chapter 8: the appendicular skeleton a&p biology 141

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