Main structures of the upper limb (the arm) Flashcards
To be able to identify the structures of the upper limb.
what is the clavicle and where are the landmarks on it?
The clavicle is a long bone that connects the pectoral girdle to the thorax anteriorally via the sternum. There are two ends of the clavicle, the medial or sternal end that meets with the sternum and the lateral or acromion end that meets with the shoulder. The clavicle is divided into three parts, there is the medial two thirds and then the lateral one third that has a downward dip in it.
where is the clavicle most likely to fracture?
between the medial two thirds and the lateral one third.
where does the costoclavicular ligament attach onto the clavicle?
Costoclavicular ligament is a ligament that connects the sternal end of the clavicle to the sternal end of the first rib. It runs on an oblique angle.
where is the coracoclavicular ligament and what are the two smaller ligaments that it is comprised of?
The coracoclavicular ligament is a ligament that connects the clavicle to the coracoid process of the scapula (near acromion). This ligament is made up of the trapezoid (trapezoid shape) and conoid (cone shaped) ligaments.
Name the three borders of the scapula.
The medial border lies closest and parallel to the vertebral column. The superior border runs paralell to the clavicle and the coracoid process comes off this. Then the lateral border runs on an oblique angle inwards towards the medial border.
What are the key bony landmarks on the scapula?
There is a long bony projection that cuts accross the scapula diagonally called the spine of the scapula. This spine has a bony projection off the lateral end that sticks out- this is called the acromion process. Directly opposite the acromion process there is the coracoid process. Below the acromion and coracoid processes lies a smooth rounded articular surface called the glenoid fossa.
where is the coracoacromial ligament with respect to the scapula?
it is a ligament between the coracoid process and the acromion process.
where is the coracohumeral ligament with respect to the scapula?
It is found between the coracoid process and the humerus.
where is the superior transverse scapular ligament?
It is a small ligament located within the suprascapular notch formed between the superior border of the scapula and the coracoid process next to it.
what are the key bony landmarks of the humerus?
The humerus has its head (1/3rd of a sphere), that articulates with the glenoid fossa on the scapula. Then, there is the anatomical neck, which is the border between the smooth articular head surface and the rest of the humerus. The surgical neck of the humerus is an imaginary line where the bone starts to narrow into the shaft. The shaft of the humerus is thinnest part of the bone in the middle.
The distal end of the humerus is split into either the medial or lateral condyles. Within these bigger condyles are the bony projections the medial and lateral epicondyles that are the common origins for the forearm muscles. Between the epicondyles is the articular surface for the radius and ulna. They are the capitulum (looks like a butt cheek)
on the lateral side and the trochlea ( looks like a sideways horse’s hoove) on the medial side.
There are 2 fossa directly above the capitulum and the trochlea. The radial fossa is directly above the capitulum, and the coronoid fossa above the trochlea.
Where are the sites of muscle attachment or fossa on the humerus?
At the proximal end of the humerus (closer to the shoulder), there are two tubercles on the humeral head. The larger is called the greater tuberosity and the smaller the lesser tuberosity. Between these two tubercles is a groove where the tendon of the long head of the biceps brachii lives, called the bicipital or intertubercular groove. In the humeral shaft, there is a third tuberosity called the deltoid tuberosity because this bump is where the deltoid attaches to the humerus.
At the distal end of the humerus are the three important fossa, the olecranon fossa forms one large hole on the posterior side of the humerus. Then the other two are on the anterior side of the humerus being the radial fossa laterally and the coronoid fossa medially.
what are the bony landmarks of the ulna?
The ulna bone lines medially within the forearm and at the proximal end has been modified to sit into the elbow. The olecranon is the hooked bony process that actually locks into the olecranon fossa posteriorally during elbow extension. Elbow extension also requires the trochlea notch on the ulnar to lock into the gap inbetween the coronoid and radial fossa anteriorally. On the lateral side of the anterior ulna, we see there is a radial notch, where the head of the radius articulates with the side of the ulna.
