Upper Limb

Question 1

What joints and bones male up the pectoral girdle?

Answer 1

• Pectoral girdle is made up of two bones – scapular and clavicle
• Joints: sternoclavicular joint the rest of the attachment ot the axial skeleton is purely muscular

Question 2

What muscles insert into the pectoral girdle?

Answer 2

Muscular attachments are either:
oDirect: trunk to clavicle or scapula
Include the following: pectoralis minor, subclavius, trapezius, rhomboids, levator scapulae, serratus anterior
oIndirect: trunk to humerus – move pectoral girdle by means of moving humerus
Include: pectroalis major and latissimus girdle (collectively “great msucles of axillary folds”)

Question 3

Origins and insertions of the pectoralis major and nervous innervation

Answer 3

Origins: 2 heads- the clavicular head and sternocostal head

• the clavicular head originate from the medial half of anterior clavicle  fibres run horizontal in a groove of manubrial part of the muscle attach by the anterior lamina to the lateral lip of the intertubercular sulcus and anterior lip of the deltoid tuberosity
• sternocostal - arise from the manubrium, body of sternum and upper part of teh aponeurosis of external oblique and rectus abdominus + slips from the upper 6 ribs

Insertions: trilaminar tendon:

• clavicular head insert in anterior lamina at lateral lip of the intertubercular groove and anterior lip of the deltoid tuberosity
• manubrial fibres - insert as the intermediate lamina into the lateral lip of the intertubercular groove deep to the clavicular fibres and upper part of the deltoid tuberosity
• sternocostal - transverse up and insert as the posterior lamina

Nervous: medial and lateral pectoral nerves (o Only muscle supplied by all five segments of brachial plexus )

Question 4

pectoralis Minor: origins, insertions, relations and nervous supply

Answer 4

• Origins: triangular muscles arise from the bony parts 3rd, 4th, 5th ribs under pec major (pec major arises more medial from the cartilages)
• Insertion: short thick tendon into the medial border on upper surface of coracoid process (tip occupied by coracobrachialis and biceps)
• relations: Landmark for axillary artery and brachial plexus cords
• Nerves: both pectoral nerves

Question 5

Subclavius: origins, insertions, nervous supply and action

Answer 5

• Origin: costochondral junction of first rib
• Insertion: subclavian groove on clavicle
• Enclosed by the clavipectoral fascia at its attachment
• Nerve: nerve to subclavius (C5-C6), which runs down onto the posterior surface of muscle to enter it
• Action: stabilises clavicle and prevents fractured clavicle from damaging subclavian vein