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Anatomy Dissection 2: Upper Limb, image image, Terminology …
Anatomy Dissection 2: Upper Limb
Anatomy of the Axilla
What is the Axilla ?
Axilla is the Armpit
It is the Pyramidal Shaped Space between the Glenohumeral Joint at the junction of the Upper Limb and the Thorax.
It is a crucial passage for important neuro-vasculature.
Outline the Borders of the Axilla
Borders:
Apex
Also known as the Axillary Inlet
Formed by the Lateral Border of the First Rib, Superiors Border of the Scapula, Posterior Border of the Clavicle
Medial
Formed by the Serratus Anterior and Thoracic Cage (Ribs and Intercostal Muscles)
Anterior
Formed by the Pectoralis Major, Pectoralis Minor and Subclavius
Posterior
Formed Subscapularis, Teres Major and Latissimus Dorsii
Base
Formed by hair, Skin, Subcutaneous Fat and Axillary Fascia
List the Contents of The Axilla
Contents
Axillary Artery
Axillary Vein
Cords of the Brachial Plexus
Axillary Sheath which encloses the Neurovascular Bundle.
Tendons of the Biceps Brachii (Short Head) and coracobrachialis.
These originate on the Coracoid Process
What is the Axillary Artery ?
Axillary artery is a continuation of the Subclavian Artery
It is divided into 3 parts: Proximal, Middle and Distal by the Pectoralis Minor
Axillary Artery continues as the Brachial Artery at the Lower Border of the Teres Major
Brachial Plexus
What is the Brachial Plexus ?
The Brachial Plexus is a complex intercommunicating network of nerves formed by the Spinal nerves C5, C6, C7, C8, and T1
What does the Brachial Plexus do ?
It supplies Sensory Innervation to most of the Upper Limb and the Axilla
It supplies Motor Innervation to most of the muscles of the Upper Limb and the Shoulder Girdle
It also supplies Autonomic Innervation to the Upper Limb
What does the Brachial Plexus Consist of ?
Roots
Roots are the Anterior (Ventral) Rami of the 5 Spinal Nerves (C5, C6, C7, C8, T1)
Trunks
Roots will then combine to form a Superior Trunk, Middle Trunk and Inferior Trunk
The Trunks are found near the Scalene Muscles of the Neck.
Divisions
Each Trunk is then divided into an Anterior and Posterior Division
These Divisions are found behind the Clavicle
Cords
The Divisions then combine to form the Lateral, Posterior, and Medial Cords
Cords are named according to the Axillary Artery relative to it.
Branches
Cords will then divide, near the 3rd part of the Axillary Artery into Terminal Branches
List the Terminal Branches (MARMU)
Musculocutaneous
Axillary
Radial
Median
Ulnar
Drawing the Brachial Plexus
Brachial Plexus
Roots
There are Five Spinal Roots (C5-C8, T1) which give rise to 3 Nerve Branches
The Dorsal Scapular nerve (Levator Scapulae and Rhomboid)- C5
The Long Thoracic Nerve (Serratus Anterior) - C5, C6, C7
The First Intercostal Nerve - T1
NOTE: C5 Spinal Nerve also gives rise to fibres which join the fibres from C3 and C4 Spinal Nerves to form the Phrenic Nerve
Trunks
The 5 Nerve Roots combine to from 3 Trunks
Superior Trunk is formed from C5 and C6 Spinal Nerve Root
Middle Truck is formed from the C7 Spinal Nerve Root
Inferior Trunk is formed from the C8 and T1 Spinal Nerve Root
NOTE: Superior Trunk also gives rise to 2 Nerve Branches:
Suprascapular Nerve (Supraspinatus and Infraspinatus) - C5 & C6
Nerve to the Subclavius - C5 & C6
The Middle and Inferior Trunk do NOT give rise to extra nerve branches
Divisions
There are 6 Divisions in total, comprising of an Anterior division and a Posterior Divisions from each of the 3 Trunks
Anterior Divisions usually supply the Flexor Muscles
Posterior Divisions usually supply Extensors
NOTE: There are NO extra nerve branches arising from the Divisions
Cords
The Divisions combine to form 3 Cords, which are distributed along the Axillary Artery
Lateral Cord is formed by the Anterior Divisions of the Superior and Middle Trunks
It gives rise to one Nerve Branch: Lateral Pectoral Nerve (C5, C6, C7)
Posterior Cord is formed by the Posterior Divisions of the Superior, Middle and Inferior Trunks.