At the distal end of the ulna, we see the head which is flat and cylindrical. This ulnar head does not make contact with the carpal bones of the wrist. The styloid process is a small hook like the trochlea notch but distally.
What are the bony landmarks of the radius?
Within the forearm, the radius lies along the radial side. The proximal end of the radius is where the radial head articulates with the radial notch. The radial head though has a radial neck below that is a 360 degree articular surface to allow pronation and supination.
Then there is the radial tuberosity for tendon and muscle attachment (to be covered later). There is the radial shaft where the interosseous membrane attaches.
The largest part of the radius is the distal end, where it makes contact with the carpal bones of the wrist. On the lateral side of the distal end there is another styloid process (its like a hook on the side of radius). Then ther e is the carpal articular surface where the radius articulates with the carpal bones.
What are the carpal bones?
They are a group of 8 small bones that form the wrist.
Name the 8 carpal bones in both the proximal and distal layers.
Proximal row: Scaphoid,Lunate,Triquetral, Pisiform,
Distal row: Trapezium, trapezoid, capitate, harnate.
Acronym: SLTPTTCH
which of the carpal bones articulate with the radius’s carpal articular surface laterally?
The scaphoid and lunate bones articulate with the radius.
what is the midcarpal joint?
It is the physiological joint between the proximal and distal row of carpal bones.
What is the flexor retinaculum?
Also known as the transverse carpal ligament. It is the name of the fascial sheath that covers the carpal bones accross the wrist. It protects the flexor muscle tendons of the digits as they enter the hand from the forearm. The flexor retinaculum forms the roof of the carpal tunnel.
what are the sites of attachment for the flexor retinaculum?
The flexor retinaculum attaches to the tubercle on the scaphoid, the crest of the trapezium, the pisiform bone and the hook of hamate.
what are the metacarpals?
These are the long bones of the palm. There are 5 for each digit.
what are the phalanges and what are their 3 sub groups?
The phalanges are the bones of the fingers. There are the proximal, middle and distal phalanges.
where is the sternoclavicular joint found?
This joint is found in the pectoral girdle (shoulder),and is where the sternum and clavicle articulate.
which ligaments sorround and support the sternoclavicular joint?
The anterior and posterior sternoclavicular ligaments and the costoclavicular ligament.
the sternoclavicular joint contains what structure inside for articulation?
There is an articular disc, that splits the cavity into two.
where is the acromioclavicular joint found?
It is found between the acromion and the clavicle.
This joint is very prone to fractures in sports people. There is a grading system according to the severity of the tear, from grade 1 being slight tear to grade 3 being a complete split and seperation of the acromion from the clavicle.
which ligaments support the acromioclavicular joint?
The joint is supported by the superior and inferior acromioclavicular ligaments and the coracoclvicular ligaments.
What are the articular surfaces that make up the shoulder joint?
The humeral head articulates with the glenoid fossa.
what are the main ligaments that sorround the shoulder joint?
Glenohumeral ligaments, coracohumeral ligaments, coracoacromial ligament and the transverse humeral ligament (small ligament over the biciptal groove to keep head of biceps inside).
what are the special articular structures found within the shoulder joint?
The shoulder joint has a labrum, which is a lip extension which is found around the rim of the glenoid fossa. This acts to deepen the socket and provide stability.
It also has a subacromial bursa, that prevents friction between the humeral head and the acromion process.
The tendon of the long head of the biceps which passes through the bicipital groove also inserts into this shoulder joint.
What is the name of the group of muscles that stabilise and insert into the shoulder joint?
Rotator cuff muscles
Where is the muscle pectoralis major found and what is its action?
Pectoralis major originates from the medial, anterior part of the clavicle and along the sternum. It inserts onto the bicipital groove,which is the smooth, flat surface immediately below the turbercle. It functions as a prime mover muscle thatadducts and medially rotates the humerus.
where is the muscle pectoralis minor and what is its action?
The pectoralis minor is a deep muscle, located underneath the pectoralis major. It originates from the T3-T5 ribs and inserts onto the corocoid process.
