chapter 8: the appendicular skeleton a&p biology 141
TRANSCRIPT
Chapter 8:The Appendicular Skeleton
A&P Biology 141
The Appendicular Skeleton
Figure 8–1
The Appendicular Skeleton
• Allows us to move and manipulate objects• Includes all bones besides axial skeleton:
– the limbs – the supportive girdles
The Pectoral Girdle
Figure 8–2a
What are the bones of the pectoral girdle, their functions, and features?
The Pectoral Girdle
• Also called the shoulder girdle• Connects the arms to the body • Positions the shoulders• Provides a base for arm movement• Consists of:
– 2 clavicles – 2 scapulae
• Connects with the axial skeleton only at the manubrium
The Clavicles
Figure 8–2b, c
The Clavicles
• Also called collarbones• Long, S-shaped bones• Originate at the manubrium (sternal end)• Articulate with the scapulae (acromial end)
The Scapulae
• Also called shoulder blades• Broad, flat triangles• Articulate with arm and collarbone
The Scapula
• Anterior surface: the subscapular fossa
Figure 8–3a
Structures of the Scapula• Body has 3 sides:
– superior border– medial border (vertebral border)– lateral border (axillary border)
• Body has 3 corners:– superior angle– inferior angle– lateral angle
Structures of the Scapula
Figure 8–3b
The Scapular Head
•Holds glenoid cavity •Which articulates with humerus
•To form shoulder joint
Processes of the Glenoid Cavity
• Coracoid process:– anterior, smaller
• Acromion: – posterior, larger – articulates with clavicle– at the acromioclavicular joint
Structures of the Scapula
• Posterior surface
Scapular spine:ridge across posterior surface of bodySeparates 2 regions: supraspinous fossa infraspinous fossa
Posterior Features of the Scapula
What are the bones of the upper limbs, their
functions, and features?
• The Upper Limbs• Arms, forearms, wrists,
and handsNote: arm (brachium)
1 bone - the Humerus
The Humerus
• Also called the arm • The long, upper armbone• Articulates with the pelvic girdle
Tubercles of the Proximal Epiphysis
• Separated by the intertubercular groove:– greater tubercle:
• lateral• forms tip of shoulder
– lesser tubercle: • anterior, medial
Head and Neck
• Head:– rounded, articulating surface– contained within joint capsule
• Anatomical neck:– margin of joint capsule
• Surgical neck:– the narrow metaphysis
The Shaft• Deltoid tuberosity:
– a bulge in the shaft– attaches deltoid muscle
• Radial groove:– for radial nerve– posterior to deltoid tuberosity
– The Distal Epiphysis• Medial and lateral epicondyles:
– for muscle attachment
• Condyle of the humerus:– articulates with ulna and radius
Articular Regions of the Condyle
• Trochlea:– coronoid fossa and olecranon fossa – articulates with ulna
• Capitulum:– radial fossa– articulates with radius
The Forearm
Figure 8–5
Also called the antebrachiumConsists of 2 long bones:
ulna (medial)radius (lateral)
Ulna: The Olecranon
• Superior end of ulna • Point of elbow• Superior lip of trochlear notch• Articulates with trochlea of humerus
Ulna: The Coronoid Process• Inferior lip of trochlear notch
Ulna: Articulations with the Humerus
• Forearm extended: – olecranon enters olecranon fossa
• Forearm flexed:– coronoid process enters coronoid fossa
Ulna: Other Articulations• Radial notch:
– articulates with head of radius– forms proximal radioulnar joint
• Ulnar head:– prominent styloid process– attaches to articular disc between forearm and wrist
Interosseous Membrane• A fibrous sheet• Connects lateral margin of ulnar shaft to radius
The Radius
• Lateral bone of forearm• Disk-shaped radial head above the neck• Radial tuberosity below the neck, attaches
biceps
Articulations of the Radius
• Ulnar notch:– distal end– articulates with wrist and radius
• Styloid process:– stabilizes wrist joint
The Wrist
Figure 8–6
The Wrist
• 8 carpal bones:– 4 proximal carpal bones – 4 distal carpal bones – allow wrist to bend and twist
The 4 Proximal Carpal Bones
• Scaphoid bone:– near styloid process
• Lunate bone:– medial to scaphoid
• Triquetrum:– medial to lunate bone
• Pisiform bone:– anterior to triquetrum
The 4 Distal Carpal Bones
• Trapezium:– lateral
• Trapezoid bone:– medial to trapezium
• Capitate bone:– largest
• Hamate bone:– medial, distal
Metacarpal Bones
• The 5 long bones of the hand • Numbered I–V from lateral (thumb) to
medial• Articulate with proximal phalanges
Phalanges of the Hands
• Pollex (thumb):– 2 phalanges (proximal, distal)
• Fingers:– 3 phalanges (proximal, middle, distal)
The Pelvic Girdle
Figure 8–7
What are the bones of the pelvic girdle, their functions, and features?
