Anatomy and Physiology I BIOL 2401 Chapter 8 The Skeletal System -Appendicular System

Skeletal System – Appendicular Skeleton Bones that make up upper and lower extremities Bones that make up pectoral and pelvic girdles 2

Appendicular Skeleton – Pectoral Girdle Attach upper extremities to the axial skeleton Bones include: Clavicles: articulate with scapula and sternum. Scapulae: articulate with the arm bone and the clavicle. 3

Appendicular Skeleton – Pectoral Girdle Clavicles: S shaped bones. Landmarks include: Medial sternal end - articulates with the manubrium of sternum. Forms sternoclavicular joint. Lateral acromial end - articulates with the acromion of scapula. Forms acromioclavicular joint. 4

Appendicular Skeleton – Pectoral Girdle Scapula: Flat, triangular shaped bone placed on the posterior surface of thorax. Landmarks include: Body: main part of scapula. Spine: a bony ridge that runs obliquely across the posterior surface. Acromion: a lateral, flat end of the spine; the high point of the shoulder. Coracoid process: a projection of the body just below the acromion; attachment site for muscles. Glenoid cavity: a cavity on the lateral border of the scapula; for articulation with head of humerus---forms glenohumeral joint (shoulder joint). 5

Appendicular Skeleton – Pectoral Girdle Scapula 6

Appendicular Skeleton – Upper Extremities 30 bones in each limb. Total of 60 bones. Consists of: Humerus Radius, Ulna Carpals Metacarpals Phalanges 7

Appendicular Skeleton – Upper Extremities Humerus Proximal end: Head: articulates with glenoid cavity of scapula. Greater and lesser tubercles: lateral and anterior projections just distal to anatomical neck. Intertubercular sulcus: groove between greater and lesser tubercles. 8

Appendicular Skeleton – Upper Extremities Humerus Body: shaft of the bone. Anatomical neck: just distal to head. Surgical neck: area distal to tubercles; humerus narrows. Deltoid tuberosity: lateral projection; attachment site for tendon of deltoid muscle 9

Appendicular Skeleton – Upper Extremities Humerus Distal end: Medial and lateral epicondyles: projections on the distal humerus; attachment points for muscles of the forearm. Capitulum: rounded structure on distal humerus (lateral); articulates with radius of forearm. Trochlea: medial to the capitulum; shaped like an hourglass on its side; articulates with the ulna. Olecranon fossa: posterior fossa that receives the olecranon process of the ulna. 10

Appendicular Skeleton – Upper Extremities Forearm Composed of the radius and the ulna Articulate with humerus to form elbow joint 11

Appendicular Skeleton – Upper Extremities Radius (Forearm) Lateral bone. Radial head: disc shaped; articulates with the capitulum of humerus. Radial tuberosity: bony projection medially located; attachment site for biceps brachii muscle 12

Appendicular Skeleton – Upper Extremities Ulna (Forearm) Medial bone. Trochlear notch: articulates with trochlea of humerus Coronoid process: anteriorly located; fits in coronoid fossa of humerus when elbow flexed (bent). Olecranon process: posteriorly located; forms the elbow point; fits into olecranon fossa of humerus when arm is bent. Styloid process: located on distal end. 13

Appendicular Skeleton – Upper Extremities Elbow Capitulum of humerus articulates with the head of radius. The trochlea of humerus articulates with the trocheal notch of ulna. The olecranon of ulna fits into the olecranon fossa on posterior surface of the humerus. 14

Appendicular Skeleton – Upper Extremities Made of 8 short bones called carpals. Arranged in two rows of four bones: Proximal: Scaphoid, Lunate, Triquetrum, Pisiform Distal: Trapezium, Trapezoid, Capitate, Hamate Wrist 15

Appendicular Skeleton – Upper Extremities Five in each palm. Long bones with proximal and distal ends. Proximal end: articulate with carpals. Distal end (head): articulate with finger bones; form the knuckles. Metacarpals 16

Appendicular Skeleton – Upper Extremities Composed of long bones called phalanges, each with proximal and distal ends. Three bones in each finger; two in thumb (pollex); a total of 14 phalanges in each hand. Fingers 17

Skeletal System – Appendicular Skeleton Lower extremities Pelvic girdle 18

Appendicular Skeleton – Pevic Girdle Pelvic Girdle: Attach lower extremities to the axial skeleton. Made of two flat bones called coxal bones. They articulate with each other and sacrum to form a ring. 19

Appendicular Skeleton – Pevic Girdle Coxal bone: Each coxal bone is formed by fusion of three bones: ilium, ischium and pubis. 20

Appendicular Skeleton – Pevic Girdle Coxal bone: Lower extremities articulate with acetabulum - a depression on lateral surface. Anteriorly, coxal bones articulate with each other – pubic symphysis. Posteriorly, coxal bones articulate with sacrum. 21

Appendicular Skeleton – Pevic Girdle Pelvic Girdle: Male vs. Female Male: Narrower Pelvic arch less than 90 degrees Larger, heavier Larger acetabulum Sacrum – longer, narrower Female: Wider—allows for childbirth Pelvic arch greater than 90 degrees Shallow, lighter Smaller acetabulum Sacrum – wider and shorter 22

Appendicular Skeleton – Lower Extremities 30 bones in each limb. Total of 60 bones. Consists of: Femur Tibia, fibula Tarsals Metatarsals Phalanges 23

Appendicular Skeleton – Lower Extremities Femur Proximal end: Head: articulates with acetabulum of coxal. Greater and lesser trochanter: lateral and anterior projections for muscle attachment. 24

Appendicular Skeleton – Lower Extremities Femur Neck- narrow area distal to head (common fracture site). Shaft: body of the bone. Linea aspera- attachment site for thigh muscles. 25

Appendicular Skeleton – Lower Extremities Femur Distal end: Medial and lateral epicondyles- attachment sites for knee ligaments Medial and lateral condyles- articulate with tibial condyles (held in place with menisci) Intercondylar fossa- found between condyles (posterior surface) Patellar surface- found on anterior surface 26

Appendicular Skeleton – Lower Extremities Patella Sesamoid bone. Protects knee joint. 27

Appendicular Skeleton – Lower Extremities Tibia Medial bone. Supports weight of body. Proximal end: Lateral and medial condyles: articulate with condyles of femur-tibiofemoral (knee) joint. Tibial tuberosity: for patellar ligament attachment. Distal end: Medial malleolus - distal end; medial ankle 28

Appendicular Skeleton – Lower Extremities Fibula Lateral bone. Proximal end: Head: articulate with proximal end of tibia (not femur). Distal end: Articulates with distal end of tibia. Lateral malleolus - distal end; lateral ankle. 29

Appendicular Skeleton – Lower Extremities Ankle/Foot Tarsals: ankle and heel bones; 7 short bones. Talus, calcaneous (heel bone), Navicular, Cuneiforms (lateral, intermediate, and medial), Cuboid. Metatarsals: 5 long bones; Proximal end: articulate with tarsals. Distal end: articulate with toe bones. Phalanges: make up toes. Each with proximal and distal ends. Three bones in each toe. Two in big toe (hallex). A total of 14 phalanges in each foot. 30

Appendicular Skeleton – Lower Extremities Foot arches Bones of foot are held in place by ligaments and tendons. They are arranged to form two arches: Longitudinal arch and transverse arch Function: Distribute body weight, act as a spring, support the body and provide leverage when walking. 31

Disorders Flat foot: Longitudinal arch decreased Club foot: Longitudinal arch increased Bunion: deformity of the big toe