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Outline

Every muscle by region and layer. Expand an entry to see its attachments.

Head & face

superficial
Frontalis
O
Galea aponeurotica (epicranial aponeurosis), the tough sheet of tissue over the top of the skull
I
Skin of the eyebrows, blending with orbicularis oculi and the small muscles between the brows (procerus and corrugator)
A
Raise the eyebrows; Wrinkle the forehead horizontally; Pull the scalp forward (working with occipitalis to move the scalp)
N
Facial nerve (CN VII), temporal branch
Open →
Masseter
O
Superficial part: zygomatic process of the maxilla and the anterior two-thirds of the lower border of the zygomatic arch; Deep part: posterior third of the lower border and the inner surface of the zygomatic arch
I
Superficial part: angle of the mandible and the lower half of the outer surface of the ramus; Deep part: upper half of the ramus, up to the coronoid process
A
Elevate the mandible (close the mouth and clench the teeth); Superficial fibres: help protrude the mandible (push the jaw forward)
N
Masseteric nerve, from the mandibular division of the trigeminal nerve (CN V3)
Open →
Occipitalis
O
Superior nuchal line of the occipital bone (outer part); Mastoid process of the temporal bone
I
Galea aponeurotica (epicranial aponeurosis)
A
Pull the scalp backwards
N
Facial nerve (CN VII), posterior auricular branch
Open →
Orbicularis oculi
O
Nasal part of the frontal bone; Frontal process of the maxilla; Medial palpebral ligament (at the inner corner of the eye); Lacrimal bone (lacrimal part)
I
Lateral palpebral raphe (at the outer corner of the eye); Skin and muscles around the orbit, where the orbital fibres form a complete loop
A
Palpebral part: close the eyelids gently, as in blinking and sleep; Orbital part: close the eyelids tightly (squeezing the eyes shut) and pull the eyebrow down; Lacrimal part: help drain tears towards the nose
N
Facial nerve (CN VII), temporal and zygomatic branches
Open →
Orbicularis oris
O
Maxilla (near the incisor teeth); Mandible (near the incisor teeth); Fibres from the surrounding facial muscles, including buccinator, that blend into the lips
I
Skin and mucous membrane of the lips; Modiolus (the knot of muscle fibres at the corner of the mouth)
A
Close the lips; Pucker and protrude the lips, as in kissing, whistling or playing a wind instrument; Press the lips against the teeth
N
Facial nerve (CN VII), buccal branch (the lower lip also receives the marginal mandibular branch)
Open →
Temporalis
O
Temporal fossa (the shallow hollow on the side of the skull, from the temporal lines down); Deep surface of the temporal fascia
I
Coronoid process of the mandible; Front border of the ramus of the mandible (down to the retromolar fossa, behind the last molar)
A
Anterior (vertical) fibres: elevate the mandible (close the mouth); Posterior (horizontal) fibres: retract the mandible (pull the jaw back)
N
Deep temporal nerves, from the mandibular division of the trigeminal nerve (CN V3)
Open →
Zygomaticus
O
Zygomaticus major: outer surface of the zygomatic bone, just in front of the zygomaticotemporal suture; Zygomaticus minor: outer surface of the zygomatic bone, just behind the zygomaticomaxillary suture
I
Zygomaticus major: modiolus at the corner of the mouth, blending with orbicularis oris; Zygomaticus minor: muscle and skin of the upper lip, blending with levator labii superioris
A
Zygomaticus major: draw the corner of the mouth up and out, as in smiling; Zygomaticus minor: lift the upper lip up and out, showing the upper teeth
N
Facial nerve (CN VII), zygomatic and buccal branches
Open →
intermediate
Buccinator
O
Alveolar processes of the maxilla and mandible, next to the molar teeth; Pterygomandibular raphe (a fibrous band at the back of the mouth)
I
Fibres of orbicularis oris at the corner of the mouth
A
Compress the cheek against the teeth, keeping food between the teeth during chewing; Expel air from the mouth, as in blowing or playing a trumpet; Help suckling in infants
N
Facial nerve (CN VII), buccal branch (motor)
Open →
deep
Pterygoids
O
Lateral pterygoid, upper head: infratemporal surface of the greater wing of the sphenoid bone; Lateral pterygoid, lower head: outer surface of the lateral pterygoid plate; Medial pterygoid, deep head: inner surface of the lateral pterygoid plate; Medial pterygoid, superficial head: pyramidal process of the palatine bone and the maxillary tuberosity
I
Lateral pterygoid, upper head: articular disc and capsule of the temporomandibular joint (and the front of the condyle); Lateral pterygoid, lower head: pterygoid fovea on the neck of the mandibular condyle; Medial pterygoid: inner surface of the ramus and angle of the mandible
A
Lateral pterygoid: protrude the mandible and help open the mouth; Medial pterygoid: elevate the mandible (close the mouth) and help protrude it; Both, one side at a time: move the jaw to the opposite side (side-to-side grinding movement)
N
Nerves to the lateral and medial pterygoid, from the mandibular division of the trigeminal nerve (CN V3)
Open →

