Lecture 18 Flashcards
What is the Flexor compartment of the arm?
Anterior comartment
What is the Extensor compartment of the arm?
Posterior Compartment
What are the anterior and posterior compartments of the arm divided by?
Medial and Lateral intermuscular septae
What are 2x features of the intermuscular septae of the humerus?
Septa attached to medial and lateral supracondylar ridges(lines) of humerus
Septa fade out in upper part of arm
Continuous with deep fascia
What 3x muscles make up the bulk of the front of the arm?
Coracobrachialis
Brachialis
Biceps Brachii
-all innervated by the musculocutaneous nerve
What is the relative position of musculocutaneous nerve to the 3x muscles it innervates on the bulked front of the arm?
Coracobrachialis -through
Brachialis -lies on
Biceps Brachii - underneath
What 2x muscles originate from the coracoid process and are partially attached to one another?
Coracobrachilais
Short head of biceps
Where does the Long head of biceps Brachii originate from?
Supraglenoid tubercle
Where does brachialis originate from?
front of humerus
-oppostie deltoid tuberosity
What does brachialis cover and attach to?
Brachialis covers anterior aspects of elbow joint
attches to coracoid process and tuberosity of the ulna
Where are the 2x insertions of Biceps Brachii?
Strong tendinous insertion into the tuberosity of the radius
Bicepital aponeuorosis into the deep fascia onto the anterio-medial aspect of the forearm
What is the pathway of the ulna nerve?
Behind medial intermuscular septum in lower 1/3 of arm
accompanies superior ulnar collateral artery
Behing medial epicondyle of humerus
Enters Forearm between 2x head of flexor carpi ulnaris
What is the relationship between the median nerve and ulnar nerve and the arm?
Neither the median nerve or ulna nerve have any branches into the arm
What are the vena comitantes reinforced by?
Basilic vein
-which pierces deep fascia half way up the arm
Where does the basilic vein pierce the deep fascia?
Half way up the arm
What is the pathway of the cephalic vein?
Lies in subcutaneous tissue
Travels up anterolateral aspect of arm
Into the groove between the anterior fibres of deltoid and pectoralis major (deltopectoral groove)
joins axillary vein (via piercing clavipectoral fascia)
What 7 muscles run from the pectoral girdle –> arm?
- Deltoid
- Teres Major
- Coracobrachilais
Rotator Cuff Muscles - Supraspinatis
- Infraspinatis
- Teres Minor
- Subscapularis
What 2x muscles bypass the arm and run from the Pectoral girdle –> to the forearm?
Biceps Brachii
Triceps Brachii
What 2x muscles run from the Arm –> forearm?
Brachilais
Triceps - Lateral and Medial Head
Deltoid
Large powerful Lateral muscle
Delta = traingle
3x muscle fibres (Anterior, Posterior and Middle fibres)
Origin: anatomical Horseshoe (distal end of clavicle, acromium and spine)
Insertion: 1/2 way down humerus, on lateral deltoid tuberosity
-roughened area
Axillary Nerve
What are the Key features about the anterior fibres of deltoid?
Unipennate
=strong (non parallel arangement of fibres increasing/impacting on strength)
Primary: Flex shoulder + internally rotates arm
What are the Key features about the Posterior fibres of deltoid?
Unipennate
=strong
Primary: Extend shoulder Externally rotates arm
-almost complete antagonist to anterior fibres
What are the Key features about the middle fibres of deltoid?
Multipennate (very strong)
Abducts arm
How does the position of the limb affect the deltoid?
Position of the limb, affect whether with the middle fibres, the anterior and posterior fibres either help or not help with ABD abduction
- Alone: Middle fibres will ABDuct, and pass imaginary line/15 degree buffer zone with subscapularis firing
- stationary(behind imaginary line): posterior and anterior fibres with ABDuct
- already Abducted arm = Anterior and posterior fibres shorten and assist with abduction
Teres Major
O: inferior angle of scapula
I: Medial lip of inter tubercular groove
-twisting around Teres Major = Insertion of Lat Dorsi
Teres Major + Lat Dorsi= Posterior fold of axilla
-Internal Rotation + Extends shoulder
Teres Major inferior border= boundary between Axillary and Brachial structures
Lower Subscapular nerve
What is the does the Inferior border of Teres major form?
Boundary between Axillary structures and Brachial structures
Triceps Brachii
3x Heads Lateral, Long + Medial(under)
Long head: Infraglenoid Tubercle –> b/w teres major(front) and teres minor (behind)
-below glenoid of scapula. Extra capsular
-Shunt muscle (weak)
Lateral + Medial head =arise from back of humerus
Lateral and long head contribute to supernation and pronation)
Medial head does most of work (Like Brachialis)
All merge to form strong tendinous insertion of Olecranon of Ulna (posterior)
Extensors of Elbow
-Assisted by Anconeous (extensor of forearm (and triceps))
Radial Nerve
Profunda Brachii artery
What is the Nerve supply for the extensor compartment of the shoulder?
Radial Nerve
Where is Quadrangular space located?
Lateral Side
Teres Major inferiory
Teres minor Superiorly
Humerus Laterally
Where is Triangular space located?
Medial side
Teres Minor and Major above and below respectively
What passes through the Quadrangular space?
axillary nerve
posterior humeral circumflex
What passes through the Triangular space?
