Pectoral Girdle and Shoulder SDL Flashcards
Describe the lateral 1/3 of the clavicle
Concave
Describe the medial 2/3 of the clavicle
Convex
What does the lateral end of the clavicle articulate with?
Acromion –> AC join
What does the medial end of the clavicle articulate with?
Manubrium of sternum and first costal cartilage –> sternoclavicular joint
How do clavicular fractures usually occur?
Usually occur by a direct blow to the shoulder e.g. during a fall or a car collision
Which part of the clavicle usually fractures?
The middle portion (shaft) of the bone
Where does the scapula lie?
Lies on the back of the rib cage between the second and seventh ribs
Where does the scapula articulate with the humerus?
At the glenoid fossa to form the shoulder (glenohumeral) joint
What is the dorsal surface of the scapula divided into?
Supraspinous and infraspinous by the spine of the scapula
What holds the scapula and clavicle together?
Extremely strong ligaments
What are the movements of the scapula?
• up and down (elevation and depression) • forwards (protraction = reaching the arm out in front, as if to push open a door, or throw a punch) • backwards (retraction = ‘squaring’ the shoulders) over the chest wall.
How does the scapula move so the arm can be lifted above the head?
The scapula can move so that the inferior angle can be moved laterally and cranially from the anatomical position. This movement brings the face of the glenoid cavity upwards and allows the arm to be lifted above the head
Where are muscles the move the scapula attached to?
The pectoral girdle, trunk, head and neck
What are the 2 groups of muscles that move the pectoral girdle?
- Dorsal (posterior) group 2. Ventral (anterior) group
What is the dorsal group of muscles comprised of?
2 superficial muscles and 3 deep muscles Superficial: trapezius, lat dorsi Deep: rhomboid major, rhomboid minor, levator scapulae
Diagram of humerus
Palpating scapula on person
Label the muscles
- Trapezius
- Lat dorsi
- Rhom minor
- Rhom major
Origin and insertion of the trapezius?
Origin:
- Superior fibres: superior nuchal line, external occipital protuberence (lower part of skull)
- Middle fibres: nuchal ligament, spinous processes of C1-C6 and C7-T3
- Inferior fibres: spinous processes of T4-T12
Insertion:
- Superior fibres: clavicle
- Middle fibres: acromion and spine of scapula
- Inferior fibres: spine of scapula
What is the trapezius innervated by?
Is the only muscle of the upper limb that does not receive its innervation from the brachial plexus.
Motor: accessory nerve (CN XI)
Sensory: ventral rami C3-C4
Movements on scapula of upper fibres alone of trapezius?
Elevates scapula
Movements alone of middle fibres of trapezius on scapula?
Retracts scapula
Movements alone of inferior fibres of trapezius on scapula?
Depresses scapula
Movement on scapula of all fibres of trapezius working together?
Head and neck extension
Where is lat dorsi located?
Sweeps over the lumbar region and lower thorax and converges to a narrow tendon that inserts on the anterior surface of the humerus. Contribues to the posterior wall of the axilla.
Where does the lat dorsi insert?
Inserts on the floor of the intertubercular groove of the humerus
What are the origins of the lat dorsi?
Vertebral part: Spinous process of T7-L5 and the thoracolumbar fascia.
Costal part: origins from the 9th to 12th ribs
Iliac part: iliac crest
Actions of the lat dorsi?
- Extends arm
- Adducts arm
- Medially rotates arm
Innervation of lat dorsi?
Thoracodorsal nerve (C6-C8)
What are the 3 deep dorsal muscles of the pectoral girdle?
- Levator scapulae
- Rhomboid major
- Rhomboid minor
Origin and insertion of levator scapulae?
Origin: transverse processes of C1-C4 (neck)
Inserts: Upper portion of medial border of scapula
Action of levator scapulae?
Elevates scapula towards neck
Origin and insertion of rhomboid major?
Origin: spinous processes of T2-T5
Inserts: Attaches to the medial border of the scapula, between the scapula spine and inferior angle.
Action of rhomboid major?
Retracts and rotates the scapula.
Innervation of levator scapulae?
Dorsal scapular nerve
Innervation of rhomboid major?
Dorsal scapular nerve.
Origin and insertion of rhomboid minor?
Origin: spinous processes of C7-T1 vertebrae
Insertion: Attaches to the medial border of the scapula, at the level of the spine of scapula
Action of rhomboid minor?
Retracts and rotates the scapula.
Innervation of rhomboid minor?
Dorsal scapular nerve.
What muscles are part of the ventral aspect of the pectoral girdle?
- Serratus anterior
- Pec major
- Pec minor
Origin and insertion of pec major?
Origin:
- Sternal part: from anterior surface of sternum, from costal cartilages 1-6/7
- Clavicular part: from anterior surface of medial clavicle
Inserts:
- Lateral lip of intertubercular sulcus of the humerus
Action of pec major?
Adducts upper limb –> fibres contract and pull humerus towards body
Medially rotates the upper limb and draws the scapula anteroinferiorly.
The clavicular head also acts individually to flex the upper limb –> clavicular fibres contract and pull humerus upwards
Innervation of pec major?
Lateral and medial pectoral nerves.
Origin and insertion of serratus anterior?
Origin: Lateral aspects of ribs 1-8/9
Inserts: They attach to the costal surface of the medial border of the scapula.