It works to pull the top of the scapula down and forward onto the thorax, so that the inferior angle of the scapula sticks out posteriorally.
where is the muscle serratus anterior and what is its main action?
The serratus anterior muscle is really a large cluster of muscles that originate from ribs 1-9, and all insert onto various points along the medial border of the scapula.
Together, these muscles work to pull the scapula forward onto the thorax during arm elevation.
where is the trapezius muscle and what is its main action?
The trapezius muscle is another large superficial muscle that originates from the top of the neck all the way down to the 2nd and 3rd ribs. The superior region inserts into the lateral end of the clavicle, the middle region inserts onto the acromial end of the clavicle and the inferior region inserts onto the spine of the scapula.
The main action of the trapzius muscles is to stabilise the scapula by keeping it attached to the shoulder girdle. The trapezius muscles can rotate and pull the scapula down and backwards towards the thorax.
Where is the levator scapulae muscle and what is its main function?
It originates from the 3rd-4th cervical segments of the neck and inserts onto the top of the scapula (the corner where the medial and superior borders meet).
As the name suggests, the levator scapulae elevates the scapula by contracting.
where are the rhomboids and what is their main action?
Rhomboid minor is higher up along the back than rhomboid major is. Thus, minor originates from the spinal processes of the 6th and 7th cervical vertebrae and inserts onto the medial border of the scapula.
Rhomboid major originates from the spinal processes of the 1st to 4th thoracic vertebrae and inserts onto the medial border of the scapula.
They both work to pull the scapula inwards towards the middle of the back and downwards onto the thoracic cage.
Where are the deltoids and what is their main action?
The deltoids are split into three parts depending on their site of origin. The clavicular part originates from the lateral third of the clavicle, the acromial part originates from the acromion process of the scapula and the spinal part from the spine of the scapula.
They all insert onto the deltoid tuberosity on the humeral shaft.
The main action of the deltoids is to abduct the arm, when it is medially rotated (facing inwards).
where is the supraspinatus muscle and what is its main action?
The supraspinatus muscle is a rotator cuff muscle.
It originates from the supraspinous fossa of the scapula and inserts onto the greater turbercle of the humerus.
Its main role is early abduction before deltoid rakes over, lateral rotation and tightening of the glenoid fossa.
what is the infraspinatus muscle and what is its main action?
The infraspinatus muscle originates from the infraspinatus fossa of the scapula.
It then crosses over the glenoid fossa to insert onto the greater tubercle.
It’s main role like the other rotator cuff muscles is to tighten the glenoid cavity, and assist with lateral rotation of the arm.
where are the teres major and teres minor muscles? what are their main actions?
teres minor originates from the lateral border of the scapula and inserts onto the greater turbercle of the humerus. It acts as a weak lateral rotator of the arm.
Teres major originates just below teres minor, but still on the inferior angle of the scapula. It then inserts onto the bicipital groove. It acts as a medial rotator and adductor of the humerus and assists the latissimus dorsi in drawing the previously raised humerus downward and backward (extension, but not hyper extension).
where is subscapularis and what is its main action?
Subscapularis is a large triangular muscle that occupies the entire subscapular fossa. The subscapularis muscle originates from the subscapular fossa and inserts onto the lesser turbercle of the humerus.
Its main action is that of medial rotation of the humerus, and tightening of the shoulder joint.
what is coracobrachialis and what is its main function?
Coracobrachialis is a muscle that originates from the corocoid process and inserts onto the crest of the lesser turbercle.
Its main function is to enable anteversion of the humerus, (flexion and abduction of the arm at the same time, as in when your holding a beer).
where are the biceps brachii muscles and what is their main action?
The biceps brachii refers to the two heads, one long head and the other short head that enable flexion of the forearm.
The long head of the biceps originates from the supraglenoid turbercle, and runs through the bicipital groove (a turbercle below the acromion process). The short head originates from the coracoid process. There is the stronger tendon that inserts onto the radial tuberosity and the weaker one becomes a part of the bicipital aponeurosis around the elbow.
where is the brachialis muscle and what is its main action?
