CHAPTER 8 â THE APPENDICULAR SKELETON
THE PECTORAL/SHOULDER GIRDLE
â Posteriorly ï consists of a scapula
â Anteriorly ï consists of clavicle
o Medial end of each clavicle joins to the sternum and first rib.
o Lateral ends of clavicle joins to scapulae at the shoulder
â Provides attachment for many muscles that move the limb.
â Mobility is due to:
o Because only clavicle attaches to the axial skeleton, the scapula can move quite
freely across the thorax, allowing the arm to move with it.
o Socket for the shoulder joint (scapulaâs glenoid cavity) is shallow so it doesnât
restrict movement of humerus.
â S-shaped bones
o Sternal end attaches to manubrium medially.
o Flattened acromial end articulates with scapula laterally.
o Provides attachment for muscles
o Act as braces: hold the scapulae and arms out laterally from the thorax
o Transmit compression forces from the upper limbs to axial skeleton
â Thin, triangular flat bones located on the dorsal surface of the rib cage between rib 2
superiorly and rib 7 inferiorly.
â Each scapula has 3 borders:
o Superior border ï shortest and sharpest
o Medial/vertebral border ï parallelâs the vertebral column
o Lateral/axillary border ï abuts the axilla (armpit) and ends superiorly in a shallow
fossa (the glenoid cavity)
ï§ This cavity articulates with humerus forming the shoulder joint.
â Has 3 corners/angles:
o Lateral angle ï glenoid cavity lies here
o Superior angle ï superior and medial borders meet
o Inferior angle ï at the junction of the medial and lateral border.
ï§ Moves as the arm is raised and lowered
â Coracoid process projects anteriorly from the lateral part of the superior scapular border.
o Itâs an attachment point for the biceps muscle of the arm.
o Suprascapular notch lies medial to coracoids process; glenoid cavity is lateral to
â Posterior surface bears a prominent spine that ends laterally in a flat projection called
the acromion, which articulates with acromial end of the clavicle.
â Also has large fossae:
o Infraspinous fossa ï lies inferior to scapular spine
o Supraspinous fossa ï lies superior to scapular spine
o Subscapular fossa ï shallow concavity formed by the entire anterior surface of
the scapula THE UPPER LIMB
â Humerus is only bone of arm
o Largest and longest bone in upper limb
o Articulates with scapula at shoulder and with radius and ulna at the elbow
â 2 parallel long bones: radius and ulna that articulate with humerus proximally and with
the wrist distally
o Interconnected along their entire length by flat ligament called interosseous
â In anatomical position, radius lies laterally (on thumbâs side) and ulna lies medially.
o Slightly longer than radius; main bone forming elbow joint with humerus.
o Proximal end has 2 prominent projections: olecranon and coronoid processes,
which are separated by the trochlear notch.
o Radial notch lies on lateral side of coronoid process, where the head of the
radius articulates with the ulna.
o Head of ulna articulates with radius distally.
o Thin at its proximal end and wider at distal end (opposite of ulna)
o Superior end articulates with capitulum of humerus.
o Medially, head of radius articulates with radial notch of ulna forming the proximal
o Radial tuberosity ï rough bump on anterior surfa