Limb musculature and innervation Flashcards
What are examples of different skeletal muscle shapes?
Circular muscle
Pennate muscle: fibres that lie diagonally
Parallel muscle: orientated parallel to the line of action
Fusiform muscle: spindle shaped with a belly larger than insertion and origin
Convergent muscle: fan shaped muscle with wide origins and narrow insertions.
What is a bursa?
A fluid filled sac that provides a cushion between bones and tendons and/or muscles around a joint.
What is present on the bursal side of bone and tendon?
Fibrocartilage called the enthesis
Why is the enthesis rough?
Increase surface area of connection.
Describe flexion and extension
Flexion: Decrease in the anterior angle between the bones of the joint.
Extension: Increase in the anterior angle between the bones of the joint.
Describe abduction and adduction
Abduction: Movement away from the midline of the body.
Adduction: Movement towards the midline of the body.
Describe medial and lateral rotation
Medial rotation: Turning a limb inwardly towards the midline.
Lateral rotation: Turning a limb outwardly away from the midline.
Describe circumduction
Circumduction: Can occur at a ball and socket joint, rotation of the ball circularly in the socket.
Describe pronation and supination
Pronation: An inward twist of the limb.
Supination: An outward twist of the limb.
Describe eversion and inversion
Eversion: Rocking of foot outwards
Inversion: Rocking of foot inwards
Describe plantarflexion and dorsiflexion
Dorsiflexion: flexed foot
Plantaflexion: pointed foot
What muscles permit flexion of the shoulder (3)?
Pectoralis major, coracobrachialis and the deltoid.
Where do shoulder flexors insert?
Humeral shaft proximally
What muscles permit extension of the shoulder (3)?
Triceps brachii, deltoid and latissimus dorsi.
Where do shoulder extensors insert?
Humerus
What abducts the shoulder the first 10-15 degrees?
Supraspinatus
After 10-15 degrees what is the main shoulder abductor?
Deltoid
Where do arm abductors insert into?
Lateral humerus
What are adductors of the arm (4)?
Teres major, triceps brachii, pectoralis major and latissimus dorsi.
What is the major medial rotator at the shoulder?
Subscapularis
What are the lateral rotators of the shoulder?
Teres minor and infraspinatus
Where do the rotator cuff all insert?
Infraspinatus, supraspinatus and teres minor all insert into the greater tuberosity of the humeral head, but the subscapularis inserts into the lesser tuberosity.
How many proximal heads and distal ends does the biceps brachii have?
Two proximal heads, and a distal end.
Where does the distal end of the biceps brachii insert into?
Radial tuberosity
Where are the proximal insertions of the biceps brachii?
Short head from Coracoid process
Long head supraglenoid tubercle (labrum) then passes through the intertubercular groove
How does the biceps brachii stabilise the shoulder joint?
The proximal end tendon is continuous with the glenoid labrum, reducing the risk of anterior dislocation, stabilising the joint.
What muscles provide flexion at the elbow?
Biceps brachii, brachialis and coracobrachialis.
What forearm muscle can provide flexion at elbow?
Brachioradialis
What forearm muscles flex the wrist ?
Flexor carpi ulnaris
Flexor carpi radialis
Flexor digitorum profundus Flexor digitorum superficialis.
Palmaris longus
Where do elbow flexors insert and pass?
Pass anterior to joint and insert into proximal radius and ulna
Where do elbow extensors insert and pass?
Pass posterior to joint and insert into proximal radius and ulna
What are some elbow extensors?
Triceps brachii
Aconeus (lower arm)
What are some wrist extensors?
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor carpi ulnaris
What are some forearm pronators?
Pronator teres
Pronator quadratus
What are some forearm supinators?
Biceps brachii
Supinator
What are the compartments of the forearm?
Superficial anterior compartment
Intermediate anterior compartment
Deep anterior compartment
Superficial posterior compartment
Deep posterior compartment
What are some hip flexors (4)?
Psoas major, iliacus, pectineus and rectus femoris.