The brachialis muscle lies underneath the biceps brachii, and is a powerful forearm flexor.It makes up the floor of the cubital fossa. It originates from the top half of the humerus, close to the deltoid tuberosity. It inserts onto the ulnar tuberosity.
where are the triceps brachii and what is their main function?
The long head originates from the infraglenoid turbercle of the scapula (under the acromion). The medial head originates from the groove of the radial nerve. The lateral short head inserts onto the upper humerus.
They both form one tendon and insert onto the olecranon of the ulna.
Its main function is arm extension.
Name the 4 muscles in the superficial layer of the anterior compartment of the forearm ?
These superficial muscles all arise from the medial epicondyle. They are flexor carpi radialis, palmaris longus, pronator teres and flexi carpi ulnaris.
where is the forearm muscle flexor carpi radialis and what is its main function?
Flexor carpi radialis originates from the medial epicondyle and inserts on the palmar surface of the 2nd metacarpal bone (next to the thumb). It’s main action is flex and abduct the hand.
keep in mind that it is flexor carpi radialis because it passes over the radius bone on the lateral side.
(flexor carpi radialis is the middle finger).
what is the forearm muscle flexor carpi ulnaris and what is its main action?
Flexor carpi ulnaris originates from the medial epicondyle and inserts onto the pisiform carpal bone on the medial side of the bone.
palmar flexion and ulnar adduction
What is the single forearm muscle that makes up the intermediate layer of the anterior superficial compartment?
The flexor digitorum superficialis originates from the top of the ulna below the medial epicondyle and the middle of the radius.
It splits into four long tendons that come off this muscle near the wrist.They travel through the carpal tunnel formed by the flexor retinaculum above. These tendons, along with those of flexor digitorum profundus, are enclosed by a common flexor sheath. The tendons attach to the anterior margins on the bases of the middle phalanges of the four fingers.
Where is the forearm muscle flexor pollicus longus and what is its main action?
Flexor pollicus longus is a flexor of the thumb. It originates from two sites, the anterior surface of the radius, above the radial tuberosity and the interosseous membrane. Its tendon passes through the carpal tunnel and inserts onto the distal phalanx of the thumb.
Where is the forearm muscle flexor digitorum profundus and what is its main action?
Flexor digitorum profundus originates from the upper 3/4 of the anterior and medial surfaces of the ulna and the interosseous membrane. Its tendon passes through the carpal tunnel as one, but splits into four tendons that go and insert onto the distal phalanx of the 4 fingers.
Flexor digitorum profundus enables flexion of the
Where is the muscle pronator quadratus and what is its main action?
Pronator quadratus originates from the distal end of the ulna and inserts onto the distal end of the radius.
It works alongside the pronator teres muscle to pronate the forearm.
Name the six superficial muscles of the posterior forearm. (brachioradialis included).
(Named from lateral to medial border of arm):
Brachioradialis (flexor muscle located in the back), Extensor carpi radialis longis, extensor carpi radialis brevis, extensor digitorum. anconeus and extensor carpi ulnaris.
Name the four deep posterior extensor muscles.
Supinator, abductor pollicis longus, extensor pollicis brevis and extensor pollicis longus.
where is the posterior forearm muscle ‘extensor carpi radialis longus’ found. Does it pass through the extensor retinaculum?
It is the most lateral posterior forearm muscle. It originates from the lateral epicondyle and inserts onto the 2nd metacarpal bone of the palm. (The peter pointer finger).
It passes through the retinaculum’s 2nd compartment.
It is a wrist extensor and wrist abductor
wrist abductor= pulls hand towards radius.
Where is the posterior forearm muscle, ‘extensor carpi radialis brevis’?
Does it pass through the extensor retinaculum and what is its main function?
It sits medially next to radialis longus, and originates from the lateral epicondyle and inserts onto the 3rd metacarpal bone within the palm (the middle finger).
It does pass through the extensor retinaculum and it is also a wrist abductor and extensor.
Where is the muscle ‘extensor digitorum’ ?
Does it pass through the extensor retinaculum and what is its main function?
