Anatomy Flashcards
Origin, insertion, action, innervation, blood supply + description of the platysma
Origin: It has two heads, which originate from the fascia of the pectoralis major and deltoid.
Insertion: inferior border of the mandible
Action: pulling down mandible + lips
Innervation: cervical branch of the facial nerve
Blood supply: submental + suprascapular artery
Description: The platysma is a broad superficial muscle which lies anteriorly in the neck.
Origin, insertion, action, innervation + blood supply of sternocleidomastoid
Origin: Sternal head originates from the manubrium of the sternum
Clavicular head originates from the medial third of the clavicle
Insertion: mastoid process of the temporal bone and the superior nuchal line of the occipital bone
Action: Lateral flexion and rotation of the neck when acting unilaterally, and extension of the neck at the atlanto-occipital joints when acting bilaterally.
Innervation: Accessory nerve
Blood supply:
Upper third – Occipital artery
Middle third – Superior thyroid artery and external carotid artery
Lower third – Suprascapular artery
Origin, insertion + action of the scalenes
Anterior, middle + posterior scalene
Origin: transverse processes of C2-C7
Insertion: rib 1 + 2
Action: flexion of neck + accessory muscle of respiration
Origin, insertion, action, innervation, blood supply + description of levator scapulae
Origin: transverse processes of the C1-C4 vertebrae
Insertion: medial border of the scapula
Action: Elevation of the scapula.
Innervation: Dorsal scapular nerve
Blood supply: Dorsal scapular artery.
Description: extrinsic muscle of the back.
Origin, insertion, action, innervation, blood supply + description of trapezius
Origin: skull, nuchal ligament and the spinous processes of C7-T12
Insertion: clavicle, acromion, and the scapula spine
Action: Abduction of the upper limb at the shoulder (by rotating the scapula). The upper fibres of trapezius also elevate the scapula, the middle fibres retract, and the lower fibres depress.
Innervation: Accessory nerve
Blood supply: Transverse cervical artery
Description: extrinsic muscle of the shoulder. It is a broad, flat and triangular shape – forming a trapezoid shape in combination with the contralateral side.
Origin, insertion, action, innervation + blood supply of latissimus dorsi
Origin: spinous processes of T7-T12, iliac crest, thoracolumbar fascia and the inferior three ribs
Insertion: The fibres converge into a tendon that attaches to the intertubercular sulcus of the humerus
Action: Extension, adduction and internal rotation of the upper limb at the shoulder.
Innervation: Thoracodorsal nerve.
Blood supply: Thoracodoral artery.
Origin, insertion, action, innervation, blood supply + description of the rhomboids
There are two rhomboid muscles – major and minor. The rhomboid minor is situated superiorly to the major.
Origin:
Minor: spinous processes of C7-T1 vertebrae
Major: spinous processes of T2-T5 vertebrae
Insertion: medial border of the scapula
Action: Retracts and rotates the scapula.
Innervation: Dorsal scapular nerve.
Blood supply: Dorsal scapular artery
What are the extrinsic muscles of the shoulder?
Originate from torso and attach to shoulder
Superficial: trapezius, latissimus dorsio
deep: levator scapulae, rhomboids
What are the intrinsic muscles of the shoulder?
Originate from scapula/ clavicle and attach to humerus
Deltoid, teres major, rotator cuff muscles
Origin, insertion, action, innervation, blood supply + description of deltoid
Origin: lateral third of the clavicle, the acromion and the spine of the scapula
Insertion: deltoid tuberosity on the lateral aspect of the humerus
Action:
Anterior fibres – flexion and medial rotation.
Posterior fibres – extension and lateral rotation.
Middle fibres – the major abductor of the arm (takes over from the supraspinatus, which abducts the first 15 degrees).
Innervation: Axillary nerve.
Blood supply: anterior + posterior circumflex humeral artery
Description: The deltoid muscle is shaped like an inverted triangle. It can be divided into an anterior, middle and posterior part.
Origin, insertion, action, innervation, blood supply + description of teres major
Origin: posterior surface of the inferior angle of the scapula
Insertion: medial lip of the intertubercular groove of the humerus.
Action: Adducts and extends at the shoulder, and internally rotates the arm
Innervation: Lower subscapular nerve
Blood supply: thoracodorsal artery, posterior circumflex humeral artery
Description: The teres major forms the inferior border of the quadrangular space – the ‘gap’ that the axillary nerve and posterior circumflex humeral artery pass through to reach the posterior scapular region.
Origin, insertion, action, innervation + blood supply of supraspinatus
Origin: supraspinous fossa of the scapula
Insertion: greater tubercle of the humerus
Action: Abduction of the upper limb at the shoulder. It performs the first 0-15o of abduction, and assists the deltoid muscle for 15-90o
Innervation: Suprascapular nerve.
Blood supply: suprascapular artery
Origin, insertion, action, innervation + blood supply of infraspinatus
Origin: infraspinous fossa of the scapula
Insertion: greater tubercle of the humerus
Action: Laterally rotates the arm.
Innervation: Suprascapular nerve.
Blood supply: suprascapular + circumflex artery
Origin, insertion, action, innervation + blood supply of subscapularis
Origin: subscapular fossa, on the costal surface of the scapula
Insertion: lesser tubercle of the humerus
Action: Medially rotates the arm.
Innervation: Upper and lower subscapular nerves.
Blood supply: subscapular artery
Origin, insertion, action, innervation + blood supply of teres minor
Origin: posterior surface of the scapula, adjacent to its lateral border
Insertion: greater tubercle of the humerus
Action: Laterally rotates the arm
Innervation: Axillary nerve.
Blood supply: circumflex scapular + posterior circumflex humeral artery
Origin, insertion, action, innervation, blood supply + description of pec major
Origin:
Clavicular head – originates from the anterior surface of the medial clavicle.
Sternocostal head – originates from the anterior surface of the sternum, the superior six costal cartilages and the aponeurosis of the external oblique muscle.
Insertion: intertubercular sulcus of the humerus.
Action: Adducts and medially rotates the upper limb and draws the scapula anteroinferiorly. The clavicular head also acts individually to flex the upper limb.
Innervation: Lateral and medial pectoral nerves.
Blood supply: thoracoacromial, superior + lateral thoracic artery
Description:
The pectoralis major is the most superficial muscle in the pectoral region. It is large and fan shaped, and is composed of a sternal head and a clavicular head:
Origin, insertion, action, innervation, blood supply + description of pec minor
Origin: 3rd-5th ribs
Insertion: coracoid process of the scapula.
Action: Stabilises the scapula by drawing it anteroinferiorly against the thoracic wall.
Innervation: Medial pectoral nerve.
Blood supply: thoracoacromial artery
Description: The pectoralis minor lies underneath its larger counterpart muscle, pectoralis major. Both muscles form part of the anterior wall of the axilla region.
Origin, insertion, action, innervation, blood supply + description of serratus anterior
Origin: lateral aspects of ribs 1-8
Insertion: costal (rib facing) surface of the medial border of the scapula
Action: Rotates the scapula, allowing the arm to be raised over 90 degrees. It also protracts the scapula, holding it against the ribcage.
Innervation: Long thoracic nerve.
Blood supply: thoracodorsal, superior + lateral thoracic artery
Description: serratus anterior is located more laterally in the chest wall and forms the medial border of the axilla region.
Origin, insertion, action, innervation, blood supply + description of subclavius
Origin: junction of the 1st rib and its costal cartilage
Insertion: inferior surface of the middle third of the clavicle
Action: Anchors and depresses the clavicle
Innervation: Nerve to subclavius
Blood supply: thoracoacromial artery
Description: subclavius is small muscle, which is located directly underneath the clavicle, running horizontally. It affords some minor protection to the underlying neurovascular structures
Origin, insertion, action, innervation, blood supply + description of brachialis
Origin: medial and lateral surfaces of the humeral shaft
Insertion: ulnar tuberosity, just distal to the elbow joint.
Action: Flexion at the elbow.
Innervation: Musculocutaneous nerve, with contributions from the radial nerve.
Blood supply: brachial + radial artery
Description: brachialis muscle lies deep to the biceps brachii, and is found more distally than the other muscles of the arm. It forms the floor of the cubital fossa.
