Lecture 7: The Upper Limb Flashcards by Lauren Babcock

What does stylopod refer to?

Arm (humerus)

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What does zygopodium refer to?

Forearm (radius + ulna)

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What does autopodium refer to?

Wrist + hand

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How does the positioning of the upper limb in pronograde posture allow for quadrupedal walking?

Its retroflex positioning leaves the upper limb elbow joint always slightly flexed

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Describe the typical quadrupedal mammal shoulder arrangement, such as is seen in the baboon

Shoulder is placed on the side of the rib cage with the scapula balanced on top of the humerus

The rib cage is narrow side-to-side and deep front to back

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Describe the chimp shoulder in terms of chest shape, scapula placement, clavicle characteristics, and humerus placement

Chest is wide front to back
Scapula is placed on the back
Clavicles are long and angled
Humerus on the side of the rib cage

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Describe the Homo erectus shoulder in terms of chest shape, scapula placement, clavicle characteristics, and humerus placement

Chest is wide front to back
Scapula is placed on the SIDE
Clavicles are long and HORIZONTAL
Humerus is pulled forward, limiting backwards rotation of the arm

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Describe the Homo sapien shoulder in terms of chest shape, scapula placement, clavicle characteristics, and humerus placement

Chest is wide front to back
Scapula is placed on the BACK
Clavicles are SHORT and horizontal
Humerus is placed on the side of rib cage so we can pull our arms back to throw/run

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True or false: the humerus is not considered part of the pectoral girdle

True

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Upward and downward rotation of the scapula changes the orientation of what cavity?

Glenoid

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The position of the pectoral (shoulder) girdle on the thorax is more ________ in quadrupeds, with a clavicle that accommodates a more ____________ positioned shoulder.

The position of the pectoral (shoulder) girdle on the thorax is more __________ in climbers, suspensory, and orthograde/bipedal forms, with curved, thicker clavicle that accommodates a more _________ oriented shoulder with a more cranially oriented glenoid.

Lateral; vertically

Posterior; laterally

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In terms of scapular shape, the glenoid of apes and humans is _________ to accommodate more shoulder mobility.

In quadrupedal monkeys, the glenoid is _________ is shape.

In both cases, the shape of the humeral head mirrors the glenoid (it is more ___________ in apes and humans and more _____ in monkeys).

Rounder

Pririform

Globular; ovoid

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In terms of the shape of the scapula, quadrupeds have a ________ scapula cranially-caudally but ___________ from the vertebral border to axillary border to facilitate movement during quadrupedal locomotion.

Climbers and suspensions forms have ________ scapulae with a more ________ oriented glenoid to allow greater mobility and rotational movement.

Shorter; broader

Long; cranially

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In particular, lengthening of the infraspinous portion of the scapula does what?

Provides greater attachment for muscles that superiorly rotate the glenoid, raising the arm over the head

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What scapular muscle keeps the scapula against the rib cage and also superiorly rotates the glenoid?

Serratus anterior

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What aspect of humerus bone structure offsets the humeral head from the distal articular surface and to what degree does this occur in humans?

Humeral torsion - the shaft of the humerus is twisted

The highest degree of humeral torsion is seen in humans

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The progressive increase in humeral torsion is associated with what locomotion behavior in apes?

Climbing and suspension

It is also thought to be an adaptation for weight-bearing in knuckle walking apes and possible tool use in early hominins

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The idea that humeral torsion in humans is related to tool use corresponds to the _________ oriented shoulder and ___________ oriented elbow; both essential for mobility and manipulation of the upper limb. Humeral torsion is present ________ in ontogeny and affects placement of the ___________ _________ on the humerus, which accommodates the tendon of the ___________ _________.

Laterally
Anteriorly
Early
Bicipital groove
Biceps brachii

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The human upper limb is adapted for use in a lowered position and is less powerful in a raised position. Humans are not powerful climbers and do not naturally suspend.

We have relatively _______supraspinous fossa and _______ infraspinous fossa with ________ rotator cuff muscles.

Upward rotation of the scapula is more like that of quadrupeds. We have lateral facing shoulder joints (instead of cranial) and the _______ end of the clavicle lacks the cranial twist seen in apes.

Small; large; small

Lateral

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The shoulder adaptations from apes to humans may lead to what syndrome associated with repetitive overhead motion?

