Bones of the Shoulder Girdle: Forensic Anthropology Overview

1. Forensic Anthropology

2. Bones of the Shoulder Girdle • The shoulder girdle provides support and anchor for the humerus and anchors a variety of muscles. It consists of the following bones: the clavicle and the scapula. http://www.kettering.edu/visitors/storypics/shoulder-joint.jpg

3. The clavicle - description • S–shaped bone • Articulates medially with manubrium of sternum • Articulates laterally with acromion of the scapula

4. The clavicle – what to know • Superior surface • Deltoid attachment • Trapezius attachment • Inferior surface • Acromial facet (lat) • Trapezoid ridge (a/i) • Conoid tubercle (p/i) • Subclavian groove • Costal pit (medial) http://www.sci.utah.edu/~simpson/documentation/projects/annotation/webdocs/image_gal_files/miscellaneous/clavicle.jpg

5. The clavicle – left from right • Superior surface smooth • Interior surface rough (subclavian groove) • Lateral end flatter (art with scapula) • Medial curve – posterior • Lateral curve – anterior

6. The scapula - description • The body of the scapula is large and triangular • Flat side is anterior side (to slide over ribs) • Articulates with the humerus at the glenoid fossa • Articulates with the clavicle at the acromion http://www.kettering.edu/visitors/storypics/shoulder-joint.jpg

7. The scapula – what to know • Anterior/costal surface • Body • 3 borders • Medial/vertebral • Lateral/axillary • superior • Coracoid process (smaller, anterior) • Scapular notch (superior) • Glenoid fossa http://www.alignmed.com/images/Scapula_1.jpg

8. The scapula – what to know • Posterior/dorsal surface • Scapular spine • 3 borders • Medial/vertebral • Lateral/axillary • Superior • Acromion process (higher and wider) • Supraspinous and infraspinous processes http://content.answers.com/main/content/img/oxford/Oxford_Sports/0199210896.scapula.1.jpg

9. The scapula – left from right • Orient the spine posteriorly • Put the point down • Glenoid fossa is lateral

10. Bones of the thorax • The thorax (or chest) is like a cage made of cartilage and bone. This cage protects the main organs of the circulatory and respiratory systems, and is the base to which the upper limbs are attached. http://home.comcast.net/~wnor/thoraxbones.htm

11. The sternum - description • Manubrium – widened superior portion • Jugular notch at top, art. w/ BOTH clavicles, cartilage of BOTH 1st ribs attach only at manubrium

12. The sternum - description • Body – long medium width bone attach at inferior portion of manubrium, cartilage of ribs 3-7 attache to body of sternum • Xiphoid process – small inferior portion of sternum – attachment for abdomen muscles http://home.comcast.net/~wnor/thoraxbones.htm

13. The sternum – what to know • Manubrium • Jugular notch • Clavicular notch • Costal notches • Body of the sternum • Costal notches • Xiphoid process • Can be fused to sternal body in some cases

14. The ribs - description • 24 total (though there may be variation in the number) • Function – protect thoracic organs • Each rib articulates with a thoracic vertebrae and has an extension of cartilage anteriorly • Ribs 1-7 are true ribs (direct art. w/ sternum) • Ribs 8-10 are false ribs (indirect art.) • Ribs 11-12 are floating ribs (no art. w/ sternum)

16. The ribs – what to know • Head – single or double facet • Articulates with lateral vert body • Neck • Tubercle – single facet • Articulates with transverse process of vert (ribs 1-9/10) • Shaft/body • Angle • Costal groove • Sternal end • Ribs 1-7 wide, 8-10 tapered, 11-12 flat

17. The ribs – how to sort • Rib cage barrel-shaped • Easiest to sort… • 1st rib; short, flat, steep curve, long neck Inner surface inferior • 11th and 12th ribs; fan-shaped head, no neck, tapered ends, 12th VERY short Inner surface superior

18. The ribs – sorting the rest • Head shape changes to fan shaped • Neck length shortens • Curvature changes – but each rib conforms to the curvature of adjacent ribs

19. The ribs - sorting • Figure 4.12b in book • ~ 1-4 long necks • ~ 5-9 double faceted head • ~ 7-9 wide head • ~ 9-12 no neck • ~ 11-12 no tubercle http://home.comcast.net/~wnor/thoraxbones.htm

21. The ribs – left from right • Head posterior – articulates with vertebrae • Sternal end anterior • Sharp ridge inferior

22. Comprised of 3 bones Humerus Radius Ulna Useful for ALL useful for age/growth Handedness Sex determination ? stature determination Skeletal anatomy of the arm

23. The humerus - description • Longest, most robust bone of the arm • Contains the Ball of the Ball and socket joint • Articulations: • Proximal – head of the humerus with the glenoid cavity of scapula • Distal – radius and ulna with the capitulum and trochlea (resp.) • Shape = cylindrical shaft • Round, articular proximal end • Broad, flattened distal end

25. Proximal end: Head – points medially Greater tubercle – anterolaterally Lesser tubercle – anterior Neck – narrowest area Deltoid tuberosity – lateral attach of deltoid m. Distal end: Medial and lateral epicondyle (Med. Larger) Fossas – named for what depression receives Olecranon – posterior Coronoid - anterior Capitulum – rounded Art. w/ radial head Joint - rotation Trochlea – large, spool-like Art. w/ ulna at olecranon process Joint – flexion/extension The humerus – What to know

26. Humerus – Right from left • Orient humeral head superior (points medially) • Make sure tubercles are anterior • Make sure trochlea and capitulum are anterior and distal • Olecranonfossa is posterior • Larger of the 2 epicondyles is MEDIAL

27. The radius - description • Lateral to the ulna, more robust • Responsible for ROTATION

28. The Radius • Shaft – teardrop X-section, • broadens • Round head proximally • Full-length interosseous ridge on medial surface • Articulations • Proximal - radial head with capitulum of humerus AND radial notch of ulna • Distal - distal radial articular area with scaphoid and lunate AND ulnar notch of radius with distal ulna

30. Proximal End: Head – art. at capit and radial notch Neck – narrow area Radial tuberosity – anterio-medially orient. attach of biceps m. Distal End: Styloid process – lateral Ulnar notch – postero-medial area of art. w/ulna Dorsal tubercle – posterior Distal articular area art. w/ scaphoid and lunate The Radius – What to know

31. Radius – Right from left • Orient radial head superior • Make sure the radial tuberosity, ulnar notch and interosseous crest are medial (i.e. point toward the ulna and the interosseous space….) • Dorsal tubercle is posterior (i.e. dorsal….) • Styloid process is lateral

32. The Ulna - description • Medial to the radius, more slender; parallel to radius when arm supine • Responsible for flexion/extension AND stability at elbow joint

33. The Ulna • Articulations • Proximal - Olecranon process with trochlea of humerus AND with radial head at radial notch of ulna • Distal - Ulnar head art. w/ ulnar notch of radius; ? Art. with lunate but separated by articular disk for ↑flexibility • Shape = teardrop shaft • Hook-shaped proximally • Narrow head distally

34. Proximally: Olecranon process Semilunar notch Coronoid process – anteri-medial Radial notch – lateral art. w/ radial head Distally: Head – art. w/ radial ulnar notch Styloid process – medial The Ulna – What to know

35. The Ulna – Right from left • Orient the olecranon process superior and the semilunar notch is anterior • Make sure the radial notch and the interosseous crest are lateral • The head is distal • The styloid process is medial