Where do hip flexors insert?
Proximal femur
What are some hip extensors?
Gluteus maximus, and hamstring muscles ( biceps femoris, semitendinosus and semimembranosus)
What are the hamstring muscles?
Biceps femoris, semitendinosus and semimembranosus
What are the quadriceps muscles?
Rectus femoris, vastus medius, vastus intermedius and vastus lateralis
Where do hip extensors insert?
Femur, tibia or fibula
What are some hip abductors?
Gluteus medius, gluteus minimus
Where do hip abductors insert?
Greater trochanter
What are some hip adductors?
Adductor magnus, adductor brevis, adductor longus and gracilis.
Where do hip adductors insert?
Linear aspera
What is a medial rotator of the hip?
Adductor longus
What is a lateral rotator of the hip?
Gluteus maximus
What are flexors of the knee?
Hamstrings in posterior compartment (biceps femoris, semimembranosus, semitendinosus)
Where do the hamstrings insert?
Biceps femoris inserts onto the fibula and semitendinosus and semimembranosus insert onto the tibia.
What are extensors of the knee?
Anterior compartment of the thigh, quadriceps. Rectus femoris, vastus medius, vastus intermedius and vastus lateralis.
Where do quadriceps insert?
Quadriceps tendon above the patella.
What dorsiflexes the ankle
Anterior compartment.
What plantarflexes the ankle
Deep and superficial posterior compartment. Gastrocnemius, soleus, plantaris.
What inverts the ankle?
Posterior compartment. Tibialis posterior, and anterior.
What everts the ankle?
Lateral compartment, fibularis and extensor digitorum longus
What plexus innervates the upper limb?
Brachial plexus
What are the roots of the brachial plexus?
Roots are formed by the ventral (anterior) rami of the C5 to T1 spinal nerves.
How many cervical nerves are there?
8
Describe the organisation of the brachial plexus
Roots Trunks Divisions Cords Nerve branches
What do the roots divide into?
Three trunks, superior, middle and inferior
What do the trunks divide into?
Anterior and posterior division
What do the divisions feed into?
Lateral posterior and medial cords
What are the 5 key nerve branches?
Musculocutaneous Axillary Median Ulnar Radial
What are the roots of the musculocutaneous nerve?
C5-C7
What are the roots of the axillary nerve?
C5-C6
What are the roots of the median nerve?
C5/6-T1
What are the roots of the ulnar nerve?
C8-T1
What are the roots of the radial nerve?
C5-T1
What are the nerves from the posterior cord?
Axillary and radial
What nerve comes from the medial cord?
Ulnar
What nerve comes from the lateral cord?
Musculocutaneous
What nerve comes from both lateral and medial cords?
Median nerve
What roots innervate the BBC muscles?
C5-C6
What muscles does the musculataneous nerve innervate?
Anterior compartment of arm
Biceps brachii, brachialis, coracobrachialis
Where is the dermatome of the musculocutaneous nerve?
Skin of lateral forearm
What muscles does the axillary nerve innervate?
The deltoid and the teres minor.
Where is the dermatome of the axillary nerve?
Posterior lateral arm, skin over the lower deltoid.
What muscles does the median nerve innervate?
Innervates the flexor and pronator muscles in the anterior compartment of the forearm.
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor digitorum superficialis
Flexor digitorum profundus (lateral half)
Pronator quadratus
LOAF muscles - flexor pollicis brevis, abductor pollicis brevis, opponens pollicis brevis, radial two lumbercles
What muscles does the radial nerve innervate?
Innervates the triceps brachii and the extensor muscles in the forearm.
Triceps brachii Extensor digitorum Extensor carpi ulnaris Extensor carpi radialis longus Extensor carpi radialis brevis
What muscles does the ulnar nerve innervate?
Innervates the intrinsic muscles of the hand (except LOAF) and two muscles in the forearm; flexor carpi ulnaris and medial half of flexor digitorum profundus
Where is the dermatome of the median nerve?
