202 Flashcards
The clavicle is the only bony attachment between the upper limb and trunk. Because it is involved with transferring forces from the upper limb to the trunk, it can easily be fractured.
The scapula is part of the shoulder girdle and all girdles plus limbs are part of the appendicular skeleton. The clavicle is the only bone that connects the upper limb to the trunk.
Which part of the clavicle is usually fractured and why
State the grooves and impressions in the inferior part of the clavicle
The clavicle is usually fractured medial to the conoid tubercle because the middle third of the bone is not reinforced with ligaments or muscles.
• The anterosuperior surface of the clavicle is palpable along its lengt
Excellent observation — you’re absolutely right to ask about the subclavian groove and its relation to the middle third of the clavicle!
Let’s break it down:
- Clavicle fracture site:
• The most common site of clavicle fracture is the middle third — around the junction of the medial two-thirds and lateral one-third.
• This area is thin and curved, and it lacks strong muscular or ligamentous support, making it mechanically weaker.
• That’s why fractures often occur just medial to the conoid tubercle (which is on the lateral third). - Subclavian groove:
• Yes, the subclavian groove is located on the inferior surface of the middle third of the clavicle.
• It provides attachment for the subclavius muscle and the clavipectoral fascia.
So why is it still a weak point despite the subclavian groove?
Even though the subclavius muscle attaches there, it’s a small muscle and doesn’t offer the same strong support as the ligaments attached laterally (like the conoid and trapezoid ligaments of the coracoclavicular ligament complex).
In summary:
• The subclavian groove is in the middle third, yes.
• But this middle third is still the weakest structurally, because:
• It’s more slender and curved.
• It lacks the strong ligaments that reinforce the lateral third.
• The subclavius muscle isn’t strong enough to significantly reinforce it.
That’s why fractures usually happen around that region, even though there’s a groove and a muscle attachment there.
They’re the trapezius line, conoid tubercle(lateral 1/3rd along with the trapezius line), subclavian groove(middle 1/3rd), impression for the costoclavicular ligament(medial 1/3rd( (from most lateral to the medial part)
The coracoclavicular (CC) joint is a synovial joint between the clavicle and the coracoid process of the scapula. The costoclavicular (CC) joint is a synovial joint between the clavicle and the first rib
The trapezoid and conoid ligament come together to form the coracoclavicular ligament. The trapezoid ligament and conoid ligament come together to form the:
Coracoclavicular ligament
This is a strong pair of ligaments that connect the clavicle to the coracoid process of the scapula, and they work together to:
• Stabilize the acromioclavicular (AC) joint
• Suspend the scapula and upper limb from the clavicle
Breakdown:
• Trapezoid ligament = more lateral and runs almost horizontally.
• Conoid ligament = more medial and runs more vertically.
Together, they prevent the clavicle from being pulled upward and help maintain shoulder alignment.
So in short:
• Impression near medial end = Costoclavicular ligament
• Conoid tubercle & trapezoid line near lateral end = Coracoclavicular ligament (conoid + trapezoid parts)
Where do the SITS muscles of the rotator cuff insert at, where do they originate from?
The SIT muscles (Supraspinatus, Infraspinatus, and Teres minor) insert on the greater tubercle of the humerus, not originate from it.
Breakdown:
• Supraspinatus inserts on the superior facet of the greater tubercle.
• Infraspinatus inserts on the middle facet.
• Teres minor inserts on the inferior facet.
These muscles originate from the scapula, and their insertion on the greater tubercle helps stabilize the shoulder joint and assist in arm movements.
(They’re part of the rotator cuff, along with subscapularis, which inserts on the lesser tubercle.)
Great! Let’s look at the specific origins of the SIT muscles (Supraspinatus, Infraspinatus, Teres Minor), which are part of the rotator cuff:
- Supraspinatus
• Origin: Supraspinous fossa of the scapula (the shallow depression above the spine of the scapula)
• Insertion: Superior facet of the greater tubercle of the humerus - Infraspinatus
• Origin: Infraspinous fossa of the scapula (the large surface below the spine of the scapula)
• Insertion: Middle facet of the greater tubercle - Teres Minor
• Origin: Lateral border of the scapula, specifically the upper two-thirds of the posterior surface
• Insertion: Inferior facet of the greater tubercle
So:
• All originate from specific parts of the scapula
• All insert on different facets of the greater tubercle
Let me know if you want a quick mnemonic to remember this!