It gives rise to 3 Nerve Branches: Upper Subscapular Nerve, Lower Subscapular nerve (C5, C6) and Thoracodorsal Nerve (C6, C7, C8)
Medial Cord is formed by the Anterior Division of the Inferior Trunk.
It gives rise to 3 Nerve Branches:
3.1 Medial Pectoral Nerve (C8, T1)
3.2 Medial Brachial Cutaneous Nerves
3.3 Medial Antebrachial Cutaneous Nerve
Terminal Branches
The 3 Cords branch to form 5 Terminal Branches which supply The Upper Limb
Lateral Cord gives rise to the Musculocutaneous Nerve (C5, C6, C7)
Lateral Cord Gives rise to Lateral Root of the Median Nerve
Posterior Cord gives rise to the Axillary Nerve (C5, C6)
Posterior Cord Gives Rise to the Radial Nerve (C5, C6, C7, C8, T1)
Medial cord gives rise to the Medial Root of the Median Nerve (T1)
Medial Cord gives rise to Ulnar Nerve (T1)
DRAW THE BRACHIAL PLEXUS
Clinical Relevance
What is the Clinical Relevance of the Axilla and Brachial Plexus ?
Axilla
Axilla is a common site for measuring temperature
Axilla gives a temp. 0.3 or 0.5 degree Celsius lower than Oral temp.
Brachial Plexus
If the Brachial Plexus of a newborn or adult is Compressed or Stretched
It can result in the following trauma:
Neuropraxia
Neuroma/Rupture
Avulsion
Anatomy of the Upper Anterior Arm
Osteology
Scapula: Supraglenoid Process, Coracoid Process
Humerus, Radius and Ulnar
Muscles
Biceps Brachii
Brachialis
Coracobrachialis
Anatomy of The Anterior Arm
List the Muscles of The Anterior Arm
Biceps Brachii (Short head)
Anterior
Biceps Brachii (Long Head)
Posterior
Coracobrachialis
Directly below top half of Biceps Brachii
Brachialis
Below the stomach of Biceps Brachii, then attaches to Ulnar
Describe the Anterior Muscles of the Upper Arm according to Origin, Insertion, Innervation and Action
Biceps Brachii (Long Head)
Origin: Supraglenoid Tubercle of Scapula
Insertion: Radial Tuberosity and Bicipital Aponeurosis
Innervation: Musculocutaneous Nerve (C5-C6)
Action: Elbow Joint Flexion: Supination, Shoulder joint Flexion. Stabilization of Humeral Head through Deltoid Contraction
Abduction. Internal Rotation of the Humerus
Biceps Brachii (Short Head)
Origin: Coracoid process of Scapula
Insertion: Radial Tuberosity and Bicipital Aponeurosis
Innervation: Musculocutaneous Nerve (C5-C6)
Action: Elbow joint Flexion: Supination. Shoulder Joint flexion. Stabilizes Humeral Head through Deltoid contraction.
Internal rotation. Abduction.
Describe the Anterior Muscle (Brachialis and Coracobrachialis) of the Arm according to Origin, Insertion, Innervation and Action
Brachialis
Origin: Humerus (Distal half of Anterior Surface)
Insertion: Ulnar Tuberosity
Innervation: Musculocutaneous Nerve (C5-C6) and Radial Nerve (C7, Minor)
Action: Flexion at Elbow Joint
Coracobrachialis
Origin: Coracoid process of the Scapula
Insertion: Humerus (In line with crest of lesser tubercle)
Innervation: Musculocutaneous Nerve
Action: Flexion, Adduction, Internal Rotation.