Branch of circumflex scapula artery
Where is Triangular Interval located?
below teres major
between long and lateral heads of biceps brachii
What is the pathway of the Radial nerve and Profunda brachii?
infront of teres major –> pass to back of arm
Revealed from behind Triangular Interval
–> Back of humerus. Lying on origin of Medial head of triceps (in radial/spiral groove)
What is the pathway of the Ulna nerve?
supplies no structures in the arm
Medial side of posterior compartment with Superior Ulnar collateral artery(branch off brachial artery arising just below profunda)
What is the Superior Ulnar Collateral Artery?
branch off brachial artery, arising just below Profunda
Biceps Brachii
2x heads (long and short)
Long head = Supraglenoid tubercle = Intracapsular (inside shoulder joint = stabilises shoulder joint = Poppii muscle
Short head = coracoid (with Coracobrachialis)
Common insertion = Radial tuberosity + Bicepiteal Aponeurosis
-Primarily Supinator (feel) + Elbow Flexor
Musculocutaneous nerve
What 2x Anterior Arm muscles attach to the coracoid?
Short head of Biceps Brachii
+ Coracobrachilais
Brachialis
O: Anterior Distal Humerus (including intermuscular septa)
I: Tuberosity of the Ulna
-Pushes up Biceps Brachii when you flex elbow
Main elbow Flexor- cannot do anything else
Musculocutaneous nerve
Coracobrachialis
Musculocutaneous nerve landmark
O: Coracoid (with Short head biceps brachii)
I: Medial side of Humerus
ADDuction fo shoulder (+ flexion of shoulder)
What is bigger, a Trichanter or a tubercle?
Tubercle = big trichanter
What do the greater and lesser tubercles of the Humerus form?
Bicepital /Intertubercular groove
Anterior surface of humerus
-Where long head of biceps Brachii runs down
What muscles insert to the lateral lip of biceptial groove of the humerus?
Insertion of Pec Major
What muscles insert to the floor and medial lip of biceptial groove of the humerus?
Latissimus Dorsi (comes from posteriorly)
- forms Floor of biceptial groove
- posterior fold of axilla
What muscles insert to the medial lip of biceptial groove of the humerus?
Teres Major (and Lat dorsi)
What tendon runs down the Bicepital groove?
Tendon of long head of Biceps Brachii
What does “Lady lies between 2x majors” mean?
Lady = Lat Dorsi
2x majors= Pec Major + Teres Major
-order of Intertubercular groove
-Lateral –> Medial
Where is the true formation of Arm compartments?
After insertion of Deltoid Tuberosity and Coracobrachialis
Established by Intermsucular septa (Medial and Lateral)
-Dont start forming until after D and C insertions
Intermuscular septa = continuous with Periosteum/Deep brachial fascia
-Divides into Anterior Flexor compart. and Posterior Extensor compart.
-Allows for more realestate for muscle to attach to
(e.g. Brachilais = more SA = more Pull on arm
What is the Anterior Flexor compartment of the arm’s innervation?
Musculocutaneous nerve
What is the Posterior Extensor compartment of the arm’s innervation?
Radial Nerve
-Only Triceps BRachii
What are important features of the Hands?
Dextress =fine motor controls
+ Power = strong grip
Large Movement
Cannot have big bulky muscles on a dextress structure
-therefore the forearm contains the strong power muscles of wrist and hand
-Tendons LONG and OFFSITE
Muscles have to be quite long, shorten 1/3 during contraction
-therefore to have Alot of movement your 1/3 needs to be really big
-Operation offsite/Remote control
What occurs at the distal part of the humerus?
Establishment of compartments that belong to Forearm
Forearm muscles originate from the arm (sides of elbow/epicondyles), (as anterior and posterior compartment are occupying realestate)
Then their tendons cross the wrist
What are the articular surfaces of the elbow?
Condyles
-curved articular surfaces of the elbow
+ their Epicondyles where most of the forearm muscles originate from
Where do most of the Forearm muscles originate from?
Epicondyles of the condyles of the humerus
-(Forearm muscles originate from the arm (sides of elbow/epicondyles), (as anterior and posterior compartment are occupying realestate)
Then their tendons cross the wrist)
What do the forearm muscles act upon?
arm and wrist
- cross 2x joints
- originate above elbow joint (on epicondyles of humerus)
- insert below wrist joint, after crossing wrist joint
Which muscle is attached to the intermuscular septa?
Brachialis
What are Biceps Brachialis and Brachialis innervated b?
Musculocutaneous nerve
-as Anterior flexor compartment
What are extensor Carpi radialis and Brachioradialis innervated by?
Radial Nerve
What are the 3x Anterior compartments muscles of the arm?
Biceps Brachii (2x heads)
Brachialis
Coracobrachialis
What is the Poppi muscle?
Long head of Biceps Femoris Ruptured
-main stabilise shoulder joint
- Not sesmoid bone
-does have synovial membrane + another tendon ontop
-but Rupturing due to bone movement around it
=Poppi muscle (distinctive buldge)
Olecranon
Posterior Ulna boney Prominence
- Insertion of Triceps Brachii
- allows Extension of Elbow
Radial Groove of Humerus
Between Lateral and Medial heads of Triceps Brachii
Anconeus
O: Posterior Lateral Epicondyle
I: Posterior Ulna (distal to olecranon)
Forearm extensor Muscle
-aids Extension of triceps brachii
