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Shoulder and Upper Limb Muscle Attachment A to Z

Shoulder and Upper Limb Muscle Attachment A to Z/The upper extremity or arm is a functional unit of the upper body. It consists of three sections, the upper arm, forearm, and hand. It extends from the shoulder joint to the fingers and contains 30 bones. It also consists of many nerves, blood vessels (arteries and veins), and muscles. The nerves of the arm are supplied by one of the two major nerve plexus of the human body, the brachial plexus.

Shoulder and Upper Limb Muscle Attachment A to Z

Shoulder and Upper Limb Bones

The 126 named bones of the Appendicular Skeleton (all bones are paired):

Shoulder Girdle:
- Clavicle
- Scapula
Arm or upper extremity
- Humerus
- Radius
- Ulna
Wrist or Carpal Bones
- Scaphoid
- Lunate
- Triquetrum
- Pisiform
- Trapezium
- Trapezoid
- Capitate
- Hamate
Hand
- Metacarpals x5
- Phalanx x14
Pelvic Girdle
- Ilium
- Ischium
- Pubis
Leg or lower extremity
- Femur
- Tibia
- Fibula
Tarsal bones (midfoot and the hindfoot)
- Talas
- Calcaneus
- Cuboid
- Medial, intermediate, and lateral cuneiform
- Navicular
Foot
- Metatarsals x5
- Phalanx x14

There are also various sesamoid bones not included in the list such as the largest of the sesamoid bones the patella that provides protection for the knee joint and attachments for the ligaments that allow for the extension of the knee.

Shoulder and Upper Limb Muscle Attachment

Anterior Axioappendicular Muscles (Thoracoappendicular Muscles)[rx]

Pectoralis major

Function: flexion, adduction, medial rotation of the humerus.
Origin: clavicular head: medial clavicle anteriorly, sternocostal head: anterior sternum and costal cartilages of ribs 1 to 6 as well as external oblique aponeurosis
Insertion: the lateral edge of the intertrabecular groove of the humerus
Innervation: medial pectoral nerve (C8, T1) lateral pectoral nerve (C5, C6, C7) of brachial plexus

Pectoralis minor

Function: Depression of the shoulder, protraction of the scapula
Origin: Third, fourth, fifth ribs close to their respective costal cartilages
Insertion: Coracoid process
Innervation: Medial pectoral nerve (C8, T1)

Subclavius

Function: Depression and stabilization of the clavicle
Origin: First rib medially
Insertion: Middle of the clavicle, inferiorly
Innervation: Nerve to subclavius (C5, C6)

Serratus anterior

Function: Protraction of scapula, rotation of the scapula
Origin: Lateral first to the eighth rib
Insertion: anterior scapula, medially
Innervation: long thoracic nerve (C5, C6, C7)

Posterior Axioappendicular Muscles

Superficial layer

Latissimus dorsi

Function: Adduction, medial rotation, an extension of humerus
Origin: Spinous processes of seventh to 12th thoracic vertebrae, iliac crest, thoracolumbar fascia, and inferior third and fourth rib
Insertion: Intertubercular groove of the humerus
Innervation: Thoracodorsal nerve (C5,C6,C7)

Trapezius

Function: Elevation, depression, and retraction of the scapula, rotation of glenoid cavity
Origin: Superior nuchal line, nuchal ligament, occipital protuberance, spinous processes of C7- T12
Insertion: Spine of scapula, acromion, and lateral clavicle
Innervation: CN XI

Deep Layer

Levator scapulae

Function: Adduction, medial rotation, an extension of humerus
Origin: Transverse processes of C1 through C4 vertebrae
Insertion: Scapula at its medial border
Innervation: Thoracodorsal nerve (C5, C6, C7)

Rhomboid major

Function: Retraction of scapula and depression of glenoid cavity
Origin: Spinous processes of T2 through T5 vertebrae
Insertion: Inferior aspect of medial scapula
Innervation: Dorsal scapular nerve (C4, C5)

Rhomboid minor

Function: Retraction of scapula and depression of glenoid cavity
Origin: Nuchal ligament as well as spines of C7 and T1 vertebrae
Insertion: Superior aspect of medial scapula
Innervation: Dorsal scapular nerve (C4, C5)