Neck

superficial
Platysma
O
Fascia covering the upper parts of pectoralis major and deltoid
I
Lower border of the mandible, below the oblique line; Skin and subcutaneous tissue of the lower face; Muscles around the angle of the mouth, blending with orbicularis oris
A
Tenses and wrinkles the skin of the neck; Draws the lower lip and the corners of the mouth down; Assists in depressing the mandible
N
Cervical branch of the facial nerve (CN VII)
Open →
Sternocleidomastoid
O
Sternal head: upper front surface of the manubrium of the sternum; Clavicular head: upper border and front of the medial third of the clavicle
I
Lateral surface of the mastoid process of the temporal bone; Lateral half of the superior nuchal line of the occipital bone
A
One side: rotates the head so the face turns to the opposite side; One side: laterally flexes the neck to the same side; Both sides: flex the neck; Both sides, with the head fixed: lift the sternum as an accessory muscle of breathing
N
Accessory nerve (CN XI) (C2–C3 (sensory/proprioceptive))
Open →
intermediate
Levator scapulae
O
Transverse processes of C1–C2 (atlas and axis); Posterior tubercles of the transverse processes of C3–C4
I
Medial border of the scapula, from the superior angle down to the root of the spine of the scapula
A
Elevates the scapula; Downwardly rotates the scapula (tilts the glenoid cavity down); With the shoulder fixed: laterally flexes the neck and rotates it to the same side
N
Cervical nerves C3–C4, often with a branch of the dorsal scapular nerve (C3–C5)
Open →
Scalenes
O
Anterior scalene: anterior tubercles of the transverse processes of C3–C6; Middle scalene: posterior tubercles of the transverse processes of C2–C7; Posterior scalene: posterior tubercles of the transverse processes of C4–C6
I
Anterior scalene: scalene tubercle and upper surface of the first rib, in front of the subclavian groove; Middle scalene: upper surface of the first rib, behind the subclavian groove; Posterior scalene: outer surface of the second rib
A
One side: laterally flexes the neck to the same side; Both sides: slightly flex the neck; Anterior and middle scalenes: lift the first rib (accessory muscles of breathing); Posterior scalene: lifts the second rib
N
Ventral rami of the cervical spinal nerves (C3–C8)
Open →
Semispinalis capitis
O
Tips of the transverse processes of the upper six or seven thoracic vertebrae; Transverse process of C7 and articular processes of C4–C6
I
Occipital bone between the superior and inferior nuchal lines
A
Both sides: extend the head and help extend the neck; One side: tilts the head to the same side and turns the face slightly to the opposite side
N
Dorsal rami of the cervical spinal nerves, including the greater occipital nerve (Cervical dorsal rami (the greater occipital nerve is from C2))
Open →
Splenius capitis
O
Lower half of the ligamentum nuchae; Spinous processes of C7–T3
I
Mastoid process of the temporal bone; Occipital bone, just below the lateral third of the superior nuchal line
A
Both sides: extend the head and neck; One side: laterally flexes the head and neck to the same side; One side: rotates the head to the same side
N
Posterior (dorsal) rami of the cervical spinal nerves (C3–C4)
Open →
deep
Longus colli
O
Superior oblique part: anterior tubercles of the transverse processes of C3–C5; Inferior oblique part: front of the bodies of T1–T3; Vertical part: front of the bodies of C5–C7 and T1–T3
I
Superior oblique part: anterior tubercle of the atlas (C1); Inferior oblique part: anterior tubercles of the transverse processes of C5–C6; Vertical part: front of the bodies of C2–C4
A
Flexes the neck; Slightly rotates the cervical spine
N
Ventral rami of the cervical spinal nerves (C2–C6)
Open →
Suboccipitals
O
Rectus capitis posterior major: spinous process of the axis (C2); Rectus capitis posterior minor: tubercle on the posterior arch of the atlas (C1); Obliquus capitis inferior: spinous process of the axis (C2); Obliquus capitis superior: transverse process of the atlas (C1)
I
Rectus capitis posterior major: lateral part of the inferior nuchal line of the occipital bone; Rectus capitis posterior minor: medial part of the inferior nuchal line and the bone between it and the foramen magnum; Obliquus capitis inferior: transverse process of the atlas (C1); Obliquus capitis superior: occipital bone between the superior and inferior nuchal lines
A
Rectus capitis posterior major and minor: extend the head; Rectus capitis posterior major and obliquus capitis inferior: rotate the head so the face turns to the same side; Obliquus capitis superior: extends the head and tilts it to the same side
N
Suboccipital nerve (dorsal ramus of C1) (C1)
Open →

Back

superficial
Latissimus dorsi
O
Spinous processes of T7–T12; Thoracolumbar fascia (attaching it to the lumbar and sacral spinous processes); Posterior part of the iliac crest; Lower three or four ribs; Inferior angle of the scapula (a small slip, often present)
I
Floor of the intertubercular (bicipital) groove of the humerus
A
Extends the shoulder; Adducts the shoulder; Medially rotates the shoulder; With the arms fixed overhead: pulls the trunk up towards the arms, as in climbing; Assists extension and lateral flexion of the lumbar spine
N
Thoracodorsal nerve (C6–C8)
Open →
Trapezius
O
External occipital protuberance; Medial third of the superior nuchal line; Ligamentum nuchae; Spinous processes of C7–T12
I
Lateral third of the clavicle; Acromion; Spine of the scapula
A
Upper fibres: elevate and upwardly rotate the scapula; extend and laterally flex the neck; rotate the head to the opposite side; Middle fibres: retract the scapula; Lower fibres: depress and upwardly rotate the scapula
N
Accessory nerve (CN XI) (C3–C4 (sensory/proprioceptive))
Open →
intermediate
Erector spinae
O
Common tendon: medial and lateral crests of the sacrum, spinous processes of the lumbar vertebrae and T11–T12, and the supraspinous ligament; Back part of the inner lip of the iliac crest; Higher parts of each column: the ribs and the transverse processes of the thoracic vertebrae, in overlapping slips
I
Iliocostalis (lateral column): angles of the ribs and posterior tubercles of the transverse processes of C4–C7; Longissimus (intermediate column): transverse processes of the thoracic and cervical vertebrae, the lower ribs, and the mastoid process; Spinalis (medial column): spinous processes of the upper thoracic vertebrae and the axis (C2)
A
Both sides: extend the vertebral column and hold the trunk upright; One side: laterally flex the trunk and neck to the same side; Longissimus capitis: extends the head and turns the face to the same side
N
Posterior (dorsal) rami of the spinal nerves (Segmental, at each level of the spine)
Open →
Rhomboid major
O
Spinous processes of T2–T5; Supraspinous ligament
I
Medial border of the scapula, from the root of the spine of the scapula down to the inferior angle
A
Retracts the scapula (draws it towards the spine); Downwardly rotates the scapula; Holds the scapula against the thoracic wall
N
Dorsal scapular nerve (C5)
Open →
Rhomboid minor
O
Lower part of the ligamentum nuchae; Spinous processes of C7–T1
I
Medial border of the scapula at the level of the root of the spine of the scapula
A
Retracts the scapula (draws it towards the spine); Downwardly rotates the scapula; Holds the scapula against the thoracic wall
N
Dorsal scapular nerve (C4–C5)
Open →
Serratus posterior
O
Superior: lower part of the ligamentum nuchae, spinous processes of C7–T3 and the supraspinous ligament; Inferior: spinous processes of T11–L2 and the supraspinous ligament, through an aponeurosis blended with the thoracolumbar fascia
I
Superior: upper borders of ribs 2–5, just lateral to their angles; Inferior: lower borders of ribs 9–12, just lateral to their angles
A
Superior: elevates ribs 2–5 (assists breathing in); Inferior: draws ribs 9–12 down and back
N
Intercostal nerves (ventral rami of the thoracic spinal nerves) (T2–T5 (superior); T9–T12 (inferior))
Open →
deep
Multifidus
O
Sacral region: back of the sacrum, medial surface of the PSIS, posterior sacroiliac ligaments and the erector spinae aponeurosis; Lumbar region: mammillary processes; Thoracic region: transverse processes; Cervical region: articular processes of C4–C7
I
Spinous processes of the vertebrae two to four levels above the origin
A
Both sides: extend the spine and steady each spinal segment; One side: laterally flexes the spine to the same side; One side: rotates the trunk so the front turns to the opposite side
N
Posterior (dorsal) rami of the spinal nerves (Segmental, at each level of the spine)
Open →
Quadratus lumborum
O
Iliolumbar ligament; Posterior part of the inner lip of the iliac crest
I
Lower border of the 12th rib (medial half); Tips of the transverse processes of L1–L4
A
One side: laterally flexes the lumbar spine to the same side; One side, with the trunk fixed: elevates the pelvis on the same side (hip hitching); Both sides: extend the lumbar spine; Fixes the 12th rib during breathing, giving the diaphragm a stable base
N
Ventral rami of the 12th thoracic and upper lumbar spinal nerves (T12–L4)
Open →

