BIO 5, CH.8 - APPENDICULAR SKELETON

Appendicular Skeleton

bones of the limbs + girdles of bones that attach limbs to axial skeleton

Bones of the Appendicular Skeleton

63 bones per each side of the body, 126 bones total

Pectoral Girdle

articulates with the trunk and supports the upper limbs (4 bones total)

– Clavicles (2)

– Scapulae (2)

Clavicle Bone

• s-shaped bone

• articulates medially with the manubrium of sternum and laterally with the acromion

• conoid tubercle on inferior surface

Scapula

a broad, flat triangle

– Three borders and three angles

• Glenoid cavity articulates with head of humerus

• Other features (for muscle and ligament attachment):

– Posterior: Bony ridge = spine

• Supraspinous fossa is above it; infraspinous fossa is below it

– Lateral: Acromion process

– Anterior projection: Coracoid process

– Subscapular fossa is anterior surface

Upper Limbs

• humerus in brachium (upper arm)

• radius and ulna in antebrachium (forearm)

• 8 carpal bones in wrist

• 5 metacarpals in palm

• 14 phalanges in fingers

Humerus

• Proximal features: (2)

– head: articulates with scapula

– anatomical and surgical necks

– greater and lesser tubercles: for muscle attachment

– intertubercular sulcus: for passage of biceps brachii tendon and muscle attachment

Shaft of Humerus

deltoid tuberosity for attachment of deltoid muscle

Radius

– Proximal features:(2)

• head: articulates with capitulum of humerus

• neck: narrowest region

• radial tuberosity: for biceps brachii muscle attachment

– Distal features:

• styloid process: lateral “wrist bump”

•medial dent for head of ulna

Ulna

– Proximal features:(2)

• trochlear notch: accommodates trochlea of humerus

• olecranon: projection that forms the posterior “bump” of the elbow; attachment site for triceps brachii

• coronoid process: inferior lip of trochlear notch

• radial notch: lateral; accommodates head of radius

– Distal features:

• head: knoblike end

• styloid process: posteromedial “wrist bump”

Supination

when the palm of the hand faces up

Pronation

when the palm of the hand faces down

1. Carpal Bones: Proximal Row (S)

Scaphoid

2. Carpal Bones: Proximal Row (L)

Lunate

3. Carpal Bones: Proximal Row (T)

Triquetrum

4. Carpal Bones: Proximal Row (P)

Pisiform

5. Carpal Bones: Distal Row (Tm)

Trapezium

6. Carpal Bones: Distal Row (Td)

Trapezoid

7. Carpal Bones: Distal Row (C)

Capitate

8. Carpal Bones: Distal Row (H)

Hamate

Carpals

8 wrist bones, two rows (1 proximal & 1 distal) of four

Metacarpals

5 in the palm, named by Roman numerals I–V

I is the base of the thumb, V is the base of the little finger

Phalanges

14 per hand, 3 phalanges per finger

• Proximal, middle, & distal phalanges

2 in the thumb (pollex)

• Proximal & distal phalanges (no middle phalanx)