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
???????