Shoulder

superficial
Deltoid
O
Anterior fibres: anterior border and upper surface of the lateral third of the clavicle; Middle fibres: lateral border of the acromion; Posterior fibres: lower lip of the spine of the scapula
I
Deltoid tuberosity on the lateral side of the humerus shaft
A
All fibres: abduct the shoulder (main abductor after the first 15° or so); Anterior fibres: flex and medially rotate the shoulder; Middle fibres: abduct the shoulder; Posterior fibres: extend and laterally rotate the shoulder; Helps hold the head of the humerus in place when carrying heavy loads
N
Axillary nerve (C5–C6)
Open →
intermediate
Infraspinatus
O
Infraspinous fossa of the scapula
I
Middle facet of the greater tubercle of the humerus
A
Laterally (externally) rotates the arm; Stabilises the glenohumeral (shoulder) joint by holding the head of the humerus in the socket
N
Suprascapular nerve (C5–C6)
Open →
Teres major
O
Posterior surface of the inferior angle of the scapula
I
Medial lip of the intertubercular (bicipital) groove of the humerus
A
Adducts the arm; Medially (internally) rotates the arm; Extends the arm from a flexed position
N
Lower subscapular nerve (C5–C6)
Open →
Teres minor
O
Upper two-thirds of the lateral border of the scapula (posterior surface)
I
Inferior facet of the greater tubercle of the humerus; Posterior surface of the shoulder joint capsule
A
Laterally (externally) rotates the arm; Stabilises the shoulder, stopping the head of the humerus sliding upwards as the arm is abducted
N
Axillary nerve (C5–C6)
Open →
deep
Subscapularis
O
Subscapular fossa (medial two-thirds of the front, or costal, surface of the scapula)
I
Lesser tubercle of the humerus; Front of the shoulder joint capsule
A
Medially (internally) rotates the arm; Adducts the arm; Stabilises the front of the shoulder joint, preventing the head of the humerus moving forwards
N
Upper and lower subscapular nerves (C5–C6)
Open →
Supraspinatus
O
Medial two-thirds of the supraspinous fossa of the scapula
I
Superior facet of the greater tubercle of the humerus; Blends with the shoulder joint capsule
A
Abducts the arm, mainly during the first 15° before the deltoid takes over; Pulls the head of the humerus in towards the glenoid cavity, stabilising the shoulder joint; Stops the head of the humerus slipping downwards
N
Suprascapular nerve (C5–C6)
Open →

Chest

superficial
Pectoralis major
O
Clavicular head: anterior surface of the medial half of the clavicle; Sternocostal head: anterior surface of the sternum and the costal cartilages of the upper six ribs; Sternocostal head: aponeurosis of the external oblique muscle
I
Lateral lip of the intertubercular (bicipital) groove of the humerus
A
Whole muscle: adducts and medially rotates the arm; Clavicular head: flexes the arm; Sternocostal head: extends the arm from a flexed position; horizontally adducts the arm
N
Lateral and medial pectoral nerves (C5–T1 (clavicular head C5–C6; sternocostal head C7–T1))
Open →
intermediate
Serratus anterior
O
Outer surfaces of the upper 8–9 ribs, by a series of finger-like slips
I
Front (costal) surface of the medial border of the scapula, from the superior to the inferior angle
A
Protracts the scapula (pulls it forwards around the chest wall); Upwardly rotates the scapula (lower fibres), helping lift the arm overhead; Holds the scapula flat against the chest wall; Helps lift the ribs in breathing when the shoulder girdle is fixed
N
Long thoracic nerve (C5–C7)
Open →
deep
Pectoralis minor
O
Outer surfaces of ribs 3–5, near the costal cartilages
I
Medial border and upper surface of the coracoid process of the scapula
A
Draws the scapula forwards and downwards (protraction and depression), holding it against the chest wall; Raises the ribs during forced breathing in when the scapula is fixed
N
Medial pectoral nerve (C8–T1)
Open →

Arm

superficial
Anconeus
O
Back of the lateral epicondyle of the humerus (by its own tendon)
I
Lateral side of the olecranon; Upper quarter of the back of the ulna
A
Assists the triceps in extending the elbow; Stabilises the elbow during pronation and supination; Pulls the joint capsule out of the way during elbow extension
N
Radial nerve (nerve to anconeus) (C7–C8)
Open →
Biceps brachii
O
Short head: tip of the coracoid process of the scapula; Long head: supraglenoid tubercle of the scapula (its tendon runs through the shoulder joint and the intertubercular groove)
I
Radial tuberosity; Bicipital aponeurosis into the deep fascia on the medial side of the forearm
A
Supinates the forearm (turns the palm up), most strongly with the elbow bent; Flexes the elbow, most strongly with the forearm supinated; Weakly flexes the shoulder; Long head: helps hold the head of the humerus in the socket; Short head: helps adduct the arm across the body
N
Musculocutaneous nerve (C5–C7)
Open →
Triceps brachii
O
Long head: infraglenoid tubercle of the scapula; Lateral head: back of the humerus, above the radial groove; Medial head: back of the humerus, below the radial groove
I
Olecranon process of the ulna; Back of the elbow joint capsule and the deep fascia of the forearm
A
All heads: extend the elbow; Long head: extends and adducts the arm at the shoulder, and helps stabilise the shoulder joint; Steadies the elbow during fine hand movements, such as writing
N
Radial nerve (C6–C8)
Open →
deep
Brachialis
O
Front of the lower half of the humerus
I
Coronoid process of the ulna; Tuberosity of the ulna
A
Flexes the elbow, whether the palm faces up, down or sideways
N
Musculocutaneous nerve (often also a branch of the radial nerve) (C5–C7)
Open →
Coracobrachialis
O
Tip (apex) of the coracoid process of the scapula, sharing a tendon with the short head of biceps brachii
I
Middle of the medial border of the humerus shaft
A
Flexes the arm at the shoulder (weakly); Adducts the arm at the shoulder (weakly); Helps keep the arm in line during abduction
N
Musculocutaneous nerve (C5–C7)
Open →

