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

What are the bones of the pectoral girdle, their functions, and features? Figure 8–2a

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 The Scapular Head Holds glenoid cavity Which articulates with humerus To form shoulder joint Figure 8–3b

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 Posterior Features of the Scapula Scapular spine: ridge across posterior surface of body Separates 2 regions: supraspinous fossa infraspinous fossa

What are the bones of the upper limbs, their functions, and features? Arms, forearms, wrists, and hands Note: 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: Anatomical neck: Surgical neck: rounded, articulating surface contained within joint capsule Anatomical neck: margin of joint capsule Surgical neck: the narrow metaphysis

The Shaft The Distal Epiphysis Deltoid tuberosity: Radial groove: 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 Also called the antebrachium Consists of 2 long bones: ulna (medial) radius (lateral) Figure 8–5

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): Fingers: 2 phalanges (proximal, distal) Fingers: 3 phalanges (proximal, middle, distal)

What are the bones of the pelvic girdle, their functions, and features? Figure 8–7

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 Ilium Greater 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: Pubic symphysis: 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 PLAY 3D Rotation of Pelvis

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 smoother lighter less prominent muscle and ligament attachments PLAY Male and Female Pelvis

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? 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 Femur: The Shaft 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 Also called the shinbone Supports body weight Larger than fibula Medial to fibula Figure 8–13

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: Calcaneus (heel bone): Cuboid bone: 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: Medial cuneiform Intermediate cuneiform 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: Hallux: Other 4 toes: bones of the toes 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