The Skeletal System
Part 2
The Appendicular Skeleton
Honors Anatomy & Physiology
The Appendicular Skeleton
2 pectoral girdles
 attach bones of upper limbs to axial
skeleton
 each: 1 clavicle

1 scapula

The Pectoral Girdle
(Shoulder)
S-shaped, (medial ½ convex anteriorly,
lateral ½ concave anteriorly) slender
bone
 lies horizontally across anterior thorax
superior to 1st rib

Clavicle

medial end = sternal end is rounded &
articulates with the manubrium @
sternoclavicular joint
Clavicle
lateral end = acromial end is flat
 articulates with acromion of the scapula
to form acromialclavicular joint

Clavicle
last bone to stop growing
 1 of most frequently fx’d bones (2
curves) usually from fall on outstretched
arm
 or see compression fx in auto accidents
from shoulder strap which can cause
damage to median n. (between clavicle &
2nd rib)

Clavicle
aka shoulder blade, angel bone
 large, triangular, flat bone
 in superior part of posterior thorax
between levels of 2nd & 7th ribs


spine: prominent ridge that runs
diagonally across posterior surface
Scapula
lateral edge: acromion a flattened
expanded process, easily felt as hi pt of
shoulder (tailors use it as landmark to
measure length of arm)
 glenoid cavity: inferior to acromion,
smooth, shallow depression that accepts
head of humerus in shoulder joint

Scapula
Scapula
6 parts:
1. Humerus
2. Ulna
3. Radius
4. Carpals
5. Metacarpals
6. Phalanges

Upper Limb





Joints:
Shoulder
Elbow
Wrist
Hand
longest & largest bone of upper limb
 articulates proximally with scapula &
distally with ulna & radius
 head:
rounded proximal end
 articulates with glenoid cavity of
scapula to form glenohumeral joint

Humerus
Humerus
distal end:
 capitulum: rounded knob on lateral
aspect that articulates with head of
radius
 trochlea: medial to capitulum, spoolshaped, articulates with ulna

Humerus
Humerus
medial aspect of forearm
 longer than radius
 proximal end: olecranon (prominence in
elbow)
 distal end: head, styloid process
(posterior)

Ulna



Radius
lateral aspect of
forearm
proximal end: head
of radius:
articulates with
capitulum
distal end: styloid
process (palpable
proximal to thumb)
connect @ 3 places
1. interosseous
membrane
2. proximal end
3. distal end

Ulna & Radius



Carpals
proximal to the
hand, distal to
radius & ulna
8 small bones
joined by ligaments
articulations
w/each other
called intercarpal
joints
Carpal Tunnel
Metacarpals
14 bones of the digits (each hand)
 #’d I to V beginning with thumb
 thumb is the pollex has only 2
phalanges, other digits have 3
 joints between phalanges called
interphalangeal joints

Phalanges
Phalanges

2 hip bones (os coxa) which unite
anteriorly at pubic symphysis and
posteriorly with the sacrum @ sacroiliac
joint
Pelvic Girdle



Functions:
provides sturdy
support for
vertebral column
connects lower
limb to axial
skeleton
Pelvic Girdle
3 bones on each
side:
1. Ilium

◦
Pubis
2.
◦
3.

superior
anterior & inferior
Ischium
posterior &
inferior
Newborn Pelvis
largest of the 3 hip bones
 distinguishing features:
1. Iliac Crest
 along superior surface
1. Sacroiliac Joint (SI Joint)
 between sacrum and ilium

Ilium
Ilium
ramus of ischium fuses with pubis
 distinguishing features:

1.

Ischial Tuberosity
what you feel when someone sits on
your lap
Ischium
Ischium

Acetabulum
◦ formed by ilium, ischium, & pubis
◦ is the “socket” half of the hip joint

Pubic Symphysis
◦ joint between the 2 hip bones
Pubis

Pelvic Brim: line that distinguishes
between true & false palvis
True Pelvis/ False Pelvis
generally male bone heavier & stronger
& have larger surface marker (because
larger muscles attach)
 Pelvis:

◦
◦
◦
◦
deeper false pelvis, smaller, narrower
pelvic brim heart-shaped
acetabulum larger, faces posterior
obturator foramen round
Male Pelvis
generally bones lighter & thinner
 Pelvis:

◦
◦
◦
◦
false pelvis shallow, widers
pelvic brim larger, more oval
acetabulum smaller & faces anterior
obturator foramen oval
Female Pelvis
Male or Female?
Male or Female?








30 bones in each:
1 femur
1 patella
1 tibia
1 fibula
7 tarsals
5 metatarsals
14 phalanges
Lower Limb
longest, heaviest, & strongest bone in
the body
 proximally articulates with the
acetabulum to form hip joint

◦ Head of the Femur: “ball” part of joint
 small, central depression: fovea capitis
◦ Greater Trochanter
 prominence felt & seen @ side of hip
Femur
Femur

distally articulates with:
◦ Patella
◦ Tibia
Femur





small, triangular, sesamoid bone
develops in tendon of quadriceps femoris
muscle
Parts:
Base: broad, superior end
Apex: pointed, inferior end
Patella (kneecap)
Patella
“shin bone”
larger, medial, weight-bearing bone of
lower leg
proximally articulates with femur & fibula
distally articulates with fibula & tarsals
Tibia

Tibia
medial malleolus
forms prominence
that is palpable &
visible on medial
ankle



parallel & lateral to
the tibia &
considerably
smaller
head of fibula on
proximal end
lateral malleolus at
distal end
Fibula
Tibia & Fibula
7 bones:
 1 calcaneous: heel bone, largest of the
tarsals

Tarsals
5 bones between tarsals & phalanges
 #’d I to V from medial  lateral

Metatarsals
14 bones that make up the 5 digits
 #’d I to V medial to lateral
 Hallux: great or big toe has 2 large
heavy phalanges

Phalanges
2 arches in foot:
1. allows the foot to support weight of
body by distributing weight over the
soft & hard tissues
2. provide leverage while walking
fully developed by age 12 - 13

Arches of the Foot
Arches of the Foot

2 longitudinal
arches (medial &
lateral

1 transverse
arch
all skeletal tissue arises from mesoderm
 1st bone: skull in 4th wk
 U/S ~ 24 – 25 wks:

Development of the Skeletal System
Clubfoot:
1.
◦
◦
◦
inherited deformity in which baby is born with
foot twisted inferiorly & medially
1/1000 births
tx: casts or wraps, surgery may be indicated
Medical Terminology
2. Genu valgum:

knees
abnormally close
together with
increased space
between ankles
 aka “knock-knee”
Medical Terminology
3. Genu varum:
 knees abnormally
separated
 with lower limbs
bowed medially
 aka “bowleg”
Medical Terminology