Clinical Relevance
What is the Clinical relevance of The Anterior Arm and Humerus
Anterior Arm
Bicep Bunching/ "Popeye" sign
Rupture of the Long Head of Biceps
Humeral Fractures
Humeral Fractures are due to high energy impact e.g. car accident
May cause impingement of Brachial Plexus
Anatomy of the Anterior Lower Forearm
Flexor Muscles
Osteology
Humerus, radius and ulnar
Carpals, Metacarpals and Phalanges
Muscles
Superficial Muscles
Pronator Teres
Flexor Carpi Radialis
Palmaris longus
Flexor Carpi Ulnaris
Intermediate
Flexor Digitorum Superficialis
Deep Muscles
Flexor Digitorum Profundus
Flexor Pollicis Longus
Pronator Quadratics
Flexor Retinaculum
NOTE:
CMC means Carpometacarpal
DIP means Distal Interphalangeal
PIP means Proximal Interphalangeal
MCP means Metacarpophalangeal
Anterior Compartment of the Forearm
Describe the Superficial Muscles of the Anterior Forearm according to Origin, Insertion, Innervation and Action
Pronator Teres
Origin: Humeral Head (Medial Epicondyle of Humerus) or Ulnar Head (Coronoid Process)
Insertion: Lateral Radius (Distal to Supinator Insertion)
Innervation: Median Nerve (C6, C7)
Action: Weak Flexion of Elbow and Pronator Forearm
Flexor Carpi Radialis
Origin: Medial Epicondyle of Humerus
Insertion: Base of 2nd Metacarpal (Variance: Base of 3rd Metacarpal
Innervation: Median Nerve (C6, C7)
Action: Wrist Flexion and Abduction of hand.
Palmaris Longus
Origin: Medial Epicondyle of Humerus
Insertion: Palmar Aponeurosis
Innervation: Median Nerve (C7, C8)
Action: Weak Flexion of the Elbow
Wrist Flexion tightens Palmar Aponeurosis
Flexor Carpi Ulnaris
Origin: Humeral Head (Medial Epicondyle) and Ulnar Head (Olecranon)
Insertion: Pisiform, hook of hamate. base of 5th Metacarpal.
Innervation: Ulnar nerve (C7-T1)
Action: Wrist Flexion and Abduction of the Hand.
Intermediate Muscles of the Anterior Compartment of the Forearm
Describe the Intermediate Muscles of the Anterior Forearm according to Origin, Insertion, Innervation and Action
Flexor Digitorum Superficialis
Origin:
Humeral-Ulnar Head: Medial Epicondyle of the Humerus and Coronoid Process of Ulnar.
Radial Head: Upper Half of Anterior Border of Radius
Insertion: Side of Middle Phalanges of the 2nd to the 5th Digits.
Innervation: Median Nerve (C8, T1)
Action: Weak Flexion of Elbow
Flexion of Wrist, MCP and PIP Joints of 2nd to 5th digits
Deep Muscles of the Anterior Compartment of the Forearm
Describe the Deep Muscles of the Anterior Forearm according to Origin, Insertion, Innervation and Action
Flexor Digitorum Profundus
Origin: Ulnar and Interosseous Membrane
Insertion: Distal Phalanges of 2nd to 5th Digits
Innervation: Median Nerve (C8, T1) for the radial half of the fingers: 2nd and 3rd digits.
Ulnar Nerve (C8, T1) for the ulnar half of the fingers: 4th and 5th digits.
Action: Flexion of the Wrist, MCP and PIP Joints of the 2nd to 5th Digits.
Flexor Pollicis Longus
Origin: Radius and Interosseous Membrane
Insertion: Distal Phalanx of the Thumb (Palmar Surface)
Innervation: Median Nerve (C8, T1)
Action: Wrist Flexion and Abduction of the Hand
Flexion of the MCP and PIP joints of the Thumb
Pronator Quadratus
Origin: Distal Quarter of the Ulnar (Anterior Surface)
Insertion: Distal Quarter of the Radius ( Anterior Surface)
Innervation: Median nerve (C8, T1)
Action: Pronation of the Hand
Stabilization of the Distal Radioulnar Joint.
Clinical Relevance
Carpal Tunnel Syndrome
Swelling of the Flexor Tendons
Fibrosis or Oedema of the surrounding tissue.
