shoulder girdle Flashcards
How many bones are there in the shoulder girdle (joint)?
3
What type of bone is each individual one?
Humerus – long, Scapula – flat, clavicle – long
What type of joint is the shoulder joint?
Synovial ball and socket
How many, and what types of movement occur at the shoulder joint?
5 types of bone include: Long, short, flat, irregular and sesamoid
HumerusAnatomy(L Arm, Anterior view)
humeral head
greater tuberosity
lesser tuberosity
anatomical neck
surgical neck
deltoid tuberosity
medial epicondyle
lateral epicondyle
capitulum
trochlea
what is a clavicle
Extends and articulates from manubrium of sternum and acromion of the scapula
Three key functions:
- Attaches the upper limb to the trunk as part of the shoulder/pectoral girdle
- Protects the underlying neurovascular structures supplying the upper limb
- Transmits force from upper limb to axial skeleton
when does the clavicle ossify
Differs from other long bones in two ways: 1) it has no medullary cavity and 2) it is ossified in membrane (Dean and West 1991)
Most commonly fractured bone in the body?
“S- shaped”
Flattened, concave lateral element
Thickened, convex medial two-thirds
Ball and socket joint
Head of the humerus articulates with the glenoid cavity of the scapula
Articular surfaces covered in articular hyaline cartilage
Fibrous capsule forms a loose ‘sleeve’ around joint which allows movement
- Attached to the ‘rim’ of the glenoid cavity and laterally to the anatomical neck of humerus
Ball and socket joint
Hyaline cartilage is atype of connective tissue
Synovial membrane lines the fibrous capsule, which secretes synovial fluid and lubricates joint.
Encloses the tendon of the long head of biceps.
Bursae preventing friction during movement.
Fluid-filled bursa between joint and subscapularis muscle (subscapular bursa)
Fluid-filled bursa between the joint and acromion process (subacromial bursa).
Glenoid Labrum deepens the ‘socket’, increasing surface of the joint.
Ossification centres
Approximate age guess – 1.5-2.5 years two ossification centres seen, no lesser tubercle to be seen, very small.
Proximal Humerus Ossification
Primary or secondary centres?
What ages do the following begin ossification?
Head
Greater Tuberosity
Lesser Tuberosity
Tuberosities fuse to form a single epiphysis
Fuse at shaft
Primary will be the core part of the bone, for example the shaft of the humerus will be the primary ossification.
Secondary centres will be part of the active process of bone growth
Proximal Humerus Ossification
Humerus - 8th intrauterine week
Secondary centre ossification ages:
Head- 6 months
Greater Tuberosity- 1-2 years
Lesser Tuberosity- 4-5 years
Tuberosities fuse – coalesce at 6-7 years and fuse to humeral head 7-13 years
Fuse at shaft- 18-20 years or 14-17 in girls & 16-18 in boys
(Gunn, 2017)
Clavicle Ossification
First bone to ossify, last to complete union (Hill, 2020)
Primary Centres- Intramembranous
Two in shaft at 5th week of intrauterine life- medial and lateral
Fuse to form one centre in first year (~45 days)
Secondary Centre- Endochondral
Site appears at sternal end aged 18-20
Fuses with the shaft age 18-25
Scapula Ossification
Primary Centre
Body (towards glenoid cavity)- 8th intrauterine week
Secondary Centres- 7 centres
Coracoid Process (2 centres) appears are:
Lateral – appears at 1yr fuses with body at 15 yrs
Medial - appears at 17yr fuses with body at 25 yrs
Acromion process, 2-3 centres appear at 14-20 (puberty)
Inferior angle, 14-20 years (puberty)
Medial border, 14-20 years (puberty)
Glenoid Cavity, 10-11 years (varies)
All should fuse by age 20-25
Clavicle- Muscular Attachment
Medial 2/3
Origin of Sternocleidomastoid muscle (in neck)- head of clavicle/manubrium. Flexes neck and rotates
Pectoralis Major- flexion, adduction and internal rotation of shoulder joint
Subclavius- depresses shoulder
Costoclavicular ligament
Lateral 1/3
Trapezius- Movement of scapula and neck
Deltoid- flexion, internal rotation and abduction of arm
Coracoclavicular ligament
Muscular Attachments
17 muscles in total attached to the scapula
11 originate from the scapula
Including the 4 rotator cuff muscles – what are they?
6 insert on the scapula
Attachment Sites
Deltoid Tuberosity
- Deltoid Muscle
Lesser Tuberosity
- Tendon of the subscapularis
Greater Tuberosity
- Supraspinatus tendon
- Infraspinatus tendon
- Teres Minor Tendon
Rotator Cuff
4 tendons connect the deepest layer of muscles that rotator cuff muscles to the humerus before these muscles attach to the upper end of the humerus they join together to form a single tendon
these rotoar cuff muscles help raise arm from the side and rotate the shoulder in many ways
Supraspinatus
Responsible for abduction of shoulder
Innervated by suprascapular nerve
Infraspinatus
Responsible for lateral rotation of shoulder
Innervated by suprascapular nerve
Teres minor
Lateral rotation
Innervated by axillary nerve
Subscapularis
Adduction and medial rotation
Innervated by subscapular nerve
The tendons of the muscles, together called the rotator cuff, encircle the joint except inferiorly.
These muscles work together to keep the keep the head of the humerus in the glenoid cavity - socket
Blood supply
Multiple osteochonromas (known as diaphyseal aclasia) is a rare autosomal disorder characterised by multiple bone exostosis mainly affecting the long bones with resultant deformities. It also involves the ribs and scapula. There is a 5% increase in the risk of malignancy in the cartilaginous cap (chondrosarcoma).
Arterial Supply
Scapula Anastomosis
Branches of the subscapular artery e.g. circumflex scapular artery
Suprascapular Artery
Dorsal Scapular artery
Clavicle Vascular Supply
The clavicle is supplied by a nutrient branch of the suprascapular artery
This is one of the branches of the thyrocervical trunk