Scapulohumeral (Intrinsic Shoulder Muscles)

Deltoid

Function: Anterior part: flexion and medial rotation of the arm, middle part: the abduction of arm, posterior part: extension and lateral rotation of the arm
Origin: Lateral clavicle, acromion and scapular spine
Insertion: Deltoid tuberosity
Innervation: Axillary nerve (C5, C6)

Teres major

Function: Adduction and medial rotation of the arm
Origin: Posterior surface of scapula at its inferior angle
Insertion: Intertubercular groove on its medial aspect
Innervation: Lower scapular nerve (C5, C6)

Supraspinatus

Function: Initiation of arm abduction
Origin: Posterior scapula, superior to the scapular spine
Insertion: Superior aspect of the greater tubercle
Innervation: Suprascapular nerve (C5, C6)
Part of rotator cuff muscles

Infraspinatus

Function: Lateral rotation of the arm
Origin: Posterior scapula, inferior to the scapular spine
Insertion: Greater tubercle of the humerus, between the supraspinatus and teres minor insertion
Innervation: Suprascapular nerve (C5, C6)
Part of rotator cuff muscles

Teres minor

Function: Lateral rotation of the arm
Origin: Posterior surface of scapula at its inferior angle
Insertion: Inferior aspect of the greater tubercle
Innervation: Axillary nerve (C5, C6)
Part of rotator cuff muscles

Subscapularis

Function: Adduction and medial rotation of the arm
Origin: Anterior aspect of scapula
Insertion: Lesser tubercle of humerus
Innervation: Subscapular nerves (C5, C6, C7)
Part of rotator cuff muscles

*Rotator cuff muscles: supraspinatus, infraspinatus, teres minor, subscapularis

Muscles of Anterior Compartment of Arm (Flexors of Arm)

Biceps brachii

Function: Major flexion of forearm, supination of the forearm, resists dislocation of the shoulder
Origin: Short head originates from the coracoid process. The long head is from the supraglenoid tubercle of the scapula
Insertion: Radial tuberosity and forearm fascia (as bicipital aponeurosis)
Innervation: Musculocutaneous nerve (C5, C6)

Brachialis

Function: Flexion of forearm
Origin: Distal anterior humerus
Insertion: Coronoid process and ulnar tuberosity
Innervation: musculocutaneous nerve (C5, C6, C7 small contribution)

Coracobrachialis

Function: Flexion and adduction of the arm
Origin: Coracoid process
Insertion: Middle of the humerus, on its medial aspect
Innervation: Musculocutaneous nerve (C5, C6, C7)

Muscles of Posterior Compartment of Arm (Extensors of Arm)

Triceps brachii

Function: Major extensor of the forearm, resists dislocation of the shoulder
Origin: Lateral head: above the radial groove, medial head: below the radial groove, long head: infraglenoid tubercle of the scapula
Insertion: Olecranon process of ulna and forearm fascia
Innervation: Radial nerve (C6,C7,C8)

Anconeus

Function: Extension of the forearm, stabilization of elbow joint
Origin: Lateral epicondyle of humerus
Insertion: Olecranon process and posterior ulna
Innervation: Radial nerve (C7, C8, T1)

Muscles of Anterior Compartment of Forearm (Flexors of Forearm)

Superficial layer

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Pronator teres

Function: Pronation of radio-ulnar joint
Origin: Coronoid process and medial epicondyle of humerus
Insertion: Lateral surface of the radius
Innervation: Median nerve (C6, C7)

Flexor carpi radialis

Function: Flexion and adduction at the wrist
Origin: Medial epicondyle of humerus
Insertion: Base of the second metacarpal
Innervation: Median nerve (C6, C7)

Palmaris longus

Function: Flexion at the wrist, tensing of the palmar aponeurosis
Origin: Medial epicondyle of humerus
Insertion: Flexor retinaculum
Innervation: Median nerve (C7, C8)

Flexor carpi ulnaris

Function: Flexion and adduction at the wrist
Origin: Medial epicondyle of humerus and olecranon
Insertion: Pisiform, the hook of hamate and fifth metacarpal
Innervation: Median nerve (C7, C8)

