Muscles of the upper arm - groups, attachments, action, and nerve supply.

muscles of the upper arm

- located between shoulder joint & elbow joint

- split into 2 compartments: anterior & posterior

anterior compartment of the muscles of upper arm

- "BBC"

- arterial supply

- biceps brachii, brachialis, coracobrachialis

- arterial supply: muscular branches of brachial artery

biceps brachii

- two-headed muscle

- majority of muscle is mass located anteriorly to humerus (not attachment to bone)

- enters forearm, connective sheet is given off: "bicipital aponeurosis"

- roof of cubital fossa + blends with deep fascia of anterior forearm

biceps brachii attachments

- LONG HEAD: supraglenoid tubercle

- SHORT HEAD: coracoid process

- BOTH HEADS: insert distally into radial tuberosity + fascia of forearm via bicipital aponeurosis

biceps brachii actions

supination of forearm: flexes arm at elbow + shoulder

biceps brachii nerve supply

- musculocutaneous nerve

(- bicep tendon reflex tests spinal cord segment C6)

coracobrachialis

deep to biceps brachii

coracobrachialis attachments

- coracoid process of scapula

- passes through axilla, attaches to medial side of humeral shaft (level of deltoid tubercle)

coracobrachialis actions

- flexion of arm at shoulder

- weak adduction

coracobrachialis nerve supply

musculocutaneous nerve

brachialis

- deep to biceps brachii

- found more distally than other muscles of arm

- floor of cubital fossa

brachialis attachments

- medial + lateral surfaces of humeral shaft

- inserts into ulnar tuberosity - distal to elbow joint

brachialis actions

flexion at elbow

brachialis nerve supply

- musculocutaneous nerve

- contributions from radial nerve

posterior compartment of the muscles of the upper arm

- name of muscle

- arterial supply

- triceps brachii

- arterial supply: deep brachial artery

triceps brachii

- 3 heads, medial head is deeper than other 2

- arterial supply: deep brachial artery

triceps brachii attachments

- LONG HEAD: infraglenoid tubercle

- LATERAL HEAD: humerus - superior to radial groove

- MEDIAL HEAD: humerus (inferior to radial groove)

- Distally: heads converge and insert onto olecranon of ulna

triceps brachii actions

extension of arm at elbow

triceps brachii nerve supply

- radial nerve (for some, may be innervated by axillary nerve)

(- tap on triceps tendon: tests for C7)