Shoulder impingement syndrome

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What aspect of the elbow joint limits the degree of extension? - is this a quadrupedal or climbing/suspension trait?

Size of the olecranon (longer = less extension) which is a quadrupedal trait

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How might stronger flexion at the elbow be accommodated anatomically in climbers?

Stronger flexion is accommodated by a higher coronoid process (attachment point for the brachialis - main elbow flexor)

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In terms of comparing the elbow joints of humans and apes, they are overall similar due to similar distal humerus. Differences reflect weight bearing and strength/lever advantages of _________ musculature. Apes have deeper _________ _______ for hyperextension during weight bearing knuckle walking. Apes lateral ___________ ___________ is strongly developed to help stabilize the elbow joint during hyperextension when knuckle walking

Brachial
Olecranon fossa
Trochlear ridge

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The human hand and wrist:

of carpal bones =

of metacarpals =

of phalanges =

Carpals = 8
Metacarpals = 5

Phalanges = 14 (5 digits, each has 3 segments except thumb which has 2)

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Compare the general primitive carpus with modern human carpus

Reduced wrist bones due to fusion

In terms of flexion and extension at the wrist joints: 40% of flexion occurs at the ______________ joint while 60% occurs at the ____________ joint. 33% of extension occurs at the __________ joint while 67% occurs a the _____________ joint.

Radiocarpal; midcarpal Midcarpal; radiocarpal

Radial and ulnar deviation (to achieve abduction and addiction) mostly occurs at which joint?

Midcarpal

The "power grip" consists of strong flexion of what joints and muscle?

MP and IP joints | Flexor digitorum profundus

Compared to apes, we have much more dexterity to our thumbs due to increased musculature and nerve innervation. The bulge of intrinsic thumb muscles that allows for this dexterity is called the __________ __________

Thenar eminence

African ape knuckle-walking features include: Limited degree of wrist _____________ Limited metacarpophalangeal joint ___ and ____ dorsiflexion Deeply __________ distal radial surface Dorsal __________ of metacarpal heads Relatively _________ proximal phalangeal segments

``` Dorsiflexion (extension) II and V Concave Expansion Short ```

Orangutans do not knuckle-walk due to _______ and _________ digits; what is their alternative to knuckle-walking?

Long; curved Orangutans fist-walk

Orangutans have the following adaptations to climbing: _________ and _________ phalangeal segments Metacarpals ____ and ____ show a greater degree of curvature __________ bony cortex of all metacarpals __________ length of the 4th digit relative to other digits

Long; curved II and V Thicker Increased

What anterior pectoral girdle muscle is an upward rotator of the scapula?

Serratus anterior

What anterior pectoral girdle muscle is a downward rotator of the scapula?

Pectoralis minor

What anterior pectoral girdle muscles act as depressors of the clavicle?

Subclavius | Pectoralis minor

What muscles of the anterior pectoral girdle act to protract the scapula?

Serratus anterior | Pectoralis minor

What anterior pectoral girdles muscles act as flexors of the humerus?

Deltoid | Pectoralis major

What anterior pectoral girdle muscle acts as abductor of the humerus?

Deltoid

What anterior pectoral girdle muscle acts to adduct the humerus?

Pectoralis major

What anterior pectoral girdle muscle functions in medial rotation of the shoulder girdle?

Subscapularis

What posterior pectoral girdle muscle(s) act as upward rotators of the scapula?

Trapezius

What posterior pectoral girdle muscle(s) act as downward rotators of the scapula?

Levator scapulae Rhomboids (both) Latissimus dorsi

What posterior pectoral girdle muscle(s) act to retract the scapula?

Rhomboids (both) | Trapezius

What posterior pectoral girdle muscle(s) act to elevate the scapula?

Levator scapulae

What posterior pectoral girdle muscle(s) act as extensors of the humerus?

Deltoid Pectoralis major Latissimus dorsi

What posterior pectoral girdle muscle(s) act as abductors of the humerus?

Deltoid | Supraspinatus

What posterior pectoral girdle muscle(s) act as adductors of the humerus?

Latissimus dorsi | Teres major

What posterior pectoral girdle muscle(s) act as external rotators?

Infraspinatus | Teres minor

What posterior pectoral girdle muscle(s) act as inward rotators?

Latissimus dorsi | Teres major

What are the four rotator cuff muscles and what is their primary function?

Supraspinatus Infraspinatus Teres minor Subscapularis Act to stabilize the shoulder

What two additional muscles make up the pectoral girdle in apes? What are their functions?

Atlantoclavicularis - elevates clavicle | Pectoralis abdominus - flexor of humerus

Pan and gorilla have an occipital protuberance attachment for what muscle?

Rhomboid (remember this is only one muscle in the great apes)

What muscles make up the anterior (flexor) compartment of the arm

Biceps brachii (long and short heads) Brachialis Coracobrachialis

What muscles make up the posterior (extensor) compartment of the arm?

