Chapter 7

1. Chapter 7 Pectoral Girdle and Upper Limbs

2. Pectoral Girdle • Composed of 2 clavicles (collar bones) and 2 scapulae (shoulder blades) • Supports upper limbs • Serves as an attachment point for muscles

3. Clavicles • Slender, rod-like bones with elongated S-shapes • Run horizontally between the sternum and the shoulders • The sternal, or medial, ends articultate with the manubrium (of the sternum) • The acromial, or lateral, ends join the processes of the scapulae • Structurally very weak • Brace the scapulae and help to hold the shoulders in place • Provide attachments for muscles of the upper limbs, chest, and back

4. Scapulae • Broad, triangular bones • Located on either side of the upper back • Have flat bodies with concave anterior surfaces • Three borders of the scapula are labeled as: superior border, axillary or lateral border, and veterbral or medial border

5. Scapulae • Special features: • Posterior surface is divided into unequal portions by a spine • The spine leads to the acromion process that forms the tip of the shoulder, articulates with the clavicle, and provides attachments for muscles of the upper limbs and chest • The coracoid process curves anteriorly and inferiorly to the acromion process and also provides attachments for muscles of the upper limbs and chest • Between the two processes on the lateral surface is a depression called the glenoid cavity that articulates with the head of the arm bone • Supraspinousfossa is located above the spine • Infraspinousfossa is located below the spine

6. Upper Limb • Bones of the arm, forearm, and hand • Includes humerus, radius, ulna, carpals, metacarpals, and phalanges • Provide attachments for muscles • Interact with muscles to move limb parts

7. Humerus • Long bone that extends from the scapula to the elbow • Special features: • Head • Located at the upper end • Smooth and round • Fits into the glenoid cavity of the scapula • Greater tubercle and lesser tubercle • Located below the head (greater tubercle on the lateral side and lesser tubercle on the anterior side) • Serve as attachments for muscles that move the upper limb at the shoulder • Intertubular groove • Narrow furrow located between the two processes • Serve as a passage for a tendon that passes from the biceps brachii (a muscle in the arm) to the shoulder

8. Humerus • Special Features (cont) • Anatomical neck • Narrow depression along the lower margin of the head that separates it from the tubercules • Surgical neck • Tapering region just below the head and the tubercules • Deltoid tuberosity • Rough V-shaped area near the middle of the bony shaft on the lateral side • Provides an attachment for the deltoid muscle that raises the upper limb horizontally to the side

9. Humerus • Special features (cont) • Capitulum • Knob-like condyle on the lateral side of the lower end of the humerus • Articulates with the radius at the elbow • Trochlea • Pulley-shaped condyle on the medial side of the lower end of the humerus • Articulates with the ulna at the elbow • Epicondyles • Located above the condyles on either side • Provide attachments for muscles and ligaments of the elbow • Coronoidfossa • Depression located between the epicondylesanteriorly • Receives the coronoid process of the ulna when the elbow bends • Olecranonfoassa • Depression located between the epicondylesposteriotly • Receives the olecranon process when the elbow straightens

10. Radius • Located on the thumb side of the forearm • A little bit shorter than the ulna • Crosses over the ulna when the hand is turned so that the palm faces backwards • Special features: • Head • Disc-like • Located at the upper end of the radius • Articulates with capitulum of the humerus and the radial notch of the ulna • Allows the radius to rotate • Radial tuberosity • Process located just below the head • Attachment for the biceps brachii which bends the upper limb at the elbow • Styloid • Located at the distal end • Provides attachments for ligaments of the wrist

11. Ulna • Second bone in the forearm • Overlaps the end of the humerusposteriorly • Special features: • Head • Located at the distal end • Articulates laterally with the ulnar notch of the radius • Articualtes inferiorly with a disc of fibrocartilage which joins the triquetrum (wrist bone) • Trochlear (semilunal) notch • Wrenchlike opening located at the proximal end • Articultes with the trochea of the humerus

12. Ulna • Special features (cont): • Olecranonprocess • Located above the trochlear notch • Provides an attachment for the triceps brachii that straightens the upper limb at the elbow • Fits into the olecranonfossa of the humerus when the elbow is straightened • Coronoid process • Located just below the trochlear notch • Fits into the coronoidfossa of the humerus when the elbow is bent • Styloid process • Located at the distal end • Provides attachements for ligaments of the wrist

13. Hand • Consists of the wrist, palm, and fingers • Wrist: • Contains 8 small carpal bones • Carpal bones are arranged in 2 rows of 4 bones (with the resulting structure called a carpus) • The carpus is rounded on its proximal surface where it articulates with the radius and the fibrocartilaginous disc on the ulnar side • The carpus is concave anteriorly and forms a canal through which tendons and nerves extend to the palm • The distal surface of the carpus articulates with the metacarpal bones

14. Hand • Palm (metacarpus) • Formed by 5 metacarpal bones (one in line with each finger) • Bones are cylindrical • Rounded distal ends of the bones form nuckles • Metacarpals articulate proximally with the carpals and distally with the phalanges • Lateral side of the metarcarpal is the most freely moveable, permitting the thumb to oppose the finger when grasping something • Bones are numbered 1 to 5, beginning with the metacarpal of the thumb

15. Hand • Phalanges • 14 Finger bones • 3 in each finger (proximal, middle, and distal phalanx) • 2 in the thumb (lacking a middle phalanx)