Palmar surface of the hand, first 3.5 digits.
Where is the dermatome of the radial nerve?
Innervates most of the skin of the posterior side of forearm, the dorsal surface of the lateral side of the palm, and dorsal surface of the lateral three and a half digits.
Where is the dermatome of the ulnar nerve?
The skin of 1.5 of the most medial digits.
Which muscle in the arm is dual innervated?
Flexor digitorum profundus
What root innervates the deep anterior compartment of forearm muscles?
C8 (mainly median nerve, 1/2 of one ulnar)
What roots innervate the superficial anterior compartment of forearm muscles?
C6-C8 (mainly median, one ulnar)
What roots innervate the superficial posterior compartment of forearm muscles?
C5/6 - C7/8 (mainly radial)
What roots innervate the deep posterior compartment of forearm muscles?
(C6)-C7 radial nerve
What root innervates the intrinsic muscles of the hand?
T1
Where is the C5 dermatome?
Upper lateral arm
Where is the C6 dermatome?
Palmar pad of thumb, intermediate anterior arm
Where is the C7 dermatome?
Pad of index finger, most of intermediate palm, middle 3 fingers
Where is the C8 dermatome?
Pad on little finger, skin of medial hand and wrist
Where is the T1 dermatome?
Skin on medial part of elbow
Describe the route of the musculocutaneous nerve
Passes down the flexor compartment of the upper arm. It innervates these muscles.
The nerve continues into the forearm as the lateral cutaneous nerve and provides sensory innervation to the lateral aspect of the forearm.
Describe the route of the axillary nerve
Passes through the quadrangular space, wraps around the surgical neck of the humerus.
Describe the route of the median nerve
Halfway down the arm, the nerve crosses over the brachial artery, and becomes situated medially.
The median nerve enters the anterior compartment of the forearm via the cubital fossa.
The median nerve enters the hand via the carpal tunnel.
Describe the route of the radial nerve
The radial nerve descends down the arm, travelling in a shallow depression within the surface of the humerus, known as the radial groove.
As it descends, the radial nerve wraps around the humerus laterally, and supplies a branch to the medial head of the triceps brachii.
Describe the route of the ulnar nerve
Descends down the medial aspect of the upper arm. At the elbow, it passes posterior to the medial epicondyle of the humerus.
The ulnar nerve is palpable and vulnerable to injury at the medial epicondyle.
In the forearm, the ulnar nerve travels deep to the muscle, alongside the ulna. It enters the hand via the ulnar canal (Guyon’s canal).
What does the lumbosacral plexus innervate?
Lower limb
What are the roots of the lumbosacral plexus?
L2-S5
What are the major nerves of the lumbosacral plexus?
Femoral Obturator Sciatic Tibial Peroneal/Fibular
What are the roots of the femoral nerve?
L2-L4
What are the nerve roots of the quadricep innervation?
Quads (L3-L4)
What are the roots of the obturator nerve?
L2-L4
What are the roots of the sciatic nerve?
L4-S3
What are the roots of the tibial nerve?
L4-S3
What are the roots of the fibular/peroneal nerve?
L4-S2
What muscles does the femoral nerve innervate?
Anterior thigh muscles that flex the hip joint (pectineus, iliacus, sartorius)
Extend the knee (quadriceps femoris: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius)
What muscles does the obturator nerve innervate?
Innervates the muscles of the medial compartment of the thigh
(obturator externus, adductor longus, adductor brevis, adductor magnus and gracilis).
What muscles does the sciatic nerve innervate?
Innervates the muscles of the posterior thigh
(biceps femoris, semimembranosus and semitendinosus)
and the hamstring portion of the adductor magnus (remaining portion of which is supplied by the obturator nerve).
What muscles does the tibial nerve innervate?
The tibial nerve innervates all the muscles in the posterior compartment of the leg.
Deep ( popliteus, flexor hallucis longus, flexor digitorum longus), superficial (gastrocnemius, soleus, plantaris)
What muscles does the fibular nerve innervate?