``` Triceps brachii (long, lateral, medial heads) Anconeus ```

What is the primary function of the muscles in the anterior forearm?

Flex the wrist, hand and fingers

What four muscles make up the superficial layer of muscles of the anterior forearm?

Pronator teres Palmaris longus Flexor carpi radialis Flexor carpi ulnaris

What two muscles make up the intermediate layer of the anterior forearm?

Flexor digitorum superficialis (radial head + humeral-ulnar head)

What 3 muscles make up the deep layer of the anterior forearm?

Flexor digitorum profundus Flexor pollicis longus Pronator quadratus

In terms of thumb dexterity, only humans have a separate ________ _________ ___________. This allows for strong independent movement of the thumb

Flexor pollicis longus

What 3 muscles make up the radialis group of the superficial layer of the posterior forearm?

Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis

What is the only forearm muscle that moves the elbow?

Brachioradialis

What is the primary function of the muscles of the posterior forearm?

Extend the wrist, hand, and fingers

What 3 muscles make up the superficial layer of the posterior forearm?

Extensor carpi ulnaris Extensor digitorum Extensor digiti minimi

What 5 muscles make up the deep layer of the posterior forearm?

``` Supinator Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indices ```

What is characteristics of the anatomical position - pronation or supination?

Supination

What are the 2 muscles of the upper limb responsible for pronation? The 2 muscles for supination?

Pronation = pronator teres, pronator quadratus Supination = biceps brachii, supinator

The lumbricles are muscles between the metacarpal bones that attach to the tendons of what other muscle?

Flexor digitorum profundus

What is the function of the lumbricles?

Independent flexion of the MP joints while IP joints are extended

What muscles of the inner hand adduct the fingers?

Palmar interosseous muscles Think PAD - palmar=adduct

What muscles of the inner hand abduct the fingers?

Dorsal interosseous muscles Think DAB - dorsal=abduct

What are the 3 hypothenar muscles?

Muscles associated with the pinky Opponens digiti minimi Flexor digiti minimi brevis Abductor digiti minimi

What are the 5 thenar muscles?

Muscles associated with the thumb Adductor pollicis (transverse + oblique head) Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis

In comparing the hand musculature in humans and apes: The long hand musculature (tendons from forearm) are more developed and stronger in _______ The short hand musculature (intrinsic hand muscles) are much more developed in _______

Apes | Humans

What nerves provide innervation to the upper limb and shoulder?

Brachial plexus

What spinal nerve roots make up the brachial plexus in humans?

C5-8 and T1

What spinal nerve roots make up the brachial plexus in Papio (baboon)?

C5-T1 (same as human) - just differences in which nerve roots certain named nerves arise from

What spinal nerve roots make up the brachial plexus in Pan (chimp)?

C4-C8

The general pattern of blood supply to the upper limb: The posterior shoulder is supplied by branches of the _________ and _________ arteries. The pectoral region is supplied by branches of the ________ artery.

Subclavian; axillary Axillary

What muscle acts as a landmark to divide the axillary artery into 3 main portions?

Pectoralis minor

The general pattern of blood supply to the upper limb: The arm is supplied by the _________ artery and its branches The forearm is supplied by the _________ and _______ arteries The hand is supplied by the ______ and ________ arteries

Brachial Radial; ulnar Radial; ulnar

In terms of superficial veins of the upper limb, humans have a distinct _______ vein, whereas baboons, gorillas, and chimps do not. Also the ______ vein is more extensive in humans than in other apes

Basilic | Cephalic

The 1934 Miller article uncles observations upon the arrangement of the axillary artery and brachial plexus. In summary the ______ tends to accommodate the ______ most of the time.

Artery; brachial plexus