Forensic Anthropology. Bones of the Shoulder Girdle The shoulder girdle provides support and anchor...

Forensic Anthropology

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

The clavicle - description S–shaped bone Articulates

medially with manubrium of sternum

Articulates laterally with acromion of the scapula

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

The clavicle – left from right

Superior surface smooth Interior surface rough (sub clavian groove) Lateral end flatter (art with scapula) Medial curve – posterior Lateral curve – anterior

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

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

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

The scapula – left from right

Orient the spine posteriorly

Put the point down

Glenoid fossa is lateral

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

The sternum - description Manubrium – widened

superior portion Jugular notch at top, art.

w/ BOTH clavicles, cartilage of BOTH 1st ribs attach only at manubrium

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

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

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)

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

The ribs – how to sort

Rib cage barrel-shaped Easiest to sort…

1st rib; short, flat, steep curve, long neckInner surface inferior

11th and 12th ribs; fan-shaped head, no neck, tapered ends, 12th VERY short

Inner surface superior

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

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

The ribs – left from right

Head posterior – articulates with vertebrae

Sternal end anterior

Sharp ridge inferior

Skeletal anatomy of the armComprised of 3 bones

Humerus Radius Ulna

Useful for ALL useful for age/growth Handedness Sex determination ? stature determination

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

The humerus – What to know 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

Humerus – Right from left Orient humeral head superior (points

medially) Make sure tubercles are anterior Make sure trochlea and capitulum are

anterior and distal Olecranon fossa is posterior Larger of the 2 epicondyles is MEDIAL

The radius - description

Lateral to the ulna, more robust

Responsible for ROTATION

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

The Radius – What to know

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

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

The Ulna - description

Medial to the radius, more slender; parallel to radius when arm supine

Responsible for

flexion/extension AND

stability at elbow joint

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

The Ulna – What to know

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 – 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