The Pelvic Girdle
• Made up of 2 hipbones (ossa coxae)• Strong to bear body weight, stress of
movement• Part of the pelvis
Os Coxae• Made up of 3 fused bones:
– ilium (articulates with sacrum)– ischium– pubis
The Acetabulum
• Also called the hip socket• Is the meeting point of the ilium, ischium, and
pubis • Is on the lateral surface of the os coxae • Articulates with head of the femur (lunate
surface)
Acetabular Notch• A gap in the ridge of the margins of the
acetabulum
•Marks of the IliumGreater sciatic notch:
for sciatic nerve• Marks of the Ischium• Ischial spine:
– above lesser sciatic notch• Ischial tuberosity:
– posterior projection you sit on • Ischial ramus:
– meets inferior ramus of pubis
Marks of the Pubis
• Superior ramus:– meets pubic tubercle
• Pubic symphysis:– gap between pubic tubercles– padded with fibrocartilage
Marks of the Pelvic Girdle
• Obturator foramen:– formed by ischial and pubic rami– attaches hip muscles
• Pectineal line:– ridge of superior ramus of pubis– continues to iliac crest as arcuate line
• Iliac fossa:– depression between ileac crest and arcuate
line
Articulations of the Pelvic Girdle
• Sacroiliac joint:– articulation of posterior auricular surface of
ilium– with the sacrum– stabilized by ligaments of iliac tuberosity
The Pelvis
Figure 8–8
The Pelvis
• Consists of 2 ossa coxae, the sacrum, and the coccyx
• Stabilized by ligaments of pelvic girdle, sacrum, and lumbar vertebrae
3D Rotation of PelvisPLAY
Divisions of the Pelvis
Figure 8–9
Divisions of the Pelvis• * True pelvis:
– encloses pelvic cavity-• Pelvic brim:
– upper edge of true pelvis – encloses pelvic inlet
• Perineum region:– inferior edges of true pelvis– forms pelvic outlet– perineal muscles support organs of pelvic cavity
• False pelvis:– blades of ilium above arcuate line
What are the structural and functional differences between
the male and female pelvis?
Comparing the Male and Female Pelvis
Figure 8–10
Comparing the Male and Female Pelvis
• Female pelvis:– smoother– lighter– less prominent muscle and ligament
attachments
Male and Female PelvisPLAY
Pelvis Modifications for Childbearing
• Enlarged pelvic outlet• Broad pubic angle (> 100°)• Less curvature of sacrum and coccyx• Wide, circular pelvic inlet• Broad, low pelvis• Ilia project laterally, not upwards
What are the bones of the lower limbs, their
functions, and features?