Forearm & hand

superficial
Brachioradialis
O
Lateral supracondylar ridge of the humerus
I
Lateral side of the distal radius, just above the radial styloid process
A
Flexes the elbow, most strongly with the forearm in mid-position (thumb up); Helps bring the forearm back to mid-position from full pronation or supination; Steadies the elbow during quick movements, such as hammering
N
Radial nerve (C5–C6)
Open →
Extensor carpi radialis brevis
O
Lateral epicondyle of the humerus (common extensor tendon); Radial collateral ligament of the elbow; Intermuscular septa between it and the neighbouring muscles
I
Back (dorsal) surface of the base of the 3rd metacarpal
A
Extends the wrist; Slightly abducts the wrist (radial deviation)
N
Deep branch of the radial nerve (C6–C7)
Open →
Extensor carpi radialis longus
O
Lower third of the lateral supracondylar ridge of the humerus; Lateral intermuscular septum; A few fibres from the common extensor tendon on the lateral epicondyle
I
Back (dorsal) surface of the base of the 2nd metacarpal, on its thumb side
A
Extends the wrist; Abducts the wrist (radial deviation, tilting the hand towards the thumb); May assist and steady elbow flexion
N
Radial nerve (C6–C7)
Open →
Extensor carpi ulnaris
O
Humeral head: lateral epicondyle of the humerus (common extensor tendon); Ulnar head: posterior border of the ulna (via an aponeurosis shared with neighbouring muscles)
I
Base of the 5th metacarpal, on its little-finger side
A
Extends the wrist; Adducts the wrist (ulnar deviation, tilting the hand towards the little finger)
N
Posterior interosseous nerve (deep branch of the radial nerve) (C7–C8)
Open →
Extensor digitorum
O
Lateral epicondyle of the humerus (common extensor tendon)
I
Extensor expansions (hoods) of the four fingers, reaching the middle and distal phalanges
A
Extends the four fingers, mainly at the metacarpophalangeal (knuckle) joints; Assists wrist extension; Tends to spread the fingers as it extends them
N
Posterior interosseous nerve (deep branch of the radial nerve) (C7–C8)
Open →
Flexor carpi radialis
O
Medial epicondyle of the humerus (common flexor tendon)
I
Front (palmar) surface of the bases of the 2nd and 3rd metacarpals
A
Flexes the wrist; Abducts the wrist (radial deviation, tilting the hand towards the thumb); Weakly assists pronation and elbow flexion
N
Median nerve (C6–C7)
Open →
Flexor carpi ulnaris
O
Humeral head: medial epicondyle of the humerus (common flexor tendon); Ulnar head: inner margin of the olecranon and upper two-thirds of the posterior border of the ulna
I
Pisiform; Hook of the hamate (via the pisohamate ligament); Front of the base of the 5th metacarpal (via the pisometacarpal ligament)
A
Flexes the wrist; Adducts the wrist (ulnar deviation, tilting the hand towards the little finger)
N
Ulnar nerve (C8–T1)
Open →
Hypothenar muscles
O
Pisiform and pisohamate ligament (abductor digiti minimi); Hook of the hamate (flexor digiti minimi brevis and opponens digiti minimi); Flexor retinaculum — all three muscles
I
Little-finger side of the base of the proximal phalanx of the little finger (abductor digiti minimi); Palm side of the base of the proximal phalanx of the little finger (flexor digiti minimi brevis); Inner (medial) border of the 5th metacarpal (opponens digiti minimi)
A
Abductor digiti minimi: abducts the little finger (moves it away from the ring finger) at the knuckle; Flexor digiti minimi brevis: flexes the little finger at the knuckle (metacarpophalangeal joint); Opponens digiti minimi: draws the 5th metacarpal forward and rotates it, cupping the palm and bringing the little finger towards the thumb
N
Deep branch of the ulnar nerve (C8–T1)
Open →
Palmaris longus
O
Medial epicondyle of the humerus (common flexor tendon)
I
Central part of the flexor retinaculum; Palmar aponeurosis (the tough fascia of the palm)
A
Weakly flexes the wrist; Tenses the palmar aponeurosis; May assist thumb abduction
N
Median nerve (C7–C8)
Open →
Pronator teres
O
Humeral head: medial epicondyle of the humerus (common flexor tendon) and the medial supracondylar ridge just above it; Ulnar head: medial side of the coronoid process of the ulna
I
Rough area at the middle of the lateral surface of the shaft of the radius
A
Pronates the forearm (turns the palm to face down); Assists elbow flexion, mainly against strong resistance
N
Median nerve (C6–C7)
Open →
Thenar muscles
O
Flexor retinaculum (transverse carpal ligament) — all three muscles; Scaphoid and trapezium (abductor pollicis brevis); Trapezium (opponens pollicis and the superficial head of flexor pollicis brevis); Trapezoid and capitate (deep head of flexor pollicis brevis, which may be absent)
I
Thumb side of the base of the proximal phalanx of the thumb (abductor pollicis brevis and flexor pollicis brevis); Thumb side of the 1st metacarpal (opponens pollicis)
A
Abductor pollicis brevis: abducts the thumb (lifts it forward, away from the palm); Flexor pollicis brevis: flexes the thumb at the metacarpophalangeal joint; Opponens pollicis: flexes and rotates the 1st metacarpal to bring the thumb across to the fingertips (opposition)
N
Recurrent branch of the median nerve; the deep head of flexor pollicis brevis is often supplied by the deep branch of the ulnar nerve (C8–T1)
Open →
Wrist extensors
O
Common extensor tendon on the lateral epicondyle of the humerus (extensor carpi radialis brevis, extensor digitorum, extensor carpi ulnaris); Lower third of the lateral supracondylar ridge of the humerus (extensor carpi radialis longus); Posterior border of the ulna (extensor carpi ulnaris)
I
Back of the base of the 2nd metacarpal (extensor carpi radialis longus); Back of the base of the 3rd metacarpal (extensor carpi radialis brevis); Base of the 5th metacarpal (extensor carpi ulnaris); Extensor expansions of the four fingers (extensor digitorum)
A
All members: extend the wrist; Extensor carpi radialis longus and brevis: also abduct the wrist (tilt it towards the thumb); Extensor carpi ulnaris: also adducts the wrist (tilts it towards the little finger); Extensor digitorum: extends the four fingers
N
Radial nerve and its deep branch (posterior interosseous nerve) (C6–C8)
Open →
Wrist flexors
O
Common flexor tendon on the medial epicondyle of the humerus (flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis); Ulna: olecranon and posterior border (flexor carpi ulnaris), coronoid process (flexor digitorum superficialis), upper three-quarters of the front and inner shaft (flexor digitorum profundus); Radius: oblique line on the front of the shaft (flexor digitorum superficialis); Interosseous membrane (flexor digitorum profundus)
I
Bases of the 2nd and 3rd metacarpals (flexor carpi radialis); Pisiform, hook of the hamate and base of the 5th metacarpal (flexor carpi ulnaris); Flexor retinaculum and palmar aponeurosis (palmaris longus); Middle phalanges of the four fingers (flexor digitorum superficialis); Distal phalanges of the four fingers (flexor digitorum profundus)
A
All members: flex the wrist; Flexor carpi radialis: also abducts the wrist (bends it towards the thumb); Flexor carpi ulnaris: also adducts the wrist (bends it towards the little finger); Palmaris longus: tenses the palmar aponeurosis; Flexor digitorum superficialis: flexes the fingers at the middle (proximal interphalangeal) and knuckle (metacarpophalangeal) joints; Flexor digitorum profundus: flexes the fingertips (distal interphalangeal joints) and assists the other finger joints
N
Median nerve, except flexor carpi ulnaris and the inner half of flexor digitorum profundus (ulnar nerve) (C6–T1)
Open →
intermediate
Flexor digitorum superficialis
O
Humeroulnar head: medial epicondyle of the humerus (common flexor tendon) and coronoid process of the ulna; Radial head: oblique line on the front of the upper shaft of the radius
I
Sides of the middle phalanges of the four fingers (each tendon splits to let the flexor digitorum profundus tendon pass through)
A
Flexes the fingers at the proximal interphalangeal (middle) joints; Flexes the fingers at the metacarpophalangeal (knuckle) joints; Assists wrist flexion
N
Median nerve (C7–T1)
Open →
deep
Flexor digitorum profundus
O
Upper three-quarters of the front and inner (medial) surfaces of the ulna; Interosseous membrane; Deep fascia of the forearm
I
Front of the bases of the distal phalanges of the four fingers
A
Flexes the fingers at the distal interphalangeal (fingertip) joints; Assists flexion of the middle and knuckle joints of the fingers; Assists wrist flexion
N
Inner half (ring and little fingers): ulnar nerve; outer half (index and middle fingers): anterior interosseous branch of the median nerve (C8–T1)
Open →
Supinator
O
Lateral epicondyle of the humerus; Radial collateral ligament and annular ligament of the elbow; Supinator crest of the ulna
I
Lateral surface of the upper (proximal) third of the shaft of the radius
A
Supinates the forearm (turns the palm to face up), with the elbow bent or straight
N
Deep branch of the radial nerve (posterior interosseous nerve) (C5–C6)
Open →