The three most common sites of humeral fracture are
Surgical neck
Midshaft
Supracondylar
Sure! Here are short answer questions that cover everything in the response above:
1. What is the suprascapular notch? 2. Where is the suprascapular notch located? 3. Which ligament bridges the suprascapular notch? 4. What does the suprascapular notch become when bridged by the transverse scapular ligament? 5. What structure passes under the transverse scapular ligament? 6. Which structures usually pass over the transverse scapular ligament? 7. What mnemonic helps remember the relationship of the artery and nerve at the suprascapular notch? 8. What is the name of the foramen formed when the suprascapular notch is bridged by a ligament? 9. If the transverse scapular ligament is absent, what does the area remain as? 10. Is the suprascapular notch the same as the supraclavicular notch? Why or why not?
Let me know if you want the answers filled in too!
Remember that the suprascapular notch is different from the greater scapular notch.
The suprascapular artery, vein and nerve all pass through the greater scapular notch to innervates the supraspinatus and then the infraspinatus muscles but with the suprascapular notch, the nerve passes through it and the vein and artery pass over it or over the ligament.
The glénoïde cavity has supraglenoid and infraglenoid. The long head of the biceps brachii attaches to the supraglenoid and the long head of the triceps brachii attaches to the infraglenoid.
You’re very close — let’s clarify and rephrase it for better understanding:
Correct Concept:
• The suprascapular notch is a notch on the superior border of the scapula, near the base of the coracoid process.
• It is bridged by the transverse scapular ligament (also called the superior transverse scapular ligament).
When the ligament is present:
• It converts the notch into a foramen called the:
• Suprascapular foramen (not “foramen scapular”).
• Through this foramen:
• The suprascapular nerve passes under the ligament (through the foramen).
• The suprascapular artery and vein usually pass over the ligament (not through the foramen).
• Mnemonic: “Army over Navy under” (A=artery, N=nerve)
If the ligament is absent:
• The notch remains a simple suprascapular notch — not called supraclavicular notch (which is a different anatomical structure in the clavicle).
To summarize:
• Ligament present: Suprascapular notch → Suprascapular foramen
• Ligament absent: Remains the suprascapular notch
• Suprascapular nerve goes through the foramen (under the ligament)
Let me know if you want a labeled diagram to visualize this!
Great! Here are the short answer questions with their answers:
1. What is the suprascapular notch? – A notch on the superior border of the scapula. 2. Where is the suprascapular notch located? – Near the base of the coracoid process on the scapula. 3. Which ligament bridges the suprascapular notch? – The transverse scapular ligament (superior transverse scapular ligament). 4. What does the suprascapular notch become when bridged by the transverse scapular ligament? – The suprascapular foramen. 5. What structure passes under the transverse scapular ligament? – The suprascapular nerve. 6. Which structures usually pass over the transverse scapular ligament? – The suprascapular artery and vein. 7. What mnemonic helps remember the relationship of the artery and nerve at the suprascapular notch? – “Army over Navy under” (Artery over, Nerve under the ligament). 8. What is the name of the foramen formed when the suprascapular notch is bridged by a ligament? – Suprascapular foramen. 9. If the transverse scapular ligament is absent, what does the area remain as? – It remains the suprascapular notch. 10. Is the suprascapular notch the same as the supraclavicular notch? Why or why not? – No. The suprascapular notch is on the scapula, while the supraclavicular notch is on the clavicle near the sternum.