What does winging of the scapula indicate?
Long thoracic nerve palsy causing paralysis of serratus anterior
often from traction injury
What muscles are in the anterior compartment of the upper arm?
biceps brachii, brachialis, coracobrachialis
Origin, insertion, action, innervation + blood supply of biceps brachii
Origin: Long head originates from the supraglenoid tubercle of the scapula, and the short head originates from the coracoid process of the scapula
Insertion: radial tuberosity and the fascia of the forearm via the bicipital aponeurosis.
Action: Supination of the forearm. It also flexes the arm at the elbow and at the shoulder.
Innervation: Musculocutaneous nerve. The bicep tendon reflex tests spinal cord segment C6.
Blood supply: brachial artery
Origin, insertion, action, innervation, blood supply + description of coracobrachialis
Origin: coracoid process of the scapula
Insertion: medial side of the humeral shaft, at the level of the deltoid tubercle
Action: Flexion of the arm at the shoulder, and weak adduction.
Innervation: Musculocutaneous nerve
Blood supply: brachial artery
Description: coracobrachialis muscle lies deep to the biceps brachii in the arm
Origin, insertion, action, innervation + blood supply of triceps brachii
Origin:
Long head originates from the infraglenoid tubercle of the scapula.
Lateral head originates from the humerus (superior to the radial groove).
Medial head originates from the humerus (inferior to the radial groove).
Insertion: converge into one tendon which inserts onto the olecranon of the ulna
Action: Extension of the arm at the elbow.
Innervation: Radial nerve. A tap on the triceps tendon tests spinal segment C7.
Blood supply: deep brachial artery
Origin, insertion, action, innervation, blood supply + description of serratus posterior superior
Origin: lower part of the ligamentum nuchae, and the cervical and thoracic spines (usually C7 – T3).
Insertion: ribs 2-5
Action: Elevates ribs 2-5
Innervation: Intercostal nerves.
Blood supply: Posterior intercostal arteries.
Description: serratus posterior superior is a thin, rectangular shaped muscle. It lies deep to the rhomboid muscles on the upper back
Origin, insertion, action, innervation, blood supply + description of serratus posterior inferior
Origin: thoracic and lumbar spines (usually T11 – L3)
Insertion: ribs 9-12
Action: Depresses ribs 9-12.
Innervation: Intercostal nerves.
Blood supply: posterior intercostal arteries, subcostal artery, and upper lumbar arteries.
Description: The serratus posterior inferior is broad and strong. It lies underneath the latissimus dorsi.
Origin, insertion, action, innervation + blood supply of Splenius Capitis
Origin: lower aspect of the ligamentum nuchae, and the spinous processes of C7 – T3/4 vertebrae
Insertion: mastoid process and the occipital bone of the skull
Action: Rotate head to the same side
Innervation: Posterior rami of spinal nerves C3 and C4
Origin, insertion, action, innervation + blood supply of Splenius Cervicis
Origin: spinous processes of T3 – T6 vertebrae
Insertion: transverse processes of C1-3/4.
Action: Rotate head to the same side
Innervation: Posterior rami of the lower cervical spinal nerves
Origin, insertion, action, innervation, blood supply + description of iliocostalis
Origin: common tendinous origin
Insertion: costal angle of the ribs and the cervical transverse processes
Action: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head.
Innervation: Posterior rami of the spinal nerves
Description: The iliocostalis muscle is located laterally within the erector spinae. It is associated with the ribs, and can be divided into three parts – lumborum, thoracis, and cervicis.
Origin, insertion, action, innervation, blood supply + description of longissimus
Origin: common tendinous origin
Insertion: lower ribs, the transverse processes of C2 – T12, and the mastoid process of the skull.
Action: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head.
Innervation: Posterior rami of the spinal nerves.
Description: The longissimus muscle is situated between the iliocostalis and spinalis. It is the largest of the three columns. It can be divided into three parts – thoracic, cervicis and capitis.
Origin, insertion, action, innervation, blood supply + description of spinalis
Origin: common tendinous origin
Insertion: spinous processes of C2, T1-T8 and the occipital bone of the skull.
Action: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head
Innervation: Posterior rami of the spinal nerves.
Description: The spinalis muscle is located medially within the erector spinae. It is the smallest of the three muscle columns. It can be divided into the thoracic, cervicis and capitis (although the cervicis part is absent in some individuals).
Origin, insertion, action, innervation, blood supply + description of semispinalis
Origin: transverse processes of C4-T10
Insertion: spinous processes of C2-T4, and to the occipital bone of the skull.
Action: Extends and contralaterally rotates the head and vertebral column.
Innervation: Posterior rami of the spinal nerves.
Description: The semispinalis is the most superficial of the deep intrinsic muscles. Much like the intermediate muscles, it can be divided by its superior attachments into thoracic, cervicis and capitis.
Origin, insertion, action, innervation, blood supply + description of multifidus
Origin: broad origin – arises from the sacrum, posterior iliac spine, common tendinous origin of the erector spinae, mamillary processes of lumbar vertebrae, transverse processes of T1-T3 and articular processes of C4-C7.
Insertion: vertebral spinous processes.
Action: Stabilises the vertebral column.
Innervation: Posterior rami of the spinal nerves.
Description: The multifidus is located underneath the semispinalis muscle. It is most developed in the lumbar area.
Origin, insertion, action, innervation, blood supply + description of rotatores
Origin: vertebral transverse processes.
Insertion: lamina and spinous processes of the vertebrae above.
Action: Contributes to extension and rotation of the vertebral column. Also stabilises the vertebrae and had a proprioceptive function.
Innervation: Posterior rami of the spinal nerves
Description: The rotatores are the deepest muscles of the transversospinales group. They are most prominent in the thoracic region.
Origin, insertion, action, innervation + blood supply of Flexor Carpi Ulnaris
Origin: The humeral head originates from the medial epicondyle of the humerus with the other superficial flexors, whilst the ulnar head originates from the olecranon of the ulna.
Insertion: The muscle tendon passes into the wrist and attaches to the pisiform bone, hook of hamate, and base of the 5th metacarpal
Action: Flexion and adduction at the wrist.
Innervation: Ulnar nerve.
Blood supply: ulnar artery
What is the erector spinae, and what is its origin?
the iliocostalis, longissimus and spinalis. Together these muscles form a column, known as the erector spinae.
The erector spinae is situated posterolaterally to spinal column
All three muscles can be subdivided by their superior attachments (into lumborum, thoracic, cervicis and capitis). They also all have a common tendinous origin, which arises from:
Lower thoracic and lumbar vertebrae
Sacrum.
Posterior aspect of iliac crest.
Sacroiliac and supraspinous ligaments.
What is the transversospinales?
The deep intrinsic muscles are located underneath the erector spinae, and are known collectively as the transversospinales. They are a group of short muscles, associated with the transverse and spinous processes of the vertebral column.
There are three major muscles in this group – the semispinalis, multifidus and rotatores.
What are the minor deep intrinsic muscles of the back?
Interspinales – Spans between adjacent spinous processes. Acts to stabilise the vertebral column.
Intertranversarii – Spans between adjacent transverse processes. Acts to stabilise the vertebral column.
Levatores costarum – Originates from the transverse processes of C7-T11, and attaches to the rib immediately below. Acts to elevate the ribs.
Origin, insertion, action, innervation + blood supply of Palmaris Longus
Origin: medial epicondyle
Insertion: flexor retinaculum of the wrist.
Action: Flexion at the wrist.
Innervation: Median nerve.
Blood supply: ulnar artery
Origin, insertion, action, innervation + blood supply of Flexor Carpi Radialis
Origin: medial epicondyle
Insertion: base of metacarpals II and III.
Action: Flexion and abduction at the wrist.
Innervation: Median nerve.
Blood supply: ulnar artery
Origin, insertion, action, innervation + blood supply of Pronator Teres
Origin: It has two origins, one from the medial epicondyle, and the other from the coronoid process of the ulna
Insertion: laterally to the mid-shaft of the radius.
Action: Pronation of the forearm.
Innervation: Median nerve.
