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BIOL 301 (27)


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University of Waterloo
BIOL 301
Vivian Dayeh

CHAPTER 8 – THE APPENDICULAR SKELETON THE PECTORAL/SHOULDER GIRDLE − Posteriorly  consists of a scapula − Anteriorly  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 − Provides attachment for many muscles that move the limb. − 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 (scapula’s glenoid cavity) is shallow so it doesn’t restrict movement of humerus. Clavicles/collarbones − S-shaped bones o Sternal end attaches to manubrium medially. o Flattened acromial end articulates with scapula laterally. − Functions: 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 Scapulae/shoulder blades − Thin, triangular flat bones located on the dorsal surface of the rib cage between rib 2 superiorly and rib 7 inferiorly. − Each scapula has 3 borders: o Superior border  shortest and sharpest o Medial/vertebral border  parallel’s the vertebral column o Lateral/axillary border  abuts the axilla (armpit) and ends superiorly in a shallow fossa (the glenoid cavity)  This cavity articulates with humerus forming the shoulder joint. − Has 3 corners/angles: o Lateral angle  glenoid cavity lies here o Superior angle  superior and medial borders meet o Inferior angle  at the junction of the medial and lateral border.  Moves as the arm is raised and lowered − Coracoid process projects anteriorly from the lateral part of the superior scapular border. o It’s an attachment point for the biceps muscle of the arm. o Suprascapular notch lies medial to coracoids process; glenoid cavity is lateral to it. − Posterior surface bears a prominent spine that ends laterally in a flat projection called the acromion, which articulates with acromial end of the clavicle. − Also has large fossae: o Infraspinous fossa  lies inferior to scapular spine o Supraspinous fossa lies superior to scapular spine o Subscapular fossa  shallow concavity formed by the entire anterior surface of the scapula THE UPPER LIMB Arm/Brachium − 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 Forearm/antebrachium − 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 membrane. − In anatomical position, radius lies laterally (on thumb’s side) and ulna lies medially. − Ulna 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. − Radius 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 radioulnar joint. o Radial tuberosity  rough bump on anterior surfa
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