The sternoclavicular joint is reinforced by four ligaments
Name them
The acromioclavicuoar joint is reinforced by two ligaments. Name them
Rotator cuff muscles stabilize the glenohumeral joint so it doesn’t have ligaments that reinforce it
The lateral angle not the lateral border of the scapula is modified to form the glénoïd cavity
Sterno: anterior and posterior strernoclavicular ligaments, costoclavicular ligament(this just connects the proximal end of the clavicle to the first rib) ,interclavicular ligament
Acromio: small acromioclaviucoar ligament and big coracoclavicular ligament. and acror and
• a much larger
cacoclavicularligament, which is
not directly related to the join
is an important
strong accessory ligament, providing much of the weight-bearing support for the upper limb on the clavicle and maintaining the position of the clavicle on the acromion-it spans the distance between the coracoid process of the scapula and the inferior surface of the acromial end of the clavicle
Glenohumeral joint
Between Which joints in the elbow joint are involved in the hinge like extension and flexion of the forearm on the arm and between which joints in the elbow joint are invovled in the pronation and supination of the forearm
Extension flexion:
Between the Head of the radius and the capitulum of the humerus and between the Trochlear notch of the ulna and the Trochlear of the humerus
Pronation and supination:
Joint Between the Head of the radius and the radial notch on the ulnar, the proximal radio-ulnar joint
State the three parts of axillary artery and the number of branches each part had
The axillary artery has 3 parts, divided by the pectoralis minor muscle:
Part,Location,Branches
First part,Before (proximal to) pectoralis minor,1 branch → Superior thoracic artery
Second part,Behind (deep to) pectoralis minor,2 branches → Thoracoacromial artery and Lateral thoracic artery
Third part,After (distal to) pectoralis minor,3 branches → Subscapular artery, Anterior circumflex humeral artery, Posterior circumflex humeral artery
Easy way to remember:
• 1st part → 1 branch
• 2nd part → 2 branches
• 3rd part → 3 branches
Mnemonic for branches:
“Screw The Lawyer Save A Patient”
(Superior thoracic, Thoracoacromial, Lateral thoracic, Subscapular, Anterior circumflex humeral, Posterior circumflex humeral)
The 5 Groups of the axillary lymph nodes
The axillary lymph nodes are divided into 5 groups, based on their location around the axillary (armpit) area:
1. Central nodes – Located in the center of the axilla.
2. Pectoral (anterior) nodes – Located along the lower border of the pectoralis major muscle.
3. Subscapular (posterior) nodes – Located along the subscapular artery, near the scapula.
4. Lateral nodes – Located along the humerus, near the axillary vein.
5. Apical nodes – Located at the apex of the axilla, near the clavicle and first rib.
Quick way to remember:
“Please Send Little Packages Away” (For Pectoral, Subscapular, Lateral, Pectoral, Apical)
Note: The axillary nodes are important for draining the upper limb and chest, and they can be affected in conditions like breast cancer.
Would you like a reminder on how to check for lymph node enlargement?
Types of epiphysis
Here’s a clean breakdown for you:
Types of Epiphysis
1. Pressure epiphysis
• Function: Helps in joint movement and bears pressure.
• Example: Head of femur, head of humerus.
2. Traction epiphysis
• Function: Provides attachment for tendons and ligaments; doesn’t take part in joints.
• Example: Greater and lesser trochanters of femur.
3. Atavistic epiphysis
• Function: Represents a bone that was separate during evolution but fused later.
• Example: Coracoid process of scapula.
4. Aberrant epiphysis (sometimes called “accessory”)
• Function: Extra epiphysis not always present; variation.
• Example: Sometimes at the base of the first metacarpal.
Quick way to remember:
“Please Take A Apple” (Pressure, Traction, Atavistic, Aberrant)
Would you also like a super short line on how to tell traction vs pressure epiphysis in exam questions? It’s a fast trick!
What structure passes through the transition areas of the upper limb?
The deep brachial artery gives off what branches?
Which nerves give the cutaneous innervation of the forearm?
By which day would 15 pairs of somites have been formed?
A. 20
B. 24 C. 25 D. 23
The musculocutaneous nerve is found between which muscles?
Which pair of muscles are NOT innervated by the same nerve?
Options given:
1. Teres major
2. Teres minor
3. Supraspinatus
4. Infraspinatus
5. Deltoid
A. 1 and 5 B. 3and4 C. 2and 5 D. ?
A cell releases hormones on receptors of its adjacent cells. This is A. Paracrine
B. Endocrine C. Juxtacrine D. Exocrine
Which is true about the anatomical snuff box
I. Its floor is made up of scaphoid bone
II. The Radial artery is found at the base
III. The extensor pollicis longus is at the medial border
A. I and II
B. I, II and III C. I only
D. I and III
11. Which is medial to the brachial artery in the cubical fossa A. Median nerve
B. Tendon of biceps brachii C. Ulnar nerve
D.?
What structure passes through the transition areas of the upper limb?
Answer: D. Brachial artery
• The brachial artery passes through important transition areas like the cubital fossa.
- The deep brachial artery gives off what branches?
Answer:
• It gives middle collateral artery and radial collateral artery branches.
(They help form the anastomosis around the elbow.)
Which nerves give the cutaneous innervation of the forearm?