Blood supply: ulnar artery
Origin, insertion, action, innervation, blood supply + description of flexor digitorum superficialis
Origin: two heads – one originates from the medial epicondyle of the humerus, the other from the radius
Insertion: muscle splits into four tendons at the wrist, which travel through the carpal tunnel, and attach to the base of the middle phalanx of the four digits.
Action: Flexes the metacarpophalangeal joints and proximal interphalangeal joints at the 4 fingers, and flexes at the wrist.
Innervation: Median nerve.
Blood supply: ulnar artery
Description: The flexor digitorum superficialis is the only muscle of the intermediate compartment. It can sometimes be classed as a superficial muscle, but in most individuals, it lies between the deep and superficial muscle layers.
The muscle is a good anatomical landmark in the forearm – the median nerve and ulnar artery pass between its two heads, and then travel posteriorly.
Origin, insertion, action, innervation + blood supply of Flexor Digitorum Profundus
Origin: ulna and associated interosseous membrane.
Insertion: At the wrist, it splits into four tendons, that pass through the carpal tunnel and attach to the distal phalanges of the four fingers.
Action: It is the only muscle that can flex the distal interphalangeal joints of the fingers. It also flexes at metacarpophalangeal joints and at the wrist.
Innervation: The medial half (acts on the little and ring fingers) is innervated by the ulnar nerve. The lateral half (acts on the middle and index fingers) is innervated by the anterior interosseous branch of the median nerve.
Blood supply: ulnar artery
What are the muscles in each layer of the anterior compartment of the forearm?
Superficial: flexor carpi ulnaris, palmaris longus, flexor carpi radialis, pronator teres.
Intermediate: flexor digitorum superficialis.
Deep: flexor digitorum profundus, pronator quadratus, flexor pollicis longus
Origin, insertion, action, innervation + blood supply of Flexor Pollicis Longus
This muscle lies laterally to the flexor digitorum profundus
Origin: anterior surface of the radius and surrounding interosseous membrane.
Insertion: base of the distal phalanx of the thumb.
Action: Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb.
Innervation: Median nerve (anterior interosseous branch).
Blood supply: ulnar artery
Origin, insertion, action, innervation + blood supply of Pronator Quadratus
A square shaped muscle found deep to the tendons of the flexor digitorum profundus and flexor pollicis longus.
Origin: anterior surface of the ulna
Insertion: anterior surface of the radius
Action: Pronates the forearm.
Innervation: Median nerve (anterior interosseous branch).
Blood supply: ulnar artery
Description, Origin, insertion, action, innervation + blood supply of brachioradialis
The brachioradialis is a paradoxical muscle. Its origin and innervation are characteristic of an extensor muscle, but it is actually a flexor at the elbow.
The muscle is most visible when the forearm is half pronated, and flexing at the elbow against resistance.
In the distal forearm, the radial artery and nerve are sandwiched between the brachioradialis and the deep flexor muscles.
Origin: proximal aspect of the lateral supracondylar ridge of humerus
Insertion: distal end of the radius, just before the radial styloid process.
Action: Flexes at the elbow. Contributes to supination at the proximal radioulnar joint.
Innervation: Radial nerve.
Blood supply: radial artery
Description, Origin, insertion, action, innervation + blood supply of Extensor Carpi Radialis Longus and Brevis
The extensor carpi radialis muscles are situated on the lateral aspect of the posterior forearm. Due to their position, they are able to produce abduction as well as extension at the wrist.
Origin: The ECRL originates from the lateral supracondylar ridge of the humerus, while the ECRB originates from the lateral epicondyle
Insertion: tendons attach to metacarpal bones II and III
Action: Extends and abducts the wrist
Innervation: Radial nerve
Blood supply: radial artery
Description, Origin, insertion, action, innervation + blood supply of extensor digitorum
The extensor digitorum is the main extensor of the fingers. To test the function of the muscle, the forearm is pronated, and the fingers extended against resistance.
Origin: lateral epicondyle
Insertion: The tendon continues into in the distal part of the forearm, where it splits into four, and inserts into the extensor hood of each finger.
Action: Extension of the digits at the interphalangeal and metacarpophalangeal joints.
Innervation: Radial nerve (deep branch).
Blood supply: radial artery
Which muscles are in each layer of the posterior compartment of the forearm?
superficial layer of the posterior forearm contains seven muscles:
Brachioradialis, extensor carpi radialis longus + brevis, extensor digitorum, Anconeus, extensor carpi ulnaris and extensor digiti minimi
Description, Origin, insertion, action, innervation + blood supply of extensor digiti minimi
The extensor digiti minimi is thought to originate from the extensor digitorum muscle. In some people, these two muscles are fused together. It lies medially to the extensor digitorum.
Origin: lateral epicondyle of the humerus
Insertion: extensor hood of the little finger.
Action: Extends the little finger, and contributes to extension at the wrist.
Innervation: Radial nerve (deep branch).
Blood supply: radial artery
Description, Origin, insertion, action, innervation + blood supply of extensor carpi ulnaris
The extensor carpi ulnaris is located on the medial aspect of the posterior forearm. Due to its position, it is able to produce adduction as well as extension at the wrist.
Origin: lateral epicondyle of the humerus
Insertion: attaches to the base of metacarpal V
Action: Extension and adduction of wrist.
Innervation: Radial nerve (deep branch).
Blood supply: ulnar artery
Description, Origin, insertion, action, innervation + blood supply of anconeus
The anconeus is situated medially and proximally in the extensor compartment of the forearm. It is blended with the fibres of the triceps brachii, and the two muscles can be indistinguishable.
Origin: lateral epicondyle
Insertion: posterior and lateral part of the olecranon
Action: Extends and stabilises the elbow joint. Abducts the ulna during pronation of the forearm.
Innervation: Radial nerve
Blood supply: Profunda brachii artery
Description, Origin, insertion, action, innervation + blood supply of supinator
The supinator lies in the floor of the cubital fossa. It has two heads, which the deep branch of the radial nerve passes between.
Origin: One originates from the lateral epicondyle of the humerus, the other from the posterior surface of the ulna.
Insertion: posterior surface of the radius
Action: Supinates the forearm
Innervation: Radial nerve (deep branch).
Blood supply: ulnar artery
Description, Origin, insertion, action, innervation + blood supply of abductor pollicis longus
The abductor pollicis longus is situated immediately distal to the supinator muscle. In the hand, its tendon contributes to the radial (lateral) border of the anatomical snuffbox.
Origin: interosseous membrane and the adjacent posterior surfaces of the radius and ulna
Insertion: lateral side of the base of metacarpal I.
Action: Abducts the thumb
Innervation: Radial nerve (posterior interosseous branch).
Blood supply: ulnar artery
Description, Origin, insertion, action, innervation + blood supply of extensor pollicis brevis
The extensor pollicis brevis can be found medially and deep to the abductor pollicis longus. In the hand, its tendon contributes to the radial (lateral) border of the anatomical snuffbox
Origin: posterior surface of the radius and interosseous membrane.
Insertion: base of the proximal phalanx of the thumb.
Action: Extends at the metacarpophalangeal and carpometacarpal joints of the thumb.
Innervation: Radial nerve (posterior interosseous branch).
Blood supply: ulnar artery
Description, Origin, insertion, action, innervation + blood supply of extensor pollicis longus
The extensor pollicis longus muscle has a larger muscle belly than the EPB. Its tendon travels medially to the dorsal tubercle at the wrist, using the tubercle as a ‘pulley’ to increase the force exerted.
The tendon of the extensor pollicis longus forms the ulnar (medial) border of the anatomical snuffbox in the hand.
Origin: posterior surface of the ulna and interosseous membrane
Insertion: distal phalanx of the thumb
Action: Extends all joints of the thumb: carpometacarpal, metacarpophalangeal and interphalangeal.
Innervation: Radial nerve (posterior interosseous branch).
Blood supply: ulnar artery
Description, Origin, insertion, action, innervation + blood supply of Extensor Indicis Proprius
This muscle allows the index finger to be independent of the other fingers during extension.
Origin: posterior surface of the ulna and interosseous membrane, distal to the extensor pollicis longus
Insertion: extensor hood of the index finger.
Action: Extends the index finger.