Result in the compression of the Median Nerve
And causes Pain and Paraesthesia in the Median Distribution.
tingling, pricking, chilling, burning, numbness
Anatomy of the Palmar Surface of the Hand
Osteology
Radius, and Ulna
Carpals, Metacarpals and Phalanges
Muscles
Thenar Eminence
Abductor Pollicis Brevis (Superficial)
Flexor Pollicis Brevis (Middle)
Opponenes Pollicis (Inferior)
Hypothenar Eminence
Abductor Digiti Minimi (Superficial)
Flexor Digiti Minimi (Middle)
Opponenes Digiti Minimi (Inferior)
Lumbricals
Interossei
Palmar
Dorsal
Palmar brevis
Adductor Pollicis
Anatomy of the Palmar Surface of the Hand
Describe the Thenar Muscles of the Hand according to Origin, Insertion, Innervation and Action
Abductor Pollicis Brevis
Origin: Scaphoid Bone and Trapezium, Flexor Retinaculum
Insertion: Proximal Base of Thumb Phalanx via Radial Sesamoid
Innervation: Median nerve (C8, T1)
Action: Abduction of CMC Joint of Thumb
Flexor Pollicis Brevis
Origin:
Superficial Head: Flexor Retinaculum
Deep head: Capitate Bone of the Trapezium
Insertion: Proximal Base of Thumb Phalanx via the Sesamoid
Innervation:
Superficial Head: Median Nerve (C8, T1)
Deep Head: Ulnar Nerve (C8, T1)
Action: Flexion of the CMC Joints of the Thumb.
Opponens Pollicis
Origin: Trapezium
Insertion:1st metacarpal (Radial Border)
Innervation: Median nerve (C8, T1)
Action: Opposition of CMC Joints of Thumb
Describe the Hypothenar Muscles of the Hand according to Origin, Insertion, Innervation and Action
Abductor Digiti Minimi
Origin: Pisiform Bone
Insertion: 5th Proximal Phalanx (Ulnar Base) and Dorsal Digital Expansion of 5th Digit.
Innervation: Ulnar nerve (C8, T1)
Action: Abduction and Flexion of the MCP Joints of the Little Finger
Extension of the PIP and DIP Joints of the Little Finger
Flexor Digiti Minimi Brevis
Origin: Hook of Hamate and Flexor retinaculum
Insertion: 5th Proximal Phalanx (Base)
Innervation: Ulnar nerve (C8, T1)
Action: Flexion of the MCP Joints of the Little Finger.
Opponens Digiti Minimi
Origin: Hook of Hamate and Flexor Retionaculum
Insertion: 5th Metacarpal (Ulnar Border)
Innervation: Ulnar Nerve (C8, T1)
Action: Draws Metacarpals in Palma Direction (Opposition)
Lumbricals
There are 4 Lumbrical muscles in total.
Start at 2nd digit and end at 5th Digit
First and Second Lumbricals are Unipennate
Third and Fourth lumbricals are Bipennate
Describe the Metacarpals Muscles of the Hand according to Origin, Insertion, Innervation and Action
Lumbricals
1st Lumbrical
Origin: Tendon of the Flexor Digitorum Profundus (Radial Side)
Insertion: Dorsal Digital Expansion of 2nd Digit
Innervation: Median Nerve (C8, T1)
Action: Flexion of MCP Joints
Extension of the Proximal and Distal IP (Interphalangeal) Joints
2nd Lumbrical
Origin: Tendons of the Flexor Digitorum Profundus (Radial Side)
Insertion: Dorsal Digital Expansion of 3rd Digit
Innervation: Median Nerve (C8, T1)
Action: Flexion of the MCP Joints
Extension of the Proximal and Distal IP Joints
3rd Lumbrical
Origin: Tendon of the Flexor Digitorum Profundus (Bipennate from Medial and Lateral Side)
Insertion: Dorsal Digital Expansion of 4th Digit
Innervation: Ulnar Nerve (C8, T1)
Action: Flexion of the MCP Joints
Extension of the Proximal and Distal IP Joints
4th Lumbrical
Origin: Tendon of the Flexor Digitorum Profundus (Bipennate from Medial and Lateral Side)
Insertion: Dorsal Digital expansion of the 5th Digit
Innervation: Ulnar nerve (C8, T1)
Action: Flexion of the MCP Joints
Extension of the Proximal and Distal IP Joints.