Answer:
• Lateral cutaneous nerve of forearm (from musculocutaneous nerve)
• Medial cutaneous nerve of forearm
• Posterior cutaneous nerve of forearm (from radial nerve)
By which day would 15 pairs of somites have been formed?
Answer: D. 23
• Somites start appearing by day 20, and by day 23, about 15 pairs have formed.
The musculocutaneous nerve is found between which muscles?
Answer:
• Biceps brachii and brachialis muscles.
And the brachial plexus is between the scalene muscles
Which pair of muscles are NOT innervated by the same nerve?
Options given:
1. Teres major
2. Teres minor
3. Supraspinatus
4. Infraspinatus
5. Deltoid
Answer:
A. 1 and 5 (Teres major and Deltoid)
• Teres major is innervated by lower subscapular nerve.
• Deltoid is innervated by axillary nerve.
• So they are innervated by different nerves.
A cell releases hormones on receptors of its adjacent cells. This is called:
Answer: A. Paracrine
• Paracrine = affects nearby cells.
• Endocrine = affects distant cells via blood.
• Juxtacrine = direct contact (no diffusion).
Answer: B. I, II and III
Explanation:
• I. Floor is made up of the scaphoid bone — True (and trapezium bone too).
• II. Radial artery found at the base — True (you can feel the pulse there).
• III. Extensor pollicis longus forms the medial border — True.
Quick summary of the anatomical snuff box:
• Borders:
• Medial: Extensor pollicis longus tendon.
• Lateral: Extensor pollicis brevis and abductor pollicis longus tendons.
• Floor: Scaphoid and trapezium bones.
• Contents: Radial artery (pulse felt here).
Want a simple mnemonic to remember the snuff box quickly?
- Answer: A. Median nerve
Explanation:
In the cubital fossa, from lateral to medial, the structures are arranged as:
Tendon of biceps brachii → Brachial artery → Median nerve
So the median nerve lies medial to the brachial artery.
Contents of the cubital fossa
Here’s a detailed and very clear breakdown of the contents of the cubital fossa:
From lateral to medial (easy to remember with the mnemonic “TAN”):
1. T – Tendon of biceps brachii
2. A – Brachial artery
• (and its branches: radial and ulnar arteries start around here)
3. N – Median nerve
Other structures related to it (but not exactly inside):
• Radial nerve (found under the brachioradialis muscle laterally)
• Gives off superficial and deep branches near the fossa
• Median cubital vein (superficial, in the roof — commonly used for venipuncture)
• Basilic vein and cephalic vein (also in the superficial fascia)
Boundaries of the cubital fossa (important for orientation):
• Lateral boundary: Brachioradialis muscle
• Medial boundary: Pronator teres muscle
• Superior boundary (base): Imaginary line between the medial and lateral epicondyles of the humerus
• Roof: Skin, superficial fascia, and bicipital aponeurosis
• Floor: Brachialis and supinator muscles
Quick picture in your mind:
• Deep inside: Tendon - Artery - Nerve (TAN from lateral to medial)
• Roof: veins (especially median cubital vein)
• Floor: muscles (brachialis, supinator)
Would you also like a simple diagram or mnemonic to remember the extra related structures? (It can make it even faster to recall.)
Brachial plexus
State the roots of the brachial plexus.
Which roots come together to form the superior or upper trunk?
Which form the middle trunk?(remember middle is in between up and down so the trunk is middle not medial. The cord is medial)
Which form the posterior trunk?
The dorsal scapular nerve and phrenic nerve arrives from what root and innervates what muscle?
The long thoracic nerve comes from what roots and innervates what muscle?
The suprascapular nerve and subclavius nerve arises from what trunk?
Question 1:
The cords of the brachial plexus are named based on their relationship to which anatomical structure?
A. Subclavian artery
B. Axillary artery
C. Brachial artery
D. Scapular artery
Question 2:
Which of the following is NOT true about the formation of the cords in the brachial plexus?
A. The lateral cord is formed by the anterior divisions of the upper and middle trunks.
B. The posterior cord is formed by the posterior divisions of all three trunks.
C. The medial cord is formed by the anterior division of the lower trunk.
D. The lateral cord is formed by the anterior division of the upper trunk only.
Question 3:
Which of the following cords of the brachial plexus is responsible for the formation of the ulnar nerve?
A. Lateral cord
B. Medial cord
C. Posterior cord
D. Upper trunk
What nerves arise from the middle cord?