Trunk

superficial
External oblique
O
External surfaces of ribs 5–12
I
Outer lip of the iliac crest; Linea alba (via its broad aponeurosis); Pubic crest and pubic tubercle; Inguinal ligament (the lower free edge of its aponeurosis), between the ASIS and the pubic tubercle
A
Both sides: flex the trunk and compress the abdomen; One side: side-bend the trunk to the same side; One side: rotate the trunk to the opposite side; Assist forced exhalation
N
Thoracoabdominal nerves and subcostal nerve (T7–T12)
Open →
Rectus abdominis
O
Pubic crest; Pubic symphysis; Pubic tubercle
I
Costal cartilages of ribs 5–7; Xiphoid process of the sternum
A
Flex the trunk (lumbar spine), as in a sit-up or crunch; Compress the abdominal contents; Assist forced exhalation
N
Thoracoabdominal nerves and subcostal nerve (T7–T12)
Open →
intermediate
Intercostals
O
External intercostals: lower border of ribs 1–11; Internal intercostals: upper border of ribs 2–12; Innermost intercostals: inner surfaces of the ribs, deep to the internal intercostals
I
External intercostals: upper border of the rib below (ribs 2–12); Internal intercostals: lower border of the rib above (ribs 1–11); Innermost intercostals: inner surface of the rib below
A
External intercostals: raise the ribs to widen the chest during inhalation; Internal intercostals: lower the ribs during forced exhalation; Innermost intercostals: thought to work with the internal intercostals; All layers: stiffen the spaces between the ribs so they do not suck in or bulge out while breathing
N
Intercostal nerves (T1–T11)
Open →
Internal oblique
O
Thoracolumbar fascia; Anterior two-thirds of the iliac crest; Lateral half of the inguinal ligament
I
Inferior borders of ribs 10–12; Linea alba (via its aponeurosis); Pubic crest and pectineal line (via the conjoint tendon, shared with transversus abdominis)
A
Both sides: flex the trunk and compress the abdomen; One side: side-bend the trunk to the same side; One side: rotate the trunk to the same side; Assist forced exhalation
N
Thoracoabdominal nerves, subcostal nerve, iliohypogastric nerve and ilioinguinal nerve (T7–L1)
Open →
deep
Diaphragm
O
Sternal part: back of the xiphoid process; Costal part: inner surfaces of the lower six costal cartilages and adjacent ribs (ribs 7–12); Lumbar part: right crus from the bodies of L1–L3, left crus from L1–L2, and the arcuate ligaments
I
Central tendon (the flat top of the dome)
A
Contract and flatten downwards to draw air into the lungs (the main muscle of quiet inhalation); Relax and rise back up during quiet exhalation; Help raise pressure inside the abdomen, for example when coughing, lifting or giving birth
N
Phrenic nerve (motor); outer edges also receive sensory fibres from the lower intercostal and subcostal nerves (C3–C5)
Open →
Transversus abdominis
O
Inner surfaces of the costal cartilages of ribs 7–12 (interlocking with the diaphragm); Thoracolumbar fascia; Anterior three-quarters of the inner lip of the iliac crest; Lateral third of the inguinal ligament
I
Xiphoid process; Linea alba (via its aponeurosis); Pubic crest and pectineal line (via the conjoint tendon, shared with internal oblique)
A
Compress the abdominal contents; Assist forced exhalation; Tension the thoracolumbar fascia to help stabilise the lower back
N
Thoracoabdominal nerves, subcostal nerve, iliohypogastric nerve and ilioinguinal nerve (T7–L1)
Open →

