THE UPPER LIMB

The Upper limb: Pectoral girdle+The arm


CLAVICLE

is like a CRANE

scapula and the free limb are suspended off this crane

it keeps the limb AWAY from the trunk

so the limb can move freely- increases

the range of motion

FIND:

acromium

lateral ⅓

medial 2/3

sternal end

SCAPULA

Is a Triangle!

A FLAT (ish) triangle

Surfaces:

Posterior & Anterior

Borders: 

Superior (at the top)

Axillary (near the armpit)

Vertebral (medial, near the midline, near spine)

Angles:

Superior (top angle)

Inferior (bottom, under angle)

Lateral (side angle)

Projections: 

Are for attachments, thus they stick out

What attaches to le scapula?
(well, what doesnt?)

Achromion (for clavicle)

Coracoid process and spine (for muscles)

HUMERUS

find:

the upper end

shaft

the lower end

*******Workshop QUESTIONS********

Deduce (from the shape of the articular surfaces) the movements permitted at the:

(i) joints of the clavicle

(ii) shoulder joint

(iii) elbow joint (next week)

Are these joints more likely to be mobile or stabilising?

What stabilises them?

***STERNOCLAVICULAR JOINT***

tightly wrapped sandwich in a box

ARTICULAR DISC sandwiched between CLAVICLE and

the MANUBRUM (of STERNUM)

TIGHTLY wrapped by ligaments at the front and back 

(anterior and posterior sternoclavicular ligaments)

in a BOX of joint capsule

attached to the other clavicle through interclavicular ligament

more STABLE or more MOBILE?

This is the joint that attaches axial skeleton to the appendicular skeleton,
as in, the body to the limbs

it needs to be effing solid and stable

but..
IT also allows movements OF THE PECTORAL GIRDLE AND THE upper LIMB

See figure on Moore, p. 794

MOVES THE LATERAL END OF THE CLAVICLE

There is a DISC in the middle.

What is it for?

Injury: Quite uncommon because it's very strong

ACROMIOCLAVICULAR JOINT

Acromium of scapula-Clavicle

Plane Joint

acromium end(covered by FC)-disc-clavicle end(covered by FC)

WHY fibrocart instead of hyaline?

Movement:

Rotation of the acromial end of the clavicle 

Injury: Shoulder separation

SHOULDER (GLENOHUMERAL JOINT)

BALL AND SOCKET 

The most mobile joint in the body

stable?

it would be extremely unstable but,

how about with all these ligaments?

humeral head+glenoid cavity of scapula don't quite fit together :(

but thanks to fibrocart glenoid labrum.

they fit like a dream 

articular surfaces covered by hyaline cart as opposed to fibrocart.

WHY?

(mobility)

Three axes

flex-extend 

abduct-adduct

rotation (medial-lateral)

circumduction

Indicate bony attachments of major ligaments which help maintain stability

ie. somethings gotto stop these joints from moving everywhere:

predict the bony attachments from the names...

Shoulder:

Glenohumeral ligaments - anteriorly

coracohumeral ligament - superiorly

Acromioclavicular:

coracoclavicular ligament (major stability lig)

coracoachromial ligament (avoids humerus dislocation)

Sternoclavicular:

sternoclavicular ligament (keeps everything together)

costoclavicular lig (costo:rib first rib-clavicle)

Indicate sites where major nerves are directly related to humerus:

Radial nerve- passes through the radial groove of humerus

Brachial Plexus?