Innervation: Radial nerve (posterior interosseous branch).
Blood supply: ulnar artery
Description, Origin, insertion, action, innervation + blood supply of opponens pollicis
The opponens pollicis is the largest of the thenar muscles, and lies underneath the other two.
Origin: tubercle of the trapezium and the associated flexor retinaculum
Insertion: lateral margin of the first metacarpal.
Action: Opposes the thumb, by medially rotating and flexing the metacarpal on the trapezium.
Innervation: Median nerve (recurrent branch).
Blood supply: Superficial palmar arch
Description, Origin, insertion, action, innervation + blood supply of abductor pollicis brevis
The abductor pollicis brevis forms the anterolateral aspect of the thenar eminence, overlying the opponens pollicis.
Origin: tubercles of the scaphoid and trapezium, and from the associated flexor retinaculum
Insertion: lateral side of proximal phalanx of the thumb.
Action: Abducts the thumb.
Innervation: Median nerve (recurrent branch).
Blood supply: Superficial palmar arch
Description, Origin, insertion, action, innervation + blood supply of flexor pollicis brevis
The flexor pollicis brevis forms the medial aspect of the thenar eminence. It is described as having a superficial and deep part – although the deep component is variable in size.
Origin: tubercle of the trapezium and from the associated flexor retinaculum
Insertion: base of the proximal phalanx of the thumb.
Action: Flexes the metacarpophalangeal joint of the thumb
Innervation: Median nerve (recurrent branch). The deep head is innervated by the deep branch of the ulnar nerve.
Blood supply: Superficial palmar arch
What does a wrist drop indicate?
Wrist drop is a sign of radial nerve injury that has occurred proximal to the elbow.
There are two areas where the radial nerve is at high-risk of damage:
Axilla – can be injured via humeral dislocations or fractures of the proximal humerus.
Radial groove of the humerus – can be injured via a humeral shaft fracture.
The radial nerve innervates all muscles in the extensor compartment of the forearm. In the event of a radial nerve lesion, these muscles are paralysed. The muscles that flex the wrist are innervated by the median nerve, and thus are unaffected. The tone of the flexor muscles (and gravity) produces unopposed flexion at the wrist joint
What are the thenar muscles?
Opponens Pollicis
Abductor Pollicis Brevis
Flexor Pollicis Brevis
What are the hypothenar muscles?
Opponens Digiti Minimi
Abductor Digiti Minimi
Flexor Digiti Minimi Brevis
What are the interossei muscles?
The interossei muscles are located between the metacarpal bones of the hand. They can be divided into two groups – dorsal and palmar.
In addition to their actions of abduction (dorsal interossei) and adduction (palmar interossei) of the fingers, the interossei also assist the lumbricals in flexion at the MCP joints and extension at the IP joints.
Description, Origin, insertion, action, innervation + blood supply of opponens digit minimi
The opponens digit minimi lies deep to the other hypothenar muscles.
Origin: hook of hamate and associated flexor retinaculum
Insertion: medial margin of metacarpal V.
Action: It rotates the metacarpal of the little finger towards the palm, producing opposition.
Innervation: Ulnar nerve.
Blood supply: Deep palmar arch
Description, Origin, insertion, action, innervation + blood supply of abductor digiti minimi
The abductor digiti minimi is the most superficial of the hypothenar muscle group.
Origin: pisiform and the tendon of the flexor carpi ulnaris
Insertion: base of the proximal phalanx of the little finger
Action: Abducts the little finger.
Innervation: Ulnar nerve.
Blood supply: Deep palmar arch
Description, Origin, insertion, action, innervation + blood supply of flexor digiti minimi brevis
The flexor digiti minimi brevis lies laterally to the abductor digiti minimi in the hand.
Origin: hook of hamate and adjacent flexor retinaculum
Insertion: base of the proximal phalanx of the little finger.
Action: Flexes the metacarpophalangeal joint of the little finger.
Innervation: Ulnar nerve.
Blood supply: Deep palmar arch
Description, Origin, insertion, action, innervation + blood supply of the lumbricals
There are four lumbricals in the hand, each associated with a finger. They are very crucial to finger movement, linking the extensor tendons to the flexor tendons.
Denervation of these muscles is the basis for the ulnar claw and hand of benediction.
Origin: Each lumbrical originates from a tendon of the flexor digitorum profundus
Insertion: They pass dorsally and laterally around each finger, and inserts into the extensor hood.
Action: Flexion at the MCP joint and extension at the interphalangeal (IP) joints of each digit.
Innervation: The lateral two lumbricals (of the index and middle fingers) are innervated by the median nerve. The medial two lumbricals (of the little and ring fingers) are innervated by the ulnar nerve.
Blood supply: Superficial and deep palmar arches
Description, Origin, insertion, action, innervation + blood supply of the dorsal interossei
The most superficial of all dorsal muscles, these can be palpated on the dorsum of the hand. There are four dorsal interossei muscles.
Origin: Each interossei originates from the lateral and medial surfaces of the metacarpals.
Insertion: extensor hood and proximal phalanx of each finger.
Action: Abduction of the digits. Assists in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints.
Innervation: Ulnar nerve.
Blood supply: Dorsal metacarpal arteries
Description, Origin, insertion, action, innervation + blood supply of the palmar interossei
These are located anteriorly on the hand. There are three palmar interossei muscles (although some texts describe a fourth muscle at the base of the proximal phalanx of the thumb).
Origin: Each interossei originates from a medial or lateral surface of a metacarpal
Insertion: extensor hood and proximal phalanx of same finger.
Action: Adduction of the digits. Assists in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints.
Innervation: Ulnar nerve.
Blood supply: Palmar metacarpal arteries
Description, Origin, insertion, action, innervation + blood supply of palmaris brevis
The palmaris brevis is a small, thin muscle, found superficially in the subcutaneous tissue of the hypothenar eminence.
Origin: palmar aponeurosis and flexor retinaculum
Insertion: dermis of the skin on the medial margin of the hand.
Action: Wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand, improving grip.
Innervation: Ulnar nerve.
Blood supply: Superficial palmar arch
Description, Origin, insertion, action, innervation + blood supply of adductor pollicis
The adductor pollicis large triangular muscle with two heads. The radial artery passes anteriorly through the space between the two heads, forming the deep palmar arch.
Origin: One head originates from metacarpal III. The other head originates from the capitate and adjacent areas of metacarpals II and III
Insertion: base of the proximal phalanx of the thumb
Action: Adductor of the thumb.
Innervation: Ulnar nerve.
Blood supply: Deep palmar arch.
Description, Origin, insertion, action, innervation + blood supply of the tensor fascia lata
Tensor fasciae lata is a small superficial muscle which lies towards the anterior edge of the iliac crest. It functions to tighten the fascia lata, and so abducts and medially rotates the lower limb.
Origin: iliac crest and descends inferiorly to the superolateral thigh
Insertion: anterior aspect of the iliotibial tract
Action: gluteal muscle that acts as a flexor, abductor, and internal rotator of the hip
Innervation: superior gluteal nerve
Blood supply: Superior gluteal artery.
Description, Origin, insertion, action, innervation + blood supply of gluteus maximus
The gluteus maximus is the largest of the gluteal muscles. It is also the most superficial, producing the shape of the buttocks.
Origin: gluteal (posterior) surface of the ilium, sacrum and coccyx
Insertion: fibres slope across the buttock at a 45 degree angle and insert onto the iliotibial tract and gluteal tuberosity of the femur
Action: It is the main extensor of the thigh, and assists with lateral rotation. However, it is only used when force is required, such as running or climbing
Innervation: Inferior gluteal nerve.
Blood supply: Superior + inferior gluteal artery.
Description, Origin, insertion, action, innervation + blood supply of gluteus medius
The gluteus medius muscle is fan-shaped and lies between to the gluteus maximus and the minimus. It is similar in shape and function to the gluteus minimus.
Origin: gluteal surface of the ilium
Insertion: lateral surface of the greater trochanter.
Action: Abduction and medial rotation of the lower limb. It stabilises the pelvis during locomotion, preventing ‘dropping’ of the pelvis on the contralateral side.