Hip

superficial
Gluteus maximus
O
Outer surface of the ilium behind the posterior gluteal line, and the iliac crest just above it; Lower part of the back of the sacrum and the side of the coccyx; Thoracolumbar fascia (aponeurosis of the erector spinae); Sacrotuberous ligament; Gluteal aponeurosis (the fascia covering gluteus medius)
I
Upper fibres and superficial lower fibres: iliotibial tract (IT band) of the fascia lata; Deep lower fibres: gluteal tuberosity of the femur
A
All fibres: extend the hip (for example, standing up from a squat or climbing stairs); All fibres: laterally rotate the hip; Upper fibres: abduct the hip; Lower fibres: adduct the hip; Through the iliotibial tract, helps steady the extended knee; Working from below, steadies the pelvis and trunk on the femur, especially when standing on one leg
N
Inferior gluteal nerve (L5–S2)
Open →
Tensor fasciae latae
O
Front part of the outer lip of the iliac crest; Outer surface of the anterior superior iliac spine (ASIS) and the notch just below it; Deep surface of the fascia lata
I
Between the two layers of the iliotibial tract (IT band), about one-third of the way down the thigh; through the tract it reaches the lateral condyle of the tibia (Gerdy's tubercle)
A
Tenses the fascia lata and iliotibial tract; Flexes the hip; Abducts the hip; Medially rotates the hip; Steadies the pelvis on the femur when standing, and, through the IT band, helps steady the extended knee; Assists lateral rotation of the tibia
N
Superior gluteal nerve (L4–S1)
Open →
intermediate
Gluteus medius
O
Outer surface of the ilium between the iliac crest and posterior gluteal line above and the anterior gluteal line below; Gluteal aponeurosis (its own covering fascia)
I
Oblique ridge on the lateral surface of the greater trochanter of the femur
A
All fibres: abduct the hip; All fibres: keep the pelvis level when standing on one leg (stop the opposite side from dropping); Anterior fibres: flex and medially rotate the hip; Posterior fibres: extend and laterally rotate the hip
N
Superior gluteal nerve (L4–S1)
Open →
deep
Deep hip rotators
O
Piriformis: front surface of the sacrum; Gemellus superior: ischial spine; Obturator internus: inner surface of the obturator membrane and the surrounding bone; Gemellus inferior: upper part of the ischial tuberosity; Quadratus femoris: lateral border of the ischial tuberosity; Obturator externus: outer surface of the obturator membrane and the surrounding pubic and ischial rami
I
Piriformis: upper border of the greater trochanter; Gemelli and obturator internus: medial surface of the greater trochanter, via the shared obturator internus tendon; Quadratus femoris: quadrate tubercle on the intertrochanteric crest; Obturator externus: trochanteric fossa of the femur
A
All members: laterally rotate the hip; All members: steady the head of the femur in the hip socket; Piriformis, gemelli and both obturators: also abduct the flexed hip; Quadratus femoris: also adducts the hip
N
Branches of the sacral plexus (nerve to piriformis, nerve to obturator internus, nerve to quadratus femoris); obturator externus is supplied by the obturator nerve from the lumbar plexus (L3–S2)
Open →
Gemelli
O
Superior gemellus: outer (gluteal) surface of the ischial spine; Inferior gemellus: upper part of the ischial tuberosity, just below the groove for the obturator internus tendon
I
Both: blend with the upper (superior) and lower (inferior) edges of the obturator internus tendon, and so insert with it into the medial surface of the greater trochanter
A
Both: laterally rotate the extended hip; Both: abduct the flexed hip; Both: help steady the head of the femur in the hip socket
N
Superior gemellus: nerve to obturator internus; inferior gemellus: nerve to quadratus femoris (L4–S2 (superior L5–S2; inferior L4–S1))
Open →
Gluteus minimus
O
Outer surface of the ilium between the anterior and inferior gluteal lines; Margin of the greater sciatic notch
I
Anterior border of the greater trochanter of the femur; Expansion to the capsule of the hip joint
A
All fibres: abduct the hip, working with gluteus medius; All fibres: keep the pelvis level when standing on one leg; Anterior fibres: flex and medially rotate the hip; Helps steady the head of the femur in the hip socket
N
Superior gluteal nerve (L4–S1)
Open →
Iliopsoas
O
Psoas major, superficial part: sides of the bodies of T12 and L1–L4 and the discs between them; Psoas major, deep part: transverse processes of L1–L5; Iliacus: upper two-thirds of the iliac fossa (the inner bowl of the ilium), and the area near the anterior inferior iliac spine
I
Lesser trochanter of the femur (psoas major and iliacus share the tendon)
A
Both parts: flex the hip (the strongest hip flexor); Both parts, with the legs fixed: bend the trunk forward on the hip, as in a sit-up; Psoas major, one side: laterally flexes the lumbar spine; Iliacus: acts only on the hip joint
N
Psoas major: anterior rami of the lumbar nerves (lumbar plexus); iliacus: femoral nerve (L1–L4 (psoas major L1–L3; iliacus, via the femoral nerve, L2–L4))
Open →
Obturator externus
O
Bone around the medial side of the obturator foramen (inferior pubic ramus and ramus of the ischium); Medial two-thirds of the outer surface of the obturator membrane
I
Trochanteric fossa of the femur (its tendon runs across the back of the neck of the femur)
A
Laterally rotates the hip; Steadies the hip joint as a postural muscle, and helps hold the head of the femur in the socket during flexion and medial rotation; Helps abduct the flexed hip
N
Obturator nerve (posterior branch) (L3–L4)
Open →
Obturator internus
O
Inner (pelvic) surface of the obturator membrane; Bone around the obturator foramen on the inside of the pelvis (inferior pubic ramus, ischium and the hip bone below and behind the pelvic brim); Obturator fascia, which covers the muscle
I
Front part of the medial surface of the greater trochanter, above the trochanteric fossa (tendon shared with the gemelli)
A
Laterally rotates the extended hip; Abducts the flexed hip; Steadies the head of the femur in the hip socket, including during walking
N
Nerve to obturator internus (L5–S2)
Open →
Piriformis
O
Front (pelvic) surface of the sacrum, by three slips attached around the 2nd to 4th sacral segments; Upper margin of the greater sciatic notch and the ilium near the posterior inferior iliac spine; Capsule of the sacroiliac joint, and sometimes the sacrotuberous ligament
I
Upper border of the greater trochanter of the femur (its tendon joins those of the gemelli and obturator internus)
A
Laterally rotates the extended hip; Abducts the flexed hip; Helps steady the head of the femur in the hip socket; When the hip is flexed to about 90° or more, its rotation action reverses and it helps medially rotate the hip
N
Nerve to piriformis (branch of the sacral plexus) (S1–S2)
Open →
Quadratus femoris
O
Lateral border of the ischial tuberosity
I
Quadrate tubercle on the intertrochanteric crest of the femur, and the quadrate line running down from it
A
Laterally rotates the hip; Adducts the hip; Steadies the head of the femur in the hip socket
N
Nerve to quadratus femoris (L4–S1)
Open →

