Anatomy study note · Upper limb

Deltoid

The thick triangular muscle that gives the shoulder its rounded contour. It is the main abductor of the arm.

Key points

• Lateral clavicle + acromion + spine → deltoid tuberosity.
• Axillary nerve (C5, 6).
• Main abductor (15–90°); anterior = flexion, posterior = extension.
• Axillary nerve palsy: flat shoulder + numb lower deltoid skin.
• Limb muscles: in situ from limb-bud mesenchyme.
• Upper limb bud C4–T2; lower limb bud L2–S2.
• Skeletal muscle: multinucleated, peripheral nuclei, striated.
• Epimysium → perimysium → endomysium.

The full note in the atlas also covers

Origin · Insertion · Action · Nerve supply · Histology · Development · Clinical notes

Sign in free to see it on the 3D model, read the full note and practise questions on it.

Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 3, PDF pp. 303, 350
• Inderbir Singh’s Human Embryology, ch. 7, PDF p. 109; ch. 10, PDF pp. 142–145
• BRS Cell Biology & Histology, 7th ed., ch. 8, PDF pp. 135–144

More from the upper limb

• Dorsal scapular nerve
• Elbow joint
• Extensor carpi radialis brevis
• Extensor carpi radialis longus
• Extensor carpi ulnaris
• Extensor digiti minimi
• Extensor digitorum
• Extensor indicis
• Extensor pollicis brevis
• Extensor pollicis longus
• Extensor retinaculum of the wrist
• Flexor carpi radialis

Privacy policy · Designed by DATXOC LLC.