Innervation: Superior gluteal nerve
Blood supply: superior gluteal artery
Description, Origin, insertion, action, innervation + blood supply of The gluteus minimus
The gluteus minimus is the deepest and smallest of the superficial gluteal muscles. It is similar in shape and function to the gluteus medius.
Origin: ilium
Insertion: converges to form a tendon, inserting to the anterior side of the greater trochanter
Action: Abduction and medial rotation of the lower limb. It stabilises the pelvis during locomotion, preventing ‘dropping’ of the pelvis on the contralateral side.
Innervation: Superior gluteal nerve.
Blood supply: superior gluteal artery
Description, Origin, insertion, action, innervation + blood supply of the piriformis
The piriformis muscle is a key landmark in the gluteal region. It is the most superior of the deep muscles
Origin: anterior surface of the sacrum
Insertion: The fibres travel inferiorly and laterally through the greater sciatic foramen to insert onto the greater trochanter of the femur.
Action: Lateral rotation and abduction.
Innervation: Nerve to piriformis.
Blood supply: sup + inferior gluteal artery
Description, Origin, insertion, action, innervation + blood supply of the obturator internus
The obturator internus forms the lateral walls of the pelvic cavity. In some texts, the obturator internus and the gemelli muscles are considered as one muscle – the triceps coxae.
Origin: pubis and ischium at the obturator foramen
Insertion: It travels through the lesser sciatic foramen, and attaches to the greater trochanter of the femur.
Action: Lateral rotation and abduction.
Innervation: Nerve to obturator internus.
Blood supply: obturator artery
Description, Origin, insertion, action, innervation + blood supply of the gemelli
The gemelli are two narrow and triangular muscles. They are separated by the obturator internus tendon.
Origin: The superior gemellus muscle originates from the ischial spine, the inferior from the ischial tuberosity
Insertion: greater trochanter of the femur.
Action: Lateral rotation and abduction.
Innervation: The superior gemellus muscle is innervated by the nerve to obturator internus, the inferior gemellus is innervated by the nerve to quadratus femoris.
Blood supply: inferior gluteal artery
Description, Origin, insertion, action, innervation + blood supply of the quadratus femoris
The quadratus femoris is a flat, square-shaped muscle. It is the most inferior of the deep gluteal muscles, located below the gemelli and obturator internus.
Origin: lateral aspect of the ischial tuberosity
Insertion: quadrate tuberosity on the intertrochanteric crest.
Action: Lateral rotation.
Innervation: Nerve to quadratus femoris.
Blood supply: inferior gluteal + medial circumflex femoral artery
Description, Origin, insertion, action, innervation + blood supply of the iliopsoas
The iliopsoas is comprised of two separate muscles; the psoas major and iliacus.
These muscles arise in the pelvis and pass under the inguinal ligament into the anterior compartment of the thigh – where they form a common tendon.
Unlike many of the anterior thigh muscles, the iliopsoas does not perform extension of the leg at the knee joint
Origin: psoas major originates from the lumbar vertebrae, and the iliacus originates from the iliac fossa of the pelvis
Insertion: lesser trochanter of the femur.
Action: Flexion of the the thigh at the hip joint.
Innervation: The psoas major is innervated by anterior rami of L1-3, while the iliacus is innervated by the femoral nerve.
Blood supply: femoral artery
Description, Origin, insertion, action, innervation + blood supply of the quadriceps femoris
The quadriceps femoris consists of four individual muscles – the three vastus muscles and the rectus femoris. It forms the main bulk of the anterior thigh, and is one of the most powerful muscles in the body. They are all innervated by the femoral nerve.
The four muscles collectively insert onto the patella via the quadriceps tendon. The patella, in turn, is attached to the tibial tuberosity by the patella ligament.
Vastus Lateralis
Proximal attachment: Originates from the greater trochanter and the lateral lip of linea aspera of the femur.
Actions: Extension of the knee joint. It has a secondary function of stabilising the patella.
Vastus Intermedius
Proximal attachment: Originates from the anterior and lateral surfaces of the femoral shaft.
Actions: Extension of the knee joint. It has a secondary function of stabilising the patella.
Vastus Medialis
Proximal attachment: Originates from the intertrochanteric line and medial lip of the linea aspera of the femur.
Actions: Extension of the knee joint. It has a secondary function of stabilising the patella.
Rectus Femoris
Attachments: Originates from the anterior inferior iliac spine and the ilium of the pelvis. It attaches to the patella via the quadriceps femoris tendon.
Actions: Extension of the knee joint and flexion of the hip joint (it is the only muscle of the quadriceps group to cross both the hip and knee joints).
Blood supply: femoral artery
Description, Origin, insertion, action, innervation + blood supply of the sartorius
The sartorius is the longest muscle in the body. It is long and thin, running across the thigh in a inferomedial direction. The sartorius is positioned more superficially than the other muscles in the leg.
Origin: anterior superior iliac spine
Insertion: superior, medial surface of the tibia.
Action: At the hip joint, it is a flexor, abductor and lateral rotator. At the knee joint, it is also a flexor.
Innervation: Femoral nerve.
Blood supply: femoral artery
What is the Trendelenburg sign indicative of?
In a positive sign, pelvic drop will occur on the unsupported leg
If the superior gluteal nerve is damaged, the gluteus medius and the gluteus minimusare paralysed – and the pelvis becomes unsteady.
if the left gluteal muscles are weak, the right side of the pelvis will drop when the patient stands on their left leg (and the right leg is unsupported).
What muscles are in the anterior compartment of the thigh?
Iliopsoas
Quadriceps Femoris
Sartorius
Pectineus
Description, Origin, insertion, action, innervation + blood supply of the pectineus
The pectineus is a flat, quadrangular-shaped muscle which contributes to the floor of the femoral triangle.
Origin: pectineal line of the pubis bone
Insertion: pectineal line on the posterior aspect of the femur, immediately inferior to the lesser trochanter.
Action: Adduction and flexion at the hip joint.
Innervation: Femoral nerve. May also receive a branch from the obturator nerve.
Blood supply: femoral artery
Description, Origin, insertion, action, innervation + blood supply of the adductor magnus
The adductor magnus is the largest muscle in the medial compartment of the thigh.
It is comprised of two parts – an adductor component and a hamstring component.
Adductor – Originates from the inferior rami of the pubis and the rami of ischium, attaches to the linea aspera of the femur.
Hamstring part – Originates from the ischial tuberosity, attaches to the adductor tubercle and medial supracondylar line of the femur.
Action:
Adductor – Adduction and flexion of the thigh
Hamstring – Adduction and extension of the thigh.
Innervation:
Adductor – Obturator nerve (L2-L4)
Hamstring part – Tibial component of the sciatic nerve (L4-S3).
Blood supply: obturator artery
Description, Origin, insertion, action, innervation + blood supply of the adductor longus
The adductor longus is a large, flat muscle. It partially covers the adductor brevis and magnus. The muscle forms the medial border of the femoral triangle.
Origin: pubis bone of the pelvis pubis bone of the pelvis
Insertion: broad distal attachment along the linea aspera of the femur.
Action: Adduction of the thigh.
Innervation: Obturator nerve (L2-L4).
Blood supply: obturator artery
Description, Origin, insertion, action, innervation + blood supply of the adductor brevis
The adductor brevis is a short muscle, lying underneath the adductor longus.
It separates the anterior and posterior branches of the obturator nerve and is an important anatomical landmark within the medial thigh.
Origin: body of pubis and inferior pubic rami.
Insertion: linea aspera on the posterior surface of the femur (proximal to the adductor longus attachment).
Action: Adduction of the thigh.
Innervation: Obturator nerve (L2-L4).
Blood supply: obturator artery
Description, Origin, insertion, action, innervation + blood supply of the obturator externus
The obturator externus is one of the smaller muscles of the medial thigh and it is located superiorly within the compartment.
Origin: membrane of the obturator foramen and adjacent bone
Insertion: It passes under the neck of femur and attaches onto the posterior aspect of the greater trochanter.
Action: Adduction and lateral rotation of the thigh.
Innervation: Obturator nerve (L2-L4).
Blood supply: obturator artery
Description, Origin, insertion, action, innervation + blood supply of the gracilis
The gracilis is the most superficial and medial of the muscles in this compartment. It crosses at both the hip and knee joints.