What nerves arise from the medial cord?
The lateral pectoral nerve arises from what cord and innervates what muscle?
Medial cord gives rise to what two terminal nerves?
Posterior cord gives rise to what terminal nerve?
Lateral cord gives rise to what two terminal nerves?
Median nerve arises from what two cords?
Alright — I’ll answer each part clearly and step-by-step for you:
- State the roots of the brachial plexus:
• C5, C6, C7, C8, and T1 - Which roots come together to form the superior (upper) trunk?
• C5 and C6 roots join to form the superior trunk. - Which forms the middle trunk?
• C7 root continues alone to form the middle trunk.
(Good note you made: “middle” means between upper and lower, not “medial.”)
- Which form the inferior (lower) trunk?
• C8 and T1 roots join to form the inferior trunk. - The dorsal scapular nerve and phrenic nerve arise from what root and innervate what muscles?
• Dorsal scapular nerve
• Arises from: C5 root
• Innervates: Rhomboid major and rhomboid minor muscles (and sometimes levator scapulae)
• Phrenic nerve
• Arises mainly from: C3, C4, C5 roots (“C3, 4, 5 keep the diaphragm alive”)
• Innervates: Diaphragm
(For brachial plexus context, it’s mainly noted that C5 contributes.)
- The long thoracic nerve comes from what roots and innervates what muscle?
• Arises from: C5, C6, and C7 roots
• Innervates: Serratus anterior muscle
(Injury causes winged scapula.) - The suprascapular nerve and subclavius nerve arise from what trunk?
• Both arise from the superior trunk (formed by C5 and C6).
• Suprascapular nerve → Innervates supraspinatus and infraspinatus muscles
• Nerve to subclavius → Innervates subclavius muscle
Would you also like a few MCQs based on this to quickly test yourself? (It’ll be short and sharp!)
Here are the MCQs with the answers included:
Question 1:
The cords of the brachial plexus are named based on their relationship to which anatomical structure?
A. Subclavian artery
B. Axillary artery
C. Brachial artery
D. Scapular artery
Answer:
B. Axillary artery
Explanation:
The cords of the brachial plexus (lateral, posterior, and medial) are named based on their position relative to the axillary artery.
Question 2:
Which of the following is NOT true about the formation of the cords in the brachial plexus?
A. The lateral cord is formed by the anterior divisions of the upper and middle trunks.
B. The posterior cord is formed by the posterior divisions of all three trunks.
C. The medial cord is formed by the anterior division of the lower trunk.
D. The lateral cord is formed by the anterior division of the upper trunk only.
Answer:
D. The lateral cord is formed by the anterior division of the upper trunk only.
Explanation:
The lateral cord is actually formed by the anterior divisions of both the upper and middle trunks, not just the upper trunk.
Question 3:
Which of the following cords of the brachial plexus is responsible for the formation of the ulnar nerve?
A. Lateral cord
B. Medial cord
C. Posterior cord
D. Upper trunk
Answer:
B. Medial cord
Explanation:
The ulnar nerve is primarily formed from the medial cord of the brachial plexus.
Let me know if you need more questions or further clarification!
The nerves from the posterior cord are the superior subscapular,thoracodorsal(medial subscapular nerve),inferior subscapular nerve,axillary nerve (sort of)
The nerves from The median cord are the medial pectoral, medial cutaneous nerve of the arm, medial cutaneous nerve of the forearm.
The lateral pectoral nerve arises from the lateral cord and innervates pectoralis major.
Posterior gives rise to the radial nerve
Lateral gives rise to median and musculocutaneous nerve
Median nerve arises from the lateral and medial cords.
Medial cord gives rise to median and ulnar nerves.
The axilla is what shape and has how many borders, an inlet and a floor?
State the names of each border and what is in the inlet and floor
It is pyramidal shaped.
Has 4 borders
Anterior
Posterior
Medial
Lateral
The inlet is made up of the 1.lateral margin of the first rib(this rib is flat but superolateral while the others are inferiolateral)
2.posterior border of the clavicle
3. Superior margin of the scapula extending to the coracoid process
Subclavian artery is called axillary artery once it enters the axilla
The floor is dome shape. The lateral side of the floor becomes the outlet. The floor made up of the anterior and posterior axillary fold. Anterior Axillary Fold:
• Made up of: The anterior axillary fold is primarily formed by the pectoralis major muscle and its overlying skin and fascia.
