Deep Muscles of the Thorax,
Anterior Upper Arm, and Abdomen
Stacey Fain & Christina Duncan
Overview of Deep Muscles
Deep Pectoral Region & Axilla
• Pectoralis Minor
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Origin: Corocoid process of scapula.
Insertion: Ribs 2 to 5
Innervation: Medial pectoral nerve (C8, T1)
Action: Protracts scapula; elevates ribs.
• Serratus Anterior
• External Intercostals
• Internal Intercostals
Veins & Arteries of the Axilla
• Main thing to be
preserved from the
axillary region is the
axillary artery and
the brachial plexus.
Almost all nervous
system and vascular
networks for the arm
originate off of these
two structures.
Muscles of the Upper Arm
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Brachialis Muscle
O: Distal half of anterior surface of the
humerus
I: Tuberosity of the ulna and anterior
surface of the coronoid process
A: Powerful flexor of the forearm
N: Musculocutaneous nerve and
sometimes small branch of radial nerve
(C5, C6)
Coracobrachialis Muscle
O: Coracoid process of the scapula
I: Medial surface of humerus near its
middle
A: Flexes and adducts the arm
N: Musculocutaneous nerve (C6, C7)
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Main Blood Supply
• Vasculature
• Axillary Artery
(Becomes Brachial
Artery once past axillary
region)
• Profunda (deep)
brachii artery
• Superior ulnar
collateral artery
• Radial collateral
artery
Innervation of the Upper
(Musculocutaneous Nerve)
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The Abdomen
Abdominal Muscles
•Internal oblique
•O: Lateral 2/3 of inguinal ligament; the middle lip of iliac crest;
the thoracolumbar fascia
•I: Inferior border of lower 3-4 ribs; the linea alba; aponeurosis
fuses with that of the external oblique to help form the rectus
sheath
•A: Compresses abdominal viscera; both muscles: flex the trunk
forward; each muscle: bends the trunk to that side but rotates
the front of the abdomen toward the same side
•N: Lower five thoracic nerves and the first lumbar nerve (T8-L1)
•Transverse abdominis
•O: Lateral third of inguinal ligament and inner lip of iliac crest;
thoracolumbar fascia; inner surface of lower six ribs
•I: Ends in aponeurosis; upper fibers: to line alba, help form
posterior layer of rectus sheath; lower fibers: attach to pubis to
form conjoined tendon
•A: Tenses abdominal wall; compresses abdominal contents
•N: Lower six thoracic and first lumbar nerves (T7-L1)
More Abs!
Rectus Abdominis
– O: 5th 6th 7th Costal Cartlidges,
Costal xiphoid ligaments and
Xiphoid process.
– I: Crest of pubis and pubis
tuberical, front of symphasis
pubis.
– A: Flexes vertebral column,
tenses anterior abdominal wall.
Compresses abdominal
contents.
– Innervations: Lower 7 thoracic
nevers T6-T12.
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Vascular Supply
• Superior Epigastric Artery
• Inferior Epigastric Arteries
• Inferior Epigastric Vein
Superior Epigastric Artery
Inferior Epigastric Artery
Inferior Epigastric Vein
Inferior Epigastric Artery
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