Origin: inferior rami of the pubis and the body of the pubis
Insertion: It descends down the medial aspect of the thigh and attaches to the medial surface of the tibial shaft.
Action: Adduction of the thigh at the hip and flexion of the leg at the knee.
Innervation: Obturator nerve (L2-L4).
Blood supply: obturator artery
What are the muscles in the medial compartment of the thigh?
gracilis, obturator externus, adductor brevis, adductor longus and adductor magnus.
Description, Origin, insertion, action, innervation + blood supply of the biceps femoris
The biceps femoris has two heads (long head and short head) and is the most lateral of the muscles in the posterior thigh. The common tendon of the two heads can be palpated laterally within the popliteal fossa (posterior knee region).
Origin: The long head originates from the ischial tuberosity of the pelvis. The short head originates from the linea aspera on posterior surface of the femur.
Insertion: heads form a tendon, which inserts into the head of the fibula.
Action: Main action is flexion at the knee. It also extends the thigh at the hip, and laterally rotates at the hip and knee.
Innervation: Long head innervated by the tibial part of the sciatic nerve, whereas the short head is innervated by the common fibular part of the sciatic nerve.
Blood supply: inferior gluteal artery + deep femoral artery
Description, Origin, insertion, action, innervation + blood supply of the semitendinosus
The semitendinosus is a largely tendinous muscle. It is situated on the medial aspect of the posterior thigh and superficial to the semimembranosus.
Origin: ischial tuberosity of the pelvis
Insertion: medial surface of the tibia.
Action: Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint.
Innervation: Tibial part of the sciatic nerve.
Blood supply: inferior gluteal artery + deep femoral artery
Description, Origin, insertion, action, innervation + blood supply of the semimembranosus
The semimembranosus muscle is flat and broad. It is located deep to the semitendinosus on the medial aspect of the posterior thigh.
Origin: ischial tuberosity (more superiorly than the origin of the semitendinosus and biceps femoris)
Insertion: medial tibial condyle.
Action: Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint.
Innervation: Tibial part of the sciatic nerve.
Blood supply: inferior gluteal artery + deep femoral artery
Description, Origin, insertion, action, innervation + blood supply of the tibialis anterior
The tibialis anterior muscle is located alongside the lateral surface of the tibia. It is the strongest dorsiflexor of the foot.
Origin: lateral surface of the tibia
Insertion: medial cuneiform and the base of metatarsal I
Action: Dorsiflexion and inversion of the foot.
Innervation: Deep fibular nerve.
Blood supply: anterior tibial artery
Description, Origin, insertion, action, innervation + blood supply of the extensor digitorum longus
The extensor digitorum longus lies laterally and deep to the tibialis anterior. Its four tendons can be palpated on the dorsal surface of the foot.
Origin: lateral condyle of the tibia and the medial surface of the fibula.
Insertion: The fibres converge into a tendon, which travels onto the dorsal surface of the foot.
The tendon splits into four and each tendon inserts onto a toe.
Action: Extension of the lateral four toes, and dorsiflexion of the foot.
Innervation: Deep fibular nerve.
Blood supply: anterior tibial artery
Description, Origin, insertion, action, innervation + blood supply of the extensor hallucis longus
The extensor hallucis longus is positioned deep to tibialis anterior and extensor digitorum longus. Its tendon emerges from between the two muscles to insert onto the big toe.
Origin: medial surface of the fibular shaft
Insertion: The tendon crosses anterior to the ankle joint and attaches to the base of the distal phalanx of the great toe.
Action: Extension of the great toe and dorsiflexion of the foot.
Innervation: Deep fibular nerve.
Blood supply: anterior tibial artery
Description, Origin, insertion, action, innervation + blood supply of the fibularis tertius
The fibularis tertius muscle is thought to arise from the most distal part of the extensor digitorum longus. It is not present in all individuals.
Origin: with the extensor digitorum longus from the medial surface of the fibula.
Insertion: tendon descends onto the dorsal surface of the foot and attaches to the fifth metatarsal.
Action: Eversion and dorsiflexion of the foot.
Innervation: Deep fibular nerve.
Blood supply: anterior tibial artery
What are the hamstring muscles?
biceps femoris, semitendinosus and semimembranosus
What are the muscles in the anterior compartment of the leg?
Tibialis Anterior
Extensor Digitorum Longus
Extensor Hallucis Longus
Fibularis Tertius
Description, Origin, insertion, action, innervation + blood supply of the peroneus longus
The peroneus longus is the larger and more superficial muscle within the compartment.
Origin: superior and lateral surface of the fibula and the lateral tibial condyle
Insertion: The fibres converge into a tendon, which descends into the foot, posterior to the lateral malleolus.
The tendon crosses under the foot, and attaches to the bones on the medial side, namely the medial cuneiform and base of metatarsal I.
Action: Eversion and plantarflexion of the foot. Also supports the lateral and transverse arches of the foot.
Innervation: Superficial fibular (peroneal) nerve.
Blood supply: fibular artery
Description, Origin, insertion, action, innervation + blood supply of the peroneus brevis
The peroneus brevis muscle is deeper and shorter than the peroneus longus.
Origin: inferolateral surface of the fibular shaft
Insertion: tendon travels posteriorly to the lateral malleolus, passing over the calcaneus and the cuboidal bones.
The tendon then attaches to a tubercle on the 5th metatarsal
Action: Eversion of the foot.
Innervation: Superficial fibular (peroneal) nerve.
Blood supply: fibular artery
Description, Origin, insertion, action, innervation + blood supply of the gastrocnemius
The gastrocnemius is the most superficial of all the muscles in the posterior leg. It has medial and lateral heads and forms the characteristic “calf” shape of the leg.
Origin: The lateral head originates from the lateral femoral condyle. The medial head originates from the medial femoral condyle
Insertion: converges with the soleus muscle to form the calcaneal tendon. This inserts onto the calcaneus
Action: Plantarflexion at the ankle joint and flexion at the knee joint.
Innervation: Tibial nerve.
Blood supply: Medial and lateral sural arteries (branches of the popliteal artery).
Description, Origin, insertion, action, innervation + blood supply of the soleus
The soleus is a flat muscle located underneath the gastrocnemius. It gets its name from its resemblance to a sole – a flat fish.
Origin: soleal line of the tibia and proximal fibula
Insertion: converges with the fibres of the gastrocnemius to form the calcaneal tendon, which inserts onto the calcaneu
Action: Plantarflexion of the foot at the ankle joint.
Innervation: Tibial nerve
Blood supply: Posterior tibial artery
Description, Origin, insertion, action, innervation + blood supply of the plantaris
The plantaris is a small muscle which is absent in approximately 10% of the population
Origin: lateral supracondylar line of the femur.
Insertion: tendon which travels down the leg, between the gastrocnemius and soleus muscles. It blends with the calcaneal tendon and inserts onto the calcaneus.
Action: Contributes to plantarflexion at the ankle joint and flexion at the knee joint.
Innervation: Tibial nerve.
Blood supply: Lateral sural artery (branch of the popliteal artery).
Description, Origin, insertion, action, innervation + blood supply of the popliteus
The popliteus is located behind the knee joint, forming the base of the popliteal fossa.
Origin: lateral condyle of the femur and the lateral meniscus of the knee joint
Insertion: proximal tibia, immediately above the origin of the soleus muscle.
Action: Lateral rotation of the femur relative to the tibia. This ‘unlocks’ the knee joint so that flexion can occur.
Innervation: Tibial nerve
Blood supply: Popliteal artery
Description, Origin, insertion, action, innervation + blood supply of the flexor digitorum longus
The flexor digitorum longus is a thin muscle and is located medially within the posterior leg.
Origin: posterior surface of the tibia
Insertion: plantar surfaces of the lateral four digits
Action: Flexion of the lateral four toes.
Innervation: Tibial nerve
Blood supply: Posterior tibial artery
Description, Origin, insertion, action, innervation + blood supply of the flexor hallucis longus
The flexor hallucis longus muscle is located laterally within the posterior compartment (this is slightly counter-intuitive, as it is the opposite side to the great toe).