Intermediate Layer

Flexor digitorum superficialis

Function: Flexion of the proximal interphalangeal joint of the second, third, fourth, and fifth fingers. Also has a weaker flexion action on the metacarpophalangeal joints of the same fingers
Origin: Medial epicondyle, coronoid process, and anterior radius
Insertion: Second, third, fourth, and fifth middle phalanges
Innervation: Median nerve (C7, C8, T1)

Deep Layer

Flexor digitorum profundus

Function: Flexion of the distal interphalangeal joint of the second, third, fourth, and fifth finger
Origin: Medial and the anterior surface of the proximal ulna and interosseous membrane
Insertion: Second, third, fourth, and fifth distal phalanges
Innervation: Ulnar nerve (C8, T1) for the medial part, anterior interosseous nerve (C8, T1) for the lateral

Flexor pollicis longus

Function: Flexion of the interphalangeal joint of the thumb
Origin: Anterior aspect of radius as well as interosseous membrane
Insertion: Base of distal phalanx of thumb
Innervation: Anterior interosseous nerve (C7, C8)

Pronator quadratus

Function: Pronator of the forearm
Origin: Anterior aspect of distal ulna
Insertion: Anterior aspect of the distal radius
Innervation: Anterior interosseous nerve (C7, C8)

Brachioradialis

Function: Weak flexor of the forearm
Origin: Proximal supracondylar ridge on the humerus
Insertion: Lateral surface of the distal end of radius
Innervation: Radial nerve (C5, C6, C7)

Muscles of Posterior Compartment of Forearm

Superficial

Extensor carpi radialis longus

Function: Extension and abduction of the wrist
Origin: Proximal supracondylar ridge on the humerus
Insertion: Dorsal base of the second metacarpal
Innervation: Radial nerve (C6, C7)

Extensor carpi radialis brevis

Function: Extension and abduction of the wrist
Origin: Lateral epicondyle of humerus
Insertion: Dorsal base of the third metacarpal
Innervation: Deep branch of the radial nerve (C7, C8)

Extensor digitorum

Function: Extension of the proximal interphalangeal joint of the second, third, fourth, and fifth fingers. Also has a weaker extension action on the metacarpophalangeal joints of the same fingers
Origin: Lateral epicondyle of humerus
Insertion: Extensor expansions on the dorsal aspect of second, third, fourth, and fifth middle and distal phalanges
Innervation: Posterior interosseous nerve (C7, C8)

Extensor digiti minimi

Function: Extension of the little finger at the metacarpophalangeal joint and interphalangeal joint
Origin: Lateral epicondyle of humerus
Insertion: Extensor expansion on the dorsal aspect of the fifth phalanx
Innervation: Posterior interosseous nerve (C7, C8)

Extensor carpi ulnaris

Function: Extension and adduction of the wrist
Origin: Lateral epicondyle of the humerus and posterior ulna
Insertion: Fifth metacarpal base
Innervation: Posterior interosseous nerve (C7, C8)

Deep Layer

Extensor indices

Function: Extension of the index finger
Origin: Dorsal surface of the distal ulna and interosseous membrane
Insertion: Extensor expansion of the second finger
Innervation: Posterior interosseous nerve (C7, C8)

Supinator

Function: Supination of the forearm
Origin: Lateral epicondyle and supinator crest of the ulna
Insertion: Lateral surface of radius
Innervation: Deep branch of the radial nerve (C7, C8)

Abductor policies longus

Function: Abduction of the thumb by acting on the carpometacarpal joint and the metacarpophalangeal joint
Origin: Dorsal aspects of the proximal radius, ulna, and interosseous membrane
Insertion: Base of the first metacarpal
Innervation: Posterior interosseous nerve (C7, C8)

Extensor pollicus longus

Function: Extension of the thumb by acting on the carpometacarpal joint, the metacarpophalangeal joint, and the interphalangeal joint.
Origin: Dorsal aspects of the middle ulna and interosseous membrane
Insertion: Distal phalanx of 1st finger
Innervation: Posterior interosseous nerve (C7, C8)