Thigh

superficial
Adductor longus
O
Body of the pubis, just below the pubic crest and beside the pubic symphysis
I
Middle third of the medial lip of the linea aspera
A
Adducts the hip; Helps flex the hip; Helps laterally rotate the hip
N
Obturator nerve (anterior branch; sometimes the posterior branch) (L2–L4)
Open →
Adductors
O
Body of the pubis, below the pubic crest (adductor longus); Body and inferior ramus of the pubis (adductor brevis, gracilis); Pectineal line of the pubis (pectineus); Inferior pubic ramus, ischial ramus and ischial tuberosity (adductor magnus)
I
Linea aspera on the back of the femur (adductor longus, adductor brevis, adductor magnus); Pectineal line of the femur, below the lesser trochanter (pectineus); Adductor tubercle of the femur (adductor magnus, hamstring part); Upper medial tibia, at the pes anserinus (gracilis)
A
All members: adduct the hip (bring the thigh towards the midline); Pectineus, adductor longus, adductor brevis and gracilis: help flex the hip; Adductor magnus, hamstring part: extends the hip; Gracilis: also helps flex the knee
N
Obturator nerve, except pectineus (femoral nerve) and the hamstring part of adductor magnus (tibial part of the sciatic nerve) (L2–L4)
Open →
Biceps femoris
O
Long head: ischial tuberosity (shared tendon with semitendinosus) and lower part of the sacrotuberous ligament; Short head: outer lip of the linea aspera, the lateral supracondylar line and the lateral intermuscular septum of the femur
I
Outer side of the head of the fibula; Small slip to the lateral condyle of the tibia
A
Both heads: flex the knee; Both heads: laterally rotate the leg when the knee is bent; Long head: extends the hip
N
Long head: tibial part of the sciatic nerve; short head: common fibular part of the sciatic nerve (L5–S1)
Open →
Gracilis
O
Lower half of the pubic symphysis and upper half of the pubic arch (ischiopubic ramus)
I
Upper medial surface of the tibia, at the pes anserinus (between sartorius and semitendinosus)
A
Adducts the hip; Helps flex the hip; Helps flex the knee; Helps medially rotate the leg when the knee is bent
N
Obturator nerve (anterior branch) (L2–L3)
Open →
Hamstrings
O
Ischial tuberosity (sitting bone): biceps femoris long head, semitendinosus and semimembranosus; Linea aspera and lateral supracondylar line of the femur (biceps femoris short head)
I
Head of the fibula (biceps femoris); Upper medial surface of the tibia, at the pes anserinus (semitendinosus); Back of the medial condyle of the tibia (semimembranosus)
A
All members: flex the knee; Semitendinosus, semimembranosus and biceps femoris long head: extend the hip; Semitendinosus and semimembranosus: medially rotate the leg when the knee is bent; Biceps femoris: laterally rotates the leg when the knee is bent
N
Sciatic nerve (tibial part), except biceps femoris short head (common fibular part) (L5–S2)
Open →
Quadriceps
O
Anterior inferior iliac spine and a groove just above the hip socket (acetabulum) (rectus femoris); Greater trochanter, intertrochanteric line and outer lip of the linea aspera of the femur (vastus lateralis); Intertrochanteric line, medial lip of the linea aspera and medial supracondylar line of the femur (vastus medialis); Front and outer surfaces of the upper two-thirds of the femur shaft (vastus intermedius)
I
Patella, by the common quadriceps tendon; Tibial tuberosity, by the patellar ligament (the continuation of the quadriceps tendon below the kneecap)
A
All members: extend (straighten) the knee; Rectus femoris: also flexes the hip; Vastus medialis: helps keep the patella tracking in its groove
N
Femoral nerve (L2–L4)
Open →
Rectus femoris
O
Straight head: anterior inferior iliac spine (AIIS); Reflected head: groove just above the rim of the hip socket (acetabulum)
I
Base of the patella, via the quadriceps tendon; Tibial tuberosity, via the patellar ligament
A
Extends the knee; Flexes the hip
N
Femoral nerve (L2–L4)
Open →
Sartorius
O
Anterior superior iliac spine (ASIS) and the upper part of the notch below it
I
Upper medial surface of the tibia, at the pes anserinus (in front of gracilis and semitendinosus)
A
Flexes the hip; Abducts the hip (weak); Laterally rotates the hip; Flexes the knee; Medially rotates the leg when the knee is bent
N
Femoral nerve (L2–L4)
Open →
Semitendinosus
O
Lower, inner part of the ischial tuberosity (shared tendon with the biceps femoris long head)
I
Upper medial surface of the tibia, at the pes anserinus (with sartorius and gracilis)
A
Flexes the knee; Extends the hip; Medially rotates the leg when the knee is bent; Medially rotates the thigh when the hip is extended
N
Sciatic nerve (tibial part) (L5–S2)
Open →
Vastus lateralis
O
Upper part of the intertrochanteric line of the femur; Front and lower borders of the greater trochanter; Outer border of the gluteal tuberosity; Upper half of the outer lip of the linea aspera
I
Outer border of the patella, via the quadriceps tendon; Tibial tuberosity, via the patellar ligament
A
Extends the knee; Helps stabilise the knee
N
Femoral nerve (L2–L4)
Open →
Vastus medialis
O
Lower, front part of the intertrochanteric line of the femur; The line running down and back from it towards the linea aspera; Medial lip of the linea aspera; Medial supracondylar line of the femur
I
Inner part of the quadriceps tendon and inner border of the patella; Tibial tuberosity, via the patellar ligament
A
Extends the knee; Helps the patella track correctly during movement
N
Femoral nerve (L2–L4)
Open →
intermediate
Pectineus
O
Pectineal line (pecten) of the pubis, between the iliopubic eminence and the pubic tubercle
I
Pectineal line of the femur, running from the lesser trochanter towards the linea aspera
A
Flexes the hip; Adducts the hip; May help rotate the hip (sources disagree on direction)
N
Femoral nerve (sometimes also the accessory obturator nerve) (L2–L3)
Open →
Semimembranosus
O
Upper, outer part of the ischial tuberosity, by a thick flat tendon
I
Back of the medial condyle of the tibia; Medial margin of the tibia; Expansions to the back of the knee joint capsule (oblique popliteal ligament), the fascia over popliteus and the medial collateral ligament
A
Flexes the knee; Extends the hip; Medially rotates the leg when the knee is bent; Medially rotates the thigh when the hip is extended
N
Sciatic nerve (tibial part) (L5–S2)
Open →
deep
Adductor brevis
O
Outer surface of the body and inferior ramus of the pubis
I
Lesser trochanter region and upper part of the linea aspera of the femur
A
Adducts the hip; Helps flex the hip; May help rotate the hip; the direction depends on hip position
N
Obturator nerve (anterior and posterior branches) (L2–L4)
Open →
Adductor magnus
O
Adductor part: inferior ramus of the pubis and ramus of the ischium; Hamstring part: ischial tuberosity
I
Adductor part: rough line from the greater trochanter to the linea aspera, the linea aspera and the medial supracondylar line; Hamstring part: adductor tubercle on the medial condyle of the femur
A
Both parts: adduct the hip; Adductor part: helps flex the hip; Hamstring part: extends the hip; May help rotate the hip; the direction depends on hip position
N
Adductor part: obturator nerve (posterior branch); hamstring part: tibial part of the sciatic nerve (L2–L5)
Open →
Vastus intermedius
O
Front and outer surfaces of the upper two-thirds of the femur shaft; Lower part of the lateral intermuscular septum of the thigh
I
Deep part of the quadriceps tendon, to the patella; Tibial tuberosity, via the patellar ligament
A
Extends the knee
N
Femoral nerve (L2–L4)
Open →