The Lower Limbs• Functions:
– weight bearing– motion
Note: leg = lower leg; thigh = upper leg
Bones of the Lower Limbs
• Femur (thigh)• Patella (kneecap)• Tibia and fibula (leg)• Tarsals (ankle)• Metatarsals (foot)• Phalanges (toes)
The Femur
• The longest, heaviest bone
Figure 8–11
Femur: The Proximal Epiphysis
• Femoral head:– articulates with pelvis at acetabulum– attaches at fovea capitis
Femur: The Neck• Narrow area between head and
trochanters• Joins shaft at angle
Femur: Trochanters• Greater and lesser trochanters:
– tendon attachments• Intertrochanteric line (anterior) and
intertrochanteric crest (posterior):– mark edge of articular capsule
Femur: The Shaft• Linea aspera:
– most prominent ridge of shaft– attaches hip muscles– joins epicondyles
Femur: The Distal Epiphysis
• Medial and lateral epicondyles: – above the knee joint
• Medial and lateral condyles:– separated by intercondylar fossa and patellar
surface– form part of knee joint
The Patella
Figure 8–12
The Patella
• Also called the kneecap• A sesamoid bone• Formed within tendon of quadriceps
femoris• Base attaches quadriceps femoris• Apex attaches patellar ligament
The Tibia
Figure 8–13
• Also called the shinbone
• Supports body weight
• Larger than fibula
• Medial to fibula
Tibia: The Proximal Epiphysis
• Medial and lateral tibial condyles: – separated by intercondylar eminence – articulate with medial and lateral condyles of
femur• Tibial tuberosity:
– attaches patellar ligament
Tibia: The Shaft• Anterior margin:
– sharp ridge of shinbone
Tibia: The Distal Epiphysis
• Medial malleolus:– medial projection at the ankle
The Fibula
• Attaches muscles of feet and toes• Smaller than tibia• Lateral to tibia
Fibula: Articulations with Tibia
• Fibula/tibia articulations:– head– inferior tibiofibular joint
• Interosseous membrane:– binds fibula to tibia
• Lateral malleolus:– lateral projection of ankle
The Ankle
• Also called the tarsus:– consists of 7 tarsal
bones
Figure 8–14a
Bones of the Ankle
• Talus:– carries weight from tibia across trochlea
• Calcaneus (heel bone):– transfers weight from talus to ground– attaches Achilles tendon
• Cuboid bone:– articulates with calcaneus
Ankle Bones
• Navicular bone:– articulates with talus and 3 cuneiform bones
• Medial cuneiform• Intermediate cuneiform• Lateral cuneiform
Feet: Metatarsal Bones
• 5 long bones of foot • Numbered I–V, medial to lateral• Articulate with toes
Feet: Phalanges
• Phalanges: – bones of the toes
• Hallux:– big toe, 2 phalanges (distal, proximal)
• Other 4 toes:– 3 phalanges (distal, medial, proximal)
Feet: Arches
• Arches transfer weight from 1 part of the foot to another
Figure 8–14b
Feet: The Longitudinal Arch
• Calcanear portion:– lateral
• Talar portion:– Medial
Feet: The Transverse Arch• Formed by a difference in curvature
between medial and lateral borders of the foot
KEY CONCEPT
• Pectoral girdle is highly mobile, stabilized primarily by muscles
• Pelvic girdle is more massive, stronger, and less mobile
How does the skeleton reveal significant
information about an individual?
Studying the Skeleton
• Reveals characteristics:– muscle strength and mass (bone ridges, bone
mass)– medical history (condition of teeth, healed
fractures)– sex and age (bone measurements and fusion)– body size
What are the skeletal differences between males and females?
Male and Female Skeletons
Table 8–1
How does aging affect the skeletal system?
Age-Related Skeletal Changes
Table 8–2
SUMMARY (1 of 3)
• Components of the:– appendicular skeleton– pectoral girdle, and relationship to axial
skeleton– upper limbs, and relationship to pectoral girdle
SUMMARY (2 of 3)
• Components of the:– pelvic girdle, and relationship to axial skeleton– lower limbs, and relationship to pelvic girdle
SUMMARY (3 of 3)
• Differences between male and female pelvises
• Individual skeletal variations • Effects of aging