Extensor pollicus brevis

Function: Extension of the thumb by acting on the carpometacarpal joint and the metacarpophalangeal joint
Origin: Dorsal aspects of middle radius and interosseous membrane
Insertion: Distal phalanx of 1st finger
innervation: Posterior interosseous nerve (C7, C8)

Intrinsic Muscles of Hand

Thenar muscles

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Opponents policies

Function: Opposition of the thumb
Origin: Flexor retinaculum and tubercle of trapezium
Insertion: Lateral aspect of the first metacarpal
Innervation: Recurrent branch of the median nerve (C8, T1)

Abductor policies Brevis

Function: Abduction of the thumb at the metacarpophalangeal joint
Origin: Flexor retinaculum and tubercle of the scaphoid
Insertion: Lateral aspect of proximal phalanx of the first finger
Innervation: Recurrent branch of the median nerve (C8, T1)

Flexor pollicus brevis

Function: Flexion of the thumb at the metacarpophalangeal joint
Origin: Flexor retinaculum and tubercle of trapezium
Insertion: Lateral aspect of proximal phalanx of the first finger
Innervation: Recurrent branch of the median nerve (C8, T1)

Adductor Compartment

Adductor policies

Function: Adduction of the thumb
Origin: Second, third metacarpal, and capitate
Insertion: Proximal phalanx and extensor expansion of 1st finger
Innervation: Deep branch of the ulnar nerve (C8, T1)

Hypothenar Muscles

Abductor digiti minimi

Function: Abduction of the little finger at the metacarpophalangeal joint
Origin: Pisiform
Insertion: Medial aspect of proximal phalanx of the fifth finger
Innervation: Deep branch of the ulnar nerve (C8, T1)

Flexor digiti minimi brevis

Function: Flexion of the little finger at the metacarpophalangeal joint
Origin: Flexor retinaculum and hook of hamate
Insertion: Medial aspect of proximal phalanx of the fifth finger
Innervation: Deep branch of the ulnar nerve (C8, T1)

Opponents digit minimi

Function: Opposition of the little finger
Origin: Flexor retinaculum and hook of hamate
Insertion: Medial aspect of the fifth metacarpal
Innervation: Deep branch of the ulnar nerve (C8, T1)

Short Muscles

Lumbricals

Function: Flexion of the metacarpophalangeal joints with the extension of the interphalangeal joints
Origin: Arise from tendons of flexor digitorum profundus. First 2 are unipennate, and the third and fourth are bipennate
Insertion: Extensor expansions of the second, third, fourth, and fifth finger
Innervation: Median nerve (C8, T1) for the lateral 2 lumbricals, deep branch of the ulnar nerve (C8, T1) for the medial 2 lumbricals

Dorsal interossei

Function: Abduction of the second, third, and fourth finger away from the axial line
Origin: Adjacent metacarpals
Insertion: Extensor expansions and proximal phalanges of the second, third, and fourth fingers
Innervation: Deep branch of the ulnar nerve (C8, T1)

Palmar interossei

Function: Adduction of the second, third, and fourth finger towards the axial line
Origin: Palmar surfaces of second, fourth, and fifth metacarpals
Insertion: Extensor expansions and proximal phalanges of the second, fourth, and fifth fingers
Innervation: Deep branch of ulnar nerve (C8, T1)

In closing, here are a few specific wrist pathologies with suggested imaging considerations:

Trauma, including suspected distal radius and ulna fractures – Start with plain films and consider further characterize with CT if the fracture is complex. Follow up, and post-surgical imaging can be accomplished with plain film and limited CT as needed. If the patient remains symptomatic despite conservative treatment, repeat radiographs in 10 to 14 days can help to assess for signs of osseous remodeling. Alternatively, a rapid MRI protocol (limited exam) could be performed to evaluate for occult fractures if patient management will be impacted.
Scaphoid fracture – Always remember to request a specific scaphoid view with plain radiographs. Additional imaging with CT for boney detail, osseous alignment, and evaluation of healing progression are sometimes required. NM bone scintigraphy or MRI are both options for the assessment of occult fractures in the appropriate clinical setting. NM has the highest sensitivity for detecting occult fractures, but less specificity, leading to overtreatment more often than when CT and MRI are used. MRI has the added benefit of evaluation of surrounding soft tissues and lack of exposure to ionizing radiation.
Arthritis – Plain films can identify arthritis and degenerative changes and even differentiate inflammatory arthropathy such as rheumatoid from osteoarthritis. Serial radiographs help follow the progression of the disease. Again, CT or MRI can further characterize the processes as needed. Advanced imaging is appropriate in the assessment of early inflammatory arthropathy or osteoarthritis in young patients who may benefit from cartilage replacement procedures. CT or MRI is rarely indicated in advanced osteoarthritis.
Scapholunate dissociation – This condition is initially identifiable with plain films and further characterized by MRI.
Carpal dislocations – Again, plain films are used to identify the particular pathology, and CT or MRI are used to characterize the extent of ligamentous involvement and surgical planning further.
Distal radioulnar joint dislocation or instability – Initial evaluation with radiographs t assess osseous alignment and coexistent fracture followed by MRI to assess ligamentous involvement.
Osseous and non-osseous carpal coalition – Osseous coalitions are identifiable on plain film. If a non-osseous (fibrous) coalition is suspected, MRI or CT can better identify the presence of such findings while MRI may identify associated soft tissue or bone marrow edema, which would support a clinical diagnosis of the asymptomatic fibrous coalition.
Kienböck disease and avascular necrosis – Serial imaging with plain film can identify and follow the progression. MRI is more sensitive and specific for early detection. NM can exclude but is not specific for the diagnosis even if the scan is positive.
TFCC tear – As usual, a good place to start is with plain film assessment. Radiographs are helpful for the diagnosis of soft tissue mineralization such as HADD or chondrocalcinosis, which can be difficult to appreciate on MRI. Additionally, unsuspected fracture or arthritis may be identified on radiographs and thereby explain ulnar sided pain without the need for advanced imaging. CT arthrogram or MRI with or without arthrogram can identify the presence and type of TFCC tear or identify other potential causes of ulnar sided wrist pain such as tenosynovitis or intersection syndrome.
Carpal tunnel syndrome – There is a dedicated plain radiograph to assess the osseous carpal tunnel, but it is limited in identifying the most pathologic causes of this process. Start with plain films, specifically requesting a carpal tunnel view, then proceed to cross-sectional imaging with CT if osseous pathology is expected or US and MRI for soft tissue evaluation. MRI or US can identify imaging findings to support the diagnosis of carpal tunnel syndrome such as median nerve enlargement as well as identify important anatomic variants essential to safe surgical planning such as a persistent median artery. Advanced imaging may also identify soft tissue causes for carpal tunnels, such as accessory muscles or soft tissue masses like ganglion cysts.
Humpback deformity of the scaphoid – Again, this process will be evident on most plain film imaging studies (lateral view particularly) and further characterized with CT for surgical treatment planning.
Osteomyelitis – Radiographs are relatively insensitive for early osteomyelitis however are complementary to advanced imaging. Radiographs may show periostitis or cortical destruction. Both MRI and NM imaging are more sensitive for the detection of osteomyelitis than radiographs. MRI has the advantage of being able to identify the extent of the process, coexistent septic arthrosis, and soft tissue involvement (cellulitis, fasciitis, or abscess).
Metastasis – Osseous lesions can be identified on radiographs when there is advanced destruction; however, the infiltrative marrow-replacing process can be occult on radiographs. Soft tissue masses can soft times be appreciated on radiographs, especially if there are associated osseous remodeling/changes. CT and MRI have a higher sensitivity for the identification of metastasis and better evaluates the extent of disease.
Bone lesions – Radiographs help determine the presence and type of matrix present in a bone lesion (chondroid versus osteoid). Some bone lesions have a characteristic/pathognomic appearance on radiographs, and further imaging is not indicated, such as non-ossifying fibroma (NOF). As previously described, advanced imaging such as CT and MRI better evaluates the extent of disease (i.e., joint or soft tissue involvement) as well as better characterization of the lesion, thereby narrowing the differential diagnosis and allowing for the determination of indication for tissue sampling. CT and MRI also aides in surgical and biopsy planning.