Leg

superficial
Extensor digitorum longus
O
Lateral condyle of the tibia; Upper three-quarters of the anterior surface of the fibula; Upper part of the interosseous membrane; Deep fascia and the septa between it and tibialis anterior and the fibular muscles
I
Middle and distal phalanges of the 2nd–5th toes, via four tendons that spread into an extensor expansion over each toe
A
Extends the 2nd–5th toes (lifts them); Dorsiflexes the ankle (lifts the foot); Fibularis tertius slip (when present): helps evert the foot (turn the sole outwards)
N
Deep fibular (peroneal) nerve (L4–S1)
Open →
Fibularis longus
O
Head of the fibula; Upper two-thirds of the lateral surface of the fibula; Deep fascia and the septa between it and the muscles at the front and back of the leg
I
Lateral side of the base of the first metatarsal; Lateral side of the medial cuneiform
A
Everts the foot (turns the sole outwards); Assists plantarflexion of the ankle (pointing the foot); Supports the transverse and lateral arches of the foot; Steadies the leg over the foot, especially when standing on one leg
N
Superficial fibular (peroneal) nerve (L5–S1)
Open →
Gastrocnemius
O
Medial head: back of the medial condyle of the femur, just above the joint surface; Lateral head: side of the lateral condyle of the femur, just above the joint surface; Back of the knee joint capsule (both heads)
I
Middle of the back of the calcaneus (heel bone), via the calcaneal (Achilles) tendon shared with soleus
A
Plantarflexes the ankle (points the foot and lifts the heel); Flexes the knee; Most active in fast, powerful movements such as running and jumping
N
Tibial nerve (S1–S2)
Open →
Tibialis anterior
O
Lateral condyle and upper half to two-thirds of the lateral surface of the tibia; Adjoining part of the interosseous membrane; Deep surface of the overlying fascia and the septum between it and extensor digitorum longus
I
Medial and under surface of the medial cuneiform; Base of the first metatarsal
A
Dorsiflexes the ankle (lifts the foot and toes towards the shin); Inverts the foot (turns the sole inwards); Supports the inner (medial) arch of the foot; Controls lowering of the foot after the heel strikes the ground in walking
N
Deep fibular (peroneal) nerve (L4–L5)
Open →
intermediate
Fibularis brevis
O
Lower two-thirds of the lateral surface of the fibula; Septa between it and the muscles at the front and back of the leg
I
Tuberosity on the lateral side of the base of the fifth metatarsal
A
Everts the foot (turns the sole outwards); Assists plantarflexion of the ankle (pointing the foot); Steadies the leg over the foot, especially when standing on one leg
N
Superficial fibular (peroneal) nerve (L4–S1)
Open →
Soleus
O
Back of the head of the fibula and the upper third of the back of the fibula shaft; Soleal (popliteal) line and middle third of the medial border of the tibia; Tendinous arch between the tibial and fibular origins
I
Middle of the back of the calcaneus (heel bone), via the calcaneal (Achilles) tendon shared with gastrocnemius
A
Plantarflexes the ankle (points the foot); Steadies the leg over the foot in standing and stops the body falling forward; Helps pump venous blood back up the leg when it contracts (the calf muscle pump)
N
Tibial nerve (S1–S2)
Open →
deep
Extensor hallucis longus
O
Middle half of the anterior surface of the fibula; Adjoining interosseous membrane
I
Base of the distal phalanx of the big toe (dorsal surface); Usually also a slip to the base of the proximal phalanx of the big toe
A
Extends the big toe (lifts it); Assists dorsiflexion of the ankle (lifting the foot)
N
Deep fibular (peroneal) nerve (L4–S1 (mainly L5))
Open →
Flexor digitorum longus
O
Posterior surface of the tibia, from just below the soleal line to about 7–8 cm above its lower end; Fascia covering tibialis posterior
I
Bases of the distal phalanges of the 2nd–5th toes (plantar surface), each tendon passing through a split in the flexor digitorum brevis tendon
A
Flexes the 2nd–5th toes (curls them), helping them grip the ground; Assists plantarflexion of the ankle (pointing the foot); Assists inversion of the foot (turning the sole inwards)
N
Tibial nerve (L5–S1)
Open →
Flexor hallucis longus
O
Lower two-thirds of the posterior surface of the fibula (except the lowest 2.5 cm); Lower part of the interosseous membrane; Septum between it and the fibular muscles, and fascia covering tibialis posterior
I
Base of the distal phalanx of the big toe (plantar surface)
A
Flexes the big toe (bends it down), giving push-off in walking; Assists plantarflexion of the ankle (pointing the foot); Assists inversion of the foot (turning the sole inwards)
N
Tibial nerve (L5–S2)
Open →
Popliteus
O
Groove on the lateral surface of the lateral condyle of the femur (by a short, strong tendon); Oblique popliteal ligament of the knee joint (a few fibres)
I
Posterior surface of the tibia, on the triangular area above the soleal line
A
Leg free (sitting): medially rotates the tibia on the femur; Foot on the ground (standing): laterally rotates the femur on the tibia, unlocking the fully straightened knee; Assists flexion of the knee, especially at the start of bending; Helps stop the femur sliding forward on the tibia when crouching
N
Tibial nerve (L4–S1)
Open →
Tibialis posterior
O
Posterior surface of the interosseous membrane (except its lowest part); Lateral part of the posterior surface of the tibia, from below the soleal line to the junction of the middle and lower thirds; Upper two-thirds of the medial surface of the fibula
I
Tuberosity of the navicular bone (main attachment); Expansions to the sustentaculum tali of the calcaneus, all three cuneiforms, the cuboid and the bases of the 2nd–4th metatarsals
A
Inverts the foot (turns the sole inwards); Assists plantarflexion of the ankle (pointing the foot); Supports the inner (medial) longitudinal arch of the foot; Steadies the lower leg over the foot
N
Tibial nerve (L5–S1)
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Foot

superficial
Plantar intrinsic muscles
O
First layer: medial and lateral processes of the tuberosity of the calcaneus and the plantar aponeurosis (abductor hallucis, flexor digitorum brevis, abductor digiti minimi); Second layer: medial and lateral undersurface of the calcaneus (quadratus plantae); tendons of flexor digitorum longus (lumbricals); Third layer: cuboid and lateral cuneiform (flexor hallucis brevis); bases of the 2nd–4th metatarsals and the plantar ligaments of the toe joints (adductor hallucis); base of the 5th metatarsal (flexor digiti minimi brevis); Fourth layer: sides and bases of the metatarsals (dorsal and plantar interossei)
I
Big-toe muscles (abductor hallucis, flexor hallucis brevis, adductor hallucis): base of the proximal phalanx of the big toe; Little-toe muscles (abductor digiti minimi, flexor digiti minimi brevis): lateral side of the base of the proximal phalanx of the fifth toe; Flexor digitorum brevis: middle phalanges of the 2nd–5th toes; Quadratus plantae: tendon of flexor digitorum longus; Lumbricals and interossei: bases of the proximal phalanges and the extensor expansions of the lesser toes
A
Flexor digitorum brevis and flexor hallucis brevis: bend (flex) the toes; Abductors and dorsal interossei: spread the toes apart; Adductor hallucis and plantar interossei: draw the toes together; Quadratus plantae: straightens the pull of flexor digitorum longus so the toes curl in line; Lumbricals and interossei: bend the toes at the ball of the foot while straightening the toe joints; As a group: help hold up the arches of the foot and stabilise the foot in standing and walking
N
Lateral plantar nerve, except abductor hallucis, flexor digitorum brevis, flexor hallucis brevis and the first lumbrical (medial plantar nerve); both are branches of the tibial nerve
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