Innervates the short head of the biceps femoris directly.
Also supplies (via branches) the muscles in the lateral and anterior compartments of the leg.
What leg muscle is dual innervated?
Adductor magnus (obturator and sciatic)
What is the dermatome of the femoral nerve?
Anteromedial thigh (anterior cutaneous branches of the femoral nerve)
Medial side of the leg and foot (saphenous nerve)
What is the dermatome of the obturator nerve?
Skin of the medial thigh.
What is the dermatome of the sciatic nerve?
No direct sensory functions.
What is the dermatome of the tibial nerve?
Innervates the skin of the posterolateral side of the leg, lateral side of the foot, and the sole of the foot.
What is the dermatome of the fibular nerve?
Innervates the skin over the upper lateral and lower posterolateral leg.
Skin of the anterolateral leg, and the dorsum of the foot.
Which lower limb nerve has no sensory function?
Sciatic
What is the L1 dermatome?
Over the inguinal ligament
What is the L2 dermatome?
Lateral upper side of thigh
What is the L3 dermatome?
Lower medial side of thigh/knee
What is the L4 dermatome?
Medial side of the leg and great toe
What is the L5 dermatome?
Lateral leg and digit 2 (middle 3 toes)
What is the S1 dermatome?
Little toe, most of sole, lateral foot
What is the S2 dermatome?
Back of thigh
What is the S3 dermatome?
Skin of gluteal fold
What is the S4/5 dermatome?
Perineal region
Which nerve root for knee jerk patellar tendon and ankle jerk for achilles tendon?
Patellar tenson: L3, L4
Achilles tendon: L5, S1
What are nerve roots for gluteal nerves?
Superior: L4-S2
Inferior L5-S2
What divisions of lumbar plexus are obturator and femoral nerve?
Femoral nerve = posterior division of lumbar plexus
Obturator nerve = anterior division
What nerve root for biceps jerk?
C5
Peripheral nerves from which cords supply extensors of upper limb?
Posterior cord (i.e. gives axillary and radial nerve)
Peripheral nerves derived from which cords supply flexors of upper limb?
Medial (gives ulnar and contributes to median) and lateral cords (gives musculocutaneous and contributes to median)
What are the different trunks of brachial plexus?
Upper trunk C5 and C6
Middle C7
Lower C8 T1
Describe the course of the femoral nerve
Through the psoas major, femoral triangle, below the inguinal ligament it splits into the posterior and anterior divisions.
.
Describe the course of the obturator nerve
Descends through the fibres of the psoas major
The obturator nerve enters the medial thigh via the obturator canal. It then divides into anterior and posterior branches
Describe the course of the sciatic nerve
It leaves the pelvis via greater sciatic foramen.
The nerve moves through the gluteal region to posterior thigh
When the sciatic nerve reaches the apex of the popliteal fossa, it terminates by bifurcating into the tibial and common peroneal nerves.
Describe the course of the tibial nerve
Arises at the apex of the popliteal fossa.
It travels through the popliteal fossa, its course down the leg, posterior to the tibia.
At the foot, the nerve passes through a structure known as the tarsal tunnel.
Describe the course of the common fibular/peroneal nerve
Arises at the popliteal fossa,
The common fibular nerve follows the medial border of the biceps femoris.
Enters the lateral compartment of the leg and wraps around the neck of the fibula.
Here, the common fibular nerve terminates by dividing into the superficial fibular and deep fibular nerves.
Why may the sciatic nerve be classed as two nerves? Which two?
The sciatic nerve can be described as two individual nerves bundled together in the same connective tissue sheath – the tibial and common peroneal nerves
The main spinal nerve root which innervates skin on the lateral side of the foot and heel
S1
What nerve innervates muscles of the thenar eminence?
Median
What roots give dermatome of medial arm?
Lower trunk (C8, T1) of the brachial plexus
The anterior division of the brachial plexus supplies which muscles?