Posterior Axillary Fold:
• Made up of: The posterior axillary fold is formed by the latissimus dorsi and teres major muscles and their associated skin and fascia.
1.The subscapularis, teres major, latissimus dorsi, long head of the triceps brachii form which wall of the axilla?
2.The upper part of the thoracic wall or rib cage and the serratus anterior muscle form what wall of the axilla?
3.The pectoralis major and minor, subclavius muscle and clavipectoral fascia form what wall of the axilla?
4.The intertubercular sulcus or groove of the humerus forms which wall of the axilla?
1.posterior
2.medial
3.anterior
4. The lateral wall of the axilla is primarily formed by the humerus (specifically, the intertubercular groove or sulcus or bicipital groove), along with the muscles surrounding it, including:
• Coracobrachialis muscle
• Biceps brachii muscle
Good question!
The long head of the triceps brachii forms part of the posterior wall (not just the border) of the axilla because of its origin and position:
• The long head originates from the infraglenoid tubercle of the scapula — that’s very close to the shoulder joint.
• From there, it runs downward along the back of the arm, but near the armpit (axilla) it lies next to other posterior muscles like:
• Subscapularis (upper part),
• Teres major (middle part),
• and itself (long head of triceps, lower part).
So, in the lower part of the posterior axillary wall, the long head of triceps helps complete the muscle boundary, preventing the space from being “empty” at the bottom.
Simple way to think of it:
• Upper posterior wall = subscapularis
• Middle posterior wall = teres major and latissimus dorsi
• Lower posterior wall = long head of triceps brachii
Would you also like a simple diagram to visualize it better?
I’m glad you found the information helpful! Here are the answers to the MCQs, along with the explanations:
Question 8:
Answer: A. Internal thoracic artery
Explanation: The internal thoracic artery is a branch of the subclavian artery, and it supplies the anterior chest wall and the breasts.
Question 9:
Answer: B. Supplies the brainstem and posterior part of the brain
Explanation: The vertebral artery, which is a branch of the subclavian artery, supplies the brainstem, cerebellum, and the posterior part of the brain.
Question 10:
Answer: C. Subscapular artery
Explanation: The subscapular artery is a branch of the axillary artery and supplies muscles of the back and shoulder.
Question 11:
Answer: B. Axillary artery
Explanation: The axillary artery continues through the axilla and is considered the continuation of the subclavian artery once it passes the first rib.
Question 12:
Answer: D. Inferior border of the teres major muscle
Explanation: The subclavian artery becomes the brachial artery at the level of the inferior border of the teres major muscle, which marks the transition from the axilla to the arm.
Question 13:
Answer: A. At the cubital fossa
Explanation: The brachial artery bifurcates into the radial and ulnar arteries at the cubital fossa, which is located at the elbow.
Question 14:
Answer: A. First rib and clavicle
Explanation: The subclavian artery passes between the first rib and clavicle to enter the axilla, where it becomes the axillary artery.
Question 15:
Answer: C. Three
Explanation: The axillary artery is divided into three parts based on its relationship to the pectoralis minor muscle:
1. First part: Between the subclavian artery and the medial border of the pectoralis minor.
2. Second part: Behind the pectoralis minor.
3. Third part: From the lateral border of the pectoralis minor to the inferior border of the teres major muscle.
In-depth Knowledge on Transitions of the Subclavian Artery:
1. Subclavian artery:
• Origin: The subclavian artery originates from different sources on either side of the body. On the right side, it arises from the brachiocephalic trunk, while on the left side, it arises directly from the aortic arch.
• Course: It passes laterally across the neck, running behind the scalene muscles, and gives off several important branches (e.g., vertebral artery, internal thoracic artery, thyrocervical trunk).
2. Transition to the Axillary Artery:
• As the subclavian artery passes over the first rib, it becomes the axillary artery. The point at which it changes is defined as the level of the first rib, and the artery is now known as the axillary artery.
• The axillary artery is divided into three parts based on its relationship to the pectoralis minor muscle:
• First part: From the lateral border of the first rib to the medial border of the pectoralis minor muscle.
• Second part: Behind the pectoralis minor.
• Third part: From the lateral border of the pectoralis minor to the inferior border of the teres major muscle.
3. Transition to the Brachial Artery:
• As the axillary artery passes the inferior border of the teres major muscle, it becomes the brachial artery.