Origin: posterior surface of the fibula
Insertion: plantar surface of the phalanx of the great toe
Action: Flexion of the great toe.
Innervation: Tibial nerve
Blood supply: Posterior tibial artery
Description, Origin, insertion, action, innervation + blood supply of the tibialis posterior
The tibialis posterior is the deepest out of the four muscles. It lies between the flexor digitorum longus and the flexor hallucis longus.
Origin: posterior surface and interosseous membrane of the tibia and fibula
Insertion: The tendon enters the foot posterior to the medial malleolus and attaches to the plantar surfaces of the medial tarsal bones.
Action: Inversion and plantarflexion of the foot. It also contributes to the medial arch of the foot.
Innervation: Tibial nerve
Blood supply: Posterior tibial artery
What is a foot drop indicative of?
Footdrop is a clinical sign that refers to an inability to dorsiflex the foot at the ankle joint – resulting in the foot “dropping” under the influence of gravity.
It indicates paralysis or weakness of the muscles in the anterior compartment of the leg, and typically occurs as a consequence of damage to the common fibular nerve (from which the deep fibular nerve arises)
The inability to dorsiflex the foot can interfere with walking – as the affected foot drags along the ground. To circumvent this, the patient can flick the foot outwards while walking – known as an ‘eversion flick‘.
What muscles are in the lateral compartment of the leg?
peroneus longus and brevis
What muscles are in the posterior compartment of the leg?
superficial: gastrocnemius, soleus, plantaris
deep: popliteus, tibialis posterior, flexor hallucis longus and flexor digitorum longus
Description, Origin, insertion, action, innervation + blood supply of the extensor digitorum brevis
The extensor digitorum brevis is a small, thin muscle which lies underneath the long extensor tendons of the foot.
Origin: calcaneus and inferior extensor retinaculum
Insertion: long extensor tendons of toes 2-4.
Action: Extension of the lateral four toes.
Innervation: Deep fibular nerve.
Blood supply: Fibular artery and anterior tibial artery (dorsal pedis artery distally).
Description, Origin, insertion, action, innervation + blood supply of the extensor hallucis brevis
The extensor hallucis brevis is often considered to be the medial part of the extensor digitorum brevis muscle, rather than a separate structure.
Origin: calcaneus and inferior extensor retinaculum
Insertion: base of the proximal phalanx of the great toe
Action: Extension of the great toe.
Innervation: Deep fibular nerve.
Blood supply: Dorsalis pedis artery.
Description, Origin, insertion, action, innervation + blood supply of the abductor hallucis
The abductor hallucis muscle is located on the medial side of the sole, where it contributes to a small soft tissue bulge.
Origin: medial tubercle of the calcaneus, the flexor retinaculum and the plantar aponeurosis
Insertion: medial base of the proximal phalanx of the great toe.
Action: Abduction and flexion of the great toe.
Innervation: Medial plantar nerve.
Blood supply: Medial plantar and plantar metatarsal arteries
Description, Origin, insertion, action, innervation + blood supply of the flexor digitorum brevis
The flexor digitorum brevis muscle is located laterally to the abductor hallucis. It sits in the centre of the sole, sandwiched between the plantar aponeurosis and the tendons of flexor digitorum longus.
Origin: medial tubercle of the calcaneus and the plantar aponeurosis
Insertion: middle phalanges of the lateral four digits.
Action: Flexion of the lateral four toes at the proximal interphalangeal joints.
Innervation: Medial plantar nerve.
Blood supply: Branches of the anterior and posterior tibial arteries.
Description, Origin, insertion, action, innervation + blood supply of the abductor digiti minimi
The abductor digiti minimi muscle is located on the lateral side of the foot. It is homologous with the abductor digiti minimi of the hand.
Origin: medial and lateral tubercles of the calcaneus and the plantar aponeurosis
Insertion: lateral base of the proximal phalanx of the 5th digit.
Action: Abduction and flexion of the little toe.
Innervation: Lateral plantar nerve.
Blood supply: Lateral plantar artery.
Description, Origin, insertion, action, innervation + blood supply of the quadratus plantae
The quadratus plantae is a flat, square-shaped muscle with two heads of origin.
Origin: medial and lateral plantar surface of the calcaneus
Insertion: tendons of flexor digitorum longus.
Action: Assists the flexor digitorum longus in flexion of the lateral four toes
Innervation: Lateral plantar nerve.
Blood supply: Medial and lateral plantar arteries.
Description, Origin, insertion, action, innervation + blood supply of the lumbrical (feet)
There are four lumbrical muscles in the foot. They are each located medial to their respective tendon of the flexor digitorum longus
Origin: tendons of flexor digitorum longus
Insertion: extensor hoods of the lateral four digits
Action: Flexion at the metatarsophalangeal joints and extension at the interphalangeal joints.
Innervation: Medial lumbrical – medial plantar nerve.
Lateral three lumbricals – lateral plantar nerve
Blood supply: Medial and lateral plantar arteries.
Description, Origin, insertion, action, innervation + blood supply of the flexor hallucis brevis
The flexor hallucis brevis muscle is located on the medial side of the foot. It has two heads of origin.
Origin:
Lateral head – originates from the plantar surfaces of the cuboid and lateral cuneiforms
Medial head – originates from the tendon of the posterior tibialis tendon.
Insertion: base of the proximal phalanx of the great toe
Action: Flexion of the great toe at the metatarsophalangeal joint.
Innervation: Medial plantar nerve.
Blood supply: Posterior tibial and fibular arteries.
Description, Origin, insertion, action, innervation + blood supply of the adductor hallucis
The adductor hallucis muscle is located laterally to the flexor hallucis brevis. It consists of an oblique and transverse head.
Origin: Oblique head – originates from the bases of the 2nd, 3rd, and 4th metatarsals.
Transverse head – originates from the plantar ligaments of the metatarsophalangeal joints.
Insertion: lateral aspect of the base of the proximal phalanx of the great toe.
Action: Adduction of the great toe. Supports the transverse arch of the foot.
Innervation: Deep branch of lateral plantar nerve.
Blood supply: Medial plantar artery
Description, Origin, insertion, action, innervation + blood supply of the flexor digiti minimi brevis
The flexor digiti minimi brevis muscle is located on the lateral side of the foot, underneath the metatarsal of the little toe. It resembles the interossei in structure.
Origin: base of the fifth metatarsal
Insertion: base of the proximal phalanx of the fifth digit
Action: Flexion of the little toe at the metatarsophalangeal joint.
Innervation: Superficial branch of lateral plantar nerve.
Blood supply: Branches of the anterior and posterior tibial arteries.
What are the muscles on the plantar aspect of the foot, in layers from superficial to deep?
1st layer (most superficial): Abductor Hallucis, Flexor Digitorum Brevis, Abductor Digiti Minimi
2nd layer: quadratus plantae and the lumbricals.
3rd layer: flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis
4th layer: plantar and dorsal interossei
Description, Origin, insertion, action, innervation + blood supply of the plantar interossei
There are three plantar interossei, which are located between the metatarsals. Each arises from a single metatarsal.
Origin: medial side of metatarsals three to five
Insertion: medial sides of the phalanges of digits three to five
Action: Adduction of the lateral three digits and flexion at the metatarsophalangeal joints
Innervation: Lateral plantar nerve
Blood supply: Lateral plantar artery
Description, Origin, insertion, action, innervation + blood supply of the dorsal interossei
There are four dorsal interossei, which are located between the metatarsals. Each arises from two metatarsals.
Origin: lateral aspect of the metatarsals
Insertion: first muscle attaches to the medial side of the proximal phalanx of the second digit. The second to fourth interossei attach to the lateral sides of the proximal phalanxes of digits two to four.
Action: Abduction of the lateral four digits and flexion at the metatarsophalangeal joints.
Innervation: Lateral plantar nerve.
Blood supply: Dorsalis pedis, dorsal metatarsal, lateral plantar and plantar metatarsal arteries.
Description, Origin, insertion, action, innervation + blood supply of the external oblique
The external oblique is the largest and most superficial flat muscle in the abdominal wall. Its fibres run inferomedially.
Origin: ribs 5-12
Insertion: iliac crest and pubic tubercle.
