Download Period 2 Pectoral girdle and upper limb

Pectoral Girdle & Upper Limb
Sarah Derman
Irene Park
Tom Raday
Jenn Suh
Overview
• Part of the
appendicular division
-bones of the upper
and lower limbs
-supporting and
connecting bones of
the pectoral and
pelvic girdles
PECTORAL GIRDLE
• Two slender, curved clavicles (collarbones) & two
broad, flat scapulae
• Functions: Position the shoulder joint + provide a
base for arm movement
• Surfaces of scapulae and clavicles are sites for
muscle attachment
-muscles attached to the pectoral girdle help move
the arm
Clavicle
• S-shaped
• Smooth, superior surface lies just beneath the
skin
• Rough, interior surface of the acromial end has
lines and tubules as muscle attachment sites
Right clavicle in a
superior view
Acromial end
Clavicle
• Only direct connections between the axial
skeleton and the pectoral girdle
• Articulates with the manubrium of the sternum
at its strenal end + the acromion (process) of
the scapula at its acromial end
Clavicle
• Small and fragile  fractures are common but
heal rapidly without a cast
• Ex. Simple fall with outstretched arm
 fractured clavicle
(“broken collarbone”)
Scapula
• Anterior surface of the body of
the scapula forms a triangle bounded by the
superior, medial, and lateral borders
-Skeletal muscles support and position the
scapula by attaching along these borders
(scapula has no bony or ligamentous connection
to the thoracic cage)
Scapula
Right scapula
Scapula
• Head of scapula at the intersection of the
lateral and superior borders forms a process
that supports the shallow, cup-shaped glenoid
cavity (glenoid fossa)
-At the glenoid cavity,
the scapula articulates with
the proximal end
of the humerus to form
the shoulder joint
Scapula
Right scapula
Scapula
• Subscapular fossa: Depression in the anterior
surface of the body of the scapula
-Subscapularis muscle attaches to the
subscapular fossa + to the humerus (the
proximal bone of the upper limb)
Scapula
UPPER LIMB
• Skeleton = bones of the…
-arm (brachium): from shoulder to elbow; contains
a single bone (humerus) that extends from the
scapula to the elbow
-forearm (radius and ulna)
-wrist (carpal bones)
-hand
(metacarpal bones
and phalanges)
Humerus (Arm)
TOP
• Head articulates with
the scapula
• Greater tubercle: rounded projection near the
lateral surface of the head
-gives shoulder its lateral contour
• Lesser tubercule: lies more anteriorly; separated
from the greater tubercle by a deep
intertubercular groove
• Muscles are attached to both tubercules
-large tendon runs along the groove
Humerus (Arm)
TOP
• Anatomical neck: lies between the tubercules and
below the surface of the head
• Surgical neck: lies distal to the tubercles
-narrow
-common fracture site
(damage to axillary
nerve and artery
causes muscles
to malfunction)
Humerus (Arm)
MIDDLE
• Shaft: round in section
• Deltoid tuberosity:
runs along the lateral
border of the shaft
-deltoid muscle
attaches to deltoid
tuberosity
BOTTOM
• Shaft flattens and expands to either side, forming a broad
triangle
• Medial and lateral epicondyles project to either side
• -surface area for muscle attachment
• Condyle dominates the inferior surface of the humerus
-at condyle: humermus articulates with the bones of the
forearm, the radius, and the ulna
-two distinct regions
1) trochlea: large medial portion
shaped like a spool or pulley
2) capitulum: lateral region of
the condyle
-radial fossa accepts projection
from radius
Ulna (Forearm)
• Ulna=medial support of the forearm
• Olecranon: point of the elbow (of ulna)
-trochlear notch articulates with the
trochlea of the humerus at the elbow joint;
-limit of the extension (arm + forearm form
a straight line)
-limit of flexion (arm + forearm form a V)
• Radial notch: lateral to the coronoid
process; accomdates the head of the
radius
• Styloid process: where the ulna ends
-stabilizes the joint by preventing lateral
movement of the carpal bones of the wrist
Radius (Forearm)
• Radius=lateral (thumb) side
of the forearm
-Fibrous sheet connects the
ulna to the radius
• Narrow neck extends from the
head to the radial tuberosity
(attachment site of the biceps
brachii)
-head articulates with the
capitulum of the humerus at
the elbow joint & with radical
notch of the ulna  radius
rolls across the ulna (rotating
palm movement)
Wrist and Hand
• Wrist, palm, fingers: 27 bones
-8 carpal bones (wrist/carpus): scaphoid, lunate,
triquetrum pisiform, trapezium, trapezoid, capitates,
hamate
-5 metacarpal bones (palm): articulate with
the distal carpal bones
-14 phalangeal bones
(phalange=finger bone): articulate with
the metacarpal bones
-four fingers have three phalanges each
-thumb (pollex) has two phalanges
Upper Limb
• Upper Limb Disorders (ULDs): affect the arms,
from finger to shoulder, and neck
• Aches, pains, tension, and disorders
• Problems with muscles, tendons, ligaments
• Caused or made worse by repetitive,
uncomfortable work that involves excessive
force
• Prevention: exercise, breaks, good posture