It originates from the lateral epicondyle and inserts onto the four digits of the hand on the distal phalanges.
It does pass through the extensor retinaculum and its main function is to enable extension of the phalanges, wrist and the elbow.
Where is the posterior forearm muscle ‘extensor digiti minimi’?
Does it pass through the extensor retinaculum and what is its main role?
It originates from the lateral epicondyle and inserts onto the pinky finger.
It does pass through the extensor retinaculum and its main function is to extend the wrist and the pinky finger.
Where is the posterior forearm muscle ‘extensor carpi ulnaris’?
Does it pass through the extensor retinaculum and what is its main function?
wIt originates from the lateral epicondyle and inserts onto the 5th metacarpal bone (the carpal bone for the pinky finger).
It does run through the retinaculum and its main function is the wrist extension and wrist adduction (towards the ulnar side).
Where is the deep posterior muscle ‘supinator’ found ? Does it pass through the extensor retinaculum and what is its main function?
The supinator muscle is a small rectangular muscle that orignates from the top of the radius and inserts horizontally onto the radius. It doesn’t pass through the retinaculum and its main role is to enable supination of the arm (lets the arm turn so the palm is facing upwards), by contracting and pulling the radius back over the ulna.
Where is the forearm muscle ‘extensor pollicis brevis’? Does it pass through the flexor retinaculum and what is its main role?
Extensor pollicis brevis originates from the radius and interosseous membrane because it is a shorter muscle. It inserts onto the middle phalanx of the thumb.
It passes through the first compartment of the extensor retinaculum and its main function is to extend the thumb.
Where is the deep posterior muscle ‘extensor pollicis longus’ and does it pass through the extensor retinaculum?
What is its main function?
Extensor pollicis longus is the longest of the thumb muscles. It originates from the top of the ulna and the interosseous membrane. It inserts onto the distal phalanx of the thumb.
It does pass through the extensor retinaculum.
It enables extension of the thumb.
Where are the lumbricals and what is their main role?
This is the first group of intrinsic hand muscles. There are four (1 for each digit) and they originate from the tendons of flexor digitorum profundus muscles. They then insert onto the radial side of each finger, on the middle row of interphalangeal joints.
Their main role is to enable extension of the interphalangeal joints and flexion of the metacarpophalangeal joints.
What are the interossei muscles and what is their main role?
The interossei muscles are found between the metacarpals of the hand.
There are 4 palmar interossei that are double headed and 3 dorsal interossei that are single headed.
They insert onto the proximal phalanx of their respective digits.
Their main role is to enable flexion at the metacarpophalangeal joints and extension of the interphalangeal joints.
what is the cubital fossa and what are its contents?
The cubital fossa is an triangle located on the anterior surface of the elbow.
The lateral border is the brachioradialis muscle, the medial border is the pronator teres muscle and the superior border is an imaginary line between the medial and lateral epicondyles of the humerus.
The deep brachialis muscle underneath the biceps makes up the floor and the bicipital aponeurosis makes up the roof.
The brachial artery,median nerve, median cubital vein and the biceps tendon are the contents of the cubital fossa. The radial nerve does pass within the vicinity of the fossa, but isn’t strictly part of it.
what is the clinical significance of acromioclavicular separation?
This is when the shoulder is seperated from the chest.
If the acromioclavicular ligaments rip, then the clavicle comes off the acromion and is lifted superiorly by the trapezius muscle. In order for the clavicle to come off the acromion completely though, the coracoclavicular ligaments must also break too.
There are 3 clinical grades for these AC tears, from grades 1-3 with increasing severity.
In which position is the shoulder at most risk of dislocation and what type of dislocation is it?
An anterior dislocation is usually caused by excessive extension and lateral rotation of the humerus. The humeral head is forced anteriorly and inferiorly – into the weakest part of the joint capsule. Tearing of the joint capsule is associated with an increased risk of future dislocations.
Thus, dislocation is mainly anterior, where the humeral head is pushed anteriorally and inferiorally afterwards, so it sits down the front of your armpit.
Posterior dislocations are much more rare, but they can happen.