Dorsal Interossei
DAB - Dorsal interossei are responsible for Abduction
Describe the Dorsal Interossei Muscles of the Hand according to Origin, Insertion, Innervation and Action
1st Dorsal Interossei
Origin: 1st and 2nd Metacarpal (Adjacent Sides, Two Heads)
Insertion: 2nd Digit (DDE)
Proximal Phalanx of 2nd Digit (Radial Side)
Innervation: Ulnar Nerve (C8, T1)
Action: Flexion of MCP joints
2nd Dorsal Interossei
Origin: 2nd and 3rd Metacarpals (Adjacent Sides, Two Heads)
Insertion: 3nd Digit (DDE)
Proximal Phalanx of 3rd Digit (Radial Side)
Innervation: Ulnar Nerve (C8, T1)
Action: Flexion of MCP Joints
Extension and Abduction of Proximal and Distal IP Joints
3rd Dorsal Interossei
Origin: 3rd and 4th Metacarpal (Adjacent Side, Two Heads)
Insertion: 3rd Digit (DDE)
Proximal Phalanx of 3rd Digit (Ulnar Side)
Innervation: Ulnar Nerve (C8, T1)
Action: Flexion of MCP Joints
Extension and Abduction of Proximal and Distal IP Joints
4th Dorsal Interossei
Origin: 4th and 5th Metacarpal (Adjacent Side, Two Heads)
Insertion: 4th Digit (DDE)
Proximal Phalanx of 4th Digit (Ulnar Side)
Innervation: Ulnar Nerve (C8, T1)
Action: Flexion of MCP Joints
Extension and Abduction of Proximal and Distal IP Joints
Palmaris Interossei
PAD - Palmaris Interossei are responsible for Adduction
Palmaris Interossei are found on the sides where there are NO Dorsal interossei
Describe the Palmaris Interossei Muscles of the Hand according to Origin, Insertion, Innervation and Action
1st Palmaris Interossei
Origin: 2nd Metacarpal (Direction: Ulnar Side)
Insertion: 2nd Digit (DDE)
Proximal Phalanx of 2nd Digit (base)
Innervation: Ulnar Nerve (C8, T1)
Action: Flexion of MCP Joints
2nd Palmaris Interossei
Origin: 4rd Metacarpal (Radial Side)
Insertion: 4th Digit (DDE)
Proximal Phalanx of 4th Digit (Base)
Innervation: Ulnar Nerve (C8, T1)
Action: Flexion of MCP Joints
Extension and Adduction of Proximal and Distal IP Joints
3rd Palmaris Interossei
Origin: 5th Metacarpal (Radial Side)
Insertion: 5th Digit (DDE)
Proximal Phalanx of 5th Digit (Base)
Innervation: Ulnar Nerve (C8, T1)
Action: Flexion of MCP Joints
Extension and Adduction of Proximal and Distal IP Joints
Adductor Pollicis
Describe the Adductor Pollicis Muscle of the Hand according to Origin, Insertion, Innervation and Action
Origin:
Transverse Head: 3rd Metacarpal(Palmar surface)
Oblique Head: Capitate, 2nd and 3rd Metacarpals Base.
Insertion: Thumb (Base of Proximal Phalanx) via Ulnar Sesamoid
Innervation:
Transverse Head: Medial Nerve (C8, T1)
Oblique Head: Ulnar Nerve (C8, T1)
Action: Adduction of CMC Joints
Flexion of MCP Joints
Palmaris Brevis
Describe the Palmaris Brevis Muscle of the Hand according to Origin, Insertion, Innervation and Action
Origin: Palmar Aponeurosis (Ulnar Border)
Insertion: Skin of Hypothenar Eminence
Innervation: Ulnar (C8, T1)
Action: Tightens the Palmar Aponeurosis (Protective Function)
Terminology
Pollicis - Thumb
Digiti minimi - Little Finger
Lumbrical - Wormlike
Interossei - Between Bones