• The brachial artery travels down the arm and gives off important branches (e.g., deep brachial artery for the muscles of the arm), and at the elbow, it bifurcates into the radial and ulnar arteries.
4. Main Branches of the Subclavian, Axillary, and Brachial Arteries:
• The subclavian artery gives rise to several branches, including the vertebral artery (which supplies the brain), the internal thoracic artery (which supplies the anterior chest wall), and the thyrocervical trunk (which supplies the thyroid gland and neck).
• The axillary artery gives rise to the subscapular artery, brachial artery, and circumflex arteries.
• The brachial artery gives rise to the radial and ulnar arteries, which supply the forearm and hand.
Let me know if you’d like more detailed explanations or additional MCQs!
From the anterior wall, the pectoralis major has 2 heads. Name them.
State their origins and insertion.
State their actions as well.
State their innervations
The clavicular head
Sternocostal head
Clavicular head: anterior border of the medial half of the clavicle
Sternal head: costal cartilages of the first upper 7-8 ribs. It’s the costal cartilages that do the articulation with the sternum.
The two heads converge to form a tendon that inserts at the lateral lip of the intertubercular sulcus.
The sternal head assists in extension. Both heads do medial rotation of the arm.
They both adduct the arm.
Clavicular head does flexion of the arm at the shoulder joint.
Innervated by the medial and lateral pectoral nerves.
on the arm’s starting position.
• From anatomical position (arm at side), the clavicular head flexes.
• If the arm is already flexed (e.g., overhead), the sternal head extends it down.
You’re right to notice that — let’s go carefully:
When your arm is lifted straight up (over your head) and you contract the sternal head of pectoralis major, it pulls your arm downward and slightly inward toward your chest — like you’re trying to pull something down and hug it into your body.
It’s not that the arm literally touches your sternum — it’s that the movement is toward the midline (adduction and extension back to your side or even slightly in front of you if the arm was very high).
Summary:
• If arm is lifted, sternal head helps extend and adduct the arm.
• It brings the arm closer to the front and midline.
Tip: Imagine doing a wide pull-up motion — your arms pull down toward your chest.
Would you like a mini drawing or movement tip to visualize it better? It’s very common to get confused here.
Sure! Here’s a simple breakdown of the axillary artery parts and branches:
The axillary artery is divided into 3 parts based on the pectoralis minor muscle:
1. First part — Above (proximal to) pectoralis minor
• Branch:
• Superior thoracic artery
2. Second part — Behind (posterior to) pectoralis minor
• Branches:
• Thoracoacromial artery (which itself has 4 small branches: clavicular, acromial, deltoid, pectoral)
• Lateral thoracic artery
3. Third part — Below (distal to) pectoralis minor
• Branches:
• Subscapular artery (divides into circumflex scapular and thoracodorsal arteries)
• Anterior circumflex humeral artery
• Posterior circumflex humeral artery
Easy way to remember:
• 1 branch from the first part
• 2 branches from the second part
• 3 branches from the third part
Would you like a quick mnemonic to memorize them too?
Pectoralis minor :
Origin
Insertion
Innervation
Action
Origin: anterior surfaces of rib 3-5(not the costal cartilages)
Insertion: coracoid process
Innervation: medial pectoral nerve
Action: scapular movement anteriorly and inferiorly
Subclavius muscle:
Origin
Insertion
Innervation
Action
What are the borders of the clavipectoral groove?
What three structures pierce the clavipectoral fascia?
What adds up to the borders to form the clavipectoral triangle?
Remember that anything in front is likely to be the anterior wall of the axilla( so pec major and minor, subclavius and clavipectoral fascia)
Origin: rib 1 at Costcochondral junction
Insertion: subclavian groove of the clavicle
Innervation: subclavian nerve
Action: moves or depresses the clavicle inferiorly and stabilizes clavicle
Borders: medial aspect of the triangle - lateral border of clavicular head of the pectoralis major
Lateral aspect of the triangle- Medial border of the anterior part of the deltoid muscle
The base-The clavicle adds up to form the clavipectoral triangle
So just the medial and lateral part will be groove.
Structures that pierce the fascia: lateral pectoral nerve, cephalic vein (which passes through the clavipectoral groove or travels in the deltopectoral groove and pierces the fascia to drain into the axillary vein), pectoral branch of the thoracoacromial artery.
Note: This triangle is an important anatomical landmark used in procedures like central venous access or pacemaker insertion.
