae

- there are 7 (C1-C7) - form the neck portion of the vertebral column - first 2 are highly modified to perform special functions - third through seventh are distinguished from other vertebrae by: --- are smallest, lightest vertebrae --- vertebral foramen is triangular --- spinous process is short and often bifurcated (divided into 2 branches) --- transverse processes are wide

iliac crest

- thick superior margin of bone - part of ilium

femur

- thigh bone - only bone of thigh - heaviest, strongest body of the body - ball-like head of the femur articles with the hip bone via the deep, secure socket of the acetabulum - angles medially as it runs downward to the leg bones --- brings knees in line w/ body's center of gravity - involved in hip and knee joints

male pelvis

- tilted less forward; adapted for support of male's heavier build and stronger muscles; cavity of true pelvis is narrow and deep - bones heavier and thicker; and markings are more prominent - acetabula larger and closer together - pubic arch angle is more acute (50-60 degrees - sacrum - narrow; longer; sacral promontory projects anteriorly

what do the shapes of the articular surfaces determine

- types of movements that can occur at the joint - the structural classification of the joints

5 characteristics of the skeleton

1. SUPPORTS and PROTECTS 2. provides system of LEVERS 3. made up of bones connected at JOINTS/ARTICULATIONS 4. 206 BONES in the adult skeleton 5. composed of: a - COMPACT BONE, b - SPONGY BONE

2 subdivisions of skeleton

1. axial 2. appendicular

movements of synovial joints

1. flexion and extension 2. abduction and adduction 3. rotation and circumduction 4. pronation and supination 5. dorsiflexion and plantar flexion 6. inversion and eversion

characteristics of synovial joints

1. joint surface (space b/t articulating bones - cavity filled w/ synovial fluid) 2. inner layer of joint (synovial membrane composed of loose connective tissue) w/ fibrous layer on outside 3. articular cartilage (hyaline cartilage that covers surfaces of the bones forming the joint) 4. articular capsule (2 layers that enclose joint cavity --- fibrous layer & synovial membrane) 5. fibrocartilage pads

three important landmarks of the sternum

1. jugular notch 2. sternal angle 3. xiphisternal joint

further classification of the skeleton based on gross anatomy

1. long-femur and phalanges 2. short-tarsals and carpals 3. flat-parietal 4. irregular-vertebrae sesamoid and workman

types of synovial joints

1. plane = gliding 2. hinge 3. pivot 4. condyloid or ellipsoidal 5. saddle 6. ball and socket

2 ways of classifying articulations

1. structurally 2. functionally

how many bones of the skull are considered facial bones?

14

cranium

2 major areas for study: cranial value/calvaria (superior, lateral, posterior walls of skull) & cranial base (skull bottom) cranial base has 3 distinct depressions (anterior, middle, posterior cranial fossae

carpus

= wrist

occipitomastoid suture

???????