Flexors
Which nerve root contribute to the middle trunk?
C7
The median nerve receives contributions from which cords?
Lateral and medial
Which nerve passes through the quadrangular space?
Axillary
Does the sciatic nerve have some sensory function?
Yes - indirect
What bone promince does the common peroneal nerve lie near to?
lies close to the head of the fibula
What supplies the flexor muscles of the foot?
Tibial
What is the armpit dermatome root?
T2
What is the flexor/extensor of the leg meaning?
Probably dorsiflexion/plantarflexion thigh is upper leg
What nerves innervate the palmar muscle groups of the hand?
Median and ulnar
The action of sartorius is …
Abduction, flexion of the hip, flexion of the knee, lateral rotation of the hip
Give the main motor action of each upper limb root
C5 - deltoid C6 - wrist extensors and biceps C7 - triceps C8 - flexion of fingers (flexor digitorum) T1 - intrinsic hand muscles
Give the main motor action of each lower limb root
L1 - innervates the abdominal internal obliques via the ilioinguinal nerve
L2 - hip flexion
L3 - knee extension
L4 - ankle dorsiflexion
L5 innervates ankle dorsiflexion muscles, big toe extension
S1 mainly plantar flexion muscles
Radial nerve injury
Hand drop, loss of wrist extensors
Medial nerve injury
Hand of benediction
Ulna nerve injury
Claw hand
Thenar eminence muscles
Flexor pollicis brevis, abductor pollicis brevis, adductor pollicis brevis, opponens pollicis brevis
Hypothenar eminence muscles
Abductor digiti minimi, flexor digiti minimi, opponens digiti minimi
Action of interossei muscles
Dorsal - abduction fingers
Palmar - adduction of fingers
Action of lumbricals
Flexion of MCP joint (L shape) and extension of interphalangeal joint
Flexor digitorum profundus action
Flex of distal phalange
Flexor digitorum superficialis action
Flex of intermediate phalange
Medial and lateral borders of the anatomical snuffbox?
Medial - extensor pollicis longus
Lateral - extensor pollicis brevis
Where do forearm extensors and flexors originate from?
Medial epicondyle - flexors
Lateral epicondye - extensors
Serratus anterior innervated by
Long thoracic nerve
Lesion of long thoracic nerve leads to?
Winged scapula as loss of action of serratus anterior
Superficial forearm
Radial to ulnar Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris
Intermediate forearm
Flexor digitorum superficialis
Deep forearm
Flexor digitorum profundus
Pronator quadratus
Flexor pollicis longus
Supinator
Where do the gluteal nerves arise from (relation to a muscle)?
Above and below the piriformus
Piriformus action
Lateral rotation
Superior inferior gluteal nerve innervate
Superior medius and minimus, inferior maximus
Adductor magnus insert
Full length of linea aspera and adductor tubercle
Medial rotators of the hip
Adductor longus and tensor faschiae latae
Lateral rotators of the hip
Gluteus maximus and piriformis
Fractured neck of the femur leads to
Profound lateral rotation of femoral shaft due to powerful gluteus maximus and psoas major
Semitendionsis and semimembranosis insert
Medial tibia
Biceps femoris inserts
Fibula
Where does the patella ligament insert?
Tibial tuberosity
Posterior superficial compartment of the leg muscles and action
Plantar flexion
Gastrocnemius
Soleus
Plantaris
Posterior deep compartment of leg muscles and action
Toe flexion / plantar flexion Flexor hallucis longus Flexor digitorum longus Tibialis posterior (also inversion)
Anterior compartment of the leg muscles and action
Dorsiflexion and toe extension Tibialis anterior (also inversion) Extensor hallucis longus Extensor digitorum longus
Anterior compartment of leg innervation
Deep peroneal /fibula
Lateral compartment of the leg muscles and action
Eversion
Fibularis longus
Fibularis brevis
Fibularis tertius
How does femoral nerve terminate
As sensory saphenous nerve - anteromedial sensory innervation