Action: Contralateral rotation of the torso.
Innervation: Thoracoabdominal nerves (T7-T11) and subcostal nerve (T12).
Blood supply: Lower posterior intercostal arteries, subcostal artery, deep circumflex iliac artery.
Description, Origin, insertion, action, innervation + blood supply of the internal oblique
The internal oblique lies deep to the external oblique. It is smaller and thinner in structure, with its fibres running superomedially (perpendicular to the fibres of the external oblique).
Origin: inguinal ligament, iliac crest and lumbodorsal fascia
Insertion: ribs 10-12.
Action: Bilateral contraction compresses the abdomen, while unilateral contraction ipsilaterally rotates the torso.
Innervation: Thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of the lumbar plexus.
Blood supply: Lower posterior intercostal and subcostal arteries, superior and inferior epigastric arteries, superficial and deep circumflex arteries, posterior lumbar arteries.
Description, Origin, insertion, action, innervation + blood supply of the transversus abdominis
The transversus abdominis is the deepest of the flat muscles, with transversely running fibres. Deep to this muscle is a well-formed layer of fascia, known as the transversalis fascia.
Origin: inguinal ligament, costal cartilages 7-12, the iliac crest and thoracolumbar fascia.
Insertion: conjoint tendon, xiphoid process, linea alba and the pubic crest.
Action: Compression of abdominal contents.
Innervation: Thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of the lumbar plexus.
Blood supply: Lower posterior intercostal and subcostal arteries, superior and inferior epigastric arteries, superficial and deep circumflex arteries, posterior lumbar arteries.
Description, Origin, insertion, action, innervation + blood supply of the rectus abdominis
The rectus abdominis is long, paired muscle, found either side of the midline in the abdominal wall. It is split into two by the linea alba. The lateral borders of the muscles create a surface marking known as the linea semilunaris.
At several places, the muscle is intersected by fibrous strips, known as tendinous intersections. The tendinous intersections and the linea alba give rise to the ‘six pack’ seen in individuals with a well-developed rectus abdominis.
Origin: crest of the pubis bone
Insertion: xiphoid process of the sternum and the costal cartilage of ribs 5-7.
Action: As well as assisting the flat muscles in compressing the abdominal viscera, the rectus abdominis also stabilises the pelvis during walking, and depresses the ribs.
Innervation: Thoracoabdominal nerves (T7-T11).
Blood supply: Inferior epigastric and superior epigastric arteries; contributions from posterior intercostal, subcostal and deep circumflex arteries.
Description, Origin, insertion, action, innervation + blood supply of the Pyramidalis
This is a small triangular muscle, found superficially to the rectus abdominis. It is located inferiorly, with its base on the pubis bone, and the apex of the triangle attached to the linea alba.
Origin: pubic crest and pubic symphysis
Insertion: linea alba
Action: Tenses the linea alba.
Innervation: Subcostal nerve (T12).
Blood supply: Inferior epigastric artery.
Description, Origin, insertion, action, innervation + blood supply of the quadratus lumborum
The quadratus lumborum muscle is located laterally in the posterior abdominal wall. It is a thick muscular sheet which is quadrilateral in shape. The muscle is located posterior to the psoas major.
Origin: iliac crest and iliolumbar ligament
Insertion: The fibres travel superomedially, inserting onto the transverse processes of L1 – L4 and the inferior border of the 12th rib.
Action: Extension and lateral flexion of the vertebral column. It also fixes the 12th rib during inspiration, so that the contraction of diaphragm is more efficient.
Innervation: Anterior rami of T12 – L4 nerves.
Blood supply: Lumbar, median sacral, iliolumbar and subcostal arteries.
Description, Origin, insertion, action, innervation + blood supply of the psoas major
The psoas major is located near the midline of the posterior abdominal wall, immediately lateral to the lumbar vertebrae.
Origin: transverse processes and vertebral bodies of T12 – L5
Insertion: It then moves inferiorly and laterally, running deep to the inguinal ligament, and attaching to the lesser trochanter of the femur.
Action: Flexion of the thigh at the hip and lateral flexion of the vertebral column.
Innervation: Anterior rami of L1 – L3 nerves.
Blood supply: Lumbar branch of iliolumbar artery.
Describe medial plantar nerve entrapment
The medial plantar nerve can become compressed and irritated as it passes deep to the abductor hallucis muscle.
This can cause aching, numbness and paraesthesia on the medial side of the sole of the foot. The muscle can become compressed during repetitive eversion of the foot, which may occur in some sports such as gymnastics.
What are the muscles in the posterior abdominal wall?
the iliacus, psoas major, psoas minor, quadratus lumborum and the diaphragm
Description, Origin, insertion, action, innervation + blood supply of the psoas minor
The psoas minor muscle is only present in 60% of the population. It is located anterior to the psoas major.
Origin: vertebral bodies of T12 and L1
Insertion: ridge on the superior ramus of the pubic bone, known as the pectineal line.
Action: Flexion of the vertebral column.
Innervation: Anterior rami of the L1 spinal nerve.
Blood supply: Lumbar arteries.
Description, Origin, insertion, action, innervation + blood supply of the iliacus
The iliacus muscle is a fan-shaped muscle that is situated inferiorly on the posterior abdominal wall. It combines with the psoas major to form the iliopsoas – the major flexor of the thigh.
Origin: surface of the iliac fossa and anterior inferior iliac spine
Insertion: Its fibres combine with the tendon of the psoas major, inserting into the lesser trochanter of the femur.
Action: Flexion and lateral rotation of the thigh at the hip joint.
Innervation: Femoral nerve (L2 – L4).
Blood supply: Iliolumbar, deep circumflex iliac, obturator, and femoral arteries.
Description, Origin, insertion, action, innervation + blood supply of the puborectalis
The puborectalis is the most important of the levator ani group for maintaining faecal continence.
Origin: posterior surface of the pubis
Insertion: It forms a U-shaped sling around the anal canal, and attaches to the pubis on the contralateral side.
Action: Tonic contraction bends the anal canal anteriorly. This creates the anorectal angle which contributes to faecal continence. It is voluntarily inhibited during defecation.
Innervation: Nerve to levator ani and pudendal nerve.
Blood supply: Inferior gluteal, inferior vesical and pudendal arteries.
Description, Origin, insertion, action, innervation + blood supply of the pubococcygeus
The pubococcygeus forms the bulk of the levator ani complex. It is located between the puborectalis and iliococcygeus within the pelvic floor.
Origin: posterior surface of the pubis.
Insertion: blends with the contralateral muscle in the midline of the pelvic floor.
Action: Stability and support of abdominal and pelvic organs.
Innervation: Nerve to levator ani and branches of the pudendal nerve.
Blood supply: Inferior gluteal, inferior vesical and pudendal arteries.
What are the muscles in the pelvic floor?
Levator ani muscles: pubococcygeus, puborectalis and iliococcygeus.
Coccygeus muscle.
Fascia coverings of the muscles
Description, Origin, insertion, action, innervation + blood supply of the iliococcygeus
The iliococcygeus is a thin muscle which forms the posterolateral part of the levator ani muscle group.
Origin: ischial spines and the posterior tendinous arch of the internal obturator fascia
Insertion: coccyx, perineal body and anococcygeal ligament. It also blends with the fibres of the contralateral muscle in the midline of the pelvic floor.
Action: Elevates the pelvic floor and anorectal canal.
Innervation: Nerve to levator ani and branches of the pudendal nerve.
Blood supply: Inferior gluteal, inferior vesical and pudendal arteries.
Description, Origin, insertion, action, innervation + blood supply of the coccygeus
The coccygeus is a small triangular muscle located posterior to the levator ani muscle group.
Origin: ischial spines
Insertion: inferior end of the sacrum and coccyx.
Action: Supports the pelvic viscera and flexes the coccyx.
Innervation: Anterior rami of S4 and S5.
Blood supply: Inferior vesical, inferior gluteal and pudendal arteries.
What are the accessory muscles of respiration?
Pec major, pec minor, serratus anterior + scalenes
What are the thoracic cage muscles?
Ext, internal + innermost intercostals
Subcostals
Transverse thoracis
Change volume of thoracic cavity during respiration
